RU2575082C2 - Perfected method and plant for production of corrugated cardboard - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to production of corrugated monolayer sheet from porous material in a continuous process. Note here that claimed plant comprises crimping shaft, grooved roll to apply the discrete dips of glue on ridges of just-made corrugated sheet. Endless crimped belt conveyor assembly with endless crimped surface provided with multiple abutting crimps. Note here that configuration of crimps complies with the crimping shaft teeth. Clamping mechanism is meant for retention of just-made crimped sheet on crimped belt conveyor during glue application by glue applicator. Endless tighten belt is meant for retention of the flat sheet jointly with corrugated sheet for gluing them together. Note here that clamping mechanism is composed of a vacuum pump arranged upstream of endless crimped conveyor belt.

EFFECT: perfected method.

3 cl, 15 dwg

Description

FIELD OF TECHNOLOGY

The present invention relates to an improved method and installation for the manufacture of corrugated cardboard. In particular, the present invention discloses a method and apparatus for manufacturing a two-layer corrugated cardboard, and / or in some embodiments, for the manufacture of a three-layer corrugated cardboard.

BACKGROUND

For ease of understanding only, the present invention will be described with an example of manufacturing a two-layer paperboard, however, this option should not be considered limiting, since some embodiments of the present invention can be used for the manufacture of a three-layer corrugated paperboard.

As applied to this description, the terms “corrugated” and “corrugated”, as well as their grammatical forms, are used interchangeably and refer to a sequence of alternating protrusions (ridges) and grooves (grooves).

Double-layer corrugated cardboard is well known and widely used in industry, especially for packaging, where it acts as a protective gasket and wrapper. It is also used as a basic component in the production of standard cardboard (i.e., three-layer corrugated cardboard) and many structural products, for example, boxes, panels, pallets, etc.

Sheets of double-layer corrugated cardboard can be glued together for the manufacture of multilayer corrugated cardboard of various thickness and strength. One of the reasons for the widespread use of corrugated board is that it is a relatively lightweight, tough and durable material.

Double-layer corrugated cardboard is made by gluing corrugated sheet material (usually obtained from recycled paper) on the front sheet. The face sheet is typically made of kraft paper, but other materials may be used.

In a traditional installation for manufacturing a two-layer corrugated (also called corrugated) cardboard, a corrugated sheet is formed by passing a sheet of paper between two corrugating shafts. These two shafts are arranged so that the teeth located on the outer surface of each of the shafts engage with each other. A sheet of paper is fed between the teeth of these shafts, and as a result of mutual engagement of the teeth, the paper takes the form of corrugations. The corrugated sheet is held in contact with the teeth on the outer surface of one of the corrugating shafts, typically using a vacuum created inside the corrugating cylinder, at least until the face sheet enters.

A line of adhesive is applied to the crests of the corrugations for gluing the face layer to the corrugated paper. Typically, the face sheet of paper is pressed against the ridges with a smooth shaft so that the face layer adheres to the corrugated paper, thereby forming a two-layer corrugated (or corrugated) cardboard.

The limiting factor in this process is the need to keep the corrugated sheet in contact with the face for a period of time sufficient for the adhesive to seize and form a glued joint. This period of time at ordinary room temperature and pressure may be several seconds or more. However, in traditional processes, this time is shortened by increasing the temperature during the gluing process, as well as by applying pressure to the junction between the ridge and the face layer.

To heat the cylinders along which the corrugated paper and the front layer move, high pressure steam is usually used, as a result of which the temperature of the paper rises. Typically, the operating temperature range of the corrugating shafts may be approximately 150-200 ° C.

Pressure to the joints between the liner and each crest can be applied under the influence of a pressure roller set so as to press the face layer against the ridges coated with adhesive. Since the contact time between the pressure roller and the corrugating shaft (which holds the corrugated sheet) is relatively short, high pressure is usually required to significantly speed up the bonding process.

With this type of process organization (heating plus high pressure), the gluing time can be reduced to a few hundredths of a second, which makes it possible to produce two-layer cardboard with high speed. However, one of the problems with this process organization is that the high pressure applied by the pressure roller can deform the paper and leave ugly marks on the surface of the face layer of the paper, which reduces the value of the finished product.

In some installations, other devices are used to press the front sheet to the grooved one as they move around the corrugating shaft, for example, endless belts. Since in this case the duration of the application of pressure increases, lower pressure values can be applied in order to avoid deformation of the cardboard surface.

A typical construction of an apparatus for manufacturing two-ply paperboard, generally described above, is disclosed in US Pat. No. 5,951,817 to Thomas.

In the equipment described in US Pat. No. 5951817, the duration of contact between the corrugated sheet and the front (and therefore the bonding time) is limited since the corrugated sheet / face layer is in contact with only one third of the circumference of the corrugated wheel. Such limited contact times require the use of quick-setting adhesives, such as, for example, starch-based adhesives commonly used in the industry. Unfortunately, activation of starch-based adhesives requires heating (to a temperature of about 150 ° C. or so). This leads to the problems described above.

The use of heating can reduce the time required for the formation of a glued joint between the corrugated sheet and the front, allowing to obtain a high production speed, however, this requires solving a number of technical issues, which significantly increases the cost of equipment and the cost of the process. The use of high-pressure steam requires the presence of boilers, pipelines and housings that ensure the constant presence of steam in an enclosed space. Additional safety measures must also be taken to ensure proper steam production and handling, as well as no risk of damage due to steam heating during machine operation. In a typical case, the operation of the boiler and the maintenance of the heating system requires the presence of a heating engineer, which adds to the cost of skilled labor, and also leads to the potential for stopping production in the absence of an engineer with the appropriate qualifications.

Adding a high-pressure steam system to the basic elements of the machine inevitably leads to an increase in the size of the machine, and, consequently, to an increase in the space required for its operation. The requirement of additional space increases production costs for the manufacture of two-layer corrugated cardboard.

In addition, high-pressure steam has a significant corrosive effect on many materials, so machine parts exposed to steam, such as corrugating shafts, must be made of corrosion resistant materials. Such materials, for example, 48 CrMo steel alloy hardened to HRC 58-62, are usually expensive and heavy. An installation made of such materials may require an appropriate support structure to maintain the structural integrity of the machine.

The problem associated with both methods of applying pressure (using a roller and using a belt) is that under the influence of the applied pressure, a part of the adhesive can be squeezed out of the contact points between the face layer and the crest of the corrugated sheet, which will moisten nearby areas of the paper. Extruded from the ridge (i.e., from the contact line), the adhesive will not dry out as fast as the adhesive on the ridge, since it will not be pressurized, and will typically not form an adhesive bond between two sheets of material. As a result, an excess (squeezed out) of the adhesive will remain wet longer, which will lead to problems in the form of deformation of the cardboard, since it will dry at different speeds, and cutting the cardboard or its further processing will be difficult until it is completely dry. A common solution to this problem is additional heating to dry the paper and excess (squeezed out) adhesive. However, this increases production costs and may limit the speed of the process.

The squeezed out adhesive can also get on the surface of the device applying pressure (for example, on a roller or belt), as a result of which such a surface will need to be constantly cleaned. In addition, a part of the squeezed out adhesive substance may fall onto the outer surface of the face layer, which can lead to problems during storage on a roll, since adjacent sheets can stick together with each other, rendering the product unusable. In addition to this, excessive adhesive can leave marks on the surface, impairing the appearance and reducing the value of corrugated board.

Another drawback of traditional machines is that, in a typical case, both the feed rollers (used to feed paper intended for corrugation and for use as a front layer), and the corrugating rollers are heated to dry the paper before application sticky substance. This is done in order to reduce the moisture content of the paper and to reduce the sticking time. The production of high-pressure steam to heat the corrugating shafts and preheat the paper can require significant energy costs. All of the above factors can significantly increase the cost of double-layer corrugated cardboard made using traditional processes and machines.

The applicant tried to solve many of these issues earlier in PCT application WO 2009/145642. However, it would be useful to have a method and a formula that could be applied to:

- manipulating the configuration of the machine; and / or

- accurate prediction of production speed;

in the manufacture of corrugated sheet material using a cold process.

In particular, it would be useful to have an optimized production method.

Earlier in the application WO 2009/145642, the applicant considered that the production speed is determined by the diameter and rotation speed of the second (larger) corrugating shaft. The applicant also considered it a fact that an endless belt covering three quarters of the circumference of the second corrugating shaft fixes a rotation speed of about 20 revolutions per minute. The applicant noted that for the second corrugating shaft with a diameter of 1.6 m, the production rate of a three-layer corrugated cardboard was approximately 100 m / min.

However, it soon became apparent that the above production speed value was a very rough estimate, and that a more accurate formula for determining the production speed was needed to design a machine for the production of double-layer corrugated board so that it was sure that the machine would meet the expected need . The need for a more accurate formula for determining productivity is urgent, especially in view of the time, costs and funds required for the manufacture of a corrugating machine. It would be useful to have a more accurate way to determine production speed in advance.

Currently, due to the use of heat in the manufacture of corrugated sheet material, it is not possible to glue sheet material with pre-printed information directly onto the corrugated sheet material, since high temperature can damage the print.

