Parameters Monitoring And Optimal Designing For Resistance Spot Welding

Signal acquisition and feature extraction are the premise for quality control in resistance spot welding, while the reasonable parameters are assurances for good solder joint quality. In the process of welding, current, voltage and dynamic resistance are closely related to the formation of solder joint. Therefore this paper has some research about some technique of signal acquisition and feature extraction for resistance spot welding.Firstly, the technique of signal acquisition is studied in this paper. The SML series big electric current sensor is selected for current measurement. The voltage acquisition is accomplished by wires connected at the upper and lower electrodes.Secondly, on the basis of signal acquisition, the relationship between the solder joint quality and the welding parameters is analyzed. When spatter occurs in welding process, it is found that voltage signal waveform changes in the time domain, which main performance is the cycle amplitude fluctuates significantly. The RMS current signal curve heightens obviously on the spatter occurred moment. So, the welding process signals can be used as the basis for welding defect discrimination. By analysis of signal in the frequency domain, it is found that signals characteristics in the frequency domain are not obvious. Therefore, the extraction and analysis of signal characteristics will be focused in the time domainFurthermore, the cause common defects in welding process are analyzed. In order to prevent the defects, the reasonable parameters are the most important condition, additionally, the well technical factors are very important too.Finally, in order to study the best welding parameters for particular material, with laboratory conditions, for 1.0mm thick low carbon steel, orthogonal test is designed. The variance analysis is done for experimental results. According to the results of variance analysis and main effect of the shear strength, the best combination of the parameters is selected. The selected parameters are proved very good by experiment.