To provide a method for manufacturing a large caliber thick-walled polyethylene pipe having uniform strength without causing the resin sag from the inner surface of the pipe or the cross-sectional flattening deformation of the pipe.
The outside surface of the formed and solidified polyethylene pipe P1 is preliminarily heated and melted, and molten polyethylene is annularly extruded from the discharge cap 10 of an extruder 3 to coat the heated and melted outside surface of the polyethylene pipe P1 and integrally welded to the outside surface of the polyethylene pipe P1 to form a thick-walled polyethylene pipe P. It is more suitable to evacuate the space formed before the molten surface of the polyethylene pipe P1 and discharged molten polyethylene are closely bonded.
KAWANO SHOJI
SATO SHINGO
Takashi Noguchi
Kazuhiko Saishita
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