Esab Ab

Tomas Johansson

Hannes Hugo Raudsepp

Martin Andersson

Rikard Ljungkvist

Bo Melin

Ulf Nicklas Andrén

Daniel Lennartsson

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 () 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 () 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 () for carrying out the method. The welding apparatus comprises a hot wire feeding means (), a contact means (), a cold wire feeding means () and a control unit (). 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.

Method for starting a submerged arc welding process and welding apparatus

A submerged arc welding apparatus includes a first wire feeder feeding a first hot wire towards a work piece; a first contact tube transferring current to the first hot wire for arc generation to create a weld puddle; a second wire feeder feeding a cold wire at a variable feed speed towards the weld puddle; one or more sensors configured to continuously measure, during a welding phase, at least a first active welding parameter related to at least the first hot wire; and a control unit. The control unit is configured to determine different target values for the variable feed speed of the cold wire based on different values of the at least a first active welding parameter such that a different target value for the variable feed speed of the cold wire is determined according to a different value of the at least a first active welding parameter.

Method and system for submerged arc welding

The invention relates to a method for submerged arc welding comprising the steps of guiding a first hot wire () towards a work piece and guiding a cold wire () at a variable feed speed. The method further comprises the steps of continuously measuring, during a welding phase, at least a first active welding parameter related to at least said first hot wire () adjusting the cold wire () feed speed in dependence on at least first active welding parameter variations, to maintain high welding stability and high weld quality. The invention also relates to a system () for carrying out the method. The system () comprises hot wire feeding means () for feeding a first hot wire () towards a work piece and cold wire feeding means () for feeding a cold wire () at a variable cold wire () feed speed and a control unit () for controlling the second wire feeding means (). The system () also comprises measuring means () adapted to continuously measure at least a first active welding parameter related to said first hot wire (). The control unit () determines target values for the cold wire () feed speed, each target value corresponding to a first active welding parameter value and controls said second wire feeding means () to adjust said cold wire () feed speed to said target values.

An electric arc welding method is provided, wherein an electrode assembly comprises at least two fusible continuous electrodes acting on a workpiece for generating a weld pool via electric arcs, wherein the at least two electrodes are arranged in sequential order relative to a welding direction and laterally separated relative to each other, wherein steps are performed of monitoring at least one stability parameter (Stab_par) for each electrode of the electrode assembly; determining if one electrode of the electrode assembly violates a stability criterion (Crit); separating at least temporarily the one electrode violating the stability criterion (Crit) from one or more adjacent electrodes when a violation of the stability criterion (Crit) of the one electrode is detected.

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Laxa, Sweden

Tomas Johansson