Adjustment of interval bonding method

Abstract

This allows for more precise control of the heat input introduced to the workpieces to be joined during arc interval joining. [Solution] During the interval joining method of arc, the first pause duration (TP1) of the first pause stage (PP1) is determined, and the determined first pause duration (TP1) is set to a predetermined target pause duration (TP soll If there is a difference between the first pause duration (TP1) and a predetermined target pause duration (TP soll The difference between the first pause stage (PP1) and the second pause duration (TP2) of the second pause stage (PP2) which follows the first pause stage (PP1) over time, is compared, and a predetermined target pause duration (TP soll To minimize the difference between the two values, at least one joining parameter of the arc interval joining method that affects the pause duration of the pause phase (PP) is modified.

Description

[Technical Field]

[0001] The present invention relates to an arc interval joining method comprising a series of arc phases and pause phases, wherein the arc phase has a predetermined arc duration and alternates with the pause phase over time, and during the arc phase, a joining current flows between the joining electrode and the workpiece for joining the workpiece, and no joining current flows during the pause phase. Furthermore, the present invention relates to a welding apparatus for implementing the arc interval joining method, wherein the welding apparatus comprises a welding torch that introduces energy to a welding or brazing location on a workpiece to form a molten pool, and the welding apparatus comprises a feeding unit that supplies welding wire to the molten pool, melts the welding wire within the region of the molten pool by the introduced energy to create a welded joint in the workpiece, and the welding apparatus comprises a control device that controls the welding apparatus. [Background technology]

[0002] Arc interval welding and arc interval brazing are two widely used joining processes that are particularly suitable for regulating the temperature distribution within the joined workpiece or for controlling the heat input introduced into the workpiece during arc welding or arc brazing. Below, we will discuss arc interval welding and arc interval brazing, using the general term "arc interval joining" to refer to both methods collectively.

[0003] Arc interval joining has an arc phase and a pause phase. In the arc phase, an arc discharges (at least temporarily) between the joining electrode and the workpiece, while in contrast, during the pause phase, the arc does not discharge to reduce heat introduction. In the arc phase, a joining current flows, introducing heat into the workpiece to be joined. On the other hand, in the pause phase, the workpiece does not receive heat input due to the lack of arc discharge and therefore the lack of joining current, so it can be cooled and release heat.

[0004] Because the temperature field generated within a workpiece during joining affects a range of quality factors, including thermal deformation within the joined workpiece, or various metallurgical properties within the joined workpiece, such as grain boundary structure or seam quality, adjusting the heat input to the workpiece to be joined is extremely important, especially when welding or brazing thin plates. As described above, the amount of heat introduced into the workpiece during arc interval joining can be influenced by matching the duration of the arc phase and the pause phase, thereby adjusting the temperature distribution within the joined workpiece. The ability to adjust the temperature field, which directly affects the aforementioned quality factors, is a key reason to use arc interval joining instead of alternative joining methods.

[0005] In the patent literature, arc interval welding, in particular, is treated as an important variation of interval joining. Specifically, Patent Document 1 (DE2214192A1) describes interval welding in which interruptions in the welding phase are provided to achieve cooling of the welded workpiece. In contrast, Patent Document 2 (EP3744460A1) modifies the duration of the so-called "arc ON" and "arc OFF" phases to impart a predetermined shape to the resulting weld joint. Patent Document 3 (EP2810732A2) further teaches recording the time from the start of a short circuit to the first ignition of the arc, and then initiating re-ignition of the arc after a defined reference time.

[0006] In general, in the case of interval arc joining, as with the prior art approach described above, both the duration of the arc phase (hereinafter referred to as "arc duration") and the duration of the pause phase (hereinafter referred to as "pause duration") depend on two types of time points. On the one hand, the time when the arc extinguishes (hereinafter referred to as "arc extinction time") is important, and on the other hand, the time when the arc is relit (hereinafter referred to as "litting time") plays an important role. In the pause phase described above, the arc is extinguished at the extinction time at the start of the pause phase, and the arc is relit at the litting time at the end of the pause phase. Therefore, the pause duration of the relevant pause phase occurs in the period between the extinction time and the litting time immediately following this extinction time. Conversely, the period between the litting time and the extinction time immediately following this litting time defines the arc duration of the relevant arc phase. The durations of the arc phase and pause phase are typically in the range of 300 milliseconds to 500 milliseconds. Therefore, the arc duration and pause duration may be 250 milliseconds, 300 milliseconds, 350 milliseconds, 400 milliseconds, 450 milliseconds, or 500 milliseconds. However, depending on the application, longer or shorter arc and / or pause stages may occur (e.g., even shorter than 100 milliseconds).

[0007] Furthermore, in order to determine the duration of the arc phase and the pause phase, it is necessary to determine the extinction and ignition times that occur during the arc interval joining process. In this regard, it has been recognized that determining the extinction time is usually a problem that can be easily solved in practice. Since maintaining the arc requires supplying voltage to the joining electrode used for welding or brazing, arc extinction can be easily achieved by interrupting and / or short-circuiting this voltage supply, which can be done with high time accuracy with little technical effort.

[0008] In contrast, determining the timing of ignition is often complex and can involve various difficulties depending on the situation. In metal shielded gas welding such as MIG welding or MAG welding, or in MIG brazing or MAG brazing, arc re-ignition (short-circuit ignition) can occur due to electrical contact between the molten joining electrode (e.g., the molten welding wire electrode) and the workpiece during welding. When the joining electrode contacts the workpiece for re-ignition, re-ignition can be caused, as is known, by a high ignition current, or by pulling the arc up by removing the welding electrode or joining electrode from the workpiece during arc ignition ("pull-in arc re-ignition").

[0009] The question of when the arc will actually reignite in such a situation is influenced by several factors, including the distance the joining electrode must travel during the pause phase before re-contacting the workpiece (hereinafter referred to as the "approach distance"), the so-called approach speed at which the joining electrode moves toward the workpiece during the pause phase, the surface condition of the workpiece to be welded, or the magnitude of the welding voltage applied for re-ignition. When these factors fluctuate, the resulting ignition time also fluctuates as a direct consequence. Therefore, the actual ignition time may differ from a predetermined target ignition time.

[0010] Even when firing an arc between the joining electrode of a welding or brazing apparatus and a workpiece in a non-contact manner, accurately determining or predicting the final firing time is often difficult. In the case of non-contact firing, a firing voltage pulse can be applied to ionize the region between the joining electrode and the workpiece so that the arc is fired within the ionized region between the joining electrode and the workpiece. In this case, firing failures can occur, i.e., insufficient ionization may be obtained, and therefore an arc may not be formed, in which case it is necessary to try re-firing with another firing voltage pulse after a pause. In such cases, a time-dependent deviation occurs, and therefore, as with contact firing, the firing time will vary.

