Welding system, transmission control method, and communication connection method

Abstract

In the feeding control method, the motion precision of the front end position of the wire is high, and the welding condition is optimally controlled on the basis of at least one of the front end position of the wire and the feeding speed. A welding system for periodically feeding a leading end of a welding wire toward a base material with a forward feeding period and a reverse feeding period as one cycle and controlling a welding condition based on at least one of a leading end position and a feeding speed of the welding wire includes a welding control device, a welding power source, a servo motor, and a servo amplifier. The servo amplifier and the welding power source are directly or indirectly connected through digital communication, and the servo amplifier is provided with a unit for generating a forward sending instruction or a reverse sending instruction based on setting information input through digital communication; a means for outputting, to the servomotor, a control signal based on the generated transmission command; and a means for outputting a synchronization signal related to the generated feed command to the welding power supply. The welding power supply has a means for calculating the wire position phase on the basis of the synchronization signal.

Description

Technical Field

[0001] The present invention relates to a welding system, a feeding control method, and a communication connection method. Background Art

[0002] Conventionally, gas shielded arc welding has been used in the manufacture of motor vehicles, steel bars, construction machinery, shipbuilding, and various other industrial types. In this gas shielded arc welding, improvement of welding workability including reduction of spatter is sought. Among the conventional methods effective for reducing spatter, there is a method (hereinafter, also referred to as "feeding control method") in which the forward feeding period and the reverse feeding period of a welding wire (hereinafter, also simply referred to as "wire") are set as one cycle and repeated periodically, and welding is performed while controlling at least one of the welding conditions based on at least one of the tip position of the wire and the feeding speed.

[0003] Patent Document 1 discloses that, in the case of arc welding by periodically repeating the forward feeding and reverse feeding of the tip of a wire as a consumable electrode, for the purpose of suppressing the generation of spatter even when a large current flows through the wire, a consumable electrode type arc welding power source that supplies a welding current to the wire as a consumable electrode has a control unit that changes the welding current according to the periodically changing tip position of the wire when the wire is fed toward the base material along with the periodic switching between the forward feeding period and the reverse feeding period of the tip of the wire. Thus, reduction of spatter can be achieved even in the high current range where welding can be performed with good input heat efficiency.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-49506 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] Patent Document 1 reduces sputtering by controlling the welding current according to the tip position of the wire or the wire feeding speed. However, the tip position of the wire is calculated based on the wire feeding speed. When the update cycle of the command for the wire feeding speed (hereinafter referred to as the "forward / backward feeding command") output to the servo amplifier that controls the servo motor for forward or backward feeding of the wire is slow, the number of updates based on this forward / backward feeding command is limited, and the movement of the tip position of the wire cannot be obtained with good accuracy. Also, sometimes a phase shift occurs between the forward / backward feeding command and the movement of the tip position of the wire, and there are cases where the welding current cannot be controlled at the optimal timing. As a result, there is a possibility that the timing of current control is disrupted, the effect of reducing sputtering cannot be obtained, etc., and the improvement effect of welding workability cannot be obtained. As a reason for the slow command speed of the wire feeding speed, the communication speed can be cited, but in the current structure where the feeding command is transmitted digitally from the control unit in the welding power source to the servo amplifier, updating the wire feeding speed command every about 1 ms (millisecond) becomes the limit. For example, when the frequency (hereinafter referred to as the "wire forward / backward frequency") in one cycle of the forward feeding period and the backward feeding period is set to 100 Hz, if the communication speed is 1 ms, only 10 updates can be performed. It should be noted that in order to obtain the improvement effect of welding workability, it is necessary to update the feeding command at least at a cycle faster than 200 us. In this case, when the wire forward / backward frequency is set to 100 Hz, 50 updates can be performed.

[0009] An object of the present invention is to provide a welding system, a feeding control method, and a communication connection method in which the movement accuracy of the tip position of the wire is high in the feeding control method, and the control of welding conditions based on at least one of the tip position of the wire and the feeding speed can be optimally achieved.

[0010] Solution to the problem

[0011] The present invention is configured as follows.

[0012] (1) A welding system for feeding the tip of a welding wire toward a base material while periodically repeating feeding in a cycle of a forward feeding period and a backward feeding period, and controlling at least one of welding conditions based on at least one of the tip position of the welding wire and the feeding speed,

[0013] The welding system is characterized in that,

[0014] The welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor,

[0015] At least the servo amplifier is directly or indirectly connected to the welding power source by digital communication,

[0016] The servo amplifier has:

[0017] a unit that generates a feed command for forward feed or reverse feed based on set information input through the digital communication;

[0018] a unit that outputs a control signal based on the generated feed command to the servo motor; and

[0019] a unit that outputs a synchronization signal related to the generated feed command to the welding power source,

[0020] The welding power source has a unit that calculates the wire position phase based on the synchronization signal.

[0021] (2) A feed control method, which periodically repeats feeding the tip of the welding wire in a cycle with a forward feed period and a reverse feed period while feeding it toward the base material, and performs welding while controlling at least one of the welding conditions based on at least one of the tip position and the feed speed of the welding wire. Among them,

[0022] in a welding system including at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor, at least the servo amplifier and the welding power source are directly or indirectly connected by digital communication,

[0023] The servo amplifier generates a feed command for forward feed or reverse feed based on set information input through the digital communication,

[0024] The servo amplifier outputs a control signal based on the generated feed command to the servo motor,

[0025] The servo amplifier outputs a synchronization signal related to the generated feed command to the welding power source,

[0026] The welding power source calculates the wire position phase based on the synchronization signal.

[0027] (3) A communication connection method for communicating between devices constituting a welding system. The welding system feeds the tip of the welding wire in a cycle with a forward feed period and a reverse feed period while feeding it toward the base material, and controls at least one of the welding conditions based on at least one of the tip position and the feed speed of the welding wire. Among them,

[0028] The welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor,

[0029] at least the servo amplifier and the welding power source are directly or indirectly connected by digital communication,

[0030] The servo amplifier generates a forward feed or reverse feed command based on setting information input digitally from a device other than the servo amplifier among the devices constituting the welding system,

[0031] The servo amplifier outputs a control signal based on the generated feed command to the servo motor.

[0032] The servo amplifier outputs a synchronization signal related to the generated feed command to the welding power source.

