GB1085764A - Improvements in methods of and means for injection-moulding hollow articles - Google Patents

Abstract

1,085,764. Injection moulding. DESMAWERKE G.m.b.H. May 17, 1965 [May 22, 1964], No. 20656/65. Heading B5A. A hollow article is moulded either by the two-stage injection of rubber or synthetic plastics material into the cavity 11 between a core 18 and mould 16, the first stage injection providing inserts which support the core against twisting or bending during the second stage injection, or by a one-stage injection using metal or plastics inserts. In both cases the inserts remain as part of the finished article. In the embodiment shown, for moulding a hot water bottle, the core, supported at one end by a holder 19, is given support by a first injection at a relatively low pressure through channels 23 with pre-vulcanization or pre-gelling of the material which then surrounds the core at its end remote from holder 19. Subsequently cavity 11 is filled by injection at high pressure e.g. 1500 atmospheres, through channels 24. A suspension tab 12 is moulded whose eye is formed by a pin (13), Fig. 2 (not shown). To allow removal of waste material from channels 23, 24 the core may be horizontally split or the channels may be tapered. Alternatively, the moulding material may be injected into cavity 11 from opposite sides via channels in the mould. In a second embodiment, Figs. 3 and 4 (not shown), core (18) is held by a combined ring (14), which encircles pin (13), and support member (17). In a modification, Figs. 5 and 6 (not shown), core (18) is supported by members (20).