METHOD FOR CONTROLLING AND / OR REGULATING A PULSE ARC WELDING PROCESS AND WELDING DEVICE FOR CARRYING OUT A PULSE ARC WELDING PROCESS

Description

[0001] The invention relates to a method for controlling and / or regulating a pulsed arc welding process with a consumable welding wire on a workpiece, wherein current pulses are periodically applied with a predetermined welding frequency and a pulse current increased compared to a base current to form an arc and detach droplets of the molten welding wire, and the consumable welding wire is moved towards the workpiece at a predetermined forward speed, the welding wire is moved away from the workpiece at a predetermined backward speed after a short circuit between the welding wire and the workpiece is detected, and the welding wire is moved back towards the workpiece after the short circuit between the welding wire and the workpiece is detected breaking up.

[0002] Furthermore, the invention relates to a welding device for carrying out a pulsed arc welding process, comprising a welding power source, a welding torch for supplying a consumable welding wire to a workpiece and a control device for controlling and / or regulating welding parameters during the pulsed arc welding process.

[0003] EP 3 782 756 B1 and US 9,035,220 B2 describe short-arc welding processes in which arc phases and short-circuit phases alternate periodically. The droplet of the consumable welding wire transfers to the workpiece during the short-circuit phase.

[0004] The invention relates to welding processes using consumable welding wire (MIG / MAG welding processes), specifically pulsed welding processes and spray arc welding processes, in which the welding wire is fed towards the workpiece at a substantially constant feed rate and current pulses are periodically applied to assist droplet detachment. Pulsed arc welding processes are used for various materials (steel, stainless steel, aluminum) in different power ranges, particularly at higher deposition rates and in automated welding processes for sheet thicknesses of approximately 2 mm and above. Variants of pulsed welding processes are also included, such as AC pulsed welding processes in which the welding current is reversed to a negative value during the base current phase, or pulsed welding processes in which additional current waveforms are applied alongside the current pulses and base current phases.Two-wire solutions, in which two welding wires are used, can also fall under the scope of the present invention. For example, in the so-called twin welding process, two independently operating arc welding processes with two welding wires are combined in one process.

[0005] In pulsed arc welding, periodic current pulses with a predetermined welding frequency and a pulse current higher than a base current are applied to the consumable welding wire. This causes the droplet to constrict ("pinch effect") and ultimately detach as droplets of molten welding wire material. Ideally, the transition of the droplet from the end of the welding wire to the workpiece occurs "in transit" without forming a short circuit between the welding wire and the workpiece. However, particularly at small distances between the free end of the welding wire and the surface of the workpiece being welded, i.e., with short arc lengths, short circuits between the welding wire and the weld pool during the detachment of the droplet of molten material from the welding wire cannot be avoided.The closer the arc's point of origin is to the weld pool on the workpiece, the more likely short circuits become between the welding wire and the workpiece. These short circuits usually resolve themselves without changing the welding current before they lead to welding defects or process disruptions. This is particularly true for longer arc lengths. However, with smaller arc length variations, the short circuits can persist longer due to less constriction of the weld droplet and may not resolve spontaneously. In this case, the short circuit is broken by increasing the welding current. Increasing the current to break the short circuit causes weld spatter and instabilities in the welding process, which negatively impact weld quality. It is crucial to resolve the short circuit before the next current pulse, as otherwise the weld spatter and instabilities will have a particularly pronounced effect.

[0006] JP 2014 083553 A describes a method for controlling a pulsed arc welding process according to the preamble of the claim. 1.

[0007] EP 1 677 941 B2 describes a method for controlling a pulsed arc welding process in which the position of the welding wire end relative to the workpiece is determined, thus enabling precise control of the arc length. A short circuit between the welding wire and the workpiece is detected. After the short circuit breaks, the welding wire can be moved away from the workpiece to a fixed or adjustable distance.

[0008] A pulsed arc welding process with alternating polarity of the welding current and the welding voltage has been disclosed, for example, in JP 2002086271 A.