[0033] The welding power source calculates the wire position phase based on the synchronization signal.

[0034] Advantages of the Invention

[0035] According to the present invention, in the feed control method, the operation accuracy of the tip position of the wire is high, and control for obtaining optimal welding conditions can be performed based on at least one of the tip position of the wire and the feed speed, and good welding workability can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram showing a structural example of the welding system of the present embodiment.

[0037] Figure 2 is a block diagram showing a schematic configuration of the control of the welding power source, the welding control device, and the servo amplifier in the present embodiment.

[0038] Figure 3 is a chart illustrating the relationship between the current setting signal, the speed phase, the position phase, and the synchronization signal.

[0039] Figure 4 is a flowchart illustrating task processing in gas shielded arc welding according to the welding sequence. DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, embodiments of a welding system, a feed control method, and a communication connection method for gas shielded arc welding of the present invention will be described in detail based on the drawings.

[0041] It should be noted that this embodiment is an example of the case where a welding robot is used, and the welding control method of the present invention is not limited to the structure of this embodiment. For example, an automatic welding device using a carriage instead of the welding robot main body may be applied, or a movable small welding robot may be applied.

[0042] In the present embodiment, a gas metal arc welding (hereinafter, also referred to as "GMAW") method that uses a welding wire as a consumable electrode in gas shielded arc welding will be described. However, the welding system of the present invention can be similarly applied to an additive manufacturing system that uses gas metal arc welding. It should be noted that the case of using a non-consumable electrode such as TIG with a filler wire also falls within the scope of the present invention.

[0043] Figure 1 FIG. is a schematic diagram showing a structural example of the welding system according to the present embodiment. The welding system 50 includes a welding robot 110, a welding control device 120, a welding power source 140, a controller 150, a servo amplifier 160, a servo motor 170, a push motor 180, and a wire buffer 190. The push motor 180 feeds the welding wire 100.

[0044] The welding power source 140 is connected to the welding robot 110 via a positive power cable (not shown) so as to be able to energize the welding wire 100 as a consumable electrode, and is connected to the workpiece (hereinafter, also referred to as "base material") 200 via a negative power cable (not shown). This connection is for welding in reverse polarity. In the case of welding in positive polarity, the welding power source 140 just needs to reverse the polarity.

[0045] In addition, the welding power source 140 and the push motor 180 are connected by a signal line, and the feeding speed of the welding wire can be controlled. In the feeding control of the present embodiment, the push motor 180 only rotates in the forward direction, and the servo motor 170 described later switches between the forward and reverse directions.

[0046] The welding robot 110 includes a torch 111 as an end effector. The torch 111 has an energizing mechanism for energizing the welding wire 100, that is, a welding tip. The welding wire 100 generates an arc from the tip by being energized through the welding tip, and uses its heat to weld the workpiece 200 as the object of welding. It should be noted that the welding tip is sometimes generally also referred to as a contact tip.

[0047] The torch 111 includes a shielding gas nozzle that serves as a mechanism for ejecting a shielding gas. The shielding gas is not particularly limited, but in terms of the control characteristics used in the present embodiment, it may be set to a gas composition that adopts a droplet transfer method. Specifically, it is preferably at least one gas among carbon dioxide gas, nitrogen gas, hydrogen gas, and oxygen gas having a relatively high potential gradient. In addition, from the viewpoint of versatility, in the case of a mixed gas with argon (hereinafter, also referred to as "Ar gas"), a system in which carbon dioxide gas is mixed with at least 10% by volume or more is more preferable, a system in which carbon dioxide gas is mixed with 90% by volume or more is further preferable, and it is further more preferable to use carbon dioxide gas alone. It should be noted that the shielding gas is supplied from a shielding gas supply device (not shown).

[0048] The servo motor 170 is disposed near the torch 111. The servo amplifier 160 connected to the servo motor 170 controls the servo motor 170. In the present embodiment, the torch 111 is configured to be independent of the servo motor 170, but the torch may also be configured to include the servo motor 170 therein. The servo motor 170 switches between the forward and reverse rotation directions based on the forward and reverse feed commands and performs feed control. In addition, the servo amplifier 160 is capable of performing high-speed arithmetic processing and has a forward and reverse feed command generation unit 161 as described later.

[0049] A wire buffer 190 is disposed between the push motor 180 and the servo motor 170. The push motor 180 feeds the wire only in the forward rotation direction, and the servo motor 170 feeds the wire in the forward and reverse rotation directions, so there are cases where the feed directions are different between the push motor 180 and the servo motor 170. Therefore, a situation is generated in which a large load is easily applied to the wire in the feed path. The wire buffer 190 is provided to suppress buckling of the wire, etc., so that feed control can be appropriately performed even in such a feeding situation.

[0050] The welding wire 100 used in the present embodiment is not particularly limited. For example, either a solid wire not including a flux or a flux-cored wire including a flux may be used. In addition, the material of the welding wire 100 is not limited. For example, the material may be mild steel, stainless steel, aluminum, titanium, or a plating such as Cu may be present on the wire surface. The diameter of the welding wire 100 is not particularly limited. In the case of the present embodiment, it is preferable that the upper limit of the diameter is set to 1.6 mm and the lower limit is set to 0.8 mm.

[0051] In addition, in the present embodiment, the specific structure of the workpiece 200 is not particularly limited, and welding conditions such as the joint shape, welding posture, and groove shape are also not particularly limited. The welding control device 120 mainly controls the operation of the welding robot 110. Thus, the welding control device 120 may also be referred to as a robot controller. The welding control device 120 stores teaching data that pre-determines the operation mode, welding start position, welding end position, welding conditions, oscillation operation, etc. of the welding robot 110, and instructs the welding robot 110 with these teaching data to control the operation of the welding robot 110. In addition, the welding control device 120 gives welding conditions such as welding current, welding voltage, and feed speed during the welding operation to the welding power source 140 according to the teaching data.

[0052] It should be noted that, as Figure 1 shown, the welding system 50 of the present embodiment is configured such that the welding control device 120 is independent of the welding power source 140, but it may also be configured such that the welding control device 120 is provided in the welding power source 140.

[0053] The controller 150 is connected to the welding control device 120 and is used to create or display programs for operating the welding robot 110, input teaching data, etc. The information input by the user to the controller 150 is given to the welding control device 120. In addition, the controller 150 may also have the function of manually operating the welding robot 110. The connection between the controller 150 and the welding control device 120 is not particularly limited to the type of wired or wireless.