Therefore, flexographic printing with rubber stereo forms is usually used for printing information, but this method leads to damage to the corrugations of the corrugated sheet material, since it involves applying pressure to apply paint to the face layer adhered to the corrugated sheet material. Some wrinkling of corrugations with rubber stereo forms during flexographic printing leads to a decrease in the strength (i.e., structural strength) of the cardboard. In addition, the print quality of the ink rollers on the cardboard can be quite low, for example, such as can be seen on many boxes for apples or other fruits.

Therefore, it would be useful to obtain a method for gluing sheet material with pre-printed information directly on corrugated sheet material, and that this method is part of a continuous in-line process for manufacturing a two-layer or three-layer cardboard. In particular, it would be advantageous to have a method for forming a face layer from a sheet of pre-printed information, since this reduces the amount of material, production steps and time required for the manufacture of boxes and other advertising materials from corrugated cardboard.

Another problem with traditional corrugating equipment is that:

- the paper is heated; in conjunction with

- constant adjustable braking force applied to the paper exiting the roll holder to direct it along a straight path;

as a result, the resulting corrugated cardboard has bends at the corners, and, therefore, is not a perfectly flat sheet (as seen with the naked eye), which would be a more valuable waste-free final product.

Continuous braking is required because when the paper is wound on a roll at a pulp and paper mill, it is exerted by forces stretching left and right, which leads to its deviation from the straight path when unwinding the roll.

The present invention seeks to solve the above problems or to at least provide the public with a useful choice.

All materials referenced in this description, including all patents or patent applications, are incorporated herein by reference. None of the materials cited is part of the state of the art. When considering reference materials, what is claimed by their authors is indicated, and the applicant reserves the right to question the accuracy and relevance of the cited documents. It should be clearly understood that, although there may be references to a number of publications related to the current level of technology, this reference material does not contain recognition that any of these documents is part of general knowledge in this field in New Zealand or in any other country .

It is generally recognized that the term “contains” can be used either in an exclusive sense or in an inclusive sense, depending on the field of activity. As applied to this description and unless otherwise specified, the term “contains” has an inclusive meaning, i.e. it should be understood as including not only the listed components to which it directly points, but also other, not specified, components or elements. The same principle applies to the use of the term “comprises” or “comprising” with respect to one or more steps of a method or process.

Other aspects and advantages of the present invention will be apparent from its description, set forth below by way of example only.

SUMMARY OF THE INVENTION

As applied to this description, the term “continuous process” refers to a process in which corrugated sheet material can be adhered to a flat sheet material immediately after the formation of the corrugated sheet material by means of the larger and smaller corrugating shafts engaging with each other, forming corrugations preliminarily on flat sheet material, which makes it possible to produce two-layer cardboard in a single continuous (i.e., not interrupted) process.

In accordance with one aspect of the present invention, there is provided a method for bonding a substantially flat porous sheet material to a corrugated porous sheet material in a continuous process, said method being characterized by the following steps:

a) applying a metered amount of adhesive to the upper contact portion of the corrugated sheet material; and

b) holding the corresponding flat and corrugated sheets pressed against each other by pressure of a predetermined value for a predetermined pressing period to form a connection between them.

Steps a) and b) are preferably carried out at ambient temperature.

In some preferred embodiments, the adhesive is applied and set at ambient temperature. In other embodiments of the invention, the adhesive may be heated prior to application (depending on the type of adhesive used), but in all such embodiments of the invention, the selected adhesive should be able to set at ambient temperature.

As applied to this description, the term “upper contact portion” refers to the upper part of the corrugation crest of the corrugated sheet material, to which, as a protruding support, a flat sheet is pressed in step b) of the process. The upper contact area includes the top of the ridges and that area on each side to which the flat (front) sheet is directly pressed, and then glued using the applied adhesive. The inventor found that in the case of an adhesive sticking out of the upper contact portion on the sides of the corrugations, significant problems arise. These issues include:

- an increase in gluing time, caused by the fact that the pores of the face layer cannot absorb moisture if the adhesive is outside the upper contact area;

- overspending of the adhesive;

- the formation of grooves on the corrugations;

- bending of cardboard, if this two-layer cardboard is used for the manufacture of three-layer cardboard.

The set pressure value in the preferred embodiment should be selected as high as possible, without causing a violation of the integrity of the paper. In preferred embodiments of the invention, this predetermined pressure value is less than the tensile strength of the selected porous sheet materials. The inventor determined that the higher the preset pressure value, the shorter the bonding time.

Typically, the porous sheet material may be paper, but it may also include other sheet materials with similar characteristics that can be used to make corrugated board. A key characteristic of such a sheet material is sufficient porosity to absorb most of the moisture contained in the adhesive at a given predetermined pressure.

In accordance with another aspect of the present invention, there is provided a method for bonding a substantially flat porous sheet material to a corrugated porous sheet material using the continuous process generally described above; wherein the production rate is calculated by the formula:

RP = DHT / BT,

where RP is the production rate in meters per minute, DHT is the distance in meters over which two corresponding sheets are held pressed together, and BT is the setting time of the adhesive in minutes.

In accordance with another aspect of the present invention, there is provided a method of manufacturing an apparatus equipped with large and small corrugating shafts engaged with each other for the continuous production of a two-layer porous sheet material; in the specified method, the formula is used:

RP = DHT / BT

to determine the diameter of the large corrugating shaft and the percentage of the circumference of the large corrugating shaft, on which the endless belt must exert pressure to provide the required production speed;

here RP is the production rate in meters per minute, DHT is the distance in meters, over which two corresponding sheets are held pressed against each other, and BT is the adhesive setting time in minutes.

In accordance with another aspect of the present invention, there is provided an apparatus for gluing a substantially flat porous sheet material to a corrugated porous sheet material to produce a two-layer corrugated porous sheet material, which is part of a continuous process involving a large corrugating shaft and a smaller corrugating shaft, as well as an adhesive applicator and endless tension belt; the production rate for this installation is determined by the formula:

RP = DHT / BT,

where RP is the production rate in meters per minute, DHT is the distance in meters over which two corresponding sheets are held pressed together, and BT is the setting time of the adhesive in minutes.

In relation to this description, the term "predetermined pressing period" refers to the setting time of the adhesive substance (BT), calculated by the formula:

BT = DHT / RP,

where RP is the production rate in meters per minute, and DHT is the distance in meters over which two corresponding sheets are held pressed against each other;

If the installation of the present invention contains a larger diameter corrugating shaft that engages with a smaller diameter corrugating shaft, then the DHT value is defined as: DHT = X. (Π2r), where r is the radius of the larger corrugating shaft, and X is the percentage of the circle From a large corrugating shaft, which can be pressurized by an endless tension belt, while leaving enough space for the adhesive applicator and smaller corrugating shaft. The maximum X values increase as the diameter of the larger corrugating shaft increases, as will be described below.

For the purposes of this description, the terms “large shaft”, “large diameter corrugating shaft” or “large diameter corrugating shaft engaging” or the like are used interchangeably and refer to a corrugating shaft whose diameter is at least twice the diameter of a “smaller shaft diameter ”,“ smaller diameter corrugating shaft ”or“ smaller diameter corrugating shaft meshing ”.

In accordance with another aspect of the present invention, there is provided an apparatus for gluing a substantially flat porous sheet material to a corrugated porous sheet material for manufacturing a two-layer corrugated porous sheet material in a continuous process, said installation comprising a large diameter corrugating shaft that engages with a smaller corrugating shaft diameter, and an endless tension belt, positioned so as to apply pressure to uzhnuyu lateral surface of a large embossing shaft, facilitating gluing of plane and corrugated sheets; the circumference of the corrugating shaft of large diameter, which can be pressurized by an endless tension belt, is determined by the formula:

C = (RP.BT) / X,

where C is the circumference of this shaft (i.e. π2r), RP is the production rate in meters per minute; BT is the setting time for the adhesive in minutes, and X is the maximum percentage of the circle that the endless tension belt can exert pressure on.

In accordance with another aspect of the present invention, there is provided an apparatus for gluing a substantially flat porous sheet material to a corrugated porous sheet material to form a double layer corrugated porous sheet material in a continuous process; wherein said installation comprises a large-diameter corrugating shaft that engages with a smaller-diameter corrugating shaft, and an infinite tension belt located so as to apply pressure to the lateral outer surface of the large corrugating shaft, contributing to the formation of a layered structure of flat and corrugated sheets; in this case, the percentage of the circumference of the large corrugating shaft, on which the endless tension belt does not exert pressure, is limited exclusively by the minimum space necessary to accommodate the smaller corrugating shaft and the adhesive applicator.

The inventor determined that the factor limiting the production rate is determined to a greater extent not by the speed of rotation of the corrugating shaft (rpm), but by the formula:

RP = DHT / BT,

where RP is the production rate in meters per minute, DHT is the distance in meters over which two corresponding sheets are held pressed together, and BT is the setting time of the adhesive in minutes.

In a preferred embodiment, the configuration of the tension belt device allows pressure to be applied to 70% -93% of the circumference of the large corrugating shaft.

