EP0344685B1 - Laminating machine in a corrugating installation - Google Patents

Description

The invention relates to a gluing machine in a corrugated cardboard system according to the preamble of claim 1.

A gluing machine in a corrugated cardboard plant has the task of activating the glue between sheets arranged one above the other and bringing about the gluing. For this purpose, the gluing machine has heating plates which are heated with steam, for example. The sheets to be glued one above the other are moved along the surface of the heating plates and pressed against the heating plates with the aid of pressing means. This is done, for example, with the aid of a belt and / or rollers, but also with the aid of compressed air that is generated within a hood, which is placed above the heating plates. A gluing machine is usually divided into a heating section and a pulling section. The pulling section serves primarily for the translational movement of the corrugated cardboard, with cooling inevitably taking place in this area since heating is not carried out. It should be disregarded in the following considerations.

In the simplest case, the gluing machine is used to glue a single-shaft, single-sided sheet to an outer cover sheet. For this purpose, both webs are passed over preheating cylinders, and the one-sided web is provided with glue in a coating unit, more precisely, the shaft tips of the one-sided web are coated with glue so that the outer cover web can be glued to the shaft tips. Often, however, two or three one-sided webs have to be connected. For this purpose, the one-sided webs are each guided separately, in parallel, via a preheating cylinder and an applicator unit, the outer cover web being guided to the gluing machine in the manner described above.

In the simplest case described above, the heat of the heating plates must penetrate the outer cover sheet in order to obtain the glue. With multi-walled cardboard, the heat must be passed over the outer cover sheet and at least one one-sided sheet to get to the glue between two one-sided sheets. The thermal conductivity of paper is not particularly good. A greater thermal resistance is formed by a web that is corrugated on one side, in which the corrugation is only in line contact with the cover webs. It therefore takes a relatively long time until, in the case of multi-walled cardboard, a sufficient temperature is also established within the layers in order to achieve the desired activation of the glue. There are glues that can be activated even at lower temperatures, but these are relatively complex and expensive compared to conventional glues. Due to the described phenomenon, only a relatively low production speed can be used in the production of multi-walled cardboard. If a higher production speed is to be run, so much heat must be supplied in the first part of the heating section that there is a risk of overheating the glue and / or the paper in the lower webs. However, this results in poor bonding and / or there is "burning" of the corrugated cardboard and / or warping. In any case, the quality of the corrugated cardboard will decrease.

From DE-OS1561524 it is known to separate heating zones from one another and, for example, to feed a one-sided web to the second heating zone. In the known gluing machine, however, the applicator is arranged above the second heating section and - due to this - the pressure belt is placed below the second heating zone. However, such a construction has disadvantages.

The application of heat with the help of the heating plates from top to bottom is unfavorable because it is opposite to the natural heat flow. There is therefore considerable heat loss and there are also problems with setting a predetermined heat (setting temperature).

Another disadvantage is that the applicator is arranged above the heat source and therefore requires suitable insulation so that the glue in the applicator is not heated inadmissibly. Otherwise there is a risk that the glue is already heated to the setting temperature, which of course must be avoided.

The loading rollers for the belt below the heating zone are also disadvantageous in the known gluing machine. They require additional effort or energy and special design measures.

The division of the heating section into different heating zones is exclusive in the known gluing machine due to the necessary subdivision of the weighting device or weighting belt. For the first heating zone, the weight belt is located above the heating zone and in the second heating zone below. The division of the weight belt requires additional drives and corresponding controls, which increases the outlay on equipment.

The invention has for its object to provide a gluing machine in a corrugated cardboard system, which allows to produce multilayer corrugated cardboard with high production speed with little equipment and inexpensive heat.

This object is achieved by the features of the characterizing part of patent claim 1.

The pasting machine according to the invention or its heating section is divided into at least two sections which are spaced apart from one another in the working direction. In the space between the heating zone sections, an applicator is arranged below their working level, which interacts with the underside of the bottom web. Below the working level of the gluing machine, a feed means is also assigned to an intermediate space for feeding a web to the next section. In the case of a gluing machine of this type, either a one-sided web and a cover web are fed into the first heating section or two one-sided webs are fed. If, for example, a double-corrugated cardboard web is to be produced, the outer cover web is first introduced into the subsequent second heating section. The applicator arranged in the space between the heating sections carries the glue onto the shaft tips of the lower sheet, so that the cover sheet in the subsequent heating zone section with the lower one-sided sheet can be glued. If a three-corrugated cardboard is to be produced, the third one-sided web is fed in the space between the first two heating sections, while the outer cover sheet is fed in the space between the second and third heating sections.