[0054] The welding power source 140 supplies power to the welding wire 100 and the workpiece 200 according to an instruction from the welding control device 120, thereby generating an electric arc between the welding wire 100 and the workpiece 200. In addition, the welding power source 140 outputs a control signal for driving the motor 180 according to an instruction from the welding control device 120.

[0055] Next, refer to Figure 2 The functional structure of the welding system 50 of this embodiment will be described in detail. Figure 2 It is a block diagram showing the schematic structure of the control of the welding power source 140, the welding control device 120, and the servo amplifier 160 in this embodiment.

[0056] The welding power source 140 and the welding control device 120 are connected by digital communication, and the welding control device 120 and the servo amplifier 160 are connected by digital communication. That is, they are linearly connected in the order of the servo amplifier 160, the welding control device 120, and the welding power source 140 that are connected by digital communication. This can be interpreted as a state where the servo amplifier 160 and the welding power source 140 are indirectly connected by digital communication. It should be noted that they can also be linearly connected in the order of the servo amplifier 160, the welding power source 140, and the welding control device 120. This can be interpreted as a state where the servo amplifier 160 and the welding power source 140 are directly connected by digital communication.

[0057] It should be noted that in this embodiment, communication between the welding power source 140 and the welding control device 120 is performed using CAN (Controller Area Network), which is one of the industrial field networks, and communication between the welding control device 120 and the servo amplifier 160 is performed using EtherCAT (Ethernet for Control Automation Technology) (registered trademark), which is one of the industrial field networks, but it is not limited to these.

[0058] (Functional Structure of Welding Power Source)

[0059] The control system unit 141 of the welding power source 140 is executed, for example, by the execution of a program by the welding control device 120 or a computer (not shown). The current setting unit 36 is included in the control system unit 141 of the welding power source 140. The current setting unit 36 in the present embodiment has a function of setting various current values that define the welding current flowing through the welding wire 100. The current setting unit 36 includes a target current setting unit 36A, a wire tip position conversion unit 36B, and a voltage setting unit 36C. The target current setting unit 36A has a function of setting the start time and end time of each of the peak period Dap, decay period Ddwn, base period Db, and rise period Dup related to current control. The wire tip position conversion unit 36B has a function of obtaining information on the tip position of the welding wire 100.

[0060] It should be noted that various condition settings for each of the peak period Dap, decay period Ddwn, base period Db, and rise period Dup related to the current non-suppression period TIP (the sum of the Dup and Dap periods in the present embodiment) and the current suppression period TIB (the sum of the Ddwn and Db periods in the present embodiment) can be determined by the waveform control table linear operation unit 37 based on a pre-prepared waveform control table. It should be noted that the various condition settings mentioned here mean condition settings such as current values, times, or phases in the present embodiment.

[0061] The welding current shows a pulse waveform of the welding current that alternately repeats the current non-suppression period TIP and the current suppression period TIB based on the phase related to the wire tip position (hereinafter, referred to as "wire position phase" or "position phase"). It should be noted that in the present embodiment, based on the wire position phase of 0 to 360° (0 to 2π) where the wire tip position closest to the nozzle side is set to 0° and the position closest to the base material side is set to 180°, the timing of the peak period Dap, decay period Ddwn, base period Db, and rise period Dup is controlled.

[0062] The control system unit 141 sets the set current value Iap (hereinafter, also referred to as "peak current Iap") of the peak period Dap in the current non-suppression period TIP and the set current value Ib (hereinafter, also referred to as "base current Ib") of the base period Db in the current suppression period TIB calculated by the waveform control table linear operation unit 37 for the current setting unit 36 based on the set value of the average feed speed Favg in the stored welding condition information. It should be noted that, although it is just an example, the value obtained by adding the peak current command value Ip from the waveform control table and the operation amount Mn can also be used as the peak current Iap. In this case, Iap = Ip + Mn. The operation amount Mn is calculated based on the voltage set value Vap and the value Vo of the voltage detection signal.

[0063] In the case of this embodiment, the welding current is basically controlled by two values, namely the peak current Iap and the base current Ib. Therefore, the start time of the base period Db represents the time when the base current Ib starts, that is, the base current start time. In addition, the time when the current suppression period Db ends represents the time when the base current Ib ends, that is, the base current end time. The start time of the base period Db, the end time of the base period Db, the period (time) of the down period Ddwn, and the period (time) of the down period Ddwn are calculated in the waveform control table linear operation unit 37. The start time of the peak period Dap can also be expressed as the peak current start time, and the end time of the peak period Dap can also be expressed as the peak current end time.

[0064] It should be noted that the above various start times, end times, etc. are described based on time. However, it is also possible to perform processing by converting the value from the wire position phase to time or cycle cyc based on the value of the wire position phase. That is, the values of the wire position phase, time, and cycle cyc can be mutually converted, so control can also be performed based on any value.

[0065] In addition, based on the phase synchronization signal and the phase delay correction amount signal from the servo amplifier 160, the wire tip position conversion unit 36B determines the wire tip position. It should be noted that in this embodiment, the wire tip position can be expressed as an angle (0 to 2π) as the wire position phase as described above.

[0066] The phase delay correction amount signal is output from the phase delay correction unit 38. The phase delay correction unit 38 has a database (not shown). In this database, for various welding conditions, data obtained by previously calculating the difference between the periodic setting information and the actual forward and reverse feed operation signals of the servo motor 170 is stored. For example, in the case where the welding condition is the wire forward and reverse frequency, based on the value of the used wire forward and reverse frequency, the phase delay correction amount is determined based on the above database and output as the phase delay correction amount signal from the phase delay correction unit 38.

[0067] The power main circuit of the welding power source 140 is composed of a three-phase AC power source (hereinafter, also referred to as "AC power source") 1, a primary side rectifier 2, a smoothing capacitor 3, a switching element 4, a transformer 5, a secondary side rectifier 6, and a reactor 7.