[0009] EP 3 431 214 B1 describes a combination of a short-arc welding process with a pulsed arc welding process. During the pulsed arc welding process, the welding wire is fed towards the workpiece at a constant forward speed.

[0010] US Patent 8,124,913 B2 also deals with a combination of different welding processes to optimally control the heat input into the workpiece.

[0011] The object of the present invention is to provide the aforementioned method and welding device by which any short circuits occurring between the welding wire and the workpiece can be kept as short, constant, or stable as possible, so that the weld quality and the stability of the welding process are affected as little as possible. This should be achieved without current pulses, or at least without strong current pulses. The effort required for this should be kept to a minimum. Disadvantages of the prior art should be avoided or at least reduced.

[0012] The problem according to the invention is solved by a method described above for controlling and / or regulating a pulsed arc welding process, in which the welding wire is moved towards the workpiece at a predetermined initial increased forward speed for a predetermined initial duration and / or a predetermined initial distance, and then moved again towards the workpiece at the predetermined forward speed after the breaking of the short circuit between the welding wire and the workpiece is detected. Upon detection of a short circuit between the welding wire and the workpiece, the welding wire is moved away from the workpiece at a defined reverse final speed, thereby assisting in the resolution of the short circuit. This occurs more rapidly the greater the acceleration of the welding wire's feed rate from the usual forward movement to the reverse movement and the higher the defined reverse speed.As soon as the short circuit is broken, the movement of the welding wire is reversed to a forward direction, i.e., towards the workpiece. This requires only the ability to detect the short circuit between the welding wire and the workpiece, which can be easily implemented using the welding parameters that are typically already monitored, in particular the welding voltage or arc voltage. Additionally, a suitable feed device is needed to advance the welding wire, enabling dynamic movement of the welding wire both towards and away from the workpiece. The control system according to the invention prevents or compensates for a greater distance between the end of the welding wire and the workpiece, and thus a greater arc length, when the arc is reignited after the brief backward movement of the welding wire. This does, however, slightly increase the control system complexity.Highly dynamic drives can be implemented, for example, using gearless direct motors located directly in the welding torch. The control method according to the invention helps to keep the short circuits between the welding wire and the weld pool, which inevitably occur particularly with very short arc lengths in pulsed arc welding processes, as constant and stable as possible, so that the weld quality and the stability of the welding process are affected as little as possible. In particular, the backward movement of the welding wire prevents the short circuit from still existing when the next current pulse begins, which would have a particularly negative impact on the quality of the weld.

[0013] The short circuit between the welding wire and the workpiece is preferably detected by a drop in the welding voltage, in particular by a drop in the welding voltage below a predetermined voltage limit. The predetermined voltage limit can be, for example, 12 V and can be varied depending on the materials used and the welding wire diameter.

[0014] According to a further feature of the invention, the welding wire is moved away from the workpiece at a predetermined reverse speed, which corresponds to 1 to 100 times the predetermined forward speed. The higher the reverse speed and the acceleration, the faster a detected short circuit will be interrupted. This places correspondingly higher demands on the wire feed rate.

[0015] If the welding wire is moved towards the workpiece at a predetermined second increased forward speed before a short circuit between the welding wire and the workpiece is detected, the short circuit can be forced and thus kept stable or constant.

[0016] The predetermined second increased feed rate of the welding wire is preferably triggered by the start of the current pulse by setting a predetermined second time interval before or after the start of the current pulse. The faster movement of the welding wire towards the workpiece reduces the arc length and promotes the occurrence of a short circuit as soon as possible after the current pulse occurs or after the droplet detaches from the welding wire. The duration of the welding wire's movement at the predetermined second increased feed rate can be determined by a predetermined third time interval or a predetermined second path length.

[0017] Advantageously, the welding wire is moved towards the workpiece at a first increased or second increased forward speed that is 1 to 100 times higher than the specified forward speed.

