Process of forming plastic tubing which is partially corrugated

Abstract

Abstract Continuous formation of partially transversely corrugated plastic tubing by extruding a tube of thermoplastic material; passing the tubing, while still in thermoplastic forming condition, through a mating mold half assembly in which each set of mold halves are connected together in an endless fashion and wherein some of the mating mold halves have transverse corrugation molding means therein and some of the mating mold halves are smooth in so far as their molding surfaces are concerned; closing the mold halves about said tubing; simultaneously conveying the endless mold half assemblies and the endless thermoplastic tubing in molding relation to each other at the same rate along a old path; applying a vacuum to the outside of said thermoplastic tubing along said mold path through said mold halves thereby drawing said thermoplastic tubing against the smooth molding surfaces of the smooth mold halves and into the transverse corrugated molding surfaces of the corrugated mold halves; and opening said mold halves from about said tubing after said tubing has cooled to below its thermoplastic forming temperature.

Inventors

• 👤 W Hegler

Bibliographic Details