[0068] The alternating current power input from the alternating current power supply 1 is full-wave rectified by the primary rectifier 2, and then smoothed by the smoothing capacitor 3 to be converted into direct current power. Next, after the direct current power is converted into high-frequency alternating current power through inverter control by the switching element 4, it is converted into secondary-side power through the transformer 5. The alternating current output of the transformer 5 is full-wave rectified by the secondary rectifier 6, and then smoothed by the reactor 7. The output current of the reactor 7 is given to the welding tip as the output from the power supply main circuit, and electricity is supplied to the welding wire 100 as a consumable electrode.

[0069] The welding wire 100 is fed by the feeding motor 180, and an arc is generated between the welding wire 100 and the base material 200. The forward feeding period during which the front end of the welding wire 100 moves toward the base material 200 is denoted as the forward feeding period TP. The reverse feeding period during which the front end of the welding wire 100 moves in the direction opposite to the direction where the base material 200 is located is denoted as the reverse feeding period TN. In the case of this embodiment, the feeding motor takes the forward feeding period TP and the reverse feeding period TN together as one cycle, and feeds the welding wire 100 periodically. It should be noted that the front end of the welding wire generally refers to the front end of the wire regardless of the existence of the molten droplet hanging at the front end of the wire. That is, the wire melted by the arc is regarded as immediately transferred to the base material 200.

[0070] The feeding of the welding wire 100 by the feeding motor 180 is controlled based on the control signal of the pushing control unit 39. It should be noted that the average value of the feeding speed is approximately the same as the melting speed. In the case of this embodiment, the feeding of the welding wire 100 by the feeding motor 180 is also controlled by the welding power supply 140.

[0071] In addition, the pushing control unit 39 performs control according to the state of the wire buffer 190. In this embodiment, the wire buffer 190 is configured such that a large load is not applied to the wire in the feeding path between the feeding motor 180 and the servo motor 170. A slack portion of the wire (a clearance portion for avoiding when the wire is slack due to the influence of feeding between the motors) is provided in the wire buffer 190. Using an absolute encoder as a sensor built into the wire buffer 190, the buffer amount of the wire is detected as a rotation angle. The detected value is converted into an analog signal by the serial analog conversion unit 191, and the electrical angle is calculated by the electrical angle calculation unit. The calculated electrical angle is input to the A / D input unit 40 of the welding power supply.

[0072] A difference signal obtained by taking the difference between the electrical angle from the A / D input unit 40 and the reference value of the electrical angle preset in the electrical angle adjustment unit 41 is input to the pushing control unit 39. Based on this difference signal, the pushing control unit 39 controls the pushing motor 180 so as to achieve an appropriate wire buffer amount, thereby performing interference control that does not impose a large load on the feeding system. It should be noted that in this embodiment, the foregoing interference control is performed, but it should not be limited thereto. In addition, in this embodiment, an absolute encoder built into the wire buffer 190 is used, but it should not be limited thereto. For example, a rotation angle sensor may also be used, and in this case, the serial analog conversion unit 191 may not be provided.

[0073] A voltage setting signal Vap, which is a target value of the voltage applied between the welding tip and the base material 200, is given from the voltage setting unit 36C to the current setting unit 36.

[0074] On the other hand, the voltage detection signal Vo is the measured value. In this embodiment, the voltage detection signal Vo passes through a low-pass filter LPF, passes through the detachment detection unit 33 described later, and is input to the current setting unit 36 together with the detachment detection signal DTR described later. It should be noted that the following structure may also be adopted: a voltage comparison unit is provided to amplify the difference between the voltage setting signal Vap and the voltage detection signal Vo and output it to the current setting unit 36 as a voltage error amplification signal.

[0075] The current setting unit 36 controls the welding current during the peak period Dap so that the length of the arc (hereinafter, also referred to as "arc length") becomes constant. The current setting unit 36 determines and sets at least the peak period, the rising period, the base period, and the rising period based on the voltage setting signal Vap and the voltage detection signal Vo. It should be noted that the value of the peak current Ip and the value of the base current Ib may also be set again. The current setting signal CCset corresponding to the set period or value is output to the current error amplification unit (PWM) 34.

[0076] The current error amplification unit 34 amplifies the difference between the current setting signal CCset given as the target value and the current detection signal Io detected by the current detection unit 31, and outputs it to the inverter drive unit 30 as a current error amplification signal Ed. The inverter drive unit 30 corrects the drive signal Ec of the switching element 4 using the current error amplification signal Ed.

[0077] The detachment detection signal DTR, which is a signal indicating the detection of the detachment of the molten droplet from the tip of the welding wire 100, is also input to the current setting unit 36. The detachment detection signal DTR is output from the detachment detection unit 33. The detachment detection unit 33 monitors the change in the voltage detection signal Vo output from the voltage detection unit 32, and detects the detachment of the molten droplet from the welding wire 100 based on this change. It should be noted that the detachment detection unit 33 is an example of a detection unit.

[0078] The detachment detection unit 33, for example, compares the value obtained by differentiating or second-differentiating the voltage detection signal Vo that has passed through the LPF with a specified threshold value for detection, thereby detecting the detachment of the molten droplet. The threshold value for detection is stored in a storage unit (not shown) in advance. It should be noted that the detachment detection unit 33 can also generate the detachment detection signal DTR based on the change in the resistance value calculated from the voltage detection signal Vo and the current detection signal Io as measured values.

[0079] The waveform control table linear operation unit 37 is given the average feeding speed Favg of the supplied welding wire 100. The average feeding speed Favg is stored in the feeding setting data unit 35 in advance. It should be noted that in this embodiment, the feeding setting data unit 35 is located within the welding power source 140, but various information related to the feeding setting can also be stored in the welding control device 120 in advance, and the various information can be output from the welding control device 120 to the welding power source 140.

[0080] Based on the given average feeding speed Favg, the waveform control table linear operation unit 37 determines values such as the peak current Ip, the base current Ib, the start time of the base current Ib, and the end time of the base current Ib, and outputs them to the current setting unit 36. It should be noted that as described above, the values of the wire position phase, time, and cycle cyc can be mutually transformed, so the set value of the base start phase, etc. can also be converted into values of time or cycle cyc, and the converted values can be output to the current setting unit 36.

[0081] In this embodiment, the average feeding speed Favg is input to the waveform control table linear operation unit 37, but it can also be that a value associated with the average feeding speed Favg is set as the set value and input to the waveform control table linear operation unit 37, and the waveform control table linear operation unit 37 replaces the set value with the average feeding speed Favg and uses it. For example, when a database of the average feeding speed Favg and the average current value that can perform optimal welding with respect to the average feeding speed Favg is stored in a storage unit (not shown), the average current value can also be used as the set value, and the set value can be replaced with the average feeding speed Favg and used.