[0018] According to one embodiment of the inventive method, the welding wire is moved towards the workpiece at the predetermined first increased forward speed for a predetermined initial duration and / or a predetermined initial distance. This initial speed depends on the duration of the welding wire's reverse movement after the short circuit is detected, preferably 50% to 95%, and particularly preferably 70% to 80%. The duration during which the welding wire is moved at the predetermined initial increased forward speed is thus determined by the duration of the welding wire's reverse movement after the short circuit with the workpiece is detected.

[0019] If a predetermined initial time delay is observed after a short circuit between the welding wire and the workpiece is detected, and only then is the welding wire moved away from the workpiece at the predetermined reverse speed (if the short circuit is still detected), erroneous short circuit detection can be prevented. This initial, predetermined, and adjustable time delay at the start of the welding wire's reverse movement prevents the welding wire from reversing if only very brief short circuits occur that break themselves. Ideal values ​​for the predetermined initial time delay are, for example, in the range of 0.1 ms to 0.5 ms.

[0020] Similarly, a predetermined second time delay can be observed after the short circuit between the welding wire and the workpiece is detected. Only then, if the short circuit is still detected, can the welding wire be moved back towards the workpiece. This second, predetermined and adjustable time delay at the start of the forward movement after the backward movement of the welding wire allows the backward movement to be maintained for a certain period to ensure that the welding wire movement is only reversed back towards the workpiece once the short circuit has been reliably broken. Ideal values ​​for the predetermined second time delay could, for example, be in the range of 0.1 ms to 0.5 ms.

[0021] The welding current can be increased to a higher short-circuit current than the base current or reduced to a lower short-circuit current than the base current during the backward movement of the welding wire during the short circuit between the welding wire and the workpiece.

[0022] The increase can be, in particular, 10% to 90% compared to the preset base current, and the reduction can also be, in particular, 10% to 90% compared to the preset base current.

[0023] The welding frequency, at which the current pulses are applied periodically, is typically between 1 Hz and 500 Hz. Depending on the welding frequency used, the period is between 2 ms and 1 s. Therefore, it must be ensured that any short circuit that occurs is broken no later than the next current pulse. This can be achieved with the highly dynamic feed motors mentioned above, such as direct drives.

[0024] Suitable values ​​for the reverse speed of the welding wire are between 1 m / min and 120 m / min, in particular between 15 m / min and 50 m / min.

[0025] Suitable welding wire acceleration values ​​are between 33.3 m / s² and 4000 m / s², particularly between 500 m / s² and 750 m / s². Higher values ​​require highly dynamic feed motors, such as gearless direct drives.

[0026] The problem according to the invention is also solved by a welding device mentioned above, the control unit of which is designed to control and / or regulate a process described above. For the advantages achievable thereby, reference is made to the above description of the process for controlling and / or regulating a pulsed arc welding process. Since the described process is implemented primarily in software form, the corresponding effort and thus the costs remain within limits.

[0027] The present invention is explained in more detail with reference to the accompanying drawings. These show: Fig. 1 a block diagram of a welding device for carrying out a pulsed arc welding process with a consumable welding wire according to the prior art; Fig. 2 the time profiles of the welding current, the welding voltage, the wire feed rate and the position of the end of the welding wire with respect to the workpiece in an ideal pulsed arc welding process; Fig. 3 the time profiles of the welding current, the welding voltage, the wire feed rate and the position of the end of the welding wire with respect to the workpiece in a pulsed arc welding process with an undesirably long short circuit between the welding wire and the workpiece and a current increase to break the short circuit according to the prior art; Fig.4. The time profiles of the welding current, welding voltage, wire feed speed, and the position of the end of the welding wire relative to the workpiece during a pulsed arc welding process in the event of a short circuit between the welding wire and the workpiece; Fig. 5. The time profiles of the welding current, welding voltage, wire feed speed, and the position of the end of the welding wire relative to the workpiece during a pulsed arc welding process using an embodiment of the method according to the invention in the event of a short circuit between the welding wire and the workpiece; Fig.6 the temporal profiles of the welding current, the welding voltage, the wire feed rate and the position of the end of the welding wire in relation to the workpiece during a pulsed arc welding process using a further embodiment of the method according to the invention, in which the formation of a short circuit between the welding wire and the workpiece is forced by a faster forward movement of the welding wire; and Fig. 7 a variant of the method according to . Fig. 6 .

