Arc welding apparatus and arc welding method

An arc welding apparatus comprising:

• a power supply that supplies welding power to a path including a welding wire and a base material;
• a wire feeder that feeds the welding wire at a wire feeding rate in a forward direction toward the base material and in a reverse direction away from the base material;
• and
• a controller that controls the power supply and the wire feeder such that a plurality of unit welding steps are performed, each of the unit welding steps including a short circuit stage in which the welding wire and the base material are short-circuited and an arc stage in which an arc is generated between the welding wire and the base material,
• wherein the arc stage comprises a maximum forward feeding period in which the wire feeding rate is kept constant at a maximum forward feeding rate in the forward direction,
• wherein, when a first transition period is defined as a period beginning from a starting point of the arc stage and ending at a starting point of the maximum forward feeding period, and an average welding current is defined as an average value of welding current during the short circuit stage and the arc stage, wherein the starting point of the arc stage starts at a moment the wire feeding rate changes from a maximum reverse feeding rate toward zero,
• the controller is configured to set, within the first transition period, a current suppression first period during which welding current is made smaller than the average welding current,
• the welding current is configured to decrease during the first transition period after the current suppression first period,
• when a length of the first transition period is TO and a length of the current suppression first period is T1, 0<T1/T0≤0.8,
• the controller is configured to set, immediately before the first transition period, a maximum reverse feeding period during which the wire feeding rate is maintained at the maximum reverse feeding rate, and also set a current suppression preliminary period during which the welding current is made smaller than the average welding current and which is continuous with the current suppression first period,
• the maximum reverse feeding period is longer than the current suppression preliminary period, and
• the current suppression first period continues at least until the wire feeding rate becomes 0 during the first transition period.