Through arc sensing for reciprocating wire feed gas metal arc welding

Abstract

An arc sensor for reciprocating wire feed gas metal arc welding was developed to detect the torch height and track weld joints. The welding voltage waveform was adopted for the characteristic signal because the welding current remains almost constant with a change in the contact tip-to-workpiece distance. During reciprocating wire feed gas metal arc welding, the voltage waveform changes in an inherently complicated but periodic manner. After recognizing the voltage waveform pattern, the voltage characteristic for each phase was analyzed for arc sensing, and it was revealed that the short-circuit and cycle voltage characteristics were good estimators for torch height sensing. The dynamic arc sensing characteristics for reciprocating wire feed gas metal arc welding were investigated and found to be similar to those of a conventional constant voltage welding system. The seam tracking capability was evaluated by using the voltage integration difference method with transverse torch weaving. The voltage integration difference showed a linear relationship with the offset distance, and the reliability of the joint tracking sensor could be increased by using the moving average algorithm.