| 摘要 |
In performing cold rolling on a seamless pipe as a mother pipe, it is possible to inhibit the generation of metal chips from the end portions of the mother pipe, and to prevent the formation of indentations therein that may be caused by the metal chips to thereby provide good surface appearance. This is made possible by using a mother pipe (1) having end portions at the cold rolling starting side and finishing side that have been R-chamfered, at each outer edge and at each inner edge, such that (T0 - T1) / 2 ‰¤ R ‰¤ T0 / 2 is satisfied, where R is a radius (mm) of the R-chamfer on the outer edges and the inner edges of the end portions, T0 is a wall thickness of the mother pipe, and T1 is a wall thickness of the pipe after cold rolling. |
