Welding power supply device and arc welding device provided with same

Abstract

A welding power supply device 40 comprises a main circuit 10, a control unit 20, and a high-frequency generating circuit 30. The main circuit 10 is connected to an electrode 52 provided in a welding torch 50. The high-frequency generating circuit 30 has a charging unit 33, a charging switch 32, and a discharging switch 34. While a torch signal STS is in an ON state, the control unit 20 activates the charging switch 32 to charge the charging unit 33, and stops the charging switch 32 after the lapse of a charging time T1. After the charging is completed, the discharging switch 34 is activated to discharge the charging unit 33, and after the lapse of a discharging time T2, the discharging switch 34 is stopped. By the discharge of the charging unit 33, the high-frequency generating circuit 30 generates a high-frequency voltage VRF only once.

Description

Welding power supply and arc welding device equipped with same

[0001] The present disclosure relates to a welding power supply, and more particularly to a welding power supply for performing non-consumable electrode arc welding, and an arc welding apparatus including the same.

[0002] In non-consumable electrode arc welding devices such as those used in TIG (Tungsten Inert Gas) welding, a high-frequency voltage arc start method is often used to generate an arc by exciting the arc while keeping the base material and the electrode attached to the welding torch in a non-contact state.

[0003] Patent Document 1 discloses an electric discharge machining system having a machining torch, an electric discharge machining power supply, and a high-frequency generator, in which a discharge occurs in a spark gap connected to the capacitor by charging and discharging a capacitor provided in the high-frequency generating circuit. When a discharge occurs in the spark gap, a high-frequency voltage is generated between a base material connected to a coupling coil and an electrode provided in the machining torch via a coupling coil connected to the spark gap. The high-frequency voltage causes a dielectric breakdown between the base material and the electrode, generating an arc.

[0004] Patent No. 6260007

[0005] In recent years, robots that hold and move welding torches in arc welding have become increasingly sophisticated, and the number of electronic components mounted on them has increased accordingly. There is also a demand for attaching measuring devices such as cameras and sensors to the tips of welding torches and robots to monitor the welding state.

[0006] Typically, non-consumable electrode arc welding devices generate high-frequency voltage multiple times to ensure reliable arc start. In this case, even after an arc is generated with the first high-frequency voltage, the high-frequency voltage is generated multiple times. Furthermore, as shown in Patent Document 1, generating the high-frequency voltage typically utilizes a discharge generated in a spark gap. This discharge, as well as the discharge between the electrode and the base metal, generates high-frequency noise.

[0007] However, the electronic components and measuring instruments mentioned above have the risk of malfunctioning due to high frequency noise.

[0008] The present disclosure has been made in view of the above points, and an object thereof is to provide a welding power supply capable of reducing high-frequency noise at the time of arc start, and an arc welding apparatus equipped with the same.

[0009] In order to achieve the above object, a welding power supply according to the present disclosure is a welding power supply used for non-consumable electrode arc welding, and includes at least a main circuit, a high frequency generating circuit, and a control unit, wherein the main circuit is electrically connected to an electrode provided on a welding torch and supplies a welding output to the electrode, and the high frequency generating circuit includes at least a charging unit, a charge switch, and a discharge switch, each electrically connected to the charging unit, and while a torch signal of a torch switch provided on the welding torch is in an on state, the control unit operates the high frequency generating circuit in a first mode, and in the first mode, the control unit activates the charging switch to charge the charging unit, stops the charging switch after a predetermined charging time has elapsed since charging of the charging unit started, activates the discharge switch after stopping the charging switch to discharge the charging unit, and stops the discharge switch after a predetermined discharge time has elapsed since discharging of the charging unit started, thereby causing the high frequency generating circuit to generate a high frequency voltage having a predetermined voltage peak value between the base metal and the electrode only once.

