Wire-position-controlled short arc method

Abstract

The invention relates to an arc welding method using a consumable wire electrode (152), having a plurality of welding cycles (SZ), each of which has a short-circuit phase (KSP) and an arc phase (LBP), in which the wire electrode (152) is conveyed at a variable conveying speed (vF(t)) and in which the conveying speed (vF(t)) and / or the welding current (I(t)) is / are changed on the basis of a value (x(t)) for the current position of the wire electrode (152), in particular if the value (x(t)) for the current position of the wire electrode (152) has reached, fallen short of, or overshot a specified position (xC, xD). The invention further relates to a controller (114) for a welding device (100) and to a welding device (100) having such a controller (114).

Description

[0001]August 28, 2025 Wire Position-Controlled Short-Arc Welding Process The present invention relates to a method for arc welding with a consumable wire electrode (welding wire) comprising a plurality of welding cycles, each having a short-circuit phase and an arc phase. The present invention further relates to a control device for a welding apparatus and to a welding apparatus with such a control device. Arc welding processes with welding cycles, each having a short-circuit phase and an arc phase, are generally known as so-called short-arc welding processes. EP 1563938 B1, for example, describes a short-arc welding process in which a counter-voltage is applied towards the end of the short-circuit phase to prevent spatter during short-circuit resolution.EP 3509784 B2 also describes a short-arc welding process in which a reverse terminal velocity of the wire electrode is reached before the short circuit is cleared. Many known processes have in common that the speed of the wire electrode is adjusted depending on the short-circuit signal of the welding device. Due to uneven short-circuit durations, this results in varying heat inputs, which also prevent a high degree of uniformity in the welding process. Against this background, the present invention aims to provide a short-arc welding process, a control device for a welding device, and a welding device that enables an improved welding process, in particular reducing or avoiding disadvantages of the prior art.The aforementioned problem is solved according to the invention by a method for arc welding with a consumable wire electrode comprising a plurality of welding cycles, each having a short-circuit phase and an arc phase, in which the wire electrode is fed at a variable feed rate and in which the feed rate and / or the welding current is changed depending on a value for the current position of the wire electrode, in particular when the value for the current position of the wire electrode reaches a predetermined position, especially when it exceeds or falls below a predetermined position. In this way, the welding process can be controlled, for example, depending on the distance of the wire electrode to the weld pool. This particularly enables control of the welding process with specified distances.In this way, various welding parameters, especially the acceleration of the wire electrode or current shaping, can be controlled depending on the position of the wire electrode relative to the weld pool. This allows, for example, a high degree of uniformity in the welding process, targeted control of heat input during the short-circuit and / or arc phases, and / or, depending on the application, minimal immersion depths of the wire electrode into the weld pool and / or consistent arc lengths. Furthermore, by controlling the position of the droplets on the wire electrode, it is possible to shape them in such a way as to promote short-circuit transition or to enable adapted heat input at high deposition rates. Such a welding process controlled by the wire electrode position is particularly advantageous compared to a welding process controlled solely by the wire electrode speed.The process is for arc welding with a consumable wire electrode. The process is preferably carried out under a shielding gas. Accordingly, SE / sw 240837WO, dated August 28, 2025, states that the process is preferably a metal inert gas welding process (MIG welding process), for example, a metal inert gas welding process (MIG welding process) or a metal active gas welding process (MAG welding process). The process comprises a plurality of welding cycles, each with a short-circuit phase and an arc phase. Preferably, the welding cycles of the plurality of welding cycles follow one another. The sequence of welding cycles of the plurality of welding cycles can be interrupted by one or more other intermediate welding cycles, for example, pulse process welding cycles.A hybrid welding process is also conceivable, in which sequences of one or more welding cycles, each with a short-circuit phase and an arc phase, alternate with sequences of one or more intermediate welding cycles without a short-circuit phase. The welding cycles each have a short-circuit phase and an arc phase. The short-circuit phase begins, in particular, when a short circuit occurs between the wire electrode and the weld pool and lasts until the subsequent short circuit is cleared. The arc phase begins, in particular, when the short circuit is cleared and lasts until the subsequent short circuit occurs. During the arc phase, a welding arc burns, in particular, between the wire electrode and a workpiece. The arc phase preferably includes an arc withdrawal phase in which the wire electrode is moved (withdrawn) away from the weld pool.The arc phase preferably comprises an arc approach phase in which the wire electrode is conveyed towards the molten pool. Preferably, the arc approach phase of an arc phase follows the arc removal phase of the arc phase SE / sw 240837WO August 28, 2025. The short-circuit phase preferably comprises a short-circuit approach phase in which the wire electrode is conveyed towards the molten pool. The short-circuit phase preferably comprises a short-circuit removal phase in which the wire electrode is conveyed away from the molten pool. Preferably, the short-circuit removal phase of a short-circuit phase follows the short-circuit approach phase of the short-circuit phase. In the process, the wire electrode is conveyed at a variable conveying speed. The conveying speed vF is therefore preferably a function of time, vF(t).The feed rate corresponds – except for negligible differences due to slippage – to the wire speed of the wire electrode. In this process, the feed rate and / or the welding current are changed depending on a value for the current position of the wire electrode. In particular, the feed rate can be changed depending on a value for the current position of the wire electrode. In this way, the feed rate can be adjusted, for example, depending on the distance of the wire electrode to the weld pool, to ensure reliable droplet transfer, to prevent the wire electrode from being immersed too deeply in the weld pool, or to increase the welding speed. Additionally or alternatively, the welding current can be changed depending on a value for the current position of the wire electrode.In this way, for example, the welding current can be synchronized with