[0011] As described above, variations in the ignition time can occur during arc interval joining. These variations in ignition time lead to variations in the duration of the pause, with a difference of 1 ms to 400 ms observed between the desired pause duration and the actual pause duration. This means that the amount of heat introduced into the welded or brazed workpiece varies, potentially differing from a predetermined target heat amount, resulting in an undesirable temperature distribution. As explained earlier, the temperature distribution within the workpiece is directly related to various quality factors, and consequently, an undesirable temperature distribution can lead to defects in the weld joint, brazing defects, undesirable thermal deformation, or undesirable metallurgical properties. While these interrelationships and difficulties are well known, the prior art has not provided any adequate solutions to this problem. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] German Patent Application Publication No. 2214192 [Patent Document 2] European Patent Application Publication No. 3744460 [Patent Document 3] European Patent Application Publication No. 2810732 [Overview of the project] [Problems that the invention aims to solve]

[0013] Therefore, the object of the present invention is to more precisely control the heat input to the workpiece being joined during arc interval joining. [Means for solving the problem]

[0014] This problem is solved by the features of the independent claim. Specifically, the independent claim relates to the arc interval joining method and welding apparatus described at the beginning, In the arc interval joining method, the duration of the first pause in the first pause phase is determined, If the determined first pause duration differs from a predetermined target pause duration, the difference between the first pause duration and the predetermined target pause duration is compared, and at least one bonding parameter of the arc interval bonding method that affects the pause duration of the pause stage is changed so that the difference between the second pause duration of the second pause stage (which occurs later in time) and the predetermined target pause duration becomes smaller. This is the plan.

[0015] The procedure according to the present invention makes it possible to intentionally adapt the arc duration and pause duration to a predetermined, desired, or required value of the heat input that needs to be introduced into the workpiece to be joined during the arc interval joining method. To this end, a predetermined target pause duration is favorably adapted to the heat input to be introduced, and can be determined, for example, from the heat input to be introduced by a predetermined mathematical relationship. In this way, the joining quality achievable with the arc interval joining method can be significantly improved.

[0016] The first and second pause stages can essentially be arbitrarily selected pause stages during the arc interval joining method, but it should be noted that this is conditional on the second pause stage occurring later in time than the first pause stage. Therefore, the first and second pause stages do not necessarily have to be the absolute first and absolute second pause stages in the arc interval joining method, but may be pause stages that occur later in the progress of the arc interval joining method. Furthermore, the second pause stage does not necessarily have to be the pause stage immediately following the first pause stage. There may be one or more additional pause stages between the first and second pause stages.

[0017] In this invention, it has been found that the bonding current generated during the interval arc bonding method is particularly suitable for distinguishing between the arc phase and the pause phase. This is because, for example, even when using a pulsed arc, the bonding current usually flows continuously during the arc phase (for example, the bonding current flows during the arc phase even when the arc is interrupted by a short circuit between the welding wire and the workpiece. This is because, in particular, the bonding voltage usually still exists even in the event of a short circuit during the arc phase). In an advantageous manner, the arc can also continue to discharge continuously during the arc phase. During the pause phase, no bonding current flows, and the arc does not discharge. Therefore, the arc phase can be understood as the phase in which the bonding current flows. By considering the bonding current, the arc phase and the pause phase can be distinguished in a reliable manner.

[0018] In practice, there are relatively rare special arc welding methods in which the joining current can be interrupted, even during the arc phase, particularly for short periods of time. These particularly short periods of time are typically less than 10 milliseconds, less than 5 milliseconds, or less than 0.5 milliseconds. Phases in which the joining current flows, and are therefore interrupted for very short periods, i.e., less than 10 milliseconds, advantageously less than 5 milliseconds, or less than 0.5 milliseconds, are also considered arc phases within the scope of these descriptions. Thus, a pause phase can be interpreted as a phase in which the joining current does not flow, preferably longer than 10 milliseconds, longer than 20 milliseconds, or longer than 50 milliseconds.

[0019] In a more advantageous method, as explained at the beginning, the arc interval joining method may also be an arc interval welding method or an arc interval brazing method, in which, during the arc phase, an arc discharge occurs between the joining electrode and the workpiece at least temporarily, preferably continuously, and the joining current for joining flows from the joining electrode due to the arc discharge between the joining electrode and the workpiece.

[0020] In the usual practice of adjusting the technical system, the determination of the first pause duration can be performed sequentially; that is, not only is the first pause duration determined at one point in time during the interval joining method of the arc, but these are performed multiple times, preferably at points separated from each other at predetermined intervals over time. Each pause duration thus determined may serve as a starting point for modifying joining parameters to bring subsequent pause durations closer to a predetermined target pause duration. These relationships are, of course, well known to those skilled in the art of control engineering. In this procedure, in order to be able to react quickly and immediately to the difference between the determined pause duration and the predetermined target pause duration, it may be intended that there are fewer than 100 pause stages, or fewer than 50 pause stages, or fewer than 10 pause stages PP, or fewer than 5 pause stages, or no pause stages at all, between the determination point in time when the pause duration is determined and the adjustment point in time when at least one joining parameter is changed.

[0021] Within the scope of the present invention, rather than directly determining or directly measuring the duration of the pause in question, in order to determine the first pause duration, at least one parameter value of at least one descriptive parameter of the arc interval joining method that describes the first pause duration is determined. It is often advantageous to determine a first pause duration from this at least one determined parameter value, i.e., to perform an indirect determination or measurement of the pause duration according to the present invention. In this way, the present invention can be used even in scenarios where direct measurement of the pause duration is not possible, for example, because only limited sensor technology is available.

[0022] Furthermore, as descriptive parameters for indirect determination, in particular, During the pause phase, in particular, the start point when the wire feed is restarted and / or the voltage for supplying the bonding electrodes increases again, The firing time immediately after the start The period between It can be determined as a parameter value for a descriptive parameter. Alternatively, it is possible to determine the approach distance the welding wire travels between the start time and the firing time immediately following the start time. I found out.

