| 摘要 |
PURPOSE:To concentrate locally the effect of increasing a wall thickness and to increase locally the wall thickness of a bar-shaped material by cooling quickly the heating part of the bar-shaped body right after passage of a high frequency induction heating coil. CONSTITUTION:A heating coil 4 is moved to a desired position of a pipe 1 to heat locally the pipe 1 and at the same time a gripping jig 2a is moved in an arrow direction by hydraulic mechanisms 3, 3 to apply an axial compressive force on the pipe 1. A swaged part 1a which is increased to a desired wall thickness and is increased in the outside diameter is worked and after the end of heating, the coil 4 is moved and a coolant spraying mechanism 5 is positioned over the part 1a to cool quickly the part 1a, thereby stopping said part at the prescribed wall thickness and increasing locally the wall thickness. If the pipe 1 right after the passage through the coil 4 is quickly heated by moving the mechanism 5 in an arrow direction in synchronization with the movement of the coil 4, the wall thickness is increased over the prescribed length. |