the wire movement, for instance to achieve a more uniform weld. The feed rate and / or the welding current can be changed, in particular, when the value for the current position of the wire electrode reaches a predetermined position, especially when it exceeds or falls below a predetermined distance between the wire electrode and the weld pool, for example, SE / sw 240837WO 28 August 2025. The value for the current position of the wire electrode is preferably a calculated value. In particular, the value for the current position of the wire electrode can be determined depending on a reference position of the wire electrode and the feed rate or a feed path.The reference position specifies and / or defines the position of the wire electrode at a particular reference point, for example, to a predetermined reference value such as zero. The reference position, particularly at the reference point, preferably relates to the actual position of the wire electrode, preferably in terms of the distance of the wire electrode to the weld pool surface. The value for the current position can then be calculated, for example, from the reference position by integrating the time-dependent feed rate from the reference point to the current point in time. For integrating the feed rate, target values ​​can be used, or, to increase accuracy, measured feed rate values ​​can be used, for example, by means of a rotary velocity sensor provided on a wire electrode feeder for conveying the wire electrode.Furthermore, the value for the current position can be calculated from the reference position by adding a conveying distance. To determine the conveying distance traveled since the reference time, signals from a stepper motor of the wire electrode feeder can be used, or, to increase accuracy, values ​​for the distance can be recorded, for example, by a displacement sensor provided on the wire electrode feeder, such as a rotary angle sensor (SE / sw 240837WO August 28, 2025). If, for example, the stepper motor or rotary angle sensor delivers a pulse after sweeping a specific angle Δγ, then x(t) can be determined incrementally by adding or subtracting a corresponding differential displacement (e.g., rRolle · Δγ, where rRolle is the radius of the corresponding wire feeder roller of the wire feeder) for each pulse.When determining the value for the current position, the melting of the wire electrode can optionally be taken into account, for example, by integrating a melting rate, defined by a characteristic curve, from the reference time to the current time. However, the melting of the wire electrode can also be omitted, for example, by appropriately selecting the predefined position and regularly choosing a new reference position, such as at the beginning of each welding cycle. The reference position can be determined, in particular, based on the position of the wire electrode at the onset and / or resolution of the short circuit in the current and / or a previous welding cycle. Specifically, the position of the wire electrode at the onset (or resolution) of the short circuit can be used as the reference position.For example, a predetermined value, such as zero, can be set for the position of the wire electrode at the time of short-circuit occurrence (or at the time of short-circuit resolution). The time of short-circuit occurrence (or short-circuit resolution) can then be used as a reference time for calculating the value for the current position of the wire electrode. According to the invention, the above-mentioned problem is further solved by a control device for a welding apparatus with at least one microprocessor and at least one memory containing instructions, the execution of which on the at least one microprocessor causes an arc welding process to be carried out according to the method described above or an embodiment thereof.The aforementioned problem is further solved according to the invention by a welding device comprising the control device described above or an embodiment thereof. The welding device particularly includes a welding power source, wherein the control device may preferably be a control device of the welding power source. The welding device further preferably includes a welding torch. The welding device particularly includes a wire feeder for feeding a wire electrode. The wire feeder is preferably arranged on or integrated into the welding torch. In this way, highly dynamic wire feeding with variable feed speed is enabled, so that the feed speed of the wire electrode can be reliably controlled in a time-dependent manner within the individual welding cycles.The welding device may further include a wire feeder with an additional wire feeder upstream of the wire feeder. This additional wire feeder may, for example, be configured and / or controlled by the control unit such that the wire electrode is fed at one or more average feed speeds. Adjustment of the feed speed within a welding cycle can then be achieved by the wire feeder downstream of the additional wire feeder. To compensate for differences between the feed speeds of the additional wire feeder and the main wire feeder, a wire accumulator (SE / sw 240837WO 28 August 2025) may be provided between the additional wire feeder and the main wire feeder.The wire storage unit can, in particular, comprise one or more movable rollers around which the wire electrode is guided, so that mechanical stresses in the wire electrode caused by differences in conveying speeds can be compensated by moving the rollers. It is also conceivable to omit the wire storage unit, especially when using a wire guide that has a sufficiently large inner cross-section compared to the outer cross-section of the wire electrode guided therein, preferably a wire guide whose inner diameter is at least 5 mm larger than the diameter of the wire electrode. The wire conveying device and / or the further wire conveying device can, in particular, have one or more opposing rollers between which the wire electrode is guided, wherein at least one, and preferably at least two, opposing rollers are driven.To accurately measure the feed rate and / or the feed path, the welding device preferably includes a feed rate measuring device and / or a feed path measuring device, particularly on the wire feeder. The feed rate measuring device can, for example, include a rotary speed sensor on a roller of the wire feeder. The feed path measuring device can, for example, include a rotary angle sensor on a roller of the wire feeder. A rotary encoder can be provided as the rotary speed sensor and / or rotary angle sensor. The wire feeder and the feed rate and / or feed path measuring device are connected to the control unit, for example, via a wired or wireless communication link. SE / sw 240837WO 28.August 2025 The following describes various embodiments of the method, the control device, and the welding apparatus, with each embodiment applying independently to the method, the control device, and the welding apparatus, respectively. Furthermore, the individual embodiments can be combined with one another as desired. In one embodiment, the arc phase includes an arc approach phase in which the wire electrode is fed towards a weld pool. During this approach phase, the feed rate and / or the