GB2586159A

GB2586159A - Apparatus and methods for compressing stacks of articles

Info

Publication number: GB2586159A
Application number: GB1911369.5A
Authority: GB
Inventors: Payne Philip; Brown Richard; Darnell Antony; Morgan Gavin; Barrow David
Original assignee: Kimberly Clark Worldwide Inc; Kimberly Clark Corp
Current assignee: Kimberly Clark Worldwide Inc; Kimberly Clark Corp
Priority date: 2019-08-08
Filing date: 2019-08-08
Publication date: 2021-02-10
Anticipated expiration: 2039-08-08
Also published as: GB201911369D0; GB2586159B

Abstract

A method of compressing stacks 900 of articles using an automated machine 700 comprising opposed endless coextending conveyor belts with diverging outfeed ends by passing a stack of articles between the belts. Ideally the angle of divergence is 5°-15°. One belt may be adjustable to vary the angle. The belts may converge at the infeed upstream region and be adjustable between 5° and 20° there. Between the infeed and outfeed regions the belts can be parallel or gently converge. The spacing between the belts can vary between 5mm and 50mm. The belts can be driven around pulleys. Three sequential opposed pairs of pulleys can impose a compressive force in the intermediate region. The end pulleys in the sequence can have a larger diameter than intermediate pulleys and the belt can wrap around them by an angle of less than 60°. The infeed and outfeed sections can also have multiple sequential pulley pairs. The angles and gap sizes between the belts can be independently variable. One belt can extend generally horizontally and the other can be above it only being horizontal in the intermediate section. The infeed and outfeed regions can each be longer than the intermediate compression region.

Description

APPARATUS AND METHODS FOR COMPRESSING STACKS OF ARTICLES

FIELD

The present invention relates to apparatus and methods for compressing a stack of articles. The invention is particularly, although not exclusively, directed to apparatus and methods for compressing a stack of articles prior to packaging of the stack of articles, and, more specifically, to compressing a stack of unpackaged articles prior to packaging of the stack of articles. The invention is applicable to compressing stacks of articles of various types. For example, the invention may be applied to compressing a stack of absorbent articles. In some exemplary embodiments, the invention is applied to compressing a stack of tissue paper products e.g. folded tissue paper products prior to packaging of the tissue paper products, such as in an outer carton.

BACKGROUND

It is often desirable to compress a stack of articles before the stack is packaged.

For example, reducing the overall height of the stack through such compression may reduce the dimensions of the packaging required.

Various techniques for individually compressing packaged articles are known. For example, EP 0733551A1 discloses a method in which products to be compressed are located, already individually packaged in a partially sealed container of airtight material, on an initial segment of a first endless conveyor belt. The article in its container is compressed using an articulated portion of a second endless conveyor belt superimposed on the initial segment, and which is actuated between a raised inclined position for receiving individual products, between the initial segment and the portion, and a lowered position, in which the presser element compresses the product to a desired thickness, and guides the product as it advances toward mutually superimposed parallel sections of the first and second conveyors. The container is hermetically sealed downstream of the superimposed sections of the conveyor.

Compressing a stack of articles, in particular prior to packaging of the stack, i.e. a "naked" stack of articles, presents additional challenges in terms of maintaining stack stability. One such example of an unpackaged stack of unpackaged articles is a stack of tissue paper products. It is desirable to be able to compress a stack of tissue paper products before inserting the stack of tissue paper products into an outer carton. Currently it is necessary to manually compress such stacks prior to packaging.

EP 2680732A2 discloses a carton for dispensing a compressed stack of tissues. The stack of tissues is subjected to a compressive force by a continuous rotating belt. However, this document does not address the problems of maintaining stack stability and avoiding damage to tissues in the stack which may occur, particularly in the context of compressing an unpackaged stack of articles.

The present invention is directed to methods and apparatus which enable stacks of articles to be compressed in an automated manner, prior to packaging of the stacks.

SUMMARY

In accordance with a first aspect of the invention there is provided an apparatus for compressing stacks of articles, wherein the apparatus defines an infeed region, a compression region and an outfeed region, and is arranged to convey stacks of articles along a path in a machine direction in use sequentially through the infeed region, compression region and outfeed region; wherein the apparatus comprises a first endless conveyor belt on one side of the path along which stacks of articles move in a machine direction in use through the infeed region, compression region and outfeed region, and a second endless conveyor belt on an opposite side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region, wherein the first and second endless conveyor belts travel along respective first and second endless conveyor belt paths in the form of continuous loops, and wherein the infeed region, compression region and outfeed region are each defined between respective opposed portions of the paths of the first and second endless conveyor belts on either side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region; wherein the respective opposed portions of the paths of the first and second endless conveyor belts defining the outfeed region diverge from one another along the machine direction.

Thus, in accordance with the invention, an apparatus for compressing stacks of articles is provided which includes an infeed region, a compression region and an outfeed region, and is adapted to convey stacks of articles through these regions in tum. The direction of travel of stacks of articles from the infeed region through the compression region and to the outfeed region defines a machine direction of the apparatus.

The infeed, compression and outfeed regions are each defined between respective opposed portions of the paths travelled by first and second endless conveyor belts, which first and second endless conveyor belts are located on opposite sides of a path along which stacks of articles move through the apparatus in the machine direction. The opposed portions of the paths of the first and second endless conveyor belts are portions in which the first and second endless conveyor belts face one another.

The first and second endless conveyor belts are on opposite sides of the path along which stacks of articles move in the machine direction through the apparatus in use. The path of the stacks of articles extends between the first and second endless conveyor belts.

The path of the stacks of articles herein refers to the general direction of travel of the stacks of articles through the apparatus. It will be appreciated that, in embodiments, the stacks of articles are supported on one of the first and second endless conveyor belts e.g. the second endless conveyor belt as they travel along the path through the infeed, compression and outfeed regions. The first and second endless conveyor belts are arranged so as to be on opposed sides of the stacks of articles as the stacks of articles travel along the path of the stacks through the infeed, compression and outfeed regions. Thus the apparatus may be said to comprise a first endless conveyor belt arranged to be on one side of stacks of articles as they travel along their path through the infeed region, compression region and outfeed region in use, and a second endless conveyor belt arranged to be on an opposite side of stacks of articles as they travel along their path through the infeed region, compression region and outfeed region in use.

The first and second endless conveyor belts are each endless conveyor belts. An endless conveyor belt as used herein refers to a conveyor belt which travels along a path in the form of a continuous loop. Thus, the first and second endless conveyor belt paths are each in the form of a continuous loop. For brevity, the first and second endless conveyor belts may be referred to as the first and second conveyor belts herein, and any further endless conveyor belt may be referred to simply as a "conveyor belt".

The first and second endless conveyor belts each travel around a respective (set of a) plurality of pulleys when traversing their respective path. Any reference to a pulley around which the first or second conveyor belt travels herein, refers to a pulley from a plurality of pulleys around which the respective conveyor belt travels as it traverses its respective path. These pulleys may form part of a respective conveyor belt assembly as described later. Unless stated otherwise, any pulley may be a drive pulley or a driven (or guide) pulley, and various configurations of drive and driven (or guide) pulleys are possible.

The apparatus is configured to compress stacks of articles automatically as they pass along a path through the apparatus in the machine direction in use. The apparatus is configured to automatically compress stacks of articles continually supplied to the infeed region as the stacks of articles pass through the apparatus in the machine direction. Each stack of articles is compressed between the first and second endless conveyor belts as the stack passes through the apparatus in the machine direction in use.

The opposed portions of the paths of the first and second endless conveyor belts providing the outfeed region diverge from one another along the machine direction i.e. in the direction away from the compression region. In this way a tapered outfeed is provided. It has been found that by providing a diverging belt outfeed region, the stability of stacks emerging from the compression region may be improved. Such an outfeed region may provide a more gradual transition from the compression region, with stacks being guided between the diverging belts as they emerge from the compression region. The use of a tapered outfeed may provide a gradual release of the compression force, and guidance of the stack and its articles as the compression force is released. As they travel through the outfeed region, stacks of articles may recover slightly in height following compression in the compression region, enabling them to remain in contact with both belts over at least an upstream portion of the outfeed region. It has been found that the likelihood of articles in stacks being damaged and of the stack being distorted may be reduced in comparison to an arrangement in which no such tapered outfeed is provided, with compression instead being ended abruptly e.g. where an upper endless conveyor belt simply turned around a pulley at the end of a compression region to commence its return path. As discussed in more detail below, the presence of an outfeed region of the configuration of the present invention may reduce the risk of articles in the stack becoming misaligned, and hence of the stack deviating from a desired stack alignment e.g. from a square or rectangular shape when viewed from the side in the machine direction. Such deviation from desired alignment may be referred to herein as "rhombusing".

The opposed portions of the paths of the first and second endless conveyor belts diverge from one another along substantially an entire length of the outfeed region. Thus, the outfeed region may be defined as a region in which opposed portions of the first and second endless conveyor belts diverge from one another. The first and second endless conveyor belts are inclined relative to one another in the outfeed region. Thus, the conveyor belts gradually diverge from one another in this region. In embodiments the compression region transitions smoothly into the outfeed region, e.g. as the first endless conveyor belt passes around a pulley to change a direction of the path thereof.

The opposed portions of the paths of the first and second endless conveyor belts defining the outfeed region may diverge from one another along the machine direction so as to define an outfeed angle corresponding to an angle of divergence of the paths of the first and second endless conveyor belts in the outfeed region. The outfeed angle may be any suitable angle greater than zero, such as at least about 5 degrees, or at least about 8 degrees. The outfeed angle may be less than 45 degrees, such as less than about 25 degrees, or less than about 20 degrees. In some embodiments the outfeed angle is in the range of from about 5 degrees to about 45 degrees, or from about 5 degrees to about 15 degrees. Such ranges have been found to be particularly effective for use in compressing stacks of tissue paper products. It will be appreciated that the most appropriate value for the outfeed angle will depend upon various parameters, such as the compression gap size, type of articles, and the intended compressed dimensions of the stacks of articles etc. Preferably the angle of divergence of the first and second endless conveyor belts (the outfeed angle) is constant along a length of the outfeed region in the machine direction e.g. over substantially the entire length thereof. The opposed portions of the paths of the first and second endless conveyor belts in the outfeed region may define respective planes, the planes diverging from one another along the machine direction. The outfeed angle may be defined by the angle subtended by the planes at a notional point of intersection of the planes. It will be appreciated that the paths of the first and second endless conveyor belts do not actually intersect at the upstream end of the outfeed region, as the belts are separated at that point by an applicable compression gap.

A plane defined by either one of the first and second endless conveyor belts, or indeed any other endless conveyor belt mentioned herein, may be taken to be the plane defined by a stack facing (or outer) surface of the belt, unless the context demands otherwise. The path of a portion of the first or second endless conveyor belt in the infeed, compression or outfeed region, or indeed of any other portion of the path of the first or second endless conveyor belt, or of any other endless conveyor belt which contacts stacks of articles referred to herein, may be defined by reference to the path of the stack facing, outer surface of the belt, unless the context demands otherwise.

The path of at least one of the first and second endless conveyor belts may be curved over a short distance as the compression region smoothly transitions into the outfeed region e.g. as it passes around a pulley providing a transition between the compression and outfeed regions. In embodiments the path of the first endless conveyor belt is curved in this way. Such a transition, which is of negligible length in comparison to the length of the outfeed region, should be disregarded when determining a general path of the applicable conveyor belt or belts through the outfeed region e.g. when determining a plane defined by the path of a belt, or an angle of divergence between paths of the belts in the outfeed region.

The apparatus is preferably configured such that the outfeed angle is adjustable. In embodiments the relative position of the opposed portions of the paths of the first and second endless conveyor belts defining the outfeed region is adjustable in order to vary the outfeed angle. In embodiments the outfeed angle may be variable in order to provide an outfeed angle anywhere within the above exemplary ranges of outfeed angle. The outfeed angle is preferably adjustable only when the first and second endless conveyor belts are not running Thus the outfeed angle may be adjustable only between runs of the apparatus, and not during a given run thereof. Preferably the path of the second endless conveyor belt is fixed in the outfeed region, and the path of the first endless conveyor belt is adjustable relative thereto (in the outfeed region) in order to vary the outfeed angle. This may be achieved in any suitable manner. An adjustable outfeed angle enables the outfeed angle to be tailored as appropriate to a particular context e.g. based on the type of articles in the stack, pre-compression stack height and post-compression stack height, and enables adjustment of the angle based on feedback of compressed stack properties. For example, where the compressed stacks of articles do not exhibit desired levels of stability e.g. are rhombussed to an extent, and/or wherein articles in the stacks exhibit signs of damage, such as tearing, the outfeed angle may be adjusted to try to address such problem(s).

The outfeed angle may be adjusted to adjust a rate at which pressure is released on the stacks as they are conveyed through the outfeed region i.e. the steepness of the divergence of the belts in the region and/or a point at which a compressed stack of articles is expected to no longer contact the e.g. upper one of the belts.

Stacks of articles will contact the opposed surfaces of the first and second endless conveyor belts through the compression region, and through at least an upstream portion of the outfeed region. The stacks of articles are sandwiched between the opposed surfaces of the belts. The opposed surfaces are the outer, stack facing surfaces of the belts. As stacks of articles leave the compression region, they will tend to recover in height to some degree, such that they will continue to contact the opposed surfaces of the first and second endless conveyor belts even as the belts diverge through at least an upstream portion of the outfeed region.

It has been found that, in a similar way to that in which an outside runner must run faster than an inside runner to maintain a position on the track as they run the curved portion of an athletics track, as a belt is of non-negligible thickness, an outer surface of the belt will travel faster when travelling around a pulley circumference than the inner surface of the belt. Taking, as an example, the case in which stacks of articles are located between, and contact, upper and lower endless conveyor belts as they travel through a compression region, if the lower conveyor belt followed a level path through the compression region and downstream thereof, and the upper conveyor belt wrapped around a pulley at the downstream end of the compression region to commence a return path, the outer, stack facing surface of the upper conveyor belt would start to accelerate as it wrapped around the pulley at the end of the compression region. However, the outer, stack facing surface of the lower conveyor belt, which has a straight path through this region, would continue at the same speed that it travelled in the compression region. Thus, a speed differential between the outer, stack facing surfaces of the belts would arise, causing the uppermost surface of the uppermost article in each stack to accelerate just at the point where the stack of articles stopped contacting the outer surface of the upper conveyor belt. This may result in top surface e.g. layer of an uppermost article in the stack travelling at a greater speed than a bottom surface e.g. layer thereof, subjecting the article to a shearing force. The article may then exhibit a tendency to tear. The acceleration of the outer surface of the upper conveyor belt might also tend to introduce a speed differential between the upper and lower ends of the stack, increasing the likelihood of stack misalignment e.g. rhombussing. Such problems would be associated with using an arrangement of the type disclosed in EP 2680732 to compress a stack of unpackaged articles. These problems may be addressed in accordance with embodiments of the invention, by providing a diverging outfeed region at the end of the compression region. In this way, a wrap angle defined between one of the first and second endless conveyor belts e.g. the first endless conveyor belt with a pulley at a downstream end of the compression region may be reduced, enabling any significant acceleration of the stack facing outer surface of the belt due to travel around the circumference of the pulley to be avoided.

In preferred embodiments, the opposed portions of the paths of the first and second endless conveyor belts defining the infeed region converge with one another along the machine direction. Thus, a converging belt infeed is provided. In this way, a tapered infeed region is provided. This may further help to support stacks as they enter the compression region, and maintain stack stability. The opposed portions of the paths of the first and second endless conveyor belts may converge with one another along the machine direction along substantially an entire length of the infeed region. The infeed region may be defined as a region in which opposed portions of the paths of the first and second endless conveyor belts converge with one another. The first and second endless conveyor belts are inclined relative to one another in the infeed region. Thus, the conveyor belts gradually converge with one another in this region. It will be appreciated that there may be a smooth transition between the infeed region and compression region, such that the path of at least one of the first and second endless conveyor belts is curved over a short transition region e.g. as it passes around a pulley providing a transition between the infeed and compression regions.

The opposed portions of the paths of the first and second endless conveyor belts defining the infeed region may converge with one another along the machine direction so as to define an infeed angle corresponding to an angle of convergence of the paths of the first and second endless conveyor belts in the infeed region. The infeed angle may be in the range of up to about 45 degrees, such as up to about 20 degrees or up to about 15 degrees. The infeed angle may be any suitable angle greater than zero. The infeed angle may be at least 5 degrees. Such values of the infeed angle have been found to be particularly useful in the context of compressing stacks of tissue paper products, although the most appropriate angle will depend upon various factors such as the pre-compressed stack height, compression gap size, nature of the articles etc. Preferably the angle of convergence of the first and second endless conveyor belts (the infeed angle) is constant along a length of the outfeed region in the machine direction e.g. over substantially an entire length thereof. The opposed portions of the paths of the first and second endless conveyor belts may define respective planes in the infeed region, the planes converging with one another along the machine direction. The infeed angle may be defined by the angle subtended by the planes at a notional point of intersection of the planes. It will be appreciated that the paths of the first and second endless conveyor belts do not actually intersect at the downstream end of the infeed region, as the belts are separated at that point by an applicable compression gap. In embodiments the infeed region smoothly transitions into the compression region e.g. as the first endless conveyor belt passes around a pulley to change a direction of the path thereof.

It will be appreciated that the path of at least one of the first and second endless conveyor belts may be curved over a short distance as the infeed region smoothly transitions into the compression region e.g. as it passes around a pulley providing a transition between the infeed and compression regions. In embodiments the path of the first endless conveyor belt is curved in this way. Such a transition, which is of negligible length in comparison to the length of the infeed region should be disregarded when determining a general path of the applicable conveyor belt through the infeed region e.g. when determining a plane defined by the path of a belt, or an angle of divergence between paths of the belts in the infeed region.

The apparatus is preferably configured such that the infeed angle is adjustable. In embodiments the apparatus may be configurable to permit variation of the infeed angle to any value within the above described ranges. In embodiments the relative position of the opposed portions of the paths of the first and second endless conveyor belts defining the infeed region is adjustable in order to vary the infeed angle. The infeed angle is preferably adjustable only when the first and second endless conveyor belts are not running. Thus the infeed angle may be adjustable only between runs of the apparatus, and not during a given run thereof. Preferably the path of the second endless conveyor belt is fixed in the infeed region, and the path of the first endless conveyor belt is adjustable relative thereto (in the infeed region) to vary the infeed angle. This may be achieved in any suitable manner, as discussed below. An adjustable infeed angle enables the infeed angle to be tailored as appropriate to a particular context e.g. based on the type of articles in the stack, pre-compression stack height and compression gap, and enables adjustment of the angle based on feedback of compressed stack properties. For example, where the compressed stacks of articles do not exhibit desired levels of stability e.g. are rhombussed to an extent, the infeed angle may be adjusted to try to address this problem. The adjustable infeed angle also enables different stack sizes to be accepted for compression. In embodiments the infeed angle may be adjusted to control a point at which the uppermost article in a stack will contact the first endless conveyor belt, and thus the length over which gradual compression of the stack will occur, and/or to adjust the rate at which compression of the stacks occurs i.e. the steepness of the convergence of the belts.

The divergence of the paths of the first and second endless conveyor belts in the outfeed region and/or the convergence thereof in the infeed region described herein may be a linear convergence or divergence as appropriate.

It will be appreciated that some compression of a stack of articles may occur before the articles reach the compression region i.e. in the infeed region. However, the compression region at least maintains the articles in a compressed state. The compression force acting on a stack of articles is gradually released as the stack moves through the diverging outfeed region. The compression region is an extended region in the machine direction, rather than merely a nip point. The portion of the path of the first endless conveyor belt of the opposed portions of the paths of the first and second endless conveyor belts defining the compression region may be a portion of the path of the first endless conveyor extending between pulleys around which the first endless conveyor belt travels as part of the first endless conveyor path, the pulleys being spaced from one another along the machine direction. The first endless conveyor travels around each pulley so as to wrap around a portion of the circumference of the pulley. In these embodiments, the pulleys are pulleys which provide a transition between the infeed region and compression region, and the compression region and outfeed region. It will be appreciated that other pulleys may be located between these pulleys which define the start and end of the compression region.

In some embodiments the opposed portions of the paths of the first and second conveyor belts defining the compression region do not converge or diverge along the machine direction. The opposed portions of the paths of the first and second endless conveyor belts defining the compression region preferably extend substantially parallel with one another along the machine direction. Thus, a parallel belt compression region is preferably provided. The opposed portions of the paths of the first and second endless conveyor belts may be substantially parallel with one another along the machine direction along substantially an entire length of the compression region. The compression region may then be defined as a region in which opposed portions of the paths of the first and second endless conveyor belts are substantially parallel with one another. In embodiments the opposed portions of the paths of the first and second endless conveyors may thus extend substantially parallel with one another throughout substantially the entire compression region e.g. substantially the entire length and width thereof As mentioned above, the infeed region may smoothly transition into the compression region, and the compression region may smoothly transition into the outfeed region. Any slight deviation in the path of the belts at the ends of the compression region by virtue of such transitions, which are short in comparison to the length of the compression region, should be disregarded when considering the general path of the belts in the compression region or the size of the compression gap.

In other embodiments the opposed portions of the paths of the first and second endless conveyor belts defining the compression region may converge with one another along the machine direction. The opposed portions of the paths of the first and second endless conveyor belts defining the compression region may converge with one another at a given angle of convergence. The angle of convergence may be less than 20 degrees, or less than 15 degrees, or less than 10 degrees, or less than 5 degrees.

The opposed portions of the paths of the first and second endless conveyor belts may define respective planes in the compression region, the planes converging with one another along the machine direction. An angle of convergence of the paths of the first and second endless conveyor belts in the compression region may be defined by the angle subtended by the planes at a notional point of intersection of the planes. It will be appreciated that the paths of the first and second endless conveyor belts do not actually intersect in the compression region, as the belts are separated by an applicable compression gap. In embodiments the infeed region smoothly transitions into the compression region and the compression region smoothly transitions in the outfeed region e.g. as the first endless conveyor belt passes around respective pulleys at each end of the compression region to change a direction of the path thereof.

Where the opposed portions of the paths of the first and second endless conveyor belts defining the infeed region converge with one another, the opposed portions of the paths of the first and second endless conveyor belts defining the compression region converge with one another less steeply than the opposed portions of the paths of the first and second endless conveyor belts defining the infeed region. Thus, distinct and identifiable infeed and compression regions are provided. A discontinuity in the angle of convergence occurs at the transition between the infeed and compression regions. In embodiments in which the portions of the paths of the first and second endless conveyor belts defining the infeed region converge with one another along the machine direction, the paths of the first and second endless conveyor belts converge with one another along the machine direction with a first angle of convergence in the infeed region, and wherein the paths of the first and second endless conveyor belts converge with one another with a second angle of convergence in the compression region, wherein the first angle of convergence is greater than the second angle of convergence. The ratio of the first angle of convergence to the second angle of convergence may be at least 2:1 or at least 3:1.

The first and second endless conveyor belts are spaced from one another in the compression region to provide a compression gap. A compression gap size of the compression gap may be defined. The compression gap size is the closest spacing between the first and second endless conveyor belts in the compression region. The compression gap size may thus be defined as the closest spacing between the stack facing surfaces (outer surfaces) of the first and second endless conveyor belts in the compression region. The compression gap size is measured while the belts are not running. Thus, the compression gap may measure a vertical closest spacing between the belts in the compression region.

In embodiments the spacing between the first and second endless conveyor belts is constant along substantially an entire length of the compression region. The spacing between the first and second endless conveyor belts may be constant throughout the entire compression region i.e. throughout the entire length and width thereof. The width of the compression region is defined in the cross direction. This may be achieved using an arrangement in which the opposed portions of the first and second endless conveyor belts are substantially parallel to one another in the compression region.

The compression gap size may be adjustable to enable the apparatus to be used with different stacks of articles e.g. different types of articles and/or initial stack dimensions. The compression gap size may be adjustable only when the first and second endless conveyor belts are not running. Thus the compression gap size may be adjustable only between runs rather than during running of the apparatus to compress stacks of articles.

The infeed region may transition directly into the compression region, and the compression region may transition directly into the outfeed region. The transition between the infeed region and the compression region, and the transition between the compression region and the outfeed region may be smooth transitions, as previously described. Thus, the paths of one or both of the first and second endless conveyor belts may briefly deviate from the paths followed in the infeed and compression regions, or outfeed and compression regions, at the transitions therebetween, e.g. as one or both belts follow the curvature of a pulley defining a transition between the regions. Such brief deviations are not considered to impact upon the general path or plane of the path defined by a belt in a respective one of the regions as described herein, or the relative paths of the belts.

In embodiments the first endless conveyor belt travels around a pulley to change a direction of the path of the belt at a transition between the compression and outfeed regions. The first endless conveyor belt may define a wrap angle with the pulley of less than 120 degrees. The wrap angle is optionally less than 90 degrees, less than 60 degrees or less than 45 degrees. A wrap angle as referred to herein is the angle subtended between the points on the circumference of the pulley defining the start and the end respectively of a section of the circumference of the pulley along which the belt contacts the pulley surface. The pulley may correspond to the first outfeed region pulley described below.

Alternatively or additionally the first endless conveyor belt may travel around a pulley to change a direction of the path of the belt at a transition between the infeed and compression regions. The first endless conveyor belt may define a wrap angle with the pulley of less than 120 degrees. The wrap angle is optionally less than 90 degrees, less than 60 degrees or less than 45 degrees. The wrap angle refers to the angle subtended between the start and the end of a section of the circumference of the pulley along which the belt contacts the pulley surface.

The length of the compression region and/or the size of the compression gap may be selected as appropriate taking into account the nature of the articles in the stack, the initial dimensions of the stack, the spacing of stacks along the machine direction etc. For example, as described in more detail below, the length of the compression region may advantageously be selected to exceed a length of a stack of articles to be compressed along the machine direction, such that the entirety of a stack may be located within the compression region when the apparatus is run in use.

In some exemplary embodiments the length of the compression region may be in the range of from about 100m to about 300mm, optionally from about 175mm to about 275mm, and optionally from about 200mm to about 250mm. Such dimensions may be particularly useful, for example, in compressing stacks of tissue paper products. The length of the compression region may be defined as discussed below, as the shortest distance between the axes of pulleys defining a transition between the infeed and compression region and compression region and outfeed region respectively. This may correspond to a distance along the machine direction.

In some exemplary embodiments the size of the compression gap is in the range of from about 2mm to about 75 mm or from about 5mm to about 50mm. Such ranges have been found to be particularly appropriate for compressing stacks of tissue paper products.

Where the size of the compression gap is variable it may be variable to provide a value anywhere within such ranges.

Where any one or ones of an infeed angle, outfeed angle and compression gap size of the apparatus are variable, the apparatus is preferably configured such that these parameters are variable independently of one another. Examples of the way in which this may be achieved are discussed below.

In embodiments a length of the outfeed region is greater than a length of the compression region. Alternatively or additionally, a length of the infeed region may be greater than a length of the compression region. The length of the outfeed region may be less than a length of the infeed region. The length of the various regions may be defined as discussed below, as the shortest distance between the axes of pulleys defining the start and end of the regions. Such a distance may be correspond to a distance along the machine direction.

It will be appreciated that the infeed region, compression region and outfeed region are provided between respective (pairs of) opposed portions of the paths of the first and second endless conveyor belts. The infeed, compression and outfeed regions may be provided respectively between such pairs of opposed portions which may be referred to as the first, second and third pair of opposed portions of the paths respectively. The opposed portions of the paths of the first and second endless conveyor belts diverge from one another in the outfeed region along the machine direction. The opposed portions of the paths of the first and second endless conveyor belts preferably converge with one another in the infeed region along the machine direction. The opposed portions of the paths of the first and second endless conveyor belts preferably extend substantially parallel to one another in the compression region. References herein to a portion of a conveyor belt should be understood to refer to a portion which defines a portion of the path along which the belt travels if not explicitly stated, unless the context demands otherwise. When the belt moves in use the actual part of the belt defining the portion of the belt which provides a given portion of the path will, of course, change continually.

The first and second endless conveyor belts (or the paths thereof) are spaced from one another to enable stacks of articles to pass therebetween in the infeed, compression and outfeed regions (i.e. throughout these regions). Thus opposed portions of the paths of the first and second endless conveyor belts providing the infeed, compression and outfeed regions are spaced from one another to enable stacks of articles to pass therebetween in use. The opposed (i.e. facing) surfaces of the first and second endless conveyor belts are not in contact with one another in the infeed, compression and outfeed regions. The spacing of the first and second endless conveyor belts (or the paths thereof) may vary between and, in some cases within, the respective regions as described herein (resulting in varying degrees of compression being exerted on the stack in the different regions). The spacing of the belts (or the paths thereof) may be substantially constant at any point across the cross machine direction at any point along the machine direction in each one of the infeed, compression and outfeed regions. The cross section of the path of each belt taken in the cross machine direction may be substantially planar in (and throughout) any one, and optionally each one of the infeed, compression and outfeed regions.

