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.

The invention relates to a method and a device (1) for welding by means of a non-consumable electrode (2), wherein a welding current (I) alternating in polarity at a welding frequency (f.sub.S) is applied by a current source (3) between the electrode (2) and a workpiece (4) in order to form an arc (5), and the polarity is changed back to the polarity before the polarity change if the voltage (U) is above the voltage threshold value (U.sub.S+, U.sub.S−) and the welding current (I) is below the current threshold value (I.sub.S+, I.sub.S−). According to the invention, the welding voltage (U) and the welding current (I) after a preset duration (Δt) after the polarity change are compared with the voltage threshold value (U.sub.S+, U.sub.S−) and the current threshold value (I.sub.S+, I.sub.S−), and in addition the power (P) in the arc (5) is determined, and the polarity is changed back if the welding voltage (U) is greater than the voltage threshold value (U.sub.S+, U.sub.S−), and/or if the welding current (I) is less than the current threshold value (I.sub.S+, I.sub.S−), and/or the determined power (P) is less than a preset power threshold value (P.sub.S).

My invention is an improvement to a welding arc igniter. My invention periodically disables the arc igniter for one or more AC half-cycles. When the igniter skips an AC half-cycle, the welding arc may not ignite, so average weld heat is reduced. AC weld heat can be adjusted in real time, by varying the fraction of AC half-cycles that are skipped. AC polarity balance can be adjusted in real time, by preferentially skipping the electrode-positive or electrode-negative half-cycles.

Method and device for igniting and/or re-igniting a welding arc (SLB) between a wire end of a consumable welding wire electrode (SDE) and a workpiece (W), comprising the steps of: determining (S1) a distance (S) or time duration required by the wire end of the consumable welding wire electrode, SDE, until contact or short-circuit with a surface of the workpiece (W); and igniting (S2) the welding arc (SLB) with an ignition energy, E.sub.Z, which is set in dependence upon the determined distance (S) or time duration.

An arc welding method alternately generates a short-circuit state and an arc state. In the method, short circuits are generated also in the arc period. This more than doubles the total number of short circuits, which is the sum of the short circuits generated in the short circuit period and those generated in the arc period. This enables a thin plate to be arc welded at a higher speed, while reducing its burn-through.

The invention relates to a method and a device (1) for welding by means of a non-consumable electrode (2), wherein a welding current (I) alternating in polarity at a welding frequency (f.sub.s) is applied by a current source (3) between the electrode (2) and a workpiece (4) in order to form an arc (5), and the polarity is changed back to the polarity before the polarity change if the voltage (U) is above the voltage threshold value (U.sub.s+, U.sub.s−) and the welding current (I) is below the current threshold value (I.sub.s+, I.sub.s−). According to the invention, the welding voltage (U) and the welding current (I) after a preset duration (Δt) after the polarity change are compared with the voltage threshold value (U.sub.s+, U.sub.s−) and the current threshold value (I.sub.s+, I.sub.s−), and in addition the power (P) in the arc (5) is determined, and the polarity is changed back if the welding voltage (U) is greater than the voltage threshold value (U.sub.s+, U.sub.s−), and/or if the welding current (I) is less than the current threshold value (I.sub.s+, I.sub.s−), and/or the determined power (P) is less than a preset power threshold value (P.sub.s).

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.

An example welding-type power supply, 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 based on a voltage-controlled control loop; and in response to detecting an output voltage less than a threshold voltage: during a first state, control the voltage-controlled control loop based on a first value of a control parameter of the voltage-controlled control loop to increase a response rate of the voltage-controlled control loop; and during a second state following the first state, control the voltage-controlled control loop based on a second value of the control parameter, wherein the second value of the control parameter causes a reduction in energy output by the power conversion circuitry relative to the first state.

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 that repeats short-circuit and arcing, 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. This reduces the heat input amount into a welding object and suppresses burn through and a strain upon welding while making the arc stable.

My invention is an improvement to a welding arc igniter. My invention periodically disables the arc igniter for one or more AC half-cycles.

When the igniter skips an AC half-cycle, the welding arc may not ignite, so average weld heat is reduced.

AC weld heat can be adjusted in real time, by varying the fraction of AC half-cycles that are skipped.

AC polarity balance can be adjusted in real time, by preferentially skipping the electrode-positive or electrode-negative half-cycles.