| 摘要 |
<p>PROBLEM TO BE SOLVED: To decrease stresses after cooling and to lessen the deformation quantity after hardening by relieving the plastic deformation during the hardening and heating of a ring gear 1 as annular parts in the case the outer peripheral tooth part of the gear is subjected to a hardening treatment by high-frequency heating. SOLUTION: Both of the outer peripheral tooth part 2 which is the part to be hardened and inner peripheral part 4 which is a nonhardening part of the ring gear 1 are subjected to the hardening treatment by simultaneously heating both of these parts respectively by heating coils 9, 10, stopping the heating to the inner peripheral part 4 when the temperature of the inner peripheral part 4 attains the temperature near the austenite transformation point Al and heating only the outer peripheral tooth part 2 up to hardening temperature, then immersing the gear 1 into cooling oil 13 and simultaneously and uniformly cooling the outer peripheral tooth part 2 and the inner peripheral part 4.</p> |
