GB2590432A

GB2590432A - Flow wrap packaging machine

Info

Publication number: GB2590432A
Application number: GB1918642.8A
Authority: GB
Inventors: Sidney Turner Richard; Marlee John
Original assignee: Bradman Lake Ltd
Current assignee: Bradman Lake Ltd
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2021-06-30
Anticipated expiration: 2039-12-17
Also published as: GB201918642D0; GB2590432B

Abstract

An end sealing apparatus for a flow wrap packaging machine comprising a cam track 1301. A plurality of carriages (fig 5 1507) follow the cam track each with a drive means (fig 5 700) to independently drive each carriage. Preferably the carriages may be driven at variable speeds. Optionally the end sealing apparatus may comprise a second cam track with a second plurality of carriages (fig 5 1508). This second track may lie parallel to the first. Each carriage of the first track may be paired with a corresponding carriage from the second track, this pair of carriages may be synchronised. Also disclosed is an end sealing apparatus for a flow wrap packaging machine, comprising a pair of carousels each with a set of carriages, a first drive means for driving the first carriage on both carousels, and a second drive means for driving the second carriage on both carousels. Each drive means is independently controllable.

Description

FLOW WRAP PACKAGING MACHINE

Field of the Invention

[0001] The present invention relates to packaging machines, and particularly although not exclusively to flow wrap packaging machines.

Background of the Invention

[0002] Conventional flow wrap packaging machines are used for packaging a wide range of consumer, household and retail items, such as food items and pharmaceutical items, industrial components and the like.

[0003] A conventional flow wrapping machine as used in particular for wrapping food items, such as biscuits, pizzas, sachets of liquids, and other consumable food items, receives a continuous stream of individual items to be packaged, and encapsulates these items in a single web of wrapping material, which can be plastics, paper, waxed paper or like sheet material. Typically a single web of material is folded over, so that one side of the sheet faces an opposite side. An item to be packaged is inserted into the sheet, and the lateral edges of the sheet are bonded together along the direction of the sheet. The sheet of material, containing the item to be packaged is then fed into an end sealing stage which seals both ends of the package, and cuts the package from the rest of the web of material.

[0004] Other known flow wrap packaging machines use two webs of packaging material which may be the same material, or of different material types.

In these machines, sealing of packages occurs on four sides of each package. Such machines include horizontal rotary four side sealing machines for packaging items such as medicines, medical devices or pharmaceutical products.

[0005] Where the packages are printed, the web of material may be printed with a repeating artwork pattern, and it is important that the items to be packaged are fed into the sheet of packaging material synchronised with the pattern of the material sheet and that the end crimping occurs between adjacent repetitions of the pattern, so that when packaged, the ends of the package are correctly aligned with the artwork pattern on the finished package.

[0006] Referring to Figure 1 herein, there is illustrated schematically in perspective view a known packaged food item which has been packaged using a known flow wrap machine using a single web of packaging material folded over to create a continuous stream of packages sealed on three sides. The package 100 comprises a single sheet of material cut from an elongate web of material, and which is folded over one or more content items so that perimeter regions of the first and second opposing sides are sealed to each other, forming a tube 101. Each end 102, 103 of the tube is sealed using a crimp seal by pressing the tube flat which seals the sheet of material to itself. At the same time as sealing the ends of the tube, the package is cut from the web of material using a knife blade incorporated into the crimp heads of the flow wrap machine.

[0007] In the example package shown, the ends of the package are cut in a serrated pattern, and the crimp head has a plurality of ridges and valleys which extend in a direction transverse to the main length of the package. In the first example package, the depth of the package is thin enough that there is no need to tuck in the ends of the sheet material before crimping the ends of the package.

[0008] Referring to Figure 2 herein, there is illustrated schematically a second example of a prior art package 200 created on a prior art flow wrap machine in view from one side. In the second example package, the package is of sufficient depth that the ends of the package need to be tucked in towards the centre line of the package before crimping the ends of the package. This requires an additional operation to push in the sides of the package towards the centre of the package at each end portion in order to create end tucks 201, 202. An end tuck may be applied to the end of the package immediately before creating the end seal where the package is deep enough that end tucks are needed.

[0009] Referring to Figure 3 herein, there is illustrated schematically in view from an underside, a third example prior art package 300. The package comprises a single sheet of material folded over into a tubular rectangular shape and sealed with a longitudinal seal 301 which runs along a main length of the package; the package having first and second ends 302, 303, each of which is sealed by crimping the sides of the tubular sheet. The longitudinal seal 301 is folded flat as the ends of the package are crimped together.

[0010] Known flow wrap packaging machines typically have the following 10 stages: * a product collating stage in which one or a plurality of products are collated onto a transport conveyor, with the products either are individually spaced apart from each other if they are to be individually packaged, or a plurality of products collated together into a bundle if a plurality of products are to be packaged together in the same package; * a longitudinal sealing section in which the items to be packaged are fed into a continuously moving web of packaging sheet material and aligned with any repeat pattern printed artwork on the sheet of packaging material, so that the product lies between any printed end seal areas of the printed artwork; * an end sealing section where the ends of each packet are sealed and each individual packet is cut or detached from the web of material so as to form a stream of a plurality of individually sealed finished packages.

[0011] Known end seal stages for known packaging machines include the following types: * a rotating shaft end seal machine which has a set of rotating crimp jaws; * a "box motion" end seal machine, having crimp jaws which follow a substantially rectangular or box shaped path with one side of the path following the conveyor; * a reciprocating / rocking movement end seal machine which has a rotary head mounting the crimp heads, and where backwards and forwards in order to extend the contact time with the web of packaging material; * a "D Cam" end seal stage in which a set of crimp heads follow a substantially "D" shaped path with a flat portion of the D shaped path following the product carrying conveyor; * a finger type end seal stage, for example as found on a rotary turret machine, where a set of end crimp heads are mounted on a set of fingers which lower down onto the continuous web of packaging material, where the fingers move along at the same speed as the moving web; * a D motion mechanism where a D motion is created from a circular path mechanism, by springing the jaws together which flattens the profile during the sealing part of the cycle; * tandem head systems; [0012] In each machine type, prior to entering the end seal stage, a stream of products to be packaged are enclosed in a sheet of packaging material, with the longitudinal seal being continuously created, sealing the longitudinal edges of the web of material to each other as the as the web of material passes through a longitudinal sealing section of the packaging machine. The end seal section is downstream of the longitudinal seal section, and in the end seal section the individual packets are created by sealing the ends of the packets and cutting the continuous web of material in order to form the ends of the packets. Longitudinal seals can include either a bottom longitudinal seam seal or a longitudinal inverted seam seal, or in the case of a vertical operating machine, a lap seal.

[0013] Different known flow wrap machines have different levels of versatility and electronic control. When packaging items using a known flow wrap packaging machine, each type of item to be packaged has its own criteria for packaging, and there are various constraints within which the flow wrap packaging machine must operate to satisfy the criteria for an individual product type.

[0014] Requirements of the package which depend upon its use and application comprise the following non -exhaustive list: * whether or not the package should contain an inert gas, or air; * whether or not there are end tucks at each end of the package; * whether the crimp lines on the end seal should lie transverse to the main length of the package or parallel to the main length of the package; * whether the end seals on the package should be cut with a straight edge or with a crimped triangular edge; * the performance of gas tightness of the end seals, which may depend upon the type of item to be packaged; * the performance of gas tightness of the longitudinal seal.

[0015] Requirements of the flow wrap packaging machine, which depend upon the type of product being packaged, the available packaging material, and the requirements of the user of the packaging machine comprise the following non-exhaustive list: * throughput of packages (packages per minute); * reliability of end seals, including seal integrity; * the time, heat and pressure which the seal requires; * the properties of the wrapping material, including the performance band of sealing off the wrapping material; * seal integrity at steady-state conditions and transient states of speed control due to products supplied to the machine starting and stopping; * reject rate -the number of failed packages per 1,000 packages which is acceptable; * product size and range; * the users preference for wrapping material based on local availability and cost.

[0016] Prior art flow wrap machines are electronically controlled and to ensure that each package is of the correct length for the product item, and that the length of the end seals and the sealing position of the end seals are in the correct position relative to the end seal, various parameters can be electronically set.