In preferred embodiments of the invention, the author has determined that the diameter of a large corrugating shaft, the value of which can be almost any in the range 0.4 m - 2.0 m, determines the maximum percentage of the circumference of the largest corrugating shaft that an endless belt can cover, leaving enough spaces for:

- glue applicator, which includes a glue roller; and

- smaller corrugating shaft.

For example, for a large shaft with a diameter of 0.4 m, the maximum percentage of a circle that an endless belt can cover is almost 70%, and for a large shaft with a diameter of 2 m, the maximum percentage of a circle that an endless belt can cover is almost 93%.

The inventor has determined that the average value of the arc length of the circumference of a large shaft, required to accommodate an adhesive roller and a smaller corrugating shaft in the above embodiment, is approximately 0.45 m-0.5 m.

In a preferred embodiment, the large corrugating shaft may have a diameter of 0.62 m and the endless belt exerts pressure on approximately 76% of the circumference of the large shaft.

In another embodiment, the large corrugating shaft may have a diameter of 2 m and the endless belt exerts pressure on approximately 93% of its circumference.

In accordance with another aspect of the present invention, there is provided a method for operating a large diameter corrugating shaft that engages with a smaller diameter corrugating shaft and an endless tension belt, comprising a pressing step in which the tension belt is positioned so as to apply pressure to a portion of a side outer surface a large corrugating shaft for forming a glued joint between a substantially flat porous sheet material and a corrugated porous sheet material ialom comprising the additional step of applying a large percentage of the value corrugation shaft circumference covered belt, to determine the rate of production.

In accordance with another aspect of the present invention, there is provided a method of using a tension belt and a large diameter corrugating shaft meshed with a smaller diameter corrugating shaft, as well as an adhesive applicator for manufacturing a double layer corrugated cardboard from a porous flat sheet material and a porous corrugated sheet material; said method comprises the step of applying an adhesive substance to the corrugated sheet material at ambient temperature, followed by holding the respective flat and corrugated sheets pressed against each other by a tension belt for a predetermined period of time.

The inventor determined that the maximum production speed for the installation, including corrugating shafts of large and smaller diameters entering into engagement with each other, is determined by the formula:

RP = X (π2r). BT,

where RP is the production rate in meters per minute, BT is the setting time of the adhesive in minutes, and X is the percentage of the circumference of the large corrugating shaft, on which the endless tension belt exerts pressure.

Installation for the manufacture of two-layer corrugated cardboard from porous sheet material, characterized in that the maximum production speed of this installation is determined by the formula:

RP = X (π2r). BT,

where RP is the production speed in meters per minute, BT is the adhesive setting time in minutes, and X is the percentage of the circumference of the large corrugating shaft that the endless tension belt can exert pressure on.

A method in which a large corrugating shaft and an endless tension belt are used, and characterized in that the maximum production speed is determined by the formula:

RP = X (π2r). BT,

where RP is the production rate in meters per minute, BT is the setting time of the adhesive in minutes, and X is the percentage of the circumference of the large corrugating shaft, on which the endless tension belt exerts pressure.

As an explanation, it should be noted that in the above formula, the maximum production speed for the engaging corrugating shafts of large and smaller diameters is calculated based on the circumference of the roller (i.e., π2r) multiplied by the value X, which is a percentage of the circle , on which an infinite tension belt can exert pressure, and multiplied by VT.

In a preferred embodiment, the RP value is in the range of at least 25 m / min. - 200 m / min.

In a preferred embodiment, the sheet material is kraft paper.

Kraft paper is usually used for the manufacture of two-layer corrugated cardboard. However, as mentioned above, other porous sheet materials can be used for the present invention, and therefore, the reference that the sheet material is kraft paper to be found in this description should not be considered limiting.

Flat sheet material, known as front, can also be made from kraft paper.

The term “substantially flat” should be considered to refer to a sheet or roll having an almost flat surface lying in one plane (at least when viewed with the naked eye).

In contrast, the term “corrugated” should be considered to refer to a sheet or roll, the surface of which is an alternating sequence of ridges and grooves (ie, corrugations).

The corrugations on the corrugated sheet used to make the two-layer corrugated board are commonly called corrugations. Typically, the corrugations are formed by passing a sheet of kraft paper through a pair of corrugating shafts arranged in such a way to each other that the teeth of these corrugating shafts engage with each other on both sides of the kraft paper. The shape of the corrugations obtained depends on the shape and size of the teeth of the corrugating shafts. A non-limiting list of examples of the shape of the corrugations includes a triangular, sinusoidal, trapezoidal, sawtooth, diamond-shaped, square or any other repeating wave-like shape. Similarly, the size of the corrugation is determined by the equivalent size of the teeth and may vary depending on the end use of the given two-layer corrugated cardboard.

In a preferred embodiment, the corrugated sheet material has corrugations with a substantially triangular cross-sectional profile.

The advantage of the almost triangular profile of the cross section of the corrugations is the relative simplicity of forming such corrugations with the help of teeth formed in a standard way on the corrugating shafts.

In addition, triangular corrugations may have additional strength compared to some other forms, especially with respect to compression along the length of the corrugation.

If the facing and corrugated sheets are made of kraft paper, then, as a sticky substance, for gluing the face layer to the upper contact portions of the corrugated sheet, water-based glue is typically used.

This adhesive may also be non-aqueous based, provided that when applied to the upper contact areas, it behaves like a liquid and can be absorbed by the porous sheet material in accordance with the present invention.

The term “metered amount of adhesive” refers to a measured amount of adhesive that is applied to the upper contact area so that it does not extend beyond this upper contact area before or during the joining of step b). Therefore, a “metered amount of adhesive” can mean a drop of glue, an adhesive coating or droplets of glue that are placed or applied along the upper contact portion of each crest of the corrugated sheet.

The dosage form of the adhesive may vary depending on the application mode.

In some embodiments, these dosage amounts may be applied in the form of a thin line, smear, grid of intersecting lines, a dashed line (s), or a dashed line (s).

A key factor for obtaining the connection between the respective sheets is to ensure that the adhesive first moistens the corrugated sheet and penetrates into it, and then so that it moistens the second (front) sheet and penetrates into it.

The use of dosage allows you to apply a smaller amount of adhesive on the corrugated sheet than in traditional methods. In addition, due to the dosage, the adhesive does not extend beyond the upper contact area, especially during step b). Therefore, the use of a metered amount allows a portion of the adhesive extruded by the pressure applied to the facing and corrugated sheets to fall onto dry areas of the respective sheets.

In one preferred embodiment of the invention, the adhesive is applied to the upper contact area in the form of spaced apart droplets practically as described in PCT application WO 2009/145642 previously filed by the applicant, where the droplets are applied to the comb.

It is understood that droplets may be small amounts of a round or pear-shaped adhesive sticking to the surface, but this should not be considered a limiting option.

The preferred droplet size may depend on a number of factors, including the properties of the corrugated paper and the face layer, as well as the type of adhesive used. However, in all cases, the droplets must be small enough to maintain their shape and not flatten under their weight. This is important because a relatively high ratio of volume to surface area (compared to, say, a strip or line of adhesive) reduces the rate of evaporation of moisture from the droplet, thereby increasing the time during which a drop of adhesive can wet the corrugated paper comb and face layer and soak in them before this sticky substance dries.

A preferred droplet volume is about 0.5 mm ³ . The preferred size of the gap between the droplets is calculated based on the desired thickness of the adhesive film layer, so that after flattening the applied droplets to a layer of the desired thickness, they merge with each other.

In another preferred embodiment, the adhesive is applied to the upper contact portion in the form of a thin continuous drop (i.e., an adhesive line).

The applicant has determined that this method can be used to produce a two-layer corrugated board without using heat to form a joint between the corrugated sheet material and the front sheet material.

As applied to this description, the term "ambient temperature" refers to the temperature of the room / building where this installation can operate and implement the method of the present invention. In general, the ambient temperature is a temperature in the range between 5 ° C-60 ° C. The most preferred ambient temperature may be a temperature in the range between 10 ° C.-25 ° C.

It should be understood that the choice of adhesive is important for the present invention. As noted in the section "prior art", the activation of adhesive substances based on starch requires a temperature of about 150 ° C. Therefore, such an adhesive is undesirable for use in the present invention if it is not activated before use (for example, by heating in a storage tank). Acceptable adhesives capable of quickly setting at room temperature and providing the required bond strength will be discussed later in this description.

A significant advantage of the present invention is that it allows the manufacture of corrugated cardboard without heating the bonded porous materials. Further in this description, it will be shown that this eliminates the need to buy expensive equipment and significantly reduces energy consumption. It is understood that applying a metered amount of the adhesive to the upper contact portion of the porous corrugated sheet at sufficient pressure provides a significant advantage in the form of a reduction in bonding time at ambient temperature.

In a second step of the method of the present invention, the face sheet is held pressed against the corrugated sheet under pressure of a predetermined value for a predetermined time sufficient to form a joint. This can be achieved by various means.

In a preferred embodiment, the flat (front) sheet is pressed against the corrugated (corrugated) sheet under the influence of a tensioner with an endless belt.

