Prodn. of hollow plastic mouldings - by making low melting pt. metal core, placing in mould, injection or blow moulding article, cooling, and melting out core for re-use

摘要

Plastic mouldings are produced with an internal hollow cavity; a core is first made of the shape of the cavity reqd. and in a metal whose melting pt. is lower than that of the plastic material to be used. The material is next injection of blow moulded round the core in a mould of desired shape and, after the material has solidified, the metal core is melted out. ADVANTAGE - The method enables complicated mouldings (and partic. intake manifolds for car engines) to be procueproduced where previously only metal could be used.