IMPROVEMENTS IN CO-INJECTION MOULDING

摘要

The present invention relates to advancements in injection moulding and in particular to a method and apparatus for co-injection moulding articles of complex non symmetrical geometry. The method forms a multilayer injection moulded article comprising an outer skin of a first material and a central core of a second material which is encapsulated by the outer skin. The first and second materials are injected in a single stream into a cavity of an injection mould, with the second material encased within the first material. The flow of the stream is controlled by means of flow paths within the mould cavity such that both the first and second materials are present in at least one first area of the mould cavity and that only the first material is present in at least one second area of the mould cavity. The flow paths include at least one primary flow path in the first mould cavity area which divides into at least two secondary flow paths. The resistance of a first of the secondary flow paths in the at least one first mould cavity area is reduced relative to that of a second of the two secondary flow paths, which is in the at least the second mould cavity area.