Mould cores for moulding hollow rubber articles - with pneumatic disengagement from the static part of core mandrel

摘要

The core mandrel of a mould for making hollow mouldings from elastic material comprises two concentric hollow bodies shaped so that the smaller can more relative to the larger subjected to limits imposed by a conic seat and by a static head which limits the axial parting of the core pieces, e.g. by stopping a lip at the end of the base in the mobile core. The mobile core has an external lip which engages the end of the moulding. As the mobile core is shifted by pneumatic pressure, the moulding is subjected to tension and and then to internal pneumatic pressure via the parting plane of the cores, to ease disengagement of the moulding from the static mandrel. Arrangement is esp. suitable for making bellows or other articles with undulating wall profiles.