ESAB AB

An arc electric welding head comprising a first contact device housing a first duct for feeding a first electrode and providing electrical contact between a first power source and said first electrode, a second contact device housing a second duct for feeding a second electrode and providing electrical contact between a second power source and said second electrode, said first and second contact devices being electrically insulated from each other, said first and second ducts being parallel.

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 method of operating a welding power supply during a welding process in which an electric arc between a consumable electrode and a work piece is generated while feeding the consumable electrode and moving the arc in relation to the work piece along a welding track, wherein a transition between a DC power output of the welding power supply and an AC power output of the welding power supply, or vice versa, is made without interruption of the welding process.

An arc welding system includes a temperature determination module and a parameter optimization module. The temperature determination module is configured to determine, from among a plurality of possible temperature categories, a temperature category of an electrode during an interruption to an arc welding process on a workpiece based on a comparison of information indicative of a duration of the interruption to one or more timing thresholds. An electric arc between the electrode and the workpiece is extinguished during the interruption. The parameter optimization module is configured to set one or more current parameters of an output current to be applied to the arc welding process when the arc welding process restarts. The current parameters are based on the temperature category of the electrode determined by the temperature determination module.

A method comprising an arc ignition phase (IP), an arc-stabilizing phase (AP) and a stable arc phase (SP). The arc stabilizing phase comprises an initial sub-phase (IS) comprising the step of feeding at least one hot wire ( 4, 12 ) at constant feed speed and a main sub-phase (MS) comprising the steps of feeding said hot wire at constant feed speed and feeding at least one cold wire ( 22 ) at constant feed speed. The stable arc phase comprises the steps of continuously adjusting the feed speed of the hot wire and continuously adjusting the feed speed of the cold wire. The invention also relates to a welding apparatus ( 1 ) for carrying out the method. The welding apparatus comprises a hot wire feeding means ( 150 ), a contact means ( 2 ), a cold wire feeding means ( 35 ) and a control unit ( 31 ). The control unit is adapted to control said hot wire feeding means to feed the hot wire at a constant feed speed during the initial sub-phase, feed the hot wire at a constant feed speed during the main sub-phase and to continuously during the stable arc phase adjust the feed speed of the hot wire. The control unit is adapted to control said cold wire feeding means to feed the cold wire at a constant feed speed during the main sub-phase and continuously during the stable arc phase adjust the cold wire feed speed.

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.