A Comparative Study of Single-Phase AC and Multiphase DC Resistance Spot Welding

Abstract

This paper presents a comparative study of the AC and MFDC resistance spot welding process. Both experiments and finite element simulation were conducted to compare the weld size and energy consumption. The experiments were performed on two identical spot welding machines, one with a single phase ac and the other with a mid-frequency DC weld control. The machines were instrumented such that both the primary and secondary voltage and current signals could be collected for energy calculation. The finite element simulation model was developed to understand the underlying mechanisms of the difference between the ac and MFDC processes. The effect of the current waveform was investigated by using the actual process measurements as an input to the simulation model. It is shown that the MFDC process generally produces larger welds than the AC process with the same root-mean-square welding current. However, this difference is more prominent when the welding current is relatively low. Overall, the AC welding process consumes more energy to make a same sized weld than the MFDC process. The larger the welding current is used, the less efficient the AC welding process will become. The differences between the two welding processes are caused by the contact resistance behavior and the electrical inductance in the AC welding process.

Induced electromagnetic stirring behavior in a resistance spot weld nugget

“…Temperature-dependent material properties and contact properties [7,8,18] were used. The BCs and the material properties were the same for the sinusoidal current input and RMS current input except for the current inputs, i.e., the RMS current input used the setting value I w of welding machine, and the sinusoidal current input used w 2 sin(2π ).…”

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

“…Some researchers have investigated the cause of vibration during a welding process [7] found that there are mechanical vibrations and high current peaks when using alternate current, and the vibrations disappear when using direct current. It indicated that mechanical vibrations are generated by the alternating welding current.…”

“…It is believed that the amount of thermal expansion, melting, and expulsion can be corrected to the slope and magnitude of the displacement curve. A number of control systems have been developed based on maximum electrode displacement or its changing rates [7,12].…”

Performance Analysis of ANN Training Algorithms to Detect the Magnetization Level in the Magnetic Core of a Welding Transformer

“…The resistance spot welding systems described in different realizations [2]- [5], are widely used in the automotive industry. Although the alternating or direct currents (dc) can be used for welding, this work focuses on the RSWS (Fig.…”