Internal- or external screw core extraction unit used with pressure injection moulding machine

摘要

This new unit extracts the threaded core used in making plastic, pressure injection-moulded articles with screw threads (16). The thread core may carry external- (15) or internal threads. It is connected to a drive shaft moving back and forth along the linear ejection path (c). The core/shaft connection is solid in respect of rotation, tension and thrust. The shaft has an external lead screw (L) matching the core thread in pitch, and engaging a fixed internal thread (G). An elongate, spline spur gear (28) is fastened to the shaft, engaged by a drive gear (29) at all times during longitudinal shaft movements. In this new design, the spur gear (28) is the sun wheel of an epicyclic drive (P), with at least three driving planet wheels (29).