| 摘要 |
1,150,366. Moulding expanded plastics. KOPPERS CO. Inc. 6 Oct., 1967 [10 Oct., 1966], No. 45940/67. Addition to 1,011,356. Heading B5A. [Also in Division C3] Expanded thermoplastics articles, e.g. of polystyrene and copolymers thereof (see Division C3) are moulded in a cavity 26, defined between perforated metal shells 23 provided with steam heating/water cooling coils 24, which is filled with unexpanded or partially preexpanded heads at an inlet 69 to which they are delivered from a heated hopper, e.g. at 150‹ to 170‹ F., entrained in a stream of hot air or nitrogen in which they are heated to from 5‹ to 10‹ F. above the polymer softening point but below the point at which substantial granule expansion occurs. The granule delivery pipe 65 to the mould is provided with a steam heated jacket 91 and with a circumscribing perforated vent 113 to atmosphere or vacuum, for removing back pressure arising during mould filling. The mould shells 23 are pre-heated to 200- 230‹ F. The delivery of hot air is halted when the mould is filled and the granule inlet closed by a hydraulic or pneumatic actuated ram 77 which may also be used to vary the rate of delivery of the granules into the mould. The filled heated mould is subjected to vacuum from the mould chests 22 to expand and fuse together the granules and the mould is cooled to 150‹ to 180‹ F. and then opened to eject the article by compressed air applied to the female mould chest. |
