| 摘要 |
PURPOSE:To permit an adequate heat treatment even if a weld zone is fluctuated by quick cooling in a fresh direction by providing a mark detector on the down stream side of a cooling part as well and controlling the titled position by the results of the detection with the two detectors at the time of heating the weld zone the quick cooling and reheating the weld zone. CONSTITUTION:The mark C put on the side face of an electric welded pipe 1 transferred in a direction G at the start of the heat treatment is detected by the upper stream side mark detector 5, which the fluctuation value of the weld zone A by the twist of the pipe 1 is detected. Since this moving amt. is proportional to the transfer distance of the pipe 1, the above-mentioned fluctuation value is substd. in the proportion equation and is calculated. The predicted fluctuation position (d) of the weld zone A on the down stream side of the detector 5 is calculated and inductors 7, 7 for heating are moved to the adequate position in correspondence thereto. Three sets of the inductors 9 for tempering, etc., and the down stream side mark detectors 10 are moved onto the positions (d) respectively corresponding to said positions. The pipe 1 is then cooled by a cooling shower 8. The mark C deviates from C1 as well when the weld zone A is fluctuated again by the secondary twist at this time. This deviation is detected by the detectors 10 and the inductors 9 are positioned directly above the actual weld zone A.
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