[0023] As previously stated, the arc discharge interval joining method according to the present invention may, advantageously, be a MIG welding method or a MAG welding method in which a welding wire that melts in the arc phase is provided as the joining electrode, or a MIG brazing method or a MAG brazing method in which molten solder is provided as the joining electrode. When molten solder is used in the MIG brazing method or MAG brazing method, this is called "melt brazing using temporarily liquefied solder," in which case the molten solder forms a liquid phase and thus forms a molten pool. In all cases, a molten pool is formed on the workpiece within the area of ​​the joining by an arc that discharges at least temporarily between the joining electrode and the workpiece, and this is the same in welding and brazing. There are differences in the details of molten pool formation in each case, but in other words, in welding, the base material and filler material, i.e., the workpiece and the welding electrode, are melted, while in brazing, only the filler material and not the workpiece are melted. In both welding and brazing, a joining electrode is supplied to form the weld joint, brazed joint, and ultimately the molten pool, and the introduced energy melts the joining electrode. Therefore, the molten pool corresponds to the liquid phase of the filler material and / or the material within the area of ​​the joint.

[0024] In the implementation of the joining method according to the present invention (as a welding method or a brazing method), at the start of the pause phase of both welding and brazing, the arc is extinguished and wire feeding is stopped, and wire feeding is restarted at the start time after the pause interval in the pause phase. The period between the start time and the firing time immediately following the start time is determined as the parameter value of the description parameter, and / or, The approach distance the welding wire travels between the start time and the ignition time immediately following the start time is determined as the parameter value of the descriptive parameter.

[0025] Advantageously, the following joining parameters can be used and thus modified: wire feed rate, and / or joining current during the arc phase, and / or activation time, and / or the distance between the welding wire and the workpiece at activation, and / or the period between arc extinction and activation, and / or the current-time area during the arc phase.

[0026] In particular, the combination of determining the approach distance as a parameter value of the descriptive parameter and changing the junction current in the arc phase as a junction parameter of the arc interval junction process was found to be advantageous for adjusting the pause duration to a target pause duration. This is because, in many cases, the approach distance can be determined accurately and intuitively with little effort, and in many cases, for example, the level of the junction current in the arc phase can be changed easily and with little effort.

[0027] The present invention will be described in more detail below with reference to Figures 1 to 4b, which illustrate and schematicly illustrate advantageous embodiments of the present invention, and are not limiting. [Brief explanation of the drawing]

[0028] [Figure 1] Figure 1 shows a typical structure of a welding apparatus. [Figure 2] Figure 2 shows a schematic overview of the arc interval joining method according to prior art. [Figure 3a] Figure 3a shows a schematic overview of the arc interval joining method according to the present invention. [Figure 3b] Figure 3b shows the interval arc joining method according to the present invention, including changes in joining current and wire feeding speed. [Figure 4a]Figure 4a shows a bonding plan for implementing the bonding method according to the present invention. [Figure 4b] Figure 4b shows a bonding plan for implementing the bonding method according to the present invention. [Modes for carrying out the invention]

[0029] The present invention is described in more detail below using MSG welding apparatus 1 for metal shielding gas welding (MSG welding), which includes, in particular, well-known methods of metal inert gas welding (MIG welding) and metal active gas welding (MAG welding). However, it should be noted that the present invention is by no means limited to the field of metal shielding gas welding and can be similarly used in the field of tungsten inert gas welding (MIG welding) or any other welding technique.

[0030] As is well known, the MSG welding apparatus 1 under consideration can also be used for arc brazing. As will be explained in detail below, in order to perform the brazing process with the MSG welding apparatus 1, it is sufficient to use a shielding gas SG suitable for brazing and solder suitable for brazing as the filler material, i.e., solder suitable for brazing as the molten joining electrode 7. No other changes, such as changes to the welding torch 4, are necessary, so the control of the MSG welding apparatus 1, as shown in Figure 1, does not differ during brazing and welding. Therefore, the present invention can also be used in interval brazing performed with the MSG welding apparatus 1 shown in Figure 1, and as a result, the following description can be applied to both welding and brazing with necessary modifications. To emphasize this, the following will use the general terms joining current I, joining voltage U, joining electrode 7, etc., instead of the terms welding current I, brazing voltage U, brazing electrode 7, etc., which are normally used in welding and brazing, respectively.

[0031] The MSG welding apparatus 1 comprises a power supply 2, a hose package 3, a welding torch 4, and a shielding gas container 5 containing shielding gas SG. The shielding gas container 5 is connected to the welding torch 4 via a shielding gas line 8. A pressure controller (not shown) can be provided in the shielding gas container 5 or the shielding gas line 8, for example, in the form of a known coupling component, and this pressure controller usually regulates the flow of shielding gas SG. Depending on the material of the base metal G, either a less reactive, inert shielding gas SGi, such as argon (Ar) or helium (He), or an active shielding gas SGa, such as oxygen (O) or carbon dioxide (CO2), is used. In welding methods that do not use shielding gas, the shielding gas container 5 and the shielding gas line 8 can, of course, be omitted. For MSG brazing, a mixed gas consisting of argon, carbon dioxide, and hydrogen is usually used as the shielding gas SG.

[0032] Within the power supply 2, a joining electrode 7 can be placed in the form of welding wire 7a, which is normally wound on a welding wire reel 13. A feeding unit 12, driven by a feeding drive unit 12a, is provided to unwind the welding wire 7a and, in particular, to feed the welding wire 7a to the joining point, i.e., to the welding location in the case of welding, and to the brazing location in the case of brazing.

[0033] For brazing using the MSG welding apparatus 1, hard solder such as silver solder, brass solder, or copper-based solder can be used instead of welding wire 7a, or soft solder such as tin solder, which can also be wound from the welding wire reel 13, can be used. These relationships are well known to those skilled in the field of joining technology.

[0034] Furthermore, the welding wire 7a on the welding wire reel 13, as well as the feeding unit 12, can be located in a unit separate from the power source 2 and outside of the power source 2. As is well known, there are also embodiments of the welding apparatus 1 that include multiple feeding units 12, which are adapted to mutually advantageous ways to provide the necessary wire feeding. However, the feeding units 12 can also be located in the area of ​​the joining electrode 7. These do not limit the applicability of the present invention.

[0035] The wire feed drive unit 12a is controlled by the control unit 14, which typically communicates with the user interface 17. Through the user interface 17, the user can, for example, specify the joining voltage U, joining current I, and the wire feeding speed v at which the welding wire 7a is fed to the joining point. d For example, specific joining parameters can be set as needed. A predetermined welding program containing specific joining parameters can be saved in the control unit 14, which can be selected by the user via the user interface 17 or by a higher-level control device such as the control device of a welding robot.