In embodiments at least the opposed portions of the paths of the first and second endless conveyor belts forming the infeed, compression and outfeed regions of the apparatus are located one above the other, e.g. with those portions of the first endless conveyor belt being above the respective opposed portions of the second endless conveyor belt. The path of the first endless conveyor belt may be located above the path of the second endless conveyor belt at least through the infeed, compression and outfeed regions. The first and second endless conveyor belts may be referred to as upper and lower conveyor belts respectively.

In accordance with the invention in any of its aspects or embodiments, stacks of articles are located between opposed i.e. facing surfaces of the first and second endless conveyor belts when travelling through each of the infeed, compression and outfeed regions. The opposed i.e. facing surfaces of the first and second endless conveyor belts are the outer, stack facing surfaces of the belts in use. The apparatus is configured such that each stack of articles (e.g. upper and lower surfaces thereof) will contact the opposed surfaces of both of the first and second endless conveyor belts when travelling through the compression region, when travelling through at least an upstream portion of the outfeed region, and preferably when travelling through at least a downstream portion of the infeed region. The contact in the different regions will occur at different times as the stack travels through the apparatus from one region to the next. The apparatus is configured such that a stack of articles is also located between the opposed surfaces of the first and second endless conveyor belts, and will contact the opposed surfaces of both the first and second endless conveyor belts, when travelling through a transition between the compression region and the outfeed region, and, where applicable, when travelling through a transition between the infeed region and the compression region. References to a stack of articles contacting surfaces of both conveyor belts when travelling through a given region refers to the stack of articles simultaneously contacting the opposed surfaces of each conveyor belt. The stacks of articles are sandwiched between the opposed surfaces of the belts. Each one of the first and second endless conveyor belts may be considered to have a stack facing surface. At least a portion of this surface will contact one or more stack at any given time. This corresponds to an outer surface of the belt (also referred to the "second" surface of the belt herein).

A point at which a stack of articles will cease to contact the opposed surfaces of both the first and second endless conveyor belts in the outfeed region, and optionally at which the stack will start to contact the opposed surfaces of both of the first and second endless conveyor belts in the infeed region may be set as desired, and is discussed below in more detail in relation to the method aspects of the invention. This may be set by reference to an angle of convergence or divergence of the belts in the relevant region, the stack height dimensions, and, in the case of the outfeed region, the degree to which the compressed stack will start to recover once it leaves the compression region. The stack contacts the opposed surfaces of both of the first and second endless conveyor belts as the stack travels through the entire length of the compression region. Contact between the stacks of articles and both of the facing surfaces of the conveyor belts in at least a downstream portion of the infeed and/or an upstream portion of the outfeed region may help to guide the stacks as they enter or leave the compression region, improving stack stability and reducing the risk of surface damage. In preferred embodiments a stack contacts the opposed surfaces of both of the first and second endless conveyor belts as the stack travels through only a portion of a length of one or both of the infeed and outfeed regions. This may help to avoid contact between the stacks and a region in which one of the endless belts e.g. the first endless conveyor belt wraps around a pulley at the upstream end of the infeed region or the downstream end of the outfeed region. As described above, a belt speed differential which may arise at such a point may undesirably increase the risk of damage to articles in the stack, or stack instability.

In some embodiments the stacks of articles are supported by and contact the second endless conveyor belt throughout their travel through the infeed region, compression region and outfeed region. The second endless conveyor belt may convey the stacks through the regions. A lower surface of each stack of articles may contact the second endless conveyor belt. The stacks of articles (e.g. an upper surface thereof) may contact the first endless conveyor belt throughout the compression region and through at least a portion of the infeed and outfeed regions.

It will be seen that the spacing between the first and second endless conveyor belts varies along the machine direction through the infeed, compression and outfeed regions. Variation in the spacing between the first and second endless conveyor belts in and/or between the infeed, compression and outfeed regions to provide a diverging outfeed, and in embodiments, converging infeed, may be achieved through relative deviation in the paths of the first and second endless conveyor belts in the applicable direction e.g. vertically. This may involve a deviation in the path of either or both of the conveyor belts along the machine direction so as to provide the required relative spacing of the belts in the regions.

In preferred embodiments in which the first endless conveyor belt is located above the second endless conveyor belt in the infeed, compression and outfeed regions, preferably the path of the second endless conveyor belt defines a single plane through each of the infeed, compression and outfeed regions, and preferably extends level e.g. substantially horizontally through the infeed, compression and outfeed regions for supporting stacks of articles as they travel through the infeed, compression and outfeed regions. The level of the path of the second endless conveyor belt then varies (vertically) relative to the level of the path of the second endless conveyor belt between, and as appropriate through, the infeed, compression and outfeed regions to provide the required configuration of the opposed portions of the paths in these regions. Preferably the path of the second endless conveyor belt extends substantially horizontally through the infeed, compression and outfeed regions for supporting stacks of articles as they travel through the infeed, compression and outfeed regions.

The path of the first endless conveyor belt diverges from the path of the second endless conveyor belt in the outfeed region. Preferably the path of the first endless conveyor belt converges with the path of the second endless conveyor belt in the infeed region. In particularly preferred embodiments, the path of the second endless conveyor belt extends level e.g. horizontally through the infeed, compression and outfeed regions for supporting stacks of articles as they travel through the infeed, compression and outfeed regions, and the path of the first endless conveyor converges with the path of the second endless conveyor belt along the machine direction in the infeed region, extends substantially parallel to the path of the second endless conveyor belt in the compression region or converges with the path of the second endless conveyor belt along the machine direction less steeply than in the infeed region, and diverges from the path of the second endless conveyor belt along the machine direction in the outfeed region. In embodiments in which the path of the first endless conveyor belts converges with the path of the second endless conveyor belt along the machine direction in the compression region, the paths of the first and second endless conveyor belts may converge with one another along the machine direction with a first angle of convergence in the infeed region, and the paths of the first and second endless conveyor belts may converge with one another with a second angle of convergence in the compression region, wherein the first angle of convergence is greater than the second angle of convergence. The ratio of the first angle of convergence to the second angle of convergence may be at least 2:1 or at least 3:1.

The path of the first endless conveyor belt (and hence the first endless conveyor belt) may be inclined relative to the path of the second endless conveyor belt (and hence the second endless conveyor belt) so as to approach the path of the second endless conveyor belt in the infeed region. The path of the first endless conveyor belt (and hence the first endless conveyor belt) is inclined relative to the path of the second endless conveyor belt (and hence the second endless conveyor belt) so as to extend away from the path of the second endless conveyor belt in the outfeed region. The path of the first endless conveyor belt may be inclined relative to the path of the second endless conveyor belt so as to approach the second endless conveyor belt along substantially the entire length of the infeed region and/or may be inclined relative to the path of the second endless conveyor belt so as to extend away from the second endless conveyor belt along substantially the entire length of the outfeed region.

The first and second endless conveyor belts each follow respective paths (which may be referred to as the first endless conveyor belt path and second endless conveyor belt path). Each such path is a continuous loop. The portions of the paths of the first and second endless conveyor belts referred to herein are portions of such paths.

The first and second endless conveyor belts form part of first and second conveyor assemblies. The first conveyor assembly may be located above the second conveyor assembly, and may be referred to as the upper conveyor assembly, and the second conveyor assembly as lower conveyor assembly herein.

The path of the first and second endless conveyor belts may be substantially linear in the machine direction through each of the infeed, compression and outfeed regions.

Alternatively or additionally the paths of the first and second endless conveyor belts are preferably straight throughout each of the infeed, compression and outfeed regions. In embodiments, a relative spacing e.g. a relative vertical spacing of the first and second endless conveyor belts changes only along the machine direction between the compression region and the outfeed region or optionally between the infeed region and the compression region.

Each one of the first and second conveyor assemblies further comprises a plurality of pulleys around which the respective one of the first and second endless conveyor belts travels when traversing its respective path. The plurality of pulleys of the respective conveyor assembly comprises at least one drive pulley for driving the respective one of the first and second endless conveyor belts along its path and at least one driven (or guide) pulley for guiding the conveyor belt as it travels along its path, and, in embodiments, each one of the first and second conveyor assemblies includes only one drive pulley and a plurality of driven (guide) pulleys. A guide pulley as used herein refers to a driven i.e. a non-drive pulley.

In embodiments, the first endless conveyor belt forms part of a first conveyor assembly, the first conveyor assembly further comprising a plurality of pulleys around which the first endless conveyor travels when traversing the first endless conveyor belt path, and the second endless conveyor belt forms part of a second conveyor assembly, the second conveyor assembly further comprising a plurality of pulleys around which the second endless conveyor belt travels as it traverses the second endless conveyor belt path. The apparatus further comprises a driving arrangement for driving the first and second endless conveyor belts along their respective paths. The pulleys of the first and second conveyor assemblies provide suitable tensioning and directing of the respective belts as they travel around their paths. The plurality of pulleys of the first conveyor assembly comprise at least one drive pulley and at least one driven pulley. The plurality of pulleys of the second conveyor assembly comprise at least one drive pulley and at least one driven pulley. The plurality of pulleys of the first conveyor assembly do not form part of the second conveyor assembly and vice versa i.e. the pulleys are not common to both conveyor assemblies, and provide distinct sets of pulleys. The pulleys of each conveyor assembly may be aligned with their axes along the cross machine direction.

Each conveyor assembly may, in some exemplary embodiments, respectively include a single drive pulley and a plurality of driven pulleys. Each one of the drive and driven pulleys of the first and second conveyor assemblies may extend in the cross direction. Each conveyor assembly may further comprise a frame. The apparatus may further comprise a support locating the first and second conveyor assemblies relative to one another.

Any suitable configuration of pulleys may be used (and of driven or guide and drive pulleys) in each of the first and second conveyor assemblies to provide suitable tensioning and driving of the respective belts in use. While the function and position of certain pulleys of the first and second conveyor assemblies and/or pulleys around which ones of the belts travel will be described in relation to certain embodiments herein, it will be appreciated that, unless otherwise stated, additional pulleys may be present, which may not be explicitly described.

In use, the first and second conveyor assemblies are driven in opposite directions such that the first and second endless conveyor belts each travel in the machine direction through the infeed, compression and outfeed regions i.e. in the opposed portions of the paths of the belts defining these regions.

The path of the first endless conveyor belt through the substantially entire length of the outfeed region may define a single plane and/or the path of the first endless conveyor belt through the substantially the entire length of the infeed region may define a single plane and/or the path of the first endless conveyor belt through the substantially entire length of the compression region may define a single plane. The path of the first endless conveyor belt through substantially the entire length of the outfeed region be linear along the machine direction and/or the path of the first endless conveyor belt through substantially the entire length of the infeed region may be linear along the machine direction and/or the path of the first endless conveyor belt through substantially the entire length of the compression region may be linear along the machine direction. Thus, preferably there are no changes of direction of the first endless conveyor belt within the infeed, compression and/or outfeed regions. As mentioned above, there may be a smooth transition between the regions, over a small distance e.g. corresponding to the path of the belt around a pulley. However, the paths of the belt in the respective regions may still be considered to define a single plane, or, in embodiments define a linear path. It will be appreciated that the convergence or divergence of the paths described herein in the outfeed or infeed regions is not merely provided by a portion of the path of a belt in which the belt travels around a pulley in order to change the direction of the belt.

In some embodiments the first and second endless conveyor belt paths define respective loop shapes having interior angles which are all less than 180 degrees. The loop shapes may have no points of inflection. The path of each one of the first and second endless conveyor belts may include an outward portion comprising the infeed, compression and outfeed regions, and a return portion connecting the downstream end of the outfeed region to the upstream end of the infeed region.

References to a path of a conveyor belt, or a portion thereof, or of the conveyor belt defining a plane, or single plane herein, refer to the general plane defined by the direction of the path or belt, and do not exclude the possibility of the belts having some surface undulations. A plane defined by either one of the first and second endless conveyor belts, or the direction of a path or a portion of the path thereof, where referred to herein, may be taken to be the plane or direction defined by the applicable portion of the stack facing (or outer) surface of the belt.

The apparatus may comprise any suitable arrangement to exert a compression force on stacks of articles passing through the compression region. For example, opposed "plates" may be arranged on either side of the of the first and second endless conveyor belts to contact the respective inner (pulley facing) surfaces of the belts in the compression region. However, preferably the first conveyor assembly comprises a first set of compression region pulleys and the second conveyor assembly comprises a second set of compression region pulleys, the first and second sets of compression region pulleys being arranged to guide the first and second endless conveyor belts respectively in the compression region and provide a compression force on stacks of articles passing through the compression region, wherein each one of the first and second sets of compression region pulleys comprises a plurality of pulleys spaced along machine direction. Each set of compression region pulleys contacts the inner (pulley facing surface) of the respective belt. The use of pulleys rather than "plates" has been found to reduce the wear and levels of heat generated in use for a given belt speed and compression load. Furthermore, the use of pulleys has been found to provide some calendaring effect on the articles in a stack as it passes through the compression region. This may be particularly advantageous in the context of a stack of articles such as tissue paper products, imparting the articles with improved surface properties e.g. softness. In some embodiments the compression region is free from compression plates.

Each pulley of the first set of compression region pulleys and each pulley of the second set of compression region pulleys extends in the cross machine direction. Each pulley in a respective one of the sets of compression region pulleys may be arranged so as to tangentially contact the first endless conveyor belt at the same level e.g. height.

In some embodiments the axes of the pulleys in each one of the pair of pulleys from the first and second sets of compression region pulleys are aligned with one another along the machine direction (e.g. lie one above the other), such that the first and second sets of compression region pulleys define a plurality of pairs of opposed pulleys along the machine direction. Each one of the first and second set of compression region pulleys may then include the same number of pulleys. Each pulley may then form part of an opposed pair of compression region pulleys. However, in other embodiments, it is envisaged that the sets of compression region pulleys may include different numbers of pulleys and/or axes of the pulleys within the sets could be offset from one another. The diameters of the pulleys in each set of compression region pulleys may vary. For example, in some embodiments, the upstream-most and downstream-most pulleys may have a greater diameter than one or more intermediate pulleys along the machine direction. As discussed below, this may enable the upstream-most and downstream-most pulleys of the first set of compression region pulleys (of the first conveyor assembly) to more gradually change the direction of the path of the first endless conveyor belt where these pulleys respectively define the end of the infeed region and the start of the outfeed region, helping to reduce risk of damage to stacks of articles. Where pulleys of different diameters are included in one of the first and second sets of compression region pulleys, the axes of the pulleys may be arranged at different levels to ensure that the pulleys tangentially contact the first endless conveyor belt at the same level i.e. height. In embodiments, opposed pairs of pulleys from the first and second sets of compression region pulleys have the same diameters.

In some embodiments, each one of the first and second sets of compression region pulleys comprises three or more pulleys. In these embodiments, the first and second sets of compression region pulleys may define upstream-most and downstream-most pairs of opposed pulleys and one or more intermediate pairs of opposed pulleys. In these embodiments the axes of respective ones of the opposed pairs of pulleys from the first and second sets of compression region pulleys are preferably aligned with one another e.g. lie one above the other. Optionally the upstream-most and downstream-most pairs of opposed pulleys have a greater diameter than the one or more intermediate pairs of opposed pulleys.

Optionally the upstream-most and downstream-most pulleys of the first set of compression region pulleys respectively define the end of the infeed region and the start of the outfeed region respectively. In some exemplary embodiments, each one of the first and second sets of compression region pulleys is a set of three pulleys. In some exemplary embodiments, the pulleys of the upstream-most pair of opposed pulleys and the downstream-most pair of opposed pulleys may have an outermost diameter of at least about 100mm, preferably at least about 130 mm. The outermost diameter of the upstream-most and down-stream-most pairs of opposed pulleys may be less than about 200mm, preferably less than about 150mm. The pulleys of the one or more intermediate pairs of opposed pulleys may have an outermost diameter of less than about 100mm, preferably less than about 85mm. The pulleys of the one or more intermediate pairs of pulleys may have an outermost diameter of greater than about 50mm, preferably greater than about 75 mm.

The diameter of a pulley herein refers to the outermost diameter of the pulley in the belt-contacting region of the pulley.

It has been found that the number, diameter and pitch (i.e. spacing between the axes of the pulleys in the machine direction) of the pulleys in the first and second sets of compression region pulleys may be selected as desired to optimise compression obtained in relation to a particular type and configuration of a stack of articles. These factors may be considered in conjunction with parameters including compression gap size and compression region length to obtain desired compression of a stack of articles. The pulleys of the first and second sets of compression region pulleys may be guide pulleys i.e. driven pulleys.

The infeed region may start at the upstream-most point of a length in the machine direction along which the first and second endless conveyor belts or the paths defined thereby are opposed i.e. face one another, and the outfeed region may terminate at the -21 -downstream-most point of a length along which the first and second endless conveyor belts or the paths defined thereby are opposed i.e. face on another. Thus, the infeed, compression and outfeed regions may occupy an entirety of a length along which the first and second endless conveyor belts (or the paths defined by the belts) are opposed.

The infeed region and/or the length in the machine direction along which the first and second endless conveyor belts are opposed may start at an upstream-most pulley of the first conveyor assembly. A length of the infeed region along the machine direction may be defined as starting from an axis of the upstream-most pulley. The upstream-most pulley of the first conveyor assembly may define the end of a return portion of the path of the first endless conveyor belt. The outfeed region and/or the length in the machine direction along which the first and second endless conveyor belts are opposed may terminate at a downstream-most pulley of the first conveyor assembly. A length of the outfeed region along the machine direction may be defined as ending at an axis of the down-stream most pulley. The down-stream most pulley may define the start of a return part of the path of the first endless conveyor belt.

Preferably the outfeed region extends between a first outfeed region pulley and a second outfeed region pulley, wherein the second outfeed region pulley is a downstream-most pulley of the first conveyor assembly, and the first outfeed region pulley is a further pulley of the first conveyor assembly upstream thereof The outfeed region ends at the second outfeed region pulley, and starts at the first outfeed region pulley. The length of the outfeed region may be defined as the distance between the axes of the first and second outfeed region pulleys along the machine direction. The first and second outfeed region pulleys are additional to the first and second infeed region pulleys, in those embodiments in which the infeed region includes such pulleys.

The second outfeed region pulley of the first conveyor assembly is a pulley around which the first endless conveyor belt tums at the end of the portion of its path in which it is opposed to i.e. faces the second endless conveyor belt to no longer oppose i.e. face the second endless conveyor belt. The second outfeed region pulley may change the direction of travel of the first endless conveyor belt from the machine direction while facing the second endless conveyor belt to a direction opposite the machine direction while facing away from the second endless conveyor belt. Thus the first endless conveyor belt commences a return portion of its path at the second outfeed region pulley. It will be seen that the first endless conveyor belt thus does not immediately begin its return path after the compression region, but instead continues along the machine direction through the tapered outfeed region, providing for a gradual reduction in the compression force experienced by stacks of articles, and guidance of the stack for a period after the stack has left the compression region. This may reduce the likelihood of damage e.g. to uppermost article(s) in the stack, reducing the tendency of the article(s) to stick to the first endless conveyor belt, and reducing the likelihood of distortion of the stack e.g. through "rhombussing".

The path of the second endless conveyor belt may extend beyond the second outfeed region pulley of the first conveyor assembly in the downstream direction to transmit onward stacks of articles supported thereon, but this portion, in which the second endless conveyor belt does not oppose i.e. face the first endless conveyor belt does not form part of the outfeed region. In embodiments in which the first and second conveyor assemblies comprise respective first and second sets of compression region pulleys, the first outfeed region pulley may also provide a downstream-most pulley of the first set of compression region pulleys. Thus, the first outfeed region pulley may define the end of the compression region (along the machine direction). A length of the compression region along the machine direction may be defined as ending at an axis of the first outfeed region pulley. There may be one or more intermediate pulleys for guiding the first endless conveyor belt between the first and second outfeed region pulleys, although, optionally, no such intermediate pulleys are provided. Where such pulleys are provided they should not cause any deviation in the path of the first endless conveyor belt. This enables the first and second outfeed region pulleys to define the path of the first endless conveyor belt in the outfeed region e.g. such that the path of the first endless conveyor belt defines a single plane between the first and second outfeed region pulleys. The path of the first endless conveyor belt may thus define a linear path between the first and second outfeed region pulleys.

In accordance with the invention, the first and second endless conveyor belts diverge in the outfeed region to provide a tapered outfeed. This may be achieved through suitable positioning of the first and second outfeed region pulleys of the of the first conveyor assembly between which the outfeed region is defined. The first and second outfeed region pulleys are located at different levels (i.e. in the vertical direction) to incline the path of the first endless conveyor belt relative to the path of the second endless conveyor belt e.g. with the second outfeed region pulley located above the first outfeed region pulley.

In embodiments in which the outfeed angle is variable, the relative positions of the first and second outfeed region pulleys of the first conveyor assembly may be variable to enable the outfeed angle to be changed. In embodiments, the position of the first outfeed region pulley is fixed, and the position of the second outfeed region pulley is variable in relation thereto to enable the outfeed angle to be varied. In some preferred embodiments, the second outfeed region pulley is slidably mounted to enable to vary the position of the first outfeed region pulley and provide a variable outfeed angle. For example, the second outfeed region pulley may be mounted on a slidable body e.g. plate. The slidable movement e.g. of a plate may be relative to a portion of a frame of the apparatus. However, other arrangements may be used which enable suitable movement of the second outfeed region pulley relative to the first outfeed region pulley. For example, the second outfeed region pulley may be mounted to a pivotable arm. The second outfeed region pulley may be mounted so as to permit vertical, and optionally only vertical movement of the pulley relative to the first outfeed region pulley. The second outfeed region pulley may be moveable towards and away from the second endless conveyor belt in order to provide the variable outfeed angle. Movement of the second outfeed region pulley may be accomplished manually, e.g. by unlocking and repositioning the pulley, or using a suitable automatic adjustment e.g. based upon parameters input by a user. An automatic adjustment may be based upon one or more control signals sent by a controller of the apparatus.

The apparatus may be configured such that variation of the outfeed angle e.g. movement of the second outfeed region pulley is possible only when the first and second endless conveyor belts are not running.

The second outfeed region pulley of the first conveyor assembly i.e. the downstream-most pulley thereof may be a drive pulley. The first outfeed region pulley may be a driven pulley. However, other arrangements of drive and driven pulleys may be used.

Preferably the infeed region extends between a first infeed region pulley and a second infeed region pulley, wherein the first infeed region pulley is an upstream-most pulley of the first conveyor assembly and the second infeed region pulley is a further pulley of the first conveyor assembly downstream of the first infeed region pulley. The infeed region starts at the first infeed region pulley, and ends at the second infeed region pulley.

The length of the infeed region may be defined as the distance between the axes of the first and second infeed region pulleys along the machine direction. The first infeed region pulley of the first conveyor assembly is a pulley around which the first endless conveyor belt turns in order to commence an outward portion of the path of the first endless conveyor belt in which it opposes i.e. faces the second endless conveyor belt. The first infeed region pulley changes the direction of travel of the first endless conveyor belt from a direction opposite the machine direction while facing away from the second endless conveyor belt to the machine direction while facing toward the second endless conveyor belt. The path of the second endless conveyor belt may extend beyond the first infeed region pulley of the first conveyor assembly in the upstream direction for receiving stacks of articles e.g. from an infeed conveyor belt, but this portion, in which the second endless conveyor belt does not oppose i.e. face the first endless conveyor belt does not form part of the infeed region. In embodiments in which the first and second conveyor assemblies comprise respective first and second sets of compression region pulleys, the second infeed region pulley preferably also provides an upstream-most pulley of the first set of compression region pulleys. Thus, the second infeed region pulley may define the start of the compression region (along the machine direction). A length of the compression region along the machine direction may be defined as starting at an axis of the second infeed region pulley. There may be one or more intermediate pulleys for guiding the first endless conveyor belt between the first and second infeed region pulleys. However, where such pulleys are provided they do not cause any deviation in the path of the first endless conveyor belt. This enables the first and second infeed region pulleys to define the path of the first endless conveyor belt e.g. such that the path of the first endless conveyor belt defines a single plane between the first and second infeed region pulleys. The path of the first endless conveyor belt may thus be linear between the first and second infeed region pulleys.

In some embodiments the path of the first endless conveyor belt wraps around the downstream-most pulley of the outfeed region (i.e. the second outfeed region pulley) so as to define a wrap angle of at least 90 degrees, or at least 135 degrees. The wrap angle may be less than 180 degrees. The path of the first endless conveyor belt may wrap around the upstream-most pulley of the infeed region (i.e. the first infeed region pulley) so as to define a wrap angle of at least 90 degrees or at least 135 degrees. The wrap angle may be less than 180 degrees.

Alternatively or additionally the path of the first endless conveyor belt may wrap around the second infeed region pulley and/or the first outfeed region pulley (which may correspond to a downstream-most and upstream most pulley of the compression region respectively) so as to define a wrap an angle of less than 120 degrees. The wrap angle is optionally less than 90 degrees, less than 60 degrees or less than 45 degrees.

A wrap angle as used herein refers to the angle subtended between the points on the circumference of the pulley defining the start and the end respectively of a section of the circumference of the pulley along which the belt contacts the pulley surface.

The first infeed region pulley of the first conveyor assembly may be a driven pulley. The second infeed region pulley may be a driven pulley. However, other arrangements of drive and driven pulleys may be used.

In preferred embodiments in which the first and second endless conveyor belts converge in the infeed region i.e. in which a tapered infeed is provided, this may be achieved through suitable positioning of the first and second infeed region pulleys of the first conveyor assembly. The first and second infeed region pulleys may be located at different levels (i.e. in the vertical direction) to incline the path of the first endless conveyor belt relative to the path of the second endless conveyor belt e.g. with the first infeed region pulley located above the second infeed region pulley.

In embodiments in which the infeed angle is variable, the relative positions of the first and second infeed region pulleys of the first conveyor assembly may be variable to enable the infeed angle to be changed. In embodiments, the position of the second infeed region pulley is fixed, and the position of the first infeed region pulley is variable in relation thereto to enable the infeed angle to be varied. In some preferred embodiments, the first infeed region pulley is mounted to an upstream end of a pivotable arm, which arm is pivotable about a pivot point in order to vary the position of the first infeed region pulley and provide a variable infeed angle. The upstream end of the arm thus corresponds to a distal end of the arm. In embodiments, the pivot point corresponds to an axis of the second infeed region pulley. This allows the arm to provide movement of the first infeed region pulley relative to the second infeed region pulley. However, other arrangements to provide suitable movement of the first infeed region pulley relative to the second infeed region pulley may be used e.g. a slidable body etc. Movement of the the first infeed region pulley may be accomplished manually, e.g. by unlocking and repositioning the arm, or using a suitable automatic adjustment e.g. based upon parameters input by a user. An automatic adjustment may be based upon one or more control signals sent by a controller of the apparatus.

The apparatus may be configured such that variation of the infeed angle e.g. movement of the pivotable arm is possible only when the machine is not running.

The length of the infeed region, and hence, in embodiments, the length of an arm connecting the first and second infeed region pulleys between which the infeed region is defined, may be selected as desired, and, in embodiments providing a converging infeed, to provide suitable gradual compression of a stack of articles in use. In general, a longer converging infeed may be associated with less distortion of a stack of articles, and hence improved stack stability. However, as the length of the infeed region increases, e.g. a length of the pivotable arm increases, in embodiments, this may start to introduce some instability in the infeed region i.e. in the ability to control the path of the first endless conveyor belt precisely.

The first and second infeed region pulleys of the first conveyor assembly may each be driven pulleys.

The position of a pulley e.g. an outfeed or infeed region pulley (or compression region pulley) may be defined by the position of the axis of the pulley unless the context demands otherwise.

Regardless of the configuration of the infeed, compression and outfeed regions, in embodiments in which the compression gap size is adjustable, this may be achieved in any suitable manner. In preferred embodiments, the position of the second conveyor assembly is fixed, and the first conveyor assembly is movable as a whole relative to the second conveyor assembly to vary the size of the compression gap. The first conveyor assembly is movable towards and away from the first conveyor assembly within a given range of movement to permit variation of the size of the compression gap. In embodiments the first conveyor assembly is slidably mounted relative to the second conveyor assembly to permit variation of the compression gap size. For example, a frame of the first conveyor assembly may be slidably mounted to a support e.g. a part of a frame of the apparatus to permit movement of the first conveyor assembly relative to the second conveyor assembly. This may be achieved using any suitable arrangement, such as rails. However, any suitable arrangement enabling relative movement between the conveyor assemblies may be used. The movement may be vertical movement, and, in embodiments, movement of the first conveyor assembly as a whole is possible only in a vertical direction. In these embodiments in which the first conveyor assembly is moveable as a whole, variation of the compression gap size may be achieved independently of variation of the infeed and/or outfeed angles. In embodiments the apparatus is arranged such that movement of the first conveyor assembly to permit variation of the compression gap size is possible only between runs of the apparatus.

