Regression modeling and process analysis of resistance spot welding on galvanized steel sheet

The resistance spot welding process of galvanized steel sheet used in the body manufacturing of family car was investigated on the basis of mathematical models. Method of non-linear multiple orthogonal regression assembling design was applied in experiment. The indexes studied in experiment were nugget geometry and tensile–shear strength of spot welds. Furthermore, four process parameters, namely welding current, electrode force, welding current duration and preheat current, and interactions among them were considered as the factors impacting indexes. The mathematical models developed were optimized by means of variance analysis. The experimental results showed that there was a more accurate prediction on nugget size and mechanical properties of spot welds by the models optimized. With these prediction results, the optimization of welding process also was realized by the analysis to the effect of parameters and interactions on the welding quality.