Alternating current tungsten inert gas welding process

摘要

PURPOSE:To perform optimum welding in accordance with welding quality required by controlling so as to maintain constant an average value of an output current of each polarity with respect to every frequency of the AC output. CONSTITUTION:In the case of welding, a welding current setter 16 sets a welding current value and further, a frequency setter 9 and an EP period ratio setter 10 set the frequency of the AC output and an EP period ratio, respectively. At the time of welding, a value of a current which is outputted from an output side rectifier 5 and inputted to an output side inverter 8 is detected by a current detector 6 and the detected current value is inputted to an error amplifier 17. The error amplifier 17 compares the current value detected by the current detector with the current value corresponding to the current value set by the welding current setter 16 and a pulse width control circuit 3 is controlled so that the average value of the current value flowing thyroid the current detector 6 is made to the current value corresponding to the welding current value. Namely, regardless of height of the frequency set by the frequency setter 9, the average value of the current value flowing through the current detector 6 is maintained at the current value corresponding to the welding current value.