Device for injection moulding tubular preforms made of a thermoplastic

摘要

The tubular preform is injection moulded in an injection mould whose initially axially reduced injection cavity is progressively enlarged in the direction of the axis of the preform in step with its filling by the injected thermoplastic until a moulding cavity is obtained which corresponds to the volume and to the shape of the preform to be produced. To this end, the injection mould comprises external die-halves and a central core, which can be moved in relation to each other in the direction of their common lengthwise axis during the injection moulding cycle.