Where the infeed angle, outfeed angle and/or compression gap size are variable, the apparatus may comprise an indicator indicative (directly or indirectly) of the value of the angle or size to provide feedback to a user. For example, a scale may be provided indicative of the position of any one of the components e.g. pulleys or conveyor assembly which is movable to facilitate adjustment of the apparatus to obtain a desired configuration.

In accordance with the invention in any of its embodiments, the apparatus further comprises a driving arrangement for driving the first and second endless conveyor belts of the first and second conveyor assemblies along their respective paths. Regardless of the type of driving arrangement used, in embodiments, the driving arrangement may be operable to drive each of the first and second endless conveyor belts at a speed greater than about 20m/min, or greater than 30m/min, optionally greater than about 40m/min, or optionally greater than about 50m/min in use for compressing stacks of articles. Thus, the apparatus may enable compression to be performed at relatively high speed. It has been found that the speed of operation of the conveyor belts may not have a significant impact on the properties of the resulting stacks of articles, and the speed may therefore be selected as desired for a particular process e.g. based on speeds of operation of upstream and/or downstream processes. It is believed that the improved stack properties may result from the ability to sandwich stacks of articles between the first and second endless conveyor belts through the compression region and at least a portion of the infeed region and outfeed region.

In some embodiments, a common driving arrangement may be provided for driving both the first and second endless conveyor belts i.e. such that the belts are not independently drivable. For example, a motor may be provided which is arranged to drive drive pulleys of both the first and second conveyor assemblies. This may have the advantage that the belts may be consistently driven at the same speed.

However, in other embodiments the first and second endless conveyor belts of the first and second conveyor assemblies are independently drivable, and the driving arrangement comprises first and second independently controllable driving arrangements for driving the first and second endless conveyor belts respectively. This may enable the speeds of the first and second endless conveyor belts to be independently controlled, providing the ability to provide a speed differential between the first and second endless conveyor belts.

Depending upon the properties of the resulting compressed stacks of articles, it may be appropriate in different circumstances to drive the first and second endless conveyor belts at the same or different speeds. For example, in some situations it may be desirable to provide a speed differential in order to counteract any "rhombusing" which may otherwise tend to occur within the stack. This may help to further optimise compression of the stacks of articles. The use of a speed differential or otherwise may be used to correct any defects noted in the resulting stacks of articles in a feedback type arrangement. The first and second driving arrangements may be associated with the first and second conveyor assemblies.

The first driving arrangement may comprise a first motor arranged to drive a drive pulley of the first conveyor assembly, and the second driving arrangement may comprise a second motor arranged to drive a drive pulley of the second conveyor assembly. In embodiments, one or both of the first and second driving arrangements are arranged to drive their respective endless conveyor belts at a target speed. The target speed may be transmitted by a controller of the apparatus to control circuitry of the driving arrangement. In some embodiments the first and second conveyor assemblies each include only one drive pulley. The drive pulleys may be the downstream-most pulleys of the respective conveyor assemblies.

The first and second motors may be of any suitable type e.g. AC motor of any type e.g. single phase or three-phase, or a DC motor of any type. In preferred embodiments one or preferably both of the first and second motors are servomotors. A servomotor may be located in any suitable manner provided that it is able to transmit movement to the drive pulley of the respective conveyor assembly. In some embodiments the servomotor is integral with the drive pulley. However, it is understood that other arrangements are possible.

A servomotor is a type of motor which operates in a closed loop control system to use feedback regarding a parameter of the motor's operation to control the parameter to a target value. A servomotor as used herein comprises a motor, sensing circuitry for sensing one or more parameters of the motor indicative of a speed of the motor e.g. a linear encoder, circuitry for comparing the speed of the motor to a target speed of the motor, and circuitry for controlling the speed of the motor based on the results of the comparison. The speed of the motor may be controlled directly or indirectly e.g. through control of the position of the motor etc. The one or more parameters indicative of the speed of the motor may be speed or any parameter(s) enabling speed to be determined e.g. position at different times, torque etc. The target speed of the motor may be set in order to achieve a given speed of the endless conveyor belt of the respective conveyor assembly with which the drive pulley driven by the servomotor is associated. The target speed of the motor may be a based on a target speed received from a controller of the apparatus for use by the servomotor in achieving a given speed of the endless conveyor belt. The received target speed may be a target belt speed or a target motor speed. Thus, in some embodiments, control circuitry of the servomotor may determine a target motor speed based upon a received target speed of the belt, or such a target motor speed may be determined by a controller of the apparatus and sent to the servomotor for use thereby.

It has been found that in some situations, the speed of a conveyor belt may not correspond to a target speed that has been set. The use of a servomotor enables the speed of the belt to be more precisely controlled based on the speed of the motor which is indicative of the actual speed of the belt. For example, in some cases, the motor may struggle under load momentarily during compression of a stack of articles. Over time, these momentary problems may cause the belt speed to be inconsistent and/or slow down. By using closed loop servomotors which may check their own actual speed, the motors may run more consistently at a target motor speed to provide a target speed of the belt, providing more consistent and precise control of belt speed. As the servomotors provide greater control over belt speed, they may enable the belts to be more reliably and consistently run at any given combination speeds, whether in an arrangement in which the belts are to be run at the same speed, or with a speed differential. It has also been found that a servomotor may provide greater torque capability than an induction motor, reducing the likelihood of the motor struggling under load.

The first and second endless conveyor belts may be of any suitable construction. Each conveyor belt may be continuous along a length and width thereof. The conveyor belts may be free from openings therethrough.

In embodiments each one of the first and second endless conveyor belts has an inner side and an outer side. The inner side (the "pulley facing side") faces toward the pulleys of the respective conveyor assembly in use. The inner side or surface may be referred to as the first side or surface of the belt herein. The outer side ("the stack facing side") faces toward stacks of articles conveyed between the first and second endless conveyor belts in use. The outer side or surface may be referred to as the second side or surface of the belt herein. The inner side defines an inner (pulley facing) surface adapted to engage surfaces of the pulleys of the respective conveyor assembly in use. The outer side defines an outer (stack facing) surface adapted to contact stacks of articles in use. At any time at least a portion of the inner surface will be in contact with the surfaces of pulleys of the conveyor assembly and at least a portion of the outer surface will be in contact with stacks of articles located between the first and second endless conveyor belts in use. Here, "inner' and "outer' are with respect to the loops defined by the path of a belt i.e. toward the inside or outside of that loop.

Various features may be used to ensure that the inner, pulley facing surface of a belt is able to grip the pulleys to a sufficient degree to adequately tension the belt, and enable levels of torque necessary to compress stacks of articles to be generated. However, improved grip between the pulleys will result in an increase in the amount of friction generated as the belt travels over the pulleys, and so the level of grip between the pulleys and belt should be balanced against the levels of friction generated. The following features are applicable to either one of, or more preferably both, of the first and second endless conveyor belts or one or preferably both of the first and second conveyor assemblies.

In some embodiments the inner side of the belt may comprise a plurality of cross machine direction oriented elongate teeth spaced at intervals along the length of the belt, wherein the teeth impart the inner surface of the belt with a pattern of alternating peaks and troughs along the length of the belt. The teeth may extend along the entire length of the belt. The teeth are arranged in a repeating pattern along the length of the belt. The teeth may be in the form of elongate ridges. Each tooth may extend across the entire width of the belt in the cross machine direction. In these embodiments at least some of the pulleys of the respective conveyor assembly of which the belt forms part are toothed pulleys, having axially oriented elongate teeth spaced at intervals around the circumference of the pulley, wherein the teeth impart the outer belt contacting surface of the pulley with a pattern of alternating peaks and troughs around the circumference of the pulley. The teeth may extend along the entire circumference of the pulley. The peaks and troughs are defined within a radial direction of the pulley. The teeth of the belt cooperate with the teeth of the or each toothed pulley of the conveyor assembly in order to provide suitable engagement between the pulley(s) and belt e.g. to transmit torque to the belt in use. At least some (i.e. one or more of), and optionally all of the pulleys of the conveyor assembly may be toothed. In some embodiments at least the pulleys of the compression region are toothed. It has been found that the use of a toothed belt which cooperates with toothed pulleys of the conveyor assembly may help to enable sufficient torque to be imparted to the belt to enable it to be used to compress stacks of articles effectively.

The teeth of the belt may define a regular pattern. In some exemplary embodiments, each tooth of the belt may have a height of from about 1mm to about 10mm, or optionally from about 2mm to about 5mm. The height of a tooth is measured from the level of the bottom of a valley to the level of the top of the tooth along a direction perpendicular to the lowest point of the valley. Thus the height is a shortest distance between the planes in which the bottoms of the valleys and the tops of the teeth lie. The teeth may be separated by a distance of from about 5mm to about 50mm, or optionally from about 5mm to about 10mm. The distance between the teeth corresponds to a pitch between the teeth, and is measured between corresponding points on adjacent teeth along the machine direction. The dimensions and/or spacing of the teeth of a pulley which cooperates with the belt may lie within any of the above ranges.

In use, the teeth of the belt nest between the teeth of the or each toothed pulley of the conveyor assembly with which the belt cooperates. It has been found that a toothed pulley may sometimes undesirably result in impressions or distortions being produced in the surface of a stack of articles being compressed when travelling on the belt over the pulley, particularly when such toothed pulleys are used in the compression region. Such surface distortions or impressions may be referred to as "castellations", and result from conditions in which the teeth of the pulleys engage the belt in a manner which results in the belt exhibiting protrusions on the stack facing, outer surface thereof, corresponding to the positions in which the teeth of the pulley engage the belt. The extent to which this effect may occur will depend upon various factors e.g. the pressures exterted, the rigidity of the belt etc. In embodiments, the belt is registered relative to a toothed pulley of the conveyor assembly (or relative to the or each such toothed pulley) such that the tops of respective ones of the teeth of the pulley contact the bottoms of respective ones of the valleys defined between the teeth of the belt. This feature is advantageously used at least in relation to one or more pulleys of the compression region. It has been found that, in this way, the bottoms of the valleys between the teeth of the belt may be supported by the tops of the teeth of the pulley. At least some, or all of the teeth of the pulley and belt may be registered in this way. In these embodiments the height of the teeth of the pulley preferably exceeds the height of the teeth of the belt such that the tops of respective ones of the teeth of the belt do not contact the bottoms of the valleys between respective ones of the teeth of the pulley. This has been found to improve support of the belt on the pulley and reduce the "castellation" effect in comparison to the case in which bottoms of the valleys of the pulley are contacted by the tops of the teeth of the belt (with the height of the teeth of the belt exceeding the height of the teeth of the pulley). The height of a tooth of a pulley or belt is the difference in level between the bottom of a valley adjacent the tooth and the level of the top of the tooth. The height is measured as a shortest distance. Thus, the height of a tooth is measured from the level of the bottom of a valley to the level of the top of the tooth along a direction perpendicular to the lowest point of the valley. Thus the height is a shortest distance between the planes in which the bottoms of the valleys and the tops of the teeth lie.

At least some of; the tops of the teeth of the belt, the tops of the teeth of the pulley, the bottoms of the valleys of the pulley and the bottoms of the valleys of the belt may be substantially flat. In other words, the tops of the teeth and/or the bottoms of the valleys are flattened i.e. not curved or pointed. In embodiments the belt is registered relative to a toothed pulley or pulleys of the conveyor assembly such that the tops of respective ones of the teeth of the pulley and/or belt contact the bottoms of respective ones of the valleys -31 -defined between the teeth of the other one of the pulley or belt, wherein those ones of the tops of the teeth and the bottoms of the valleys of the belt and pulley which contact one another are substantially flat.

In the preferred embodiments in which the tops of respective ones of the teeth of the pulley contact the bottoms of respective ones of the valleys defined between the teeth of the belt, the bottoms of the valleys of the belt and the tops of the teeth of the pulley are preferably substantially flat. This may provide a relatively large surface area of engagement between the teeth of the pulley and the valleys of the belt, helping to reduce further the occurrence of castellations. It is envisaged that in such embodiments the tops of the teeth of the belt and the bottoms of the valleys of the pulley may alternatively or additionally also be substantially flat. In some embodiments, the registration of the belt relative to the pulley may be the opposite of that described above. Thus, the belt may be registered relative to a toothed pulley of the conveyor assembly (or relative to the or each such toothed pulley) such that the tops of respective ones of the teeth of the belt contact the bottoms of respective ones of the valleys defined between the teeth of the pulley. At least some, or all of the teeth of the pulley and belt may be registered in this way. In these embodiments the height of the teeth of the belt may exceeds the height of the teeth of the pulley such that the tops of respective ones of the teeth of the pulley do not contact the bottoms of the valleys between respective ones of the teeth of the belt. In these embodiments, the tops of the teeth of the belt and the bottoms of the valleys of the pulley may be substantially flat. In yet other embodiments, the tops of the teeth of the belt and the bottoms of the valleys of the belt and the tops of the teeth of the pulley and the bottoms of the valleys of the pulley may all be substantially flat. This may be appropriate where the heights of the teeth of the pulley and the teeth of the belt are chosen such that the tops of the teeth of the belt contact the bottoms of the valleys between the teeth of the pulley and the tops of the teeth of the pulley contact the bottoms of the valleys between the teeth of the belt. However, any increase in the surface area of contact between the pulley and belt will need to be balanced against increased amounts of friction and wear on the belts.

The use of teeth on the inner, pulley facing surface of a belt is not essential, and other features may be used, if required, to facilitate gripping between the surface of the belt and a pulley. For example, a grained surface may be used, or some other form of surface feature which may increase the coefficient of friction of the surface.

The material of the first and second endless conveyor belts may be selected as desired. It has been found that the material providing the outer (stack facing) surface of the belt may be tailored to provide properties which reduce the risk of castellations occurring in the surfaces of articles in the compressed stacks of articles. The more rigid the belt, the less likely this effect is to occur. In some embodiments either one, or both of the first and second endless conveyor belts comprises a plurality of layers, including a base layer which provides the outer (stack facing) surface of the belt. This enables the properties of the base layer to be tailored more readily, as the properties of the base layer may be varied independently of another layer or layers of the belt (which may be separately tailored based on the functions they need to perform). The base layer may be laminated to a further layer defining teeth or other features to enhance engagement between the belt and pulleys as described in the earlier embodiments. The further layer may define the inner surface of the belt and may comprise a plurality of cross machine direction oriented elongate teeth which provide the inner surface with a pattern of alternating peaks and troughs along the length of the belt as previously described.

The base layer may be selected to provide a desired combination of strength, rigidity and/or hardness to facilitate compression of stacks without detrimentally affecting surface properties thereof. It has been found that a base layer with a relatively high Shore A hardness value may be useful in this regard, reducing the occurrence of castellations due to distortion of the belt when the inner surface thereof engages teeth of pulleys (where toothed pulleys are used). In embodiments the base layer has a Shore A hardness value of at least 40, or at least 50, or optionally in the range of from 50 to 80. In general, a belt layer defining an outer, stack facing side of the belt may have a Shore A hardness value of at least 40, or at least 50, or optionally in the range of from 50 to 80. These values are applicable whether the layer is one of a number of layers providing a belt having a laminate structure, or whether the belt is a single layer belt.

Alternatively or additionally, the outer, stack facing surface of a belt (or of the base layer thereof where the base layer defines the outer surface of the belt) is preferably substantially smooth. In such embodiments the outer surface is free from macroscopic surface features, such as protrusions or recesses (e.g. such as may be provided by surface embossments or openings in the surface). It is envisaged that the outer surface of the belt may still exhibit a fine (microscopic) grain structure, although, in some embodiments the belt is polished or machined to remove any visible grain structure. The use of a substantially smooth belt has been found to reduce the risk of articles from stacks tending to adhere to the surface of the belt. Such adherence is undesirable as it may lead to distortion or tearing of the surface of the articles. The use of a smooth belt surface may also reduce the build-up of residue from articles e.g. fibers etc. over lime, which may affect the consistency and reliability of the apparatus. The outer surface of the belt preferably has anti-static properties and/or comprises one or more release agents to inhibit adherence between articles from the stacks and the belt. The material of the outer surface of the belt is preferably continuous i.e. free from openings therethrough.

Either one, or optionally both of the first and second endless conveyor belts may have any of the properties above described.

It is envisaged that the pulleys which change the direction of the belt(s) as described herein e.g. the first and second infeed region pulleys or the first and second outfeed region pulleys, may be of relatively large diameter to enable changes in the direction of the path of the belt to be achieved without excessive bending of the belt, even where the belt is relatively rigid, as in the preferred embodiments described. The diameter of these pulleys may be large in comparison to other pulleys of the respective conveyor assembly which are not required to redirect a belt.

The apparatus described herein in any of its aspects or embodiments may form part of a system. The system may comprise any additional components upstream or downstream thereof e.g. to obtain the stacks of articles to be compressed, and/or to perform further operations upon the stacks of articles once compressed. The system may also comprise additional components required to result in operation of the apparatus as herein described. For example, the system may comprise a controller for controlling the operation of the apparatus. This may be achieved in any suitable manner e.g. using wired and/or wireless transmissions. The controller may be arranged to control the operation of the apparatus in accordance with a set of operating parameters. At least some of the operating parameters may be user specified. The set of operating parameters may include target speeds of the first and second endless conveyor belts. The target speeds may be the same or different.

In some embodiments the system further comprises an infeed endless conveyor belt for supplying stacks of articles to be compressed to the infeed region of the apparatus and/or an outfeed endless conveyor belt for receiving compressed stacks of articles from the outfeed region of the apparatus. The infeed and outfeed endless conveyor belts may form part of respective infeed and outfeed conveyor assemblies. Such assemblies may comprise additional components as described in relation to the first and second conveyor assemblies. The infeed and outfeed conveyor assemblies each further comprise a set of a plurality of pulleys around which the infeed or outfeed conveyor respectively travels along its respective infeed or outfeed endless conveyor belt path. The respective sets of pulleys include at least one drive pulley for driving the infeed or outfeed endless conveyor belt as appropriate and at least one guide (or driven) pulley. The system may further comprise a driving arrangement for driving the infeed and outfeed endless conveyor belts along their respective paths. The driving arrangements may be of any suitable type.

In contrast to the first and second endless conveyor belts associated with the first and second conveyor assemblies of the compression apparatus, which advantageously comprise teeth on a pulley facing surface thereof for cooperating with teeth of the pulleys of the first or second conveyor assemblies as appropriate, the infeed and outfeed endless conveyor belts and the pulleys of the infeed and outfeed conveyor assemblies may be smooth i.e. do not comprise teeth. As stacks of articles are not compressed when travelling along the infeed or outfeed conveyors, it is not necessary to generate such high levels of torque when driving the belts. The infeed and outfeed conveyor belts may also be thinner than the conveyor belts of the first and second conveyor assemblies.

Any suitable interface may be provided between an infeed endless conveyor belt and the infeed region of the apparatus. In embodiments the infeed endless conveyor belt is arranged to supply stacks of articles to be compressed to the second endless conveyor belt. The stacks of articles may then be supported by the second endless conveyor belt as they pass through the infeed, compression and outfeed regions. A downstream-most end of the path of the infeed endless conveyor belt may be arranged such that it is at a level above an upstream-most end of the path of the second endless conveyor belt. This may result in stacks of articles experiencing a drop on to the second endless conveyor belt. The downstream-most end of the infeed conveyor belt may correspond to a downstream-most end of the infeed conveyor assembly. This may be defined by the position of a downstream-most pulley of the infeed conveyor assembly about which the infeed endless conveyor belt turns. The upstream-most end of the second endless conveyor belt may correspond to an upstream-most end of the second conveyor assembly.

The downstream-most end of the path of the infeed endless conveyor belt should be located appropriately with respect to the upstream-most end of the path of the second endless conveyor belt to enable stacks of articles to be readily transferred therebetween, without detrimentally affecting stack stability. In some embodiments a plate (which may be referred to as a "dead" plate) may be provided between the downstream-most end of the path of the infeed endless conveyor belt and an upstream-most end of the second endless conveyor belt. The downstream-most end of the path of the infeed endless conveyor belt may be defined by the position of a downstream-most pulley of the infeed conveyor assembly, and the upstream-most end of the path of the second endless conveyor belt may be defined by the position of an upstream-most pulley of the second endless conveyor assembly. It has been found that in embodiments of the invention, the upstream-most pulley of the second conveyor assembly may be of relatively large diameter to avoid excessive bending of the second endless conveyor belt around the pulley, in particular where a relatively rigid conveyor belt is used. This may result in a relatively large gap to be bridged between the second endless conveyor belt and the infeed endless conveyor belt. In preferred embodiments a nose pulley is provided at a downstream-most end of the infeed conveyor assembly about which the infeed endless conveyor belt turns at the downstream-most end of its path to facilitate transfer of stacks of articles from the infeed endless conveyor belt to the second endless conveyor belt. The nose pulley may have a diameter that is significantly smaller than a diameter of the upstream-most pulley of the second conveyor assembly about which the second endless conveyor belt turns at the upstream-most end of its path. For example, the ratio of the diameter of the nose pulley to the diameter of the upstream-most pulley of the second conveyor assembly may be from about 0.01 to about 0.3, or optionally from about 0.05 to about 0.2. The axis of the nose pulley may be located above the axis of the upstream-most pulley of the second endless conveyor belt. It has been found that the use of a nose pulley in this way may provide advantages in the ability to transfer stacks of articles between the infeed conveyor and the second endless conveyor belt without detriment to stack stability, and may provide an improvement over the use of dead plates. This is particularly important in the context of transferring unpackaged i.e. naked stacks. Dead plates result in an area without drive. If such an area is relatively large with respect to the footprint of stacks of articles being transferred the ability to transfer the stacks effectively without affecting stack stability may be impaired.

Alternatively or additionally, any suitable interface may be provided between an outfeed endless conveyor belt and the outfeed region of the apparatus. In embodiments the outfeed endless conveyor belt is arranged to receive compressed stacks of articles from the second endless conveyor belt. An upstream end of the path of the outfeed endlesss conveyor belt may be arranged such that it is at a level below a downstream end of the path of the second endless conveyor belt. This may result in stacks of articles experiencing a drop on to the outfeed endless conveyor belt. The upstream end of the outfeed conveyor belt may correspond to an upstream end of the outfeed conveyor assembly. This may be defined by the position of an upstream-most pulley of the outfeed conveyor assembly about which the outfeed endless conveyor belt turns. The downstream-most end of the second endless conveyor belt may correspond to a downstream-most end of the second conveyor assembly. This may be defined by the position of a downstream-most pulley of the second conveyor assembly about which the second endless conveyor belt turns.

The upstream-most end of the path of the outfeed endless conveyor belt should be located appropriately with respect to the downstream-most end of the path of the second endless conveyor belt to enable stacks of articles to be readily transferred therebetween, without detrimentally affecting stack stability. In some embodiments a plate (which may be referred to as a "dead" plate) may be provided between the upstream-most end of the path of the outfeed endless conveyor belt and a downstream-most end of the second endless conveyor belt. The upstream-most end of the path of the outfeed endless conveyor belt may be defined by the position of an upstream-most pulley of the outfeed conveyor assembly, and the downstream-most end of the path of the second endless conveyor belt may be defined by the position of a downstream-most pulley of the second endless conveyor assembly. It has been found that in embodiments of the invention, the downstream-most pulley of the second conveyor assembly may be of relatively large diameter to avoid excessive bending of the second endless conveyor belt around the pulley, in particular where a relatively rigid conveyor belt is used. This may result in a relatively large gap to be bridged between the second endless conveyor belt and the outfeed endless conveyor belt.

In preferred embodiments a nose pulley is provided at an upstream-most end of the outfeed conveyor assembly about which the outfeed endless conveyor belt turns at the upstream-most end of its path to facilitate transfer of stacks of articles to the outfeed endless conveyor belt from the second endless conveyor belt. The nose pulley may have a diameter that is significantly smaller than a diameter of the downstream-most pulley of the second conveyor assembly about which the second endless conveyor belt turns at the downstream-most end of its path. For example, the ratio of the diameter of the nose pulley to the diameter of the downstream-most pulley of the second conveyor assembly may be from about 0.01 to about 0.3, or optionally from about 0.05 to about 0.2. The axis of the nose pulley may be located above the axis of the downstream-most pulley of the second endless conveyor belt. It has been found that the use of a nose pulley in this way may provide advantages in the ability to transfer stacks of articles between the outfeed conveyor and the second endless conveyor belt without detriment to stack stability, and may provide an improvement over the use of dead plates. This is particularly important in the context of transferring unpackaged i.e. naked stacks. Dead plates result in an area without drive. If such an area is relatively large with respect to the footprint of stacks of articles being transferred the ability to transfer the stacks effectively without affecting stack stability may be impaired.

While in some embodiments the use of a nose roller may avoid the need for any dead plate to be used at the interface between an infeed conveyor belt and the second endless conveyor belt, and/or between an outfeed conveyor belt and the second endless conveyor belt, it is envisaged that a smaller dead plate could still be used in conjunction with a nose pulley to bridge any remaining gap, particularly at the infeed, where pre-compressed stacks may have less stability than the post-compressed stacks at the outfeed. However, the use of such a dead plate is not essential.

The system may comprise a packaging unit downstream of the outfeed region. In embodiments in which an outfeed endless conveyor belt is provided, the packaging unit is downstream of the outfeed endless conveyor belt. The packaging unit may be arranged to automatically pack the compressed stacks of articles. For example, the outfeed endless conveyor belt may arranged to supply compressed stacks of articles from the outfeed region of the apparatus to the packaging unit. However, any suitable intermediate arrangement may be used to deliver compressed stacks of articles from the outfeed region to the packaging unit. The packaging unit may be configured to insert the compressed stacks of articles into any suitable form of package. In embodiments the package is a rigid container, such as a box. The container may be a carton. The container may be constructed from any rigid materials, for example, cardboard, carton stock, paper board, polypropylene, polyethylene, polystyrene, ABS plastic, plastic, metal, wood, and glass amongst other suitable alternatives. In embodiments the container is a paperboard or cardboard container. In some embodiments the container is a non-plastic container. In other embodiments, rather than using an automated packaging unit, it is envisaged that packing of the compressed stacks of articles e.g. onto containers may be performed manually. A carton, whatever its material, may be of any desired shape, although in embodiments is square or rectangular.

In embodiments no packaging of the stack of articles occurs before or during compression of the stacks of articles in the compression apparatus.

It is envisaged that multiple sets of the compression apparatus described herein may operate in parallel e.g. to provide multiple lanes for compressing stacks of articles. Each set of apparatus may be of the same construction.

Any one or ones of the pulleys of the first and second conveyor belt assemblies about which the respective belt changes direction may, in some exemplary embodiments, have an outermost diameter of at least about 100mm, or at least about 130 mm. The outermost diameter of the pulleys may be less than about 200mm, or less than about 150mm. Such pulleys include the pulleys at the upstream and downstream most ends of the compression region, or the upstream most and downstream most pulleys of the conveyor assemblies. Pulleys which do not provide a change in direction of a belt e.g. which just provide a support function, may, in some exemplary embodiments, have an outermost diameter of less than about 100mm, or less than about 85mm. The pulleys may have an outermost diameter of greater than about 50mm, preferably greater than about 75 mm. The outermost diameter refers to the outermost diameter of a belt contacting portion of the pulleys. The above ranges are only exemplary. In some embodiments, in general, any one or ones or each of the pulleys of the first and second conveyor belt assemblies about which the respective belt changes direction may have a greater outer diameter than pulleys which do not provide a change in direction of a belt e.g. which just provide a support function.

The present invention extends to a method of automatically compressing stacks of articles using the apparatus or system in accordance with any of the aspects or embodiments of the invention herein described. The method may comprise supplying stacks of articles to be compressed to the infeed region of the apparatus; and operating the apparatus such the stacks of articles are conveyed along a path in the machine direction sequentially through the infeed region, compression region and outfeed region; optionally wherein the stacks of articles are unpackaged articles.

The method in these further aspects or embodiments may extend to a step of operating the apparatus in accordance with any of the above described features of the embodiments where not explicitly stated and the apparatus or system comprising the apparatus as appropriate may be configured to enable any of the steps of the method to be performed, where not explicitly stated.

The stacks of articles which are compressed according to the methods described herein, or which may be compressed by the apparatus or systems described herein, may be of any suitable type.

