| 摘要 |
PURPOSE:To avert generation of an arc between electrodes and a material to be heated by detecting the contact resistance between the electrodes and the material to be heated and controlling the energizing current value from the relation between the preset current density at the energizing parts of the electrodes and the contact resistance. CONSTITUTION:The electrodes 2 are pressed to both ends of the steel material 1 to be heated by the actuation of a cylinder 3 and are energized from a power supply 7 to heat the steel material 1. The voltage drop quantity signal from voltage detector 6-1, 6-2, the energizing current from a current detecting part 8, the area of the contact part of the steel material 1 to be heated with the electrodes 2, and the temps. near the contact part and the central part of the steel material from temp. detectors 5-1-5-3 are inputted to an energization controller 9. The controller 9 in the above-mentioned constitution outputs a control signal to the cylinder 3 or a power regulator 7' by the relation between the preset current density in the energizing parts of the electrodes by the steel material 1 to be heated and the contact resistance or the value obtd. by multiplying the contact resistance by the apparent area of the contact area. The generation of the arc in the contact part is thereby prevented and the deformation of the steel material 1 is prevented.
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