Double wall rectangular tube made of polyolefin resin, double wall rectangular tube tube, and cable line method for double wall square tube tube

摘要

Problem to be solved: to provide a cable line method to a conduit of a double wall square tube made of a polyolefin resin, which can easily conduct a wire line operation, a tube of double wall square wire tube, and a double wall square cable tube using the same.A plurality of large diameter portions 3 and small diameter portions 5 are alternately formed in the outer circumferential surface of the double wall angular tube tube 1 alternately in the tube axis direction of the outer tube 7.A cylindrical inner pipe 9 is disposed inside the outer tube 7.The inner circumferential surface of the small diameter portion 5 of the outer tube 7 and the outer peripheral surface of the inner pipe 9 are fused together to be united.At a position corresponding to the large diameter portion 3 of the outer tube 7, an annular space 19 having a predetermined shape is formed between the outer peripheral portion and side wall portion of the large diameter portion 3 of the outer tube 7 and the outer peripheral surface of the inner pipe 9.The inner pipe 9 disposed at a position corresponding to the large diameter portion 3 of the outer tube 7 is formed with an enlarged diameter portion 37 which is slightly expanded toward the central portion in the tube axis direction of the large diameter portion 3.The enlarged diameter portion 37 is periodically formed at a predetermined interval in the tube axis direction across the small diameter portion 5.Diagram