[0010] Another welding power supply according to the present disclosure is a welding power supply used for non-consumable electrode arc welding, and includes at least a main circuit, a high frequency generating circuit, and a control unit, the main circuit is electrically connected to an electrode provided on a welding torch and supplies a welding output to the electrode, the high frequency generating circuit has at least a charging unit, and a charging switch and a discharging switch each electrically connected to the charging unit, the control unit has a signal stop time set in the control unit from the end of discharging of the charging unit to the start of the next charging, the control unit operates the high frequency generating circuit in a second mode while the torch signal of the torch switch provided on the welding torch is in an on state, the control unit in the second mode activates the charging switch to charge the charging unit, and deactivates the charging switch after a predetermined charging time has elapsed since the start of charging of the charging unit After the charging switch is stopped, the discharge switch is activated to discharge the charging unit, and after a predetermined discharge time has elapsed since the start of discharging of the charging unit, the discharge switch is stopped and the charging unit is discharged, thereby causing the high-frequency generating circuit to generate the high-frequency voltage having the voltage peak value between the base material and the electrode, and after the signal stop time has elapsed since the discharge switch was stopped, the charging switch is activated again to charge the charging unit, and until it detects that an arc has occurred between the base material and the electrode or the torch signal of the torch switch is turned off, the control unit repeatedly executes a series of operations from starting the charging switch to stopping the discharge switch, thereby causing the high-frequency generating circuit to repeatedly generate the high-frequency voltage between the base material and the electrode at a predetermined cycle.

[0011] The arc welding apparatus according to the present disclosure comprises at least the welding power supply and the welding torch connected to the welding power supply, wherein the welding torch is provided with the torch switch that generates the torch signal, and the control unit operates the high-frequency generating circuit by operating the torch switch.

[0012] According to the present disclosure, high frequency noise at the time of arc start can be reduced.

[0013] FIG. 1 is a schematic diagram of an arc welding apparatus according to a first embodiment. FIG. 2 is a schematic diagram of a control block in the arc welding apparatus. FIG. 3A is a flowchart showing an arc start procedure. FIG. 3B is a flowchart showing a first charge / discharge process procedure. FIG. 4 is a time chart of various output waveforms at the time of arc start. FIG. 5A is a diagram showing a time waveform of a high-frequency voltage generated at the time of arc start according to the first embodiment. FIG. 5B is a diagram showing a time waveform of a high-frequency voltage generated at the time of arc start according to the second embodiment. FIG. 6A is a flowchart showing an arc start procedure according to the third embodiment. FIG. 6B is a flowchart showing a second charge / discharge process procedure. FIG. 7 is a time chart of various output waveforms at the time of arc start according to the third embodiment. FIG. 8 is a flowchart showing an arc start procedure according to the fourth embodiment. FIG. 9 is a flowchart showing another arc start procedure according to the fourth embodiment. FIG. 10 is a schematic diagram of an arc welding apparatus according to a first modification. FIG. 11 is a schematic diagram of an arc welding apparatus according to a second modification. FIG. 12 is a schematic diagram of an arc welding apparatus according to a third modification.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely exemplary in nature and is not intended to limit the present disclosure, its applications, or its uses.

[0015] (Embodiment 1) [Configuration of Arc Welding Apparatus] Fig. 1 is a schematic configuration diagram of an arc welding apparatus according to embodiment 1. Fig. 2 is a schematic configuration diagram of a control block in the arc welding apparatus.

[0016] As shown in FIG. 1 , arc welding apparatus 70 includes welding power supply 40, welding torch 50, first power cable 61, second power cable 62, and torch switch cable 63. First power cable 61 electrically connects main circuit 10 of welding power supply 40 to electrode 52 held by welding torch 50. Electrode 52 is a non-consumable electrode. Second power cable 62 electrically connects main circuit 10 of welding power supply 40 to base material 80, which is the workpiece to be welded. Torch switch cable 63 electrically connects control unit 20 of welding power supply 40 to torch switch 51 provided on welding torch 50. First power cable 61 and torch switch cable 63 may be combined into a single composite cable. A gas pipe (not shown) for supplying shielding gas to welding torch 50 may also be connected. In this case, the gas pipe may be combined into the composite cable.

