The principle of the work is the electronic tube self-excited oscillator. The power frequency current transform 50Hz into a high-frequency current frequency is 100 ± 20KHz, the high frequency current to form a strong electromagnetic field in quenching inductor, which is heated by the metal parts in the strong electromagnetic field, high temperature due to eddy current and loss hysteresis, and thus the metal parts to be heating heating purpose. Suitable for different process requirements.