[0036] Furthermore, the power supply 2 houses a power supply unit 15, which is controlled (or regulated) by a control unit 14 and connected to an external voltage source 16. Thus, the control unit 14 can be configured to control and / or regulate specific components of the MSG welding device 1, such as the entire MSG welding device 1 or the feed unit 12, the shielding gas supply, and / or the power supply unit 15, and / or the movement of the welding torch 4. The control unit 14 can be implemented in the form of microprocessor-based hardware, a microcontroller, or an integrated circuit (ASIC, FPGA), and can, of course, be located outside the power supply 2.

[0037] The power supply unit 15 of power supply 2 supplies the welding torch 4 with the necessary joining current I and joining voltage U via power lines 19 located within the hose package 3. To weld, the joining voltage U is applied to the joining electrode 7, resulting in the joining current I flowing during the arc discharge. Furthermore, welding wire 7a and shielding gas SG, and possibly a cooling medium for cooling the welding torch 4, are also typically supplied to the welding torch 4 via the hose package 3 (using the supply unit 12). Control cables may also be provided within the hose package. However, multiple individual cables for each medium, control, and energy may be provided as the hose package 3.

[0038] To perform a welding or brazing process, a first potential is applied to a workpiece 6 made of a base material G via an electrical connection 18, and a second potential is applied to the welding wire 7a as the joining electrode 7, so that after the arc 11 is lit, a joining current I flows between the welding wire 7a and the workpiece 6. In this case, various types of arcs can be used, such as short-circuit arcs, transfer arcs, spray arcs, pulsed arcs, or cold metal transfer ("CMT") arcs, which are well known to those skilled in the art of joining technology. Specifically, during welding, the arc 11 melts the welding wire 7a and the base material G, creating a material bond between the molten welding wire 7a and the base material G. In the illustrated example, a weld joint 10 is welded to the workpiece 6, which is called a build-up weld. However, as shown by the dashed line, two workpieces 6, 6a can also be connected, which is called a joint weld. The arc 11 flows around the welding torch 4 in the form of a bell-shaped shielding gas 9, shielding the molten material within the weld joint 10 from the surrounding environment. However, it should be noted that, in principle, welding or brazing can be performed without using shielding gas SG. In this case, the shielding gas container 5 and shielding gas line 8 can be omitted.

[0039] In welding methods using non-melting joining electrodes, such as WIG welding, the welding wire 7a is supplied to the arc and melts within the arc, during which an arc discharge occurs between the joining electrode and the workpiece.

[0040] The welding wire 7a, i.e., the joining electrode 7 that melts, has a specific wire feeding speed v that may depend on several influencing values. d The wire is then fed to the joint. In manual welding, where the welding torch 4 is guided by a person, generally, for example, a constant wire feeding speed v is used depending on the set joining current I. d This is selected. In an automated welding method, for example, when the welding torch 4 is guided by a welding robot, the wire feeding speed v d For example, the welding speed v at which the welding torch 4 is moved relative to the workpiece 6. s Additional options can be selected depending on the circumstances.

[0041] As shown in Figure 1, the interval joining method according to the present invention can be used in an MSG welding apparatus 1 in a manner advantageous for welding or brazing, and can be performed automatically or manually.

[0042] To generate the necessary arc stage LP (where joining occurs, i.e., welding or brazing takes place) and the pause stage PP (where joining does not occur, i.e., welding or brazing does not take place) that periodically alternates with the arc stage LP (see Figure 2), as described above, at the start of the pause stage PP, it is necessary to first extinguish the discharging arc 11 and stop the wire feed. Stopping the wire feed is done by controlling the wire feed speed v d This means reducing it to zero, and to achieve this, the rotational motion of the welding wire reel 13 in the welding apparatus shown in Figure 1 must be braked. Since the welding wire reel 13 has physical inertia, the transition of the wire feeding speed to zero does not occur instantaneously.

[0043] As described above, the arc extinction of the arc 11 can be performed comfortably and accurately over time, particularly by interrupting the bonding voltage U. Stopping the wire feeding or reducing the wire feeding speed usually causes no problems. At that time, the reduction of the wire feeding speed can be started precisely at the start of the pause stage PP, or can be started a little before the start of the pause stage PP, or can be started a little after the start of the pause stage PP. These relationships will be described in detail later.

[0044] In many cases, the welding wire 7a continues to burn for a short time, particularly in the region of the end of the welding wire 7a facing the workpiece 6, typically with a high amount of heat accumulated, even after the arc 11 has extinguished during the so-called combustion period. This combustion affects, in addition to any movement of the welding wire 7a by the feeding unit 12, the remaining distance between the axial end of the welding wire 7a and the workpiece 6, the so-called approach distance s d at the start of the pause stage PP, specifically affecting the distance between the end of the welding wire 7a facing the workpiece 6 and the workpiece 6.

[0045] Also, as described above, it has been found that the re-ignition of the arc 11 is often more difficult than arc extinction. Specifically, for arc re-ignition during short-circuit arcing, an electrical contact between the welding wire 7a and the workpiece 6 is required. However, in the pause stage PP, the wire feeding is first reduced to zero and the welding wire 7a moves away from the workpiece 6 by the approach distance s d so that in order to move the welding wire 7a again in the direction of the workpiece 6, it is necessary to first restart the wire feeding in the pause stage PP. In this case, in order to enable stable re-ignition of the arc ११, a wire feeding speed v d lower than that in the arc stage LP, called the "approach speed" in welding technology, is usually used.

[0046] In the pause phase PP, the point at which wire feeding restarts, and which is usually the point at which the voltage U applied to the junction electrode 7 increases again for re-ignition, is referred to in this patent application as the start-up time TA. The start-up time TA divides the pause phase PP into two intervals. The interval between the arc extinction time TL at the start of the pause phase PP and the start-up time TA is referred to below as the stop interval ΔR, and the interval following the start-up time TA until the arc 11 is re-ignited at the ignition time TZ is referred to as the start-up interval ΔA. Similar to the arc extinction time TL, these points for the start-up time TA can also be set with high accuracy over time (the start-up of the power supply unit 15 or the wire feed drive unit 12a is usually only negligibly disruptive). Therefore, a target value can be set for the duration of the stop interval ΔR that can be achieved with high accuracy with little effort in practice.

[0047] Based on the considered start time TA, in particular, the approach distance s that the welding wire 7a must travel to the start time TA within the start interval ΔA during the pause phase PP after wire feeding restart. d It can be seen that this becomes a decisive influencing factor at the time of re-ignition, i.e., at the ignition point. The obvious reason for this is the wire feed speed v d If constant, different approach distances s d This is because the time it takes to travel to these locations varies.

