Quantitative Interpretation of Dynamic Resistance Signal in Resistance Spot Welding

Abstract

Dynamic resistance is one of the most common and important signals used to monitor and control the resistance spot welding (RSW) process. However, existing studies on the signal evolution mechanism are limited to qualitative analysis, resulting in an ambiguous interpretation of the formation mechanism for the signal features. In this paper, a collaborative simulation approach was applied for the RSW of bare DP590 steel to obtain high-precision computation of the temperature and potential distributions inside the weld. On this basis, an analytical mapping model between the dynamic resistance signal and the weld profile was developed based on basic physical laws, and the signal evolution mechanism was quantitatively revealed through the model. It was found that the main factors determining the signal evolution trend are average sheet temperature and electrode/sheet contact diameter rather than the nugget growth process. The peak resistance feature was attributed to the bilinear relationship between sheet resistivity and temperature rather than nugget formation. The resistance drop after the peak mainly arose from the increase of the electrode/sheet contact diameter rather than nugget growth. This study can help improve the comprehension of the dynamic resistance signal and the interpretability of some data-driven methods used for RSW quality monitoring and control.

Resistance spot welding defect detection based on vectorized dynamic resistance signal and LightGBM classifier

“…Xing et al [29] categorized the dynamic resistance curve into three phases, while Tan et al [30] divided it into six phases. In 2023, Xia et al [31] developed a finite element model to quantitatively interpret dynamic resistance curves. Generally, the dynamic resistance can be decomposed into the contact phase, the phase of solid metal warming and melting, and the nugget growth phase.…”

Assembly of Portable Spot-Welding Machine

“…The study [7] examines the impact of various welding conditions (such as technological parameters) and adhesive bonding factors (like surface preparation methods, overlap size, and thickness during bonding) on the formation process of hybrid connections. Dynamic resistance plays a crucial role in monitoring and controlling the resistance spot welding process [8,9]. However, limited qualitative analysis has been conducted to understand the mechanism behind signal evolution, leading to an unclear interpretation of its formation.…”

“…However, limited qualitative analysis has been conducted to understand the mechanism behind signal evolution, leading to an unclear interpretation of its formation. To address this issue, [8] study adopts a collaborative simulation approach for bare DP590 steel RSW. This enables us to accurately compute temperature and potential distributions inside the weld area.…”