welding current are changed depending on a value representing the current position of the wire electrode. In this way, the short circuit can be prepared based on the electrode's position.Preferably, the feed rate and / or the welding current are changed when the value for the current position of the wire electrode reaches, in particular falls below, or exceeds a predetermined distance value. The predetermined distance value is, in particular, a predetermined distance to the reference position, which, for example, can correspond to the position of the weld pool surface at the reference time. Specifically, the feed rate can be reduced to a lower absolute value after reaching the predetermined distance value. This prevents the wire electrode from being immersed too deeply in the weld pool during the subsequent short-circuit phase. Furthermore, this method can achieve favorable droplet formation and detachment. Alternatively, the feed rate can be increased to a higher absolute value after reaching the predetermined distance value.In this way, the welding current can be increased without causing premature droplet detachment from the wire electrode. Furthermore, a short circuit can be mechanically induced in this manner. In addition to or as an alternative to changing the feed rate, the welding current can also be changed depending on the current position of the wire electrode, particularly when the predefined distance is reached or fallen below. For example, an increase in current can be synchronized with a distance-dependent acceleration of the wire electrode to increase the welding energy without premature droplet detachment. Conversely, a decrease in current can be induced when the wire electrode reaches a predefined position to trigger droplet detachment.In one embodiment, the short-circuit phase includes a short-circuit removal phase in which the wire electrode is moved away from the weld pool. During this removal phase, the wire electrode's conveying speed is increased, preferably at a decreasing rate. This increase in conveying speed during the removal phase allows the wire electrode to be pulled out of the weld pool more quickly, thus enabling the short-circuit phase to be completed sooner and the welding process to be faster, particularly at a higher frequency. The preferably decreasing rate of increase in conveying speed, i.e., the decreasing acceleration of the wire electrode, prevents excessive speed during short-circuit resolution and thereby reduces the deceleration of the wire electrode.In one embodiment, the feed rate of the wire electrode is increased during the short-circuit removal phase until a predetermined time has elapsed since the short circuit occurred, or, if the short circuit is resolved before the predetermined time has elapsed, until the short circuit is resolved (SE / sw 240837WO, August 28, 2025). If the predetermined time elapses before the short circuit is resolved, the feed rate can then remain constant, decrease, or increase until the short circuit is resolved. Alternatively, the feed rate of the wire electrode can be increased during the short-circuit removal phase until a predetermined distance has been covered since the short circuit occurred, or, if the short circuit is resolved before the predetermined distance has been covered, until the short circuit is resolved.Once the wire electrode has traversed the predetermined distance before short-circuit resolution, the conveying speed can subsequently remain constant, decrease, or increase until the short circuit is resolved. This ensures that the wire electrode is accelerated over a sufficiently long period or distance to resolve the short circuit more quickly. In one embodiment, the arc phase includes an arc removal phase in which the wire electrode is conveyed away from the molten pool. During this phase, the conveying speed of the wire electrode is reduced until the direction reverses. This allows the wire electrode to be retracted further after the short circuit is resolved, reaching a top dead center at the point where the direction reverses, thus establishing a stable arc.The feed rate of the wire electrode is preferably reduced during the arc removal phase only from a point in time dependent on the value of the current position of the wire electrode, for example, when the value of the current position of the wire electrode reaches, and in particular exceeds, a predetermined position value. If the value of the current position of the wire electrode reaches or exceeds the predetermined position value at the beginning of the arc removal phase, the feed rate of the wire electrode is preferably reduced in magnitude from the beginning of the arc removal phase. SE / sw 240837WO August 28, 2025. In this way, the top dead center when the direction of the wire electrode is reversed can be precisely set, in particular at a constant distance from the weld pool, thus resulting in a more uniform welding process.In one embodiment, the rate at which the feed rate of the wire electrode is reduced during the arc removal phase until the direction reversal is set such that the direction reversal is reached after a predetermined time since the short circuit was cleared. This allows the top dead center of the wire electrode to be reached at a desired time, thus enabling a more uniform welding process. In another embodiment, the feed rate of the wire electrode is maintained at or below a predetermined speed value for a predetermined time during the direction reversal. The predetermined speed value can, in particular, be zero; that is, the wire electrode is preferably held at the top dead center for a predetermined time during the direction reversal. This allows the weld pool to settle.In one embodiment, the method comprises multiple pulsed welding cycles without a short-circuit phase. Accordingly, the method can be a hybrid process in which, within a single welding operation, a change occurs between a short-arc process (i.e., a welding process with a short-circuit phase) and another welding process, particularly a pulsed process. Preferably, one or more parameters of a subsequent welding cycle without a short-circuit phase (in particular, a pulsed welding cycle) are set based on the current position of the wire electrode. In this way, the value for the current position of the wire electrode, which can be readily determined during the short-arc process (SE / sw 240837WO 28 August 2025), can be used to set the subsequent welding cycle, where the value for the current position would be more difficult to determine due to the absence of a short-circuit phase.In particular, one or more welding cycles following a welding cycle with a short-circuit phase can be operated without a short-circuit phase using transition values ​​for one or more parameters that differ from the values ​​for the one or more parameters of the subsequent welding cycles without a short-circuit phase. The number of welding cycles operated with the transition values ​​depends on the current position of the wire electrode. For example, the welding cycles following a welding cycle with a short-circuit phase can be operated with the transition values ​​until the wire electrode has been advanced by the stickout point during the welding cycle