[0048] On the other hand, the approach distance s that should be moved d This depends on the distance the welding wire 7a burns after the end of the arc phase LP, i.e., the length of the welding wire 7a that burns further due to the heat accumulated in the welding wire 7a. Accordingly, the end of the welding wire 7a facing the workpiece 6 should then move further away or closer to the workpiece 6, depending on the burning, by the approach distance s. d It is increased or decreased. Therefore, the approach distance s dThis is the distance between the end of the welding wire 7a facing the workpiece 6 and the workpiece 6 at the start time TA. Of course, the changing surface profile of the workpiece 6 as the welding torch 4 moves is also a factor, as is the approach distance s. d This may affect the approach distance s. Similarly, the movement of the welding wire 7a through the feeding unit 12 is affected. d It could have an impact.

[0049] Typically, the voltage U applied to the welding wire 7a begins to increase at the start time TA, and since a high voltage U is already applied at the time of re-contact, re-ignition usually occurs immediately after the welding wire 7a and workpiece 6 make re-contact. Specifically, re-ignition occurs when the welding wire 7a is lifted again and the arc 11 is pulled up. Therefore, the time of re-contact between the welding wire 7a and workpiece 6 and the ignition time TZ that occurs after the pause phase are very close to each other and are therefore often considered identical as an initial approximation. Thus, variations in the time of re-contact between the welding wire 7a and workpiece 6 lead to variations in the ignition time TZ at which the arc 11 is re-ignited at the end of the pause phase PP. Even with high-voltage ignition, the remaining approach distance s depends on the applied (high) ignition voltage U. d Breakdown occurs and re-firing is triggered only when the approach distance s is given at the start of the firing interval ΔA, similar to the case of short-circuit firing. d It depends on [something]. Therefore, the same problem occurs here.

[0050] To visualize these relationships, Figure 2 shows the bonding current I, bonding voltage U, and wire feeding speed v that may occur in a conventional interval bonding method, for example, in the MSG welding apparatus 1 shown in Figure 1. d This shows the approximate time course of the joining parameters. In arc stages LP1, LP2, and LP3, pulsed joining voltage U and pulsed joining current I are used, but of course, this is not necessary and is merely an example of welding during the arc stage. Wire feed rate vd The value v is between arc stages LP1, LP2, and LP3. dL The junction voltage U and the resulting junction current I are also initially reduced to zero at the start of the pause phases PP1 and PP2. To ensure that the arc 11 is relit at the end of the pause phases PP1 and PP2, wire feeding toward the workpiece 6 is restarted at each start time TA1 and TA2 during the pause phases PP1 and PP2, initially at a slower wire feeding speed v dP However, this is used as the approach speed. In this embodiment, the voltage U is also increased again at the start times TA1 and TA2 so that the arc 11 can be immediately relit when the welding wire 7a and the workpiece 6 make re-contact.

[0051] Furthermore, from the progress shown in Figure 2, it can be seen that the arc stage LP exists between the ignition time TZ when arc 11 is lit and the extinction time TL when arc 11 is extinct, and the pause stage PP exists between the extinction time TL and the ignition time TZ. Furthermore, the target pause duration TP soll A mechanism is established, and in this case, the actual duration of the pause phases PP1 and PP2 is defined as the target pause duration TP. soll It is desirable to match it as accurately as possible.

[0052] However, it can be inferred, in particular, from the drawn second pause stage PP2, that this criterion is not always met in practice. The duration of the second pause stage PP2 is significantly longer than the duration of the first pause stage PP1, and the given target pause duration TP soll There is a significant difference. In this case, due to reasons such as a change (increase) in the combustion of the welding wire 7a, a longer approach distance s is required. d This must be moved. Considering the chain of effects described at the beginning—"pause duration - introduced heat - weld seam defect"—such a difference is highly undesirable.

[0053] To at least mitigate the problems described with reference to Figure 2, the present invention, During the arc interval joining method, the intention is to determine the first pause duration TP1 of the first pause stage PP1. The determined first pause duration TP1 is a predetermined target pause duration TP soll If there is a difference, the first pause duration TP1 and a predetermined target pause duration TP soll The difference between the first pause stage PP1 and the second pause duration TP2 of the second pause stage PP2, which occurs later in time, is compared with a predetermined target pause duration TP soll The intention is to modify at least one joining parameter of the arc interval joining method that affects the pause duration of the pause stage PP so that the difference between the two is reduced. By modifying at least one joining parameter according to the present invention, of course, other pause durations TP3, TP4 of other pause stages PP3, PP4 following a second pause stage PP2, etc., can also be set to a predetermined target pause duration TP soll It can be brought closer to a predetermined target pause duration TP. soll This eliminates all differences between the resulting pause durations TP2, TP3, etc.

[0054] This is shown in Figure 3a based on an embodiment of the present invention, which will be described in more detail below.

[0055] An efficient method for implementing the present invention is to directly measure the pause duration TP of the pause phase PP. As described above, the arc extinction time TL is usually known, and in welding apparatus 1 as shown in Figure 1, the ignition time TZ is often automatically monitored, for example, by monitoring the joining current I. The pause duration TP of the pause phase can be estimated from the time difference between the ignition time TZ and the preceding arc extinction time TL.

[0056] In welding methods where the arc 11 is extinguished, wire feed is reduced, and the wire feed speed becomes zero at the start of the pause phase PP, the duration of the pause phase PP can be determined by measuring the duration of the start interval ΔA between the start time TA and the subsequent ignition time TZ. As mentioned above, the start time TA can be determined with high accuracy, and as a result, the duration of the pause interval ΔR is usually known. If the durations of both the pause interval ΔR and the start interval ΔA in the pause phase PP are known, the duration of the pause phase PP TP can be estimated by a simple sum.

[0057] However, directly measuring the duration of the activation interval ΔA is not always necessary. In this invention, the approach distance s traveled by the welding wire 7a during the past activation interval ΔA is considered. d It was recognized that the same determination could be made. This information is directly available to the control unit 14 for controlling the feed drive unit 12a, in fact, when relevant. The wire feed speed v used in the pause phase PP. dP Since this is naturally known, the associated duration of the start interval ΔA can be easily estimated from the path the welding wire 7a traveled after the start time TA, and in the simplest case, it can be estimated by division. The total duration of the pause phase PP is also determined in this case by adding the durations of the pause interval ΔR and the start interval ΔA. Since the welding wire usually does not move during the pause interval ΔR, the distance the welding wire 7a traveled over the entire pause period PP can also be determined.

