Through arc sensing in gas metal arc welding with signature images

Abstract

This work presents a new method for through the arc estimation of welding parameters in gas metal arc welding based on signature images. The method is generally applicable and makes use of a novel data fitting procedure. The work covers unassisted through the arc estimation, without auxiliary techniques such as welding head oscillation. The technique is demonstrated for both pulse and short circuiting welding, with estimation of position relative to an overlap joint and a narrow gap weld, and estimation of the width of a 'V' groove. The accuracy of the technique is affected by how closely the welding signatures match the fitting data and the signature image quality match provides a valuable check which shows when through the arc estimates cannot be relied on. Overall, the results demonstrate that through the arc measurements can have application in specialised situations, although accuracy is ultimately limited by phenomena that affect the arc and are not correlated with the measurement.