| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a corrugated pipe to facilitate watertight connection and to provide a method to simply and high-efficiently manufacture the corrugated pipe. SOLUTION: A plastic beltlike substance 2 is spirally wound around the crest part 11 of a plastic corrugated pipe body 1 provided alternately with helical crest part 11 and root part 12 and thermally fused to produce a corrugated pipe. The belt width of a belt like body 2 is expanded in a manner to extend over two crests at the two end parts of the corrugated pipe body 1, and an outer cylinder 20 substantially freed from an uneven surface is formed, and at one end or the two ends of the outer cylinder 20, a gap between the corrugated pipe body 1 and the outer cylinder 20 is closed. In a so formed corrugated pipe, the plastic belt-like substance is wound around a mandrel to continuously form the corrugated pipe body. As operation to expand the belt width of the plastic beltlike substance and operation to restore the belt width to an original state are repeated, winding is effected to non-continuously form the outer cylinder, and manufacture is carried out by a method to cut the central part of the outer cylinder.</p> |
