HIGH-FREQUENCY HEATING METHOD FOR RACK BAR AND HIGH- FREQUENCY HEATING DEVICE

摘要

PROBLEM TO BE SOLVED: To provide such a high-frequency heating method for rack bars which is capable of simultaneously efficiently hardening the tooth faces and backs of the rack bars without using a direct energization method and forming good hardening layer patterns over the entire peripheral surface of the rack bars and a high-frequency heating device. SOLUTION: A stage for subjecting the rack bar 1 to high-frequency induction heating under the state that the rack bar is held static relative to a high-frequency induction heating coil 19 by using the high-frequency induction heating coil 19 having a pair of main conductors 21a and 21b respectively disposed to face each other on the tooth face 3 and back 4 of the rack bar 1, a stage for further continuously subjecting the rack bar 1 to the high-frequency induction heating under the state that the rack bar is kept rotated relative to the high-frequency induction heating coil by rotating the rack bar 1 around its axis X and a stage for rapidly cooling the entire peripheral surface of the rack bar 1 at the point of the time the entire peripheral surface of the rack bar 1 is subjected to the high-frequency induction heating to a required hardening temperature after the above stage are successively carried out.