JPS6422473A - Welding starting point detecting system for automatic welding equipment - Google Patents

Abstract

PURPOSE:To detect a welding starting point with high accuracy at a high-speed action by automatic welding equipment by separating the large welding current change taking place at the time of passing the joint face into each current change at the time of starting the welding and during welding and allowing a control point of the welding torch tip to attain said welding starting point. CONSTITUTION:Since the distance between a feeding chip 1 and base metal at a point A of an upper plate X to an upper plate edge point C is fixed, after the unstable transfer at the time of generating an arc, a stationary transfer state continues. Then, since the distance between a feeding chip 2 and the base metal from the point C is lengthened by for the plate thickness BC of the upper plate X, the stationary short- circuit transfer cannot be carried out. As a result, after attaining the point C, in the course of time until a wire 6 is extended by the lengthened distance to a chip 3, after the lapse of sufficiently long time than the usual arc section, the short-circuit transfer is again attained. Then, since the short-circuit again takes lace and a smoothed value of a current starts to increase, a point to change from decrease to increase takes place there. This characteristic welding current change is caught to detect the welding starting point.