The fact that the feeding of the single-sided corrugated cardboard and the cover sheet one after the other and over the length of the gluing machine, for example at two to three points, enables higher production speeds to be achieved. The heat required to gel the glue does not have to be applied at once for all the papers to be bonded, rather the heat application process takes place in stages. This advantage is obtained without the overall length of the gluing machine having to be increased significantly. In addition, the gluing machine according to the invention favors the processing of printed and in another form surface-treated outer cover sheets. The reason is that these webs with their sensitive surface do not have to be drawn over all heating plates for an unnecessarily long time. They are therefore not exposed to the relatively high pressure and heat in the first sections of the heating plate. A significant increase in quality is therefore obtained.

In the pasting machine according to the invention, heat is applied from below with the aid of the heating plates, as is also customary in the prior art, which accommodates the natural heat flow. Heat losses compared to heating zones built in a unit therefore do not have to be accepted. Because the application unit for glue is arranged in the space between the heating zone sections below the working level, no heat insulation is required for the application unit. The arrangement of the supply means for the supply of a web to the second, third, etc. heating zone section below the working level of the heating plates in the space between the heating zone sections can be accomplished with little outlay in terms of apparatus and takes advantage of the space already available in a pasting machine.

Depending on which cardboard is to be produced, it is not necessary to use a coating unit in the space between the heating sections located behind one another. Therefore, an embodiment of the invention provides that the height of the application unit arranged in the intermediate space is adjustable. The applicator is expediently constructed in such a way that the glue application roller protrudes somewhat with its circumference from the plane of the heating plate surface. If the application unit is not required, it is adjusted downwards by a small amount so that it disengages from the lower track. It goes without saying that instead of a total adjustment of the application mechanism, an adjustment of the application roller is also possible.

In the case of multi-corrugated cardboard, some of the webs are fed in the interspaces, which therefore have corresponding feed means. The webs can also be fed below the heating section. Alternatively, the tracks can also be initiated from the side. In any case, according to a further embodiment of the invention, it is expedient if the supply means have a heating cylinder or the like. By arranging a heating cylinder immediately in front of a heating zone section, only a slight cooling occurs between the heating cylinder and the heating zone section, so that the latter must heat the assigned web to a lower temperature than is the case, for example, in the prior art, in which the heating cylinders are located in front of the application unit and are therefore at a relatively large distance from the gluing machine. In the pasting machine according to the invention, less thermal energy is therefore required compared to the prior art.

As mentioned at the beginning, an application unit and a preheating device can be assigned to the first heating zone section. In this context, a further embodiment of the invention provides that two preheaters and an applicator are arranged upstream, one preheater is connected upstream of the applicator and the other preheater is arranged directly at the beginning of the heating zone. Only a heating cylinder therefore needs to be arranged at a certain distance from the gluing machine. The upstream application mechanism is also expediently adjustable.

In the pasting machine according to the invention, the lower one-sided web with the corrugation is placed against the heating plates in the case of two- or three-ply cardboard. With conventional gluing machines, the heating plates run transversely to the working direction. With this cross arrangement there are discontinuities between the heating plates and can possibly affect the curl. Therefore, an embodiment of the invention provides that parallel heating plates extend in the heating zone sections in the longitudinal direction. In this way, there are no discontinuities in the heating zone sections where the waves can be damaged.

According to another embodiment of the invention, the first one-sided web is fed directly to the first heating section and the associated cover sheet via a preheating cylinder in the space between the first and second heating sections. In this embodiment, an upstream application unit or an upstream preheater is eliminated. The space required by the application unit and the preheater is therefore fully available for the subsequent system. However, it is necessary to add a fourth section to the heating section if three-wall corrugated cardboard is to be produced.

• Fig. 1 zeigt schematisch die Seitenansicht einer erfindungsgemäßen Beklebemaschine.
• Fig. 2 zeigt schematisch eine zweite Ausführungsform der erfindungsgemäßen Beklebemaschine.

The invention is explained in more detail below using an exemplary embodiment.

• Fig. 1 shows schematically the side view of a pasting machine according to the invention.
• Fig. 2 shows schematically a second embodiment of the pasting machine according to the invention.

A gluing machine 10 in a corrugated cardboard system, not shown, has three heating zone sections 11, 12 and 13, which are arranged on a base 14. Spaces 15 and 16 are provided between these. The parallel heating plates, not shown in detail, extend in the working direction, ie in the direction of the arrow 16. In the intermediate space 15, an applicator 17 is arranged, the applicator roller 18 of which forms the highest point of the applicator 17. The height of the applicator 17 is adjustable, as indicated by the double arrow 19. A second application unit 20 is arranged in the intermediate space 16. It is also adjustable in height according to double arrow 21. The first heating zone section 11 is preceded by an applicator 22, the position of which can also be changed in accordance with the double arrow 23. The commissioned work 22 A preheating cylinder 24 is arranged upstream. A second preheating cylinder 25 is arranged directly in front of the heating zone section 11 below its working level. Pre-heating cylinders 26, 27 are arranged in the spaces 15 and 16 and are also below the working planes of the assigned heating zone sections 12 and 13, respectively.

