The electric resistance welding time is short and the process is not visible, so during the actual welding process, there will be joint quality of instability caused by the instantaneous voltage fluctuations, current shunt, electrode wear and other factors. Nowadays, the application of resistance welding technology has widespread, so the quality control is extremely important. Over the years, many scholars have proposed various resistance welding quality control methods, below is several mature control method we can apply.

1. Constant Current Control

This method is applied by comparing the detected welding current with the given value, and regulating the firing angle by using its bias swithcing device so as to adjusting the constant current equal to the given value. The key point is how to capture the constant current control current signal. At present, a current collected by the collecting main core coil sensor detects the welding current from the secondary circuit, which directly affects the production level of the constant current control accuracy

2. Dynamic Resistance Control

This method is widely accepted due to its extensive material adaptation and quality fluctuation overcome. The mechanism is the use of the metal being welded volume expansion upon melting, the electrode is displaced and the displacement of the core and the size-dependent, the amount of displacement by the real-time control of the quality of solder joints

3. Parameters Control

Although the use of the above spot welding quality control methods, but rely on any of these control methods are still unable to overcome the quality fluctuation due to various complex reasons. Clearly the use of a single parameter as the control object is not sufficient, some scholars put forward the idea of ??multi-parameter control. Among them, the German scholar Burmeister [7] using fuzzy control method successfully between the electrical and mechanical parameters and welding quality to establish a new relationship model. Foreign companies have also introduced that can achieve multi-parameter control products.