[0017] Referring to Figure 4 herein there is illustrated schematically a selection of known variable settings for a prior art flow wrap machine of the rotating end seal head type, which can be set electronically using the machines control system. The variable parameters for pack dimensions include: * Pack paper length X -being the overall length of the finished package; * product collation length Y -being the overall length of the product within the package; * product collation position -being the offset of the product from the centre of the package, which determines the position of the product within the package; * product width -being the width of the product; * registration position.

[0018] In addition, in a known flow wrap packaging machine, variable setup and offset parameters of the end crimps can be entered into the machine, said variable parameters comprising: * A number of jaws per shaft, in the case of a rotating end crimp; * an end crimp natural length * an end crimp home offset actual position * an end crimp home offset home sensor offset [0019] In a known flow wrap machine having a rotating end crimp head, parameters such as the end crimp velocity profile, being the velocity of the end crimp over time may be displayed on the machine user interface.

[0020] Constraints which limit the packing rate (number of packets per minute) flowing through the flow wrap machine include the time taken to create the end seal on each packet. The cycle time is the time taken to seal and deliver one product at a particular number of packs per minute, and the sealing time is a portion of the cycle time. This depends upon the type of material which is being used for the packaging sheet material, the pressure which is applied to the packaging sheet material, the temperature which is applied to the packaging sheet material, and the length of time over which the pressure and temperature are applied. In order to achieve high throughput, the available time over which pressure can be applied becomes shorter as the packet line speed increases. The type of material used itself applies constraints to the heat and pressure which can be applied. Some types of sheet material will bond to themselves to form an end seal using pressure only at room temperature. On the other hand, some types of sheet material require an elevated temperature as well as the application of pressure in order to bond to themselves and form a sufficiently robust end seal.

[0021] Each end seal is produced by pressing together the tubular web of sheet material between two end seal heads. The crimp heads can be patterned, each crimp head having a pattern of embossed surface complimentary to an embossed pattern on the other opposite crimp head, or in some cases one of the crimp heads may be in embossed or have a three-dimensional relief, whereas the other opposite head may have a flat surface. In some cases the opposite head may not need a three dimensional relief, but will still require an embossed pattern.

[0022] Similarly, either one or both crimp heads may be electrically heated, and/or temperature controlled, or both crimp heads may have no additional heating or temperature control, depending upon the application and packaging material type.

[0023] There is a problem with known sealing stages of flow wrap machines that in order to achieve increased throughput, the dwell time, being the time over which the crimp heads are in contact with the web of material reduces as line speed increases, but in order to get the packing material to bond to itself quickly the temperature and/or pressure needs to be increased.

[0024] There are upper limits to how much heat and pressure a particular type of packaging material can withstand before the packaging material melts through at the ends of the package.

[0025] Further, the crimp heads have thermal mass. On every revolution of a crimp head, the crimp head loses heat to the end seals of the packages and that heat needs to be reintroduced into the crimp head during the remaining travel path of the crimp head where the crimp head is not in contact with the packet end seal.

As the line speed increases, it becomes more difficult to input enough heat into the crimp heads to achieve the desired temperature, and needed to seal the ends of the packet which is not imparted as heat from the crimp head cannot necessarily be made up for from an increase in pressure between the crimp heads.

[0026] Specific embodiments presented herein aim to increase the portion of cycle time which a sealing crimp head has in contact with a web of packaging material, for a particular line speed of packaging material whilst minimising the accelerations and velocities of the crimp head during the remaining return time during which the crimp head is not in contact with the packaging material.

[0027] Specific embodiments presented herein aim to reduce the pressure required for creating a reliable packet seal by improved contact time and improved heat transfer of the sealing heads of a packaging machine to the packaging material.

[0028] Specific embodiments presented herein aim to increase the time period over which the sealing heads can be heated up, when not in contact with a web of packaging material, for a given line speed of the web of packaging material.

[0029] Specific embodiments presented herein aim to reduce the pressure during transit states to reduce damage packs (start-stop and product supply rate variance).

Summary of the Invention

[0030] Objects are set out above are achieved in various embodiments according to the invention by providing an end sealing stage comprising first and second carousels, each carousel carrying a plurality of end sealing heads each sealing heads being mounted on a carriage. Two opposing carousels of sealing heads provide pairs of sealing heads which crimp a material web therebetween to create an end seal, and to cut the web of material to separate consecutive packages.

[0031] Each carriage follows a non -circular path having a substantially flat portion, where two opposing carriages, one from each of said first and second carousels travel in a same direction and facing each other along a substantially straight path, having said web of packaging material therebetween. At the end of the flat path portion, each carriage follows a return path in the form of a loop which returns the carriage to the start of the flat path portion. During the flat path portion, the sealing profiles are parallel to each other giving greater contact surface with the web material compared to a rotary head.

[0032] For each carousel, the carriages are driven around the path loop corresponding to that carousel by a central driveshaft which has its main axial length direction perpendicular to a plane which contains a track which defines said path. The drive shaft rotates a cam sleeve which pushes the cam follower in a rotational orbit following a noncircular path defined by a track plate, said noncircular path having a substantially flat portion and a looped portion joining first and second ends of said substantially flat portion.

[0033] Whilst the rotational speed of the central driveshaft of each carousel will change in velocity to keep the carousel substantially constant so that during the straight line portion of the path the carriages move in a straight line at a speed which matches the speed of the packaging material on which a plurality of items to be packaged are carried, for the remaining part of the path, the orbital speed of the cam follower around the track will have a motion following a cam profile which will be calculated to match the start and end speed conditions at the start and end of the straight line portion of the path, to give a smooth transition between the orbital part of the path and the straight line portion of the path in the time available.

[0034] Whilst the rotational speed of the central driveshaft of each carousel may be kept substantially constant so that during the straight line portion of the path the carriages move in a straight line at a speed which matches the speed of the packaging material on which a plurality of items to be packaged are carried, for the remaining part of the path, although the angular speed of the cam follower may remain constant, an orbital speed of the cam follower around the track may vary depending on which part of the track the cam follower is travelling.

[0035] In various embodiments, the sealing apparatus comprises a non-circular track (D-shaped track) in which each of the carriages, each of which holds a crimp head are independently driven. The crimp heads are on the carriages, and the carriages are in pairs, one on each side of the product line. Each carriage on one side of the product line is paired with a corresponding carriage on the opposite side of the product line so as to move in synchronisation so the two carriages travel along the flat part of the D track in concert, with the web of material there -between [0036] Each pair of carriages is independently driven, so that at any one time the pairs of carriages move around the non-circular D shaped track independently of each other.

[0037] According to the first aspect of the present invention there is provided an end sealing apparatus for a flow wrap packaging machine, said end sealing stage comprising: a cam track; a plurality of carriages arranged to follow said cam track; and a plurality of drive means for driving said plurality of carriages; wherein each said carriage is independently driven by a separate said drive means.

[0038] Preferably each said carriage is capable of being driven at a variable speed along a path of said cam track independently of one or more other said carriages.

[0039] Preferably said cam track follows a closed loop path.

[0040] Preferably wherein said cam track comprises: a substantially straight portion along which said carriages follow a substantially straight path, said straight portion having a first end and a second end; and a curved portion along which said cam followers follow a return loop path between a first end of said straight portion and a second end of said straight portion.

[0041] Preferably the end sealing apparatus comprises a second plurality of carriages following a second cam track; said first and second cam tracks being spaced apart from each other and lying parallel to each other such that said first plurality of carriages rotate around said first cam track and said second plurality of carriages rotate around said second cam track; wherein each said carriage of said first cam track is paired with a corresponding respective said carriage of said second cam track; and each pair of carriages is driven by a corresponding respective drive train, so that a motion of a first carriage of a said pair is synchronised with a motion of a second carriage of said pair.

[0042] Preferably the end sealing apparatus comprises control means which independently controls each said pair of carriages, so that each carriage pair can move around their respective tracks at a speed which is different to each other pair of carriages.

