Step-link shaft superaudio induction quenching method and special induction coil thereof

The invention discloses a step-link shaft superaudio induction quenching method. The step-link shaft comprises a large-diameter shaft and a small-diameter shaft; and a transition round corner is formed between the large-diameter shaft and the small-diameter shaft. The method comprises the following steps: selecting a suitable induction coil according to the large-diameter shaft; packaging the induction coil in a part which needs to be quenched; and rotating the step-link shaft, wherein the input voltage of the induction coil is 380V; the input power of a superaudio induction heating power supply is between 150 and 250KW; and the oscillation frequency of the superaudio induction heating power supply is between 25 and 40 KHZ. The invention also provides a special induction coil of the method. The special induction coil is provided with a bracket, two magnetic conductors and a plurality of groups of coils embedded in grooves of the magnetic conductors; the bracket is provided with an upper conducting surface and