| 摘要 |
In the metal tube-twisting method of an embodiment, when a metal tube (5) is conveyed by a depression-forming roll set (4a), a standard roll set (4b), and a twisting roll set (4c) in said order, the metal tube (5) is twisted by: pressing the metal tube (5), which has a substantially circular cross-section, toward the tube interior using the depression-forming roll set (5a) to form depressions (53); bringing the standard roll set (4b) into contact with the metal tube (5) from specified directions; and providing the twisting roll set rotated in the tube circumferential direction from the contact surfaces of the standard roll set (4b) according to the desired twisting angle with respect to the pitch from the standard roll set (4b) in the tube axis direction, and pressing the metal tube (5). |
