| 摘要 |
In the present invention, when cold rolling is performed with a seamless pipe as an element pipe, an element pipe (1) is used for which an R-chamfering process is performed on the outer surface and the inner surface of the end parts on the cold rolling starting side and the cold rolling ending side so as to satisfy (T0-T1)/2 = R = T0/2. Thus, it is possible to prevent the generation of cut pieces from the end parts of the element pipe and to prevent the formation of indentation flaws caused by the cut pieces, and thus to beautify the surface. Here, R is the diameter (mm) of the R-chamfering applied to the outer surface and the inner surface of the end parts, T0 is the wall thickness of the element pipe, and T1 is the wall thickness of the pipe after cold rolling. |