[0058] Multiple joining parameters are available to influence and correct the pause duration TP of the pause stage PP. Specifically, within the scope of the present invention, the start time TA can be shifted over time, for example, by moving it closer to or further away from the previous extinction time TL, thereby achieving a desired correction of the pause duration TP.

[0059] Similarly, to increase or decrease the duration of the start interval ΔA, and thus correct the pause duration TP, a predetermined wire feed rate v after the start time TA is used. dP It can be increased or decreased.

[0060] Furthermore, the approach distance s is deterministic with respect to the duration of the activation interval ΔA. d It was found that this is affected by the level of the junction current I used in the previous arc stage LP. The reason for this is that a higher junction current I increases the heat stored in the welding wire 7a, which leads to greater burning of the welding wire and consequently to an increased approach distance s d This is because the approach speed v becomes larger. d The approach distance is constant s d If this changes, for obvious reasons the duration of the start interval ΔA changes directly, and therefore the resulting pause duration PP also changes.

[0061] In particularly advantageous embodiments, the aforementioned joining parameters can also be combined and modified to affect the firing time TZ.

[0062] The method according to the present invention involves a junction current I, a junction voltage U, and a wire feeding speed v. d The effect of on the time course is shown in Figure 3a. Similar to Figure 2, even when plotted in Figure 3a, a pulsed junction voltage U that generates a pulsed junction current I is used in arc stages LP1, LP2, and LP3. Similar to Figure 2, in Figure 3a, the wire feeding speed v d The value v is between arc stages LP1, LP2, and LP3. dL The junction voltage U and junction current I first decrease to zero during pause stages PP1 and PP2. The junction voltage U and junction current I also first decrease to zero at the start of pause stages PP1, PP2, and PP3. As shown in Figure 2, the pause duration of the first pause stage PP1 is set to a predetermined target pause duration TP. soll There is a significant difference.

[0063] In the subsequent second pause phase PP2, the second activation time TA2 is brought forward, i.e., shifted closer to the previous extinction time TL2. This shortens the pause interval ΔR2 compared to the first pause phase PP1, thereby making the overall pause duration TP2 of pause phase PP2 a pause period that already very precisely matches the target pause duration. In the third pause phase PP3, the temporal timing of the activation time TA3 is maintained compared to the second pause phase PP2. That is, in the third pause phase PP3, a pause interval ΔR3 of the same length as in the second pause phase PP2 is provided, resulting in a predetermined target pause duration TP soll A good agreement with this is maintained. This makes it possible to achieve a constant pause time and arc duration after only a few interval cycles.

[0064] Generally, the determination of the pause duration TP according to the present invention involves determining the first pause duration TP1 by the duration of the start interval ΔA or the approach distance s. d This can be carried out by determining a parameter value PW of the description parameter PT of the arc interval joining method that describes the first pause duration TP1, from which at least one pause duration TP1 required to carry out the present invention can be determined.

[0065] To determine the parameter value PW of the descriptive parameter PT, various methods, particularly those known from control engineering or signal processing, can be used, in which case the parameter value PW is, among other things, In particular, using filters such as Kalman filters, or In particular, using an observer such as a Rouenberger-type observer, Using an adaptive system, or This can be determined using a neural network consisting of measurements of one or more junction parameters of the arc interval junction method.

[0066] As mentioned above, the joining current I flowing through the arc stage LP affects the combustion of the welding wire 7a and the braze, which in turn affects the approach distance s in the pause stage PP. d This has a direct impact. As is well known, the energy carried by the passage of current over time arises from the current-time area covered by this passage of time. When the current-time area is large, more electrical energy is transferred, and therefore more heat is transferred, in this case into the welding wire 7a or braze, which leads to greater combustion. When the current-time area is small, the heat input decreases, and therefore less combustion occurs. Correspondingly, the heat remaining in the welding wire 7a at the end of arc stage LP, and thus combustion, and consequently the approach distance s that should be moved... d This can be controlled by appropriately changing the junction current I.

[0067] As described above, in addition to the junction current I, the approach distance s that should be covered starting from the start point TA is also included. d The wire feed speed v is what affects it. d Therefore, the approach distance s d In a particularly advantageous embodiment, the junction current I and wire feeding speed v are adjusted, and consequently, the duration TP of the pause stage PP of the target pause stage are adjusted. d These can be changed together.

[0068] However, naturally, the wire feeding speed v d Without further modification, the junction current I can be changed independently, and the wire feeding speed v can be changed independently of the change in junction current I. d Please note that you can also make changes to this independently.

[0069] The effect of changes in junction current I within the scope of the present invention is shown in Figure 3b. In the process shown in Figure 3b, the amplitude of each final junction current pulse decreases from the first arc stage LP1, which reduces the heat transferred and therefore the resulting combustion. Changes in junction current I affect wire feed speed vd To combine with the changes, in the situation shown in Figure 3b, the wire feeding speed v d A so-called "lag" is provided. This is due to the wire feeding speed v d This means that the decrease does not begin immediately at the extinction points TL2 and TL3, but rather immediately after the start of the subsequent pause phases PP2 and PP3.

[0070] In a favorable manner, when current pulses are not used in the welding or brazing method, the current-time area can be directly provided, for example, a current-time area flowing throughout the entire arc stage LP, or a current-time area flowing in the latter half of the arc stage LP. By modifying the joining current I as described above, a so-called "combustion pattern" can be implemented, and thus a predetermined melting rate of the welding wire 7a or solder can be achieved. In general, various attributes of the joining current can be changed to adjust the combustion, such as the peak value of the joining current I, the effective value of the joining current I, the pulse frequency of the joining current I, or other attributes of the joining current I.

[0071] In contrast to the situation shown in Figure 3b, the amplitude of the final junction current pulse I can also be increased to increase the remaining heat in the welding wire 7a and thus cause more combustion. Furthermore, the change in the magnitude of the junction current pulse is by no means limited to the final junction current pulse. Therefore, in the same manner, the amplitudes of multiple current pulses present at the end of the arc stage LP, for example, the amplitudes of the last two junction current pulses or the amplitudes of the last three junction current pulses, can be increased or decreased. Additionally, the wire feeding speed v d The point at which the decrease begins can not only be postponed to the subsequent pause phase, but can also be brought forward. Therefore, within the scope of the present invention, before the arc extinction time TL, the wire feed speed v can be set within the arc phase LP. d This allows us to begin reducing the approach distance s d This contributes to the increase of [something].

