EP0597840B1

EP0597840B1 - Corrugated board manufacture

Info

Publication number: EP0597840B1
Application number: EP91909478A
Authority: EP
Inventors: Michael John 2 Sir William Lyons Road Cahill; Colin Stutt
Original assignee: Langston Machine Co Ltd
Current assignee: Langston Machine Co Ltd
Priority date: 1990-05-15
Filing date: 1991-05-14
Publication date: 1998-07-22
Anticipated expiration: 2011-05-14
Also published as: AU7874191A; AU664018B2; JPH05506825A; DE69129863D1; WO1991017881A1; DE69129863T2; NZ238143A; EP0597840A1

Abstract

The invention concerns a process for manufacturing corrugated board comprising two layers of corrugated medium joined together in tip-to-tip registration between the corrugations of the two mediums, without an intermediate liner, and with at least one outer liner, the process comprising feeding webs (7) of corrugating material between respective pairs of corrugating rolls (4, 5) to form the webs into corrugated mediums, applying adhesive (32, 33) to the tips of one of the mediums to permit adhesion with the tips of the other medium, and conveying the two mediums along adjacent linear paths (23, 24) with tip-to-tip registration between the corrugations of the two mediums, while applying pressure urging the mediums into contact with one another while the adhesive is caused or allowed to set at least partially, at least one outer liner (11) being applied either before or after the corrugated mediums are conveyed along the linear paths in which the tips of their corrugations are brought together.

Description

This invention is concerned with the manufacture of corrugated board comprising two layers of corrugated medium adhering to one another, with no intermediate liner, and at least one liner adhering to the outer tips of one of the two corrugated mediums. Board of this type is described and illustrated in Australian patent applications Nos. 62323/86 and 2271/85, and a machine for manufacturing such board is described in European patent application No. 279609, all in the name of Amcor Limited. A further development of the machine is described in our British patent application No. PCT/GB 89/01290, to which reference is directed.

It is important to achieve accurate tip-to-tip registration between the corrugations of the two mediums and reliable adhesion between the tips. A proposal for achieving this is described in European patent application No. 321247, which involves conveying the corrugated mediums together along linear paths. However, that proposal involves pressing the mediums only at the moment at which one medium is applied to the other at the beginning of the linear movement of the two mediums. Accordingly, in that brief moment sufficient adhesion between the corrugated mediums must be established to achieve tip-to-tip registration of the final produce.

In contrast with the proposal described in European patent application No. 321247, the present invention achieves accurate and reliable tip-to-tip registration of the mediums by conveying them together between linear conveyors which press the tips of the two mediums together while the adhesive joining the mediums is being caused or allowed to set at least partially.

According to the present invention, a process for manufacturing corrugated board comprising two layers of corrugated medium joined together with tip-to-tip registration between the corrugations of the two mediums, without an intermediate liner, and with at least one outer liner, comprises separately and identically corrugating two webs of corrugating material, applying adhesive to the tips of one of the mediums to permit adhesion with the tips of the other medium, bringing the two mediums together with tip-to-tip registration and from then on conveying them along adjacent linear paths with tip-to-tip registration between the corrugations of the two mediums while the adhesive is caused or allowed to set at least partially, at least one outer liner being applied either before or after the corrugated mediums are conveyed along the linear paths in which the tips of their corrugations are secured together, whereby the corrugating mediums are corrugated by being passed between separate pairs of corrugating rolls and that, after leaving the corrugating rolls, upon being brought together at the beginning of their linear paths, they are pressed together by pressing the tips of the two mediums into contact with one another while the adhesive is being caused or allowed to set at least partially, characterized in that pressure is additionally applied by opposed linear conveyors.

According to another aspect of the present invention, apparatus for carrying out the above process may comprise means for forming two single-faced webs each comprising a corrugated medium attached to a liner, means for applying adhesive to the tips of one of the corrugated mediums, and means for bringing the corrugated mediums into contact with one another and for then conveying the two mediums along linear paths with tip-to-tip registration between their corrugations while the adhesive is being caused or allowed to set at least partially, characterised by opposed linear conveyors which apply pressure to the mediums urging them together while they are moving along the linear paths.

