Spritzgussverfahren und -maschine

摘要

1390912 Injection moulding BRITISH UNITED SHOE MACHINERY CO Ltd 15 May 1972 [15 May 1971] 15139/71 Heading B5A In a method of injection moulding, e.g. shoe soles, after completion of injection, a plug P (Fig. 2) is inserted into the sprue bore 22 which leads to the mould cavity, to prevent escape of moulding material from the bore 22. In a first embodiment (Fig. 2) injection is effected through a passage 12 in an injection head 10 and an aperture 38 in a slide member 36, a purging member 13 being retracted beyond an inlet port (not shown) extending into the passage 12 from a mixing chamber. On completion of injection, the purging member 13 is advanced to the position seen in Fig. 3 (not shown) thereby ejecting residual material from the passage 12 into the aperture 38 and bore 22. The slide 36 is then moved to bring a second aperture 40 into line with the passage 12 and bore 22, the aperture 40 containing a plug P left from the preceding injection operation. By advancing the member 13 to the position seen in Fig. 4 (not shown) the plug P is pushed into the bore 22. The next injection is effected through the aperture 40, and partly soldified material (P1) remaining in the aperture 38 is used for the plug. In a second embodiment (Fig. 7) the slide 36 of the first embodiment is replaced by a generally circular member 86 which has a plurality of apertures 90 and is rotatable on a shaft 88. A plurality of mould assemblies are provided, part of one being shown at 70 with its sprue bore 72. A mixing chamber 74 is connected through a port 75 to an injection passage 62 containing a purging member 63. Operation is similar to the first embodiment but the member 86 rotates through #th of a revolution where eight mould assemblies are provided. In a third embodiment (Fig. 9) the plug P 2 which is inserted into the sprue bore 122 is punched out of a ribbon R of resilient expanded plastics material by a purging member 113. This member 113 is a close fit in the injection passage 112 which is connected by a port 125 to a mixing chamber (not shown). Injection is effected through the hole in the ribbon R formed during the preceding injection operation. The ribbon is moved forwards by automatic feeding means. In a fourth embodiment (Fig. 10) pre-formed plugs P 3 slide from a hopper 195 down a raceway 194 and are fed by loading mechanism 196 into one of a plurality of apertures 190 in a circular member 186. The member 186 is rotated automatically to bring the apertures 190 in turn into line with an injection passage 162. An inlet port 175 connects the passage 162 to a mixing chamber (not shown).