[0028] Fig. 1 Figure 1 shows a block diagram of a welding device 1 for performing a pulsed arc welding process with a consumable welding wire 4 according to the state of the art. The welding torch 3 is connected via a hose assembly 6 to a welding power source 2 and a wire spool 7 for the consumable welding wire 4. The welding power source 2 contains a power unit 8, which provides the necessary welding current I and welding voltage U and delivers them to the welding wire 4 in the welding torch 3. A control unit 9 provides the necessary parameters for the welding process and controls and regulates the welding process accordingly. During the welding process, an arc L burns between the free end of the welding wire 4 and the workpiece W.In pulsed arc welding, current pulses IM with an increased pulse current IP are periodically applied to the consumable welding wire 4, causing a constriction ("pinch effect") of the droplet due to the resulting magnetic field and finally the detachment of droplets T of the molten welding wire material and a transition into the weld pool on the workpiece W.

[0029] Fig. 2 This figure shows the time-dependent behavior of the welding current I, the welding voltage U, the wire feed rate vD, and the position of the end of the welding wire 4 relative to the workpiece W during an ideal pulsed arc welding process. According to a predetermined welding frequency f or pulse frequency, current pulses IM with a pulse current IP higher than the base current IG are periodically applied to the consumable welding wire 4, causing the constriction and detachment of the droplet T of molten welding wire material. The transfer of the droplet T from the end of the welding wire 4 to the workpiece W occurs "floating" without the formation of a short circuit KS between the welding wire 4 and the workpiece W. The arc L burns continuously between the end of the welding wire 4 and the surface of the workpiece W, and the welding wire 4 is moved towards the workpiece W at a constant forward velocity vD,V.

[0030] Fig. 3 This figure shows the time-dependent behavior of the welding current I, the welding voltage U, the wire feed rate vD, and the position of the end of the welding wire 4 relative to the workpiece W during a pulsed arc welding process with an undesirably long-lasting short circuit KS between the welding wire 4 and the workpiece W. After the short circuit KS occurs between the welding wire 4 and the workpiece W, which can be detected by a drop in the welding voltage U, the welding current I is increased, for example, in a ramp-like manner, to cause or assist the short circuit KS to break up. When the short circuit KS breaks up, the higher welding current I results in weld spatter S, which negatively affects the quality and stability of the welding process.After the short circuit KS is broken, the welding process continues with the basic current IG until, according to the welding frequency f, the next current pulse IM with the pulse current IP is applied to detach the next droplet T from the welding wire 4.

[0031] Fig. 4 This diagram shows the time-dependent behavior of the welding current I, the welding voltage U, the wire feed rate vD, and the position of the end of the welding wire 4 relative to the workpiece W during a pulsed arc welding process when an unwanted short circuit KS occurs between the welding wire 4 and the workpiece W. After the detection of a short circuit KS, the welding wire 4 is moved away from the workpiece W at a predetermined reverse speed vD,R. The predetermined reverse speed vD,R can be, for example, 1 to 100 times the predetermined forward speed vD,V, for example, between 1 m / min and 120 m / min, and in particular between 15 m / min and 50 m / min. The detection of the short circuit KS between the welding wire 4 and the workpiece W is achieved simply by detecting a drop in the welding voltage U, in particular a drop in the welding voltage U below a predetermined voltage limit UGR, for example, 12 V.The welding wire 4 is moved away from the workpiece W at the specified reverse speed v D,R until the short circuit KS breaks, which is detected, for example, by the welding voltage U or by exceeding the specified voltage limit U GR. After the short circuit KS between the welding wire 4 and the workpiece W breaks, the welding wire 4 is moved back towards the workpiece W. In the illustrated embodiment, the forward movement of the welding wire 4 is again at the specified forward speed v D,V that was used before the short circuit KS.The change in the feed rate vD of the welding wire 4 from the predetermined forward rate vD,V to the predetermined reverse rate vD,R and the change back from the predetermined reverse rate vD,R to the predetermined forward rate vD,V occurs as quickly as possible, i.e., with an acceleration (vD / ΔtD) of preferably 33.3 m / s2 to 4000 m / s2, in particular from 500 m / s2 to 750 m / s2. This is possible with highly dynamic feed motors, for example, gearless direct drives.