[0017] The welding power supply 40 includes a main circuit 10, a control unit 20, and a high-frequency generating circuit 30. The main circuit 10 is electrically connected to an electrode 52 provided on a welding torch 50 and supplies a welding output to the electrode 52. The main circuit 10 includes a primary rectifier 11, an inverter 12, a first transformer 13, a secondary rectifier 14, a welding current detector 15, and a welding voltage detector 16. The primary rectifier 11 includes, for example, a diode and a capacitor. The primary rectifier 11 rectifies an AC voltage input to the welding power supply 40 from a three-phase AC power supply 90 into a first DC voltage. The inverter 12 includes a plurality of switching elements, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors). The inverter unit 12 converts the first DC voltage rectified by the primary side rectifier unit 11 into an AC voltage by opening and closing a switching element. The inverter unit 12 converts a torch signal S generated by operating a torch switch 51 into an AC voltage. ＴＳThe first transformer 13 transforms the AC voltage output from the inverter unit 12. The secondary side rectifier 14 has a configuration similar to that of the primary side rectifier 11, and rectifies the AC voltage output from the first transformer 13 to a second DC voltage. The welding current detector 15 detects the welding current flowing through the electrode 52. The welding voltage detector 16 detects the welding voltage between the base material 80 and the electrode 52.

[0018] The control unit 20 includes a control power supply 21, a control processor 22, and an input unit 23. The control unit 20 may include a storage unit (not shown). The control unit 20 may also include other functional blocks. As shown in FIG. 1 , the control power supply 21 receives the inter-phase voltages of two phases of a three-phase AC power supply 90. The control power supply 21 is also connected to both ends of the input coil of a second transformer 31 in the high-frequency generating circuit 30. The control power supply 21 steps down the input inter-phase voltage, i.e., AC voltage, and converts it into a DC power supply voltage with a constant voltage value, which is then input to the input coil of the second transformer 31. In this embodiment, the power supply voltage output from the control power supply 21 is +24 V, but is not limited to this. The input unit 23 is configured with an input device such as a keyboard, a touch panel, or a rotary switch. The welding conditions are set by operating the input unit 23. The charging time T1, discharging time T2, and signal stop time T3, which will be described later, can also be changed by operating the input unit 23. Note that input unit 23 may be configured to be able to communicate with control unit 20 and may be provided outside welding power supply 40 .

[0019] The control processor 22 is composed of one or more CPUs (Central Processing Units). The CPU has a memory area (not shown) composed of ROM (Read Only Memory), RAM (Random Access Memory), etc. The control processor 22 may have components other than the CPU. The control processor 22 receives the above-mentioned torch signal S ＴＳ is input. Torch signal S ＴＳWhen the torch signal S is turned on, the control processor 22 sends a drive signal to the inverter unit 12, and the inverter unit 12 receives the drive signal and operates to convert the first DC voltage into an AC voltage. ＴＳ When the control processor 22 is turned on, it sends a drive signal to the high frequency generating circuit 30, which then operates. This will be described in more detail later.

[0020] The high-frequency generating circuit 30 includes a second transformer 31, a charging switch 32, a charging unit 33, a discharging switch 34, and a coupling coil 35. All components of the high-frequency generating circuit 30, except for the coupling coil 35, are mounted on a single circuit board 37. The input coil of the second transformer 31 is connected to the control power supply 21. The second transformer 31 transforms the power supply voltage input from the control power supply 21. The charging switch 32 is disposed between the control power supply 21 and the input coil of the second transformer 31 and is electrically connected to the control power supply 21 and the input coil. The charging switch 32 is configured, for example, by a semiconductor switching element such as a MOSFET, an IGBT, or a bipolar transistor. However, this is not limited thereto, and the charging switch 32 may also be a relay switch. It is preferable that the charging switch 32 responds quickly to input signals, has low on-resistance, and is capable of passing a large current. The charging unit 33 is configured, for example, by a capacitor with a predetermined capacitance. The discharging switch 34 is connected in series with the charging unit 33 and the coupling coil 35. The discharge switch 34 is composed of a semiconductor switching element, similar to the charge switch 32. However, this is not limited thereto, and the discharge switch 34 may also be a relay switch. It is preferable that the discharge switch 34 has a large time change in the current flowing through it, i.e., a large di / dt, so that a large current can flow instantaneously. The coupling coil 35 is a type of transformer, and the input coil is connected to the charging unit 33 via the discharge switch 34. The output coil is connected in series to the second power cable 62. When the discharge switch 34 is turned on, the charge accumulated in the charging unit 33 is discharged. When a current flows in the input coil based on this charge, a voltage is induced in the output coil. Depending on the amount of charge accumulated in the charging unit 33, the time for which the current flows in the input coil is approximately several microseconds to several tens of microseconds, and therefore a voltage with a frequency of several hundred kHz to 1 MHz or more is induced in the output coil. This voltage is applied to the base material 80, generating a voltage of the same frequency between the base material 80 and the electrode 52. In the following description, the voltage generated between the base material 80 and the electrode 52 by the discharge from the charging part 33 is referred to as the high-frequency voltage V ＲＦ The high frequency voltage V ＲＦ The voltage peak value VＰ The circuit constants of the high frequency generating circuit 30 and the charging time T1 are set so that the voltage is 15 kV or less or 20 kV or less.

