Weld-Quality Prediction Algorithm Based on Multiple Models Using Process Signals in Resistance Spot Welding

Sehyeon Kim,Young-Min Kim,Jiyoung Yu,Munjin Kang,Insung Hwang,Dong-Yoon Kim

doi:10.3390/met11091459

Abstract

An efficient nondestructive testing method of resistance spot weld quality is essential in evaluating the weld quality of all welded joints in the automotive components of a car body production line. This study proposes a quality prediction algorithm for resistance spot welding that can predict the geometrical and physical properties of a spot-welded joint and evaluate weld quality based on quality acceptance criteria. To this end, four statistical models that predict the main geometrical and physical properties of a spot-welded joint, including tensile shear strength, indentation depth, expulsion occurrence, and failure mode, were estimated based on material information, dynamic resistance, and electrode displacement signals. The significance of the estimated models was then verified through an analysis of variance. The prediction accuracies of the models were 94.3%, 93.4%, 97.5%, and 85.0% for the tensile shear strength, indentation depth, expulsion occurrence, and failure modes, respectively. A weld quality evaluation methodology that can predict the properties of a spot-welded joint and evaluate the overall quality requirements based on authorized welding standards was proposed using the four statistical models.

Highlights

A is the maximum point of the linear variable displacement transducer (LVDT) electrode displacement waveform, feature point B
A weld quality prediction model was estimated using a polynomial regression model and logistic regression model based on the parameters of the material information and welding process signal information
The results of this study can be summarized as follows: (1) Features were extracted from the material information, electrode displacement waveform, and dynamic resistance waveform as inputs to the weld quality prediction models for expulsion occurrence, failure mode, indentation depth, and tensile shear strength

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Resistance spot welding is the main joining method used in the assembly of automobile parts. This technique has the advantage of high productivity compared to other welding processes. As the welded parts used in car bodies directly affect the stiffness and collision safety of the vehicles, it is important to improve the quality and maintain the uniformity of the weld. The tensile shear strength, indentation depth, expulsion occurrence, and failure mode are properties of a welded joint that affect the quality of welded parts [1,2,3,4]

Methods

Results

Conclusion