[0043] Preferably the end sealing apparatus comprises a set of mechanisms which synchronises a carriage of said first plurality of carriages with a carriage of said second plurality of carriages to create a synchronised pair of carriages, wherein the motion of one carriage within said pair is synchronised with motion of the other carriage of said pair.

[0044] Preferably a said carriage comprises: a main body; a first cam track follower located at a first end of said main body; and a second cam track follower located at a second end of said main body.

[0045] Preferably the end sealing apparatus comprises one or a plurality of cam track plates, each said cam track plate comprising: a plate member, said plate member having an aperture there -through; an outer track wall; and an inner track wall, wherein said outer and inner track walls define a path there between.

[0046] Each said drive means preferably comprises: a corresponding respective electric motor; and a corresponding respective drive transmission shaft.

[0047] Preferably, a plurality of said drive transmission shafts are arranged coaxially along a single axis of rotation, each said drive transmission shaft having 20 an angular range of movement over which it can move independently of each other said drive transmission shaft.

[0048] Preferably each said carriage comprises a first track follower on a first side of said carriage, arranged to follow around a first track on a first track plate; and a second track follower on a second side of said carriage, arranged to follow around a second track on a second track plate.

[0049] Preferably a said track is defined by a track plate, said track plate comprising an outer track wall and an inner track wall, said outer and inner track walls defining a path there between.

[0050] According to a second aspect of the invention is provided an end sealing apparatus for a flow wrap packaging machine, said end sealing stage comprising: a first carousel having a first set of carriages; a second carousel having a second set of carriages; a first drive means for driving a first one of said first set of carriages in synchronisation with a first one of said second set of carriages; a second drive means for driving a second one of said first set of carriages in synchronisation with a second one of said second set of carriages; and wherein each of said first and second drive means are independently controllable.

[0051] Preferably said first drive means comprises a first motor; and said second drive means comprises a second motor.

[0052] Preferably there is provided a third drive means for driving a third one of said first set of carriages in synchronisation with a third one of said second set of carriages, and preferably said third drive means comprises a third electric motor.

[0053] In other embodiments, the drive means may comprise electromagnetic drives; magnets and drive rings; and/or electrical rotary or linear drives. In the case of linear drives, the drive means may comprise multiple movers/sealing jaw heads.

[0054] Preferably the end sealing apparatus further comprises: a first synchronisation means for synchronising a motion of said first one of said first set of sealing heads with a motion of a first one of said second set of sealing heads; and a second synchronisation means for synchronising a motion of said second one of said first set of sealing heads with a motion of a second one of said second set of sealing heads.

[0055] Where each carousel comprises a third sealing head, preferably there is provided a third synchronisation means for synchronising motion of said third one of said first set of sealing heads with a motion of a third one of said second set of sealing heads.

[0056] In the embodiments described above, a first carousel may comprise: a first track plate and a second track plate; a first plurality of carriages each arranged to follow one or more tracks defined by said first and second track plates; wherein said first and second track plates each describe a path having a first substantially flat portion and a second looped portion, said looped portion connecting with said substantially flat portion to create a closed circuit path; each said carriage of said first plurality of carriages being rotationally driven by at least one corresponding respective cam member.

[0057] In the embodiments described above, a second carousel may cornprise: a third track plate and a fourth track plate; a second plurality of carriages each arranged to follow one or more tracks defined by said third and fourth track plates; wherein said third and fourth track plates each describe a path having a first substantially flat portion and a second looped portion, said looped portion connecting with said substantially flat portion to create a closed circuit path; each said carriage of said second plurality of carriages being rotationally driven by at least one corresponding respective cam member.

[0058] In various embodiments according to the invention, there is provided a pair of opposing carousels each having a corresponding respective main central axle, said pair of central axles being parallel to each other a first plurality of carriages arranged to orbit around said axle of said first carousel, a second plurality of carriages arranged to orbit around said axle of said second carousel; a first plurality of sealing heads mounted to said first plurality of carriages; a second plurality of sealing heads mounted to said second plurality of carriages; said first plurality of carriages being synchronised with said second plurality of carriages such that each said first sealing head travels opposite to a corresponding respective said second sealing head for at least part of its motion over a substantially straight path; wherein each carriage of said first plurality of carriages is paired with a corresponding respective carriage of said second plurality carriages so that the motion of each carriage in a said pair mirrors the motion of the other carriage of said pair; each said pair of carriages being driven by a separate drive train.

[0059] Preferably each of the drive trains are independently controllable so that each pair of carriages are controllable independently of the motion of the other said pairs of carriages.

1 0 [0060] Preferably the carousels are adjustable on an external frame having an adjustment mechanism which allows the upper carousel to be adjusted towards or away from the lower carousel either manually or via an electronic control mechanism so as to change the distance between the upper and lower carousels, which gives the ability to change the pressures on the opposing crimp heads either during an initial setup, or on-the-fly during a production run of packages.

[0061] The specific embodiments disclosed may have the following advantages.

[0062] By providing a set of carriages which follow a defined track, there can be achieved a straight line linear motion of a pair of crimp heads or end seal heads which matches a speed of a packaging material carrying a plurality of items to be packaged, but without the need for a fully reciprocating gantry. The reciprocating mass of the components in the embodiments herein, can be made lower than the reciprocating mass of a prior art end seal stage.

[0063] The embodiments may allow flexibility to run independent speed profiles, providing a large size range within the same mechanical constraints (compared to a single drive cam track which has significant restrictions for size changes), without any additional stress or duress on the sealing head mechanisms.

[0064] The above aspects encompass both horizontal form fill seal (HFFS) and vertical form fill and seal (VFFS) flow wrap packaging machines, capable of creating three or four sided seals, top seals and /or multi lane flow wrap packaging machines. The aspects described herein can be applied to any type of flow wrap machine which performs end sealing.

[0055] Other aspects are as set out in the claims herein, the full content of which is incorporated into this summary of invention by reference.

Brief Description of the Drawings

[0066] For a better understanding of the invention and to show how the same may be carried into effect, there will now be described by way of example only, specific embodiments, methods and processes according to the present invention with reference to the accompanying drawings in which: Figure 1 shows schematically a known product package created on a known flow wrap packaging machine; Figure 2 shows schematically a second known product package created on 20 a known flow wrap packaging machine; Figure 3 shows schematically the underside of a third known product package created on a known flow wrap packaging machine; Figure 4 shows schematically in cut away view a known product package, illustrating dimensional parameters of the known package which can be varied on unknown electronically controllable packaging machine; Figure 5 shows schematically in perspective view a novel flow wrap packaging machine according to a specific embodiment of the present invention; Figure 6 shows schematically the end seal stage in perspective view from above and a first direction; Figure 7 shows schematically the end seal stage in perspective view from above and a second direction; Figure 8 shows schematically the end seal stage in perspective view from above and a third direction; Figure 9 shows schematically the end seal stage from a second side; Figure 10 shows schematically the end seal stage from a first end; Figure 11 shows the end seal stage from above; Figure 12 shows schematically in perspective view a track plate containing a track, and a track follower which travels around the track; Figure 13 shows schematically in view from one side details of a cam track follower; Figure 14 shows schematically in view from the rear and a second side a subassembly of the sealing stage showing three separate drive trains for controlling three separate pairs of carriages; Figure 15 shows schematically in view from the rear and the second side a subassembly showing a first drivetrain to a first pair of carriages of the sealing stage; Figure 16 shows schematically in view from the rear and the first side second a subassembly showing a second drivetrain to a second pair of carriages of the sealing stage; Figure 17 shows schematically from the rear and the first side a subassembly showing a third drivetrain to a third pair of carriages of the sealing stage; Figure 18 shows schematically the end sealing apparatus at a first stage of travel along a substantially straight portion of a motion of a pair of opposing sealing heads; Figure 19 shows schematically the end sealing apparatus at a second stage of travel along a substantially straight portion of a motion of a pair of opposing sealing heads; Figure 20 shows schematically the end sealing apparatus at a third stage of travel along a substantially straight portion of a motion of a pair of opposing sealing heads; and Figure 21 illustrates schematically in perspective view a variation of a track plate containing a track, and a track follower which travels around the track, where the track follower has a pair of toothed wheels which engage with an inwardly facing toothed track of the track plate.

