METHOD OF AND APPARATUS FOR CONTROLLING WALL THICKNESS IN EXTRUDED TUBULAR SYNTHETIC-RESIN BLANK

摘要

A mold has a core surrounded by an outer sleeve which defines with the core an annular axially extending passage. An adjustment element in the form of a ring or sleeve is displaceable in this passage so as to vary the radial dimension of a tubular blank that is extruded from the outlet end of the passage. The adjustment ring or sleeve may be elastically deformable by means of hydraulic cylinders or screws so as to create the desired thickness at the desired location, and may even be displaced during operation of the apparatus so as to vary the thickness of the blank from one region to another in the direction which it is extruded.