AUTOMATIC DETECTION OF BURN-THROUGH IN GMA WELDING USING A PARAMETRICMODEL

This paper addresses the problem of automatic detection of burn-throug h in weld joints. Gas metal are (GMA) welding with pulsed current is u sed, and welding voltage and current are recorded. As short-circuiting s are common between the welding electrode and the work piece during b urn-through, a short-circuit detector is developed to detect these eve nts. To detect another specific characteristic of burn-through-a broad band long-lasting voltage component-this detector is combined with a s quare-law detector. This second detector is based on a non-linear modi fication of an autoregressive model with extra input (ARX-model) of th e welding process. The results obtained from this compound detector in dicate that it is possible to detect burn-through in the welds automat ically. The work also indicates that it is possible to design an on-li ne monitoring system for robotic GMA welding. (C) 1996 Academic Press Limited