Detailed Description of the Embodiments

[0067] There will now be described by way of example a specific mode contemplated by the inventors. In the following description numerous specific details are set forth in order to provide a thorough understanding. It will be apparent however, to one skilled in the art, that the present invention may be practiced without limitation to these specific details. In other instances, well known methods and structures have not been described in detail so as not to unnecessarily obscure the description.

[0068] In this specification the term sealing head is used interchangeably with the term crimp head to mean the same thing. A crimp head or sealing head is known in the art of flow wrap packaging machines as a component which presses against a web of material to create a seal, typically by pressing one portion of the web of material against another portion, under pressure and with or without additional higher temperature. A crimp head or sealing head may also comprise a knife which operates to separate individual packets or packages from a continuous web of sheet material.

Overview of packaging machine [0069] Referring to Figure 5 herein there is illustrated schematically in perspective view a flow wrap packaging machine suitable for a range of wrapping applications including flow wrapping of products such as bakery products, biscuits, chilled and frozen foods, chocolate and confectionery items, consumer or healthcare products and dry goods.

[0070] The flow wrap packaging machine 500 comprises a feed conveyor 501 for transporting a stream of items to be packaged; a web roller stage 502 for holding one or a plurality of rolls of sheet packaging material; a wrapping stage 503 for wrapping the individual product items in the web of sheet material, the wrapping stage comprising a folding stage for folding over a continuous web of sheet packaging material around items to be packaged, an edge sealing stage for sealing longitudinal edges of a said sheet of packaging material, and an end sealing stage for sealing the ends of individual packages and separating individual packages from each other; a control unit 504 for controlling operation of the feed conveyor, wrapping stage, and end seal stage; and a user interface 505 for setting and altering variable parameters according to package size, product type, and type of wrapping material.

[0071] The web roller stage 502 comprises one or a plurality of rotatable axles or rollers onto which one or a plurality of rolls of packaging sheet material are mounted; and a feed mechanism through which the continuous web of packaging material is fed and transported adjacent and along the feed conveyor.

The feed mechanism and roll mounts are controlled by one or a plurality of servo motors and the control stage.

[0072] The wrapping stage 503 takes as its in feed the continuous stream of individual items to be packaged and the continuously moving web of sheet material. At the input of the wrapping stage, the web of sheet material is a single substantially flat sheet continuously moving at the same speed as the individual items to be packaged on the feed conveyor. The folding stage comprises a plurality of sheet material guides and rollers which fold the sheet material over as it is moving, so that the sheet is folded into a first portion (lower portion) and a second portion (upper portion), the first and second portions being connected by an edge portion on one side and being open on the other side. The plurality of items to be packaged are partially enclosed between the first and second portions as the sheet of material moves along the packaging machine, and the web of packaging material and stream of product items are fed into the edge sealing stage where the open side of the web of packaging material is continuously sealed along the length of the sheet of packaging material.

[0073] The end seal stage comprises a plurality of opposing pairs of crimping or sealing heads which follow the continuously moving web of sheet material over a distance as it moves through the end seal stage, crimping the sheet material between said pairs of crimp heads at positions between the individual items contained within the sheet so that there are created a plurality of individual packages each said package having first and second ends which are sealed by the crimping heads. At least one of each pair of crimping heads comprises a knife blade which cuts the web of material thereby dividing the web of sheet material into individual packets within which the packaged items are contained. The crimp heads may operate either by electrical heating, having internally and electrical resistance wire, or in other variations may be heated by electric induction. Alternatively, the crimp heads may have an ultrasonic generator to seal the packaging material using ultrasonic energy.

[0074] Optionally there may be provided a mechanical servo driven end tucking stage which tucks in the sides of the packaging material near to the end of the package so that the material folds over on itself, the ends of the tucked in sides being sealed along with the upper and lower parts of the web of packaging material to provide an end -tucked package as shown in Figure 2 herein. As a further option, instead of a mechanical servo -driven end tuck stage, the end tucks may be formed by air pressure released from a pair of nozzles, one on either side of the web of packaging material.

[0075] The control unit 504 comprises an electrical power supply; a motion controller for controlling all functions of the packaging machine; a plurality of electric servo motor controllers for controlling a plurality of servo motors which drive the feed conveyor, roller stage, fold-over stage, edge seal stage, and the end sealing stage.

[0076] The user interface 505 comprises a touch-sensitive display screen which displays individual parameters of the packaging machine which can be set and varied by means of user touch inputs on the touch sensitive user interface screen and which provides a visual display of operation of the machine and its individual stages.

[0077] The packaging machine is provided with a plurality of adjustable floor mounts 506 having adjustable legs or feet to accommodate undulations in a factory floor surface and to enable the packaging machine to be installed stably and level.

End sealing stage layout and construction [0078] Referring to Figures 6 to 11 herein, there is illustrated schematically in various views the end seal stage of the novel packaging machine described herein.

[0079] The end sealing stage comprises a first carousel 601 which carries a first plurality of crimp heads 602; a second carousel 603 which carries a second plurality of crimp heads; a chassis or frame comprising first side frame 604, and second side frame 605, said first and second side frames being spaced apart from each other and each having their respective lower ends being mounted on a common lower frame portion, so that the first and second side frames are rigidly held apart from each other, and form a rigid outer frame for holding the first and second carousels adjacent each other.

[0080] In the layout shown, the end sealing stage is arranged for sealing the ends of a flow of product items which are transported in a substantially horizontal flow direction, and the first carousel 601 is arranged above the second carousel 603 with the product stream flowing horizontally between the upper and lower carousels. However in the general case, the orientation of the end seal stage is not restricted to sealing a horizontally flowing stream of packages and other configurations are possible, such as a vertical stream of packages, in which case the first and second carousels would lie opposite each other and side-byside, with a vertical stream of packages passing between the first and second carousels. It will be understood in the following description that where an upper and a lower carousel are referred to, the arrangement of the first and second carousels may be orientated in any orientation in three-dimensional space.

[0081] Each carousel comprises a pair of opposing end plates or track plates, 721, 722, and 722, 723 each of which has a loop or ring track; and a set of three separate carriages, each carriage carrying a corresponding respective sealing head. A first end plate 721 of the first carousel is attached to inner first frame plate 713; a second end plate 722 of the first carousel is attached to inner second frame plate 714, a first end plate 723 of the second carousel is attached to inner first frame plate 713; and a second end plate 724 of the second carousel is attached to inner second frame plate 714, with the result that both carousels are located between the inner first and second frame plates, each carousel having its first end plate attached to one side of the assembly and each carousel having its second end plate attached to an opposite, second side of the assembly.

[0082] Optionally, the first and second end plates or track plates 721, 722 may be mounted on sliding mounts to the inner first frame plate 713 and in a second frame plate 714 to allow for distance adjustment of the whole upper carousel relative to the lower carousel. The adjustment can be a manual adjustment whereby the upper carousel is slid on the sliding mounts and secured by clamps or bolts in a pre-production run setup procedure. Alternatively, the first and second end plates can be mounted upon motorised sliding mounts which slide towards or away from the second carousel under automated control, in which case the distance between the upper and lower carousels may be varied in real-time during operation of the packaging machine.

[0083] Similarly, sliding mounts may be provided to the lower carousel as described with respect to the upper carousel, so that the overall spacing of the lower carousel relative to the upper carousel can be varied.

[0084] The carriages travel around the tracks provided in the end plates in a loop motion, the first and second carousels rotating in opposite rotational senses to each other. That is, if the carriages of the first carousel rotate clockwise around the tracks of the first carousel, then the carriages of the second carousel rotate anticlockwise around the tracks of the second carousel, and vice versa if the carriages of the first carousel rotate anticlockwise around the tracks of the first carousel, then the carriages of the second carousel rotate anti-clockwise around the tracks of the second carousel.

[0085] The carriages are arranged in pairs so that a first carriage of the first carousel is synchronised with and paired with a first carriage of the second carousel and both carriages of the pair are driven by a common first drive motor 700. A second carriage of the first carousel is synchronised with and paired with a second carriage of the second carousel and the second carriages share a common second drive motor 701. A third carriage of the first carousel is synchronised with and is paired with a third carriage of the second carousel and the third carriages share a common third drive motor 702. Each of the drive motors are independently controlled so that the positions of each pair of carriages along their respective tracks can be varied independently of the position of each other pair of carriages, provided that the carriages always appear in the same order around the direction of the loop of the tracks.