[0072] Furthermore, the wire feeding speed vd Regarding the time-dependent shift in the onset of reduction, it should be noted that such a shift is preferably selected to be small compared to the resulting pause duration TP and arc duration TL. "Small" means wire feed speed v d The reduction typically begins when one-tenth, one-quarter, or one-third of the pause phase PP has elapsed, and in all cases the wire feed speed v d This means that it can be set to zero within a single pause phase PP.

[0073] Changes to the junction current I and / or wire feeding speed v d When using the change, the change in the start time TA during the pause phase can be omitted, as shown in Figure 3b. However, as another control value, in addition to the junction current I, and / or the wire feeding speed v d In addition, it is also possible to change the TA at startup.

[0074] The steps of the method according to the present invention can, of course, be implemented in software, and preferably in a control unit such as the control unit 14 shown in Figure 1. When implemented in software, the processing of the steps of the method to be performed is typically performed over a predetermined sampling time T. s The discrete time point t arises from the product of the discrete index k. k =k·T s This is performed in a favorable manner, in a time-discrete implementation (and of course in an analog implementation), at a discrete decision time TE following the first pause stage PP1, the pause duration of the first pause stage PP1 is determined during the arc interval joining method, and at a discrete adjustment time TR following the decision time TE, the determined first pause duration TP1 is set to a predetermined target pause duration TP soll If there is a difference, it is intended that at least one joining parameter of the arc interval joining method that affects the pause duration TP2 of the second pause stage PP2 can be changed.

[0075] This procedure involves determining the pause duration and a predetermined target pause duration TP. soll To respond quickly and immediately to the differences between the two, it may be intended that there are no pause stages PP of less than 100, or less than 50, or less than 10, or less than 5, or no pause stages PP at all between the decision time TE and the adjustment time TR. In a particularly advantageous manner, the second pause stage PP2 can be started only after the adjustment time TR, thereby ensuring that the adaptation of the joining parameters to be changed has already been made before the new pause stage PP begins.

[0076] Ultimately, two advantageous embodiments are shown in the form of wiring diagrams in Figures 4a and 4b. In this case, Figure 4a summarizes the basic idea of ​​the present invention in the form of a standard control loop well known in adjustment techniques. According to the above description, the welding apparatus 1 represents the section to be adjusted, from which the pause duration TP occurring in the pause stage PP is determined.

[0077] The determined pause duration TP is equal to the predetermined target pause duration TP. soll Compared to the pause duration adjustment error e TP This is obtained. Pause duration adjustment error e TP This is supplied to controller R1 as an input variable, and controller R1 determines the modified start time TA as a control variable. On the other hand, the determined start time TA is used during the operation of welding equipment 1, and the actual pause duration TP is the target pause duration TP when a properly designed controller is used. soll It conforms to the requirements.

[0078] Controller R1 may be a PID controller, or a model prediction controller, or a flatness-based controller, or a backstepping controller, or a sliding mode controller, which can, of course, be implemented in discrete-time formulations in software as described above.

[0079] In a particularly advantageous embodiment of the present invention, a control law is applied to the controller R1. TA k+1 =TA k +e TP,k You can choose this. As mentioned above, the variable k represents a time-discrete index, and as a result, TA k and TA k+1 This represents two consecutive activation points. Amplification constant 1 / T S This simple control law, corresponding to an integrator having the following subsequent start time TA k+1 This is shifted precisely by the difference between the pause duration at the previous point in time and the target pause duration.

[0080] For example, the resulting adjustment error e TP,k In order to average, the above control law is: TA k+1 =TA k +B·e TP,k It can be interpolated to adjust the error e TP,k It includes a multiplicative setting parameter B for weighting.

[0081] As described above, in addition to changing the start time TA, other or additional junction parameters can also be changed to affect the duration of the pause when the pause stage PP occurs. To implement the present invention, in addition to the start time TA, the junction current I and the wire feeding speed v d One possible use of is shown in Figure 4b.

[0082] Here, as shown in Figure 4a, the determined pause duration TP is the predetermined target pause duration TP soll A first control loop is provided which is compared with the pause duration adjustment error e. TPis determined, and then the changed starting time TA is specified as the first control variable. However, the special feature of the controller R2 shown in FIG. 4b is that the controller R2 acts on two control variables, on the one hand at the starting point TA and on the other hand at the pause stage with the wire feeding speed v d that can be used. As described in detail above, the wire feeding speed v d used in the pause stage PP can be used to affect the duration between the starting point TA and the subsequent arcing point TZ. As a result, naturally, the wire feeding speed v d can also be used as a control variable for changing the duration of the starting interval ΔA. However, as shown in FIG. 3b, it is also conceivable to use the wire feeding speed v d at the end of the arc stage LP as a control variable for changing the pause duration TP.

[0083] As described in detail above, a pause duration TP that differs from the predetermined target pause duration TP soll results particularly from changing the approach distance s d . As a result, in FIG. 4b, using another controller R3, not only is the pause duration TP itself adjusted, but also the approach distance s d is determined, compared with a predetermined target approach distance s d , and then the approach distance adjustment error e s is determined, and this approach distance adjustment error e s is provided to another controller R3 for adjustment. Within the scope of the present invention, for example, by changing the bonding current I or the wire feeding speed v d , it is possible to affect the approach distance s d or adjust the approach distance s d , which has been described in detail above. Note that the lower control loop shown in FIG. 4b may be provided separately.

[0084] When designing a control loop with two or more control variables as shown in Figure 4b, all control loops should be properly tuned to different controllers R2, R3 or different control variables TA, v d Therefore, to prevent I from interfering with each other, it may also be advantageous to use control distribution methods from the field of control engineering.

Claims

1. An arc interval joining method comprising a series of arc phases (LP) and pause phases (PP), The arc phase (LP) has a predetermined arc duration and appears alternately with the pause phase (PP) over time. During the arc phase (LP), a bonding current (I) flows between the bonding electrode (7) and the workpiece (6) to bond the workpiece (6), and during the pause phase (PP), no bonding current (I) flows. In the interval joining method of the said arc, During the interval joining method of the arc, a first pause stage (PP １ ) First pause duration (TP １ ) was decided, The determined first pause duration (TP １ ), if there is a difference from the predetermined target pause duration (TP ｓｏｌｌ ), compares the difference between the first pause duration (TP １ ) and the target pause duration (TP ｓｏｌｌ ), and, as the difference between the second pause duration (TP), which is subsequent in time to the first pause stage (PP １ ), in the second pause stage (PP ２ ２ ) and the predetermined target pause duration (TP ｓｏｌｌ ) becomes smaller, at least one joining parameter of the interval joining method of the arc that affects the pause duration of the pause stage (PP) is changed An arc interval joining method characterized by the following:

2. The aforementioned arc interval joining method is an arc interval welding method or an arc interval brazing method. During the arc phase (LP), an arc (11) is discharged at least temporarily between the bonding electrode (7) and the workpiece (6), and this arc (11) causes a bonding current (I) to flow from the bonding electrode (7) to the workpiece (6) for bonding. The arc interval joining method according to feature 1.

