| 摘要 |
1,111,287. Injection moulding cartridge cases. IMPERIAL METAL INDUSTRIES (KYNOCH) Ltd. 14 June, 1966 [8 July, 1965; 3 Feb., 1966], Nos. 29008/65 and 4805/66. Heading B5A. [Also in Division F3] A preform tube 1 of a plastics cartridge case, which has been molecularly oriented by stretching, is inserted in the mould 40 between a sleeve 45 and a core 48 carried by backplate 49. Plastics material to form a head 56 on the case is injected into a space between the core and a sprue bush 54. The tube is a polymer or copolymer of ethylene with a density from 0À94 to 0À96 g./c.c. and a melt flow index not more than 0À5. The head material is a polyolefine, an acrylonitrile/butadiene/styrene copolymer, nylon, or a polymer or copolymer of an acetal. In moulding, the tube is expanded into a counterbore 41 and is mechanically interlocked with the head, but preferably the temperature is such that no bonding occurs. The tube is sealed against the core by a deformable washer 43 fitted outside the tube and compressed by the sleeve 45. A cooled ejector rod 50 is fitted in the core. The cartridge may be moulded in apparatus where the washer 43 is replaced by an internal seal (22), Fig. 3 (not shown). |