[0086] The rotating carriages may include a jaw relief or "soft jaw" feature, which prevents misplaced products from jamming in the end seal jaws. The drive motor torque is constantly monitored and any increase above normal running evet causes the jaws and carriages to reverse direction. This allows the misplaced product to pass through the jaws and produces a long pack that is rejected from the machine discharge. When the obstruction is dear of the jaws the machine automatically resumes normal operation.

Frame construction [0087] First side frame 604 comprises an inner first side frame plate 713; and outer first side frame plate 711, spaced apart from and parallel to the inner first side frame plate, there being a gap between the inner first side frame plate and the outer first side frame plate. The inner and outer first side frame plates are positioned substantially parallel to each other and spaced apart from each other by a plurality of cross beams 712.

[0088] Second side frame plate 605 comprises an inner second side frame plate 714; and an outer second side frame plate 716, wherein the inner and outer side frame plates are spaced apart from each other and held substantially parallel to each other by a plurality of second cross beams 715.

[0089] The first and second carousels are located between the first and second side frames 604, 605. The first side frame 604 mounts a third set of synchronising gear wheels for the third pair of carriages and mounts first, second and third drive motors for driving the respective first, second and third pairs of carriages.

[0090] The second side frame 605 mounts the synchronising gear wheels for the first and second pairs of carriages.

Track plates and track shape [0091] Referring to Figure 12 herein, there is illustrated schematically in perspective view one end plate or track plate 1300 and one track follower at one end of a carriage.

[0092] The track plate comprises a rigid metal plate 1300, into which is formed a track 1301. The cam track comprises an outer cam track wall 1302 which extends in a direction perpendicular to a main central plane of the metal plate; an inner cam track wall 1303 which extends in a direction perpendicular to the main central plane of the metal plate, wherein the inner cam track wall lies inside and substantially parallel to the outer cam track wall, there being a substantially constant spacing between the inner and outer cam track walls which accommodates passage of a corresponding respective roller or bearing.on one end of each carriage.

[0093] Outer cam track wall 1302 comprises a wall of metal of substantially constant thickness, which extends in a direction parallel to a main central axis of the carousel. The outer cam track wall comprises a first wall surface facing inwardly towards a main central axis of the carousel, and having a smooth walled track formed thereon; a second wall surface facing outwardly away from the main central axis of the carousel; the first and second wall surfaces being separated by the thickness of metal which is substantially constant all the way around the outer cam track.

[0094] Inner cam track wall 1303 comprises a wall of metal which is a substantially constant thickness and which extends in a direction parallel to the main central axle of the carousel, said inner cam track wall 1303 comprises a first wall surface which faces inwardly towards the centre of the cam track plate and a second wall surface which faces outwardly from the centre of the cam track plate, said first and second wall surfaces being separated by the thickness of the material of the inner cam track wall. The inner cam track wall comprises a first wall portion 1305 which is substantially straight and/or may be slightly rounded with a relatively large radius of curvature relative to the remainder of the inner cam track wall; at a first end of the first wall portion a first relatively lower radius curved portion 1306; at a second end of the first wall portion, there is a second relatively lower radius curved wall portion 1307; said first and second relatively lower radius wall portions 1306, 1307 being connected by a third wall portion 1308 which forms a continuous loop with the first and second relatively lower radius wall portions, the overall effect being that the shape of the inner cam track wall as viewed in a direction parallel to a main central axis of the carousel, and perpendicular to the main plane of the cam plate is that the cam track follows a substantially "D" shaped path.

[0095] Overall, the shape of the substantially "D" shaped path resembles a circular tube which has had one side squashed or deformed against a flat surface. The track has a substantially straight portion which allows the carriages to travel in a substantially straight line over a short distance, so that the carriages of a pair of carriages can face each other over that short distance, the crimp heads of each carriage facing each other with a web of packaging material therebetween.

[0096] The shape of the outer cam track wall 1302 follows the shape of the inner cam track wall, being spaced apart from the inner cam track wall by a fixed distance as measured in a direction perpendicular to the tangent of the curved outer wall surface of the inner cam track wall 1303.

[0097] The track plate may be manufactured by forming an initial casting of the cam plate in the approximate finished shape of the cam plate including the inner and outer cam track walls and finished by CNC machining of the cam track walls. Alternatively, the cam plate may be machined from a solid block of steel. Optionally, the cam may be split into two halves for quick removal.

Cam track followers [0098] Referring to Figures 12 and 13 herein, an individual cam track follower comprises a main body comprising an inner end plate 1350; an outer end plate 1351 and a laterally extending body portion 1352 between the inner end plate and the outer plate. The outer end plate is provided with a plurality of through-holes for mounting first and second outer rollers 1353, 1354; and inner roller 1355.

[0099] First and second outer rollers 1353, 1354 bear against the smooth outer facing surface of the cam track outer wall 1302, whilst inner roller 1355 bears against the inwardly facing surface of cam track inner wall 1303, as the cam track follower follows around the track defined by the inner and outer track walls..

[0100] Wien the cam track follower is passing along the substantially flat track portion, the carriage is orientated so that the outwardly facing crimp head follows a substantially straight line path corresponding to the distance of the flat or straight portion of the D Cam track.

[0101] In other embodiments of cam track followers which are designed to follow a cam track plate having inner and outer walls each wall having a corresponding inner and outer smooth curved surface and an additional toothed curve. A further pair of toothed gears with connecting driveshaft keeps carriage parallel between the two cams.

Carousel construction [0102] Referring to Figures 6 to 17 herein, first or upper carousel 601 comprises a first pair of track plates 721, 722 facing each other and spaced apart from each other; a rotatable first drive shaft 1500 having first and second ends; and a first plurality of carriages which orbit around first drive shaft 1500.

[0103] The carriages are arranged in pairs so that a first carriage of the upper carousel is synchronised with a first carriage of the lower carousel, a second carriage of the first carousel is synchronised in its movement with a second carriage of the lower carousel and the third carriage of the upper carousel is synchronised in its movement with a third carriage of the lower carousel.

[0104] The first or upper carousel therefore comprises three carriages, each of which is paired with a corresponding respective carriage on the lower carousel. Each pair of carriages has its own drive motor and drive train which is independently controllable. A first drivetrain drives a first upper carriage on the upper carousel and a first lower carriage on the lower carousel. Similarly, a second drivetrain drives a second upper carriage on the upper carousel and a second lower carriage on the second carousel and a third drivetrain drives a third upper carriage on the upper carousel and a third lower carriage on the lower carousel.

[0105] Taking as an example the first upper carriage on the upper carousel, a second end of first drive shaft 1500 is attached to a synchronising gear wheel 1505; a second end of first driveshaft 1500 is attached to a first toothed drive wheel 1501 which is driven by first carousel drive motor 700 via a toothed belt 1503. A main carriage beam 1520 of first carriage 1521 of the first carousel is attached to the first drive shaft 1500 by a pair of rotatable collars 1509, 1510 which are keyed to the first drive shaft 1500 to rotate with the first drive shaft, so that the first carriage is rotatable as the first driveshaft rotates.

[0106] The main beam of the first carriage is attached to the collars 1509, 1510 by a pair of corresponding respective linearly slidable telescopic linkage which allows the beam of the first carriage to extend and retract in a direction radially of a main central axis of the first drive shaft 1500, so that as the first carriage1502 orbits the main central axis of the first drive shaft 1500 in a non-circular orbit around the paths of the tracks, the main length axis of the central beam of the first carriage remains parallel to the main central axis of first driveshaft 1500 whilst rotating with the first drive shaft 1500.

[0107] Considering the carriages of both the upper and lower carousels, at each end of the first main beam of each carriage, there is provided a corresponding respective cam track follower 1530, 1531 an example of which is shown in figure 13 herein, each cam track follower being driven rotationally by corresponding respective drive sleeve or drive collar.