3. The arc (11) is extinguished at the extinguishing point (TL) at the start of the pause phase (PP), and relit at the ignition point (TZ) at the end of the pause phase (PP). The pause duration (TP) of the pause phase (PP) corresponds to the time interval between the extinction time (TL) at the start of the pause phase (PP) and the firing time (TZ) at the end of the pause phase (PP). At least one joining parameter of the aforementioned arc interval joining method affects each firing time (TZ) at the end of the pause phase (PP). The arc interval joining method according to feature 2.

4. First Pause Phase (PP) １ ) First pause duration (TP １ ) is a first pause stage (PP) during the interval joining method of the arc. １ ) at the decision point after (T Ｅ ) was decided, Second Pause Phase (PP) ２ ) Second pause duration (TP ２ At least one joining parameter of the arc interval joining method that affects the arc is the determined first pause duration (TP １ ) is the predetermined target pause duration (TP ｓｏｌｌ If it differs from the decision point (T Ｅ ) Adjustment point after (T Ｒ ) was changed, Decision point (T Ｅ ) and adjustment time (T Ｒ Between ) there are fewer than 100 pause stages (PP), or fewer than 50 pause stages (PP), or fewer than 10 pause stages (PP), or fewer than 5 pause stages (PP), or there are no pause stages (PP) at all. The arc interval joining method according to any one of claims 1 to 3.

5. Second Pause Phase (PP) ２ ) is the adjustment time (T Ｒ ) followed by, The arc interval joining method according to feature 4.

6. First pause duration (TP １ To determine the first pause duration (TP), at least one parameter value (PW) of at least one description parameter (PT) of the interval joining method of the arc is determined, and this parameter value (PW) is the first pause duration (TP １ ) describe, First pause duration (TP １ ) is determined from at least one parameter value (PW) that has been determined. The arc interval joining method according to one or more of claims 1 to 5.

7. The aforementioned arc interval joining method is In the case of MIG welding or MAG welding, in the arc phase (LP), the molten welding wire (7a) is provided as the joining electrode (7), or In the case of MIG brazing or MAG brazing, the solder to be molten is provided as the joining electrode (7), Energy is introduced onto the workpiece (6) within the range of the joining area by an arc (11) that discharges at least temporarily between the joining electrode (7) and the workpiece (6) in order to form a molten pool. The bonding electrode (7) feeds the wire into the molten pool (26) at a wire feeding speed (v ｄ ) is supplied by, In order to create a welded or brazed joint (10) in the workpiece (6), the introduced energy melts the joining electrode (7) within the range of the molten pool (26), At the start of the pause phase (PP), the arc (11) is extinguished and wire feeding is stopped. Wire feeding restarts at the start-up point (TA) after a pause interval (ΔR) during the pause phase (PP). The period between the start time (TA) and the firing time (TZ) immediately following the start time (TA) is determined as the parameter value (PW) of the description parameter (PT). and / or, The approach distance (s) over which the welding wire (8) moves between the start time (TA) and the firing time (TZ) immediately following the start time (TA) ｄ ) is determined as the parameter value (PW) of the descriptive parameter (PT). The arc interval joining method according to feature 6.

8. Wire feeding speed (v ｄ ), and / or The junction current (I) in the arc phase (LP), and / or Startup time (TA), and / or The distance between the welding wire (7a) and the workpiece (6) at the start time (TA), and / or The period between the extinction time (TL) and the activation time (TA), and / or The current-time area in the arc phase (LP) is: The joining parameters of the arc interval joining method are changed to affect the firing time (TZ). The arc interval joining method according to feature 7.

9. To change the distance between the welding wire (7a) and the workpiece (6) at the start time (TA) as a joining parameter for the arc interval joining method to affect the firing time (TZ), the wire feeding speed (v) is changed. ｄ The junction current (I) in the arc phase (LP) and / or the current-time area in the arc phase (LP) are changed. The arc interval joining method according to feature 8.

10. At least one parameter value (PW) of at least one description parameter (PT) is determined by a filter, or by an observer, or by an adaptive system, or by a neural network, from at least one measurement of one or more junction parameters of the arc interval junction method. At least one junction parameter is set to influence the second pause phase (PP2) according to a predetermined control law (R). The arc interval joining method according to any one of claims 6 to 9.

11. A welding apparatus (1) that performs an arc interval joining method, The aforementioned arc interval joining method has a series of stages: an arc phase (LP) including a predetermined arc duration, and a pause phase (PP) that alternates with the arc phase (LP) over time. During the arc phase (LP), a bonding current (I) flows between the bonding electrode (7) and the workpiece (6) to bond the workpiece (6), and during the pause phase (PP), no bonding current (I) flows. The welding apparatus (1) includes a welding torch (4) that forms an arc (11) for introducing energy to the joint (25) on the workpiece (6) in order to form a molten pool (26), The welding apparatus (1) includes a supply unit (12) for supplying the joining electrode (7) to the molten pool (26), The joining electrode (7) is meltable within the region of the molten pool (26) by the energy introduced by the welding torch (4) in order to form a seam (10) in the workpiece (6). The welding apparatus (1) includes a control unit (14) for controlling the welding apparatus (1). In the welding apparatus (1), The control unit (14) is During the arc interval joining method, the first pause phase (PP １ ) First pause duration (TP １ It is configured to determine, The determined first pause duration (TP) １ ) is the predetermined target pause duration (TP ｓｏｌｌ If there is a difference between this and the first pause duration (TP １ ) and target pause duration (TP ｓｏｌｌ By comparing the difference between ) and the first pause stage (PP １ ) followed by a second pause phase (PP) over time. ２ ) Second pause duration (TP ２ ) and a predetermined target pause duration (TP ｓｏｌｌ The configuration is such that at least one bonding parameter of the arc interval bonding method that affects the pause duration of the pause phase (PP) is changed so that the difference between the above and below becomes smaller. A welding apparatus (1) characterized by the following.

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