The pasting machine shown works as follows. The application unit 22 is supplied with a web 30 that is corrugated on one side via the preheating cylinder 24 (also indicated by the circle 31). If only a single-shaft web is to be produced, a cover web is fed via the preheating cylinder 25, which is glued in the usual way to the one-sided web 30, the latter being provided with glue with the aid of the applicator 22. A load belt 50 is arranged as an endless belt with its working strand above the heating zone sections 11, 12 and 13 in order to press the webs against the heating zone sections.

If, on the other hand, a twin-shaft web is to be produced, a second one-sided web 33 is fed in via the preheating cylinder 25, also indicated by the circle 34. In the heating zone section 11, two single-sided webs are therefore glued to one another to form a double-shaft web 35, indicated by the circle 35.

The cover sheet, which is glued to the twin-shaft sheet 35, is fed in via the preheating cylinder 26. Finally, if a three-shaft web is to be produced, the third one-sided web 37 is supplied via the preheating cylinder 26, also indicated by circle 38. The cover web 39 is then supplied via the preheating cylinder 27, also indicated by a double circle 40. In the last heating zone section 13, therefore the three-shaft path 41 is formed, also indicated by circle 42.

As can be seen, the individual webs are fed in successively, so that the heat generated by the heating zone sections 11, 12 and 13 only has to penetrate a cover layer or a one-sided web in order to reach the bond point. The application units 17 or 20 will not required, they are adjusted out of engagement with the assigned path.

In the exemplary embodiment, all the webs to be introduced into the spaces 15 and 16 are fed in the working direction below the gluing machine. It goes without saying that these webs can also be fed laterally by means of corresponding deflection rollers.

In the embodiment according to FIG. 2, all parts, insofar as they have already been shown and described in FIG. 1, are provided with the same reference numerals, but to which the index a has been added. It can be seen that an application unit and a preheating cylinder, as are shown schematically in FIG. 1, are not provided. Instead, the first heating section 11a is preceded by a heating section 111 which is structurally similar to the other heating sections 11a, 12a and 13a. It is arranged at a distance from the heating section 11a and thus forms an intermediate space 112, in which an applicator 113 with an applicator roller 114 is arranged. The height of the applicator 113 can be adjusted according to double arrow 115. In addition, a heating cylinder 116 is arranged in the space.

As can be seen, the one-sided web 30a (shown in circle 31a) is fed directly from the bridge to the first heating section 111. The cover sheet 33a, on the other hand, is fed in below the first heating section 111 and placed over the heating cylinder 116 against the underside of the first one-sided sheet and glued to the heating section 11a. If, on the other hand, two- or three-corrugated corrugated cardboards are to be produced, the second or lower one-sided web is fed to the second heating section 11a via the heating cylinder 116.

In the second embodiment as well as in the first embodiment, the advantage is obtained that the outer cover sheet is heavily protected and can therefore be pre-printed or treated in a different way in a favorable manner.

The applicators according to the embodiments of FIGS. 1 and 2 can not only be height-adjustable but also laterally adjustable, for example to move them out of the gluing machine for cleaning purposes.

Claims (7)

1. Gluing machine used in a corrugator, situated downstream of at least one single-face corrugator and of which the heating section (11, 12, 13) comprises on a processing plane heating plates over which are to be carried superposed single-face webs (30, 33, 37; 30a, 33a, 37a) and, if necessary, a cover web (39; 39a), destined to be glued to one another under the effect of pressure exerted from above by a pressing means directed against the heating plates, characterised by the fact that the heating section includes only one processing plane subdivided in the running direction into at least two sections (11, 12, 13) by an intermediate space (15, 16), that an applicator (17, 20) is arranged in each intermediate space (15, 16) on the said claim, and that underneath the said processing plane in every intermediate space (15, 16) are foreseen feeding means (26, 27) for a single-face web (37; 33a; 37a) or a cover web (39; 39a) so that in case of double- or plurifluted board being processed, the lower single-face web will be applied onto the flutes against the heating plates.

2. Gluing machine according to claim 1, characterised by the fact that the applicator (17, 20) situated in the intermediate space (15, 16) is adjustable vertically and/or can be moved out sidewise.

3. Gluing machine according to claim 1 or 2, characterised by the feeding means comprising a heating cylinder (26, 27).

4. Gluing machine according to one of the claims 1 to 3, characterised by the fact that two pre-heating devices (24, 25) and an applicator (22) are arranged upstream, that a pre-heating device (24) is arranged before the applicator (22), and that the other pre-heating device (25) is situated immediately at the beginning of the heating zone.

5. Gluing machine according to claim 4, characterised by the upstream applicator (22) being equally adjustable.

6. Gluing machine according to one of the claims 1 to 3, characterised by the fact that the first single-face web (30a) is fed into the first heating section (111) immediately, and the pertaining cover web (33a) over a heating cylinder (116) contained in the intermediate space between the first and the second heating zones (111, 11a).

7. Gluing machine according to one of the claims 1 to 6, characterised by the parallel heating plates extending lengthwise in the heating zones (11, 12, 13).

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