Hot runner injection moulding heat with a sleeve valve - which closes radial runner gates, for moulding without producing surface gate blemishes

摘要

Injection moulding appts. incorporating a hot runner system with radial gates emanating at >=1 levels from a column of melt, where the runner barrel is surrounded by a sleeve valve to seal the gates as the mould cavity tool is parted from the runner tool. Used esp. for multi-cavity tools producing mouldings with a high quality surface finish. The injection gate is positively closed off by the sleeve valve so that the moulding surface is not subject to any drag or adhesion by the sprue system as the moulding is ejected. Large gates can be used without resulting in gate marks on the moulding requiring machining or buffing.