[0108] Second or lower carousel 603 comprises a second pair of track plates 723, 724 facing each other and spaced apart from each other; a rotatable second drive shaft 1502 having first and second ends; and a second plurality of carriages which orbit around the second drive shaft 1502.

[0109] A main beam 1515 of a first carriage 1508 of the second set of carriages on the second (lower) carousel is attached to the second drive shaft 1502 by a pair of drive collars 1511, 1512 which are keyed on to the second drive shaft, so that the first carriage is rotatable with the second driveshaft 1502. The main beam of the first lower carriage is attached to the drive collars 1511, 1512 by a corresponding respective pair of linearly slidable telescopic linkages which allows the beam of the first lower carriage to extend and retract in a direction radially of a main central axis of the second drive shaft 1502, so that as the first lower carriage orbits the main central axis of the second drive shaft 1502 in a non-circular orbit, the main length axis of the central beam of the first lower carriage remains parallel to the main central axis of the second driveshaft 1502.

[0110] At each end of the main beam of the first lower carriage there is provided a corresponding respective cam follower 1519, 1520. Each cam follower is driven rotationally by corresponding respective collar or sleeve 1511, 1512.

[0111] First drive shaft 1500 of the first carousel lies parallel to and spaced apart from second drive shaft 1502 of the second carousel. In Figure 15, only one carriage of the first carousel is shown and only one carriage 1508 of the second carousel is shown, to aid clarity of explanation, but it will be understood from the description and other drawings that each carousel comprises a plurality of such carriages.

Carousel synchronization & drive to the carriages [0112] Referring to Figure 14 herein, there is illustrated schematically a sub assembly comprising a first, second and third drive train for driving respectively a first, second and third pair of carriages. Each drivetrain drives one carriage from the first carousel and one carriage from the second carousel, wherein each of the drive trains has a corresponding respective electric motor, each motor and therefore each drivetrain being independently controllable by the control system. Three separate drive trains control three separate pairs of carriages.

[0113] Figure 15 shows schematically in view from the rear and the second side a subassembly showing a first drive train to a first pair of carriages of the sealing stage.

[0114] Referring to Figures 14 and 15 herein, first drivetrain comprises first drive motor 700; upper drive shaft 1500 which extends centrally through the first (upper) carousel; second driveshaft 1502 which extends centrally through the second carousel; a toothed drive belt 1503 connecting an axle of the first drive motor 700 to a toothed wheel 1504 attached to a first end of the first driveshaft; a first toothed gear wheel 1505 connected to the second end of the first driveshaft 1500; a second toothed gear wheel 1506 connected to the second end of the second driveshaft 1502, the teeth of the first and second toothed gear wheels engaging each other so that the rotational position of the first driveshaft 1500 of the first carousel is synchronised with the rotational position of the second drive shaft 1502 of the second carousel; first upper carriage 1507 on the first or upper carousel; first lower carriage 1508 on the second or lower carousel; first and second upper drive collars 1509, 1510 to which the first upper carriage 1507 is mounted; and first and second lower drive collars 1511, 1512 to which the first lower carriage 1508 is mounted.

[0115] First upper carriage 1507 is driven rotationally by first and second upper drive collars 1509, 1510 but are radially slidable with respect to the collars through a fork arrangement 1400, 1401 as shown in Figure 13 herein. The first upper carriage 1507 can move radially inwardly or outwardly with respect to the first driveshaft 1500 as the drive shaft rotates, which enables the track followers 1513, 1514 of the first upper carriage to follow a noncircular path, which has a varying radial distance from the main central axis of the first driveshaft 1500 as the track followers follow the D shaped path.

[0116] The first and second drive shafts of the respective first and second carousels are rotationally synchronised by the toothed gear wheels attached to the ends of the first and second drive shafts. First gear wheel 1505 of first driveshaft 1500 meshes with gear wheel 1506 of second driveshaft 1502, so that as the first driveshaft turns in an opposite rotational direction to the second driveshaft. When the first driveshaft turns in a first rotational direction, the second driveshaft turns in a second opposite rotational direction and vice versa, when the first driveshaft turns in the second rotational direction, the second driveshaft turns in the first rotational direction, wherein the rotational angle of the first driveshaft is 1 0 linked to the rotational angle of the second driveshaft by the inter-meshing teeth of the first and second toothed gear wheels 1505, 1506.

[0117] In operation, first motor 700 drives toothed belt 1503 which rotates the end wheel 1504 thereby rotating the upper driveshaft 1500. The upper driveshaft 1500 rotates the first and second upper drive collars 1509, 1510 which in turn rotates the first upper carriage 1507 around the tracks located on the upper track plates 721, 722. First toothed gear wheel 1505 attached to the second end of the first driveshaft 1500 rotates the second toothed gear wheel 1506 attached to the second end of the second driveshaft 1502. First and second lower drive collars 1511, 1512 are driven by the second driveshaft 1502 in an opposite rotational direction to the rotation of the first driveshaft 1500 and push the first lower carriage 1508 around the tracks of the lower track plates 723, 724 with the result that the first upper carriage and first lower carriage rotate around their respective track's paths in synchronisation with each other driven by the first drive motor 700.

[0118] Referring to Figures 14 and 16 herein, there is illustrated schematically components of a second drivetrain for driving a second pair of carriages comprising second upper carriage 1700 and second lower carriage 1701 in synchronisation. The second drivetrain comprises the second drive motor 701; a third driveshaft 1702 driven by the second drive motor 701 via a toothed end wheel 1703 and drive belt 1704, each at a first side of the end seal stage; a third toothed drive wheel 1705 attached to a second end of third driveshaft 1702, and the third toothed drive wheel engaging with a fourth toothed drive wheel 1706 which drives the second lower carriage 1701 of the second or lower carousel; said fourth toothed drive wheel 1706 being rotatable with respect to the second driveshaft 1502; a fifth toothed drive wheel 1707 which rotates around the first driveshaft 1500 and which drives second upper carousel 1700.

[0119] Fourth drive wheel 1706 drives a third lower drive collar 1708 via a tubular circular cylindrical shaft which fits around second driveshaft 1502 and which is rotational with respect to said second driveshaft. The third lower drive collar 1708 drives a fourth lower drive collar 1709 via a linkage arm 1710 which connects said third and fourth lower drive collars.

[0120] Second lower carriage 1701 comprises cam track followers 1711, 1712 at each side of the carriage for following the tracks provided in the lower track plates 723, 724 so that as the fourth drive wheels 1706 rotates, the third and fourth lower collars 1708, 1709 drive the second lower carriage around the lower tracks of the second or lower carousel. Similarly as shown in Figure 13 herein, the second lower carriage is mounted between a pair of fork members 1400, 1401 which drive the second lower carousel rotationally at the same radial angle as the third and fourth lower drive collars 1708, 1709 but which allow the second lower carriage to vary its radial distance with respect to the third and fourth lower collars and with respect to a main central axis of the second shaft 1502, so that the second lower carriage can follow the noncircular path defined by the lower track plates 723, 724.

[0121] Upper second carousel 1700 is driven by the fifth toothed drive wheel 1707 via a tubular circular cylindrical collar or sleeve 1713 which fits over the upper driveshaft 1500 and is independently rotatable with respect to the upper driveshaft 1500. Similarly as described with respect to the third and fourth lower collars, third and fourth upper collars 1713, 1714 are linked together by a linkage arm 1715 which causes the third and fourth upper collars to rotates around the upper shaft 1500 together, driving the second upper carriage 1700 around the upper tracks defined by the upper track plates 721, 722.

[0122] The rotational position of the second upper carriage 1700 is synchronised with the rotational position of the second lower carriage 1701 by the fixed rotational relationship between the fourth toothed drive wheel 1706 and the fifth toothed drive wheel 1707, each of which are ultimately driven by the same second drive motor 701.

[0123] The radial position of the second upper carriage with respect to the first driveshaft 1500 and the upper third and fourth drive collars 1713, 1714 is variable depending upon the position around the track or path which the carriage occupies. Similarly, the radial position of the second lower carriage 1701 with respect to a main central axis of the second or lower driveshaft 1502 depends upon the position of the second lower carriage around the lower track.