with a short-circuit phase.In this way, the heating of this stickout by the short-circuit current during the short-circuit phase can be taken into account in the subsequent initial welding cycles without a short-circuit phase, until a wire segment not subjected to the short-circuit current has advanced. In one embodiment, a counter-voltage is applied in series with the welding voltage during the short-circuit phase, particularly when a predefined condition for the welding voltage value is reached. This allows the short-circuit resolution to be accelerated and weld spatter to be reduced. The predefined condition could, for example, be the exceeding of a predetermined welding voltage threshold or a predetermined welding voltage change. Further features and advantages of the method, the control device, and the welding apparatus will become apparent from the following description of exemplary embodiments, with reference to the accompanying drawing.SE / sw 240837WO August 28, 2025 In the drawing, Fig. 1 shows an embodiment of the control unit and the welding device, Fig. 2 an example of a wire storage unit, Fig. 3 several diagrams over a common time axis to illustrate an embodiment of the method, Fig. 4 further diagrams over a common time axis for the embodiment of the method from Fig. 3, and Fig. 5 further diagrams over a common time axis for the embodiment of the method from Fig. 3. Fig. 1 shows an embodiment of the control unit and the welding device in a schematic view. The welding device 100 is designed for metal inert gas (MIG) welding, for example, for metal inert gas (MIG) or metal active gas (MAG) welding. The welding device 100 comprises a welding power source 110 for providing a welding current with a power unit 112 and a control unit 114.The control unit 114 comprises a microprocessor 115 and a memory 116 containing instructions. The control unit 114 is configured to control the welding power source 110 and, in particular, controls the power unit 112. For this purpose, the memory 116 contains, in particular, corresponding instructions, the execution of which on the microprocessor 115 controls the welding power source. The power unit 112 is configured to provide a welding current for welding via an electrical output 118 of the welding power source 110. The welding device 100 further comprises a wire feeder 150 for transporting a wire electrode 152.The wire feeder 150 comprises a wire electrode supply 154 in the form of a wire electrode drum, a primary wire electrode feeding device 156, which preferably includes driven rollers for the controlled feeding of the wire electrode 152, and a control device 160 designed for controlling the wire feeder 150. The wire feeder 150 further comprises an electrical input 162 for supplying the welding current provided by the welding power source 110, which is connected to the electrical output 118 of the welding power source via an electrical line 119 for operation. The wire feeder 150 also comprises a shielding gas inlet 164 for supplying a shielding gas, which is connected to a shielding gas source 166, such as a gas cylinder, via a gas line 165 for operation.The wire feeder 150 further comprises a torch connection 168 for connecting a welding torch 180 of the welding device 100. The wire electrode 152 fed by the primary wire electrode feeder 156, the welding current supplied by the welding power source 110, and the shielding gas supplied by the shielding gas source 166 are supplied to the welding torch 180 via the torch connection 168. The control unit 160 is specifically designed to control the primary wire electrode feeder 156. Furthermore, the control unit 160 can be configured to control the shielding gas flow supplied at the torch connection 168. For this purpose, the wire feeder 150 can have, for example, a controllable valve 169 between the shielding gas inlet 164 and the torch connection 168, with which the shielding gas flow can be adjusted.The control unit 114 of the welding power source 110 and the control unit 160 of the wire feeder 150 are preferably connected to each other via a communication link, for example via line 119 or via a separate data line, so that one of the two control units 114, 160 can transmit control commands to the other of the two control units 114, 160. In this way, for example, the control unit 114 can be configured to control both the welding power source 110 and the wire feeder 150. A user interface 122, 172 is preferably provided on the welding power source 110 and / or on the wire feeder 150, via which the user can read operating information and / or enter control commands. The welding torch 180 comprises a torch section 182 and a hose assembly 184.The hose assembly 184 is connected to the torch connection 168 of the wire feeder 150, so that during operation the wire electrode 152 fed by the primary wire electrode feeder 156 is guided via the torch connection 168 through a wire guide 185 running through the hose assembly 184 in the form of a hollow line to the torch part 182, and the welding current supplied by the welding power source 110 and looped through the wire feeder 150 is further guided via the torch connection 168 through an electrical line running through the hose assembly 184 to the torch part 182, where the welding current is directed to the wire electrode 152 via a contact. A secondary wire electrode feeder 186 is arranged in the torch part 182, which preferably includes driven rollers for the controlled feeding of the wire electrode 152 and allows for precise and dynamic adjustment of the SE / sw 240837WO 28.August 2025. The feed rate at which the wire electrode 152 exits the torch part 182 is permitted. The secondary wire electrode feeder 186 is also controlled by the control unit 114, for example, via a data line integrated into the hose assembly 184. During operation, the wire electrode 152 is fed by the primary wire electrode feeder 156 at a variable primary feed rate vP(t) and by the secondary wire electrode feeder 186 at a variable secondary feed rate vF(t). The primary feed rate can, in particular, be an average feed rate. The actual exit velocity of the wire electrode 152 from the torch part 182, which can change several times or continuously within a welding cycle, corresponds to the secondary feed rate. The feed rate vF(t) can be positive or negative.A positive feed rate vF(t), i.e., vF(t) > 0 m / min, means that the wire electrode 152 is moved out of the torch part 182, i.e., when welding a workpiece 200, it is moved towards the weld pool 202 (arrow 204). A negative feed rate vF(t), i.e., vF(t) < 0 m / min, means that the wire electrode 152 is moved into the torch part 182, i.e., when welding a workpiece 200, it is moved away from the weld pool 202 (arrow 206). The feed of the wire electrode 152 by the wire electrode feeder 156 results in a feed path sF(t). With a positive conveying velocity vF(t), the conveying distance sF(t) increases; with a negative conveying velocity vF(t), the conveying distance sF(t) decreases.To accurately measure the conveying speed vF(t) or the conveying distance sF(t), a conveying speed and / or conveying distance measuring device 187, SE / sw 240837WO August 28, 2025, for example in the form of a rotary encoder on one of the driven