Plastic drain pipe and apparatus for producing the same

Abstract

A synthetic plastic drain pipe comprising a continuous pipe of plastic material having transverse, angular or helical corrugations, said pipe having openings for the entry of water, said openings being disposed in said pipe at regular repeating intervals between corrugated lengths of pipe at least at every 20 cm, preferably 30-50 cm, said pipe being free of any opening between said intervals; an apparatus for producing such a synthetic drain pipe, particularly a pipe having distinct portions of general cross section wherein on said portions there are longitudinally running grooves through which there are disposed openings, said apparatus comprising an extruder having an extrusion head, said extrusion head having a generally annular opening defined by a generally circular die disposed about a generally circular mandrel, said apparatus having in general axial alignment with said opening a pair of endless traveling means in the form of a mold train, each of which traveling means carries cooperating mold halves which are in facing relationship generally axial of said openings and joined to define a mold cavity, means for moving said traveling means, means for exerting a partial vacuum on the contents of said mold cavity, some of said molds having grooves to form transversely corrugated pipe lengths of synthetic plastic extruded through said opening, and some of said mold halves having longitudinally running grooves which form longitudinally running grooves in a plastic pipe extruded through said opening.

Dependencies are inferred from the claim text.