[0021] The operation of the arc welding device 70 will now be briefly described.

[0022] With the welding power supply 40 connected to the three-phase AC power supply 90, the torch switch 51 is operated to output the torch signal S ＴＳ When the torch switch cable 63 is turned on, the torch signal S ＴＳ is input to the control processor 22. The torch signal S ＴＳ The control processor 22, upon receiving the signal, operates the inverter unit 12 of the main circuit 10 at a predetermined cycle. As a result, a current flows intermittently through the input coil of the first transformer 13, and a periodically fluctuating voltage is induced in the output coil. The voltage induced in the output coil is rectified by the secondary rectifier 14, and the rectified second DC voltage is applied between the electrode 52 electrically connected to the first power cable 61 and the base material 80 electrically connected to the second power cable 62.

[0023] Also, the torch signal S ＴＳ Upon receiving this signal, the control processor 22 opens and closes the charge switch 32 and the discharge switch 34 at predetermined timings. This causes the charger 33 to be charged, and after charging is stopped, the charger 33 is discharged by the discharge switch 34. This causes the high-frequency voltage V ＲＦ The second DC voltage is applied to the base material 80, generating a micro-arc ARC. The generation of the micro-arc ARC generates an arc between the base material 80 and the electrode 52 in accordance with the second DC voltage, and the base material 80 is welded by heat input from the arc.

[0024] [Arc start method] Fig. 3A is a flowchart showing an arc start procedure, Fig. 3B is a flowchart showing a first charge / discharge process procedure, and Fig. 4 is a time chart of various output waveforms at the time of arc start.

[0025] The arc start procedure shown in FIG. 3A is performed by applying the high frequency voltage V ＲＦThe control processor 22 reads out the charging time T1 stored in the memory area and sets it in the calculation area (not shown) (step S1). Next, the control processor 22 reads out the discharging time T2 stored in the memory area and sets it in the calculation area (not shown) (step S2). If the control unit 20 is provided with a storage unit, the charging time T1 and the discharging time T2 may be stored in the storage unit. After steps S2 have been executed, the torch switch 51 is operated to generate the torch signal S ＴＳ is turned on (step S3), the first charge / discharge process is executed (step S4).

[0026] As shown in FIG. 3B, when the first charging / discharging process starts, the control processor 22 outputs the charging signal S ＣＧ is output to the charging switch 32 (step S11), which activates and turns on the charging switch 32. At the same time as the start of step S11, a charging timer is turned on (step S12). Note that this charging timer operates on software and is realized using the timing function of the control processor 22.

[0027] When steps S11 and S12 start, a current flows from the output coil of the second transformer 31 to the charging unit 33 via the charging switch 32, and the charging unit 33 is charged. ＣＧ At the same time as the output of the charging signal S starts, the charging timer starts counting the charging time T1. The charging time T1 may be counted up or down. As shown in FIG. ＣＧ maintains the H potential (high potential) until the charging time T1 has elapsed, and during this time, the charging switch 32 is on, so charging to the charging section 33 continues.

[0028] Next, the control unit 20 determines whether charging of the charging unit 33 has been completed (step S13). In the example shown in this embodiment, whether charging of the charging unit 33 has been completed is determined based on whether the time counted by the charging timer has reached the charging time T1.