The process of applying pressure to the face sheet to press it against the corrugated sheet using an endless tension belt is well known in the art, and therefore does not need to be considered in detail.

As applied to this description, the term “predetermined pressure” refers to the pressure that is applied by the belt to a large surface of the corrugating shaft and whose value is set equal to the maximum value (or slightly lower) of the pressure that can be applied without causing deformation of the paper (face and corrugated paper) . Excessive pressure can cause wrinkling and / or tearing of paper. This maximum pressure will vary depending on the material of the front and corrugated paper.

In a preferred embodiment, the sheet materials are held pressed against each other for at least two seconds.

The applicant has determined that when using an endless belt (stretched to hold the cover sheet firmly against the ridges, without damaging the cover sheet) in combination with a suitable commercially available adhesive, it is necessary to hold the front and corrugated sheets pressed together to ensure a reliable connection between the face and corrugated sheets to each other at room temperature for longer than approximately two seconds (pressing time).

In a typical case, if the pressing time is less than two seconds, or if the pressure between the sheets is too small, the two-layer cardboard will not be formed completely or properly. In such cases, the stress in the corrugated sheet will be large enough to break the connection, as a result of which the front sheet will come off from the corrugated sheet.

Practical considerations dictate that the retention time at room temperature be two to four seconds; in a preferred embodiment, the pressing time is approximately three seconds. Pressing times in excess of four seconds can be used, but they are not preferable because they can significantly reduce the production speed of a two-layer corrugated cardboard if the size of the corrugating shaft is not increased.

However, the formula derived by the inventor that defines the set value of the processing time allows a qualified specialist in this field to manipulate the installation configuration to achieve higher production speeds within the physical properties of the paper and adhesive used.

The pressing time within about two or three seconds is significantly longer than the time achieved in some existing plants that use a combination of high temperature and high pressure. However, an advantage of the present invention is that it allows the production of a certain amount of double-layer corrugated cardboard at an acceptable rate at room temperature. This allows you to get the process and installation for the production of two-layer corrugated cardboard with a reduced cost, safe and environmentally friendly way.

The inventor believes that the combination:

- the use of a metered amount of adhesive;

- applying a sticky substance to the upper contact portion of the corrugated sheet;

- keeping the corrugated and flat sheets pressed together for a predetermined pressing time in order to form a joint; and

- the use of an adhesive substance capable of setting at ambient temperature;

will allow for the industrial production of three-layer corrugated cardboard using a cold process.

In a preferred embodiment, the adhesive is a water-based adhesive suitable for bonding porous materials such as paper. In preferred embodiments, the adhesive may be a dispersion containing a vinyl acetate copolymer.

A water-based adhesive substance containing a vinyl acetate copolymer in dispersion may be preferred because it is a harmless substance under normal conditions of use and, therefore, can be safely used under normal ventilation.

Vinyl acetate copolymer dispersions can set relatively quickly at room temperature and, unlike starch based adhesives, do not require a high temperature for activation. They may have low viscosity, good adhesion and long open exposure times. A relatively low viscosity is required for the adhesive to flow well (for example, when transferred from an adhesive applicator to a corrugated sheet), and good adhesion provides the ability to quickly adhere to the surface.

Open exposure time is such a time interval during which, under conditions of normal temperature and pressure, the surface of the adhesive can remain open before it loses its ability to wet the opposite surface and penetrate the capillaries of the opposite surface. This wetting and penetration is required to form an effective bond between the corrugated paper and the lining. An adhesive with a relatively long open exposure time is preferred because such an adhesive can remain open for some time for atmospheric access before being applied to the corrugations.

A preferred adhesive is Adhesin ™ Z9129W, a vinyl acetate copolymer available from Henkel New Zealand Limited. Applicant has discovered that Adhesin ™ Z9129W has the required viscosity and long open exposure times required for the use of the present invention. For example, the viscosity of Adhesin ™ Z9129W adhesive is in the range of 2100-2200 mPa · s, and the open exposure time is from 0.5 to 1 minute. However, it is possible to use other adhesive substances with similar properties.

Applying a sticky substance (for example, such as Adhesin ™ Z9129W) in the form of droplets on a ridge of a corrugated sheet and keeping the face layer pressed against the ridge for about 3 seconds to form a connection between the corrugated sheet and the lining provides several important advantages over existing methods. In particular, this method can be used to produce double-layer corrugated cardboard at ambient temperature. As a result, the need for heating the corrugating shafts or drying the two-layer corrugated board is eliminated. This can be manifested in a significant reduction in energy consumption, and, consequently, in a reduction in the cost of cardboard production.

In some preferred embodiments of the invention, the adhesive applicator for applying a metered amount of the adhesive comprises a roller whose outer surface has a raised surface.

Another acceptable adhesive was Adhesin ™ Z9040, which takes approximately 2 seconds to form a joint between the corrugated and face sheets.

The relief surface may take a number of forms, and in one embodiment of the invention, it may be a recessed surface or a rough surface. In some embodiments, the embossed surface may be in the form of a U-shaped groove. Said roller in some embodiments may be similar to an anilox roller.

However, in a preferred embodiment, the embossed surface has a shape consisting of small corrugations resembling a square wave.

In one preferred embodiment, the embossed surface may be a corrugated surface. It should be understood that the term "corrugated surface" refers to a surface formed by a sequence of ridges and grooves.

In one preferred embodiment of the invention, ridges (and grooves) are arranged substantially parallel to each other, extending around the circumference of the roller.

In one preferred embodiment, the ridges form a spiral.

In other embodiments, the ridges may form concentric circles.

In a preferred embodiment, ridges and grooves can be formed by cutting (or forming in another way) a V-shaped or square groove on the surface of the glue roll. In fact, the shape of the groove is not critical, but the V shape is preferable because it is quite easy to cut into a smooth cylindrical surface.

During operation, the adhesive can be supplied to the adhesive roller using a pick roller.

Alternatively, injection nozzles or an air scraper extending through a groove may be used.

In an embodiment of the invention with a pick roller, this pick roller is preferably mounted close to the adhesive bath so that when the pick roller is rotated, its outer surface is coated with the stick.

The glue roller is mounted in such a way with respect to the pick roller so that the ridges of the glue roller are firmly pressed against the surface of the pick roller. In this way, the adhesive substance is transferred from the surface of the pick roller to the grooves of the surface of the adhesive roller; however, a small amount of the adhesive substance is applied to the ridges of the glue roller or it is not applied at all.

The gap between the pick roller and the glue roller determines the amount of glue applied.

In a preferred embodiment, the glue roller is also mounted so that the ridges of the application roller are firmly pressed against the ridges of the corrugated sheet on the corrugating shaft. With this arrangement, as the glue roller rotates, it receives adhesive from the pick roller into the grooves on its surface, and then applies this adhesive in the form of droplets onto the ridges of the corrugated sheet.

The amount of adhesive in each droplet can be determined by the size (width and depth) of each groove, and the interval between the droplets can be determined by the distance between adjacent grooves.

It should be understood that the grooves should be small enough to avoid applying too much glue to the corrugated sheet material. In other words, the dimensions of the grooves must be such that the adhesive is applied only to the upper contact areas. In a preferred embodiment, the groove depth is 0.5 mm and the groove width is approximately 1 mm.

In one preferred embodiment, the ridge may be in the form of a sharp edge.

A preferred arrangement of the V-grooves is such that each groove is adjacent to an adjacent groove to form a sharp edge, whereby the cross section of the groove sequence has a continuous zigzag shape. This arrangement allows you to get the minimum intervals between adjacent droplets (for a given width of each groove).

In some other embodiments of the invention, the ridges may have a flat cross section, in which case the intervals between the droplets may be correspondingly larger.

The glue roller is mounted rotatably so that the outer surface (ridges) of the glue applicator is pressed against the ridges of the corrugated paper held on the second corrugating shaft.

In accordance with another aspect of the present invention, there is provided a method for bonding a substantially flat porous sheet material to a corrugated porous sheet material in a continuous process; this method is characterized by the following steps:

a) applying a sticky substance to the corrugated sheet material using a glue applying roller (NK) having transverse grooves located from left to right, extending around the circumference of the NK roller and pressing against the teeth of the corrugating shaft; at the same time, the specified amount of glue contains in the indicated grooves of the NK;

b) holding the corresponding flat and corrugated sheets pressed against each other with a given pressure and for a predetermined time to form a connection between them.

The dimensions of the grooves on the surface of the roller NK allow:

- contain in them a strip of adhesive substance;

- enter into them the teeth (or parts thereof) of the corrugating shaft and the upper contact portion of the corrugated sheet;

as a result, a line of adhesive can be applied to the upper contact portion of the corrugated sheet.

In accordance with another aspect of the present invention, there is provided an apparatus for manufacturing a two-layer corrugated board by gluing a porous corrugated sheet material having one or more ridges onto a substantially flat porous sheet; however, this installation includes:

- glue applicator, the configuration of which allows applying an adhesive substance to each crest of corrugated sheet material; and

- a clamping mechanism designed to press the flat sheet material to the crest of the corrugated material;

characterized in that

the configuration of the application device allows the dosage amount of adhesive to be applied to the upper contact areas of each crest of the corrugated sheet material, and the configuration of the clamping mechanism allows the flat sheet material to be pressed against the corrugated sheet material with a predetermined pressure value, holding it for a predetermined time to form a joint between them .