[0082] The feed setting data unit 35 may store setting values such as the wire amplitude Wf, the wire forward / backward frequency Sf, and the wire forward / backward period Tf, in addition to the average feed speed Favg. It should be noted that the wire amplitude Wf, the wire forward / backward frequency Sf, and the wire forward / backward period Tf may also be determined based on the input average feed speed Favg. Additionally, the feed setting data unit 35 may store setting values other than these as feed setting data.

[0083] In the present embodiment, the period during which the feed speed is greater than the average feed speed Favg is set as the forward feed period, and the period during which the feed speed is less than the average feed speed Favg is set as the reverse feed period, resulting in a feed (hereinafter, abbreviated as "amplitude feed") in which the forward feed period and the reverse feed period appear alternately. It should be noted that the period during which the feed speed is less than the average feed speed Favg means less than the average feed speed Favg, including a negative feed speed, i.e., the speed at which the front end of the wire moves in the direction opposite to the position of the base material 200. The wire amplitude Wf gives the change amplitude relative to the average feed speed Favg, and the wire forward / backward period Tf gives the time for the change of the wire amplitude as a repetition unit. The wire forward / backward frequency Sf is the reciprocal of the wire forward / backward period Tf.

[0084] The average feed speed Favg, the wire amplitude Wf, the wire forward / backward frequency Sf, and the wire forward / backward period Tf stored in the feed setting data unit 35 are input from the digital communication unit 42 to the digital communication unit 122 of the welding control device 120. In the present embodiment, the communication of these feed setting data is performed using CAN communication.

[0085] The welding sequence unit 43 processes each task in the order of idling, gas flow, arc start, welding, and anti-sticking based on the teaching data. In the "welding" task among these tasks, the control mainly based on the current setting unit 36 described above is performed. It should be noted that Figure 2 For convenience, the welding condition information possessed by the welding control device 120 is also shown surrounded by a dotted line in the welding power source 140.

[0086] (Functional Structure of Welding Control Device)

[0087] To the digital communication unit 122 of the welding control device 120, feed setting data such as the average feed speed Favg, the wire amplitude Wf, the wire forward / backward frequency Sf, and the wire forward / backward period Tf are input from the feed setting data unit 35 of the welding power source 140 through CAN communication as described above. The welding control device 120 has a digital communication unit 123 for outputting these feed setting data to the digital communication unit 162 of the servo amplifier 160. In the present embodiment, the digital communication unit 123 of the welding control device 120 and the digital communication unit 162 of the servo amplifier 160 are connected using EtherCAT (registered trademark) communication.

[0088] (Functional Structure of Servo Amplifier)

[0089] To the digital communication unit 162 of the servo amplifier 160, the feed setting data such as the average feed speed Favg, wire amplitude Wf, wire forward / backward frequency Sf, and wire forward / backward period Tf are input through EtherCAT (registered trademark) communication. Based on the setting information input through digital communication, that is, the feed setting data, the forward / backward feed command generation unit 161 of the servo amplifier 160 generates a forward feed or backward feed command. The forward / backward feed command generation unit 161 calculates the amplitude feed speed Ff from the wire amplitude Wf and the wire forward / backward period Tf, and based on the amplitude feed speed Ff and the average feed speed Favg, outputs a feed speed command signal Fw to the servo motor 170.

[0090] In the case of this embodiment, the feed speed command signal Fw is represented by the following formula.

[0091] Fw = Ff + Favg ··· Formula (A)

[0092] In addition, the forward / backward feed command generation unit 161 can also detect at which wire position phase of the amplitude feed the detachment has occurred based on the detachment detection signal DTR given by the detachment detection unit 33. However, the feed speed command signal Fw represented by Formula (A) is limited to the case where the detachment of the droplet from the tip of the welding wire 100 is detected within the assumed period. In the case where the detachment of the droplet is not detected within the assumed period, the forward / backward feed command generation unit 161 can also switch the feed speed command signal Fw to feed control based on a constant speed. For example, the forward / backward feed command generation unit 161 switches the feed speed command signal Fw to feed based on the average feed speed Favg. The switching from the feed based on the average feed speed Favg to the feed control represented by Formula (A) is determined according to the timing when the detachment of the droplet is detected.

[0093] The servo amplifier 160 performs inverter control of the servo motor 170 based on the feed speed command signal Fw. In addition, the synchronization signal generation unit 163 of the servo amplifier 160 outputs a phase synchronization signal to the welding power source 140. This phase synchronization signal is generated based on the feed speed command signal Fw.

[0094] It should be noted that the welding power source 140 and the synchronization signal generation unit 163 of the servo amplifier 160 can be connected at least by using analog input / output. In this case, the synchronization signal is input from the servo amplifier 160 to the welding power source 140 by means of analog input / output. The feed setting data such as the average feed speed Favg, wire amplitude Wf, wire forward and reverse frequency Sf, and wire forward and reverse period Tf are transmitted by digital communication. On the other hand, the synchronization signal is transmitted by analog communication, so that digital communication and analog communication can be efficiently distinguished and used according to the application.

[0095] Figure 3 It is a chart showing the relationship between the current setting signal CCset, speed phase, position phase, and synchronization signal. It should be noted that in the speed phase of the feed speed, the wavy line indicated by the dotted line represents the feed speed indicated by the feed speed command signal Fw. The wavy line indicated by the solid line in the speed phase of the feed speed represents the actual feed speed Fc_com.

[0096] In the present embodiment, the phase synchronization signal becomes at least one of the synchronization signal of the wire position phase and the synchronization signal of the speed phase of the feed speed (hereinafter, also simply referred to as "speed phase"). As Figure 3 shown, the synchronization signal of the speed phase becomes a synchronization signal that is turned on during the forward feed period (position of 0 to π) and turned off during the reverse feed period (position of π to 2π). On the other hand, the synchronization signal of the position phase becomes a synchronization signal that is turned on during the period when the front end of the wire is closer to the base material 200 side than the center position of the wire amplitude wf (position of wave height Lm / 2) when the wire is fed forward and backward, and turned off during the period when it is closer to the nozzle side than the center position of the wire amplitude. It should be noted that in the present embodiment, the wave height Lm is the difference (mm) between the position where the front end of the wire is closest to the nozzle side and the position where the front end of the wire is closest to the base material side. When the unit of the wire amplitude wf as a set value is set in "mm", the wave height Lm is the same as the wire amplitude wf.

