Mould for e.g. tyres, with holes to allow venting of air only

摘要

A mould, for the prodn. of rubber or plastic articles, and tyres in partic., has a number of holes through its wall and these are so small that the moulding material is not pressed through them.Pref. the example shown is the section of a mould wall, with atmosphere on the outers side (a). The interior face of the mould wall can have webs; air enclosed between a web and wall can escape through bores which lead out to atmosphere. The inner end of the bore is covered with a small block of sintered metal, whose inner face is flush with the mould interior. The porous body of the sintered metal provides a smooth face but has a large number of very fine pores for air (e.g. pressurised) to escape.