rollers, is provided on the secondary wire electrode conveying device 186. Differences between the primary and secondary conveying speeds can be compensated for by an optional wire storage unit 190 connected between the primary and secondary wire electrode conveying devices 156, 186. Fig. 2 shows a schematic representation of such a wire storage unit 190, which has a play of spring-loaded rollers 192 around which the wire electrode 152 is guided.Alternatively, a wire guide 185 with a larger inner diameter than the outer diameter of the wire electrode 152 can provide sufficient clearance for the wire electrode to compensate for differences in the primary and secondary feed rates. Furthermore, during operation, the shielding gas flow supplied at the torch connection 168 is routed through a shielding gas line running through the hose assembly 184 to the torch part 182 to create a shielding gas atmosphere for the welding process. Finally, a torch trigger 188 is provided on the torch part 182 for initiating a welding process. A method for arc welding with the welding device 100 is described below with reference to Fig. 3. The method is controlled by the control unit 114 of the welding power source 110, for example, by actuating the torch trigger 188.Figure 3 shows several diagrams over a common time axis to illustrate an embodiment of the method. SE / sw 240837WO August 28, 2025. Diagram (a) shows the welding current I(t), diagram (b) shows the welding voltage U(t), diagram (c) shows the short-circuit phase (0) or the arc phase (1) as a digital signal, diagram (d) shows the feed rate vF(t) of the wire electrode 152 measured by the feed rate sensing device 187, and diagram (e) shows a value x(t) for the position of the wire electrode, which is determined from a reference position by adding a measured feed distance s(t) or by integrating the feed rate vF(t).For the sake of clarity, the sign for vF(t) is chosen such that positive velocity values ​​correspond to movement towards the melt pool and negative velocity values ​​to movement away from the melt pool. Furthermore, the sign for x(t) is chosen such that when the melt pool surface is at zero, positive values ​​are above the melt pool surface (outside the melt pool) and negative values ​​are below the melt pool surface (inside the melt pool). This choice of sign results in a sign reversal between x(t) and vF(t), i.e., a positive velocity value vF(t) leads to a change in x(t) towards the negative and vice versa. Above the diagrams, a schematic representation of wire electrode 152, workpiece 200, and melt pool 202 at several selected times (t1 to t7) is shown.The welding process comprises a plurality of successive welding cycles SZ, one of which is shown in Fig. 3. Each welding cycle SZ has a short-circuit phase KSP and an arc phase LBP. Furthermore, the short-circuit phase KSP has a short-circuit approach phase KS-AP and a short-circuit distance phase KS-EP. The arc phase LBP accordingly has an arc distance phase LB-EP and an arc approach phase LB-AP. SE / sw 240837WO August 28, 2025. During the short-circuit approach phase KS-AP and the arc approach phase LB-AP, the wire electrode 152 is fed towards the weld pool 202. During the short-circuit distance phase KS-EP and the arc distance phase LB-EP, the wire electrode 152 is fed away from the weld pool 202.The control unit 114 uses appropriate measuring devices to detect the welding current I(t) supplied by the welding power source 110, which flows from the wire electrode 152 to the workpiece 200 during welding, and the welding voltage U(t) supplied by the welding power source 110, which – apart from minor voltage losses due to line resistances – is present between the wire electrode 152 and the workpiece 200. The control unit 114 is configured to detect the onset of a short circuit (t1 in Fig. 3) and the resolution of the short circuit (t3 in Fig. 3) depending on the welding voltage U(t). If the welding voltage U(t) falls below a predetermined threshold value, e.g., 10 V, during the arc phase, the control unit 114 detects the onset of a short circuit. If the welding voltage U(t) rises above a predetermined threshold value, e.g., 15 V, during the short-circuit phase, the control unit 114 detects the resolution of the short circuit.The control unit 114 also continuously receives the feed rate vF(t) of the wire electrode 152 measured by the feed rate and / or feed distance detection unit 187, or the measured feed distance sF(t) of the wire electrode 152, for example via the data line integrated into the hose assembly 184. The control unit 114 is configured to control the secondary wire electrode feed unit 186 to adjust the feed rate vF(t) and the power unit 112 to adjust the welding current I(t), in particular depending on a value x(t) for the current position of the wire electrode. SE / sw 240837WO August 28, 2025. The control unit 114 can determine the value x(t) for the current position of the wire electrode 152 based on the feed rate vF(t) or the feed distance sF(t) and a reference position.The control unit 114 can, for example, use the position of the wire electrode 152 at the time of the short circuit as a reference position. The time of the short circuit is then the reference time. To do this, the control unit 114 can set the value x(t1) for the position of the wire electrode 152 at the time of the short circuit (at t1) to a predefined value, for example x(t1) = 0 mm, and store the time t1 of the short circuit as the reference time. The control unit can then calculate the value x(t) for the current position of the wire electrode 152, for example, depending on the conveying speed vF(t), using the following formula (the minus sign before the integral results from the previously described choice of signs for x(t) and vF(t)): )^^^^, or depending on the conveying path sF(t) can be calculated according to the following formula (the minus sign before the sF(t) term results in the previously described choice of signs for x(t) and sF(t)): ^^^^, where C(I(t)) represents a phenomenologically determined melting rate of the wire electrode 152 depending on the current I(t), which can be stored, for example, in the memory of the control unit 114. The melting rate can, in particular, take into account that the melting material of the wire forms a droplet at the wire end whose diameter is smaller than the length of the wire segment melted to form it. For simplification, a melting rate independent of the current C(I(t)) = const. can also be assumed, or the melting rate can be neglected C(I(t)) = 0 m / min. SE / sw 240837WO August 28, 2025. Since it can be assumed that the wire electrode 152 is just touching the melt 202 at the onset of the short circuit, the values ​​x(t) calculated with the above formula for the respective current position of the wire electrode 152 correspond approximately to the distance of the wire electrode 152 from the melt pool surface.Neglecting the deposition rate leads to a continuous deviation between the calculated value of x(t) and the actual position of the wire electrode tip relative to the weld pool. This deviation can, however, be compensated for by a suitable selection of the predefined position. Furthermore, the reference position can be regularly recalculated, for