[0097] Based on the phase synchronization signal and the aforementioned phase delay correction amount, the wire front end position conversion unit 36B in the welding power source 140 determines the wire position phase of the welding wire 100. The current setting unit 36 sets various current values that define the welding current flowing through the welding wire 100 based on the determined wire position phase. That is, by determining the wire position phase based on the aforementioned database and synchronization signal, the control of the welding conditions is performed. It should be noted that in the present embodiment, the control of the welding conditions becomes the timing correction of the welding current waveform control. Here, in the present embodiment, the phase delay correction amount is relative to the Figure 3The Deg - adj shown in determines the wire position phase based on the phase synchronization signal of the phase corrected by the Deg - adj amount.

[0098] It should be noted that the control of the welding conditions can also be performed without setting a database in the phase delay correction unit 38. To achieve this, the phase delay correction amount is calculated by reading the operation cycle of the servo motor 170 using an encoder (not shown). That is, the servo amplifier 160 has an encoder as a unit that takes the operation signal of the servo motor 170, such as the phase signal of the forward and reverse feeding operations, as the input setting information, and calculates the difference, such as the phase shift, between the feed command generated by the servo amplifier 160 and the operation signal of the servo motor 170. The wire position phase can also be determined based on the said difference and the synchronization signal, thereby controlling the welding conditions in the welding power source 140. It should be noted that the control of the welding conditions can be set as the timing correction of the waveform control of the welding current.

[0099] Figure 4 It is a flowchart exemplifying the task processing in gas - shielded arc welding according to the welding sequence.

[0100] First, the feed setting data is pre - stored in the feed setting data unit 35 of the welding power source 140. The feed setting data includes the average feed speed Favg, the wire amplitude Wf, the wire forward - reverse frequency Sf, and the wire forward - reverse period Tf, etc.

[0101] The welding power source 140 sends the feed setting data to the welding control device 120 (S1). This sending can be performed using CAN communication or EtherCAT (registered trademark) communication.

[0102] The welding control device 120 sends the feed setting data to the servo amplifier 160 (S2). This sending can be performed using EtherCAT (registered trademark) communication.

[0103] The forward - reverse feed command generation unit 161 of the servo amplifier 160 calculates the feed speed command signal Fw that forms the basis for driving and controlling the servo motor 170 based on the obtained feed setting data, that is, the average feed speed Favg, the wire amplitude Wf, the wire forward - reverse frequency Sf, and the wire forward - reverse period Tf (S3).

[0104] Note that, in the present embodiment, the welding power source 140 and the welding control device 120 are connected by digital communication, and the welding control device 120 and the servo amplifier 160 are connected by digital communication. Therefore, the processes of the above steps S1 and S2 are performed. However, it is not limited thereto, and the processes corresponding to the network connection method of each device may be performed. For example, a network connection method in which the servo amplifier 160 and the welding power source 140 are connected by digital communication, and the welding power source 140 and the welding control device 120 are connected by digital communication is also considered. In this case, the feed setting data of the average feed speed Favg, the wire amplitude Wf, the wire forward / backward frequency Sf, and the wire forward / backward period Tf can be stored in either the welding power source 140 or the welding control device 120. When the feed setting data is stored in the welding power source 140, the feed setting data is transmitted from the welding power source 140 to the servo amplifier 160 by EtherCAT (registered trademark) communication. When the feed setting data is stored in the welding control device 120, for example, the feed setting data is transmitted from the welding control device 120 to the welding power source 140 by CAN communication, and the feed setting data is transmitted from the welding power source 140 to the servo amplifier 160 by EtherCAT (registered trademark) communication.

[0105] In step S4, the process of the welding sequence unit 43 is started. Regarding the tasks of "idle rotation", "gas flow", and "arc start", they are general tasks in gas shielded arc welding, so the detailed description is omitted.

[0106] In step S5, after a predetermined time has elapsed since the task of the welding sequence unit 43 becomes "welding", the servo motor 170 is controlled based on the feed speed command signal Fw. In addition, the synchronization signal generation unit 163 generates at least one of the synchronization signals of the speed phase and the position phase described above based on the feed speed command signal Fw, and outputs the generated synchronization signal to the welding power source 140.

[0107] In step S6, the welding power source 140 corrects the phase shift of the phase synchronization signal based on the phase delay correction amount calculated by the phase delay correction unit 38 of the welding power source 140. The welding power source 140 inputs the corrected phase synchronization signal to the wire tip position conversion unit 36B, and calculates the wire position phase of the real-time welding wire 100. Note that it is more preferable to correct the phase shift from the viewpoint of the operation accuracy of the tip position of the wire. However, the welding power source 140 may also directly input the phase synchronization signal to the wire tip position conversion unit 36B without correcting it.

[0108] Based on the real-time wire position phase of the welding wire 100 calculated in step S6, control is performed on the welding current using the welding power source 140 (step S7). It should be noted that, in the present embodiment, waveform control of the welding current is performed as control of the welding conditions. However, the control of the welding conditions in step S7 is not limited to waveform control of the welding current. For example, waveform control of the arc voltage or control of the welding speed in the welding conditions may also be performed. For example, waveform control of the welding current and waveform control of the arc voltage may be performed to control multiple welding conditions.

[0109] In S8, during the period when the task of the welding sequence unit 43 is "welding in progress", the processing of steps S5 to S7 is continued. When the task of "welding in progress" is completed, "anti-sticking" control is performed and welding is completed. It should be noted that, regarding the task of "anti-sticking", it is a task generally performed in gas shielded arc welding, so detailed description is omitted.

[0110] Through the above steps S1 to S8, smooth data transmission based on digital communication can be performed. And by making the servo amplifier 160 capable of high-speed arithmetic processing generate a signal for forward and reverse feed commands (feed speed command signal Fw), the movement of the tip of the wire can be accurately grasped.

[0111] By outputting a synchronization signal from the servo amplifier 160 to the welding power source 140 and controlling welding conditions such as the welding current based on the synchronization signal, higher-level control can be performed.

