Patent DE-19836742-A1 (DE)
Title: Continuous embossing press for chipboard/fiberboard materials comprises taking the hot board from the production press for water to be sprayed on the surface and carrying the board through structured embossing stages
Inventor: BIELFELDT FRIEDRICH B
IPC: B27N3/24
Filed: 1998-08-13
Abstract: Production of fiberboard and chipboard material with a structured surface comprises passing the board material through a continuous embossing press, then still hot, it is moved along a short path (A) into a covered transit stretch (B) where its upper surface is sprayed with water, then picked up by a press belt against its upper surface to be carried through a steam pressure zone (C1). To produce fiberboard and chipboard material with a structured surface, the board material is passed through a continuous embossing press. The pressed board emerging from the board press phase, and which is still hot, is moved along a short path (A) into a covered transit stretch (B) where its upper surface is sprayed with water at a rate of 112.5-225.0 g/m<2>, which cools the upper surface layer. The board is picked up by a structured press belt against its upper surface to be carried through a steam pressure zone (C1) where the steam vapor at the board surface is raised to a pressure up to 0.5 N/mm<2>. The continuous embossing press acts within the press zone (L) where the initial section (C2) has a steam pressure plasticizing action while the embossing pressure is applied at 3.5-4.0 N/mm<2> with the temperature increased to 200 deg C, and the pressure and temperature are maintained within a high pressure and embossing stretch (D). The final section in the press zone (L) is a drying and structure fixing stretch (E), where the embossing pressure is relaxed to 0.5 N/mm<2> and the temp. is reduced to 120 deg C. The passage of the board through the embossing process stages (B,C1,C2,D,E) is for a sufficient time span to give a durable embossed structure at the board surface. The specification is an addition to DE19718771.4. The water spray is at a temperature of 20 deg C to  <= 100 deg C. The board is cooled in the transit stretch (B) to a temperature of  <= 100 deg C. The steam vapor pressure is increased in the steam pressure stage (C) to 1.5-2.0 N/mm<2>. The time taken for the board material to pass through the five process stages is about 13 secs. The steam generated at the steam pressure increase stage (C1) is extracted, condensed, and returned to the board surface water spraying stage (B).  An Independent claim is included for a press control operation to give a board material with a smooth or a structured surface, with synchronization of the board press and the embossing press in a continuous production process. The water spray is disconnected, and the dividing line between a wet and a dry board surface is registered numerically. At the dividing line, the press plates are operated numerically without pressure to give a smooth board surface. When a dividing line is registered for a further wet surface section, the embossing press is activated to give the embossed board surface structure.  Preferred Features: When a board is being produced with a smooth surface, the heating is disconnected at the embossing plates. When the temperature of the press plates has returned to a normal level, the water spray action is resumed.  A further Independent claim is included for an embossing press assembly (40) located directly after the exit of the board (1) from the board production press (10), to give a continuous structured embossing to the upper surface of the board (1). The movement path (A) between the presses (10,40) leads into a transfer stretch (B), where water is sprayed on the board surface under a hood (6), before the board material enters the embossing press stretch (L). The embossing press action is applied within sub-zones where the steam pressure is increased (C1), the surface is plasticized with steam pressure (C2), a high pressure embossing stage (D) and a final drying and structure fixing stage (E).  Preferred Features: The embossing press (4) has flexible and continuous steel belts (25,26) with speed-controlled entry drums (27,28) and rigid mechanical deflection curves (17,18) at the other ends to pass round the press table and press ram. They are supported by units (13) to reduce friction against heated upper press plates (11) at the press table (22) and the press ram (23). A structured belt (19) of a woven metal wire mesh moves round the press ram (23) with the upper steel belt (25), round its own deflection drums (20,21). The upper sliding support plates (16) can be heated. The press ram (23) and the press table (22) are secured together by tie straps (14), with a setting mechanism to adjust the press gap between them. The tie straps (14) can be swung clear and telescopic rods drawn out for a change in the structured belt (19) at the embossing press (40). The embossing press system can be lifted clear by 50-100 mm along the embossing stretch (L), when producing a board (1) with a smooth surface.