DC arc welding is performed by alternating a short-circuit period and an arc period. The arc period includes first to fourth periods. A welding current is raised to a first current value in the first period, lowered to a second current value with a time slope in the second period, kept at the second current value in the third period, and raised to a third current value then kept at the value in the fourth period. A wire feeding speed is constant throughout the short-circuit period and the arc period. In the second period, a welding output is under constant voltage control. In the third period and the fourth period, the welding output is under constant current control of the welding output.

A welding system includes a welding power supply, wire feeder, and welding circuit connecting the power supply to the wire feeder. The power supply and the wire feeder are configured for bidirectional communication over the welding circuit. The power supply includes a voltage sensor that measures a voltage level, and a current sensor that measures a current level, on the welding circuit. The power supply is configured to operate in a first welding mode to output a power voltage level to the welding circuit to power the wire feeder in response to a communication from the wire feeder over the welding circuit. The power supply generates periodic voltage dip pulses on the welding circuit, and automatically switches to a second welding mode different from the first welding mode based on the voltage level on the welding circuit falling below a threshold voltage level during a voltage dip pulse.

A welding apparatus for welding workpieces by means of a welding arc which is ignited between a non-consumable welding electrode and the workpieces and produces a molten pool, wherein the welding is performed in a welding process including a plurality of welding cycles, the parameters of which can be set via an interface of the welding apparatus. Each welding cycle of the welding process has a high-current welding phase, during which a high welding current flows, and a low-current welding phase, during which a low welding current flows. In the high-current welding phase and/or in the low-current welding phase of, with the relevant welding cycle being set accordingly, current pulses can be applied, and at the beginning of the high-current welding phase, with the relevant welding cycle being set accordingly, high-frequency ignition pulses can be applied for the contactless ignition of the welding arc.

Systems and methods to control pulse welding are disclosed. An example welding-type system includes: power conversion circuitry configured to convert input power to welding-type power; and control circuitry configured to control the power conversion circuitry to output the welding-type power in a plurality of pulse cycles, each pulse cycle including background, ramp up, peak, and ramp down phases. Controlling the power conversion circuitry involves: during the background phase, controlling the power conversion circuitry in a voltage-controlled mode using a background voltage as a target voltage; during the ramp up phase, controlling the power conversion circuitry by changing the target voltage to a peak voltage; during the peak phase, controlling the power conversion circuitry using the peak voltage as the target voltage; and during the ramp down phase, controlling the power conversion circuitry by changing the target voltage to the background voltage.

An arc welding method includes the following steps. Pulse arc welding is performed with the welding wire being fed in a forward direction during a first period. Short-circuit transfer arc welding is performed with the welding wire being fed in the forward direction and the reverse direction during a second period. The first period and the second period are alternately switched. The switching of the first period to the second period is performed in a manner such that no transfer of a molten droplet of the welding wire occurs during the final pulse cycle of the first period.

A pulsed welding regime includes a peak phase in which energy is added to an electrode and a weld puddle, and a molten ball begins to detach from the electrode, followed by a dabbing phase in which current is significantly reduced to place the ball in the weld puddle with addition of little or no energy. The resulting short circuit clears and the system proceeds to a background phase. The current in the dabbing phase is lower than the current during the background phase. The process may be specifically adapted for particular welding wires, and may be particularly well suited for use with cored wires. The dabbing phase allows for lower energy to be transferred to the sheath of such wires, and resets the arc length after each pulse cycle.

An example welding apparatus includes a welding power source configured to output current between a consumable electrode and a workpiece; a feeding apparatus configured to move the consumable electrode toward the workpiece; and circuitry. The circuitry is configured to: control the welding power source to repeat a sequence including: outputting a positive peak current from the workpiece to the consumable electrode during a positive peak period; outputting a first base current between the consumable electrode and the workpiece during a first base period following the positive peak period, an absolute value of the first base current being less than the positive peak current; and outputting a negative peak current from the consumable electrode to the workpiece during a negative peak period following the first base period, an absolute value of the negative peak current being greater than the absolute value of the first base current. The circuitry is further configured to control the feeding apparatus to move the consumable electrode close to the workpiece so as to temporarily short circuit the consumable electrode and the workpiece during the first base period.

The invention relates to a method for contactless ignition an arc (L) between an electrode (3) and a workpiece (4) which is to be welded, for carrying out a welding process, wherein a welding current (I) and a welding voltage (U) are provided at an output (2) of a welding current source (1), wherein the welding current source (1) contains a resonance converter (5) for generating a periodically varying, preferably substantially sawtooth-shaped, open circuit welding voltage (U.sub.LL) with voltage maxima (U.sub.LL,max) which recur periodically with a repetition rate (f.sub.w) and a welding current source (1) for carrying out the igniting process. In order to achieve reliable contactless ignition of the arc (L) without complicated circuitry, the resonance converter (5) is formed by a series-parallel resonant converter, and temporally synchronous high-frequency pulses (U.sub.I,HF) are superimposed on the open circuit welding voltage (U.sub.LL) in the region of at least some of the periodically recurring voltage maxima (U.sub.LL,max) of the open circuit welding voltage (U.sub.LL).

A multiple welding method and a welding device with at least two electrodes which ensure a welding quality that is as consistent as possible and stable welding processes. A test parameter is applied to one of the at least two welding current circuits before the start or after the end of the multiple welding method and at least one electrical. welding parameter is recorded in at least one other welding current circuit, with an electrically conductive connection between the at least two welding current circuits being detected if the recorded welding parameter is influenced by the test parameter and fulfills a predetermined test criterion. Alternatively, at least one electrical welding parameter is recorded in each welding current circuit during the multiple welding method, with an electrically conductive connection between the at least two welding current circuits being detected if the recorded welding parameters change simultaneously.

A system and method generates a short circuit arc welding waveform output, having a pinch phase with a break point and a necking threshold, between a welding electrode and a work piece during a short circuit arc welding process. A necking threshold energy and a break point energy of the short circuit arc welding waveform output are monitored during the short circuit arc welding process, and a running average of the necking threshold energy is generated. An actual pinch energy relationship value is calculated based on the running average of the necking threshold energy and the break point energy, and is compared to a previously specified pinch energy relationship value. The break point energy of the short circuit arc welding waveform output is adjusted in response to the comparison to maintain the actual pinch energy relationship value to be at the specified pinch energy relationship value.