The stacks of articles that undergo compression herein are preferably unpackaged stacks of articles. Unpackaged stacks of articles as used herein are stacks of articles which are free from any outer packaging, whether partially or fully surrounding the stack to assist in retaining the articles in their stacked configuration. Such outer packaging encompasses any components such as a band or sleeve used for the purposes of retaining the stack in its stacked configuration prior to final packaging (and which may not necessarily form part an outer packaging of a packaged stack in its final form e.g. they may be removed or remain within a final outer package). Thus, the stacks of articles are free from outer packaging, including such packaging which does not form the outer packaging of the stacks of articles in their final package. The stacks of articles are free from additional e.g. external components to assist in retaining the articles in their stacked configuration. The articles within the stack are therefore free to move relative to one another to at least some degree. The articles may be referred to as "loose". In some embodiments the articles are not connected to one another, while in other embodiments the articles may be joined to one another within the stack without the aid of additional components, e.g. using interfolding or perforations.

It is believed that the use of a diverging belt outfeed when compressing unpackaged stacks of articles is advantageous in its own right. As described above, this may help to reduce the occurrence of certain problems which may otherwise tend to occur in the context of unpackaged stacks of articles, e.g. surface damage and/or stack stability issues.

In accordance with a further aspect of the invention there is provided; a method of compressing unpackaged stacks of articles using an automated apparatus for compressing stacks of articles, wherein the apparatus defines an infeed region, a compression region and an outfeed region, and is arranged to convey stacks of articles along a path in a machine direction in use sequentially through the infeed region, compression region and outfeed region, wherein the apparatus comprises one or more endless conveyor belts on one side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region and one or more endless conveyor belts on an opposite side of the path along which the stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region; the method comprising; supplying stacks of articles to be compressed to the infeed region of the apparatus; and operating the apparatus such that the stacks of articles are conveyed along a path in the machine direction sequentially through the infeed region, compression region and outfeed region; wherein the infeed region, compression region and outfeed region of the apparatus are each defined between respective opposed portions of the paths of ones of the conveyor belts on either side of the path along which the stacks move through the infeed region, compression region and outfeed region in the machine direction, wherein the opposed portions of the paths of the conveyor belts defining the outfeed region diverge from one another along the machine direction.

The present invention in this further aspect may include any or all of the features described in relation to the earlier aspects and embodiments of the invention to the extent they are not mutually exclusive.

Each one of the endless conveyor belts may travel along a respective endless conveyor belt path in the form of a continuous loop. Each such path may comprise an outward portion and a return portion. Each conveyor belt travels round a respective set of pulleys. The pulleys include at least one drive pulley and at least one driven pulley. In this further aspect, it is envisaged that, rather than being provided between opposed portions of the paths of the same pair of endless conveyor belts e.g. the first and second endless conveyor belts of the earlier embodiments, the infeed, compression and outfeed regions may each be provided between opposed portions of the paths of any one of one or more endless conveyor belts disposed on one side of the path of the stacks of articles and any one of one or more endless conveyor belts disposed on the other (opposite) side of the path. A single one of the one or more endless conveyor belts on one side of the path of the stacks of articles may provide one of the opposed conveyor belt path portions for providing one or more of the infeed, compression and outfeed regions, with one or more of the endless conveyor belts on the other side of the path of the stacks of articles. For example, each one of the infeed, compression and outfeed regions might be defined between opposed portions of the paths of a respective opposed pair of conveyor belts, such that different pairs of conveyor belts define different ones of the infeed, compression and outfeed regions. Alternatively, a given pair of opposed conveyor belts may define two of the infeed, compression and outfeed regions, with a further pair of belts defining the further region. One or more conveyor belts on one side of the path of the stacks of articles may cooperate with a different number of conveyor belts on the other side of the path of the stacks of articles in order to define the infeed, compression and outfeed regions. For example, a single conveyor belt on one side of the path e.g. a lower path may define one of the opposed path portions of each of the infeed, compression and outfeed regions, with the other ones of the opposed conveyor belt path portions being provided by multiple conveyor belts on the other side of the path. In general, the opposed conveyor belt path portions may be provided by any combination of; one, two or three conveyor belts on one side of the path of the stacks of articles with one, two or three conveyor belts on the other side of the path of the stacks of articles.

The one or more endless conveyor belts (and the opposed portions of the conveyor belts) are on opposite sides of the path along which stacks of articles move in the machine direction through the apparatus in use. The path of the stacks of articles extends between the sets of one or more endless conveyor belts on either side of the path (and the opposed portions of the endless conveyor belts). The path of the stacks of articles herein refers to the general direction of travel of the stacks of articles through the apparatus. It will be appreciated that, in embodiments, the stacks of articles are supported on conveyor(s) of one of the sets of one or more conveyors on one side of the path of the stacks of articles as the stacks of articles travel along their path through the infeed, compression and outfeed regions e.g. the one or more conveyors of the lower one of the sets of one or more conveyors. The conveyor belts of the sets of endless conveyor belts are arranged so as to be on opposed sides of the stacks of articles as the stacks of articles travel along the path of the stacks through the infeed, compression and outfeed regions. Thus the apparatus may be said to comprise one or more endless conveyor belt arranged to be on one side of stacks of articles as they travel along their path through the infeed region, compression region and outfeed region in use, and one or more endless conveyor belt arranged to be on an opposite side of stacks of articles as they travel along their path through the infeed region, compression region and outfeed region in use.

In these further aspects, each conveyor belt of the one or more conveyor belts on each side of the path of the stacks of articles may form part of a respective conveyor assembly, which may be in accordance with any of the embodiments earlier described in relation to those aspects of the invention having first and second endless conveyor belts which provide the infeed, compression and outfeed regions. The apparatus may comprise any suitable driving arrangement for driving the belts. A common driving arrangement may be provided, or driving arrangements may be provided in respect of each belt.

The opposed portions of the paths of the endless conveyor belts defining the outfeed region may diverge from one another along the machine direction in the outfeed region so as to define an outfeed angle corresponding to an angle of divergence of the paths of the endless conveyor belts in the outfeed region. The outfeed angle may be in the range of from about 5 degrees to about 45 degrees, or optionally in the range of from about 5 degrees to about 15 degrees.

The opposed portions of the paths of the endless conveyor belts defining the infeed region preferably converge with one another along the machine direction in the infeed region. The paths may define an infeed angle corresponding to the angle of convergence of the paths of the endless conveyor belts in the infeed region, wherein the infeed angle is in -41 -the range of from about 5 degrees to about 45 degrees, or optionally in the range of from about 5 degrees to about 20 degrees.

The opposed portions of the paths of the endless conveyor belts defining the compression region preferably extend substantially parallel with one another along the machine direction. However, in other embodiments the opposed portions of the paths of the conveyor belts defining the compression region may converge with one another along the machine direction. Where the opposed portions of the paths of the endless conveyor belts defining the infeed region converge, the paths of the endless conveyor belts defining the infeed region may then converge with one another along the machine direction with a first angle of convergence in the infeed region, and the paths of the conveyor belts defining the compression region may converge with one another with a second angle of convergence in the compression region, wherein the first angle of convergence is greater than the second angle of convergence. The ratio of the first angle of convergence to the second angle of convergence may be at least 2:1 or at least 3:1.

The endless conveyor belts defining the compression region are spaced from one another by a given distance in the compression region to provide a compression gap. The spacing of the belts may be constant throughout the compression region. The compression gap size may be in the range of from about 2mm to about 75 mm, or from about 5mm to about 50mm. Where the compression gap varies within the compression region, as described above, the compression gap size corresponds to the closest spacing of the belts in the compression region.

The convergence or divergence angles, or the compression gap size are defined as described in relation to the earlier aspects and embodiments of the invention.

Each one of the conveyor belts may have any of the properties described earlier in relation to the first and second endless conveyor belts e.g. teeth, rigidity, surface properties etc. Preferably the apparatus comprises first and second endless conveyor belts, and the infeed, compression and outfeed regions are each provided between respective opposed portions of the paths of the first and second endless conveyor belts. Preferably the apparatus comprises a first endless conveyor belt on one side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region, and a second endless conveyor belt on an opposite side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region, wherein the infeed region, compression region and outfeed region are each defined between respective opposed portions of the paths of the first and second endless conveyor belts, wherein the respective opposed portions of the paths of the first and second endless conveyor belts defining the outfeed region diverge from one another along the machine direction. The apparatus is thus preferably in accordance with any of the earlier aspects and embodiments of the invention, and may include any of the features described in relation thereto. The use of the same pair of conveyor belts to provide each of the infeed, compression and outfeed regions eliminates the need to transfer stacks between conveyor belts as they pass between the regions, and is thus advantageous in providing the ability to more precisely control compression of the stacks of articles and better support stacks as they move between the different regions reducing the risk of stack stability or surface damage problems.

The first and second endless conveyor belts travel along respective first and second endless conveyor belt paths in the form of continuous loops. The first and second endless conveyor belts travel around respective sets of pulleys. Each set of pulleys includes at least one drive pulley and at least one driven pulley as previously described.

The apparatus may then be in accordance with any of the earlier described aspects and embodiments.

For example, the opposed portions of the paths of the first and second endless conveyor belts diverge from one another along the machine direction in the outfeed region so as to define an outfeed angle corresponding to an angle of divergence of the paths of the first and second endless conveyor belts in the outfeed region, optionally wherein the outfeed angle is in the range of from about 5 degrees to about 45 degrees, or optionally in the range of from about 5 degrees to about 15 degrees.

The opposed portions of the paths of the first and second endless conveyor belts may converge with one another along the machine direction in the infeed region. The opposed portions of the paths of the first and second endless conveyor belts may converge with one another in the infeed region so as to define an infeed angle corresponding to the angle of convergence of the paths in the infeed region, optionally wherein the infeed angle is in the range of from about 5 degrees to about 45 degrees, or optionally in the range of from about 5 degrees to about 20 degrees.

The opposed portions of the paths of the first and second endless conveyor belts defining the compression region preferably extend substantially parallel with one another along the machine direction. Alternatively the opposed portions of the paths of the first and second endless conveyor belts defining the compression region may converge with one another along the machine direction. Where the opposed portions of the paths of the first and second endless conveyor belts converge with one another in the infeed region along the machine direction, the paths of the first and second endless conveyor belts may then converge with one another along the machine direction with a first angle of convergence in the infeed region, and the paths of the first and second endless conveyor belts may converge with one another with a second angle of convergence in the compression region, wherein the first angle of convergence is greater than the second angle of convergence.

The ratio of the first angle of convergence to the second angle of convergence may be at least 2:1 or at least 3:1.

The first and second endless conveyor belt may be spaced from one another in the compression region to provide a compression gap, optionally wherein the spacing of the belts is constant throughout the compression region. The compression gap may have a size in the range of from about 2mm to about 75 mm, or from about 5mm to about 50mm.

In accordance with the invention in any of its aspects or embodiments, the stacks of articles are stacks of compressible articles. The stacks of articles are preferably unpackaged stacks of unpackaged compressible articles.

In preferred embodiments the articles are absorbent articles, such as, but not limited to, sanitary napkins, pants, tissue paper products or other hygiene products. The articles may be disposable absorbent articles. The articles may be dry articles (rather than pre-moistened articles such as wipes). However, the invention is applicable to other types of compressible article, such as stacks of insulation, e.g. loft insulation. The invention may be applied to stacks of a sheet material product, which may or may not be folded.

In particularly preferred embodiments the stacks of articles are stacks of tissue paper products, although in other embodiments the stacks of articles are stacks of articles other than tissue paper products.

A tissue paper product as referred to herein may be any type of tissue paper product, including, although not limited to, a bathroom tissue, facial tissue, or hand tissue.

The term "tissue" refers generally to various paper products, including facial tissue, bath tissue, hand tissue, paper towels, napkins and the like.

The tissue paper product may be any form of product obtained by converting a tissue paper basesheet into a product. The tissue paper product may comprise cellulosic fibers, although need not consist entirely of cellulosic fibers. For example, the tissue paper product may include synthetic fibers.

The basis weight of the tissue products may, for example, be less than about 80 grams per square meter (gsm), in some embodiments less than about 60 gsm, and in some embodiments, between about 10 to about 60 gsm A tissue paper product may comprise an organoleptic treatment. Such a treatment may impart the product with properties to influence a perception of the product, including one or more of a smell, taste, feel or colour of the product. Such a treatment may be applied e.g. through printing, spraying or may be incorporated in a slurry used to obtain the tissue paper material that formed the product. Thus the treatment may be a coating, or may be dispersed throughout the product. An example of an organoleptic treatment is a lotion..

A tissue paper product may be single ply or multi-ply. The product may comprise printing and/or embossment on a surface thereof In preferred embodiments the tissue paper product is a facial tissue, and the stacks of tissue paper products are stacks of facial tissues.

Regardless of the configuration of the articles, where the articles are tissue paper products the invention has been found to be particularly effective in compressing multi-ply tissue paper products, with two or even three plies or greater. The apparatus has been also found to result in improved compression even where the tissue paper products comprise an organoleptic treatment e.g. a surface coating.

The individual articles in a stack of tissue paper products may or may not be interfolded with one another. As used herein, the phrase "interfolded" tissue paper products e.g. tissues means that the tissue paper products are folded and interleaved with neighboring tissue paper products immediately above and/or below in the stack of tissue paper products. Consecutive tissue paper products may be attached to each other at perforation lines. In such cases, the unperforated segments of the perforation lines should be sufficiently weak to permit the consecutive tissue paper products to separate from each other upon removal from a package e.g. carton in which they are to be inserted. This can be controlled by the degree of perforation of the tissue paper sheet. Tissue paper products that may be employed in a non-interfolded stack of tissue paper products, which are not interleaved with neighboring tissue paper products are releasably attached to neighboring tissue paper products so that upon dispensing one tissue, the next adjacent tissue paper product is ready for dispensing.

Whatever the type of articles in the stack, any one or ones of the following may apply.

The stacks may be stacks of individual i.e. discrete articles, or the articles may be joined to one another along a frangible line of weakness e.g. perforations.

The stacks of articles may be stacks of folded articles, such as folded tissue paper products.

The stacks of articles may be identical stacks of articles i.e. of the same shape and including the same number of articles.

The articles within the stacks are preferably identical articles.

The stacks of articles may be of any suitable shape. In embodiments the footprint of each stack is square or rectangular. The stacks may therefore be in the shape of a cube or cuboid. The edges of the articles are aligned one above the other in the (intended) alignment of the stack.

In accordance with any of the method aspects of the invention, the method may comprise supplying stacks of articles to be compressed to the infeed region of the apparatus, and operating the compression apparatus such that the stacks of articles are conveyed along a path in the machine direction sequentially through the infeed region, compression region and outfeed region for compressing the stacks of articles.

The stacks of articles are supplied to the infeed region in a pre-compressed state. The stacks of articles are continually supplied to the infeed region of the apparatus i.e. as a continuous feed. The stacks of articles may be supplied as a stream of stacks of articles. The stacks of articles may be supplied to the infeed region from an upstream part of a system of which the apparatus forms part. In those aspects and embodiments in which the infeed, compression and outfeed regions are defined between opposed portions of the paths of first and second endless conveyor belts, the step of supplying the stacks to the infeed region may comprise supplying the stacks to the upstream end of the second endless conveyor belt.

The apparatus may form part of a system comprising an infeed conveyor assembly comprising an infeed endless conveyor belt for supplying stacks of articles to be compressed to the infeed region of the apparatus, and the method may then comprise supplying stacks of articles to the infeed region of the apparatus using the infeed conveyor belt. As described earlier, preferably a nose pulley is provided at a downstream-most end of the infeed conveyor assembly about which the infeed endless conveyor belt turns at the downstream-most end of its path to facilitate transfer of stacks of articles from the infeed endless conveyor belt to the endless conveyor belt at the upstream end of the apparatus e.g. to an upstream end of the second endless conveyor belt in embodiments having first and second endless conveyor belts which define the infeed, compression and outfeed regions.

The stacks may be supplied to the infeed region such that the consecutive stacks are spaced from one another along the path through which the stacks are conveyed along the machine direction through the infeed, compression and outfeed regions. The stacks may be supplied to the infeed region with a constant spacing between consecutive stacks of articles. For example, in embodiments the stacks may be supplied to the infeed region so as to be located on the second endless conveyor belt with a predetermined spacing along the machine direction. The spacing of the articles may be set based upon e.g. the speed of travel of an upstream conveyor e.g. an infeed conveyor and/or a speed of travel of the second endless conveyor belt.

In preferred embodiments the compression region has a length greater than or equal to, and preferably greater than, a length of each stack of articles to be compressed along the machine direction. This enables a stack of articles to fit fully within the compression region at at least one point in time as it travels therethrough.

The method may be performed such that only one stack of articles, or more than one stack of articles is at least partially within the compression region at any given time.

In accordance with the invention in any of its aspects or embodiments, the stacks of articles contact opposed i.e. facing surfaces of both of the opposed belts between which the respective region is defined (e.g. the first and second endless conveyor belts) throughout the compression region, along at least an upstream portion of the outfeed region, and optionally along at least a downstream portion of the infeed region. The stacks of articles are sandwiched between the opposed belts in these regions. The stacks of articles may, in embodiments in which the infeed, compression and outfeed regions are defined between first and second endless conveyor belts, be supported on the second endless conveyor belt such that they contact the second endless conveyor belt at all times during travel through the infeed, compression and outfeed regions. The stacks of articles may be supplied to an upstream end of the second endless conveyor belt upstream of an upstream end of the infeed region (which is defined by opposed portions of the first and second endless conveyor belts). The stacks of articles may continue to travel on the second endless conveyor belt downstream of a downstream end of the outfeed region (which is defined by opposed portions of the first and second endless conveyor belts) to a downstream end of the second endless conveyor belt.

The method may comprise operating the apparatus such that compressed stacks of articles cease to contact the facing surfaces of both of the opposed belts in the outfeed region (e.g. the first and second endless conveyor belts) at a point upstream of a downstream end of the outfeed region. The point may be upstream of a downstream-most pulley of the outfeed region about which one of the endless conveyor belts forming part of the outfeed region turns to commence a return portion of its path at the end of the outfeed region. Where the apparatus comprises first and second endless conveyor belts which define the infeed, compression and outfeed regions, the point may be upstream of a downstream-most pulley of the outfeed region about which the first endless conveyor turns to commence a return portion of its path. Such a pulley may correspond to a downstream-most pulley of the first conveyor assembly, e.g. the second outfeed region pulley in the embodiments described above. This may ensure that stacks of articles cease to contact the e.g. first endless conveyor belt before the belt starts to travel around the pulley, reducing the risk of damage to articles in the stack. Setting the point at which contact ceases may involve controlling various parameters, including the outfeed angle. The point will depend upon the extent to which stacks of articles recover in height after exiting the compression region, and will thus be influenced by factors affecting the recovery of the stacks of articles.

Alternatively or additionally, where a converging infeed is provided, the method may comprise operating the apparatus such that stacks of articles start to contact the facing surfaces of both of the opposed belts in the infeed region (e.g. the first and second endless conveyor belts) at a point downstream of a upstream end of the infeed region. The point may be downstream of an upstream-most pulley of the infeed region about which one of the endless conveyor belts forming part of the infeed region turns at the start of the infeed region to commence the portion of its path through the infeed region. Where the apparatus comprises first and second endless conveyor belts which define the infeed, compression and outfeed regions, the point may be downstream of an upstream-most pulley of the infeed region about which the first endless conveyor turns at the start of the infeed region to commence the portion of its path through the infeed region. Such a pulley may correspond to an upstream-most pulley of the first conveyor assembly, e.g. the first infeed region pulley in the embodiments described above. Setting the point of initial contact may involve controlling parameters including the infeed angle e.g. with respect to pre-compressed stack height.

The step of operating the compression apparatus may comprise operating the apparatus to drive the opposed conveyor belts thereof e.g. the first and second endless conveyor belts. The opposed belts on each side of the path along which stacks of articles travel e.g. first and second endless conveyor belts may be driven in opposite directions such that the belts all (or both) travel in the machine direction through the infeed, compression and outfeed regions.

The method may comprise driving the (sets of) opposed belts on either side of the path of the stacks of articles e.g. the first and second endless conveyor belts at the same speed or with a speed differential. As described above, whether or not a speed differential is appropriate will depend upon the types of articles to be compressed and other operating parameters. In some embodiments a speed differential may be helpful in order to reduce the risk of rhombussing of the resulting compressed stacks or of surface damage to articles in the stacks. The need for a speed differential or otherwise may be determined based upon consideration of the properties of compressed stacks of articles obtained i.e. in a feedback type arrangement. In embodiments in which driving arrangements for the first and second conveyor assemblies comprise respective servomotors, the method may comprise each servomotor controlling a speed of its motor based upon a target speed to achieve a target speed for the belt associated with the servomotor. This may be achieved in any of the manners described above e.g. based on a received target belt speed. The method may comprise a controller of the apparatus transmitting a respective target belt speed to each servomotor for use by the servomotor in controlling a speed of the motor thereof.

Regardless of whether a speed differential is used or not, or of the way in which belt speeds are controlled, the method may comprise driving each of the first and second endless conveyor belts at a speed of greater than 20m/min or greater than 30 m/min, or greater than 40m/min and optionally greater than 50m/min.

The method may comprise maintaining the outfeed angle constant as each stack of articles travels through the outfeed region. Alternatively or additionally the method may comprise maintaining the infeed angle constant as each stack of articles travels through the infeed region in embodiments having a converging belt infeed. Alternatively or additionally the method may comprise maintaining the opposed portions of the paths of the first and second endless conveyor belts parallel or converging at a constant angle of convergence in the compression region as each stack of articles travels therethrough. The method may comprise maintaining a spacing of the belts in the compression region unchanged as the stacks of articles pass through the compression region.

The stacks of articles supplied to the infeed region of the apparatus may be referred to as "pre-compressed" stacks of articles. The stacks of articles are pre-compressed in that they have not yet been compressed by the compression apparatus of the various aspects and embodiments of the present invention. It is envisaged that the articles in the stacks may have undergone some compression upstream of the infeed region e.g. during folding thereof. The stack as a whole is preferably uncompressed upon arrival at the infeed region, although it is not excluded that some degree of compression may have occurred as a result of upstream processes. The apparatus of the invention then provides additional e.g. final compression of the stacks of articles.

The stacks of articles supplied to the infeed region of the apparatus have a pre-compressed stack height. The pre-compressed stack height refers to the height of the stacks upon arrival at the infeed region of the compression apparatus before any compression is performed using the compression apparatus herein described.

After exiting the outfeed region of the compression apparatus, the stacks of articles are referred to as "compressed" stacks of articles. The compressed stacks of articles have a compressed stack height. The compressed stack height is measured immediately after exiting the outfeed region. It is envisaged that some "spring" back of the stack may occur once the stack is no longer confined within the compression region, as the stacks pass through the outfeed region or beyond. However, the apparatus described herein has been found to be useful in reducing the extent of such spring back. Any anticipated spring back may be accounted for when determining a suitable compressed stack height. For example, the compressed stack height may be selected to be suitably less than an applicable dimension of a package or an opening therein into or through which the compressed stack must fit.

No compressive force is exerted on the stack when measuring pre compression or compressed stack height as referred to herein.

The apparatus may form part of a system comprising an outfeed endless conveyor assembly comprising an outfeed endless conveyor belt for receiving compressed stacks of articles from the outfeed region of the apparatus. Preferably a nose pulley is provided at an upstream-most end of the outfeed conveyor assembly about which the outfeed endless conveyor belt turns at the upstream-most end of its path to facilitate transfer of stacks of articles to the outfeed endless conveyor belt from the second endless conveyor belt, optionally wherein a ratio of the diameter of the nose pulley to the diameter of a downstream-most pulley of the second conveyor assembly is from about 0.01 to about 0.3, or optionally from about 0.05 to about 0.2.

The outfeed conveyor belt may receive compressed stacks of articles from a conveyor belt at the downstream end of the apparatus. In embodiments in which the infeed, compression and outfeed regions are provided between first and second endless conveyor belts, the outfeed endless conveyor belt may receive compressed stacks of articles from a downstream end of the second endless conveyor belt.

The method may comprise packaging the compressed stacks of articles downstream of the outfeed region. Thus, packaging of the stacks only occurs after the stacks have exited the outfeed region. The stacks are packaged for the first time at this point. No packaging of the stacks of articles occurs upstream of the apparatus for compressing stacks of articles described herein, or within any of the infeed, compression or outfeed regions thereof. In embodiments no packaging occurs within the apparatus for compressing stacks of articles.

The packaging step is preferably carried out automatically, although it is envisaged that manual packing may alternatively be performed.

The method may comprise conveying the compressed stacks of articles after exiting the outfeed region to a packaging unit for automatically packing the compressed stacks of articles. In embodiments the apparatus forms part of a system comprising a packaging unit, and the method may comprise packaging the compressed stacks of articles in the packaging unit. The step of conveying the compressed stacks of articles may use any intermediate arrangement. In embodiments the apparatus forms part of a system comprising an outfeed conveyor, and the step may comprise conveying the articles along the outfeed conveyor. The outfeed conveyor may directly convey articles to e.g. a packaging unit, or some intermediate arrangement may be used.

In embodiments, regardless of how it is achieved, the step of packaging the compressed stacks of articles comprises packaging each stack of articles in a container, e.g. a rigid container, such as a box. The container may be a paperboard or cardboard container, for example. In some embodiments the container is a non-plastic container.

Each container may be used to hold only one compressed stack of articles.

The step of packaging a stack of article in a container may comprise inserting the stacks of articles into the container through an opening in the container and then closing the container. Thus, the container may be an already erected container. Where a packaging unit is provided, the packaging unit may be arranged to insert a compressed stack of articles into the container through an opening in the container and to then close the opening. The opening may be an open end of the container.

In some embodiments the method may comprise compressing the stacks of articles to a compressed height which is from about 70% to about 100%, or optionally from about 80% to about 95% of a height of an opening in a container through which the compressed stack of articles is to be inserted when packaging the compressed stack of articles and/or of a height of the container. The height of the opening in the container or the height of the container refers to the dimension of the opening of the container or of the container along the direction that the height of the compressed stack of articles extends as it is inserted into the container. This does not confer any limitation upon the intended orientation of the container in use. The opening may be an open end of the container. The height of the opening may then correspond to a height of the container.

The height of a stack of articles refers to the dimension of the stack in the direction in which compression occurs.

The method in any of its aspects or embodiments may comprise setting the outfeed angle to be in the range of from about 5 degrees to about 45 degrees, or optionally in the range of from about 5 degrees to about 15 degrees.

Alternatively or additionally the method may comprise setting the infeed angle to be in the range of from about 5 degrees to about 45 degrees, or optionally in the range of from about 5 degrees to about 20 degrees.

Alternatively or additionally the method may comprise setting the compression gap size to be in the range of from about 2mm to about 75 mm, or from about 5mm to about 50mm.

The method may comprise monitoring the properties of the resulting compressed stacks of articles and adjusting one or more operating parameters of the apparatus based on the determined properties. For example, one or more operating parameters may be adjusted if the resulting compressed stacks of articles show signs of surface damage and/or stack instability e.g. rhombusing. The one or more parameters that are varied may include any one or ones of; compression gap size, infeed angle, outfeed angle, belt speed, whether a belt speed differential is provided. The parameters may be adjusted when the conveyor belts are not running i.e. between runs of the apparatus.

Initial values of the parameters may be set empirically e.g. by performing trial compression of stacks of articles of the type and dimensions to be compressed in an actual run of the apparatus, and taking account of the resulting stack properties.

The method may comprise setting any one of the parameters of the apparatus described to have a range within any of the exemplified ranges e.g. to have an infeed angle, outfeed angle and/or compression gap size, within any of the ranges herein described.

The method may extend to any desired upstream processes to obtain the stacks of articles to be compressed. Such steps may include a step of stacking articles and/or a step of obtaining the articles to be stacked and/or a step of folding the articles. The apparatus may form part of a system comprising components for performing such steps. The system may comprise an article stacking sub-system upstream of the compressing apparatus, and optionally may include an article folding sub-system upstream of the article stacking sub- -51 -system. However, it will be appreciated that folding and/or stacking processes may be performed off-line.

The method may comprise the step of stacking a plurality of articles to obtain each stack of articles. Where the articles are folded articles, the method may comprise the steps of folding the articles and stacking the folded articles to provide the stacks of folded articles for supply to the infeed region of the apparatus. This may be performed in any desired manner. For example, articles may be added to stacks as they are folded, or a predetermined number of articles may be folded and then stacked etc. In embodiments the stacks of articles which are compressed using the apparatus have a thickness which varies along a first dimension of the stack and a maximum thickness that is constant along a second dimension of the stack. A maximum thickness is defined along the first dimension of the stack. The maximum thickness along the first dimension of the stack is the same at each point along the second dimension of the stack. Thus the same maximum thickness of the stack along a first dimension of the stack is defined when considering the thickness of the stack along the first dimension at any point along the second dimension of the stack. It has been recognised that it is advantageous for the stacks of articles to be introduced into the compression region with a predetermined orientation such that the maximum thickness of each stack is constant along the machine direction. This may avoid the pulleys of the compression region encountering variations in the maximum thickness of the stacks as they pass through the compression region in the machine direction e.g. resulting in "jumps" in the thickness of the stack presented for compression as it moves along the machine direction. It has been found that this may further help reduce the likelihood of castellation effects in the resulting compressed stacks of articles, or problems with stack stability.