[0124] The second drive motor 701 is independently controlled with respect to the first and third drive motors, which means that the rotational position of the second upper and lower carriages is independently controllable with respect to the rotational positions of the first and third sets of carriages.

[0125] Referring to Figures 14 and 17 herein, there is illustrated schematically components of a third drivetrain for driving third upper carriage 1800 and third lower carriage 1801.

[0126] The third drive train comprises third drive motor 702 which drives a sixth drive wheel 1803, said sixth drive wheel being mounted on and rotatable with respect to the third driveshaft 1702; a toothed drive belt 1804 for driving the sixth drive wheel from an output shaft of third drive motor 702; a seventh geared drive wheel 1805 mounted on second shaft 1502 and being rotatable with respect to second driveshaft 1502; an eighth geared drive wheel 1806, gear teeth of the seventh and eighth drive wheels 1805, 1806 being in meshed engagement with each other so that the rotational positions of the seventh and eighth drive wheels are synchronised with each other; the seventh and eighth drive wheels being rotatable in opposite rotational directions to each other; lower fifth and sixth drive collars 1807, 1808 for urging the third lower carriage around the lower drive track; and upper fifth and sixth drive collars 1809, 1810 for urging the upper third carriage around the upper drive track.

[0127] The fourth lower collar 1808 is connected to the third lower drive collar 1807 by a linkage arm 1811 which ensures that the sixth lower drive collar rotates around lower driveshaft 1502 with the same angular rotational position as the fifth lower drive collar 1807. Similarly, there is provided a linkage arm 1812 between the fifth upper drive collar 1809 to the sixth upper drive collar 1810 to ensure that those two drive collars rotate at a same rotational angle as each other around the upper driveshaft 1500.

[0128] Similarly as with the first and second sets of carriages, the third carriages are connected to their respective drive collars via a fork arrangement which enables the carriages to move in and out radially towards the main central axis of the upper or lower driveshaft as appropriate whilst being driven rotationally around the corresponding upper or lower tracks so that the third upper carriage and third lower carriage travel around their respective upper lower drive tracks in synchronized movement with each other to meet opposite each other and travel together along the substantially straight part of the tracks as shown in Figure 18 opposite each other.

[0129] The fifth and sixth upper drive collars 1809, 1810 are rotatable with respect to the first driveshaft 1500. Similarly, the lower fifth and sixth drive collars 1807, 1808 are rotatable with respect to the second or lower driveshaft 1502. The fifth and sixth drive collars are each mounted to their corresponding shaft via a corresponding respective roller bearing.

Carriage construction [0130] Each carriage comprises a main beam having a main length direction which extends in use parallel to a main central axis of the respective driveshaft of the carousel; a first cam follower rigidly attached to a first end of the main beam; a second cam follower rigidly attached at a second end of said main beam; and a packet end sealing head or crimp head for sealing the ends of individual packets which pass between the first and second carousels.

[0131] Referring to Figures 12 and 13 herein, each cam follower comprises an outer plate 1350; an inner plate 1351; and a cross plate 1352 connecting the inner plate and the outer plate. The outer plate has a plurality of apertures which accommodate bolts to connect first and second outer roller bearings 1353; first and second track follower rollers or bearings 1355, 1356; and an inner roller bearing 1357.

[0132] Between the inner plate and the outer plate, and attached to the outer plate, there is provided a circular bearing 1358 which locates between first and second prongs of a fork arrangement mounted to sleeve 1360 which fits around the central driveshaft. The bearing 1358 can slide radially inwardly and outwardly with respect to the drive shaft, towards and away from the central driveshaft between the prongs 1400, 1401 of the fork. As the sleeve or collar 1361 rotates around the central axis of the driveshaft, the cam follower moves radially inwardly and outwardly with respect to the main central axis of the driveshaft as it follows the non-circular path of the track.

Operation [0133] Referring to figures 18 to 20 herein, there is illustrated schematically the formation of one packet end seal as a web of sheet packaging material passes through the end sealing stage.

[0134] In figure 18 herein, a package 1900 which has already had one end sealed by a pair of sealing heads on first carriages 1901, 1902 is travelling through the sealing head between the first and second carousels. A second pair of carriages 1903, 1904 is at the start of the substantially straight portion of the track and begins to crimp the web of packaging material at a position corresponding with the end of the preceding packet 1900, and the start of a new packet 1905.

[0135] In figure 19 herein, the carriages have moved around the first and second carousels a further distance, the upper carousel rotating anticlockwise and the lower carousel rotating clockwise as viewed in figure 19. At the position shown in figure 19, the second pair of carriages 1903, 1904 are approximately midway along the substantially flat portion of the tracks. The web of sheet material is pressed between the sealing heads on the upper and lower second carriages, which forms an end seal on the preceding packet 1900 and an end seal on the next packet 1905.

[0136] In figure 20 herein, the second carriages are reaching the end of a substantially straight part of the tracks and are about to embark on the return loop portion of the tracks, having created an end seal on the preceding packet 1900 and a front end seal on the next packet 1905. The third pair of carriages 1906, 1907 are in a position to commence a run along the substantially straight portion of each of the upper and lower the D cam tracks to form a second end seal on the next packet 1905.

Cam track follower speed [0137] Each cam track follower travels along its respective cam track at a linear speed in the direction of the path of the cam track which can be continuously varied, depending on the position of the cam follower along the length of the closed loop cam track. The speed of the cam follower along a substantially straight part of the cam track path where the sealing head contacts the web of packaging material is controlled by the servo motor driving the pair of carriages so that the linear speed of the pair of carriages corresponds with the line speed of the web of packaging material flowing past the end sealing stage. The rotational speed of the drive train is controlled to provide a constant linear speed of the pair of carriages along the substantially straight part of the track to correspond with the line speed of products. On the return phase of the journey around the cam track from the end of the substantially straight part of the path to the start of the substantially straight part of the path, the cam follower has a different linear speed along the track to return the carriage to the start of the straight run pad of the track.

Alternative embodiment cam track followers [0138] Referring to Figure 21 herein, there is shown a variation on the end plate comprising the track, in which the track is provided with a toothed outer wall, and the end of the carriages provided with a toothed wheel as well as a smooth circular outer faced roller or bearing. A track follower 2100 comprises a main body comprising an inner end plate 2101; an outer end plate 2102 and a laterally extending body portion 2103 between the inner end plate and the outer plate. The outer end plate is provided with a plurality of through-holes for mounting first and 1 0 second outer rollers 2104, an inner roller 2105 and a pair of toothed wheels 2106.

[0139] First and second outer rollers 2104 bear against a smooth outer facing surface of cam track outer wall 2107, whilst inner roller 2105 bears against an inwardly facing surface of cam track inner wall 2108, as the cam track follower follows around the track defined by the inner and outer track walls. First and second toothed wheels 2106 follow around the toothed inwardly facing surface of the outer track wall 2107. The pair of toothed wheels 2106 follower around the toothed inner wall of the outer track 2107.

[0140] When the cam track follower is passing along the substantially flat track portion, the carriage is orientated so that the outwardly facing crimp head follows a substantially straight line path corresponding to the distance of the flat or straight portion of the D Cam track.

[0141] In yet a further variation of the end plates and cam track followers, there may be provided a convex or concave "V" shaped track on an inner or outer face of the inner or outer track walls which has a substantially "V" shaped cross-section as seen in a direction perpendicular to a travel direction along a path defined by said inner and/or outer track walls. The purpose of the "V" shaped profile is to restrict movement of the carriages in a side to side direction parallel to a main length of each carriage when one or more of the end rollers on the carriage has a corresponding opposite concave or convex "V" shape outer profile.

[0142] Alternatively there may be a protruding retaining wall or lip at the periphery of the inner and/or outer track wall to act as a retaining wall which restrains movement of wall of the cam in the side to side direction along a main length axis of the carriage, and perpendicular to a main plane containing a main outer face of the end plate.

Variable parameters [0143] The novel flow wrap packaging machine disclosed herein preferably has fully customisable variable operating parameters to allow the packaging machine to run different package sizes (different package lengths), and different line speeds and to accommodate different packaging material web types. The following parameters may be variable and computer-controlled by means of a computer control system and servo arrangement: * Pack paper length X -being the overall length of the finished package; * product collation length Y -being the overall length of the product within the package; * product collation position -being the offset of the product from the centre of the package, which determines the position of the product within the package; * product width -being the width of the product; * registration position.