[0112] Therefore, in the welding system 50 of the present invention, in the feed control method, the movement accuracy of the tip position of the wire is relatively high, and control such as welding current waveform control based on at least one of the tip position of the wire and the feed speed can be optimally achieved.

[0113] The present invention is not limited to the above-described embodiments. Combining the structures of the embodiments, and making changes and applications by those skilled in the art based on the description in the specification and well-known techniques are also contemplated by the present invention and are included in the scope of protection claimed.

[0114] As described above, the following matters are disclosed in this specification.

[0115] (1) A welding system for feeding the tip of a welding wire toward a base material while periodically repeating feeding in a forward feeding period and a reverse feeding period as one cycle, and controlling at least one of welding conditions based on at least one of the tip position of the welding wire and the feeding speed,

[0116] The welding system is characterized in that,

[0117] The welding system at least includes a welding control device, a welding power source, a servo motor, and a servo amplifier that controls the servo motor.

[0118] At least the servo amplifier is directly or indirectly connected to the welding power source by digital communication.

[0119] The servo amplifier has:

[0120] a unit that generates a feed command for forward feed or reverse feed based on setting information input through the digital communication;

[0121] a unit that outputs a control signal based on the generated feed command to the servo motor; and

[0122] a unit that outputs a synchronization signal related to the generated feed command to the welding power source.

[0123] The welding power source has a unit that calculates the wire position phase based on the synchronization signal.

[0124] According to this welding system, in the feed control method, the movement accuracy of the front end position of the wire is high, and it is possible to optimally implement the control of the welding conditions based on at least one of the front end position of the wire and the feed speed.

[0125] (2) The welding system according to (1), characterized in that

[0126] the synchronization signal is a signal based on at least one of the wire position phase and the speed phase of the feed speed.

[0127] According to this welding system, it is possible to achieve synchronization between the servo motor and the welding power source based on the wire position phase or the speed phase of the feed speed.

[0128] (3) The welding system according to (1) or (2), characterized in that

[0129] the servo amplifier has a unit that inputs the setting information and the operation signal of the servo motor and calculates the difference between the generated feed command and the operation signal of the servo motor.

[0130] The welding power source has a unit that controls the welding conditions based on the difference and the synchronization signal.

[0131] According to this welding system, since the servo amplifier can perform high-speed arithmetic processing, it is possible to accurately detect the deviation between the feed command based on the setting information and the actual operation of the servo motor, and to correct the deviation with high precision.

[0132] (4)The welding system according to any one of (1) to (3), characterized in that

[0133] The welding power source has the following units: a database having data obtained by calculating the difference between the set information and the operation signal of the servo motor in advance, and controlling the welding conditions based on the database and the synchronization signal.

[0134] According to this welding system, it is possible to properly synchronize welding conditions such as the timing of waveform control of the welding current controlled by the welding power source with the servo motor that controls the feeding of the wire.

[0135] (5)The welding system according to any one of (1) to (4), characterized in that

[0136] The set information includes set values of at least one of an average feeding speed, a wire amplitude, a wire forward and reverse frequency, and a wire forward and reverse period.

[0137] According to this welding system, the servo motor can generate a feeding command for forward feeding or reverse feeding based on the above set values.

[0138] (6)The welding system according to any one of (1) to (5), characterized in that

[0139] The welding power source and the servo amplifier are connected at least by analog input and output,

[0140] The synchronization signal is input to the welding power source from the servo amplifier through the analog input and output at least.

[0141] According to this welding system, the set information is transmitted by digital communication, and on the other hand, the synchronization signal is transmitted by analog communication, so that digital communication and analog communication can be efficiently distinguished and used according to the purpose.

[0142] (7)The welding system according to any one of (1) to (6), characterized in that

[0143] The welding system includes a wire buffer device and a pushing motor,

[0144] The wire buffer device has a sensor for detecting the buffer amount of the wire,

[0145] The welding power source has a unit for controlling the pushing motor based on the input buffer amount.

[0146] According to this welding system, it is possible not to apply a large load to the wire in the feeding path between the pushing motor and the servo motor.

[0147] (8) A wire feeding control method, which feeds the front end of the welding wire while periodically repeating the feeding with the forward feeding period and the reverse feeding period set as one cycle toward the base material, and performs welding while controlling at least one of the welding conditions based on at least one of the front end position of the welding wire and the feeding speed, wherein,

[0148] In a welding system including at least a welding control device, a welding power source, a servo motor, and a servo amplifier for controlling the servo motor, at least the servo amplifier and the welding power source are directly or indirectly connected by digital communication.

[0149] The servo amplifier generates a forward feeding or reverse feeding command based on the setting information input through the digital communication.

[0150] The servo amplifier outputs a control signal based on the generated feeding command to the servo motor.

[0151] The servo amplifier outputs a synchronization signal related to the generated feeding command to the welding power source.

[0152] The welding power source calculates the wire position phase based on the synchronization signal.

[0153] According to this wire feeding control method, the movement accuracy of the front end position of the wire in the wire feeding control method is high, and the control of the welding conditions based on at least one of the front end position of the wire and the feeding speed can be optimally achieved.

[0154] (9) A communication connection method for communicating between devices constituting a welding system, the welding system feeding the front end of the welding wire while periodically repeating the feeding with the forward feeding period and the reverse feeding period set as one cycle toward the base material, and controlling at least one of the welding conditions based on at least one of the front end position of the welding wire and the feeding speed, wherein,

[0155] The welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier for controlling the servo motor.

[0156] At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication.

[0157] The servo amplifier generates a forward feeding or reverse feeding command based on the setting information input through digital communication from a device other than the servo amplifier among the devices constituting the welding system.

[0158] The servo amplifier outputs a control signal based on the generated feeding command to the servo motor.

[0159] The servo amplifier outputs the synchronization signal related to the feed command generated to the welding power source.

[0160] The welding power source calculates the wire position phase based on the synchronization signal.

[0161] According to this communication connection method, in the feed control method, the operation accuracy of the tip position of the wire is high, and the control of the welding conditions based on at least one of the tip position of the wire and the feed speed can be optimally achieved.

[0162] (10)The communication connection method according to (9), characterized in that

[0163] The digital communication is digital communication connected using an industrial field network.