example, at each short-circuit occurrence, so that the values ​​of x(t) are regularly calibrated and / or adjusted to the actual position of the weld pool surface. Alternatively, instead of the position at short-circuit occurrence, another reference position can be used, such as the position of wire electrode 152 at short-circuit resolution, a position averaged from the positions of wire electrode 152 at short-circuit occurrence and short-circuit resolution, or a position averaged over the position of the wire electrode at short-circuit occurrence and / or short-circuit resolution of several past welding cycles.These different reference positions typically differ slightly from one another, for example due to the dynamics of the weld pool, the arc pressure, or surface tension effects during the interaction of the weld pool and the wire electrode 152. The control of the feed rate vF(t) and the welding current I(t) by the control unit 114 in the individual phases of the welding cycle is now described below: SE / sw 240837WO August 28, 2025 Short-circuit approach phase KS-AP (Phase I): The welding cycle begins with the short-circuit phase and thus with the occurrence of the short circuit (time t1 in Fig. 3). At the time of the short circuit occurrence and also for a certain time after the short circuit occurrence, the wire electrode 152 moves towards the weld pool 202 and thus enters the weld pool 202.During this short-circuit approach phase KS-AP, the control unit 114 controls the wire electrode feeder 186 after detecting the short circuit, reducing the feed rate vF(t) until the direction reverses, thus decelerating the wire electrode 152. Furthermore, as previously described, the control unit 114 stores x(t1) as the reference position of the wire electrode 152 at the reference time t1, or sets x(t1) to a predetermined value in order to subsequently calculate the respective value x(t) for the current position of the wire electrode 152 from the reference time t1. The control unit 114 can, for example, set the reference position x(t1) to zero, as shown in Fig. 3, so that x(t) indicates the position relative to the reference position x(t1). The melting rate is neglected in the calculation of x(t) in this case, i.e., C(I(t)) = 0 m / min. At time t2 the conveying velocity vF(t2) = 0 m / min.The wire electrode 152 is at bottom dead center (BDC), where it is most deeply immersed in the melt pool 202. Short-circuit removal phase KS-EP (phase). After bottom dead center UT (time t2), the control device 114 causes a further negative change in the conveying velocity vF(t), so that the wire electrode 152 moves away from the melt pool 152. During this short-circuit removal phase KS-EP, the wire electrode 152 is thus pulled out of the melt pool 152 until the short circuit is cleared (time t3). In the short-circuit removal phase, the control device 114 causes a continuously decreasing (negative) acceleration on the wire electrode, which results in a continuously increasing conveying velocity, whereby the rate of increase in conveying velocity, i.e., the acceleration of the wire electrode, decreases.The rate of change of the feed rate is preferably set such that the (negative) feed rate continues to increase in magnitude over a predetermined distance traveled by the wire electrode since the short circuit occurred, determined by x(t), or over a predetermined time period since the short circuit occurred. The predetermined time period can, for example, be at least 3 ms, and preferably at least 3.5 ms. In this way, the wire electrode is moved away from the melt pool at an ever-increasing rate for a sufficiently long distance or time period to clear the short circuit. If the short circuit has not cleared by the end of the specified time period, the feed rate vF(t) can be further increased, decreased, or maintained until the short circuit clears.Arc Removal Phase LB-EP (Phase III): Upon short-circuit resolution (time t3), the arc ignites between wire electrode 152 and workpiece 200, and the wire electrode 152 moves away from the melt pool until it reaches top dead center (TDC), at which point the wire electrode 152 is at its greatest distance from the melt pool. From the moment the short-circuit resolution is detected, the control unit 114 continuously compares the value x(t) for the current position of the wire electrode 152 with a predetermined distance value xC (Phase IIIa). Only when the value x(t) for the current position reaches or exceeds the distance value xC, i.e., a predetermined position, does the control unit 114 reduce the (negative) conveying speed vF(t), i.e., decelerate the wire electrode 152 (Phase IIIb).If xC is already exceeded at the time of short-circuit resolution, the control unit 114 reduces the conveying speed immediately after the short-circuit resolution. This position-dependent control of the conveying speed ensures that the wire electrode 152 is moved quickly away from the melt pool to a predetermined minimum distance. This positively influences the melt pool dynamics. The control unit 114 then further reduces the conveying speed vF(t) until the direction reverses, i.e., until the top dead center (TDC) is reached. Additionally or alternatively, the control unit 114 can also control the conveying speed vF(t) after the short-circuit resolution, depending on x(t), so that the top dead center (TDC) is reached at a predetermined value xOT. In addition or alternatively to the conveying speed vF(t), the control unit 114 can, after reaching or exceeding the TDC,Exceeding the distance value xC also changes the welding current I(t), in particular triggering a melting current pulse to melt the wire electrode, optionally after a predetermined time has elapsed since reaching or exceeding the distance value xC. In this way, the melting current pulse for melting a droplet can be synchronized to the wire position. Preferably, the control device 114 adjusts the rate of change of the feed rate, i.e., the acceleration of the wire electrode 152, such that the top dead center is reached after a predetermined time (ΔtOT) following short-circuit resolution (t3), thereby resulting in a more uniform welding process. SE / sw 240837WO 28.August 2025 Arc Approach Phase LB-AP (Phase IV): After reaching top dead center OT, the control unit 114 causes a (further) increase in the conveying speed vF(t) so that the wire electrode 152 moves again towards the melt pool 202, optionally after a predetermined holding time of the wire electrode 152 at the dead center. The rate of the conveying speed increase, i.e., the acceleration of the wire electrode towards the melt pool 202, can be constant or variable. In particular, the wire electrode 152 can be accelerated up to a first predetermined speed vF_1 and then held constant at vF_1. From the reversal of direction at top dead center OT (Phase IVa), the control unit 114 compares the value x(t) for the current position of the wire electrode 152 with a predetermined distance value xD. If the value x(t) for the current position reaches the distance value xD, i.e., a predetermined position, orIf the feed rate falls below a certain threshold, the control unit 114 causes the feed rate vF(t) to be changed in magnitude (Phase IVb). The feed rate vF(t) can