A METHOD OF PREPARING A MIXTURE OF PLASTICS MATERIAL AND FILLER MATERIAL FOR INJECTION INTO MOLDING DIES

摘要

1,260,166. Injection moulding apparatus. S. A. MeINNIS. 5 March, 1969, No. 3159/70. Divided out of 1,260,163. Heading B5A. In a method of preparing a mixture of plastics and filler materials for injection into a mould 112 the plastics material is supplied to a receptacle 10 in which it is melted and continuously circulated by a pump 20, the filler material is supplied to a receptacle 36 to which liquid plastics material can be supplied from the receptacle 10, the mixture being continuously circulated by a pump 50, and the mixture: is supplied to a holding receptacle 64 in which it is circulated by a pump 76 and from which it can be delivered to the mould 112. The receptacles 10, 36 and 64 are provided with heating jackets 14, 38 and 70 respectively to maintain the materials just above the liquefying temperature. Valves 30, 58 and 90 permit circulation through the receptacles or delivery to the next receptacle or the mould. When valve 90 is closed and pistons 166, 160 withdrawn, the pump 76 delivers the mixture through an injection gun 82 to the mould. When the mould is full additional material is supplied thereto by the piston 166 to compensate for shrinkage due to cooling. As shown in Fig. 4, the injection gun 82 is movable towards and away from the mould by means of a piston 122 fixed to the machine frame 110 and a movable cylinder 128. Piston 166 is operated by a piston 164 and cylinder 148. A piston 160 for clearing residue from a passage 102 in the injection gun is operated by a piston 158 and cylinder 142. Suitable thermoplastic materials mentioned are ABS, nylon and polythene, and fillers specified are glass or synthetic fibres, particulate A1 powder, woodflour, particulate asbestos and mica.