METHOD AND DEVICE FOR HARDENING BY HIGH-FREQUENCY INDUCTION HEATING

摘要

PURPOSE:To harden the entire part of a tooth part with good accuracy in the stage of heating the tooth part of a gear by supplying low-frequency electric power to a heating coil when the specified position of the tooth part is below the prescribed temp. and changing over the same to high-frequency electric power when said position is above the prescribed temp. CONSTITUTION:An electric motor 1 is driven and a rotating table 3 on which the gear 2 to be hardened is imposed is rotated. A set signal of heating electric power is supplied from a control device 7 to a high-frequency power source device 6 and a change-over device 5. The heating frequency is selected low and the output power is supplied at the frequency controlled by the power source 6 via the device 5 to the heating coil 4. The temp. increasing state is inputted via an optical sensor 8a and a temp. sensor 9 to the device 7 when the temp. in the tooth part of the gear 2 begins to increase gradually. The device 6 changes over the low frequency to the high frequency to decrease gradually the heating electric power when the temp. of the tooth part attains the prescribed temp. The hardening is executed by the ejection of the cooling liquid, etc., after such temp. control is executed until the heating ends.