Mould giving injection mouldings with clean surfaces - comprising press with system of three plates to form sub-cavities before final impressions

摘要

A mould, for injection moulding articles with clean surfaces and which have tapered sides (over at least part) has three moving plates and therefore two split planes. The first has a number of mould impressions, and the second has a cluster of sub-cavities connected with the injection hole on one side and the mould impressions on the other. When moulding these sub-cavities produce a waste sprue. The sub-cavities between the middle and back plates are connected directly with the injector opening in the front plate via a hole in the middle plate. The set of mould impressions is formed between the front and middle plates. The flow duct from the sub-cavities leads to the mould impressions where an ejector ends and where the mouldings end at their smaller section, that section being widest at the front split plane between the plates. A simple low-cost method of producing clean mouldings, i.e. without surface flaws requiring dressing, is provided.