| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that it is difficult to decrease welding defects by a traditional technology to a level which sufficiently satisfies quality requirements of electric weld steel pipe used in a severe environment. SOLUTION: The welding system for electric welded pipe comprises a work coil 2 to perform high frequency heating on a work 10 (which is a metal strip in a raw material stage but becomes a pipe after electric welding), a squeeze rolls 5, 5 to perform pressure welding, a high speed camera 6 which can perform a consecutive photographing for more than 10 ms at a shutter speed of shorter than 1/200 second in the proximity of a welding point 3 of the work. Based on the images taken by the high-speed camera, an image processing apparatus 100 to judge deviation between a narrow aperture zone length L, which is obtained by measuring a length of a narrow aperture zone 4 from a weld point 3 to V convergence point 7, and a designated range (F+A1, F+A2), which is based on a function F(t, d, v), wherein t is thickness of metal strip, d is outside diameter of pipe, and v is welding speed, and a control unit 110 to adjust power supply amount to the work coil depending on these judgments, are also included. COPYRIGHT: (C)2010,JPO&INPIT
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