[0164] It is linearly connected in the order of the servo amplifier, the welding control device, the welding power source, or in the order of the servo amplifier, the welding power source, the welding control device.

[0165] According to this communication connection method, it is possible to smoothly transmit setting information between the devices constituting the welding system by making use of the industrial field network.

[0166] As described above, various embodiments have been described, but the present invention is of course not limited to this example. As long as a person skilled in the art, various modification examples or correction examples can clearly be conceived within the scope described in the patent technical solution, and they are of course also understood to belong to the technical scope of the present invention. In addition, within the scope not departing from the gist of the invention, the constituent elements in the above-described embodiments can be arbitrarily combined.

[0167] It should be noted that this application is based on a Japanese patent application (Japanese Patent Application No. 2022-192369) filed on November 30, 2022, the content of which is incorporated herein by reference.

[0168] Explanation of reference numerals

[0169] 1 Three-phase AC power source

[0170] 2 Primary side rectifier

[0171] 3 Smoothing capacitor

[0172] 4 Switching element

[0173] 5 Transformer

[0174] 6 Secondary side rectifier

[0175] 7 Reactor

[0176] 30 Inverter drive unit

[0177] 31 Current detection unit

[0178] 32 Voltage detection unit

[0179] 33 Disconnection detection unit

[0180] 34 Current error amplification unit

[0181] 35 Feed setting data unit

[0182] 36 Current setting unit

[0183] 36A Target current setting unit

[0184] 36B Wire tip position conversion unit

[0185] 36C Voltage setting unit

[0186] 37 Waveform control table linear operation unit

[0187] 38 Phase delay correction unit

[0188] 39 Push control unit

[0189] 40 A / D input unit

[0190] 41 Electric angle adjustment unit

[0191] 42 Digital communication unit

[0192] 43 Welding sequence unit

[0193] 50 Welding system

[0194] 100 Welding wire

[0195] 110 Welding robot

[0196] 111 Torch

[0197] 120 Welding control device

[0198] 122 Digital communication unit

[0199] 123 Digital communication unit

[0200] 140 Welding power source

[0201] 141 Control system unit

[0202] 150 Controller

[0203] 160 Servo amplifier

[0204] 161 Forward and reverse feed command generation unit

[0205] 162 Digital communication unit

[0206] 163 Synchronization signal generation unit

[0207] 170 Servo motor

[0208] 180 Pushing motor

[0209] 190 Wire buffer

[0210] 191 Serial-to-analog conversion unit

[0211] 200 Workpiece

Claims

1. A welding system is used to feed the front end of a welding wire towards a base material while periodically repeating the feeding with a cycle of forward feeding period and reverse feeding period, and controls at least one of the welding conditions based on at least one of the front end position and the feeding speed of the welding wire. The welding system is characterized in that the welding system at least includes a welding control device, a welding power source, a servo motor, and a servo amplifier for controlling the servo motor. At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication. The servo amplifier has: a unit for generating a feeding instruction for forward feeding or reverse feeding based on the setting information input through the digital communication; a unit for outputting a control signal based on the generated feeding instruction to the servo motor; and a unit for outputting a synchronization signal related to the generated feeding instruction to the welding power source. The welding power source has a unit for calculating the wire position phase based on the synchronization signal.

2. The welding system according to claim 1, characterized in that the synchronization signal is a signal based on at least one of the wire position phase and the speed phase of the feeding speed.

3. The welding system according to claim 2, characterized in that the servo amplifier has a unit for inputting the setting information and the operation signal of the servo motor and calculating the difference between the generated feeding instruction and the operation signal of the servo motor. The welding power source has a unit for controlling the welding conditions based on the difference and the synchronization signal.

4. The welding system according to claim 2, characterized in that the welding power source has the following unit: having a database including data obtained by previously calculating the difference between the setting information and the operation signal of the servo motor, and controlling the welding conditions based on the database and the synchronization signal.

5. The welding system according to any one of claims 1 to 4, characterized in that the setting information includes at least one set value of average feeding speed, wire amplitude, wire forward and reverse frequency, and wire forward and reverse period.

6. The welding system according to any one of claims 1 to 4, characterized in that the welding power source and the servo amplifier are at least connected by analog input and output. The synchronization signal is at least input from the servo amplifier to the welding power source through the analog input and output.

7. The welding system according to any one of claims 1 to 4, characterized in that the welding system includes a wire buffer device and a pushing motor. The wire buffer device has a sensor for detecting the buffer amount of the wire. The welding power source has a unit for controlling the pushing motor based on the input buffer amount.

8. A feeding control method feeds the front end of a welding wire towards a base material while periodically repeating the feeding with a cycle of forward feeding period and reverse feeding period, and performs welding while controlling at least one of the welding conditions based on at least one of the front end position and the feeding speed of the welding wire. Among them, In a welding system including at least a welding control device, a welding power source, a servo motor, and a servo amplifier for controlling the servo motor, at least the servo amplifier and the welding power source are directly or indirectly connected by digital communication. The servo amplifier generates a feed command for forward feed or reverse feed based on setting information input through the digital communication. The servo amplifier outputs a control signal based on the generated feed command to the servo motor. The servo amplifier outputs a synchronization signal related to the generated feed command to the welding power source. The welding power source calculates the wire position phase based on the synchronization signal.

9. A communication connection method for communication between devices constituting a welding system, the welding system periodically and repeatedly feeds the front end of a welding wire in a cycle with a forward feed period and a reverse feed period while feeding it toward a base material, and controls at least one of welding conditions based on at least one of the front end position and feed speed of the welding wire. The welding system includes at least a welding control device, a welding power source, a servo motor, and a servo amplifier for controlling the servo motor. At least the servo amplifier and the welding power source are directly or indirectly connected by digital communication. The servo amplifier generates a feed command for forward feed or reverse feed based on setting information input through digital communication from a device other than the servo amplifier among the devices constituting the welding system. The servo amplifier outputs a control signal based on the generated feed command to the servo motor. The servo amplifier outputs a synchronization signal related to the generated feed command to the welding power source. The welding power source calculates the wire position phase based on the synchronization signal.

10. The communication connection method according to claim 9, wherein the digital communication is digital communication connected using an industrial field network, and it is linearly connected in the order of the servo amplifier, the welding control device, the welding power source, or in the order of the servo amplifier, the welding power source, the welding control device.

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