METHOD FOR REMOVING UNBALANCED HEAT OF METAL TUBE

PURPOSE:To uniformly induction heat the whole metal tube, by moving a core from the standard position to the part of the metal tube causing low temp. unbalanced heat, and compensating positive and negative temps. to low and high unbalanced heat parts respectively. CONSTITUTION:Plural inlet side thermometers C are arranged between a heating coil B and an unbalanced heat removing apparatus A to detect temp. distribution in circumferential direction of the metal tube M. Unbalanced heat part in circumferential direction of the tube M is operated by an arithmetic unit 20 from the detected temp. signal and moving velocity, etc., of the tube M. Set value operated by optimum control models 21-24 of the unit 20 is inputted to a core gap controller part 25. Standard positions of respective cores 7-10 are set in the part 25, and the core at arbitrary part corresponding to low temp. unbalanced heat part is advanced. Inversely, the core is retreated to high temp. unbalanced heat part. By the movement control of the cores 7-10, unevenness in circumferential direction of metal tube in inlet side temp. is dissolved.