| 摘要 |
A method for straightening a tube by using an asymmetric roll, which has different diameters D1 (exit side), D2 (entry side) at relative maximum diameter portions, left and right roll shoulder portions, as a straightening roll of a straightener, wherein the roll shoulder having a smaller diameter is disposed to be located on the tube entry side. The straightening roll used therefor comprises roll shoulders 3a and 3b and a roll barrel portion 4, in which D1 > D2 and 0.004 ‰¤ (D1 - D2)/d ‰¤ 0.2 (d: outer diameter of tube to be straightened) are satisfied. Further, an aspect of the invention may define radii of curvatures of entry-side and exit-side shoulder potions in a section of the roll cut along a plane including the roll central axis, or a curve representing an outer surface of the roll barrel portion. This roll can suppress the occurrence of leading-end deformation of a tube end portion during the straightening of the tube, thereby achieving enhanced straightening effects. |