Accordingly, the apparatus for manufacturing the two-layer corrugated board of the present invention has many of the same characteristics as some existing machines. In particular, a corrugated sheet is formed by passing sheet material between the meshing teeth of the first and second corrugating shafts. The corrugated sheet is held on a second corrugating shaft, the diameter of which is larger than that of the first corrugating shaft, using a vacuum created inside the second corrugating shaft.

As the second corrugating shaft rotates, the corrugated paper passes through the applicator, where the adhesive is applied to the upper contact portion of the corrugated sheet. In a preferred embodiment, the applicator device comprises a roller having a corrugated surface, generally described above.

The corrugated surface of the glue roller and the corrugated surface of the ND roller (as described above) have a corresponding configuration that allows droplets or a line of adhesive to be applied to the upper contact surface of the crest of the corrugated sheet. This is in contrast to traditional machines, in which the application device usually has a notched surface that allows a relatively wide strip or line of adhesive to be applied to the crest of the corrugation. Therefore, in traditional machines, there is a tendency to apply more adhesive than is necessary, as a result of which this adhesive cannot be completely retained within the upper contact area.

In a preferred embodiment, the clamping mechanism is an endless tension belt.

The endless belt may be configured to allow it to move around a plurality of shafts, and these shafts are arranged so that the belt is pressed against the face layer during the passage of the face layer and the corrugated sheet around the outer surface of the second corrugating shaft.

This arrangement can be achieved by placing two extreme shaft guides at some distance around the outer surface of the second corrugating shaft; the distance between them determines the distance along which the belt is in contact with the front layer. These two extreme guide rollers can be mounted in such a way as to exert pressure (through the belt) on the face layer, first when it is in contact with the corrugated sheet, and then just before the two-layer corrugated sheet comes off the second corrugating shaft.

The belt tension can be adjusted by adjusting one or more of the other shafts so that the belt exerts pressure on the front sheet, pressing it against the corrugated sheet.

Since this process does not require heating, a standard rubber belt can be used instead of the more expensive materials used with heated rollers. The use of a standard rubber belt allows less damage to the surface of the face layer, and therefore, to obtain a better product.

In other embodiments, the endless belt may be made of plastic or synthetic material.

The advantage of this method used at ambient temperature is that the endless belt can be made of heat-sensitive materials, for example, plastic, synthetic materials or some types of rubber, which cannot be used in traditional processes that require heating.

In one preferred embodiment of the invention, the configuration of the endless belt allows holding sheet materials pressed against each other for at least 2 seconds.

In one preferred embodiment of the invention, the configuration of the endless belt allows the sheet materials to be pressed against each other for a period of time from about 2 seconds to about 4 seconds, as described above.

In other words, the present invention makes it possible to efficiently produce two-layer corrugated cardboard without requiring additional heat to be supplied to complete the process.

This feature is achieved by a combination of applying a metered amount of the adhesive to the upper contact portion and then pressing the facing sheet against the corrugated sheet with a predetermined pressure value for a predetermined pressure time until a compound is formed.

In accordance with a further aspect of the invention, there is provided an apparatus for gluing a substantially flat porous sheet material to a corrugated sheet material in a continuous process; wherein the installation contains a large corrugating shaft that engages with a smaller corrugating shaft; the diameter of the smaller shaft is at least in the range between 0.16-0.2 m, and the diameter of the large corrugating shaft is at least in the range of 0.4-2.0 m.

The ability to form two-layer corrugated cardboard at ambient temperature provides one or more of the following advantages over existing methods.

Energy saving and reduced greenhouse gas emissions into the atmosphere compared to traditional methods by eliminating the need for heating the corrugating shafts and drying the paper. This eliminates the need for a high pressure steam, the production of which requires a significant expenditure of energy.

Savings on equipment costs. Since heating is not required, then, accordingly, funds are not required for boilers, pipelines and shells for containing high pressure steam. In addition, since the machine operates at room temperature, it can be made from simpler and cheaper materials, a non-limiting list of which includes ceramics, plastics and wood. Since these materials are generally easier to process and have less weight than materials (usually hardened steel) used in traditional machines using steam, making the machine can be cheaper and its supporting structure can be lighter, which in turn means additional saving on the cost of materials.

Space saving. Removing the equipment required for heating can ultimately allow the installation to take up less space than traditional heated machines.

Increased security. Since the machine operates at room temperature, the danger associated with the production and use of high pressure steam is eliminated.

Saving production costs. In addition to reducing energy consumption, this method can significantly reduce the consumption of adhesive.

An important feature of the installation of the present invention is that it can have dimensions and cost, allowing it to be used for the production of two-layer corrugated cardboard at the place of its use. Traditional heating machines are typically large, consume a lot of energy, and their manufacture and operation are expensive. Therefore, such machines are usually located in centralized places of production, from where the resulting two-layer corrugated cardboard or products made from it are sent to consumers.

The size of the installation of the present invention can be varied, mainly due to the lack of heating equipment. Therefore, the size of the installation of the present invention can be selected acceptable for installation and operation on the territory of the consumer, for example, for the manufacture of packaging on site. This can provide the consumer with cost savings, as the consumer will be able to control inventory, and will not need the funds for transportation and transshipment required in remote production.

In accordance with another aspect of the present invention, an application of the principle of:

RP = DHT / BT

during the construction of a facility for the production of two-layer cardboard;

where RP is the production rate in meters per minute, DHT is the distance in meters over which two corresponding sheets are held pressed together, and BT is the setting time of the adhesive in minutes.

In accordance with another aspect of the present invention, there is provided the use of a water-based adhesive for the manufacture of two-ply cardboard.

In accordance with another aspect of the present invention, there is provided the use of an adhesive, which may be a dispersion containing a vinyl acetate copolymer.

In accordance with another aspect of the present invention, there is provided an apparatus for manufacturing a corrugated sheet of material from a porous flat sheet material by an automated process; the installation contains:

- corrugating shaft;

- fixture in the form of an endless corrugated conveyor belt;

the surface of the endless conveyor belt contains many adjacent corrugations, the configuration of which corresponds to the teeth of the corrugating shaft.

In accordance with another aspect of the present invention, there is provided an apparatus for manufacturing a double layer corrugated sheet of material from a porous material by an automated process; the installation contains:

- corrugating shaft;

- fixture in the form of an endless corrugated conveyor belt; the surface of the endless conveyor belt contains many adjacent corrugations, the configuration of which corresponds to the teeth of the corrugating shaft;

- a clamping mechanism, the configuration of which allows you to hold the freshly made corrugated sheet material pressed to the corrugated surface of the conveyor belt while the adhesive applicator applies the adhesive substance;

- a device in the form of an endless tension belt holding the flat sheet material and the corrugated sheet material pressed against each other for the duration of the formation of the connection between them.

It will be understood by a person skilled in the art that, in addition to replacing a large corrugating shaft with an endless corrugated conveyor belt, most, if not all of the features and aspects described previously when considering the present invention are equally applicable to this linear endless plate conveyor. The exception is aspects inherent only to a large corrugating shaft. For example, production speed, predetermined pressing time, adhesives, suitable porous sheet materials - all this refers to the specified linear device.

The surfaces of an endless grooved conveyor can be shaped into various shapes without departing from the scope of the present invention.

In one preferred embodiment of the present invention, the surface of the endless corrugated conveyor belt may be formed of a plurality of articulated strips of rigid material having a corrugated (corrugated) edge or surface.

In some preferred embodiments, the strip may be in the form of a plate.

In still some preferred embodiments of the invention, the strip may be a bar with a rectangular cross section.

At the opposite ends (with respect to the intended direction of movement along the conveyor) of each of these bars or plates there are connecting sections that make it possible to connect adjacent strips by articulation, forming an endless corrugated conveyor belt.

In another preferred embodiment, the surface of the endless grooved conveyor may be in the form of an endless belt. In some of these embodiments, the tape may comprise a flexible base layer and a corrugated rigid outer layer; the configuration of the outer layer allows you to move around the shafts that make up part of the conveyor device.

The surface of an endless grooved conveyor can be made of various materials without departing from the scope of the present invention.

In one preferred embodiment, the bars / plates are made of steel.

In other embodiments, the bars / plates may be made of plastic, wood, or composite materials.

In a further preferred embodiment, the bars / plates may be made of Plexiglass.

The teeth of the corrugating unit and the corrugations on an endless conveyor can be selected with different profiles without violating the scope of the present invention, provided that the shape of these corrugations allows them to mesh with the teeth of the corrugating shaft. For example, the tooth profile on the roller may take any of the forms: A, B, C, D, E, F or G.

In one preferred embodiment of the invention, the teeth / corrugations may be formed by V-grooves.

In some preferred embodiments of the invention, the surface of the endless conveyor may comprise a series of holes extending from the top to the bottom surface and located generally along the entire length of the surface of the endless conveyor. The function of these holes is to provide a vacuum to the corrugated sheet material to hold it on the corrugations of the surface of the endless conveyor.