[0032] During the reverse movement of the welding wire 4 during the short circuit KS between the welding wire 4 and the workpiece W, the welding current I can be increased to a higher short-circuit current I KS' than the base current IG before the short circuit KS, in particular to a short-circuit current I KS' that is 10% to 90% higher than the preset base current IG. This reduces the duration of the short circuit KS and increases the arc pressure after reignition. Likewise, during the reverse movement of the welding wire 4, the welding current I can be reduced to a lower short-circuit current I KS" than the base current IG before the short circuit KS, in particular to a short-circuit current I KS" that is 10% to 90% lower than the preset base current IG. This reduces weld spatter.The choice of the amplitude of the higher short-circuit current IKS' and the lower short-circuit current IKS" depends on many factors, particularly the material or shielding gas used, the operating point, and the characteristic curve. Increasing the current can ensure that the short circuit KS breaks in time and that the stability of the system is maintained.

[0033] According to a variant shown in dashed lines, a predetermined initial time delay Δt D1, preferably 0.1 ms to 0.5 ms, can be observed after a short circuit KS between welding wire 4 and workpiece W is detected, and only then is the welding wire 4 moved away from the workpiece W at the predetermined reverse velocity v D,R, provided the short circuit KS is still detected. This prevents the erroneous detection of a short circuit KS or the reversal of the welding wire movement when only very short short circuits KS occur.

[0034] Furthermore, a predefined second time delay Δt D2, preferably 0.1 ms to 0.5 ms, can optionally be waited after the breaking of the short circuit KS between welding wire 4 and workpiece W is detected. Only then, if a breaking of the short circuit KS is still detected, is the welding wire 4 moved again towards workpiece W. This second predefined and adjustable time delay Δt D2 of the start of the forward movement after the backward movement of the welding wire 4 allows the backward movement to be maintained for a certain period of time to ensure that the welding wire movement is only reversed towards workpiece W once the short circuit KS has been reliably broken. The first time delay Δt D1 and the second time delay Δt D2 can be set independently of each other.The choice of the first time delay Δt D1 and the second time delay Δt D2 also depends on the operating point, i.e., the operating conditions (voltage U, current I, and other characteristic curves) of the system. Depending on the operating point, it may be advantageous to increase the current I later or earlier, since the time at the base current IG is limited.

[0035] Fig. 5 Figure 1 shows the time profiles of the welding current I, the welding voltage U, the wire feed rate vD, and the position of the end of the welding wire 4 relative to the workpiece W during a pulsed arc welding process using an embodiment of the inventive method when a short circuit KS occurs between the welding wire 4 and the workpiece W. In this variant, the welding wire 4 is moved towards the workpiece W for a predetermined first time duration Δt1 and / or a predetermined first distance Δx1 at a predetermined first higher forward speed vD,VB1 and then moved again towards the workpiece W at the predetermined forward speed vD,V after the breaking of the short circuit KS between the welding wire 4 and the workpiece W is detected.This measure prevents or compensates for a greater distance between the end of the welding wire 4 and the workpiece W, and thus a greater arc length L, when the arc L is reignited after the brief backward movement of the welding wire 4. The specified initial increased forward velocity v D,VB1 is, for example, 1 to 100 times higher than the specified forward velocity v D,V before the short circuit KS.