Apparatus for carrying out the above process may alternatively comprise means for separately corrugating the two webs of corrugating medium, means for applying adhesive to the tips of one corrugated medium, and means for bringing the corrugated mediums together and for then conveying them along adjacent linear paths with tip-to-tip registration while the adhesive is being caused or allowed to set at least partially, and including means for applying at least one outer liner to the joined corrugated mediums, characterised by opposed linear conveyors which apply pressure to the two corrugated mediums urging them together while they are moving along the linear paths.

Examples of apparatus according to this invention will now be described with reference to the accompanying drawings. In these drawings:

Figure 1 is a diagrammatic elevation of part of one apparatus according to this invention;

Figure 2 illustrates diagrammatically a modification in the region of the pressure device;

Figure 3 is a diagrammatic elevation of another apparatus according to this invention;

Figure 4 is a perspective view of one of the rolls in the apparatus shown in Figure 3; and

Figure 5 shows a modification of the right hand end portion of the apparatus shown in Figure 3.

As shown in Figure 1, one single-faced corrugated web 2 is formed by a single-facer machine 3 comprising heated upper and lower corrugating rolls 4 and 5 and a heated press roll 6. A web 7 of corrugating medium passes around a pre-conditioner guide 8 by which it is moistened prior to entry into the nip between the corrugating rolls 4 and 5. A gluing device comprising a metering roll 9 and an applicator roll 10 applies glue to the tips of the corrugated medium to cause adhesion with a liner web 11 conveyed around the press roll 6, thus forming a single-faced corrugated web 2 in which the corrugated medium lies above the liner. An infrared heater 12 applies more heat to the web as it passes towards a pressure device indicated generally by the reference numeral 13.

A similar single-facer machine (not shown), effectively a mirror image of the single facer machine 3 mounted above the machine 3 and slightly further to the left, forms a second single-faced corrugated web 19 of which the corrugated medium lies below the liner.

The single-faced web 2 passes towards the pressure device 13 via a tensioning roll 14 which is movable up and down so as to form a loop of variable lengths between

guide rolls

15 and 16. The roll 14 may be of lightweight construction, being in contact with the corrugated material, or may be mounted at its opposite ends on two pivoted levers with counter balance weights so that it applies a limited force to the web 2.

Similarly, an upwardly urged tensioning roll 17 tensions and produces a path of variable length for the second single-faced corrugated web 18.

Corrugated register rolls

19 and 20 associated with the pressure device 13 engage in corrugations of the

respective webs

2 and 18 and control the movement of the webs beyond the tensioning devices. The webs pass around the register rolls and around

lead rolls

21 and 22 and then converge towards parallel paths extending between sets of upper and

lower belts

23 and 24 arranged in upper and lower pairs. These belts are driven by

drive rolls

25 and 26 and are tensioned by

rolls

27 and 28. The lower belts 24 are supported by a platen 29 having grooves of just sufficient depth to accommodate the belts, the lands between the grooves being at a level such as to support the lower web 2 during its passage through the pressure device.

An air pressure chamber 30 urges the upper single faced corrugated web 18 downwards on to the lower web to cause adhesion between the tips of the corrugated medium, adhesive having been applied to the upper corrugated medium by a device comprising a metering roll 32 and an applicator roll 33. In addition, or as an alternative, pads formed by flexible bristles may be arranged to press down on the upper web in areas lying between the upper belts, one such bristle being shown for example at 34.

The register rolls are driven by separate motors which are electronically timed with respect to one another to ensure that the flute alignment occurs between the two webs. This timing is achieved with the aid of

flute count encoders

35 and 36. Similar encoders are mounted adjacent to the exposed portion of the middle roll of each single-facer machine; Figure 1 shows such an encoder 37 adjacent to the corrugator roll 5 of the lower single-facer 3.

By means of the

flute count encoders

35 and 37, for example, a drive motor for the lower single-facer machine is controlled as to its speed so as to maintain an appropriate web speed. This control need not be as accurate as the control between the two register rolls. Means (not shown) are provided for detecting when the tension roll 14 moves upwards beyond a desired upper limit, whereupon the speed of the drive to the single-facer 3 is increased, movement of the tension roll 14 below a desired lower limit being similarly arranged to reduce the speed of the drive to the single-facer 3. A similar control exists between the register roll 20 and the upper single-facer machine.

