| 摘要 |
PURPOSE:To harden stably the ring gear tooth part of a flywheel formed integrally with a body and a ring gear part without generation of strain and quenching crack by hardening said tooth part under the heating conditions adjusted so as to decrease heat capacity. CONSTITUTION:A cast iron flywheel formed integrally with a ring gear part on the outside circumferential part of a flywheel body part is hardened by high-frequency hardening by which the ring gear tooth part is hardened. The conditions for frequency, power density, heating time, etc. are adjusted to make the heat capacity in the high-frequency heating part substantially smaller than the heat capacity of the flywheel in this stage. The ring gear tooth part treated in such a way is hardened by the self-cooling after high-frequency heating. The ring gear tooth part is subjected to hardening with stable hardening quality by the above- mentioned method without generating strain and quenching crack of the flywheel. |
