Plastic pipe and method and apparatus for manufacturing same.

摘要

A method of manufacturing a plastic pipe (C) having a spiral ridge on an outer surface and a flat inner surface, comprising the steps of: [a] supplying a plastic ribbon (A) in a softened state onto a plurality of rotating forming rolls (5) arranged circularly, so that the plastic ribbon is spirally wound around the forming rolls while partially overlapping to be fused with each other; [b] spirally winding an endless forming core belt (12) around the forming rolls in such a manner that the endless forming core belt is sandwiched between the plastic ribbon already wound around the forming rolls and the plastic ribbon newly supplied, thereby providing the resulting plastic pipe (C) with a spiral ridge; (c) cutting the spiral ridge by means of a cutter (13) after the adjacent parts of the plastic ribbon are fused with each other and sufficiently cooled, thereby providing the spiral ridge with a slit (14) extending along it to remove the endless forming core belt (12) from it; and (d) winding a second plastic ribbon (B) in a softened state around the spiral ridge to fuse the second plastic ribbon thereto, thereby sealing the slit (14).