Abstract: An arc welding machine which is capable of feeding a welding wire stably at low and a high speeds. The arc welding machine includes a welding wire feed rate setting section; a welding wire feed motor; a welding wire feed motor driving section which supplies electric power required for driving said welding wire feed motor; and a welding wire feed control section which uses, as a control frequency, a frequency other than a frequency of an input power supply or a frequency twice as high or three times as high, or a wire feed control section which selects a low control frequency for feeding a welding wire at a low rate and a high frequency for feeding the welding wire at a high rate, or a welding wire feed control section which selects a high control frequency for feeding the welding wire at a low rate and a low frequency for feeding the welding wire at a high rate.

Abstract: An arc welding machine comprises an output control circuit which produces an arc output in accordance with output control signal, an output detection circuit which measures the state of arc output and produces a feedback signal indicative of the output arc state, and a fuzzy inference control circuit which introduces the feedback signal, produces a welding current waveform and welding voltage waveform required to produce the optimal arc state based on the fuzzy inference, and delivers the resulting waveforms to the output control circuit as the output control signal.