Patent DE-19836773-A1 (DE)
Title: Continuous press for the production of chipboards and fiberboards has a heated press stretch within the press stage lengths and a movable cooled press stage to set the temperature according to the bonding agent hardening
Inventor: BIELFELDT FRIEDRICH B
IPC: B30B5/06
Filed: 1998-08-13
Abstract: Continuous production of chipboard and fiberboard materials involves cooling the surface of the board material to be pressed before reaching reaction temperatures. The reaction temperature hardens the bonding agent in the material. The press cooling stage (LK) has sufficient length for hardening the board material and for a non-damaging steam pressure within the interior of the final board. The surface cooling of the board material is through the delivery of a coolant medium through drillings in the press/cooling plates and/or by spraying cold water at the friction-reduction units and the steel belts by vertical drillings at the press plate cassettes and/or press cooling plates. Only sufficient water is sprayed to generate steam which can be extracted. The heat generated from the cooling action at the friction-reduction units and/or the steel belts is returned to the appropriate heating system. The extracted steam is condensed in a water bath, and any floating oil or other matter is removed from the water surface. The water condensation is returned in a cooling circuit for spraying. The cooling of the friction-reduction units and steel belts is set according to the hardening temperature of the bonding agent, at  <= 140 deg C for boards of wood materials and  <= 120 deg C for compound plastics boards. The press cooling stage (LK) has a variable movement to the press stretch (LH) and back, to give a match with the bonding agent hardening temperature and/or the nature and consistency and thickness of the board material. The final moisture content of the finished board over the press cooling stretch is 0-3% below the moisture content at the entry, and it can be controlled to match the entry moisture level. The heat recovery from the heat loss from the press plate cooling, the cooling of the friction-reduction units and the steel belts is used to preheat the water supply to give the board steaming and/or the water supply for the steam drying units at the fiber or chip preparation stages and/or the heating medium itself to heat the press plates in the continuous press.  An Independent claim is included for a continuous board press (1) where the press stretch (L) is divided into a heated press stretch (LH) and a cooled press stretch (LK). A press plate cassette, which can be moved within a defined path length (M), moves the cooling press stage (LK) within the heated press cooling stage (LH) to vary their overlap. Preferred Features: Additional drillings are at the press plates which can be cooled in the cooling press stage (LK), in a number of spaced rows across the plate width, for cold softened water to be pressed through against the friction-reduction units and the steel belts (5,6), to be extracted as steam from the rolling zone and/or through the drillings in the surfaces of the press plates or out through the sides at the steel belts (5,6). The friction-reduction tube units are heated by the feedback circuit for the heaters. Insulation strips are fitted between the final heated press plates (11) and the leading cooling press plates. The press plate cassettes are separated from each other and from the nearest heated press plate (11) by insulating strips.