[0036] The predetermined initial time duration Δt 1 can be made dependent on the time duration Δt VR of the backward movement of the welding wire 4, for example, 50% to 95%, particularly preferably 70% to 80% of the time duration Δt VR of the backward movement of the welding wire 4. The same effect can also be achieved via the distance Δx that the welding wire 4 travels during the backward movement and the percentage thereof that travels back towards the workpiece W.

[0037] Finally, it shows Fig. 6 The temporal profiles of the welding current I, the welding voltage U, the wire feed rate v D, and the position of the end of the welding wire 4 relative to the workpiece W during a pulsed arc welding process using a further embodiment of the method according to the invention, in which the formation of a short circuit KS between the welding wire 4 and the workpiece W is forced by a faster forward movement of the welding wire 4 in order to keep the arc L particularly short. Accordingly, the welding wire 4 is moved towards the workpiece W with a predetermined second increased forward speed v D,VB2 before the expected short circuit KS between the welding wire 4 and the workpiece W is detected. The forward movement of the welding wire 4 with the predetermined second increased forward speed v D,VB2 takes place, for example, over a predetermined third time period Δt 3.The welding wire 4 is then slowed down again to its normal, lower forward speed VD,V and moved at this speed towards the workpiece W. This forces the formation of the short circuit KS as soon as possible after the current pulse IM or the detachment of the droplet and keeps the short circuit KS as stable as possible. After the short circuit KS is resolved, the welding process is continued, for example, according to [reference to relevant section]. Fig. 5 continued.

[0038] In the variant according to Fig. 7 The predefined second increased feed rate v D,VB2 is triggered from the start of the current pulse IM. The predefined second time duration Δt 2 can be either positive or negative, meaning the predefined second increased feed rate v D,VB2 can begin before or after the start of the current pulse IM. In the illustrated embodiment according to Fig. 7 The forward movement of the welding wire 4 is no longer slowed down, but is maintained at the predetermined second increased feed rate v D,VB2 until a short circuit KS is detected. Afterwards, the reverse movement of the welding wire 4 according to the invention continues at the predetermined reverse speed v D,R until the short circuit KS breaks. Thereafter, the welding process continues according to... Fig. 4 continued.

[0039] The invention also relates to a welding device 1 for carrying out a pulsed arc welding process, comprising a welding power source 2, a welding torch 3 for supplying a consumable welding wire 4 to a workpiece W and a control device 9 for controlling and / or regulating welding parameters during the pulsed arc welding process, which control device 9 is designed for controlling and / or regulating a method described above.

[0040] The invention avoids quality losses of a weld seam and instabilities during the welding process and is relatively easy and inexpensive to implement.

Claims

1. Method for regulating and / or controlling a pulse arc welding process, with a consumable welding wire (4) on a workpiece (W), wherein, in order to form an arc (L) and detach droplets (T) of the consumable welding wire (4), current pulses (IM) are periodically applied at a predetermined welding frequency (f) and an increased pulse current (IP) compared to a base current (IG), and the consumable welding wire (4) is moved at a predetermined forward speed (vD,V) in the direction of the workpiece (W), the welding wire (4) is moved away from the workpiece (W) at a predetermined reverse speed (vD,R) after a short-circuit (KS) between the welding wire (4) and the workpiece (W) is detected, and the welding wire (5) is moved again in the direction of the workpiece (W) after a breaking of the short-circuit (KS) between the welding wire (4) and the workpiece (W) is detected, characterized in that the welding wire (4) is moved toward the workpiece (W) for a predetermined first duration(Δt1) and / or a predetermined first distance (Δx1) at a predetermined first increased forward speed (vD,VB1) towards the workpiece (W) and is then moved again at the predetermined forward speed (vD,V) towards the workpiece (W) after the breaking of the short-circuit (KS) between the welding wire (4) and the workpiece (W) is detected.

