| 摘要 |
PROBLEM TO BE SOLVED: To expand a metal tube without thinning by approaching one of rotation holding bodies to the other in a state in which the rotation around the axis is applied to the metal tube on the straight line held with a pair of rotation holding bodies facing each other, biasing to the direction crossing to the axis and then eliminating the bias to restore to the original state. SOLUTION: A drive rotation part 5 and a driven rotation part 14 are arranged so that the axis of their holding cylinder 7, 20 are coaxially positioned. Next, after a metal tube is inserted into the chuck sleeve of the drive rotation part 5 and the driven rotation part 14 and is held, the interval between the chuck sleeves 9, 21 is set to a prescribed interval by a feed device 23. Next, the metal tube is pressed in the axial direction by a pressing device 32, a motor is operated, and then the metal tube held between the chuck sleeves 9, 21 is rotated. Successively, the metal tube is bent by a bias device. The part of the metal tube between the chuck sleeve part is compressed and expanded by these pressing, rotation, bending, while continuing rotation, pressing, the bias device is restored to the original state.
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