| 摘要 |
In the prodn. of board materials, both sides of the hot board strand are cooled in a shock cooling action by water sprays, in an initial cooling stretch with evaporation zones, in a variable length set according to the board thickness. The board is held by a number of mangle rollers to apply a multiple pressure. This is followed directly by a second cooling stretch, where a light specific pressure is applied by a twin-belt holding station, where the reverse sides of the continuous belts are sprayed with a coolant. The twin holding belts apply a max. specific pressure on the board material surfaces of 0.05 N/mm<2>. The shock cooling by the water sprays gives a temp. within the center of the board of 80-100 deg C. The applied water by the sprays is set according to the board thickness at a rate of 30-300 g/m<2>. The water sprays are composed of droplets from fine to coarse dimensions, according to the characteristics required in the final product. A spray of fine droplets is used for medium density fiberboards (MDF) and a spray of coarse droplets is used for oriented structural boards (OSB). Additives are in the water spray in the initial cooling zone, to form compounds with formaldehyde such as urea or ammonium carbonate solution, and also neutralize the glue cracks such as an alkaline. The additives are applied before the board material enters the twin-belt holding zone. Directly after the twin-belt holding zone, the surfaces of the board material are ground and/or varnished or coated. An Independent claim is included for a board prodn. assembly with an initial water spray cooling station (21), with a direct water spray action from water jets (22), directly after the continuous hot press (1), and in a variable length (K1-Kv). The board strand (13) is held under a light pressure by mangle rollers (23) in the cooling station. A second cooling station is formed by the twin-belt holding system (12), which can be moved into a cooling zone (Kv). A number of rows of water spray jets (16) apply a coolant to the reverse sides of the belts at the twin-belt holding station (12). Preferred Features: A barrier belt (24) is at both side edges of the board strand (13) at the first cooling station (21), moving through the station with the board material.
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