thus be selectively changed when the wire electrode 152 is at a predetermined distance from the melt pool 202. In Phase IVb, the feed rate vF(t) can be reduced, for example, as shown in Fig. 3, to a predetermined lower speed value vF_2. This allows for a greater wire distance to the workpiece and prevents the wire electrode from being unnecessarily immersed in the melt pool during the impending short circuit. Furthermore, decelerating the wire electrode causes the liquid phase on the wire to move towards the melt pool faster than the solid phase of the decelerated wire electrode due to its inertia.This stretches the liquid phase along the wire, facilitating droplet detachment. The increased velocity of the liquid phase compared to the solid phase (SE / sw 240837WO, August 28, 2025) also leads to a rapid spread of the contact areas between the droplet and the melt pool 202. vF_2 can, for example, be in the range of 15–60 m / min. Alternatively, the conveying velocity vF(t) in phase IVb can also be increased, for example, to a predetermined higher velocity value. In this way, the short circuit can be actively initiated mechanically. Furthermore, increasing the conveying velocity also results in a higher final velocity of the droplet, ensuring a secure bond between the droplet and the melt pool, thus achieving rapid spread of the contact area between the droplet and the melt pool. By reducing orIncreasing the conveying velocity vF(t) in phase IVb allows the dynamics and shape of the liquid phase at the wire electrode or the droplet to be influenced, thus positively affecting the subsequent short-circuit phase. In particular, a high velocity of the liquid phase can be achieved through these measures. The control unit 114 can be configured to predict the time t6 at which the value x(t) for the current position reaches or exceeds the distance value xD and to adjust the change in the conveying velocity vF(t), i.e., the acceleration of the wire end 152, in phase IVa such that the time t6 lies within a predetermined range, for example, relative to the short-circuit resolution (t3). In this way, for example, the duration of the arc phase LBP can be kept largely constant. Furthermore, the kinetic energy used to initiate the short circuit can be controlled in this way.In addition to or as an alternative to the feed rate vF(t), the control unit 114 can also change the welding current I(t) after reaching or falling below the distance value xD. In this way, the welding current intensity can be synchronized with the wire position and / or the wire acceleration, i.e., with the rate of change of vF(t), or dvF(t) / dt. For example, when the distance value xD is reached or fallen below, the termination of an ongoing melting current pulse can be initiated to prevent premature droplet detachment. Phase IV or IVb ends with the next short circuit (time t7). With the end of phase IV or IVb, the welding cycle also ends, and the next welding cycle begins with phase I (so).Since the melting of the wire electrode 152 is neglected when determining x(t), meaning that the actual position of the wire end shortly before the short circuit deviates from the calculated value x(t), and since a droplet transfer occurs at the moment of the short circuit, further shortening the wire electrode, the short circuit only occurs at a position x(t7) < 0 mm. By using the short-circuit onset t7 as the new reference position and, for example, setting x(t7) = 0 mm, the control unit again provides a fairly accurate value for the wire position in the subsequent welding cycle. Increasing vF(t) in phase IVb leads to an upward shift of the liquid phase on the wire electrode. In this way, a high melting current can be used without a droplet detaching from the wire electrode. The shift of the liquid phase thus enables the use of higher arc currents.In this way, the heat input into the weld pool can be adjusted, and higher deposition rates can be achieved, among other things. Additionally, the waveform of the melting current pulse can be modified so that position-dependent influences can be compensated for, depending on the value for the current wire position. SE / sw 240837WO August 28, 2025. Furthermore, the control unit 114 can change the welding current I(t) during the short-circuit phase depending on the value for the current position of the wire electrode. For example, the short-circuit current can be regulated in this way depending on the position of the wire in the weld pool in order to influence the pinch forces on the wire. Fig. 4 shows further welding cycles SZn, SZn+1 of the welding process from Fig. 3. Diagrams (a) to (e) in Fig. 4 correspond to diagrams (a) to (e) from Fig. 3. The control unit 114 continues to control the process as described above for Fig. 3. The phases and highlighted points in Fig.The 4 are labelled with the same designations as the corresponding phases and points in Fig. 3. As already described for Fig. 3, the control unit 114 sets the current wire position as the new reference position at each short-circuit occurrence (in Fig. 4 at time tKSn, tKSn+1, or tKSn+2) and sets the value x(t) to 0 mm at the respective short-circuit time tKSn, tKSn+1, or tKSn+2. In this way, x(t) is calibrated and adjusted to the position of the weld pool surface at the time of the short circuit at the beginning of each welding cycle. As explained previously for Fig. 3, the melting of the wire electrode and the droplet transfer during the short circuit, which are not taken into account when determining x(t), lead to deviations between x(t) and the actual position of the wire end relative to the weld pool surface over the course of the welding cycle. Therefore, x(t) in Fig. 4 shows a jump at the time of the short circuit, since the control unit sets x(tKS) to zero. In Fig.Figure 4 clearly shows the position-dependent control of the feed rate vF(t) in Phase IV. As explained above for Phase IV, the control unit 114 compares the value x(t) for the current position of the wire electrode 152 with a predetermined distance value xD from the top dead center (TDC) and changes, in particular reduces, the feed rate vF(t) when x(t) falls below the distance value xD. As the comparison of welding cycles SZn and SZn+1 in Figure 4 shows, this ensures that the feed rate vF(t) is reduced at approximately a constant distance to the subsequent short circuit, regardless of the TDC height. With the TDC of welding cycle SZn+1 being higher than that of welding cycle SZn, the feed rate remains constant for a longer period due to the position-dependent control before it is reduced. This results in a more uniform welding process.At the beginning of Phase III, the predetermined position xC has already been reached or exceeded in welding cycles SZn and SZn+1. Therefore, after the short circuit is cleared, the control unit 114 immediately transitions to Phase IIIb. Fig. 5 shows further welding cycles SZm and SZm+1 of the welding process from Fig. 3 and Fig. 4, respectively. Diagrams (a) to (e) in Fig. 5 correspond to diagrams (a) to (e) in Fig. 3. The control unit 114 continues to control the process as described above for Fig. 3. The phases and highlighted points in Fig. 4 are labeled with the same designations as the corresponding phases and