In one preferred embodiment of the invention, these holes can be made in the form of slots arranged staggered along the entire surface of the endless conveyor.

The shapes of the pressure mechanism can be varied without departing from the scope of the present invention.

In those embodiments of the invention where the plates do not have the above openings, the clamping mechanism may be in the form of two or more elongated fingers passing through the radial grooves in the corrugating shaft and in the glue roller. Alternatively, the corrugating shaft and the glue roller may be assembled from sections with gaps between sections in which these fingers can be located. The fingers are attached to the spring-loaded device, so that the fingers are able to hold the corrugated sheet material pressed against the plate conveyor.

In preferred embodiments of the invention, the clamping mechanism may be in the form of a vacuum chamber located inside the plate conveyor and having a configuration that allows the vacuum to be supplied to the plates as they pass through the vacuum chamber.

The configuration of the endless conveyor belt may be one that allows it to move around a plurality of rollers and is well known in the art. The rollers are arranged in such a way that the tape is held in contact with the front sheet as the front and corrugated sheets move around the outer surface of the corrugated endless conveyor belt, which functions as the second corrugating shaft.

A corrugated endless conveyor belt formed from a plurality of adjacent plates can be configured in various ways without departing from the scope of the present invention.

In a preferred embodiment, the plate conveyor may comprise one or more flexible tapes to which the plates are attached. These tapes move around the rollers under the influence of a drive mechanism, as is known in the art.

The glue applicator can take various forms.

The adhesive applicator may preferably be a corrugated adhesive roller that engages (presses) with the teeth of the plates. The glue roller receives glue from the glue picking roller and the glue tray associated with it.

However, other configurations generally described above may also be imparted to the glue applicator.

In accordance with another aspect of the present invention, there is provided an apparatus for manufacturing a three-layer corrugated board in a continuous automated process; the installation contains:

i) installation module for the manufacture of two-layer corrugated cardboard, containing:

- corrugating shaft;

- an endless corrugated belt conveyor having an endless corrugated conveyor surface containing a plurality of corrugations adjacent to each other; while the corrugations have a configuration corresponding to the teeth of the corrugating shaft;

the module has such a configuration that the sheet material passing between the respective engaging teeth of the corrugating shaft and the endless corrugated belt conveyor becomes corrugated and held by the first clamping mechanism until it contacts the adhesive application device and makes contact with the flat sheet material and the second clamping mechanism in the shape of an endless tension belt that holds the corresponding flat and corrugated sheets pressed against each other to form a joint between them;

ii) a laminating module comprising:

- two linear devices located vertically opposite each other, having the form of endless tension belts, taking into space among themselves:

a) flat sheet material; and

b) a two-layer corrugated sheet material obtained from the module of the corrugating unit;

wherein the adhesive applicator applies the adhesive to the two-layer corrugated cardboard and / or to the flat sheet material until they are inserted into opposite endless tension belts holding the flat sheet material and the two-layer corrugated cardboard pressed against each other to form a joint between them.

In accordance with another aspect of the present invention, there is provided a gluing method for use in the manufacture of a porous two-layer or three-layer corrugated cardboard, characterized by the step of applying at least one device in the form of a linear tension belt and one device in the form of an endless corrugated conveyor for holding corrugated sheet material and flat sheet material pressed against each other to form a connection between them.

In accordance with another aspect of the present invention, there is provided a method, generally described above, in which corrugated sheet material and flat sheet material are held pressed against each other during a pressing period calculated by the formula:

BT = DHT / RP,

where RP is the production speed in meters per minute, DHT is the distance in meters over which two corresponding sheets are held pressed together, and BT is the setting time of the applied adhesive in minutes, and this value determines the pressing period.

In accordance with another aspect of the present invention, there is provided a two-ply cardboard made using the method generally described above.

In accordance with another aspect of the present invention, there is provided a three-ply cardboard made using the method generally described above.

In accordance with a further aspect of the present invention, there is provided a three-ply cardboard made from a two-ply cardboard using the method generally described above.

In accordance with another aspect of the present invention, there is provided a two-ply cardboard made of a flat sheet with pre-printed material glued directly to the corrugated sheet material at ambient temperature.

In accordance with another aspect of the present invention, there is provided a three-layer cardboard with pre-printed material made by gluing a flat sheet with pre-printed material directly to a corrugated sheet material that is part of a two-layer cardboard made at ambient temperature.

In a preferred embodiment, a flat sheet with pre-printed material is glued to the two-layer cardboard immediately after its formation in a continuous automated in-line process.

In accordance with another aspect of the present invention, there is provided a three-layer board made by gluing two flat sheets with pre-printed materials directly to the lower and upper surfaces of the corrugated sheet material at ambient temperature.

It is obvious that flat sheets with the material printed on them are glued to the corrugated sheet material in such a way that the printed surface (s) becomes (become) the outer surface (s) of the two-layer / three-layer cardboard.

The use of preferred embodiments of the device in the form of an endless linear tension belt and an endless plate conveyor belt can provide the following advantages:

providing a method for increasing the production rate according to the formula: RP = DHT / BT, where RP is the production rate in meters per minute, DHT is the distance in meters over which two corresponding sheets are held pressed against each other, and BT is the setting time in minutes.

In particular, the production rate is not limited by factor X, as in non-linear corrugating plants (i.e., having large and small corrugating shafts engaged with each other) with dimensions determined by the formula C = (RP.BT) / X, where C is the circumference of the larger shaft (i.e., π2r), RP is the production rate in meters per minute, BT is the setting time of the applied adhesive in minutes, and X is the percentage of the circumference to which pressure is applied side endless tension belt. This formula is derived from the fact that DHT equals X (π2r). The maximum value of X for a large corrugating shaft is a speed limiting factor, since the diameter of a large corrugating shaft cannot significantly exceed 2 meters due to the fact that in this case it will be incredibly heavy. In contrast, the length of the linear corrugating device can be easily and practically unlimitedly extended if necessary.

Providing the above advantages of the cold process over traditional technology for the production of not only two-layer, but also three-layer corrugated cardboard.

Preferred embodiments of the present invention using both linear and non-linear corrugating devices also provide the following advantages:

the ability to glue paper with pre-printed material directly on corrugated cardboard during a continuous automated in-line process;

the ability to produce two-layer or three-layer corrugated cardboard that looks perfectly flat for the naked eye and does not tend to bend corners, due to the fact that during its manufacture there is no heating, and a passive braking system for paper unwinding from a roll.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present invention will become apparent from the following description, presented by way of example only with reference to the accompanying drawings, wherein:

in FIG. 1A and 1B show the upper contact portion in a schematic side view of the corrugated sheet before and after gluing it to the facing sheet;

in FIG. 2 is a schematic perspective view of a part of a two-layer cardboard manufacturing apparatus according to one of the preferred embodiments of the present invention;

in FIG. 3 is a perspective view of a double-layer board manufacturing apparatus of FIG. 2;

in FIG. 4 is a schematic perspective view of a part of a two-layer cardboard manufacturing apparatus according to yet another preferred embodiment of the present invention;

in FIG. 5 is a schematic perspective view of a linear corrugating unit for manufacturing a two-layer corrugated board according to one preferred embodiment of the following aspect of the present invention; and

in FIG. 6 is a schematic perspective view of a three-layer corrugated board manufacturing apparatus according to one of the preferred embodiments of the next aspect of the present invention, in which the linear corrugating assembly of FIG. 6.

In FIG. 7 shows a top view of a cylindrical rod described in detail in the embodiment shown in FIG. 2.

In FIG. 8 is a plan view of the centering rod described in detail in the embodiment shown in FIG. 2.

In FIG. 9 is a plan view of a convex roller that is part of an endless tension belt device described in detail in the embodiment shown in the embodiment of FIG. 2.

In FIG. 10 is a schematic perspective view of a three-layer corrugated board manufacturing apparatus according to one of the preferred embodiments of the next aspect of the present invention, which employs a linear corrugation unit modified from that shown in FIG. 6.

In FIG. 11 shows a surface section of an endless conveyor in the form of a conveyor belt consisting of many strips in the form of corrugated bars.

In FIG. 12 is a side view of a corrugated bar which is a part of the conveyor belt of FIG. eleven.

In FIG. 13 shows a cross section of the corrugated bar of FIG. 12.

In FIG. 14 is a perspective view of the corrugated bar of FIG. 12.

BEST MODE FOR CARRYING OUT THE INVENTION

In FIG. 1A and 1B schematically depict a corrugated (corrugated) sheet of paper (100), which shows the upper contact portion (101).

The upper contact area includes the top (102) of the ridges (103), as well as the area on each side that adheres with the applied adhesive (104) to the face sheet (105).

In FIG. Figures 2 and 3 show a part of an apparatus for manufacturing a two-layer corrugated cardboard, known as an aggregate for the production of a two-layer corrugated cardboard, and generally indicated by an arrow (200). In the unit for the production of two-layer corrugated cardboard (200) there is a first (smaller) corrugating shaft (201) and a second (large) corrugating shaft (202). It should be noted for clarity that in this image the shafts (201, 202) are not shown completely, but are assembled from a sequence of shaft parts mounted next to each other on an axis (not shown) until a shaft of the desired length is obtained.