2. Method according to claim 1, characterized in that the welding wire (4) is moved away from the workpiece (W) at a predetermined reverse speed (vD,R) that corresponds to 1 to 100 times the predetermined forward speed (vD,V).

3. Method according to any one of claims 1 or 2, characterized in that the welding wire (4) is moved toward the workpiece (W) at a predetermined second increased forward speed (vD,VB2) before a short-circuit (KS) between the welding wire (4) and the workpiece (W) is detected.

4. Method according to claim 3, characterized in that the welding wire (4) is moved a predetermined second time period (Δt2) before or after the start of the current pulse (IM) and / or a predetermined third time period (Δt3) and / or a predetermined second distance (Δx2) at the predetermined second increased forward speed (vD,VB2) in the direction of the workpiece (W) before a short-circuit (KS) between the welding wire (4) and the workpiece (W) is detected.

5. Method according to any one of claims 1 to 4, characterized in that the welding wire (4) is moved toward the workpiece (W) at a first increased forward speed (vD,VB1) or second increased forward speed (vD,VB2) that is 1 to 100 times higher than the predetermined forward speed (vD,V).

6. Method according to any of claims 1 to 5, characterized in that the welding wire (4) is moved the predetermined first time period (Δt1) and / or predetermined first distance (Δx1) at the first increased forward speed (vD,VB1) in the direction of the workpiece (W), which is dependent on the duration (ΔtVR) of the reverse movement of the welding wire (4) after the detection of the short-circuit (KS), preferably 50 % to 95 %, particularly preferably 70 % to 80 % of the duration (ΔtVR) of the reverse movement of the welding wire (4).

7. Method according to any one of claims 1 to 6, characterized in that a predetermined first time delay (ΔtD1), preferably 0.1 ms to 0.5 ms, is maintained after a short-circuit (KS) between the welding wire (4) and the workpiece (W) is detected, and only thereafter is the welding wire (4) moved away from the workpiece (W) at the predetermined reverse speed (vD,R) if the short-circuit (KS) is still detected.

8. Method according to any one of claims 1 to 7, characterized in that a predetermined second time delay (ΔtD2), preferably 0.1 ms to 0.5 ms, is maintained after the breaking of the short-circuit (KS) between the welding wire (4) and the workpiece (W) is detected, and only thereafter is the welding wire (5) moved again in the direction of the workpiece (W) if a breaking of the short-circuit (KS) is still detected.

9. Method according to any one of claims 1 to 8, characterized in that during the reverse movement of the welding wire (4) during the short-circuit (KS) of the welding wire (4) to the workpiece (W), the welding current (I) is increased to a higher short-circuit current (IKS'), in particular to a short-circuit current (IKS') that is higher by 10 % to 90 % compared to the preset base current (IG).

10. Method according to any one of claims 1 to 8, characterized in that during the reverse movement of the welding wire (4) during the short-circuit (KS) of the welding wire (4) to the workpiece (W), the welding current (I) is reduced to a lower short-circuit current (IKS") in particular to a short-circuit current (IKS") that is 10 % to 90 % lower than the preset base current (IG).

11. Method according to any one of claims 1 to 10, characterized in that the welding wire (4) is moved away from the workpiece (W) at a reverse speed (vD,R) of between 1 m / min and 100 m / min, in particular between 15 m / min and 50 m / min, after the short-circuit (KS) between the welding wire (4) and the workpiece (W) is detected.

12. Method according to any one of claims 1 to 11, characterized in that the change of the feed rate (vD) of the welding wire (4) is carried out with an acceleration (ΔvD / Δt) between 33.3 m / s2 and 4000 m / s2, in particular between 500 m / s2 and 750 m / s2.

13. Welding device (1) for carrying out a pulse arc welding process, with a welding current source (2), a welding torch (3) for supplying a consumable welding wire (4) to a workpiece (W), and a control device (9) for regulating and / or controlling welding parameters during the pulse arc welding process, characterized in that the control device (9) is designed for regulating and / or controlling a method according to one of claims 1 to 12.