[0029] If the determination result in step S13 is negative, that is, if the charging of the charging unit 33 has not been completed, the control processor 22 continues charging the charging unit 33. If the determination result in step S13 is positive, that is, if the charging of the charging unit 33 has been completed, the control processor 22 outputs the charging signal S ＣＧ Specifically, the control processor 22 ends the output of the charging signal S ＣＧ The charging signal S is changed from the H potential to the L potential (low potential). ＣＧ When the charge signal S goes to L potential, the charge switch 32 turns off and charging to the charger 33 stops. ＣＧ When the output of the discharge signal S ＤＣＧ is output to the discharge switch 34 (step S15), and the discharge switch 34 is activated and turned on. At the same time as the start of step S15, the discharge timer is turned on (step S16). Note that the discharge timer, like the charge timer, operates on software and is realized using the timing function of the control processor 22.

[0030] When steps S15 and S16 start, a current flows from the charging unit 33 to the input coil of the coupling coil 35 via the discharge switch 34, and a voltage corresponding to the mutual inductance of the coupling coil 35 is induced in the output coil of the coupling coil 35. As a result, a voltage peak value of V is generated between the base material 80 connected to the output coil of the coupling coil 35 and the electrode 52 held by the welding torch 50. Ｐ A pulsed high frequency voltage V ＲＦ occurs.

[0031] In addition, the discharge signal S ＤＣＧ At the same time as the output of the discharge signal S starts, the discharge timer starts counting the discharge time T2. The counting method for the charge time T1 may be counting up or counting down. As shown in FIG. ＤＣＧmaintains the H potential until the discharge time T2 has elapsed, and during this time, the discharge switch 34 is on, so discharging continues until the amount of charge accumulated in the charging unit 33 falls below a predetermined value. Note that the discharge time T2 is determined by the amount of charge accumulated in the charging unit 33 and the impedance of the path from the charging unit 33 to the coupling coil 35. The amount of accumulated charge is determined by the capacitance of the charging unit 33 and the charging time T1. Therefore, it can be said that the discharge time T2 is determined by the charging time T1.

[0032] Next, the control unit 20 determines whether or not the discharge from the charging unit 33 has been completed (step S17). In the example shown in this embodiment, the control unit 20 determines whether or not the discharge from the charging unit 33 has been completed based on whether or not the time counted by the discharge timer has reached the discharge time T2.

[0033] If the determination result in step S17 is negative, that is, if the discharge from the charging unit 33 has not been completed, the control processor 22 continues discharging from the charging unit 33. If the determination result in step S17 is positive, that is, if the discharge from the charging unit 33 has been completed, the control processor 22 outputs the charging signal S ＣＧ (Step S18). Specifically, the control processor 22 ends the output of the discharge signal S ＤＣＧ The discharge signal S is transitioned from the H potential to the L potential. ＤＣＧ When the potential of the charger 33 becomes L, the discharge switch 34 is turned off and the discharge from the charger 33 is stopped.

[0034] 3A and 3B and the time chart shown in FIG. 4, when starting the arc, the control processor 22 operates the high frequency generating circuit 30 to generate a high frequency voltage V between the base material 80 and the electrode 52. ＲＦ The operation mode of the high frequency generating circuit 30 shown in this embodiment is called a first mode.

[0035] As described above, welding power supply 40 according to this embodiment is used for non-consumable electrode arc welding. Welding power supply 40 includes at least main circuit 10, control unit 20, and high frequency generating circuit 30.

[0036] Main circuit 10 is electrically connected to electrode 52, which is a non-consumable electrode provided on welding torch 50, and supplies welding output to electrode 52. High frequency generating circuit 30 has at least a charging unit 33, and a charging switch 32 and a discharging switch 34, each electrically connected to charging unit 33.

[0037] The torch signal S of the torch switch 51 provided on the welding torch 50 ＴＳ is in the ON state, the control unit 20 operates the high frequency generating circuit 30 in the first mode.

[0038] In the first mode, the control unit 20 performs the following series of controls. First, the charge switch 32 is activated to charge the charging unit 33. Then, after a charging time T1 has elapsed since the charging unit 33 started charging, the charge switch 32 is deactivated. After the charging unit 33 has finished charging, the discharge switch 34 is activated to discharge the charging unit 33, and after a discharging time T2 has elapsed since the discharging of the charging unit 33 started, the discharge switch 34 is deactivated. By the control unit 20 discharging the charging unit 33, the high-frequency generating circuit 30 generates a predetermined voltage peak value V between the base material 80 and the electrode 52. Ｐ a high frequency voltage V ＲＦ occurs only once.

