| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve such a problem that, in a conventional manufacturing method and a crushing equipment for a welded pipe, since a portion with an increased wall thickness is separated from an edge side face so that the amount of change in the thickness of the edge side face is small, the effect of a poor shape of an edge part to the thickness at a boundary portion between a weld bead and a base material part remains, so that the difference between the thicknesses of the boundary portion and of the base material part is made large. <P>SOLUTION: In the manufacturing method and the crushing equipment for a welded pipe, before forming an open-pipe, a notch-shaped step 30 is formed on the central part along the thickness direction of an edge side face 3a of a material steel strip 3 by pressing a stepped roll 41 against the edge side face 3a, and then the thickness of the edge side face 3a is increased by forcibly spreading the step 30. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