After leaving the pressure device 13, the double-faced web 50 may pass through a conventional double-facer arrangement (not shown) for applying pressure, pneumatically or by means of weighted conveyors, to opposite faces of the web 50 over a more extended distance while the adhesive fully sets.

The gap between the

conveyor bands

23 and 24 of the pressure device may be adjustable so that, for example, conventional double-faced board (with just one corrugated medium) can be manufactured by feeding a simple liner in place of the single-faced web 18. Another permutation made possible by this apparatus is that a third liner may be fed between the two single-faced corrugated webs to form a "double double" board. To facilitate this possibility, the apparatus may be modified in the region of the pressure device in the manner shown in Figure 2.

As shown in Figure 2, a larger angle of convergence between the two single-

faced webs

2 and 18 is provided to facilitate the conveyance between them of a third liner 37. In addition there is a further adhesive

applicator comprising rolls

38 and 39 for applying adhesive to the tips of the corrugator medium of the lower web 2.

Figures 3 to 5 show a different machine.

Figure 3 shows

webs

101 and 102 of corrugating medium which are corrugated respectively by

corrugating rolls

103, 104 and 105, 106. After being corrugated the webs may be held on the

respective rolls

104 and 105 by suction supplied through radial passages in the rolls from suction chambers 107 and 107'.

The corrugated medium 102 is further conveyed by a roll 108 which cooperates with the roll 104 in bringing together the tips of the respective corrugated mediums. As shown in Figure 4, the roll 108 has a number of circumferential recesses 109 leaving relatively narrow corrugated surfaces 110 for pressing the corrugated mediums 102 against the medium 101. Adhesive is applied to the tips of the corrugations of the medium 101 by an adhesive applicator unit 111.

The corrugated mediums are conveyed beyond the

rolls

108 and 104 initially by conveyor belts 112 which are accommodated in the circumferential recesses in the roll 108 and are formed with external corrugated surfaces which are maintained in alignment with the roll corrugations by engagement with the corrugations of the roll 105. The belts, which may be in the form of moulded belts or may comprise chains, pass over a heater 113 and return around a roller 114.

Pressure contact between the tips of the corrugations of the two mediums is maintained, during movement along the linear path between the

rolls

108 and 114, with the aid of a further set of corrugated conveyor belts 115 passing around

rolls

116 and 117. The belts 115 are maintained in appropriate timed relation to the belts 112; for example, the belts 115 may have internal timing teeth meshing with teeth on the roll 116, which may in turn be driven from, for example, the roll 108 via gears or a timing belt. A further heater 118 helps to dry the adhesive.

The conveyor belts 112 continue to support the corrugated mediums while adhesive is applied to the tips of the upper medium, by a device 119', prior to the application of a first liner 119. The tips of the lower medium then receive adhesive from a device 120' in preparation for the application of a second liner 120.

Further heaters

121 and 122 apply heat to the complete product, and any suitable known means (not shown) may be used for applying pressure until the adhesive is substantially fully set.

Figure 5 shows an example of another way in which the two outer liners may be applied to the corrugated mediums. The joined corrugated mediums remain on the roller 114, being held by suction from a suction chamber 121, until they are received by a further corrugated roll 122 on which they are held by suction transmitted from a chamber 123. Adhesive is applied to the exposed outer tips of the lower corrugated medium by a device 124, and a liner 125 is then applied to the corrugated mediums, being pressed against them by a heated roll 126. The single-faced corrugated board is then received by a further roll 127 having a smooth circumference, and is held on the roll 127 by suction transmitted from a chamber 128 while adhesive is being applied to the exposed outer tips of the upper corrugated medium by a device 129. A second liner 130 is then applied with the aid of a heated roller 131 so as to form the desired board 132. The board 132 may then pass through any conventional pneumatic or other pressure device for pressing the components of the board together along an extended distance while the adhesive is allowed to fully set.

