| 摘要 |
PURPOSE:To equalize a metallic formation in the same section of a bend pipe by providing a cooling ring on both inside and outside of a pipe to be bent of a bending part of the front of a heating ring so that a cooling speed of the inside and outside surfaces becomes the same, the executing a titled bending. CONSTITUTION:A pipe to be bent A is inserted into the inside of a heating ring 2 connected to a high frequency power source 1 without making it contact to the ring 2, by a feed device, an arm 4 for setting a bend radius, and a guide roller 8. Subsequently, the temperature of a pipe wall of the pipe A is raised to a prescribed working temperature by supplying a high frequency current to the ring 2 from the power source 1. As soon as this temperature rise is started, the pipe A is extruded forward by the feed device 3, rotated round a rotation center 5 by a rotation of the arm 4, and bending of the pipe is started. In that case, in order to keep a width of a hot working area in an optimum state, water, air or mist is blown out from a cooling ring 6 and a cooling ring 7, respectively, and the inside and outside surfaces of the pipe are cooled at the almost same speed. |
