| 摘要 |
<p>PURPOSE:To prevent the formation of creases in the vicinity of seams by forming a stage difference having a prescribed height on the outer peripheral surface succeeding to both the edges of the fitted seam, as for a corrugated pipe which is formed by winding a strip steel having a rib bulging out from a standard surface and seams at both the edges, in spiral form, and fitting the seams. CONSTITUTION:A corrugated pipe is manufactured by winding a strip shaped steel which has a plurality (e.g. three) of ribs 2 which bulge out by a height H from a standard surface 1 and has seams 3 (3A, 3B) which can be fitted each other at both the edges, in spiral form, and by fitting the contiguous seams 3A and 3B. In this case, a stage difference 4 which is higher nearly by H/2 from a standard surface is formed on the outer peripheral surface succeeding to the seam 3 of the corrugated pipe, by forming each contiguous spread diameter part 5 on both the sides of each fitted seam 3 of the corrugated pipe. Accordingly, the strength in the vicinity of the seam 3 is increased, and the generation of creases in the vicinity of the seam 3 in the shaping to the corrugated pipe is prevented.</p> |