points in Fig. 3. As previously described, the control unit 114 sets the current wire position as the new reference position at each short-circuit occurrence (in Fig. 5 at time tKSm, tKSm+1 or tKSm+2) and sets the value x(t) to 0 mm at the respective short-circuit time tKSm, tKSm+1 or tKSm+2. In Fig.Figure 5 clearly shows the position-dependent control of the feed rate vF(t) in Phase III. As described above for Figure 3, in Phase III, after short-circuit resolution, the control unit 114 compares the value x(t) for the current position of the wire electrode 152 with a predetermined distance value xC and reduces the feed rate vF(t) in magnitude if x(t) exceeds the distance value xC. In the welding cycles SZm and SZm+1 in Figure 5, the short-circuit phase is quite short. This means that the predetermined distance value xC (compared to the welding cycles SZn and SZn+1 in Figure 4) is only reached after a longer period of time, and the reduction in magnitude of the feed rate vF(t) is correspondingly delayed. As the comparison of the welding cycles SZm and SZm+1 in Figure 5 shows, the short-circuit phase is quite short.Figure 5 shows that this time period differs between SZm and SZm+1 because, in welding cycle SZm, the wire electrode still has a longer distance to travel at the time of short-circuit resolution than in welding cycle SZm+1 to reach the predetermined position xc. Figures 4 and 5 further illustrate the position-dependent control of the welding current I(t). As described above for Figure 3, in phase III, after a predetermined time period has elapsed since reaching or exceeding the distance value xC by x(t), the control unit 114 triggers a melting current pulse to melt the wire electrode. In phase IV, after a predetermined time period has elapsed since reaching or falling below the distance value xD, the melting current pulse is terminated to prevent premature droplet detachment. The welding device 100 in Figure 1 is a welding device for manual welding.The teaching described here is not limited to welding equipment for manual welding; rather, the welding equipment can also be for automated welding, for example, using a welding robot. The same applies to the described control device and the described method. Reference list: 100 Welding equipment 110 Welding power source 112 Power unit SE / sw 240837WO 28.August 2025 114 Control unit 115 Microprocessor 116 Memory 118 Electrical output 119 Cable 122 User interface 150 Wire feeder 152 Wire electrode 154 Wire electrode supply 156 Primary wire electrode feeder 160 Control unit 162 Input 164 Inlet 165 Gas line 166 Shielding gas source 168 Torch connection 169 Valve 180 Welding torch 182 Torch section 184 Hose assembly 185 Wire guide 186 Secondary wire electrode feeder 187 Feed speed and / or feed path detection device 188 Torch trigger 190 Wire storage 192 Spring-loaded roller 200 Workpiece 202 Melt pool SE / sw 240837WO August 28, 2025.

Claims

August 28, 2025 Patent Claims 1. Method for arc welding with a consumable wire electrode (152) comprising a plurality of welding cycles (SC), each having a short-circuit phase (SC) and an arc phase (ARC), - in which the wire electrode (152) is fed at a variable feed rate (vF(t)) and - in which the feed rate (vF(t)) and / or the welding current (I(t)) is changed depending on a value (x(t)) for the current position of the wire electrode (152), in particular when the value (x(t)) for the current position of the wire electrode (152) reaches, in particular exceeds or falls below, a predetermined position (xC, xD). 2.A method according to claim 1, characterized in that the arc phase (LBP) comprises an arc approach phase (LB-AP) in which the wire electrode (152) is conveyed towards a weld pool (202), and during the arc approach phase (LB-AP) the conveying speed (vF(t)) and / or the welding current (I(t)) is changed depending on a value (x(t)) for the current position of the wire electrode (152).

3. A method according to claim 1 or 2, characterized in that the value (x(t)) for the current position of the wire electrode (152) is determined depending on a reference position of the wire electrode (152) and the conveying speed (vF(t)) or a conveying path (sF(t)). - 2 - 4. A method according to any one of claims 1 to 3, characterized in that the reference position is determined depending on the position of the wire electrode (152) at the time of short-circuit inception and / or short-circuit resolution of the current and / or a previous welding cycle (SC).

5. A method according to any one of claims 1 to 4, characterized in that the short-circuit phase (SCP) comprises a short-circuit removal phase (SC-RP) in which the wire electrode (152) is moved away from the weld pool (202), wherein the conveying velocity (vF(t)) of the wire electrode (152) is increased in magnitude during the course of the short-circuit removal phase (SC-RP), preferably with decreasing acceleration. 6.A method according to claim 5, characterized in that the conveying speed (vF(t)) of the wire electrode (152) is increased in magnitude during the short-circuit removal phase (KS-EP) until a predetermined time has elapsed since the short circuit occurred or, if short-circuit resolution occurs before the predetermined time has elapsed, until the short-circuit resolution.

7. A method according to any one of claims 1 to 6, characterized in that the arc phase (LBP) comprises an arc removal phase (LB-EP) in which the wire electrode (152) is conveyed away from the melt bath (202), wherein the conveying speed (vF(t)) of the wire electrode (152) is reduced in magnitude during the arc removal phase (LB-EP) until the direction is reversed, preferably only from a time point that depends on the value (x(t)) for the current position of the wire electrode (152). SE / sw 240837WO August 28, 2025. - 3 - 8. Method according to claim 7, characterized in that the rate at which the feed rate (vF(t)) of the wire electrode (152) is reduced in magnitude during the arc removal phase (LB-EP) until the direction reversal is adjusted such that the direction reversal is reached after a predetermined time period since short-circuit resolution.

9. Method according to claim 7 or 8, characterized in that the feed rate (vF(t)) of the wire electrode (152) is maintained in magnitude less than or equal to a predetermined speed value in the region of the direction reversal for a predetermined time period. 10.A method according to any one of claims 1 to 9, characterized in that the method comprises a plurality of pulsed welding cycles without a short-circuit phase (SCP), wherein preferably a parameter of a pulsed welding cycle following a welding cycle (SC) with a short-circuit phase (SCP) is set depending on the value (x(t)) for the current position of the wire electrode (152).

11. Control device (114) for a welding apparatus (100) with at least one microprocessor (115) and at least one memory (116) containing instructions, the execution of which on the at least one microprocessor causes an arc welding process to be carried out according to a method according to any one of claims 1 to 10.

12. Welding apparatus (100) comprising a control device (114) according to claim 11. SE / sw 240837WO August 28, 2025.

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