[0144] In addition, variable set up and offset parameters of the end crimps can be entered into the machine, said variable parameters comprising.

* A number of jaws per shaft, in the case of a rotating end crimp; * an end crimp natural length * an end crimp home offset actual position * an end crimp home offset home sensor offset Advantages [0145] By providing a track path which has a substantially straight portion, and/or a portion of substantially greater radius than the radius of curvature of the remaining portions of the track path, a pair of opposing crimp heads or sealing heads can be transported over a length of said substantially straight portion or said substantially large radius curved portion with a web of packaging material therebetween. Because the crimp heads travel at the product line speed over that substantially straight distance this enables a greater contact time with the packaging material than is possible with a known circular rotary sealing stage.

[0146] Because the crimp heads travel with the web of packaging material for a longer time than in prior art sealing stages this enables a reduced temperature range for the crimp heads and/or allows a wider range of contact time / temperature / pressure combinations for the opposing sealing heads than is available with prior art sealing heads. For packaging materials which are susceptible to melting under high temperature and/or high-pressure, by having the sealing heads travel with the product items over a relatively larger distance compared to a known rotary circular sealing head, crimp head temperatures can be reduced and / or contact pressure can be reduced, whilst maintaining a higher product line speed compared to a prior art rotary sealing head.

[0147] Compared to known reciprocating "box motion" sealing stages, in the present embodiments, use of a curved loop track having carriages traversing the track in a carousel motion may give improved reliability by reducing the reciprocating mass compared to the box motion machine.

[0148] By independently controlling each of the pairs of crimp heads, this may provide greater flexibility in package length.

[0149] Further, where the crimp heads are electrically heated, heat is drawn out of the crimp heads during the relatively straight portion of the track where the crimp heads are in contact with the packaging material. In the remainder of the loop, heat is absorbed into the crimping heads by an electrical heating element in the crimp heads. Having a relatively straight portion of the path allows a greater distance and therefore a greater time for heat to be transferred from the crimp heads into the packaging material to create an end seal compared to a circular path where there is a relatively short time to transfer heat from the crimp head into the packaging material. This translates into relatively lower temperatures of the crimp head compared to prior art devices, which may lead to lower risk of melting through the packaging material for the package end seals. Additionally, after breaking contact with the packaging material at the end of the straight portion of the loop path, the crimp head has cooled as heat has been transferred to the packaging material. There is a limited time during which the temperature of the crimp head can be raised as it travels around the remainder of the loop track. By being able to lower the temperature of the crimp head, this also makes it easier to input enough heat into the crimp head during the remainder of the return loop before the crimp head starts the next transit across the straight portion of the path.

[0150] In a variation of the end sealing stage, instead of the pairs of carriages being driven by individual servo motors, one per pair, there may be provided linear electromagnetic drives adjacent the tracks which drive the ends of the carriages around the track paths.

[0151] In the foregoing summary and description of specific embodiments, any technical feature present in one embodiment may be substituted for any equivalent technical feature of any other embodiment. Similarly, any technical feature described in relation to one embodiment may be omitted from said embodiment. Similarly, any technical feature described in relation to one embodiment which is not described as being present in relation to another said embodiment may be added to said other embodiment unless otherwise explicitly stated. The individual technical features comprising any of the embodiments described herein may be juxtaposed with other embodiments described herein by addition, substitution or omission, in any order, any permutation, any combination or selection in order to achieve the objects of the invention.

Claims

Claims 1. An end sealing apparatus for a flow wrap packaging machine, said end sealing stage comprising: a cam track; a plurality of carriages arranged to follow said cam track; and a plurality of drive means for driving said plurality of carriages, wherein each said carriage is independently driven by a separate said drive means.
2. The end sealing apparatus as claimed in claim 1, wherein each said carriage is capable of being driven at a variable speed along a path of said cam track independently of one or more other said carriages.
3. The end sealing apparatus as claimed in claim 1 or 2, wherein said cam track follows a closed loop path.
4. The end sealing apparatus as claimed in any one of the preceding claims, wherein said cam track comprises: a substantially straight portion along which said carriages follow a substantially straight path, said straight portion having a first end and a second end; and a curved portion along which said cam followers follow a return loop path between a first end of said straight portion and a second end of said straight portion
5. The end sealing apparatus as claimed in any one of claims 1 to 4, comprising a second plurality of carriages following a second cam track; said first and second cam tracks being spaced apart from each other and lying parallel to each other such that said first plurality of carriages rotate around said first cam track and said second plurality of carriages rotate around said second cam track; wherein each said carriage of said first cam track is paired with a corresponding respective said carriage of said second cam track; and each pair of carriages is driven by a corresponding respective drive train, so that a motion of a first carriage of a said pair is synchronised with a motion of a second carriage of said pair.
6. The end sealing apparatus as claimed in claim 5, comprising control means which independently controls each said pair of carriages, so that each carriage pair can move around their respective tracks at a speed which is different to each other pair of carriages.
7. The end sealing apparatus as claimed in claim 5 or 6, further comprising a set of gears which synchronises a carriage of said first plurality of carriages with a carriage of said second plurality of carriages to create a synchronised pair of carriages, wherein the motion of one carriage within said pair is synchronised with motion of the other carriage of said pair.
8. The end sealing apparatus as claimed in any one of the preceding claims, wherein a said carriage comprises: a main body; a first cam track follower located at a first end of said main body; and a second cam track follower located at a second end of said main body.
9. The end sealing apparatus as claimed in any one of the preceding claims, comprising one or a plurality of cam track plates, each said cam track plate 5 comprising: a plate member, said plate member having an aperture there -through; an outer track wall; and an inner track wall, wherein said outer and inner track walls define a path there between.
10. The end sealing apparatus as claimed in any one of the preceding claims, wherein each said carriage comprises a first track follower on a first side of said carriage, arranged to follow around a first track on a first track plate; and a second track follower on a second side of said carriage, arranged to follow around a second track on a second track plate.
11. The end sealing apparatus as claimed in any one of the preceding claims, wherein a said track is defined by a track plate, said track plate comprising an outer track wall and an inner track wall, said outer and inner track walls defining a path there between.
12. The end sealing apparatus as claimed in any one of the preceding claims, wherein each said drive means comprises: a corresponding respective electric motor; and a corresponding respective drive transmission shaft.
13. The end sealing apparatus as claimed in claim 12, wherein a plurality of said drive transmission shafts are arranged coaxially along a single axis of rotation, each said drive transmission shaft having an angular range of movement over which it can move independently of each other said drive transmission shaft.
14. An end sealing apparatus for a flow wrap packaging machine, said end sealing stage comprising: 1 0 a first carousel having a first set of carriages; a second carousel having a second set of carriages; a first drive means for driving a first one of said first set of carriages in synchronisation with a first one of said second set of carriages; a second drive means for driving a second one of said first set of carriages in synchronisation with a second one of said second set of carriages; wherein each of said first and second drive means are independently controllable.
15. The end sealing apparatus as claimed in claim 14, further comprising: a third carousel having a third set of carriages, and a third drive means for driving a third one of said first set of carriages in synchronisation with a third one of said second set of carriages.
16. The end sealing apparatus of claim 14 or 15, further comprising: a first synchronisation means for synchronising a motion of said first one of said first set of sealing heads with a motion of a first one of said second set of sealing heads; and a second synchronisation means for synchronising a motion of said second one of said first set of sealing heads with a motion of a second one of said second set of sealing heads.
17. The end sealing apparatus as claimed in claim 16, further 10 comprising: a third synchronisation means for synchronising a motion of said third one of said first set of sealing heads with a motion of a third one of said second set of sealing heads.
18. The end sealing apparatus of any one of claims 12 to 17, wherein: said first drive means comprises a first motor; and said second drive means comprises a second motor.
19. The end sealing apparatus of any one of claims 12 to 18, wherein said first and/ or second drive means comprises a drive means selected from the set: an electromagnetic linear drive; an electromagnetic rotary drive.