| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent quenched crack in a fillet part by satisfying quenched hardening layers formed at a columnar part, a round part and a thrust part in a pin part and in a journal part of a crank shaft. SOLUTION: This hardening-cooling method is performed by laying an induction heating coil 1 on the columnar part (121) in the pin part and the journal part (e.g. 120) of the crank shaft 100 and cooling the pin part and the journal part with main cooling means 7, 8 after induction-heating the columnar part, the fillet round part and the fillet part (125) while following to the rotation of the crank shaft 100 to harden by quenching and cool their surfaces. Auxiliary cooling means 15 of the main cooling means 7, 8 are fixed to this induction heating coil 1, and at the time of cooling, cooling liquid is jetted directly to the fillet round part and the fillet part from jetting holes of the auxiliary cooling means 15 to cool them, and to in the fillet round parts and the fillet part having thermal capacity different from the thermal capacity of the columnar part, the uniformized hardened layers with the hardened layer formed in the columnar part, are formed.</p> |
