The formed resin abrasive tool body has a certain hardness, strength and heat resistance after heat treatment. This process is called hardening. Hardening is one of the key processes that determines the performance and quality of the resin abrasive tool. The hardening of the resin abrasive tool body generally uses hot air as the heat transfer medium, and electricity is commonly used as the heating energy. The air is heated by the electric heating element and then transferred to the base body for heat hardening. The commonly used electric heating air hardening equipment is chamber hardening furnace.

The original chamber hardening furnace temperature control system uses a relay control system. This system uses hard wiring. Although it has shortcomings such as poor flexibility, low operating frequency of mechanical contacts, and easy damage under continuous operation, the voltage waveform on the load of the system is not distorted and remains a complete sine wave.

At present, most hardening furnace temperature control systems use thyristors or power electronic solid-state relay control systems. These systems have the advantages of high sensitivity, fast switching speed and long life, but the voltage waveform on the system load will change more or less, and there are harmonic components. From an engineering practical point of view, it is necessary to design and develop a new type of control system specifically for the hardening furnace to minimize the impact of power electronic devices on the voltage waveform while retaining its convenient control characteristics.