Monitoring of resistance spot weld quality using electrode vibration signals

Electrode vibrations can reflect resistance spot weld nugget formation, but this has not been widely appreciated so far. Although a displacement sensor can be used to detect the electrode vibrations, it is not suitable for industrial applications for its inconvenient installation and high cost. In this paper, an electrode displacement between two electrodes and acceleration signals from the upper and lower electrodes were measured using a displacement sensor and a dual accelerometer respectively, and the vibration amplitude curves were extracted from the collected signals through data processing and the results showed that they are very consistent. The effect of welding current on an electrode vibration curve monitored using the dual accelerometer was studied, and the results showed that electrode vibrations can be used to monitor weld quality, such as no weld, sticking weld, small weld, good weld and expulsion. Moreover, the monitoring of resistance spot weld quality using electrode vibration signals under abnormal welding conditions, such as shunting, small edge distance and greasy surface, was also performed. This research will provide references for monitoring resistance spot weld quality using the accelerometer method.