| 摘要 |
PURPOSE:To stabilize heat treatment and to save consumption of electric power by connecting and controlling the outputs of plural annealing machines of producing installations for electric welded pipes in accordance with the temp. of the parts to be heated and conveying speeds of the electric welded pipes and the electrical conditions of the annealing machines. CONSTITUTION:While an electric welded pipe P is conveyed in the direction of a blank arrow, its weld heat affected zones are heat-treated with annealing machines 11, 21 which are disposed in tandem. Commercial power sources are converted to high frequencies with frequency converters 12, 22 and electric power is supplied via transformers 12, 23 to the machines 11, 21. Thermometers 14, 24 apply their measurement signals to the output voltage control circuit 12a of the device 12, and the output voltage control circuit 22a, respectively. The circuit 12a changes and controls the output voltage in the device 12 within a prescribed range in accordance with the output of a potentiometer 12b for setting the temp. of the parts to be heated of the pipe P on the down stream side of the machine 11 and the signals of the thermometers 14, 24 as feedback information. The circuit 22 also controls the device 22 similarly to monitor the temps. in the two places, whereby the accuracy of the temp. controlling is improved. If the meters 12b, 12b are set adequately, the utilization efficiency of the power source circuits is improved and electric power consumption is minimized. |
