| 摘要 |
PCT No. PCT/EP94/00361 Sec. 371 Date Dec. 16, 1994 Sec. 102(e) Date Dec. 16, 1994 PCT Filed Feb. 8, 1994 PCT Pub. No. WO94/19169 PCT Pub. Date Sep. 1, 1994.The invention concerns a closable extrusion nozzle for thermoplastic materials, with a nozzle plate (4) containing nozzles permitting the extrusion of the thermoplastic material from a hopper (1) and with a perforated plate (7), disposed upstream of the nozzle plate, whose apertures (8) can be brought in and out of alignment with the nozzles by displacing the perforated plate (7) with respect to the nozzle plate (4). The nozzle plate (4), which is U-shaped in cross-section, with the arms of the U at right angles to the direction of displacement of the perforated plate, is designed as a housing for the perforated plate (7) enclosed within it. A sealing surface (15) on the perforated plate (7) rests against the flat housing floor (5) in which the nozzles (6) are located, there being a gap between the perforated plate (7) and the housing at least in the curved regions (16, 17) of the floor, and the region in which the seal is formed by the sealing surface (15) resting against the floor (5) being limited to a narrow zone round the nozzles (6).
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