High-frequency hardening apparatus

A high-frequency hardening apparatus comprising:

• an induction heating coil that includes a U-shaped portion that sandwiches a leading edge of a turbine blade, a pair of linear portions that sandwiches the turbine blade, and a connecting portion that connects the U-shaped portion and the linear portions to each other on a convex side and a concave side of the turbine blade;
• a temperature detection unit that detects a temperature in a first range of the leading edge of the turbine blade in a vicinity of the induction heating coil in a non-contact manner;
• a moving mechanism that moves the turbine blade and the induction heating coil relative to each other in a blade height direction of the turbine blade;
• an electrical current supply unit that supplies a high-frequency electrical current to the induction heating coil;
• a control device that includes an electrical current controller, the electrical current controller controlling a magnitude of the high-frequency electrical current from the electrical current supply unit based on a detection value of the temperature detection unit such that the detection value does not exceed a predetermined temperature;
• and
• an alarm temperature detection unit that is provided separately from the temperature detection unit and that detects a temperature distribution in a second range, the second range including the first range in which the temperature detection unit detects the temperature of the leading edge, the second range being wider than the first range,
• wherein the electrical current controller is configured to issue an alarm in a case where the temperature distribution detected by the alarm temperature detection unit includes a value higher than a predetermined alarm threshold value.