[0039] According to this embodiment, the control unit 20 controls the operation of the high frequency generating circuit 30 so that the charging unit 33 is charged and discharged only once. In this way, the high frequency voltage V ＲＦ This allows the high frequency voltage V ＲＦ As a result, malfunctions of the electronic components and measuring instruments described above can be prevented, and the arc welding device 70 can be operated stably.

[0040] In addition, when the arc starts, the high frequency voltage V ＲＦA configuration in which a high-frequency voltage is generated only once is also disclosed in Patent Document 1, but in this configuration, a spark gap is an essential component. However, discharge through a spark gap generates a large amount of high-frequency noise. In addition, once the gap distance is set, it is fixed at that value. Therefore, the voltage peak value of the high-frequency voltage is also fixed. In addition, the generation time of the high-frequency voltage is also fixed.

[0041] On the other hand, according to this embodiment, the high frequency voltage V ＲＦ Therefore, the amount of generated high frequency noise can be reduced compared to the conventional configuration disclosed in Patent Document 1. In addition, by appropriately setting the charging time T1 and the discharging time T2 and changing them as necessary, the high frequency voltage V ＲＦ The occurrence time and voltage peak value V Ｐ This makes it possible to reliably start the arc while reducing high frequency noise.

[0042] The main circuit 10 has at least a primary side rectifier 11, an inverter unit 12, a first transformer 13, and a secondary side rectifier 14. The primary side rectifier 11 rectifies an AC voltage input from a three-phase AC power supply 90, which is an external power supply. The inverter unit 12 converts a first DC voltage rectified by the primary side rectifier 11 into an AC voltage. The first transformer 13 transforms the AC voltage output from the inverter unit 12. The secondary side rectifier 14 converts the AC voltage transformed by the first transformer 13 into a second DC voltage.

[0043] By configuring the main circuit 10 in this manner, it is possible to convert the power input from an external power source into power suitable for arc welding.

[0044] A switching unit (not shown) that operates in response to a control signal from the control unit 20 may be provided downstream of the secondary side rectifier unit 14. In this way, pulse welding and AC arc welding can be performed.

[0045] Preferably, the high frequency generating circuit 30 further includes a second transformer 31 and a coupling coil 35. In this case, the charging unit 33 is connected in parallel to the output coil of the second transformer 31. The input coil of the coupling coil 35 is connected to the charging unit 33 and the discharge switch 34. The output coil of the coupling coil 35 is connected to the secondary rectifier 14 of the main circuit 10 and the base material 80.

[0046] By configuring the high frequency generating circuit 30 in this manner, it is possible to accumulate electric charges in the charging section 33. In addition, a high frequency voltage is induced in the coupling coil 35 based on the electric charges discharged from the charging section 33, and a high frequency voltage V ＲＦ can be generated.

[0047] The control unit 20 has a control power supply 21 connected to a three-phase AC power supply 90. The control power supply 21 converts the AC voltage input from the three-phase AC power supply 90 into a DC power supply voltage with a constant voltage value. The power supply voltage is input to an input coil of a second transformer 31.

[0048] By providing a control power supply 21 and inputting the power supply voltage, which is the output voltage of the control power supply 21, to the input coil of the second transformer 31, it is possible to stabilize the voltage across the output coil of the second transformer 31. As a result, when the charging switch 32 is turned on, the amount of charge stored in the charging unit 33 and therefore the current flowing through the coupling coil 35 are kept constant, and the high-frequency voltage V ＲＦ The voltage peak value V Ｐ This can suppress fluctuations.

[0049] In this embodiment, the charging switch 32 is disposed between the control power supply 21 and the input coil of the second transformer 31, and is electrically connected to the control power supply 21 and the input coil. More specifically, the charging switch 32 is connected in series to the control power supply 21 and the input coil of the second transformer 31.

[0050] Arc welding apparatus 70 according to this embodiment includes at least welding power supply 40 and welding torch 50 connected to welding power supply 40. Welding torch 50 receives torch signal S ＴＳBy operating the torch switch 51, the control unit 20 activates the high frequency generating circuit 30.

