Pressure plate arrangement for production of multilayer...

Adhesive bonding and miscellaneous chemical manufacture – Surface bonding means and/or assembly means therefor – With bending – folding – winding – or wrapping means

Reexamination Certificate

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Details

C156S205000, C156S210000, C156S583100

Reexamination Certificate

active

06257296

ABSTRACT:

PRIOR APPLICATIONS
This application claims priority from prior filed German application-Germany No. 198 15 863.7, filed Apr. 8, 1998.
GOVERNMENT SPONSORED RESEARCH
Not applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is in the field of devices for the fabrication of corrugated cardboard.
2. Brief of Description of the Background Art
The invention relates to a pressure plate arrangement for joining together a plurality of material webs each comprising at least one plain web and/or at least one corrugated web, to form a corrugated cardboard web. At least one of the material webs is provided with adhesive at least in sections. The arrangement comprises a contact pressure unit provided with a pressure plate, and a heatable counter pressure plate, between which the material webs to be joined are passed. The contact pressure unit and the pressure plate are provided with means to vary their separation from the counterpressure plate.
Pressure plate arrangements of this kind are known from the prior art. For example, the brochure “The Double-Facer Group”, Brochure No. 2 (694G) 0.5 of Messrs Peters Maschinenfabrik GmbH, describes an arrangement of this kind on Page 10. In this arrangement, the material webs provided with adhesive, contact the heatable counterpressure plate and are pressed against one another from the opposite side by means of the pressure plates. The supply of heat via the heatable counterpressure plate accelerates curing of the adhesive. Of course in the case of multi-layer corrugated cardboard webs, i.e. corrugated board webs having two or more webs (e.g. double-wall corrugated cardboard), the problem arises that the temperature in the corrugated board decreases with increasing distance from the heated counterpressure plate, so that complete drying of the adhesive points remote from the counterpressure plate takes a relatively long time. To counteract this problem, in the case of moving material webs it is either necessary to appropriately reduce the speed of movement in order to allow adequately long heat treatment of the adhesive locations, or else it is necessary to appropriately lengthen the heatable counterpressure plate. Alternatively, it is necessary to appropriately increase the amount of heat supplied per unit of time. Thus, the required heat treatment expense increases with increasing corrugated board thickness and/or increasing weight per unit area.
Of course there are economic and practical limits both to reducing the speed of movement of the material web, to lengthening the apparatus, and also to increasing the amount of heat supplied per unit of time via the counterpressure plate. It is, therefore, an object of this invention to realize a pressure plate arrangement of the above type whereby the adhesive curing process can be accelerated for the same speed of movement, the same apparatus length and the same heat supply via the counterpressure plate.
SUMMARY OF INVENTION
In a pressure plate arrangement of the above mentioned type this problem is solved by providing a heatable pressure plate. By heating both the counterpressure plate and the pressure plate it is possible to supply heat to the corrugated board from both sides. While the heat supply rate to the counterpressure plate remains constant, the heat supply as a whole can be increased and a more uniform temperature profile through the thickness of the corrugated board is produced. As a result, first the gelling, and then the curing of the adhesive is rendered more uniform through the thickness of the corrugated board. Thus, there is no longer a delay in curing with increasing distance from the counterpressure plate. Because of the fact that the curing process is rendered more uniform through the thickness of the corrugated board, the pressure plate arrangement according to the invention enables reduction of the treatment time required for curing. Consequently, the transit times are quicker in the production of corrugated board or else the minimum length required of the pressure plate arrangement is reduced for a moving corrugated cardboard web. This also applies to large corrugated board thicknesses and/or weights per unit area.


REFERENCES:
patent: 5244518 (1993-09-01), Krayenhagen et al.
patent: 5256240 (1993-10-01), Shortt
patent: 5456783 (1995-10-01), Sissons
patent: 5495092 (1996-02-01), Marschke et al.
patent: 5501762 (1996-03-01), Marschke et al.
patent: 5662765 (1997-09-01), Titz et al.
patent: 5788803 (1998-08-01), Sissons et al.
patent: 5915295 (1999-06-01), Lauderbaugh
patent: 6110095 (2000-08-01), Finke et al.
“The Double Facer Group,” Brochure No. 2 (694G)0.5 of Messrs. Peters Maschinenfabrik GmbH.

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