Monitoring of resistance spot weld quality using electrode vibration signals

Abstract

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.

A Review of Shunting Effect in Resistance Spot Welding

“…The electrode vibration amplitude curves under shunting conditions at a current of 9.8 kA for three consecutive welds. [10] Rys. 3.…”

“…al. [10], monitoring of resistance spot weld quality including shunting was investigated using electrode vibration signals under abnormal welding conditions. Figure 3 shows the effect of shunting current on the amplitude of vibration measured for multispot distant from each other.…”

“…3. Krzywe amplitudy wibracji elektrod w warunkach bocznikowania prądu zgrzewania o wartości 9.8 kA dla trzech kolejnych zgrzein [10] Fig. 6.…”

Dynamic behavior investigation of spot welding machines and its influence on weld current range by modal analysis

“…Welding current affects directly the electrode vibration and the research results show that electrode vibrations can be used to monitor weld quality, such as no weld, sticking weld, small weld, good weld and expulsion [6].…”

“…The electrode displacement was collected by [6] and the acceleration signals of the upper and lower electrodes using the signal measurement system with both the displacement sensor and the accelerometer, extracted the amplitude curve of electrode vibrations at 100 Hz through a series of data processing, and studied the effect of the welding current and the abnormal welding conditions on the vibration amplitude curve and resistance spot weld quality and the results showed that electrode vibrations can be used to monitor weld quality, such as no weld, ticking weld, small weld, good weld and expulsion, concluding that the accelerometer sensor is better for industrial application because there is no installation interference between sensors and workpieces.…”