Injection moulding

An apparatus for injection moulding plastics material to form an article, the apparatus comprising male and female mould members, the female mould member being a female mould defining an internal moulding cavity having flat wall surfaces, and the male mould member comprising a plurality of deflectable cores each having a free end, a flat end surface and flat side surfaces the respective surfaces of each core facing respective ones of said wall surfaces, the free end being arranged so as, in use, to extend into the cavity so as to define a moulding space into which plastics material can be injected to mould the article;

• and at least one inlet for plastics material into the mould space;
• the improvement that there is associated with the free end of each core at least one formation on one of the flat surfaces of one of the mould members, the at least one formation extending beyond the plane defined by the facing flat surface of the other mould member and being so disposed and arranged that, during mouldings, a space is defined at the free end of each core, from which space the flow of plastics to adjacent such spaces is restricted by said at least one formation, the at least one inlet being disposed such that of the volume of the mould, said spaces are first filled so that the free ends of the cores are entrained by respective masses of the injected plastics material so that during subsequent filling of the remainder of the space surrounding the core, deflection of the core under the action of the injected plastics material results in a pressure imbalance tending to reduce the deflection of the core.