Preferably the method comprises introducing each stack of articles to the compression region in a predetermined orientation with the second dimension of the stack, along which the maximum thickness of the stack is constant, oriented along the machine direction. The first dimension is then oriented along the cross direction. As the maximum thickness of the stack is constant along the second dimension of the stack, the maximum thickness of the stack which is presented for compression in the compression region is constant at all points as the stack moves along the machine direction.

It is believed that such embodiments are advantageous in their own right.

From a further aspect there is provided a method of compressing unpackaged stacks of folded articles; the method comprising; providing stacks of articles, wherein the stacks of articles have a thickness which varies along a first dimension of the stack and a maximum thickness that is constant along a second dimension of the stack, and supplying the stack of folded articles to a compression region for compressing the stack of folded articles in a predetermined orientation with the second dimension of the stack oriented along the machine direction.

The invention described herein in accordance with this further aspect may include any of the features described in relation to any other one of the other aspects of the invention described herein. Thus, the compression region may form part of a compressing apparatus or system as described in any of the embodiments or aspects herein.

The orientation of the stacks of articles as described may help to reduce stack stability issues resulting from the compression of the unpackaged stacks of articles. The articles may be unpackaged as in the earlier aspects and embodiments of the invention.

The articles may be of any of the types described herein, but are preferably stacks of folded tissue paper products, such as C-folded tissue paper products.

The compression region may be of any suitable form. In embodiments the compression region is provided between opposed conveyor belts. The belts may be parallel belts.

In these further aspects and embodiments in which thickness varies along a first dimension of the stack while a maximum thickness is constant along a second dimension thereof, in some embodiments the thickness of each stack of articles varies at different points across the first dimension of the stack so as to provide the stack with a thickness profile across a first dimension thereof, wherein at any given point along the second dimension of the stack, the stack exhibits the same thickness profile across the first dimension thereof The thickness profile along the first dimension is therefore uniform along the second dimension of the stack. A maximum thickness is defined within the thickness profile. As the thickness profile is constant along the second dimension of the stack, the maximum thickness of the stack will be constant along the second dimension, and will correspond to a maximum thickness defined within the thickness profile. The thickness profile includes at least a point of maximum thickness, and may include multiple points of the same maximum thickness, and/or one or more region of the maximum thickness. A thickness profile as used herein refers to a variation in thickness with respect to distance along a given dimension e.g. the first dimension.

The first and second dimensions of the stack are perpendicular. The first and second dimensions are each perpendicular to a thickness dimension of the stack. The first and second dimensions may correspond to a width and length of the stack. The length and width of the stack are used as labels and do not necessarily require that the stack is elongate. However, in embodiments the stack is elongate. The length (or second dimension) of the stack may, in embodiments, then correspond to the longer dimension thereof. Thus, the thickness of the stack may, in these embodiments vary across a first dimension of the stack e.g. a width thereof The thickness profile and the thickness of the stack is considered in its pre-compressed state if not explicitly stated herein. No compressive force is applied when measuring thickness.

The thickness of a stack of articles may vary in the manner described for a number of reasons. Variation in the thickness across the first dimension of the stack may result from one or more of; a folding configuration of the articles in the stack where the articles are folded articles, a variation in the thickness of the material of the articles in different regions of the articles, or a method of interfolding of the articles in the stack.

Where the articles are folded articles e.g. folded tissue paper products, a variation in thickness of the stack across a first dimension thereof, e.g. a thickness profile may result from differing numbers of layers of the material of the articles being present within the stack at different points across the first dimension of the stack. The differing numbers of layers may arise from a folding configuration of the articles and/or from a method of interfolding of the articles. The material of the articles within the stack may be of uniform thickness, such that each layer of an article is of the same thickness.

A thickness profile may arise in a stack where the articles in the stack themselves have such a thickness profile. In embodiments the articles in the stacks of articles which are compressed using the apparatus have a thickness which varies at different points across a first dimension of the article (e.g. so as to provide the article with a thickness profile across the first dimension thereof), and wherein a maximum thickness of the article is constant along a second dimension of the article (e.g. a thickness profile across the first dimension of the article is the same at any given point along the second dimension of the article). The articles are oriented in the stack such that the first dimension of each article is aligned with the first dimension of the stack and the second dimension of each article is aligned with the second dimension of the stack. Thus, the variation in thickness e.g. thickness profile of the article along the first dimension will give rise to a corresponding variation in thickness e.g. thickness profile in the stack. The thickness profile along the first dimension of the article is therefore uniform along the second dimension of the article. The first and second dimensions are perpendicular (and each perpendicular to a thickness dimension of the article). The first and second dimensions may correspond to a width and length of the article. The length and width of the articles are used as labels and do not necessarily require that the article is elongate. However, in embodiments the articles are elongate. The length (or second dimension) of the article may then correspond to the longer dimension thereof. Thus, the thickness of the article in these embodiments may, in some cases, vary across a first dimension of the article e.g. a width thereof.

In embodiments the articles are folded articles, such as folded tissue paper products. Folded articles may give rise to a stack of articles having the variation in thickness along a first dimension described. In some embodiments the articles are "C-folded" articles e.g. C-folded tissue paper products. Such articles may inherently have a variation in thickness of the type above described across a first dimension thereof, and may thus impart such variation in thickness to the stack. However, other or more complex fold patterns, such as a "J-folded" configuration may be used, and may give rise to such thickness variation in the articles and stack.

For example, a stack of C-folded tissue paper products e.g. facial tissues may be considered to have a first dimension across which thickness varies according to a thickness profile, corresponding to the dimension perpendicular to the dimension along which the folded edges extend. If the stack were to enter the compression region with a first dimension of the stack corresponding to the direction of the first dimension of the articles therein along the machine direction, while the thickness of the stack would be uniform across the cross machine direction at any given point along the first dimension of the stack, the maximum thickness presented for compression would vary along the machine direction. A thicker portion of the stack would be presented first, and then a thinner portion, and then a thicker portion again. If the stacks of articles are instead aligned such that a second dimension of the stack (corresponding to the direction of the second dimension of the articles along which the folded edges extend), along which a thickness profile is uniform is in the machine direction, a constant maximum height is presented for compression along the machine direction.

In these further aspects and embodiments of the invention, the stacks of articles may be stacks of folded articles e.g. tissue paper products, wherein each article comprises folded edges, the folded edges being aligned along a second dimension of the stack. The folding configuration of the articles may impart the stack with a first dimension along which the thickness of the stack varies and a second dimension along which the maximum thickness of the stack is constant. The method may comprise introducing each stack of articles to the compression region oriented with the folded edges of the articles i.e. the second dimension of the stack along the machine direction.

In embodiments, each folded article in the stack may comprise a longitudinally extending base panel and first and second longitudinally extending side panels connected to the base panel along respective foldlines extending along the longitudinal side edges of the folded article e.g. tissue, the first and second side panels being superposed on base panel, wherein the inner edges of the first and second side panels are spaced from one another along a first dimension of the article to impart the folded article with a varying thickness profile at different points across a first dimension of the article, wherein the first and second side panels and the base panel extend along the entire length of a second dimension of the folded article, such that the thickness profile is the same at any given point along the second dimension of the folded article. In such arrangements the longitudinal side portions of the folded tissue in which the first and second side panels are superposed on the base panel comprise a greater number of layers of tissue than a central portion of the folded article e.g. tissue where only the base panel is present. The central portion is a transversely central region extending along the second dimension of the article. The central portion may define a central longitudinally extending strip. The folded article may be symmetrical about a longitudinal centerline thereof It is envisaged that the folded article may include only the base panel and first and second panels (e.g. providing a C-folded article e.g. tissue) or may include one or more further panels e.g. sandwiched between respective ones of the first and second side panels and the base panel and/or superposed on the respective side panels, provided that a thickness profile is provided across the first dimension of the article, which is uniform along the second dimension of the article. The first and second dimensions may correspond to a width and length of the folded article. Terms such as longitudinal and transverse are used as labels and do not necessarily require that the folded article is elongate. However, in embodiments the folded articles are elongate.

Each folded article is oriented in the stack with its first and second dimensions aligned along respective first and second dimensions of the stack. When such a stack of folded articles is oriented with a second dimension thereof along the machine direction for entry into the compression region, the foldlines connecting the first and second panels to the base panels of the articles therein will be aligned along the machine direction.

Preferably the stacks of articles enter the infeed region of the apparatus with the above described preferred predetermined orientation (with a second dimension of the stack along the machine direction), and remain in such an orientation throughout the infeed, compression and outfeed regions.

Depending upon the upstream processes used, it may be necessary to reorientate the stacks of articles in order to ensure that they enter the compression region with the desired predetermined orientation. The reorientation may be a rotation of the stacks e.g. through 90 degrees.

For example, in some embodiments stacks of articles may be produced or otherwise received upstream with the first dimension, along which the thickness varies, in the machine direction, and the second dimension, along which the maximum thickness does not vary, in the cross machine direction. The method may then comprise reorientating e.g. rotating the stacks before they enter the compression region to result in the stacks of articles being in the predetermined orientation, with the second dimension of the stacks oriented along the machine direction. The reorientation e.g. rotation may be from an initial orientation in which the stacks of articles have their first dimension along the machine direction. The initial orientation may be an orientation of the stacks of articles after stacking of the articles to provide the stacks. The method may extend to the step of stacking articles to provide the stacks of articles having the initial orientation. Where the stacks of articles are folded articles, the method may further comprise folding the articles and then stacking the folded articles. A stack reorientation e.g. rotation sub-system may be provided upstream of the compression region (or infeed region/compressing apparatus) for reorientating stacks as described.

Where reorientation of the stacks of articles is required, preferably the reorientation takes place upstream of the infeed region of the apparatus.

The apparatus in accordance with any of its aspects or embodiments may form part of a system comprising a stack reorientation e.g. rotation sub-assembly located upstream of the infeed region. The system may optionally further comprise an article stacking subsystem upstream of the stack reorientation sub-assembly. An article folding sub-system may be located upstream of the article folding sub-system.

It will also be appreciated by those skilled in the art that all of the described embodiments and aspects of the invention described herein can, and in an embodiment do, include, as appropriate, any one or more or all of the features described herein.

Preferred embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments will now be described, by way of example only, and with reference to the accompanying drawings in which: Fig. 1 shows a perspective view of a system including a compression apparatus comprising upper and lower conveyor assemblies comprising respective upper and lower conveyor belts for receiving and compressing stacks of articles therebetween, and the system also including an infeed conveyor assembly and an outfeed conveyor assembly; Fig. 2A shows a side view of the compression apparatus, illustrating some features in greater detail; Fig. 2B is a schematic representation of the relative position of the pulleys and conveyor belts of the compression apparatus; Fig. 3 shows a longitudinal cross-section of a conveyor belt suitable for use as the upper conveyor belt and the lower conveyor belt of the apparatus for compressing a stack of articles.

Fig. 4A illustrates the path of upper and lower conveyor belts in an arrangement where no tapered outfeed region is provided; Fig. 4B illustrates the path of the upper and lower conveyor belts after a compression region when a tapered outfeed region is provided; Fig. 5A is a detail view showing an upstream end of the compression apparatus, and how it may interact with an upstream infeed conveyor assembly; Fig. 5B shows an outfeed conveyor assembly, and how it may interact with a downstream outfeed conveyor assembly; Fig. 6 illustrates schematically a driving arrangement for the compression apparatus; Fig. 7 illustrates compression of a series of stacks of articles by the compression apparatus; Fig. 8 is a flowchart of a method of compressing stacks of articles which are stacks of tissues; Fig. 9 is a schematic illustration of various stages of a system that includes the compression apparatus, through which a stack of articles may be sequentially conveyed according to a method of compressing stacks of articles; Fig. 9A shows a top view of a tissue prior to folding; Figs. 9B and C respectively show a top and side view of a tissue after folding into a C-fold; Figs. 9D and E respectively show a top and side view of a stack of C-folded tissues which may be compressed using the present compression apparatus; Fig. 9F shows an orientation of stacks of C-folded tissues to be compressed using the present compression apparatus as they enter the compression apparatus; Figs. 10A and 10B show exemplary packaging for a compressed stack of tissues; Fig. 11A shows a side view of a stack of articles; Figs. 11B to 11D show various defects that could occur when compressing a stack of tissues, wherein Fig. 11A shows a rhombussed stack of articles, Fig. 11C shows tearing of tissues in a stack of tissues, and Fig. 11D shows castellations in a compressed stack of tissues.

DETAILED DESCRIPTION

As discussed above, the present invention relates to an apparatus for compressing a stack of articles, and to associated methods. The apparatus is configured to mechanically compress a stack of articles which is not packaged (e.g. such that the articles are loose, also referred to herein as a "naked" stack of articles). The articles within the stack may also not be packaged (may be unpackaged). When performing mechanical compression of such naked stacks of articles, it can be difficult to maintain stability of the stack (wherein a lack of stack stability can result in stack deformation), and it can also be difficult to prevent damage to articles in the stack. The present apparatus and methods include various features which alone or in combination may help to reduce the occurrence of such stack defects during mechanical compression.

Fig. 1 shows an embodiment of an apparatus 700 for compressing a stack of articles (also referred to herein as the "compression apparatus" 700), in accordance with the present invention. The compression apparatus 700 may form part of a system that includes a suitable infeed conveyor assembly 500 and outfeed assembly 600.

The compression apparatus 700 comprises an infeed region 1, a compression region 2 and an outfeed region 3, each defined between opposed portions of the paths of a first conveyor belt 101 and a second conveyor belt 201. The infeed region 1, compression region 2 and an outfeed region 3 are arranged sequentially after one another along a machine direction (MD) of the apparatus 700. In use stack of articles 900 are conveyed in the machine direction through the infeed region 1, then through the compression region 2, and then through the outfeed region 3, as shown for example in Fig. 7.

The machine direction (MD) and also the cross machine direction (CD) are shown in Fig. 1. The machine direction (MD) and the cross machine direction (CD) have the usual meaning in the art.

The infeed region 1 is provided between opposed portions of the paths of the first conveyor belt 101 and the second conveyor belt 201 which converge with one another. In other words, the first and second conveyor belts 101, 201 converge in the infeed region 1. Thus the infeed region 1 is tapered in the machine direction so as to gradually compress stacks of articles in use as it is transported in the machine direction through the infeed region 1 towards the compression region 2. The compression region 2 comprises an extended region along the machine direction provided between parallel opposed portions of the paths of the first and second conveyor belts 101, 201, and is arranged to maintain stacks of articles in a compressed state in use as the stacks travel in the machine direction through the compression region 2. The outfeed region is provided between diverging opposed portions of the paths of the and second conveyor belts 101, 201, and is thus tapered in the machine direction so as to gradually release the pressure from stacks of articles in use as the stacks are transported in the machine direction from the compression region 2 through the outfeed region 3.

The apparatus 700 comprises a first conveyor assembly 100 and a second conveyor assembly 200 for conveying stacks of articles in the machine direction.

The first conveyor assembly 100 comprises the first conveyor belt 101, which is an endless conveyor belt. The first conveyor belt 101 is supported by a plurality of pulleys 102a-102h such that the first conveyor belt is directed along a path which is a closed loop.

The closed loop path of the first conveyor belt 101 has an outward portion comprising the infeed region 1, compression region 2 and outfeed region 3, and a return portion connecting a downstream end of the outfeed region 3 to an upstream end of the infeed region 1. The pulleys 102a-102h each extend along and are configured to rotate about an axis aligned in the cross-machine direction. An inner surface 103 of the first conveyor belt faces the inside of the closed loop, and an outer surface 104 of the first conveyor belt faces outwards of the closed loop. The inner (pulley facing) surface 103 contacts the pulleys 102a-102h. The outer (stack facing) surface 104 and contacts stacks of articles in use.

Similarly, the second conveyor assembly 200 comprises the second conveyor belt 201, which is an endless conveyor belt. The second conveyor belt 201 is supported by a plurality of pulleys 202a-202h, such that the second conveyor belt 201 is directed along a path which is a closed loop. The closed loop path of the second conveyor belt 201 has an outward portion comprising the infeed region 1, compression region 2 and outfeed region 3, and a return portion connecting a downstream end of the outfeed region 3 to an upstream end of the infeed region 1.

The pulleys 202a-202h each extend along and are configured to rotate about an axis aligned in the cross-machine direction. An inner surface 203 of the second conveyor belt faces the inside of the closed loop, and an outer surface 204 of the second conveyor belt faces outwards of the closed loop. The inner (pulley facing) surface 203 contacts the pulleys 202a-202h. The outer (stack facing) surface 204 contacts stacks of articles in use.

In the infeed region 1, the compression region 2 and the outfeed region 3, paths of each of the first and second conveyor belts 101, 201 are arranged in opposition to one another, such that the outer surface 104 of the first conveyor belt faces the outer surface 204 of the second conveyor belt.

Hence, the apparatus 700 is arranged such that, in use, stacks of articles can be received between opposing portions of the paths of the first and second conveyor belts 101, 201 in the infeed region 1, compression region 2, and outfeed region 3. Hence, the opposing portions of the conveyor belts 101, 201 can contact opposite sides of each stack of articles in the compression region 2, and in at least part of the infeed region 1 and outfeed region 3. The contact of the opposing portions of the conveyor belts 101, 201 with opposite sides of a stack of articles allows a compressive force to be applied to those opposite sides of the stack of articles as the stack of articles is conveyed through the apparatus 700.

The apparatus 700 is configured to drive the each of the first and second conveyor belts 101, 201 such that each of the first and second conveyor belts 101, 201 are driven in the machine direction through the infeed region 1, the compression region 2 and the outfeed region 3. In this manner, the first and second conveyor belts 101, 201 are operable to contact opposite sides of the stack of articles and apply a compressive force to the opposite sides of the stack of articles whilst simultaneously conveying the stack of articles in the machine direction. Hence, the first and second conveyor belts 101, 201 counter-rotate with respect to one another.

In the embodiment shown in Fig. 1 the first conveyor belt 101 is driven by a drive pulley 102g which is the downstream-most pulley of the first conveyor assembly 100. The drive pulley 102g is operably connected to a drive 105, wherein the drive 105 comprises a servomotor. Similarly, the second conveyor belt 201 is driven by a drive pulley 202g which is the downstream-most pulley of the second conveyor assembly 200. The drive pulley 202g is operably connected to a drive 205, wherein the drive 205 comprises a servomotor. The other pulleys 102a-102f, 102h, 202a-202f and 202h are guide pulleys. At least some, and preferably all, of the guide pulleys engage a respective one the conveyor belts and are driven to rotate as a result of the movement of the respective conveyor belt as the conveyor belt is driven. The guide pulleys may, therefore, be referred to herein as "driven pulleys".

The driving arrangement will be discussed in more detail below.

In the embodiment shown in Fig. 1, the first conveyor assembly 100 is an upper conveyer assembly and the second conveyor assembly 200 is a lower conveyer assembly. Hence, when operational, the first conveyor assembly 100 is positioned above the second conveyor assembly 200 in the z-direction. The z-direction corresponds to a vertical direction.

Accordingly, the first conveyor belt 101 is an upper conveyor belt, and the second conveyor belt 201 is a lower conveyor belt.

In such an arrangement, in use, a stack of articles may be positioned on top of the second (lower) conveyor belt 201, such that the stack of articles is supported on the second conveyor belt 201 as the stack of articles is conveyed through the infeed region 1, the compression region 2 and the outfeed region 3 of the compression apparatus 700.

The path of the second conveyor belt 201 extends substantially horizontally in the embodiment of Fig. 1 in the infeed region 1, the compression region 2 and the outfeed region 3 to form a substantially flat, horizontal, path in the machine direction for supporting stacks of articles. In contrast, the vertical level of the path of the first conveyor belt 101 varies relative to the path of the second conveyor belt 201 in the machine direction of the compression assembly 700, to provide the tapered infeed region 1, the compression region 2, and the tapered outfeed region 3.

Various features of the compression apparatus 700 can similarly be seen from Fig. 2A and Fig. 2B, wherein like features are shown using like numerals. In Figs. 2A and 2B, the infeed region 1, compression region 2, and outfeed region 3 are each shown hatched. In particular, Fig. 2A is a side view of the apparatus. In Fig. 2A, exemplary mountings of the pulleys 102a-h and 202a-h to respective frames 117 and 217 can be seen. However it will be appreciated that the frames 117 and 217 at least partially obscure the pulleys themselves. The relative position of the pulleys 102a-h and 202a-h and their respective axes can be better seen from the schematic representation in Fig. 2B. Fig. 2B is essentially a simplified cross-sectional view of compression apparatus 700, showing only the relative positions of the pulleys 102a-h and 202a-h and conveyor belts 101, 201. Some features in Fig. 2B have been exaggerated for the sake of illustration. As will be discussed in the following, one or more, or preferably all, of the pulleys have a toothed outer surface.

However, for the sake of readability, Fig. 2B represents each pulley as a circle having a diameter equal to the outermost diameter of the pulley.

-61 -Tapered infeed region As discussed above, the compression apparatus 700 is provided with a tapered infeed region 1. The opposed portions of the paths of the conveyor belts 101, 201 of the first and second conveyor belt assemblies 100, 200 converge in the infeed region 1.

The paths of the conveyor belts 101, 201 define an infeed angle a in the infeed region. The infeed angle a may also be referred to herein as the "convergence angle" or "angle of convergence".

The path of the first conveyor belt 101 in the infeed region 1 is substantially planar, and extends along a plane 106. Hence, the path of the first conveyor belt 101 in the infeed region 1 defines the plane 106. In particular, the outer (stack contacting) surface 104 of the first conveyor belt defines the plane 106.The plane 106 is angled at the infeed angle a relative to a plane 206 defined by the path of the second conveyor belt 201 in the infeed region 1. In particular, the outer (stack facing) surface 204 of the second conveyor belt 201 defines the plane 206. As noted above, the path of the second conveyor belt 201 is substantially horizontal in the infeed region, and so the plane 206 extends substantially horizontally. This is shown in Figs. 2A and 2B. Whilst the first and second conveyor belts 101, 201 do not actually touch in the infeed region 1, the infeed angle a may still be determined from the relative angle between the direction of the planes 106, 206 and their notional point of intersection shown in dotted lines.

The planes 106, 206 exclude any surface undulations that may be present, and any smooth transitions that may occur between the infeed region 1 and the compression region 2.

In the embodiment shown in Fig. 1, the infeed region 1 starts at an upstream-most pulley 102a, and extends to a pulley 102d, wherein pulleys 102a and 102d support the first conveyor belt 101. Pulley 102d is positioned downstream of the pulley 102a in the machine direction, and vertically closer to the second conveyor assembly 200 relative to pulley 102a.

As shown in Figs. 2A and 2B, A length L1 of the infeed region may be measured as the distance between the axis of the upstream-most pulley 102a and the axis of the pulley 102d in the machine direction.

The pulley 102a may be referred to as a "proximal" pulley, since it is the upstream-most pulley in the machine direction of the first conveyor assembly 100.

The path of the first conveyor belt 101 extends linearly between the pulleys 102a and 102d in a substantially planar fashion, thereby defining the plane 106. Hence, the angle a of the plane 106 of the first conveyor belt 101 relative to the plane 206 of the second conveyor belt 201 is determined by the relative position of pulleys 102a and 102d.

Whilst one or more other pulleys 102b, 102c may be present between pulleys 102a and 102d in order to support the first conveyor belt 101 in the infeed region 1, as shown in Fig. 2, the other pulleys do not substantially change the direction of the path of the first conveyor belt between the pulleys 102a and 102d. In this manner, the inclined path of the first conveyor belt between the pulleys 102a and 102d remains substantially planar, which can assist with providing an even and gradual increase in pressure to stacks of articles as the stacks of articles are conveyed in the machine direction in use.

The first conveyor assembly 100 is configured such that the infeed angle a can be varied. In particular, the angle a can be varied by mechanical adjustment of the position of the upstream-most pulley 102a.

As shown in Figs. 1 and 2A, the upstream-most pulley 102a is mounted at the distal end of an arm 107, the arm 107 being rotatable about a pivot point 108. As shown in Fig. 2A, the pivot point may correspond to the axis of the pulley 102d which defines the most downstream end of the infeed region 1. The pulley 102d also defines the start of the compression region, as will be discussed below.

The one or more other pulleys 102b, 102c between the pulleys 102a and 102d may also be mounted to the arm 107 so that the pulleys 102b, 102c are moveable with the arm 107. In this manner, the upper conveyor belt assembly is configured such that when the infeed angle a is adjusted (by moving the proximal pulley 102a by pivoting the arm 107) the path of the first conveyor belt 101 in the infeed region 1 remains substantially planar.

The upper conveyor belt assembly 100 may be configured to allow for manual adjustment of the infeed angle a. Alternatively, the infeed angle a may be adjusted by a computerised or otherwise automated adjustment.

For example, as shown in Fig. 2, the arm 107 may be held at a given position to maintain an infeed angle a by means of a supporting arm 118. The supporting arm is extendible such that the length of the supporting arm 118 may be varied to allow movement of the arm 107. The supporting arm 118 is, in the illustrated embodiment, extendible using a screw thread arrangement, although other arrangements are possible e.g. a hydraulic arm. The arm 107 comprises a slot 115 moveable about a captive screw 109 when the captive screw is loosened. The slot 115 and captive screw 109 may act to limit the amount by which the arm 107 can be moved. The captive screw 109 may also assist in locking the arm in position when it is tightened. The arm 107 may have a scale 110 associated with it, wherein the scale is configured to provide information indicative of the infeed angle a (although other angle indicating means could be used).

The infeed angle a may be adjustable between positive angles greater than zero. For example, the infeed angle a may be adjustable up to 45°, preferably from about 5° to about 15°. Such angles may be particularly suitable for compressing stacks of tissues.

The length of the arm 107, in combination with the infeed angle a will determine the length L1 of the infeed region. For example, the arm 107 may have a length measured from the axis of pulley 102d to the axis of pulley 102a along the direction of the arm of from about 0.7m to 1.3m, preferably from about 0.9 m to 1.1 m.

Alternatively, arrangements other than an arm 107 could be used for adjusting infeed angle a. For example, the pulley 102a could instead be mounted to any other movable element, e.g. such as a slidable plate similar to that discussed below with respect to the outfeed region.

The length L1 of infeed region 1 and the infeed angle a may affect how gradually stacks of articles compressed in use. For instance, a relatively longer infeed region 1 and relative smaller infeed angle a may generally allow a more gradual compression of a stack of articles in the infeed region 1 prior to the compression region 2, and in use may assist in reducing distortion of stacks of articles (e.g. such as rhombussing of stacks of articles, as illustrated and described with respect to Fig. 11 B). However, a longer infeed region 1 to provide gradual compression in the infeed region 1 may need to be balanced against the cost of any additional length of the first conveyor belt 101. Furthermore, the stability of the infeed region 1 may be negatively affected if the arm 107 is so long as to become unstable in use, which could in turn introduce defects in a stack of articles conveyed through the infeed region 1 in use. In practise, a suitable infeed angle a may be determined empirically based on trial and error, or may be determined using a suitable calculation or computer model.

The adjustable infeed angle a also allows various heights of stacks of articles to be received by the apparatus 700 for compression, up to a maximum height of stack. The maximum height of stack that can be received may be defined by the maximum infeed angle a to which the apparatus can be adjusted. In use, the infeed angle a could be adjusted to select a particular (e.g. predetermined) point at which a stack of articles will contact the upper conveyor belt 101. In this manner, the length in the machine direction over which compression occurs due to contact with the first conveyor belt 101 can be selected.

Compression region As discussed above the apparatus 700 is provided with a compression region 2, downstream of the infeed region 1 in the machine direction. The compression region 2 is configured to receive stacks of articles from the infeed region 1, and to convey those stacks of articles in the machine direction to the outfeed region 3. Whilst being conveyed through the compression region 2, the stacks of articles are maintained in a compressed state.

As shown in Figs. 1 and 2, in the compression region 2, paths of the first and second conveyor belts 101, 201 oppose one another and are substantially parallel to one another. Hence, in the compression region 2, the paths of both the first and second conveyor belts 101, 201 extend substantially horizontally.

The compression region 2 is elongated in the machine direction such that it comprises an extended region in which the first and second conveyor belts 101, 201, face one another and are spaced apart from each other by a compression gap 114. In other words, the compression region 2 is not merely a nip point.

Various parameters such as the size of the compression gap 114, the length L2 of the compression region, and the speed at which articles are conveyed through the compression region 2 (i.e. the speed of the upper and lower conveyor belts in the compression region 2) may be selected as appropriate for different types of stacks of articles. For example, the length L2 of the compression region 2 can be balanced with the speed of travel of the stacks of articles through the compression region, to cause stacks of articles to spend a predefined period of time within the compression region 2. This may, in combination with the size of the compression gap 114, influence the amount of height regained by the stack (i.e. the amount by which the stack "springs back") after exiting the apparatus 700. The size of compression gap 114 may be adjustable between runs, then the first and second conveyor belts 101, 201 are not running. For example, the size of compression gap 114 may be adjustable whilst no stacks of articles are being conveyed through the compression region 2.

