| 摘要 |
PURPOSE:To form groove parts lengthwise easily even in the surface of a long- sized tube material which has step parts in the middle, by pressing plural rotatable forming rollers against the tube material surface and then running it lengthwise. CONSTITUTION:Plural rotatable forming rollers 2 are pressed against the surface of a tube material 1 wherein groove parts 3 are to be formed at equal intervals so that each rotating surface coincides with the center axis 1 of the tube material 1. Those press-contacting rollers 2 are run in the lengthwise direction of the tube material 1 and grooves 3 are formed in the surface axis direction of the material 1 with rotating circumferential edge parts of the rotating rollers 2. In this case, the tube material 1 is rotated around the center axis A by a specified angle in the middle to easily form numbers of grooves 3 at different intervals. This method facilitates the formation of the groove parts 3 even if there is a step part 4 in the middle of the tube material 1. |