In the process, the porous sheet material in the form of kraft paper (250) is supplied to the corrugating shafts (201) and (202). After passing through the shafts (201, 202), the kraft paper (250) becomes a corrugated (corrugated) sheet material (251).

On the second shaft (202) there are teeth (203), which are in contact with the transverse grooves (204) on the surface of the glue-applying (NK) roller (205). The surface of the adhesive-applying roller (205) collects an adhesive in the form of Adhesin ™ Z9040 from an adhesive bath (not shown), and excess adhesive is removed from the surface with a scraper (206) so that the adhesive remains only in the grooves (204). In use, the newly formed corrugated sheet material (251), pressed against the second shaft (202) by vacuum, extends between the second shaft (202) and the glue roller (205) so that the upper contact portion (not shown) of the corrugated sheet material enters the grooves (204) together with the teeth (203), whereby the adhesive is transferred to the upper contact portion.

At this point, a flat (facing) sheet material (260) in the form of kraft paper is fed between the tensioner (270) with an endless belt and the second corrugating shaft (202) and pressed against the upper contact portions of the corrugated sheet material (251). The tensioner has an endless tension belt (271) that applies a predetermined pressure to the flat sheet (260) while holding it pressed against the corrugated sheet (251). An endless belt (271) applies a predetermined pressure to 76% of the circumference of the large shaft (20), as shown by arrow X. Those skilled in the art will understand that in some embodiments, the sheet material (260) can be pre-printed with high quality graphic images and / or text.

The endless tension belt has a number of rollers (290-294), the tension is set by adjusting the position of the tension roller (292) with respect to the axis of the second large corrugating shaft (202). During operation, the tension of the belt (271) is first set to a value that causes damage to the face and / or corrugated paper, which usually appears as folds or tears. Then, the tension is loosened, gradually returning the tension roller (292) to the point where the face / corrugated paper is no longer damaged (i.e., the tension roller is set back to the set pressure).

The corresponding sheets (260, 251) are held pressed together for a predetermined period of time defined by the formula:

BT = DHT / RP,

where RP is the production rate in meters per minute, DHT is the distance in meters over which two corresponding sheets are held pressed together, and BT is the setting time in minutes. Thus, it can be seen that the percentage of 360 ° indicated by the double-sided arrow X, where the endless tension belt contacts the shaft circumference (20), is critical for determining the distance at which the sheets are held pressed against each other, and, consequently, the production speed .

The circumference of the second corrugating shaft (202) is determined by the formula:

C = (RP.BT) / X,

where C is the shaft circumference (i.e. π2r), RP is the production speed in meters per minute, BT is the setting time in minutes, and X is the percentage of the circumference to which pressure is applied from the endless tension belt .

Thus, if a production speed of 44 m / min is required, and the setting time of the adhesive is 2 s (i.e., 0.0333 min.), Then the circumference of the second shaft is 44 × 0.0333, which equals; 1.4666 divided by 76%, resulting in 1.93 m. This means that the diameter should be 0.62 m. In other words, in this example, DHT is equal to the product of 2πr by 0.76%.

The kraft paper used in the process is recycled paper or primary paper, preferably with a density of about 90-150 g / m ² .

In the second corrugating shaft (202) there is a network of channels (not shown) leading from a vacuum pump (not shown) to the shaft surface (not shown) through which the vacuum pump creates a low vacuum inside the second corrugating shaft (202). This low vacuum inside the second corrugating shaft (202) keeps the corrugated sheet (260) in position on the teeth (203) of the second corrugating shaft (203).

In FIG. 2 also shows that in the corrugating unit (200) there are first and second guide systems as a whole indicated by arrows (500) and (502).

In the first guide system (500), there are three cylindrical rods (510-512) defining a zigzag path of paper (250) exiting the roll (not shown). The guide system provides a straight line of paper (250) as it is unwound from the roll and fed into the machine (200). These cylindrical rods (510-512) do not rotate, but apply a friction force, forcing the paper to move in a straight line, and prevent any movement deviation to the left or right as it leaves the roll. An additional guiding effect facilitating the work with paper of cylindrical rods (510-512) is exerted by their end flanges (513) (see Fig. 7), which prevent the paper from sliding off the rods and violating its alignment with the corrugating unit (200).

In the second guide system (502) there is a first guide rod (520), at the ends of which there are sockets (525) (see Fig. 8), conically extending from the cylindrical central section of the rod, which is the width of the paper (260) exiting the roll (not shown). The bells extend approximately 50 mm from the edges of the paper (260) extending along the shaft (520). Then, paper (260) passes around a cylindrical rod (521) having flange ends (see Fig. 7). Then the paper (260) passes to the second guide rod (522) having sockets at the ends (see Fig. 8). These rods (520, 521 and 522) are also stationary, as are the rods of the first guide system (500).

Prior to feeding into the machine (200), paper (260) passes through the roller (290) of the tensioner (270) with an endless belt. This roller (290) has a convex outer surface (see Fig. 9). The inventor has found that the convex outer surface of this roller minimizes the risk of the paper being pulled into the center and wrinkling before being fed into the machine (200). This contraction occurs as a result of the fact that the second guide rod (522), the end sockets of which prevent the paper from tilting to the right or left when passing through this rod (522), directs the paper to the center.

Qualified specialists in this field will understand that the relative position of the rods with respect to each other and to the corresponding rollers in the first and second guide systems (500) and (502) can be adjusted so that the desired pressure is applied to the paper, holding it in alignment position with installation (200).

During operation, the tensioner (270) with an infinite tension belt through the belt (271) applies pressure to the front (260) and corrugated paper (251) (which was originally Kraft paper 250) during their passage along 76% of the shaft circumference (203 ), as shown by arrow X: until the double-layer corrugated cardboard (280) is formed and exits the installation (200).

It will be understood by those skilled in the art that embodiments of the invention with larger and smaller engaging corrugating shafts, such as those shown in FIG. 2, 3 and 4, can also be used for the manufacture of three-layer corrugated cardboard. For the implementation of this process, the equipment also includes an installation for the manufacture of three-layer cardboard (not shown), well known in this field.

It is understood, although not shown, that in the embodiments of the invention shown in FIG. 4, 5 and 6, guide systems for paper exiting the rolls are also involved. The guide systems may be substantially the same as those discussed in detail in FIG. 2.

In FIG. 4 shows a setup similar to that shown in FIG. 2 and 3, and therefore similar elements are denoted by like reference numerals. The key differences of the embodiment of FIG. 4 consist in that the radius of the large corrugating shaft (202) is 1 m and the diameter of the large corrugating shaft (202) shown in FIG. 2 and 3, is 2 m, and the endless belt (271) applies pressure to approximately 93% of the circumference of the large shaft (202), as shown by arrow X.

In FIG. 5 shows an apparatus for manufacturing a two-layer corrugated sheet material having the form of a linear corrugating assembly, generally shown by arrow (300). This unit (300) comprises an endless corrugated conveyor surface in the form of an endless plate conveyor belt (301) having a plurality of adjacent corrugated plates (302) attached to a pair of flexible endless belts (not shown), which is driven by a drive a mechanism having an engine (not shown) and a pair of pinion gears (303). The endless belt conveyor contains a series of idle rollers (304) holding the endless conveyor belt (not shown) and plates (302) on the lower surface at a fixed height relative to the endless tension belt (350). The drive mechanism and rollers of the endless tension belt (350) are not shown, since their arrangement is well known in the art.

The endless plate conveyor (301) has a vacuum pump (305) capable of applying vacuum to a freshly made corrugated sheet material in the form of kraft paper (not shown) that has just passed between the corrugating shaft (306) and the endless plate conveyor (301) . Holes in the form of cutouts (307) in the plates (302) allow the vacuum to act on the corrugated kraft paper.

After the corrugated kraft paper leaves the corrugating shaft (306), a metered amount of the adhesive (not shown) is applied to the upper contact areas (not shown) on the ridges (not shown) using an adhesive roller (308) having a corrugated surface (not shown) . It should be understood that this glue roller (308) may be the same as described and suitable for use in the embodiments of the invention shown in FIG. 2, 3, and 4. Adhesive is collected from an adhesive tray (not shown) by an adhesive picking roller (308) and transferred to the adhesive roller (309).

A preferred configuration of the adhesive roller (308) may allow it to be moved in the transverse direction with respect to the tension belt device (310), which makes it possible to adjust the position of the roller for smaller paper widths. A flat sheet of material in the form of a front sheet of kraft paper (not shown) is fed between the plate conveyor (301) and the endless tension belt (350) at the point indicated by the arrow (310). The length (i.e., the distance) over which the plate conveyor (301) and the endless tension belt (350) overlap each other is the DHT value.

It is easy to understand that the length of both the endless conveyor belt (301) and the endless tension belt (350) can be increased in order to increase the production speed according to the formula:

RP = DHT / BT.

