METHOD FOR CONTROLLING OUTPUT OF POWER SOURCE FOR CONSUMABLE ELECTRODE AC ARC WELDING

摘要

PURPOSE:To improve welding quality by detecting the quantity of charge during an arc period of time at the time of straight polarity and at the time of reversed polarity and changing over the polarity when a set value is attained and stabilizing the polarity ratio as desired. CONSTITUTION:In a reversed polarity welding state, a selector circuit 13 selects the charge set value VQRP and a charge detection circuit 10 integrates a welding current 1a and detects the quantity of charge at the time of reversed polarity. When a wire comes into contact with base material and shifts to a short circuit, the output of a short-circuit shift inversion circuit 7 of the changed to an L level and the charge detection circuit 10 stops an integral action and holds the rate V2 of integration. When an arc is again generated and an integration value of the charge detection circuit 10 is made to V2V1, the output of a comparator 14 is made to an L level and the output of the selector circuit 13 is fixed on zero level. At the same time, the charge detection circuit 10 is reset and the integration value V2 is attenuated. When the integration value is made to V1V2, the comparator 14 is made to an H level and the output of a flip-flop circuit 15 is inversed and changed over to a straight polarity welding state. The selector circuit 13 selects the charge set value VQSP which is sent out to the comparator 14 and the straight polarity welding is performed till the integration value is made to V2=V1=VQSP.