HIGH-FREQUENCY INDUCTION HARDENING METHOD FOR PIN PART OF CRANK SHAFT

摘要

PROBLEM TO BE SOLVED: To provide a high-frequency induction hardening method of a pin part of a crank shaft by which the development of hardening crack of the crank shaft can be prevented by uniformly applying the high-frequency induction heating to the surface (portion to be hardened) of the pin part of the crank shaft, and also, hardening distortion (deformation) can be restrained to a small degree. SOLUTION: When the pin part 14 of the crank shaft 1 passes through a top dead point position C, high-frequency current having the highest frequency is supplied to a high-frequency induction heating coil 4, and when the pin part passes through a bottom dead point position A, high-frequency current having the lowest frequency is supplied to the high-frequency heating coil 4, and thus, the surface of the pin part 14 having different heating capacity in its each position is uniformly heated.