| 摘要 |
1,154,259. Sizing and cooling extrudates. CHEVRON RESEARCH CO. 14 Nov., 1967 [25 Nov., 1966], No. 51882/67. Heading B5A. Solid or hollow thermoplastic extrudate is sized and cooled using a sizing die 23 comprising abutting porous annulµ 26a-26e and 27a-27e, the former set 26a-26e each providing a cavity connected to a source of cooling liquid, e.g. water, via a conduit 29, the cavities being sealed peripherally by metal plates 28a-28e and laterally by coatings, e.g. of resin, on the exposed surfaces of annulae 27a-27e. In operation, die 23 is immersed in cooling liquid within a tank (4), Fig. 1 (not shown), which liquid is fed to the tank via a valve (11) and maintained at a pressure below atmospheric by a vacuum system comprising a pump (8) and Venturi (9). Liquid is pumped via conduits 29 into the cavities and passes through the associated porous annulus 26a- 26e to form a cooling and lubricating film of liquid between the internal surface of the die and the extrudate. The liquid of the film circulates by passing radially outwardly through annulae 27a-27e into tank (4). A typical extrusion plant incorporating the sizing die comprises a haul-off mechanism (15), Fig. 1 (not shown), and cutter (16). The annulae 26, 27 may be of sintered metal or porous ceramics, the cooling liquid may contain a dye and specific thermoplastic materials mentioned are polyethylene, polypropylene, poly - 1 - butene, poly - 4 - methyl - 1 - pentene, polystyrene, polymethyl methacrylate, polyethylene terephthalate, polyvinyl halides, polyacrylonitrile, polyhexamethylene adipimide, polycaproamide and polycaprolactam. |
