Plastic and nonmetallic article shaping or treating: processes – With measuring – testing – or inspecting
Reexamination Certificate
2001-02-06
2003-05-20
Lechert, Jr., Stephen J. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With measuring, testing, or inspecting
C264S040400, C264S118000, C264S129000, C264S145000, C264S157000, C264S160000, C264S161000, C264S162000, C264S172110, C264S237000, C264S348000
Reexamination Certificate
active
06565780
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method for the continuous production of boards of ligneous material and an apparatus for the practice of the method. The term “ligneous material boards” includes chipboards, fiber boards, plastic boards and flake boards as well as plastic boards made of combined portions of wood and plastic as well as plastic with and without strengthening inserts. Such a method with apparatus, from which the invention sets out, is the subject of the German patent application DE 199 19 822, filed May 1, 1999, which is hereby incorporated by reference.
The invention according to the German patent application above was addressed to the problem of conducting the process of cooling the boards after the boards are produced, so that the “hydrolysis effect” no longer occurs, distortion of the boards is prevented, and the climatization is for the most part economized.
The method of the German patent application above consisted in subjecting the hot board strand to shock cooling immediately after leaving the continuously operating press and carrying it through a double-belt holding apparatus whose holding belts exert a specific bearing pressure of no more than 0.05 N/mm
2
onto the surfaces of the board strand, and the backs of the holding belts are sprayed with an appropriate coolant as they run, the action of the shock cooling thus performed being continued until the temperature in the center of the board strand has reached approximately 80° to 100° Celsius.
The method accordingly consists in cooling the board strand very quickly in a double-belt holding apparatus immediately after leaving the hot press, by a kind of shock cooling. In the double-belt holding apparatus the surface temperature of the board strand is reduced from about 160° Celsius to about 30° Celsius. The center of the board must be cooled in the double-belt holding apparatus from 115° Celsius to 100° Celsius and less, preferably 80° Celsius.
The apparatus according to the German patent application above consisted in the fact that the cooling apparatus is arranged as a double-belt holding apparatus directly following the continuously operating press and is designed with an exerted holding pressure of up to a maximum of 0 to 0.05 N/mm
2
and a plurality of rows of coolant spray nozzles are disposed on the backs of the belt areas that are in contact with the board strand.
The present invention relates to a further development of the method described in the German patent application above and of the apparatus for the practice of the method. For it has been found that, during production, the belt run-out occurring in the continuously operating press causes a considerable belt run-out in the double-belt holding system. Furthermore, transporting a burst board strand through the double-belt holding system is problematical. Damage can be done thereby to the steel belts and in the double-belt holding system itself.
The present invention is addressed to the problem of presenting a method by which any belt and board strand run-out occurring in the double-belt holding apparatus will be prevented from propagating and causing damage therein, and to create an apparatus for the practice of the method.
SUMMARY OF THE INVENTION
The solution as to the method is that the hot board strand is divided into single boards of predetermined length immediately after leaving the continuously operating press and is then subjected to shock cooling while being carried by a double-belt holding apparatus whose holding belts exert a specific bearing pressure of 0.05 N/mm
2
on the surfaces of the single boards and the backs of the holding belts are sprayed with a suitable coolant as they pass, and the action of the shock cooling thus performed is applied until the temperature in the center of the single boards has reached approximately 80° Celsius to 100° Celsius.
The apparatus for the practice of the method includes a cooling apparatus in the form of a double-belt holding system with a maximum applicable holding pressure of 0 to 0.05 N/mm
2
; and immediately following the continuously operating press and ahead of the cooling apparatus a diagonal sawing system is disposed for cutting the board strand into individual boards, and several rows of coolant spray nozzles are disposed on the backs of the holding belts making contact with the single boards.
The single boards thus severed cause no problems in regard to the belt run-out while being cooled in the double-belt holding apparatus, since they can be aligned absolutely by simple adjustment as they run along the loading and production axis.
It is also advantageous if the single boards, after being cut apart, pass through a quality checking apparatus, for example a burst detection or gap measuring device, and are carried over a weigh-scale, and rejected boards are removed from the production line by a board deflector ahead of the cooling process. It also saves energy to use in the double-belt holding system the fresh water from the chopper preheating system. In this manner the invested costs and the operating costs of a cooling tower for operating the cooling system in the double-belt holding apparatus can be saved.
By the use of the cooling system according to the invention, it becomes possible to polish in the production line, since polishing is possible only at a board surface temperature below 60° Celsius since otherwise the polishing belts become clogged. Due to the polishing operation it is possible to do without the intermediate supports such as those, for example, which are provided in MDF production.
Additional advantageous measures and embodiments of the subject matter of the invention will be found in the subordinate claims and in the following description with drawing.
REFERENCES:
patent: 5643376 (1997-07-01), Gerhardt
patent: 6074193 (2000-06-01), Kratky et al.
patent: 199 19 822 (2000-11-01), None
Lechert Jr. Stephen J.
Maschinenfabrik J. Dieffenbacher GmbH & Co.
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