As shown in Figs. 1, 2A and 2B, the compression region 2 comprises a first set of pulleys 102f, 102e and 102d which are pulleys of the first conveyor assembly 100. Similarly, the compression region 2 comprises a second set of pulleys 202f, 202e and 202d which are pulleys of the second conveyor assembly 200.

As shown in Figs. 1, 2A and 2B, the first and second sets of pulleys are arranged as pairs of opposed pulleys, wherein the axes of the pulleys in each pair are at a same location in the machine direction. In other words, the axes of the pulleys in each pair of opposed pulleys are aligned in the machine direction.

In particular, the compression region extends between a first pair of opposed pulleys 102d, 202d and a second pair of opposed pulleys 102f, 202f which are spaced apart from the first pair of opposed pulleys in the machine direction. The first pair of opposed pulleys 102d, 202d and the second pair of opposed pulleys 102f, 202f respectively define the start and end of the compression region in the machine direction. The length L2 of the compression region may be defined as the distance in the machine direction between the axes of the first pair of opposed pulleys 102d, 202d and the axes of the second pair of opposed pulleys 102f, 202f.

Hence, in the compression region 2, the first conveyor belt 101 extends between pulleys 102d and 102f of the upper conveyor assembly 100. The pulleys 102d and 102f are spaced apart from one another in the machine direction and are arranged to tangentially contact the first conveyor belt 101 at the same height. Similarly, in the compression region 2, the second conveyor belt 201 extends between pulleys 202d and 202f of the lower conveyor assembly 200. The pulleys 202d and 202f are spaced apart from one another in the machine direction and are arranged to tangentially contact the second conveyor belt 201 at the same height. In this manner, the paths of each of the first and second conveyor belts 101, 201 extend substantially horizontally within a plane, and substantially parallel to one another, in the compression region between the first set of opposed pulleys 102d, 202d and the second set of opposed pulleys 102f, 202f. The relative height of the pulleys is shown in particular in Fig. 2B.

Other intermediate pulleys 102e, 202e may be arranged between the first pair of opposed pulleys 102d, 202d and a second pair of opposed pulleys 102f, 202f to support the first and second conveyor belts 101, 201 along their planar paths. The intermediate pulleys 102e, 202e may be arranged as pairs of opposed pulleys.

The planes of the paths of the first and second conveyor belts 101, 201 in the infeed region 2 are defined by the outer (stack facing) surfaces 104, 204 of the first and second conveyor belts 101, 201. The planes are defined to ignore surface undulations, and other slight variations, e.g. due to a smooth transition between the infeed region 1 and the compression region 2 or a smooth transition between the compression region 2 and the outfeed region 3.

As shown in Figs. 2A and 2B, the first pulley 102d of the compression region 1 which contacts the upper conveyor belt 101, corresponds to the same pulley which defines an end of the infeed region 1. Hence, the compression region 2 follows immediately after (and transitions directly into) the infeed region 1 in the machine direction. Between the infeed region 1 and the compression region 2 the path of the first conveyor belt 101 may transition smoothly from a plane angled at the infeed angle a to a plane which is substantially horizontal, as the first conveyor belt 101 contacts and passes around at least part of the pulley 102d.

The last pulley 102f of the compression region 1 which contacts the upper conveyor belt 101, corresponds to the same pulley which defines a start of the outfeed region 3. Hence, the outfeed region 3 follows immediately after (and transitions directly into) the compression region 2 in the machine direction. Between the compression region 2 and the outfeed region 3 the path of the first conveyor belt 101 may transition smoothly from a plane extending substantially horizontally to a plane which extends at the outfeed angle p, as the first conveyor belt 101 contacts and passes around at least part of the last pulley 102f.

The pulleys within each pair of opposed pulleys may have the same diameter as one another, which may assist with applying an even pressure to both sides of a stack of articles in use. The pulleys of the first pair of opposed pulleys 102d, 202d and the second pair of opposed pulleys 102f, 202f have a larger diameter than the pulleys of the one or more intermediate sets of pulleys 102e, 202e.

Hence, the first pulley 102d and the last pulley 102f of the pulleys which support the first conveyor belt 101 in the compression region may have a diameter which is larger than the diameter of one or more intermediate pulleys 102e positioned between the first pulley 102d and the last pulley 102f. The relatively larger diameter of the pulleys 102d and 102e may allow for a gradual change in angle of the path of the first conveyor belt 101 as it transitions from the infeed region 1 (in which the path extends at the infeed angle a) to the compression region 2 (in which the path extends substantially horizontally), and similarly as it transitions from the compression region 2 to the outfeed region (in which the path extends at the outfeed angle (3). This gradual change in direction of the path of the first conveyor belt 101 may avoid damage to a stack of articles as it is conveyed into and out of the compression region in use, and may also reduce wear on the first conveyor belt 101 since it requires less flexion.

For example, the pulleys of the first pair of opposed pulleys 102d, 202d and last pair of opposed pulleys 102f, 202f may have an outermost diameter of at least about 100mm, preferably at least about 130 mm. The outermost diameter of the first pair of opposed pulleys 102d, 202d and last pair of opposed pulleys 102f, 202f may be less than about 200mm, preferably less than about 150mm.

The pulleys of the one or more pairs of intermediate pulleys 102e, 202e may have an outermost diameter of less than about 100mm, preferably less than about 85mm. The pulleys of the one or more pairs of intermediate pulleys 102e, 202e may have an outermost diameter of greater than about 50mm, preferably greater than about 75 mm.

As discussed above, in the compression region, the pulleys are arranged as respective opposed pairs of pulleys. This paired arrangement may allow a consistent pressure to be applied to both sides of a stack of articles passing though the compression region 2 in use. In use, the compressive force applied to a stack of articles between the upper and lower conveyor belts 101, 201 may relax somewhat between the pairs of opposed pulleys. In the embodiment shown in Figs. 2A and 2B, the apparatus comprises three pairs of opposing pulleys in the compression region. In use, however, fewer or more pairs of opposing pulleys could be used. For example, the apparatus could comprise 2, 3, 4, 5, or more pairs of opposing pulleys in the compression region. The number of pairs of opposing pulleys could be selected depending, for example, on one or more of: the type of stacks of articles that are to be compressed by the apparatus, a length L2 of the compression region, and the amount of compressive force intended to be provided in the compression region.

Alternatively the first set of pulleys that contact the first conveyor belt 101 may be offset in the machine direction relative to the second set of pulleys that contact the second conveyor belt 201. For example, one or more of the pulleys may not directly oppose another pulley.

In another alternative, the first set of pulleys that contact the first conveyor belt 101 in the compression region 2 may comprise a different number of pulleys than the second set of pulleys that contact the second conveyor belt 201 in the compression region. In this case, the length of the compression region L2 may be defined as the distance in the machine direction between the axes of the first pulley 102d and the last pulley 102f of the first set of pulleys which contact the first conveyor belt 101 in the compression region 2.

Other supporting structures, such as support plates could be positioned to support the first and second conveyor belts in the compression region 2. However, in the arrangement shown in Figs. 1, 2A and 2B the first and second conveyor belts 101, 201 are supported only by pulleys in the compression region 2. Such an arrangement can still provide a sufficiently large and sufficiently even compressive force, whilst avoiding excessive friction and wear on the conveyor belts.

In the arrangement shown in Figs. 1 and 2, the pulleys in the compression region 2 are guide pulleys, and are not drive pulleys.

As noted above, the compression region 2 is elongate and has a length L2 which results in stacks of articles being maintained in a compressed condition for an extended period of time as they are conveyed through the compression region.

In embodiments, the length L2 of the compression region is from about 100mm to 300mm, preferably from about 175mm to 275mm, preferably from about 200 to 250mm.

In embodiments, the length L2 of the compression region 2 is greater than the length in the machine direction of stacks of articles which are to be compressed by the apparatus. Hence, the apparatus is configured such that the compression region 2 has a length L2 sufficient to contain a stack of articles to be compressed in its entirety within the compression region 2. This can assist with maintaining the stability of the stack of articles as it is conveyed in the machine direction through the compression apparatus 700.

As noted above, in the compression region 2, there is a gap 114 between the paths of the first and second conveyor belts 101, 201. The gap 114 is also referred to herein as the "compression gap". The size of the gap 114 is measured in the z-direction between the outer surface 104 of the first conveyor belt 101 and the outer surface 204 of the second conveyor belt 201 in the compression region 2 when the apparatus 700 is not running. Due to the path of the first and second conveyor belts 101, 201 being substantially parallel in the compression region 2, the size of the gap 114 is substantially the same within the compression region 2. In particular, the size of gap 114 is substantially the same across both the machine and the cross machine directions in the compression region 2.

The apparatus is configured such that the compression gap 114 is adjustable. This allows the size of the compression gap to be adjusted and therefore optimised depending on the stack of articles to be compressed. For example, when a stack of tissues is to be compressed, the compression gap may be adjusted depending on at least one of: the original height of the stack of tissues prior to compression by the apparatus, the number of tissues in the stack, the number of plies in each tissue, the basis weight of each tissue (in grams per square meter, gsm). Along with various other parameters associated with the compression apparatus, the compression gap height may influence the quality of compression of the stacks.

In an embodiment, the first conveyor assembly 100 is moveable in the z-direction relative to the second conveyor assembly 200 in order to adjust the size of the compression gap 114. In particular, the entirety of the first conveyor belt 101 and the pulleys 102a-102h of the first assembly 100 are moveable in the z-direction. For example, the pulleys 102a- 102h of the upper conveyor belt assembly 100 may be mounted to a moveable portion of a frame of the apparatus. The first conveyor assembly 100 may be configured to move vertically relative to the second conveyor assembly 200, so that the compression gap can be adjusted, without changing the infeed angle a or outfeed angle R. In this regard, the first conveyor assembly 100 may be configured to move vertically in its entirety, without affecting the relative position of the pulleys 102a-102h within the first conveyor assembly 100.

Alternatively, any other suitable arrangement may be provided for adjusting the compression gap 114. For example, an alternative arrangement may allow only pulleys 102d-102f that support the first conveyor belt 101 within the compression region 2 to be moved closer to or further from the second conveyor belt 201 in the z-direction.

In embodiments, the apparatus 700 is configured such that, during adjustment of the compression gap 114, the path of the first conveyor belt 101 in the compression region 2 remains substantially parallel to the path of the second conveyor belt 201 in the compression region 2.

The apparatus may be configured such that the compression gap size is adjustable anywhere within the range of 2mm and 75mm, preferably within 5 mm and 50mm. These values may be particularly suitable for compressing stacks of tissues.

The apparatus 700 may be configured to allow manual adjustment of the compression gap 114 when the apparatus is not running. Alternatively, the apparatus 700 may be configured to allow automated or other electronic adjustment of the compression gap 114.

The apparatus 700 may be provided with a scale or other indication for indicating to a user the size (height) of the compression gap, e.g. such that upon adjustment of the compression gap a user is presented with information indicative of the new adjusted compression gap size. Although it is described above that the paths of the first and second conveyor belts 101, 201 are substantially parallel in the nip region 2, the paths could alternatively be at an angle relative to one in the nip region 2 such that the paths converge (or diverge) slightly in the nip region 2. For example, the paths of the first and second conveyor belts 101, 201 could converge in the compression region 2. at an angle less than the infeed angle a. Alternatively, the paths of the first and second conveyor belts 101, 201 could diverge in the compression region 2 at an angle less than the outfeed angle is. In this case, the size of the compression gap referred to above will correspond to the smallest gap between the first and second conveyor belts 101, 201 in the compression region.

Tapered outfeed region As discussed above, the apparatus 700 is provided with a tapered outfeed region 3 located after the compression region 2. In the outfeed region 3, the paths of first and second conveyor belts 101, 201 diverge from one another in the machine direction. In use, the divergence has the effect of gradually removing the compressive force from a stack of articles as the stack of articles is conveyed through the outfeed region 3 in the machine direction.

The paths of the conveyor belts 101, 201 define an outfeed angle p in the outfeed region. The outfeed angle [3 may also be referred to herein as the "divergence angle" or "angle of divergence".The path of the first conveyor belt 101 in the outfeed region 3 is substantially planar, and defines a plane 110. In particular, the outer (stack contacting) surface 104 of the first conveyor belt defines the plane 110. The plane 110 is angled at the outfeed angle p relative to the plane 206 defined by the path of the second conveyor belt 201 in the outfeed region 2. As noted above, the path of the second conveyor belt 201 is substantially horizontal in the outfeed region, and so the plane 206 extends substantially horizontally. This is shown in Figs. 2A and 2B.

Whilst the first and second conveyor belts 101, 201 do not actually touch one another in the outfeed region 2, the outfeed angle p may still be determined from the relative angle between the direction of the planes 110 and 206 and their notional point of intersection shown in dotted lines.

The planes 110, 206 exclude any surface undulations that may be present, and any smooth transitions that may occur between the compression region 2 and the outfeed region 2.

In the embodiment shown in Figs. 1, 2A and 2B, the outfeed region 3 starts at a pulley 102f, and extends to a downstream-most pulley 102g, of the first conveyor assembly 100, wherein pulleys 102f and 102g support the first conveyor belt 101. Pulley 102g is positioned downstream of the pulley 102f in the machine direction, and vertically further from the second conveyor assembly 200 relative to pulley 102f.

Pulley 102f corresponds to a pulley of the last, downstream-most, pair of opposed pulleys in the compression region 2. Pulley 102g corresponds to downstream-most pulley of the first conveyor assembly 100. Pulley 102g may also be referred to herein as a "distal" pulley since it is the last pulley in the machine direction of the first conveyor assembly 100.

The path of the first conveyor belt 101 extends linearly between the pulleys 102f and 102g in a substantially planar fashion, thereby defining the plane 110. Hence, the angle 3 of the plane 110 of the first conveyor belt 101 relative to the second conveyor belt 201 is determined by the relative position of pulleys 102f and 102g.

Unlike the infeed region, the outfeed region shown in Figs. 1 and 2 does not comprise any other pulleys to support the first conveyor belt 101 between pulleys 102f and 102g. In this regard, the outfeed region is generally shorter than the infeed region, and so it may not be necessary to provide such additional supporting pulleys. However, if desired one or more other pulleys could be present between pulleys 102f and 102g in order to support the first conveyor belt 101 in the outfeed region 2 to support the planar path of the first conveyor belt 101 in the outfeed region 2.

As shown in Fig. 2, the pulley 102d which defines the start of the outfeed region 3 is the same pulley 102d that defines the downstream end of the compression region 2, such that the outfeed region 3 follows immediately after the compression region 2 in the machine direction. Between the compression region 2 and the outfeed region 3 the path of the first conveyor belt 101 transitions smoothly from being oriented in a substantially horizontal direction (in the compression region 2) to being oriented at the outfeed angle p (in the outfeed region 3), as the first conveyor belt 101 contacts and passes around at least part of the pulley 102f.

In this regard, it has been found that including a tapered outfeed region 3 as part of the path for a stack of articles can help to reduce the occurrence (and severity) of stack defects compared to a path that ends abruptly at the end of the compression region 2. The difference between such arrangements is shown in Figs. 4A and 4B.

For the purposes of illustration, Fig. 4A shows a modified arrangement wherein the tapered outfeed region has been removed such that the path for a stack of articles between opposing upper and lower conveyor belts 101, 201 terminates abruptly at the end of a compression region 2. In this case, the upper conveyor belt 101 is directed through compression region 2 and then around a final pulley 102f of the compression region to travel essentially back on itself so as to form a closed loop of the upper conveyor belt (loop not shown in full). Hence, the final pulley 102f of the compression region acts as a "return" or "tail" pulley. The belt wrap around the final pulley 102f in this arrangement is significant, e.g. with the belt contacting the circumference of the pulley over an arc having an angle 0 of greater than 90 degrees, and potentially as large as 180 degrees. The angle 0 of the arc is measured from the axis of the pulley.

In the arrangement of Fig. 4A, due to the upper conveyor belt 101 having a thickness which is not negligible, as the belt 101 travels around the pulley 102f (corresponding to a significant amount of belt wrap, as mentioned above), the outer surface 104 of the belt accelerates and travels faster than the inner surface 103. As an analogy, this -71 -is similar to the situation in an athletic running track, wherein the outside runner has to run faster than the inside runner to maintain the same position on the track.

It was found that acceleration of the outer surface 104 about the pulley 102f in the arrangement of Fig. 4A can accordingly exert a force on the top of a stack of articles which can cause articles to become damaged. For example, in the case of a stack of tissues, the top tissues may be ripped or torn as the outer surface 104 of the conveyor belt 101 accelerates. Such damage is can be particularly problematic for stacks of tissues if the grip of the tissues to the belt 101 results in a force that is higher than the strength of the tissue. The damage was also found to be worse if the plies of the tissues are unable to slide relative to one another. The ability of plies to slide over one another may depend on the composition of the tissues, and any additives or lotions or the like that have been applied to the tissues. Such tearing is shown in Fig. 11C.

Furthermore, in embodiments, the upper and lower conveyor belts 101, 201 are driven such that they travel at the about same speed through the compression region 2 (or at a slight speed differential). This can help to improve stack stability in the compression region. However, in an arrangement such as Fig. 4A, the acceleration of the upper belt 101 as it travels around the pulley 102f would change the relative speeds of the upper and lower belts 101, 201 in the region of the pulley 102f, which could cause instability in a stack of articles as it exits the compression region 2, and could cause the stack to become deformed. One type of deformation that may occur is rhombussing, which is illustrated and described in more detail below with respect to Fig. 11 B. It will be appreciated that the arrangements disclosed in EP 2680732 would suffer from such drawbacks, particularly if used to compress stacks of unpackaged articles.

In comparison, an arrangement in accordance with the invention, such as shown in Fig. 4B, which has a tapered outfeed region 3, may assist with reducing the occurrence of rhombussing and damage to articles (e.g. tissues) in a stack of articles. In this case, the upper belt 101 does not travel as far around the final pulley 102f of the compression region, such that it transitions from being horizontal to travelling at the outfeed angle 13. The belt wrap around the final pulley 102f can be such that the first conveyor belt 101 contacts the pulley over an arc having an angle y which is less than 90 degress, and may be less than 60 degrees, preferably less than 45 degrees. As a result, the outer surface 104 of the first conveyor belt 101 does not accelerate to as high a speed as the arrangement of Fig. 4A, and so exerts less force on the upper portion of a stack as the stack exits the compression region 2. Hence, the arrangements of the present invention, as illustrated in Fig. 4B, may therefore less likely to damage, e.g. rip, articles at the top of a stack of articles.

Furthermore, in the arrangement of Fig. 4B, the path of the upper conveyor belt 101 continues in opposition to the path of the lower conveyor belt 201 throughout the tapered outfeed region, and therefore in use continues to contact a stack of articles for at least a portion of the outfeed region 2. This continuing contact with (and gradual release of pressure from) a stack of articles can improve stack stability and help to reduce the effect of rhombussing.

The first conveyor assembly 100 is configured such that the outfeed angle [3 can be varied when the assembly is not running. In particular, the angle of divergence p. can be varied by mechanical adjustment of the position of the distal pulley 102g. This allows the outfeed angle 13 to be adjusted between runs depending on the stack(s) of articles that are to be compressed. The angle [3 may be adjustable from about 0 degrees to 45 degrees, preferably from 5 degrees to 15 degrees. Preferably, the angle [3 is selected to be in a range from about 5 degrees to 15 degrees in use when compressing stacks of tissues.

In the embodiment shown in Figs. 1 and 2A, the upper conveyor assembly 100 is configured to allow manual adjustment of the position of the distal pulley 102g. The distal pulley 102g is mounted on a plate 111 which is moveable in the z-direction. The plate 111 is held in place by captive screws 112. The plate 111 is associated with a scale 113 which provides an indication of the position of the distal pulley 102g, and hence provides information indicative of the outfeed angle 13.

Alternatively, the distal pulley 102g could be moveable by any other suitable means.

For example the distal pulley 1 0 2 g could be mounted on a pivotal arm similar to that described with regards to the proximal pulley 102a of the infeed region.

Alternatively, the angle 13 of divergence may be adjustable by an electronic or otherwise automated adjustment.

The assembly may be configured such that at least one of (and preferably all of) the infeed angle a, the outfeed angle 13 and the size of the compression gap 114 can be independently adjusted.

The assembly may be configured such that at least one of (and preferably all of) the infeed angle a, the outfeed angle p and the size of the compression gap 114 cannot be adjusted whilst the compression apparatus 700 is running. Hence, the assembly may be configured such that at least one of (and preferably all of) the infeed angle a, the outfeed angle 13 and the size of the compression gap 114 cannot be adjusted whilst the conveyor belts 101, 201 are being driven. Hence, the assembly may be configured to maintain a fixed angle a of convergence of the infeed region, a fixed angle 13 of the outfeed region, and a fixed size of the compression gap 114 in use.

For example, the assembly may comprise suitable security features to prevent a user from adjusting at least one of (and preferably all of) the angle of convergence a, the angle of divergence 3 and the size of the compression gap 114 whilst the compression apparatus 700 is running. The security features may comprise, for example, a control system operable to set an indication (e.g. a warning light) to alert a user that the assembly is currently running and should not be adjusted. Alternatively, or additionally the control system may selectively enable or disable a physical barrier (e.g. guard or door) to prevent access to the assembly whilst the assembly is running.

The various pulleys discussed above which are part of the first and second conveyor belt assemblies 100, 200 may be held in position in any suitable manner, for example, by mounting on a respective frame, such as frames 117 and 217 shown in Figs. 1 and 2A. The first and second conveyor belt assemblies 100, 200 may be arranged to allow for tensioning of the first and second conveyor belts by moving one or more of the pulleys relative to other pulleys of the first and second conveyor belt assemblies 100, 200.

In the example shown in Fig. 2A, the first conveyor assembly 100 comprises a tensioning means which allows the upstream-most pulley 102a of the first conveyor assembly 100 to be moved. In particular, the pulley 102a may be moved by adjusting the length of the arm 107, by means of one or more captive screws 119 moveable within respective 120 slots of the arm 107. In the example shown in Fig. 2A, either or both of pulleys 202a and 202h may be moved to adjust the tensioning of the second conveyor belt 201. In particular, each of pulleys 202a and 202h are mounted on a respective plate 218, 221 which is held in position relative to the frame 217 by means of respective captive screws 219, 222 movable in respective slots 220, 223. However, in other arrangements, one or more of the other of the pulleys could be moveable to allow for tensioning. Preferably, however, the pulleys 102d, 102e, 102f and 202d, 202e, 202f which are compression region pulleys are not moveable for tensioning the belts 101, 201. Belts

When mechanically compressing a stack of articles, potential problems include distortion of the stack (e.g. such as rhombussing), damage to the articles, and modification (e.g. damage, or other changes) to a surface of the stack of articles which is being brought into contact with a compressing means (such that the first or second conveyor belt with a compression apparatus of the type disclosed herein). These problems may be exacerbated due to the relatively high torque and pressure that may be applied in order to mechanically compress a stack of articles.

In particular, for a naked stack of tissues, potential problems can include distortion of the stack (e.g. such as rhombussing), tearing of the tissues (especially the uppermost tissues which are adjacent the first conveyor belt in use), and distortion of the surface of the stack (e.g. such as castellations, described below).

In this regard, it is recognised in the present application that various properties of the first and second conveyor belts can affect the occurrence of stack related problems. Fig. 3 illustrates the a portion of a belt 300 suitable for use as the first conveyor belt 101 and/or the second conveyor belt 201 in the present compression apparatus 700. Fig. 3 also shows a portion of a pulley 400 of the compression apparatus 700, and shows schematically how the belt 300 may engage the pulley 400.

The belt 300 has a first side 303 having a first surface 313 corresponding to the inner surface 103 or 203 discussed with respect to Figs. 1, 2A and 2B. The first side 303engages one or more pulleys (102a-102h and 202a-202h) of the compression apparatus 700. The belt also comprises a second side 304 having a second surface 314 corresponding to the outer surface 104 or 204 discussed with respect to Figs. 1, 2A and 2B. The second side contacts stacks of articles in use.

The first side 303 is adapted to appropriately grip pulleys of the compression apparatus 700, such that sufficient torque can be applied to the belt 300 when acting as the first or second conveyor belt 101, 210 of the compression apparatus 700. The first side comprises a plurality of cross machine direction oriented elongate teeth 306 which are spaced at an interval t along the length of the belt, so as to impart the inner surface of the belt with a pattern of alternating peaks 307 and troughs 308 along the length of the belt.

Each tooth 306 extends across at least a portion of width of the belt 300 in the cross machine direction. Preferably, each tooth 306 extends across substantially the entire width of the belt 300 in the cross machine direction.

One or more (and preferably all) of the pulleys 102a-102h and 202a-202h of the assembly are toothed pulleys (such as the toothed pulley 400 of which a portion is shown in Fig. 3).

Each toothed pulley 400 comprises a plurality of axially oriented elongate teeth 406 spaced at intervals around the circumference of the pulley, wherein the teeth impart the outer belt contacting surface of the pulley with a pattern of alternating peaks 407 and troughs 408 around the circumference of the pulley. The peaks 407 and troughs 408 are defined in a radial direction of the pulley.

The teeth 406 may be spaced around the entire circumference of the pulley 400. The teeth 406 extend axially along at least part of the pulley, for example along at least a belt-contacting portion of the pulley or along substantially the entire axial length of the pulley.

The pulley 400 and belt 300 are configured such that teeth 306 of the belt 300 nest between teeth 406 of the pulley 400. The teeth 306 of the belt 300 may nest between the teeth 406 of the pulley 400 across the entire width of the belt 300 in the cross-machine direction.

The combination of toothed pulleys 400 for at least some of the pullleys 102a-102h and 202a-202h of the assembly with toothed belts 300 as the first second conveyor belts 101, 201 allows the toothed first and second conveyor belts to grip the pulleys for sufficient torque to be applied to the first and second conveyor belts. However, it has been found that toothed pulleys can, in some circumstances, cause undesirable impressions or distortions on the surface of a stack of articles when the stack of articles is conveyed through the apparatus is use. These distortions may comprise "castellations" which appear as corrugations in the surface of the stack of articles, as illustrated and described with respect to Fig. 11D.

It has been found that such castellations may be noticeably worse if the valleys 308 between the teeth 306 of the belt 300 are unsupported when the belt 300 engages the pulley 400. For example, such a situation can arise if the top of a tooth 307 of the belt 300 contacts the bottom of a valley 408 of the pulley 400, but the tooth 306 of the belt has a height that is large enough that the bottom of the valley 308 of the belt 300 does not contact a top of the tooth 406 of the pulley 400.

In contrast, the belt 300 and pulleys 400 of the present assembly are configured such that, when a belt 300 engages a pulley 400, a valley 308 of the belt 300 is contacts a top of a tooth 406 of the pulley. More specifically, at least the bottoms of the valleys 308 of the belt contact the tops of the teeth 406 of the pulleys 400. This can help to improve support of the belt on the pulley, and it may assist with reducing the occurrence of castellations.

As shown in Fig. 3, the valleys 308 of the belt 300 have bottom which has a substantially flat surface 309. The top of each tooth 406 of the pulley 400 also has a substantially flat surface 409which engages the substantially flat surface 309of the bottom of the valleys 308 of the belt 300. In this manner, the belt 300 is supported over a larger area compared to if, for example, a bottom of the valleys 308 were curved or pointed.

Although not shown in Fig. 3, provided that a bottom of the valley 308 of the belt 300 is supported by a top of a tooth 406 of the pulley 400, the top of a tooth 306 of a tooth 306 of the belt could also contact a bottom of a valley 408 of the pulley 400, if desired. In this case the top of each tooth 306 could comprise a substantially flat surface and the base of each valley 408 could comprise a substantially flat surface, if desired. However, increased support due to more contact points between the belt and pulleys should be balanced against a potential increase in friction and wear on the belts.

The teeth 306 of the belt may be spaced apart evenly, being separated by a distance (pitch) t from about 5 to about 50 mm, preferably from about 5 to about 10 mm.

The valleys 308 of the belt may similarly be spaced apart evenly, being separated by a distance (pitch) t from about 5 to about 50 mm, preferably from about 5 to about 10 mm. Each tooth 306 may have a height lit measured from the base of the valley 308 to the top of the tooth 306, of from about 1 mm to about 10 mm, preferably from about 2 mm to 5mm.

Such dimensions may be particularly suitable for belts used when compressing stacks of tissues.