With reference to Figure 3, quick adhesion between the corrugated mediums may be achieved by applying a quick-setting adhesive to the corrugated medium 101 along bands corresponding to the corrugated positions 110 of the roll 108. Between those bands a slower drying adhesive may be used.

Claims

A process for manufacturing corrugated board comprising two layers of corrugated medium joined together with tip-to-tip registration between the corrugations of the two mediums, without an intermediate liner, and with at least one outer liner, the process comprising separately and identically corrugating two webs (7; 101, 102) of corrugating material, applying adhesive to the tips of one of the mediums to permit adhesion with the tips of the other medium, bringing the two mediums together with tip-to-tip registration and from then on conveying them along adjacent linear paths with tip-to-tip registration between the corrugations of the two mediums while the adhesive is caused or allowed to set at least partially, at least one outer liner (11; 119, 120) being applied either before or after the corrugated mediums are conveyed along the linear paths in which the tips of their corrugations are secured together, whereby the corrugating mediums are corrugated by being passed between separate pairs of corrugating rolls (5, 6; 103, 104, 105, 106) and that, after leaving the corrugating rolls, upon being brought together at the beginning of their linear paths, they are pressed together by pressing the tips of the two mediums into contact with one another while the adhesive is being caused or allowed to set at least partially, characterized in that pressure is additionally applied by opposed linear conveyors (23, 24; 112, 115).
A process according to claim 1 in which two outer liners (7) are joined to the respective corrugated mediums (11) before the mediums are brought together to be joined to one another.
A process according to claim 1 in which two outer liners (119, 120) are joined to the respective corrugated mediums (101, 102) after the corrugated mediums have been joined to one another.
Apparatus for manufacturing corrugated board comprising two layers of corrugated medium joined together with tip-to-tip registration between the corrugations of the two mediums, without an intermediate liner, and with at least one outer liner, comprising means (4-6) for forming two single-faced webs (2; 18), each comprising a corrugated medium (7) attached to a liner (11), means (9, 10) for applying adhesive to the tips of one of the corrugated mediums, and means (19-22) for bringing the corrugated mediums into contact with one another and for then conveying the two mediums along linear paths with tip-to-tip registration between their corrugations while the adhesive is being caused or allowed to set at least partially, characterised by opposed linear conveyors (23, 24) which apply pressure to the mediums urging them together while they are moving along the linear paths.
Apparatus according to claim 4 in which the opposed conveyors comprise a number of pairs of opposed belts (23, 24).
Apparatus according to claim 4 or claim 5 in which the opposed conveyors (23, 24) are arranged to move along a pressure chamber (30) adjacent to the conveyor (23) bearing on the liner of one of the single-faced webs (18).
Apparatus according to claim 6 in which a number of parallel belts (24) bearing on the liner remote from the pressure chamber (23) are arranged to move through grooves in a support plate which supports the adjacent liner in areas lying between the belts.
Apparatus according to any one of claims 4 to 7 in which each of the single-faced webs is arranged to move from its single-facer machine (3) via a register conveyor (19, 20) and along a path of variable length including a tensioning roll (14, 17), and in which the speeds and timing of the register conveyors are controlled to bring the mediums into tip-to-tip alignment, and the speed of each single-facer machine is controlled in response to the position of the corresponding tensioning roll.
Apparatus according to claim 8 in which the means for controlling the rotation of the two register conveyors (19, 20) comprises flute count encoders (35, 36) adjacent to the respective register conveyors.
Apparatus for manufacturing corrugated board comprising two layers of corrugated medium joined together with tip-to-tip registration between the corrugations of the two mediums, without an intermediate liner, and with at least one outer liner, comprising means (103, 104; 105, 106) for separately corrugating the two webs (101; 102) of corrugating medium, means (111) for applying adhesive to the tips of one corrugated medium, and means (104, 108) for bringing the corrugated mediums together and for then conveying them along adjacent linear paths with tip-to-tip registration while the adhesive is being caused or allowed to set at least partially, and including means for applying at least one outer liner (119, 120) to the joined corrugated mediums, characterised by opposed linear conveyors (112, 115) which apply pressure to the two corrugated mediums urging them together while they are moving along the linear paths.