SYNTHETIC RESIN PIPE AND EXTRUSION DEVICE FOR MAKING SAME

摘要

A pipe having a substantially square cross section portion and a substantially circular cross section portion are disposed alternately in the axial direction of the pipe. The thickness of the circular portion is set uneven in the circumferential direction. In particular, the thickness of the portions of the circular portion that correspond to the corner portions of the square portion is set larger than the thickness of the portions that correspond to the central portions of the respective sides of the square portions. Accordingly, a pipe having corner portions with increased pressure deformation resistance is obtained. Also, the pipe is capable of being manufactured in a high efficiency manner.