Similarly, the teeth 406 of the pulley 400 may be spaced apart evenly about the circumference of the pulley 400, being separated by a distance (pitch) from about 5 to about mm, preferably from about 5 to about 10 mm. The valleys 408 of the pulley belt may similarly be spaced apart evenly, being separated by a distance (pitch) from about 5 to about 50 mm, preferably from about 5 to about 10 mm. Each tooth 406 may have a height hp measured from the base of the valley 408 to the top of the tooth 406. The ratio of the height hp to the height ht may be from about 1 to about 1.5.

The belt 300 should be relatively robust, such that the outer surface 314 of the second side 304, which contacts a stack of articles in use, does not substantially distort when the belt 300 contacts the teeth 406 of the pulleys 400. Having a relatively robust belt may aid in reducing the occurrence of castellations in stacks of articles (e.g. such as stacks of tissues) when they are compressed using the present compression apparatus 700. In this regard, the second side 304 may comprise a base layer 311, which has tailored properties such as strength, rigidity and hardness. In embodiments, the base layer 311 has a Shore A hardness of at least 40, preferably from about 50 to about 80. The Shore hardness can be measured using a durometer.

It has been found that the texture of the outer surface 314 of the belt 300 may have an effect on the occurrence of defects in a stack of articles to be compressed. For example, if the outer surface 314 of the belt 300 (which contacts the stack of articles in use) has a coarse texture, then articles in a stack of articles may at least partially adhere to the second surface 314, which may increase the chance of damage to the surface of the articles in the stack of articles. For example, for fibrous articles such as tissues, fibers may, in some circumstances, become embedded within a textured outer surface of a belt, causing articles to adhere to the outer surface of the belt and to tear. Tissue dust may also tend to accumulate within a textured surface during use of the compression apparatus, which may, over time, alter the properties of the textured surface and therefore potentially affect the consistency and reliability of the apparatus.

Hence, it may be desirable to select the properties of the belt to reduce the likelihood of surface damage to stacks of articles, e.g. such as tearing of tissues if the stack comprises a naked stack of tissues. To this end, in embodiments the outer surface 314 of the belt 300 (which contacts a stack of articles in use) is substantially smooth. Hence, the outer surface 314 of the belt 300 does not have any substantial surface embossments, protrusions or recesses. The outer surface 314 of the belt 300 may, however, have a fine grain structure. Alternatively, the outer surface 314 of the belt 300 may be polished or machined to remove any visible grain structure.

The outer surface 314of the belt 300 may be an antistatic surface. The outer surface 314 of the belt 300 may comprise one or more release agents, to inhibit articles of a stack of articles from sticking to the outer surface 314 of the belt 300 in use.

As noted above, the belt 300 has a first (inner) side 303 for engaging a pulley 400, and a second (outer) side 304 for contacting a stack of articles in use. The apparatus may be arranged such that no pulleys contact the second (outer) side 304. This can avoid damage to the second side 304, and also prevent any contaminants from stacks of articles being transferred to the pulleys of the apparatus in use.

Hence, with reference to Figs. 1, 2A and 2B, the apparatus 700 is arranged such that the inner surface 103 of the first conveyor belt 101 (corresponding to the inner surface 313 of the belt 300 shown in Fig. 3) contacts a plurality of pulleys 102a-102h to define the path of the first conveyor belt. The outer surface 104 of the first conveyor belt 101 (corresponding to the outer surface 314 of the belt 300 shown in Fig. 3), which contacts stack of articles in use. The outer surface 104 of the first conveyor belt 101 does not contact any of the pulleys of the apparatus 700. Similarly the inner surface 203 of the second conveyor belt 201 contacts a plurality of pulleys 202a-202h to define the path of the second conveyor belt. The outer surface 204 of the second conveyor belt 201 contacts a stack of articles in use. The outer surface 204 of the second conveyor belt 201 does not contact any of the pulleys of the apparatus 700.

The apparatus 700 is arranged such that the path of each of the first and second conveyor belts 101, 201 is not subject to any contraflexure. Hence, the path of each of the first and second conveyor belts 101, 201 does not include any points of inflection. Hence, the pulleys 102a-102h of the first conveyor assembly 100 are positioned such that the first conveyor belt 101 is supported on a path which is a closed loop, wherein the path has no points of inflection. The path of the first conveyor belt 101 thus defines a shape having interior angles which are all less than 180 degrees. Similarly, the pulleys 202a-202h of second first conveyor assembly 200 are positioned such that the second conveyor belt 201 is supported on a path which is a closed loop, wherein the path has no points of inflection. Thus the path of the second conveyor belt 201 defines a shape having interior angles which are all less than 180 degrees.

Such an arrangement which contains no points of inflection may assist with reducing wear of the first and second conveyor belts 101, 201, particularly if the first and second conveyor belts 101, 201 each comprise a belt 300 that is relatively rigid (which, as discussed above may be used to help to reduce the occurrence of castellations).

The present application further recognises that, when the first and second conveyor belts 101, 201 are relatively rigid, it may be possible to reduce the wear on the belts by ensuring that the belts do not bend excessively in use. Hence, the pulleys 102a, 102d, 102e, 102g and 105h which form corners of the shape defined by the path of the first conveyor belt 102 may be selected to have a relatively large diameter, to avoid excessive bending of the first conveyor belt 102 as it travels around those pulleys. In particular, the upstream-most pulley 102a and downstream-most pulley 102g of the first conveyor assembly, which have a significant bend angle in order to change the direction of the first conveyor assembly, may have a relatively large diameter. Similarly, the pulleys 202a, 202g and 205h which form corners of the shape defined by the path of the second conveyor belt 201 may have a relatively large diameter, to avoid excessive bending of the second conveyor belt 201 as it travels around those pulleys. In particular, the upstream-most pulley 202a and downstream-most pulley 202g of the first conveyor assembly, which have a significant bend angle in order to change the direction of the first conveyor assembly, may have a relatively large diameter.

To assist with maintaining the stability of a stack of articles, as can be seen from Figs. 1, 2A and 2B, the first conveyor assembly 100 comprises only a single conveyor belt 101 which has a path that extends through the infeed region 1, the compression region 2, and the outfeed region 3. Similarly, the second conveyor assembly 200 comprises only a single conveyor belt 201 which has a path that extends through the infeed region 1, the compression region 2, and the outfeed region 3. Hence, the apparatus 700 is configured such that, as a stack of articles is conveyed through the infeed region 1, the compression region 2, and the outfeed region 3, the opposite sides of the stack of articles are each contacted by only a single conveyor belt. As shown in Figs. 1 and 2, each of the first and second conveyor belts 101, 201 are a continuous material which extends substantially across the entire width of the conveyor in the cross-machine direction (i.e. across substantially the entire width of each belt-engaging pulley on which the first and second conveyor belts 101, 201 are supported).

The compression apparatus may comprise two (or more) lanes for compressing two (or more) streams of stacks of articles emanating from upstream processing in parallel. Each lane may comprise an upper conveyor belt 101 and a lower conveyor belts 201 arranged to from an infeed region 1, a compression region 2, and an outfeed region 3 in a similar manner to that described above. Each of the lanes may be adjacent to one another in the cross machine direction Driving arrangement The apparatus 700 comprises a driving arrangement for driving the first and second conveyor belts 101, 201. The first and second conveyor belts 101, 201 may each be driven by one or more drive pulleys. In the embodiment shown in Fig. 1, the first conveyor belt 101 is driven by a single drive pulley 102g, which is the most downstream of the pulleys of the outfeed region.

Similarly the second conveyor belt 201 is driven by a single drive pulley 202g, which is the most downstream of the pulleys of the outfeed region. Alternatively, a different pulley of the pulleys could be the drive pulley. Alternatively, each of the first and second conveyor belts 101, 201 could be driven by plural drive pulleys.

The drive pulleys 102g, 202g are each driven by a servomotor 105, 205. Each servomotor comprises sensing circuitry (e.g. one or more sensors) sensing one or more parameters of the servomotor indicative of a speed of the motor (e.g. parameters such as the position, speed and/or torque of the motor). Each servomotor may comprise a closed-loop servomotor which is configured to self-check its actual speed to ensure consistent speed. Furthermore, each servomotor may be have a higher torque capability than, for example, a standard AC induction motor, which may assist in preventing the servomotors from struggling under the loads required within the compression apparatus 700 to compress stacks of articles.

As illustrated in Fig. 6, each servomotor may be in communication with a controller 701 of the compression assembly 700. The controller may be configured to compare a speed of each servomotor with a target speed, and to send control signals to the servomotors to control the speed of each servomotor. The target speed for each servomotor may be adjusted depending on the particular stack(s) of articles which are to be compressed to achieve a target belt speed.

The controller 701 may be operable (and configured to) control each servomotor 105, 205, independently and to maintain the servomotors 105, 205 (and hence the first and second conveyor belts 101, 201) at the same speed or at a pre-determined (or set) speed differential. In this regard, it has been found that, for some stacks of articles, maintaining a difference in speed (a speed differential) between the first and second conveyor belts 101, 201 can help to reduce the effect of rhombussing and also reduce the chance of damage to articles in the stack of articles (e.g. such tearing of upper tissues of a stack of tissues). The required difference in speed differential may be small, and so the provision of servomotors 102, 205 is useful since they allow very precise control of the speed.

If it is desired to run the servomotors 105, 205 at exactly the same speed, the controller 701 may be configured to electronically gear together the servomotors 105, 205.

As mentioned above, the compression apparatus 700 may be part of a system comprising an infeed conveyor assembly 500 and an outfeed conveyor assembly 600. The controller 701 may be operable to control a speed at which a conveyor belt 501 of the infeed conveyor assembly 500 and a conveyor belt 601 of the outfeed conveyor assembly 600 are driven. The controller may be configured to adjust the relative speeds of the conveyor belts 101, 201, 501, 601.

Although the above is described with respect to servomotors, and other type of motor could be used. For example, other arrangements could use, a single drive (e.g. an AC motor in an open loop configuration) being adapted to drive both of the first and second conveyor belts 101, 201 at the same speed.

Infeed/outfeed conveyor assemblies In order to supply a stack of articles to the infeed region 1 of the apparatus 700, an infeed conveyor assembly 500 may be provided, as shown in Fig. 1. Similarly, in order to remove a compressed stack of articles from the outfeed region 3 of the apparatus 700, an outfeed conveyor assembly 600 may be provided.

As shown in Fig. 1, the infeed conveyor assembly comprises an infeed conveyor belt 501. The infeed conveyor belt 501 is arranged upstream of (and adjacent to) the second conveyor belt 201 of the second conveyor assembly 200 in the machine direction, such that a stack of articles conveyed on the infeed conveyor belt 501 may be transferred (directly) onto the second conveyor belt 201.

The infeed conveyor belt 501 is supported by one or more pulleys 502 (and optionally, one or more other support elements such as support plates). The infeed conveyor assembly 500 is configured such that an (upper) path of the infeed conveyor belt 501 (on which a stack of articles is to be supported in use) extends substantially horizontally in the machine direction. The infeed conveyor assembly 500 may comprise a suitable drive (e.g. motor) for driving the infeed conveyor belt 501 such the upper surface of the path of the infeed conveyor belt 501 moves in the machine direction.

The (upper) path of the infeed conveyor belt 501 may be substantially aligned with the path of the second conveyor belt 201 in the z-direction, such that a stack of articles riding on (supported by) the infeed conveyor belt 501 can be transferred to the second conveyor belt 201. Alternatively (and preferably) there is a drop between the path of the infeed conveyor belt 501 and the path of the second conveyor belt 201, such that a stack of articles can drop slightly onto the second conveyor belt 201 in use (this has been found to help prevent a stack from being deformed during transfer to the second conveyor belt 201).

The infeed conveyor belt 501 and the second conveyor belt 201 may be positioned close to one another, so as to provide a relatively small gap between the infeed conveyor belt 501 and the second conveyor belt 201. This may help to allow a stack of articles to be transferred from the infeed conveyor belt 501 to the second conveyor belt 201 without becoming unstable or deforming.

However, as noted above, the most upstream pulley 202a of the second conveyor assembly 200 may advantageously have a relatively large diameter which may help to avoid excessive bending of the second conveyor belt 201 about that pulley, especially where the belt 201 is relatively rigid. As a result, it can be difficult to bring the infeed conveyor belt 501 close to the second conveyor belt 201 in order to reduce the gap, which can help to reduce the chance of stack instability when a stack is transferred from the infeed conveyor belt 501 to the second conveyor belt 201. Therefore, some intermediate arrangement may be used to bridge the gap. For example, a single pulley 502 of a moderate size may be used to support the infeed conveyor belt at a downstream end of the infeed conveyor belt 501, in combination with a plate 505 (also referred to as a "dead plate") or other supporting element -81 -that bridges a gap between the pulley 502 of the infeed conveyor assembly 500 and the most upstream pulley 202a of the second conveyor assembly 200. In such an arrangement, in use, a stack of articles can ride on the plate 505 or other supporting element when being transferred between the infeed conveyor belt 501 and the second conveyor belt 201). The moderately sized pulley 502 may have a diameter which is, for example, from about 0.3 times to 1.0 times the diameter of the most upstream pulley 202a of the second conveyor assembly 200, preferably from about 0.4 to about 0.6 times the diameter of the most upstream pulley 202a.

Alternatively, and preferably, as shown in Fig. 5A, a nose pulley 506 may be provided at the downstream end 507 of the infeed conveyor assembly 500. The nose pulley 506 may also be referred to herein as a "nose roller", since it has a substantially smooth surface. The nose pulley 506 may have a diameter which is significantly smaller than the diameter of the most upstream pulley 202a of the second conveyor assembly 200, to allow the infeed conveyor belt 501 to be brought into relatively close proximity to the second conveyor belt 201. In exemplary embodiments, the nose pulley 506 has a diameter which is from about 0.05 times to about 0.3 times the diameter of the pulley 202a, preferably from about 0.15 times to about 0.2 times the diameter of the pulley. The nose pulley 506 is positioned such that the axis of the nose pulley is higher in the z-direction than (above) the axis of the pulley 202a, such that, as noted above, there is a drop between the upper path of the infeed conveyer belt 501 and the path of the second conveyor belt 201.

The one or more pulleys 502 or 506 supporting the infeed conveyor belt 501 may have a substantially smooth surface (such that the one or more pulleys 502 or 506 do not comprise any teeth). Similarly a first surface 503 of the infeed conveyor belt 501 which is arranged to contact the one or more pulleys 502 may be substantially smooth. In this regard it is noted that, unlike the first and second conveyor assemblies 100, 200 in which the conveyor belts and pulleys advantageously have teeth in order to provide selected levels of torque and to help to reduce the appearance of castellations when compressing stacks of articles, toothed pulleys and belts may not be required for the infeed conveyor assembly 500 since stacks of articles are not compressed whilst travelling on the infeed conveyor assembly. Hence, in embodiments, the infeed conveyor assembly is configured such that a stack of articles is contacted only on one side by a single conveyor belt (which is the infeed conveyor belt 501). The second surface 504 of the infeed conveyor belt 501, which is arranged to contact a stack of articles in use, may be substantially smooth.

Furthermore, since the infeed conveyor assembly is not required to compress a stack of articles in use, the infeed conveyor belt 501 can be (and in an embodiment is) thinner than the second conveyor belt 201.

The infeed conveyor belt 501 may be driven by one or more drive pulleys (not shown) that contact the infeed conveyor belt 501.

As noted above, and as shown in Fig. 1, in order to remove a compressed stack of articles from the outfeed region 3 of the apparatus 700, an outfeed conveyor assembly 600 may be provided.

As shown in Fig. 1, the outfeed conveyor assembly 600 comprises an outfeed conveyor belt 601. The outfeed conveyor belt 601 is arranged downstream of (and adjacent to) the second conveyor belt 201 of the second conveyor assembly 200 in the machine direction, such that a stack of articles conveyed on second conveyor belt 201 may be transferred (directly) onto the outfeed conveyor belt 601.

The outfeed conveyor belt 601 may be supported by one or more pulleys (not shown) (and optionally, one or more other support elements such as support plates). The outfeed conveyor assembly 600 is configured such that an (upper) path of the outfeed conveyor belt 601 (on which a stack of articles is to be supported in use) extends substantially horizontally in the machine direction. The outfeed conveyor assembly 600 may comprise a suitable drive (e.g. motor) for driving the outfeed conveyor belt 601 such the upper surface of the path of the outfeed conveyor belt 601 moves in the machine direction.

The (upper) path of the outfeed conveyor belt 601 may be substantially aligned with the path of the second conveyor belt 201 in the z-direction, such that a stack of articles riding on (supported by) the second conveyor belt 201 can be transferred to the outfeed conveyor belt 601. Alternatively (and preferably) there is a drop between the path of the second conveyor belt 201 and the path of the outfeed conveyor belt 601, such that a stack of articles can drop slightly onto the outfeed conveyor belt 601 in use (has been found to help prevent a stack from being deformed during transfer to the outfeed conveyor belt 601).

The second conveyor belt 201 and the outfeed conveyor belt 601 should be positioned close to one another, so as to provide a relatively small gap between the second conveyor belt 201 and the outfeed conveyor belt 601. This may help to allow a stack of articles to be transferred from the second conveyor belt 201 to the outfeed conveyor belt 601 without becoming unstable or deforming.

However, as noted above, the most downstream pulley 202g of the second conveyor assembly 200 may advantageously have a relatively large diameter which may help to avoid excessive bending of the second conveyor belt 201 about that pulley, especially where the belt 201 is relatively rigid. As a result, it can be difficult to bring the outfeed conveyor belt 601 close to the second conveyor belt 201 in order to reduce the gap, which can help to reduce the chance of stack instability when a stack is transferred from the second conveyor belt 201 to the outfeed conveyor belt 601. Therefore, some intermediate arrangement may be used to bridge the gap. For example, a single pulley of a moderate size may be used to support the outfeed conveyor belt 601 at an upstream end of the outfeed conveyor belt 601, in combination with a plate (also referred to as a "dead plate") or other supporting element that bridges a gap between the pulley of the outfeed conveyor assembly 500 and the most downstream pulley 202g of the second conveyor assembly 200. In such an arrangement, in use, a stack of articles can ride on the plate or other supporting element when being transferred between the second conveyor belt 201 and the outfeed conveyor belt 601. As noted above, the pulley of the outfeed conveyor belt 601 may be of moderate size, e.g. having a diameter which is from about 0.3 times to 1.0 times the diameter of the most downstream pulley 202g of the second conveyor assembly 200, preferably from about 0.4 to about 0.6 times the diameter of the most downstream pulley 202g.

Alternatively, and preferably, as shown in Fig. 5B, a nose pulley 606 may be provided at the upstream end 607 of the outfeed conveyor assembly 600. The nose pulley 606 may also be referred to herein as a "nose roller", since it has a substantially smooth surface. The nose pulley 606 may have a diameter which is significantly smaller than the diameter of the most downstream pulley 202g of the second conveyor assembly 200, to allow the outfeed conveyor belt 601 to be brought into relatively close proximity with the second conveyor belt 201. In exemplary embodiments, the nose pulley 606 has a diameter which is from about 0.01 times to about 0.3 times the diameter of the pulley 202g, preferably from about 0.05 times to about 0.2 times the diameter of the pulley 202g. The nose pulley 606 is positioned such that the axis of the nose pulley is lower in the z-direction than (below) the axis of the pulley 202g, such that, as noted above, the upper path of the outfeed conveyor belt 601 is substantially in line with or slightly below (at a drop relative to) the path of the second conveyor belt 201.

Any pulley supporting the outfeed conveyor belt 601 may have a substantially smooth surface (such that those pulleys do not comprise any teeth). Similarly a first surface 603 of the outfeed conveyor belt 601 which is arranged to contact one or more pulleys may be substantially smooth. In this regard it is noted that, unlike the first and second conveyor assemblies 100, 200 in which the conveyor belts and pulleys advantageously have teeth in order to provide selected levels of torque and to help to reduce the appearance of castellations when compressing stacks of articles, toothed pulleys and belts may not be required for the outfeed conveyor assembly 600 since stacks of articles are not compressed whilst travelling on the outfeed conveyor assembly. Hence, in embodiments, the outfeed conveyor assembly 600 is configured such that a stack of articles is contacted only on one side by a single conveyor belt (which is the outfeed conveyor belt 601) when being conveyed through the outfeed conveyor assembly 600. The second surface 604 of the outfeed conveyor belt 601, which is arranged to contact a stack of articles in use, may be substantially smooth.

Furthermore, since the outfeed conveyor assembly 600 is not required to compress a stack of articles in use, the outfeed conveyor belt 601 can be (and in an embodiment is) thinner than the second conveyor belt 201.

The outfeed conveyor belt 601 may be driven by one or more drive pulleys (not shown) that contact the infeed conveyor belt 601.

It is also noted that a larger gap between the second conveyor belt 201 and the outfeed conveyor belt 601 may be tolerated then between the second conveyor belt 201 and the infeed conveyor belt 501, since the stack of articles may be more 'solid' and less prone to deform into the gap after having been compressed by travelling through the infeed region 1, compression region 2, and outfeed region 3 of the assembly.

Stack defects As mentioned above, the various components of the assembly may be arranged and adapted to help to reduce the occurrence of stack defects when a stack of articles is being mechanically compressed, and particularly when a naked (unpackaged) stack of articles are being compressed.

The types of defect which are of concern, include stack deformation (e.g. rhombussing), damage to articles within the stack (e.g. tearing), and indentations or other undesirable impressions (e.g. castellations) in a surface of the stack which contacts the compression belts. Such defects are illustrated and shown, in Figs. 11A-D.

Fig. 11A illustrates a side view along the cross-machine direction of a stack of articles 800a, such as a stack of tissues, prior to compression. Although Fig. 11A shows a certain number of articles (and hence layers) in the stack, in practice other numbers of articles could be used. In Fig. 11A the articles have been stacked such that the stack has a rectangular profile when viewed along the cross-machine direction.

Fig. 11 B shows a side view along the cross-machine direction of a compressed stack of articles 800b which has been deformed such that the profile is no longer rectangular. Such deformation can occur during compression of a stack of articles, and is a result of articles in the stack of articles moving relative to one another. Such relative movement can occur, for example, if the stack is subjected to any undesirable shear forces during compression. In the example of Fig. 11 B, when viewed from the cross-machine direction, the stack of articles has a profile which resembles a parallelogram having interior angles which are not 90 degrees. Although the profile is not strictly rhombus-shaped (since its sides are not necessarily of equal length), the general term for this type of shear deformation of a stack will be referred to herein as "rhombussing".

Fig. 11 C shows a stack of articles 800c (in this case a stack of tissues), wherein a top tissue 801c of the stack has become damaged when contacting a compression surface.

In the example of Fig. 11 C, the compression surface is a conveyor belt 801 supported by a pulley 802. As discussed above, such damage (e.g. tearing) can occur if the tissue undesirably sticks to the surface of the conveyor belt.

Fig. 11D shows a stack of articles 800d wherein a top surface of the stack of articles has undesirable impressions or indentations 802 (also referred to herein as "castellations") as a result of being compressed. Undesirable impressions or indentations 802 are also referred to herein as "castellations". Such castellations can be caused, for example, as a stack of articles passes between an opposed pair of toothed pulleys having teeth aligned in the cross-machine direction. Castellations caused by such toothed pulleys may accordingly extend in the cross-machine direction across the top surface of the stack.

Method In embodiments, there is provided a method of compressing a stack of articles, preferably using the compression apparatus 700 discussed above.

Hence, the method includes conveying a stack of articles through the infeed region 1, compression region 2, and outfeed region 3 of the compression apparatus 700.

In the method, a "pre-compressed" stack of articles refers to a stack of articles prior to passing through the apparatus (i.e. prior to passing through the infeed region 1, compression region 2, and outfeed region 3 of the apparatus), whereas a "compressed" stack of articles refers to a stack of articles after it is has passed through the apparatus (i.e. after passing through the infeed region 1, compression region 2, and outfeed region 3 of the apparatus). The "compressed" stack of articles may refer to the stack of articles immediately upon exiting the outfeed region 3, at which point, compared to the height of the stack whilst in the compression region 2, the stack of articles will have regained some of its pre-compressed height.

The method may comprise providing the (pre-compressed) stacks of articles to the compression apparatus 700 using a suitable infeed conveyor assembly (e.g. such as the infeed conveyor assembly 500 discussed above). The method may comprise conveying the compressed stack of articles away from the compression apparatus 700 using a suitable outfeed conveyor assembly (e.g. such as the outfeed conveyor assembly 600 discussed above), and packaging the compressed stack of articles.

The discussion herein will focus on stack of articles which are stacks of tissues, and particularly are "naked" stack of tissues which are not packaged prior to or during compression by the compression apparatus 700.

The tissues of the stack of tissues may each have one or more plies (and preferably either 2 or 3 plies). The tissues of the stack of tissues are preferably all substantially identical. The tissues of the stack of tissues may each be folded. Although the following will be described with relation to C-folded tissues, other types of fold could be used. Other suitable folds include, for example a J-fold, and a Z-fold The folded tissues may be placed on one top of the other in the stack. Alternatively, the tissues in the stack may be interfolded. When tissues are interfolded, a panel (or portion) of tissues in the stack may be positioned between two panels (or portions) of an adjacent tissue in the stack, such that panels (or portions) of the tissues are interfolded.

As used herein a "stack of tissues" means a stack of "tissue paper products", and similarly a "tissue" means a "tissue paper product". Tissue paper products may be any type of tissue paper product, including, although not limited to, a bathroom tissue, facial tissue or hand tissue.

However, it will be apparent that the method may apply equally to stacks of compressible articles that are not tissue paper products (and accordingly the compression apparatus 700 may be configured compress stacks of compressible articles that are not tissue paper products). For example, other types of compressible articles that may be compressed according to the method include, but are not limited to, sanitary napkins, pants, or other hygiene articles.

The steps of an exemplary embodiment of the method, in the case of a stack of C-folded tissues, are set out in Fig. 8. The steps comprise: 801 receiving a stack of tissues, wherein each tissue in stack has been C-folded; 802 rotating the stack of tissues to a predetermined orientation; 803 conveying the stack of tissues through the compression apparatus 700; and 804 packaging the stack of tissues. These steps are discussed in further detail below.

Although the method of Fig. 8 is described with respect to a single stack of tissues, plural stacks of tissues can be processed simultaneously according the method as a stream of stacks of tissues. Hence, the method may comprise continually receiving 801, rotating 802, conveying 803 through the compression apparatus, and packaging 804 stacks of tissues. In this manner, at any given time, plural stacks 900 of tissues 901 may be being conveyed through the compression apparatus 700, as shown in Fig. 7 for example. Hence, with reference to Fig. 9, according to the method, tissues may sequentially pass through: a folding assembly 901 (in which each tissue is folded into a C-fold); a stacking assembly 902 (in which the C-folded tissues are stacked into a stack of tissues); a rotation assembly 903 (in which the stack of tissues are rotated to a pre-determined orientation) an infeed conveyor assembly 500 (as discussed above, which conveys the stack of tissues towards the compression apparatus 700); the infeed region 1, compression region 2 and outfeed region 3 of the compression apparatus 700; an outfeed conveyor assembly 600 (as discussed above, which conveys the compressed stack of tissues away from the compression apparatus 700), and a packaging unit 904 (in which the compressed stack of tissues are packaged).

As discussed above, the method comprises receiving 801 a stack of tissues, wherein each tissue in stack has been C-folded.

Fig. 9A shows a tissue 901 prior to folding (i.e. in a non-folded state). The tissue has a rectangular shape having a first dimension D1 and a second dimension D2. The first and second dimensions D1, D2 extend perpendicular to one another. Mutually opposing first and second ends 902a, 902b of the tissue are parallel to one another and extend in the direction of the first dimension Di of the tissue, whilst mutually opposing third and fourth ends 902c and 902d are parallel to one another and extend in the direction of the along the second dimension D2 of the tissue.

Figs. 9B and 9C respectively show a top view and a side view of the tissue 901 after it has been folded into a C-fold.

The C-fold is formed by folding the first end 902a and the second end 902b towards the centre of the tissue. The folding of the first and second ends 902a, 902b is performed along fold lines (shown as dashed lines in Fig. 9A) in order to form respective folded edges 903a, 903b. In the folded condition, the folded edges 903a, 903b lie parallel to one another, and parallel to the first and second edges 902a, 902b. The folded tissue has a first dimension Dio which extends between the folded edges 903a, 903b. The folded tissue has a second dimension Dio which extends along the direction of the folded edges 903a, 903b. Hence, the folded tissue comprises a first panel 910a and a second panel 910b which are superposed on a base panel 911, such that the first panel 910a and the second panel 910b each overly a portion of the base panel 911. The first panel 910a extends between the end of the tissue 902a and the folded edge 903a. The second panel 910b extends between the end of the tissue 902b and the folded edge 903b. The base panel 911 extends between the folded edges 903a, 903b.