In FIG. Figure 6 shows part of an apparatus for manufacturing a three-layer corrugated sheet material, generally indicated by arrow (400). In this installation (400) there is a module for manufacturing a two-layer corrugated material having the form of a linear corrugating unit (401), which is almost similar to that described above when considering FIG. 5. As shown, kraft paper (402), intended for corrugation, enters the linear corrugating unit (401), and kraft paper (403), which will form the front layer, enters the linear corrugating unit after the adhesive rollers (407) . Above the linear corrugating unit (401), there is a laminating module, which is a corrugating unit for the manufacture of a three-layer cardboard (404). This corrugating unit for the manufacture of three-layer cardboard (404) has two endless tension belts (405, 406) located opposite each other and a device of an adhesive roller and a pressure roller (407) through which a two-layer corrugated cardboard passes before being fed into the corrugating unit for the manufacture of a three-layer cardboard (404). The glue roll assembly (407) is substantially the same as that described in conjunction with FIG. 5. Kraft paper (408), which forms the front layer of the three-layer cardboard, enters the unit (400) and moves upward along the endless plate conveyor (410) of the linear corrugating unit (401) before it enters the corrugating unit for the manufacture of a three-layer cardboard ( 404) together with two-layer corrugated cardboard at the point shown by the arrow (409).

Qualified specialists in this field will understand that on a flat sheet material used in the embodiments of the invention shown in FIG. 5 and 6, in some embodiments, high-quality graphic images and / or text can be pre-printed. For example, on the flat sheet material (403) and (408) shown in FIG. 6, there may be pre-printed material.

In FIG. 10 shows a part of an apparatus for manufacturing a three-layer corrugated sheet material, generally indicated by an arrow (1000). This installation (1000) contains a module for manufacturing a two-layer corrugated cardboard in the form of a linear corrugating unit (1001), generally described in connection with FIG. 5. Above this linear corrugating unit (1001) is a laminating module in the form of a corrugating unit for the manufacture of a three-layer cardboard (1004). This corrugating unit for the manufacture of three-layer cardboard (1004) has two endless tension belts (1005, 1006) located opposite each other, as well as a node in the form of an adhesive roller and a pressure roller (1007), through which a two-layer corrugated cardboard (not shown) passes, made by linear corrugating aggregates (1001), before being fed into the corrugating aggregate for the manufacture of a three-layer cardboard (1004). The glue roll assembly (1007) is substantially the same as that described in conjunction with FIG. 5. Kraft paper (not shown), which forms the front layer of a three-layer cardboard, enters the unit (1000) and moves on top of the corrugated surface of the endless conveyor (1010) of the linear corrugating unit (1001) until it is fed into the corrugating unit for the manufacture of a three-layer cardboard ( 1004) together with two-layer corrugated cardboard at the point shown by the arrow (1009).

One distinguishing feature of the apparatus shown in FIG. 10 with respect to those described in connection with FIG. 5 and 6, relates to the shape of a conveyor of a linear corrugating unit (1001). The surface (1010) of the endless conveyor is formed by corrugated bars (1011) shown in FIG. 11, in contrast to the corrugated plates shown in FIG. 5 arranged in the same way to form an endless ribbon. Corrugated bars (1011) have connecting portions representing a pair of holes (1012) at each end of the rod into which studs (not shown) can be inserted to connect adjacent bars (1011) to each other to form a tape (1010). These grooved bars (1011) are shown in more detail in FIG. 12-14, and in particular, a corrugated upper surface (1012) of the bar (1011) is shown.

In the linear corrugating unit (1001), there is a belt (1010), which the corrugating shaft (1020) rotates (using a motor that is not shown), thus the teeth of the shaft (1021) engage with the corrugations (1012) of the bars (1011), moving the tape (1010). In addition, additional force for the movement of the belt can be applied by driving gears (1015) rotating from a separate motor (not shown) so that the teeth (1016) of the gears can engage with the connecting rods of the rods (1011) through the gaps (1017) between adjacent bars (1011) tapes (1010). These gaps (1017) also help to supply vacuum through the conveyor in the same way as described above with reference to FIG. 5.

Example 1

To calculate the production speed of a plant with a second corrugating (i.e. large) shaft 1.6 m in diameter, in which an endless belt covers 76% of the circumference of the second shaft, substituting these values in the new formula of the present invention RP = DHT / BT, we obtain the value RP (production speed) equal to 0.76 (π1.6) / 0.05, which is the production speed equal to 76 m / min., While 0.05 minutes is the setting time of 3 seconds. This production rate is significantly lower than that calculated by the applicant in WO 2009/000085.

Example 2

If the manufacturer requires a production speed of 143 m / min. using an adhesive having a BT value of 0.033333 min. (i.e., 2 s), then the diameter of the second corrugating (i.e., larger) shaft, applying the new formula of the present invention, DHT, can be represented as 0.93 × (π2r), and the diameter can be calculated as follows: DHT = RP.BT, which is (143 × 0.033333). Then, to get the diameter, we rewrite the equation as follows: 0.93 × (π2r) = (143 × 0.033333), whence 2r (i.e. diameter) = ((143 × 0.033333) / 0.76) / π, that is, this diameter will be 2 m.

Example 3

Suppose you want to calculate the production speed of a plant with a shaft of 2 m in diameter, with a VT value of 0.05 minutes. (i.e. 3 s). Applying the indicated formula, we obtain RP = DHT / BT 0.93 (π2) / 0.05, which equals 116 m / min.

In practice, a value of 2 m is the limit or close to the limit value of the diameter of the shaft for the production of corrugated board using a pair of corrugating shafts engaged with each other, as described here, as shown in FIG. 2 or as described in a previous PCT application WO 2009/145642 of the same applicant. One of the reasons why in practice it is impossible to use a large corrugating shaft with a diameter significantly greater than 2 m (for example, 2.5 m, 3 m or more) is because the weight of such a shaft will be too large to be able to lift and move, especially during manufacturing, maintenance or repair. In addition, the increased weight of the shaft with a diameter exceeding 2 m, will require significantly more energy to rotate the shaft, and, consequently, will increase production costs. In addition, there are problems with creating a vacuum inside such a large shaft and, again, it requires more energy. The applicant believes that an increase in production speed due to an increase in the diameter of a large corrugating shaft with a diameter of more than 2 m will not be able to outweigh the negative effect of the above problems.

Example 4

A non-linear corrugating assembly similar to that shown in FIG. 4, is capable of producing two-layer corrugated cardboard at a faster rate than in the above examples, even with the same setting time of the adhesive. For example, to get a production speed of 200 m / min. with a BT value of 0.033333 minutes, an endless plate conveyor, covered by an endless tension belt over a length of 6.6 m, is required. The corresponding formula is RP = DHT / BT.

The described aspects of the present invention are presented only as an example, it is understood that they can make changes and additions, without going beyond the scope of the appended claims.

Claims (3)

1. The module for the manufacture of a two-layer corrugated sheet of porous material in an automated process, while this module includes:
- corrugating shaft;
- a corrugated roller for applying discrete drops of glue to the ridges of a freshly made corrugated sheet material, wherein the corrugated roller includes a corrugated surface where the protrusions and grooves of the corrugations are made either in the form of concentric circles or in the form of a spiral;
- node endless corrugated belt conveyor having an endless corrugated surface of the conveyor containing many adjacent corrugations, while the corrugations have a configuration corresponding to the teeth of the corrugating shaft;
- a clamping mechanism configured to hold a freshly made corrugated sheet material on a corrugated conveyor surface during application of glue by a corrugated roller;
- an endless tension belt assembly located under the endless corrugated belt conveyor and holding the flat sheet material and the two-layer corrugated cardboard together, so that the corrugated material remains placed opposite the endless corrugated conveyor until a connection is formed between them, while the clamping mechanism is made in the form of a vacuum chamber. 2. Installation for the manufacture of three-layer corrugated cardboard in an automated process, which includes a module for the manufacture of a two-layer corrugated sheet according to claim 1, while this installation also includes:
i) a laminating module located above the specified module for the manufacture of a two-layer corrugated sheet, containing:
- two endless tension belts located vertically opposite each other, between which include:
a) flat sheet material; and
b) a single layer corrugated sheet material obtained from a corrugating module,
wherein the adhesive applicator is made in the form of a corrugated roller, which includes a corrugated surface, where the protrusions and grooves of the corrugations are made either in the form of concentric circles or in the form of a spiral, and the corrugated roller applies discrete drops of glue to the ridges on a single-layer corrugated cardboard before being fed into opposite endless tension belts holding flat sheet material and single-layer corrugated cardboard pressed against each other to form a connection between them. 3. The method of connection, intended for use in the manufacture of two-layer or three-layer corrugated cardboard, characterized by the stage of application of the device in the form of at least one infinite linear tension belt and one infinite plate conveyor to hold the corrugated sheet material and flat sheet material pressed against each other to form the connection between them, while the specified pressing time, during which the corrugated sheet material and flat sheet m The atrial is held pressed to each other, calculated by the formula:
BT = DHT / RP,
where RP is the production speed in meters per minute, DHT is the distance in meters over which two corresponding sheets are held pressed against each other, and BT is the glue setting time in minutes, and this value determines the pressing time.

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