| 摘要 |
PURPOSE:To prevent the wall-thickness deviation of a pipe by moving the bending part of a pipe stock fixed in a cantilevered state as well as parallelly moving its free end-face so that its both end-faces are always parallel to each other and its total length is constant. CONSTITUTION:One end of a pipe stock 10 is fixed by a jig 11a placed at the fixed side and its other end is restricted by a jig 11b placed at the movable side. Further, a heating device 14 and a pusher 12 are provided to the pipe 10. The vicinity of jig 11a is first heated at a prescribed temperature, and the heating part is pressed in the radial direction by the pusher 12. Next, the jig 11b is moved upward as well as advanced to the position P2 so as not to change the total length of pipe 10. Then, the pipe 10 is worked by moving rightward the device 14 and the pusher 12 while always keeping both end-faces of the pipe 10 parallel to each other by the jigs 11a, 11b. In this way, the wall thickness of pipe 10 is made uniform through its whole body, because the pipe 10 is prevented from producing tension or compression at its both inner and outer peripheral sides. |