As a result of the folding of the tissue, a first region 904a of the folded tissue in which the first panel 910a superposes the base panel 911 consists of two layers of tissue material. Similarly a second region 904b of the folded tissue in which the second panel 910b superposes the base panel 911 consists of two layers of tissue material. A central region 905 where the base panel 911 is superposed by neither of the first panel 910a and second panel 910b consists of only one layer of tissue material. Hence, the number of layers of tissue material varies along the first dimension D10 of the folded tissue. However, at any point along the first dimension Dm, the number of layers of tissue material does not vary along the second dimension D20 of the folded tissue. Since each layer of tissue material has an associated thickness, the thickness of the tissue accordingly varies along the first dimension Dia, However, a maximum thickness of the folded tissue along the first dimension Dio is the same at each point along the second dimension D20. The variation of thickness of the folded tissue may be referred to herein as a "thickness profile".

After plural tissues have been C-folded, a stacking assembly 902 stacks plural folded tissues 901 into a stack 900. Figs. 9D and 9E respectively show a top view and a side view of a stack 900 of folded tissues 901. The top view of the stack in Fig. 9D is substantially the same as the top view of a single tissue in Fig. 9B.

As shown in Fig. 9E, in the stack, each of the tissues 901 is oriented in the same direction, such that the folded edges 904a and 904b of the tissues in the stack are all aligned with one another.When viewed from above, the stack has a first dimension Dii which corresponds to the first dimension Dio of the top tissue in the stack, and a second dimension D22 which corresponds to the second dimension D20 of the top tissue in the stack.

The first, second and central regions 904a, 904b and 905 of each tissue 901 in the stack is aligned with the first, second and central regions 904a, 904b and 905 of any tissues below in the stack to form respective first, second and central regions 906a, 906b and 907 of the stack 900. Accordingly, the first and second central regions 906a, 906b f the stack consist of more layers of material than the central region 907 of the stack.

Hence, due to the thickness profile of the folded tissues 901 in the stack 900, the stack also has a thickness profile. In particular, the thickness (height) of the stack 900 varies along the first dimension Dii.However, a maximum thickness (height) of the stack 900 along the first dimension D11 is the same at each point along the second dimension D22 of the stack.

After the stack has been formed in the stacking assembly 902, the stack of tissues is provided to a rotation assembly 903 which rotates the stack to a predetermined orientation before the stack is provided to the compression apparatus 700 (via the infeed conveyor assembly 500) in that same predetermined orientation.

In this regard, it has been found that the orientation of the stack of folded tissues as it enters (and is conveyed through) the compression apparatus 700 can affect stack stability, and can influence the occurance of stack defects (e.g. such as tearing or other damage to the tissues in the stack, and rhombussing). For example, it was found that, for C-folded tissues, if the stacks of tissues were provided to the compression apparatus 700 with a folded edge leading (i.e. with the folded edges 903a and 903b aligned in the cross-machine direction), then castellation and stack stability worsened. This may be due to the fact that, in this orientation with a folded edge leading, the thickness of the stack varies in the machine direction as the stack passes through the compression apparatus 700 (since a relatively thicker first portion 906a is first presented, then a thinner central portion 907, followed by the thicker second portion 906b).

Hence, in order to help to reduce castellation and improve stability of a stack of folded tissues, the stack of folded tissues may be rotated to a predetermined orientation before being provided to the compression apparatus 700.

In embodiments of the present method, the stacks 900 of C-folded tissues 901 are provided to the compression apparatus 700 in an orientation such that the second dimension D22 aligned in the machine direction. This is illustrated in Fig. 9F. Fig. 9F is a top view of the stacks 900 of folded tissues positioned (supported) on the second conveyor belt 201 as the stacks 900 approach a pulley 102 of the compression assembly (wherein the pulley 102 may be any of the pulleys of the compression region 2).

As a result of the orienting the second dimension D22 in the machine direction, as the stacks 900 progress through the compression apparatus 700, at an given time, the maximum thickness of a part of a stack of articles that is contacted by the apparatus 700 does not change. More particularly (as can be seen that for stacks of C-folded tissues for example), at a given position in the cross-machine direction, the thickness of each stack of articles 900 does not vary in the machine direction. The consistent maximum thickness when contacted by the compression apparatus can help to maintain stack stability as each stack progresses through the compression apparatus.

The thickness of each stack of articles 900 does vary along the cross-machine direction (since the first dimension Dii is aligned with the cross-machine direction). However, it has been found that variation of the thickness profile in the machine direction may be preferable to a variation of the thickness profile in the machine direction. In particular, it has been found that stack stability may still be maintained even if there is some variation in stack thickness in the cross-machine direction.

In other words, each stack is oriented such that the folded edges 903a, 903b of the C-folded tissues are aligned in the machine direction. In this manner, the thinner central portion 907 is between the thicker first and second portions 906a, 906b in the cross-machine direction, such that the thickness (height) of the stack varies in the cross-machine direction. However, at a given position in the cross-machine direction the height of the stack does not change along the machine direction.

The rotation assembly 903 may be required to rotate the stack of folded tissues by 90 degrees to achieve the desired pre-determined orientation. The amount of rotation required depends on the orientation in which the stacks of tissues leave the stacking assembly 902.

Although the above is described with respect to a C-fold, similar principles will apply if other types of fold are be used. Hence, the tissues may be provided to the compression apparatus in an orientation in which, at any given position in the cross-machine direction, the thickness (height) of the stack is substantially the same in the machine direction along the stack. For example the tissues may be oriented such that the number of layers of tissue material making up the stack is substantially the same along the machine direction. The thickness (height) of the stack can, however, vary in the cross-machine direction..

Furthermore, although the above is described with respect folded tissues, similar considerations may apply when compressing stacks of other types of articles. In this case, the stacks of articles may be oriented such that (at any point in the cross machine direction) a maximum thickness (height) of each stack does not vary in the machine direction. The thickness of the stack may, however, vary in the cross-machine direction.

While embodiments have been described in which include article folding and article stacking assemblies, the compressing apparatus described herein need not be included in a line incorporating such assemblies. Either or both of these processes may be performed off-line. The compression apparatus may then operate on stacks of articles supplied thereto in any manner, whether or not folded. The system may, for example, include only an article stacking assembly, or both an article stacking assembly and article folding assembly, or neither of these.

It will be appreciated that it may not be necessary to rotate stacks of tissues to result in the stacks entering the infeed region with the desired orientation, depending upon the orientation of the stacks when produced or received (whether or not article folding or stacking occurs inline). However, it is desirable that the stacks of articles enter the infeed region of the compression apparatus with the preferred predetermined orientation described above (i.e. with a second dimension along the machine direction). Thus, broadly, embodiments of the method of the invention may involve supplying stacks of articles e.g. folded articles, to the infeed region with the above described predetermined orientation. It has been found that this orientation surprisingly improves stack stability and reduces castellation effects. In the context of stacks of folded articles, in which the predetermined orientation has folded edges along the machine direction, this is counter intuitive, as it might be expected that improved properties might instead have arisen from inserting stacks into the compression region with folded edges leading.

Each stack 900 of tissues is provided to the compression apparatus 700, and directed along a path which proceeds sequentially through the infeed region 1, compression region 2, and outfeed region 3 in the machine direction. In particular, the stack 900 is received on (and conveyed on) the lower conveyor belt 201 through the infeed region 1, compression region 2, and outfeed region 3, each stack 900, wherein the lower conveyor belt 201 is driven by a suitable drive (e.g. a servomotor 205).

Plural stacks 900 of tissues may be conveyed through the compression apparatus 700 at the same time, as shown in Fig. 7.

Whilst the stacks 900 are being conveyed on the lower conveyor belt 201 (i.e. whilst the lower conveyor belt 201 is being driven), the upper conveyor belt 101 (which contacts an upper surface of each stack 900 for at least part of the path of the stack 900 in order to compress the stack) is also driven.

In an embodiment, the speed and/or position of the upper and lower conveyor belts 101, 201 is monitored as the stacks of articles 900 are conveyed through the compression apparatus 700. The monitoring may be performed by a controller, in response to signals -91 -received from the sensors (e.g. sensors of each of the servomotors 105, 205 that respectively drive the upper and lower conveyor belts 101, 201).

The speed and/or position of the upper and lower conveyor belts 101, 201 may be independently controlled. The speed and/or position of either or both of the upper and lower conveyor belts 101, 201 may be controlled by the controller in response to the monitoring, e.g. to ensure that the speed and/or position does not drift from a target value whilst the compression apparatus is running.

The method may comprise driving the upper and lower conveyor belts 101, 201 at substantially the same speed as one another through the compression region 2.

Alternatively, the upper and lower conveyor belts 101, 201 may be driven such that there is a speed differential between the upper and lower conveyor belts 101, 201. The relative speed of the upper and lower conveyor belts 101, 201 may be selected in order to try to reduce rhombussing of the stack of tissues as the stack of tissues is conveyed on its path through the compression apparatus 700 between the upper and lower conveyor belts 101, 201. The exact speeds required may depend on various characteristics of the stack of tissues, such as the pre-compressed height of the stack, the material of the tissue, and the number of plies in each tissue. The required speeds may be determined (or adjusted) based on a quality (e.g. amount of rhombussing) observed in stacks of tissues which have been compressed by the compression apparatus 700.

Whilst the compression apparatus 700 is running (whilst stacks of articles are present in the compression apparatus 700), the speed of each of the upper and lower conveyor belts 101, 201 may be greater less than or equal to 50m/min, preferably less than 40 m/min. The speed of each of the upper and lower conveyor belts 101, 201 may be greater than 20m/min, preferably greater than 30m/m.

The method may comprise determining a suitable infeed angle a for the infeed region 1. The infeed angle a may be selected in order to try to reduce the occurrence or severity of defects (e.g. such as rhombussing) in stacks 900 that have been compressed by the compression apparatus 700. For example, the infeed angle a may be selected based on an observed quality of stacks of tissues which have been compressed by the compression apparatus 700. The infeed angle a may be selected based on trial and error.

The infeed angle a may be selected to influence a rate at which the stacks 900 are compressed as they are conveyed through the infeed region 1 to the compression region 2. For instance, a larger infeed angle a corresponds to more steeply inclined plane 106 of the upper conveyor belt, and hence a more rapid rate of compression of a stack 900 as it is conveyed through the infeed region 1.

The infeed angle a may be selected to set a location at which the upper conveyor belt 102 contacts the stack 900 as the stack 900 is conveyed through the infeed region 1. For instance, a larger infeed angle a will result in a stack being contacted by the upper conveyor belt 102 closer to the compression region 2. Hence, the infeed angle a may be selected to set a distance over which a stack is conveyed whilst in contact with the upper conveyor belt 102. For example, the infeed angle a may be selected depending on the height of stacks to be compressed. For example, the infeed angle a may be adjusted such that (no matter what height that stack has), the stacks contact the upper conveyor belt 102 at the same location along the path of the stacks.

The infeed angle is adjusted when the compression apparatus 700 is not running. Hence, the infeed angle is adjusted whilst the upper and lower conveyor belts 102, 201 are stationary (not being running). The infeed angle may be adjusted may be adjusted whilst no stacks of tissues are in the compression apparatus 700. Hence, the infeed angle is maintained at a constant value whilst the apparatus is running..

The method may comprise determining a size (height) of the compression gap 114 for the compression region 2. The size (height) compression gap corresponds to the minimum height to which a stack 900 of tissues is compressed as is it is conveyed through the compression apparatus 700. The size (height) of the compression gap may be selected based on a height of a stack of articles that is required after the stack has exited the compression apparatus 700 (also referred to herein as the "post-compressed" height of a stack of articles). Selection of the compression gap size (height) may account for an amount by which the height of a stack of articles will recover as the stack of articles is conveyed through the outfeed region 3.

For example, the height of the compression gap may be selected based on at least one of: the pre-compressed height of a stack of articles to be received by the compression apparatus 700, the post-compressed height of a stack of articles required once the stack of articles has exited the compression apparatus 700, and a desired relative height between a stack of articles in its pre-compressed state (before being received by the compression apparatus 700) and its post-compressed state (after exiting the compression apparatus 700). For instance, it has been found that reducing the compression gap generally reduces the height of the stack of tissues in its compressed state after exiting the compression apparatus 700.

The compression gap 114 may be adjusted by whilst the compression apparatus 700 is not running. Hence, the compression gap 114 is adjusted whilst the upper and lower conveyor belts 102, 201 are stationary (not running). The compression gap 114 may be adjusted whilst no stacks of tissues are in the compression apparatus 700. Hence, the compression gap 114 is maintained at a constant value whilst the apparatus is running.

The method may comprise determining a suitable outfeed angle 3 for the outfeed region 3. The outfeed angle p may be selected in order to help the occurrence or severity of defects (e.g. such as rhombussing) in stacks 900 that have been compressed by the compression apparatus 700. For example, the outfeed angle p may be selected based on an observed quality of stacks of tissues which have been compressed by the compression apparatus 700. The outfeed angle [3 may be selected based on trial and error.

The outfeed angle 13 may be selected to influence the rate at which pressure is release from the stacks 900 they are conveyed through the outfeed region 3. For instance, a larger outfeed angle 13 corresponds to a more steeply inclined plane 110 of the upper conveyor belt, and hence a more rapid decrease in the pressure applied to a stack 900 as it is conveyed through the outfeed region 2.

Generally, smaller outfeed angles may reduce the effect of rhombussing and also reduce the occurance of tears in the upper tissues of a stack 900, since the transition between the compression region 2 and the compression region 3 is more gradual when the outfeed angle 13 is smaller.

The outfeed angle 13 is adjusted when the compression apparatus 700 is not running. Hence, the outfeed angle 13 is adjusted whilst the upper and lower conveyor belts 102, 201 are stationary (not running), and whilst no stacks of tissues are in the compression apparatus 700. Hence, the outfeed angle 13 is maintained at a constant value whilst the apparatus is running (whilst one or more stacks 900 are present in outfeed region 3). Hence, preferably, the method comprises conveying one or more stacks of tissues along a path through the compression apparatus, whilst maintaining a constant infeed angle 13, a constant height of the compression gap 114, and a constant outfeed angle 13. Hence, the each of the pulleys that support the upper and lower conveyor belts 101, 201 is maintained at a same (fixed) position as one or more stacks of tissues are conveyed along a path through the compression apparatus 700 defined between the upper and lower conveyor belts 101.

Preferably the stack of articles is sized so that a stack of articles 900 can fit entirely within the compression region 2. Hence, the length Li of a stack of articles in the machine direction is less than a length of the compression region 2 in the machine direction (and similarly, a width Wi of a stack of articles in the cross-machine direction is less than a width of the compression region 2 in the cross-machine direction). The method may comprise plural stacks of tissues to the compression apparatus as a stream of stacks of tissues.

Therefore, plural stacks of tissues may be present along the path defined between the upper and lower conveyor belts 101, 201 at any given time during a compression run (e.g. as shown in Fig. 7). The stacks 900 may be spaced apart in the machine direction. The spacing of stacks 900 in the machine direction can be such that more than one stack can fit within any of the infeed region 1, compression region 2, and outfeed region 3. Hence, it is not necessary to have only a single stack in the infeed region 1, compression region 2, or outfeed region 3 at any given time.

After a stack 900 of tissues exits the compression apparatus 700, it is may be directed to an outfeed conveyor assembly 600. The outfeed conveyor assembly may comprise a conveyor belt 601 on which the stack is supported, and which is drive so as to convey the stack in the machine direction away from the outfeed conveyor assembly 600. After a stack 900 of tissues exits the compression apparatus 700 it may be packaged into packing by a suitable packaging unit. The packaging may comprise a container, which may be rigid, e.g. such as a box constructed of paper, plastic, or card (and preferably being constructed of card). Figs. 10A and 10B show example boxes. The stack of tissues 900 may be slidably inserted into the suitable box 1000 as shown in Fig. 10A. Alternatively, the box could be provided around the tissues in any other suitable manner.

The compression apparatus 700 may be configured (set up) to ensure that the compressed stack of tissues that exits the compression apparatus 700 will fit into the packaging (e.g. by selecting or adjusting at least one of the infeed angle a, the height of the compression gap 114, the outfeed angle 8, and the speed at which the upper and lower conveyor belts 101, 201 are driven). Although, the varying the speed of the upper and lower conveyor belts 101, 201 may have a lesser effect on the final height of the stacks compared to varying the infeed angle a, the height of the compression gap 114, the outfeed angle II The compression apparatus 700 should therefore be configured to sufficiently compress the stack of tissues to fit into the desired packaging, but without excessively compressing the stack of tissues (since greater compression will exert unnecessary load on the pulleys and other structures of the compression apparatus 700). Preferably, compression apparatus 700 is configured such that, after exiting the compression apparatus 700, the height of a compressed stack of tissues will not increase further by any significant amount (otherwise, this could affect the ability to package the stack of articles, or create undesirable pressure within the packaging after the stack of articles has been packaged).

However, to allow for any small amounts of height gain ("spring back") that may occur after a stack of tissues has exited the outfeed region 3 of the compression apparatus 700, the compression apparatus 700 may be configured to compress the stack of tissues to a post-compressed height which is (slightly) less than the height of a box into which the tissues will be packed. For example, on exiting the compression apparatus 700, the post-compressed height of a stack of tissues may be from about 70% to 100% of the height of a box into which the tissues will be packed, preferably from about 80% to 95% of the height of a box into which the tissues will be packed.

For example, on exiting the compression apparatus 700, the stack of tissues may have a post-compressed height which is from about 2mm to about 10mm less than the height of a box into which the tissues will be packed, preferably about 5mm less than the height of the box.

The post-compressed height of a stack of tissues on exiting the compression apparatus 700 may be from about 10 mm to about 70mm, preferably from about 20 mm to about 60 mm.

The pre-compressed height of the stack of tissues prior to entering the compression apparatus 700 may be from about 70 mm to about 150 mm, preferably from about 100 mm to about 130 mm.

The post-compressed height will be less than the pre-compressed height. For example, the post-compressed height may be between 10% and 80% of the pre-compressed height, preferably between 20% and 70% of the pre-compressed height.

Preferably, the stack of tissues is not subjected to any further compression after exiting the compression apparatus 700, and before being packaged.

The above method has been described with respect to compressing a stack of tissues. However, the method similarly applies to other stacks of articles, and particularly to stacks of articles wherein the stack (and also the individual articles) are unpackaged whilst being conveyed through the compression apparatus 700.

In additional to compressing a stack of tissues, it has been found that the compression apparatus 700 may also produce a calendering effect that softens the tissues.

The calendering effect may be due to the compression occurring between upper and lower conveyor belts 102, 202 as the stack of tissues is conveyed in the machine direction. It has also been found that other quality parameters were not adversely affected to a degree where the customer would notice. For example, in use, the compression apparatus 700 may not noticeably worsen the absorbency or strength of the tissues in a stack of tissues.

While the methods above have been described in relation to an apparatus of the type earlier described, having first and second endless conveyor belts which define the infeed, compression and outfeed regions, in some broader aspects, it is envisaged that the opposed belt portions providing the infeed, compression and outfeed regions could be provided by opposed portions of any one or ones of sets of one or more conveyor belts on either side of the path of the stacks of articles, and not necessarily by the same pair of belts.

Although the present disclosure has been described with reference to various embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.

Claims

1. A method of compressing unpackaged stacks of articles using an automated apparatus for compressing stacks of articles, wherein the apparatus defines an infeed region, a compression region and an outfeed region, and is arranged to convey stacks of articles along a path in a machine direction in use sequentially through the infeed region, compression region and outfeed region, wherein the apparatus comprises one or more endless conveyor belts on one side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region and one or more endless conveyor belts on an opposite side of the path along which the stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region; the method comprising; supplying stacks of articles to be compressed to the infeed region of the apparatus; and operating the apparatus such the stacks of articles are conveyed along a path in the machine direction sequentially through the infeed region, compression region and outfeed region; wherein the infeed region, compression region and outfeed region of the apparatus are each defined between respective opposed portions of the paths of ones of the conveyor belts on either side of the path along which the stacks move through the infeed region, compression region and outfeed region in the machine direction, wherein the opposed portions of the paths of the conveyor belts defining the outfeed region diverge from one another along the machine direction.

2. The method of claim 1 wherein the opposed portions of the paths of the endless conveyor belts defining the outfeed region diverge from one another in the outfeed region so as to define an outfeed angle corresponding to an angle of divergence of the paths of the endless conveyor belts along the machine direction in the outfeed region, wherein the outfeed angle is in the range of from about 5 degrees to about 45 degrees, or optionally in the range of from about 5 degrees to about 15 degrees.

3. The method of any preceding claim wherein the opposed portions of the paths of the first and second endless conveyor belts converge with one another along the machine direction in the infeed region.

4. The method of claim 4 wherein the opposed portions of the paths of the endless conveyor belts defining the infeed region converge with one another in the infeed region along the machine direction so as to define an infeed angle corresponding to the angle of convergence of the paths of the endless conveyor belts in the infeed region, wherein the infeed angle is in the range of from about 5 degrees to about 45 degrees, or optionally in the range of from about 5 degrees to about 20 degrees.

5. The method of any preceding claim wherein the opposed portions of the paths of the endless conveyor belts defining the compression region extend substantially parallel with one another along the machine direction, or wherein the opposed portions of the paths of the endless conveyor belts defining the compression region converge with one another along the machine direction.

6. The method of claim 5 as dependent upon claim 3 or claim 4, wherein the opposed portions of the paths of the conveyor belts defining the compression region converge with one another along the machine direction, wherein the paths of the conveyor belts defining the infeed region converge with a first angle of convergence in the infeed region, and wherein the paths of the conveyor belts defining the compression region converge with a second angle of convergence in the compression region, wherein the first angle of convergence is greater than the second angle of convergence.

7. The method of any preceding claim wherein the endless conveyor belts defining the compression region are spaced from one another in the compression region to provide a compression gap, optionally wherein a size of the compression gap is in the range of from about 2mm to about 75 mm, or from about 5mm to about 50mm.

8. The method of any preceding claim wherein the apparatus comprises a first endless conveyor belt on one side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region, and a second endless conveyor belt on an opposite side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region, wherein the infeed region, compression region and outfeed region are each defined between respective opposed portions of the paths of the first and second endless conveyor belts on either side of the path along which stacks of articles move in the machine direction in use through the infeed region, compression region and outfeed region, wherein the respective opposed portions of the paths of the first and second endless conveyor belts defining the outfeed region diverge from one another along the machine direction.

9. The method of claim 8 wherein the first endless conveyor belt forms part of a first conveyor assembly, the first conveyor assembly further comprising a plurality of pulleys around which the first endless conveyor travels when traversing the first endless conveyor belt path, and the second endless conveyor belt forms part of a second conveyor assembly, the second conveyor assembly further comprising a plurality of pulleys around which the second endless conveyor belt travels as it traverses the second endless conveyor belt path" the apparatus further comprising a driving arrangement for driving the first and second endless conveyor belts along their respective paths.

10. The method of claim 9 wherein the first and second endless conveyor belts of the first and second conveyor assemblies are independently drivable, and the driving arrangement comprises first and second independently operable driving arrangements for driving the first and second endless conveyor belts respectively, wherein the first driving arrangement comprises a first servomotor arranged to drive a drive pulley of the first conveyor assembly, and the second driving arrangement comprises a second servomotor arranged to drive a drive pulley of the second conveyor assembly, wherein each servomotor comprises a motor, sensing circuitry for sensing one or more parameters of the motor indicative of a speed of the motor, circuitry for comparing the speed of the motor to a target speed of the motor, and circuitry for controlling the speed of the motor based on the results of the comparison, wherein the method comprises setting the target speed of the motor in order to achieve a given speed of the endless conveyor belt of the respective conveyor assembly with which the drive pulley driven by the servomotor is associated.

11 The method of any one of claims 8 to 10 wherein the first endless conveyor belt is located above the second endless conveyor belt in the infeed, compression and outfeed regions, wherein the path of the second endless conveyor belt extends horizontally through the infeed, compression and outfeed regions for supporting stacks of articles as they travel through the infeed, compression and outfeed regions, and the path of the first endless conveyor converges with the path of the second endless conveyor belt in the infeed region, extends substantially parallel to the path of the second endless conveyor belt in the compression region or converges with the path of the second endless conveyor belt less steeply than in the infeed region, and diverges from the path of the second endless conveyor belt in the outfeed region.

12. The method of any one of claims 8 to 11 wherein the first and second conveyor assemblies comprise respective first and second sets of compression region pulleys for guiding the first and second endless conveyor belts respectively in the compression region and providing a compression force on stacks of articles passing through the compression region, wherein each one of the first and second sets of compression region pulleys comprises a plurality of pulleys spaced along machine direction.

13. The method of any one of claims 8 to 12 wherein the first endless conveyor belt travels around a pulley to change a direction of the path of the belt at a transition between the compression and outfeed regions, optionally wherein the first endless conveyor belt defines a wrap angle with the pulley of less than 120 degrees, or less than 90 degrees, or less than 60 degrees; and/or wherein the first endless conveyor belt travels around a pulley to change a direction of the path of the belt at a transition between the infeed and compression regions, optionally wherein the first endless conveyor belt defines a wrap angle with the pulley of less than 120 degrees, or less than 90 degrees, or less than 60 degrees.

14. The method of any preceding claim wherein the stacks of articles contact the facing surfaces of both of the opposed belts between which the respective region is defined throughout the compression region, and along at least an upstream portion of the outfeed region, and optionally along at least a downstream portion of the infeed region.

15. The method of any preceding claim comprising operating the apparatus such that compressed stacks of articles cease to contact the facing surfaces of both of the opposed belts in the outfeed region at a point upstream of a downstream end of the outfeed region, wherein the point is upstream of a downstream-most pulley of the outfeed region about which one of the endless conveyor belts forming part of the outfeed region turns to commence a return portion of its path at the end of the outfeed region.

16. The method of any preceding claim comprising driving each of the endless conveyor belts at a speed of greater than 20m/min or greater than 30 m/min.

17. The method of any preceding claim wherein the compression region has a length greater than or equal to, and preferably greater than, a length of each stack of articles to be compressed along the machine direction.

18. The method of any preceding claim wherein the method further comprises packaging the compressed stacks of articles downstream of the outfeed region.

19. The method of any preceding claim wherein the step of packaging the compressed stacks of articles comprises packaging each stack of articles in a rigid container.

20. The method of claim 19 wherein packaging articles into a rigid container comprises inserting the stacks of articles into the container through an opening and then closing the container, wherein the method comprises compressing the stacks of articles to a compressed height which is from about 70% to about 100%, or optionally from about 80% to -100 -about 95% of a height of the opening in the container through which the compressed stack of articles is inserted when packaging the compressed stack of articles.

21. The method of any preceding claim wherein the length of the infeed region and the length of the outfeed region are both greater than a length of the compression region, optionally wherein the length of the outfeed region is less than a length of the infeed region.

22. The method of any preceding claim wherein the stacks of articles which are compressed using the apparatus have a thickness which varies along a first dimension of the stack and a maximum thickness that is constant along a second dimension of the stack, wherein the method comprises introducing each stack of articles to the compression region in a predetermined orientation with the second dimension of the stack, along which the maximum thickness of the stack is constant, oriented along the machine direction.

23. A method of compressing unpackaged stacks of folded articles; the method comprising; providing stacks of articles, wherein the stacks of articles have a thickness which varies along a first dimension of the stack and a maximum thickness that is constant along a second dimension of the stack, and supplying the stack of folded articles to a compression region for compressing the stack of folded articles in a predetermined orientation with the second dimension of the stack oriented along the machine direction.

24. The method of claim 22 or claim 23 further comprising reorienting the stacks of articles before they enter the compression region to result in the stacks of articles being in the predetermined orientation, optionally wherein the stacks of articles are reoriented from an initial orientation in which the stacks of articles have their first dimension along the machine direction.

25. The method of claim 24 as dependent upon claim 22 wherein the reorientation of the stacks of articles occurs upstream of the infeed region of the apparatus.

26. The method of any one of claims 22 to 25 wherein the thickness of each stack of articles varies at different points across the first dimension of the stack so as to provide the stack with a thickness profile across a first dimension thereof, wherein at any given point along the second dimension of the stack, the stack exhibits the same thickness profile across the first dimension thereof -101 -

27. The method of claim 26 wherein the articles are folded articles, wherein the thickness profile of the stack results from differing numbers of layers of the material of the articles being present in the stack at different points across the first dimension thereof, optionally wherein the differing numbers of layers are the result of a folding configuration of the articles and/or a method of interfolding of the articles.

28. The method of any one of claims 22 to 27 wherein the stacks of articles are stacks of folded articles, wherein each article comprises folded edges, the folded edges being aligned along a second dimension of the stack.

29. The method of any preceding claim wherein the stacks of articles are stacks of tissue paper products.

30. The method of claim 29 wherein the articles are folded tissues, such as C-folded tissues.

31. The method of any one of claims 1 to 29 wherein the stacks of articles are stacks of articles other than tissue paper products.