A method of controlling arc welding with a consumable electrode includes repeating the following periods in sequence: a short-circuit welding period to perform short-circuit arc welding; a pulse welding period to perform pulse welding; and a cooling period in which the welding current output is zero.

Disclosed is an arc welding control method of controlling a welding current in short-circuit arc welding of feeding a welding wire toward a base metal and alternating a short-circuit state and an arc state. The arc welding control method includes: executing, in the short-circuit state, a first increase in the welding current with a first slope, a first decrease in the welding current to a first bottom value after executing the first increase, a second increase in the welding current with a second slope after executing the first decrease, and a second decrease in the welding current to a second bottom value that is smaller than the first bottom value after executing the second increase to shift a state to the arc state.

An apparatus to provide welding power. The apparatus may include a direct current-alternate current (DC-AC) power converter to output a primary current and a transformer stage. The transformer stage may include at least one power transformer to receive the primary current from the (DC-AC) power converter on a primary side of the transformer stage and to output a first voltage through a first rectifier and a first set of secondary windings disposed on a secondary side of the transformer stage. The transformer stage may further include an auxiliary set of secondary windings disposed on the secondary side to output a second voltage. The apparatus may also include a pair of active unidirectional switches disposed on the secondary side to receive the second voltage from the auxiliary set of secondary windings.

A welding system is provided which utilizes a short arc welding method in which the waveforms have a positive polarity portion and negative portion to optimize heat input and provide heat and current control.

A pulse welding period alternately includes a first peak period in which a first peak current whose peak value is a first current value is caused to flow through a welding wire and a base period in which a base current having a second current value is caused to flow through the welding wire. During the base period, a second peak current whose peak current value is a sum of a second current value and a third current value and is smaller than the first current value is superimposed on the base current at a second pulse frequency. A second peak period in which the second peak current is caused to flow once is shorter than the first peak period. During the first peak period, a droplet is transferred from the welding wire toward a base material.

The invention relates to an arc welding method using a consumable welding wire (1), wherein in successive welding cycles (SZ) during a welding process (P.sub.i) a certain welding current (I(t)) is applied to the welding wire (1) and the welding wire is moved with a certain wire conveying speed (v(t)) towards a workpiece (2) to be processed. The aim of the invention is to further improve the stability of the welding method. The aim is achieved, according to the invention, in that in the event of a change of the welding process (P.sub.1) to a welding process (P.sub.2) with an increased mean wire conveying speed (v.sub.mean) during a welding cycle (SZ) and/or with an increased mean welding current (I.sub.mean) during a welding cycle (SZ), a lowering phase (AP) is initiated, wherein in the lowering phase (AP) the welding current (I.sub.A(t)) is lowered for a specified duration (Δt.sub.A).

An arc welding method preforms reciprocating wire feed so as to alternately perform forward feed and reverse feed. The arc welding method includes a normal arc welding step, a normal short circuit welding step, and an abnormal arc welding step. In the abnormal arc welding step, a short circuit state occurs at a second time point, which is before a lapse of a second period from a first time point at which an arc state occurs. Further, in the abnormal arc welding step, the reciprocating wire feed continues until a third time point after a lapse of a first period from the second time point. At the third time point, the reciprocating wire feed is stopped and the abnormal arc welding step is completed. From the third time point, the welding wire is decelerated and the reciprocating wire feed is restarted.

An arc welding control method, using shield gas containing 60 volume percent or more of inert gas, is configured to: alternately switch the wire feeding speed between forward and backward feeding; repeat a short-circuiting period and an arc period; and switch a first, second and third arc period over time during the arc period, where a first arc current Ia1 is fed for the first arc period, a second arc current Ia2 is fed for the second arc period, and a third arc current Ia3 is fed for the third arc period such that Ia1>Ia2>Ia3 holds. The first arc current Ia1 is set to a critical current value or more. The first arc period is so short that a droplet transfer does not occur. The second arc current Ia2 is less than the critical current value.

Specific AC welding waveforms are utilized to increase the toughness level of austenitic stainless steel above what is achieved using the same welding consumables using standard DC welding waveforms.

In thin sheet welding, when a heat input amount relative to a sheet thickness is too large, a welding defect such as a deviation from aim due to occurrence of a strain or burn through may easily occur. When a welding current is decreased to reduce the heat input amount, there is an issue in which an arc tends to become unstable. In arc welding in which short-circuit and arcing are repeated, first heat input period (Th) and second heat input period (Tc) having a heat input amount less than that of first heat input period (Th) are periodically repeated and a welding current during an arc period in second heat input period (Tc) is decreased to extinguish the arc. This reduces the heat input amount into a welding object and suppresses burn through or a strain upon welding, while making the arc stable.