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

摘要

PROBLEM TO BE SOLVED: To prevent the development of hardening crack of a crank shaft by uniformly applying a high-frequency induction heating to the surface of a pin part of the crank shaft and to restrain the hardening distortion (deformation) to a small degree. SOLUTION: When the pin part 14 rotates a section from a prescribed position (point B) before the pin part 14 passes through a top dead point C to a prescribed position (point D) after passing through the to dead point C according to the rotation of the crank shaft 1, an intermittent heating is preformed to the pin part 14 by intermittently supplying a high-frequency current to a high-frequency induction heating coil 4. Further, when the pin part 14 rotates a section from the prescribed position (point D) before the pin part 14 passes through a bottom dead point A to the prescribed position (point B) after passing through the bottom dead point A, a continuous heating is performed to the pin part 4 by continuously supplying the high-frequency current to the high-frequency induction heating coil 4, and thus, the surface of the pin part 14 having different heating capacity at its each position is uniformly heated.