Rubber-lined tools for injection moulding thermoplastics materials - for high pressure moulding of undercut forms using inexpensive tooling

摘要

Injection moulding tools comprise pairs of solid rubber shells contained by a relatively simple rigid casing of e.g. clamped or bolted sheet metal or channel. Used esp. for moulding thermoplastic materials into shapes requiring undercut mould cavities and/or support of inserts. The mould shells can be made readily by moulding around a master shape, can disengate elastically from the master and from enclosed mouldings. The rubber shells transmit the injection pressure elastically to all parts of the cavity, ensuring consolidation and recovering to compensate for moulding shrinkage during cooling. Low heat transfer into the mould walls allows long shallow cavities to fill before setting up.