PRODUCING THERMOPLASTIC ARTICLES, PARTICULARLY WITH POROUS WALLS

摘要

An expander for continuously expanding a pipe made from a thermoplastic material comprises a plurality of spindles 36 spaced about a central axis and arranged to be located within the pipe. The spindles are divergent in a downstream direction and are driven in rotation about the central axis and about their own respective axes by a motor 24. The spindles may each have a helical rib 42 for use in expanding a corrugated pipe.