Abstract: A consumable electrode type arc welding method for generating arc between a plate-shaped work and a welding wire by a mixed shield gas including argon gas to weld the plate-shaped work, includes: making a state of reverse polarity in which the polarity of the welding wire is positive at the welding start time, and switching at least once to a state of positive polarity in which the polarity of the welding wire is negative.

Abstract: A consumable electrode type arc welding method for generating arc between a plate-shaped work and a welding wire by a mixed shield gas including argon gas to weld the plate-shaped work, includes: making a state of reverse polarity in which the polarity of the welding wire is positive at the welding start time, and switching at least once to a state of positive polarity in which the polarity of the welding wire is negative.

Abstract: An arc welder comprising: a rectifier circuit 2 which rectifies an alternating current 1 to a direct current; an inverter circuit 3; a transformer 4; a second rectifier circuit 5 which rectifies an output of the transformer 4 to a direct current; and a first reactor 6 which is connected to the second rectifier circuit 5. The arc welder further has a current circuit 10 which is connected in parallel to the second rectifier circuit 5 with a reactance that is larger than the reactance of the first reactor 6.

Abstract: An arc welder comprising: a rectifier circuit 2 which rectifies an alternating current 1 to a direct current; an inverter circuit 3; a transformer 4; a second rectifier circuit which rectifies an output of the transformer 4 to a direct current; and a first reactor 6 which is connected to the second rectifier circuit 5. The arc welder further has a current circuit 10 which is connected in parallel to the second rectifier circuit 5 with a reactance that is larger than the reactance of the first reactor 6.

Abstract: An EP output voltage to be outputted during a period of EP polarity is set so that a welding current becomes equal to or lower than a critical current level, and an EN output voltage to be outputted during a period of EN polarity is set at a level lower than the EP output voltage. This makes it possible to substantially equalize a wire melting rate in the period of EN polarity and that in the period of EP polarity with each other. Even at such a short arc length as causing frequent short circuiting, gas-shielded AC arc welding making use of a consumable wire can be still performed stably so that high wire melting rate, shallow penetration, convex weld reinforcement and the like, which are characteristic features of AC welding, can each be set selectively at a desired level or in a desired shape depending on the application.

Abstract: A pulsed arc welding apparatus includes a short circuit detecting circuit for detecting a time during which a short circuit is being produced by melting a consumable electrode across a consumable electrode and a base metal, a comparison circuit for comparing an integrated value or a mean value of short circuit generating time detected by the short circuit detecting circuit with an optional set value, and a control circuit for controlling either one of the supply time of the pulse current and the base current supply time in accordance with the result of comparison by this comparison circuit, thereby to control the arc length.

Abstract: A consumable electrode gas shielded AC arc welding method and an apparatus to practice the method applies alternating current across a consumable electrode and a base metal. During a first period, the electrode is positive and a current of a first level higher than a specified critical level is furnished. During a second period, the electrode is kept positive and current is reduced to a second level lower than the first level. During a third period, the electrode is kept negative at a third current level. These periods are periodically repeated. If during the frist period, the arc voltage drops below a predetermined voltage, current of a fourth level higher than the first level is furnished until the arc voltage exceeds the predetermined level.

Abstract: In a consumable electrode gas shielded arc welding system, alternating current power is applied across the electrode and the base metal. The period during which the electrode is kept negative is varied to correspond to the electrode feeding rate. In addition, the levels of the output power during the negative and positive periods are individually set.