[0051] By configuring the arc welding device 70 in this manner, the high frequency voltage V ＲＦ This reduces the high frequency noise caused by the above-mentioned problems. This prevents malfunctions of the electronic components and measuring instruments, and allows the arc welding device 70 to operate stably. Furthermore, a stable arc start can be achieved, reducing welding defects and achieving high welding quality.

[0052] (Embodiment 2) Fig. 5A is a diagram showing the time waveform of a high-frequency voltage generated at the time of arc start according to embodiment 1. Fig. 5B is a diagram showing the time waveform of a high-frequency voltage generated at the time of arc start according to embodiment 2. For ease of explanation, in Figs. 5A and 5B and the following drawings, parts that are the same as those in embodiment 1 are designated by the same reference numerals, and detailed explanations thereof will be omitted.

[0053] The high frequency voltage V ＲＦ When generating a voltage peak value V, if the charging time T1 is 6 msec, Ｐ was about 10 kV to 11 kV (see FIG. 5A).

[0054] On the other hand, in this embodiment, the charging time T1 is changed from 6 msec to 4 msec, so that the voltage peak value V Ｐ１ is reduced to about 6 kV to 7 kV (see FIG. 5B).

[0055] As described above, the charging time T1 determines the amount of charge stored in the charging unit 33, and the amount of charge determines the voltage induced in the coupling coil, in other words, the high-frequency voltage V ＲＦ Determine the voltage peak value of

[0056] Therefore, as shown in this embodiment, by shortening the charging time T1 set and stored in the control unit 20, the high frequency voltage V ＲＦThis allows the voltage peak value of the high frequency voltage V to be reduced while taking into consideration the stability of the arc start, in this case, whether the arc can be started reliably with one arc generation, and the magnitude of the high frequency noise that depends on the voltage peak value. ＲＦ The voltage peak value can be adjusted.

[0057] The charging time T1 may be changed by directly inputting it through the input unit 23. Alternatively, different charging times T1 may be stored in advance in the memory area of ​​the control processor 22, and a desired charging time T1 may be selected by operating the input unit 23.

[0058] (Embodiment 3) In embodiment 1, at the time of arc start, the high frequency generating circuit 30 generates a high frequency voltage V between the base material 80 and the electrode 52. ＲＦ On the other hand, when welding power supply 40 and base material 80 are disposed apart from each other, the lengths of first power cable 61 and second power cable 62 also become longer depending on the distance between welding power supply 40 and base material 80.

[0059] However, if the first power cable 61 is long, the voltage drops inside the first power cable 61, making it difficult for an arc to occur. ＲＦ This makes it difficult to start the arc.

[0060] Therefore, in this embodiment, the torch signal S ＴＳ While is in the on state, the high frequency voltage V ＲＦ By generating this multiple times, the arc is reliably started. This will be explained in more detail below.

[0061] Fig. 6A is a flowchart showing an arc start procedure according to embodiment 3. Fig. 6B is a flowchart showing a second charge / discharge process procedure. Fig. 7 is a time chart of various output waveforms at the time of arc start according to embodiment 3.

[0062] 6A are similar to steps S1 and S2 shown in Fig. 3A, and therefore will not be described in detail. However, the charging time T1 and the discharging time T2 in this embodiment may be the same as or different from the charging time T1 and the discharging time T2 shown in the first embodiment.

[0063] In step S23 following step S22, the control processor 22 reads out the signal stop time T3 stored in the memory area and sets it in a calculation area (not shown). ＤＣＧ The next charging signal S ＣＧ is the time from the L state to the H state. The processes of steps S21 to S23 may be executed in parallel.

[0064] Next, the welding operator operates the torch switch 51 to turn on the activation signal of the torch switch 51 (step S24). ＴＳ Furthermore, the second charge / discharge process is executed (step S25), and thereafter the control processor 22 turns on the torch signal S ＴＳ It is determined whether the torch signal S is ON (step S26). ＴＳ If it is in the OFF state, the entire process ends.

[0065] On the other hand, if the determination result in step S26 is affirmative, that is, the torch signal S ＴＳ is in the ON state, the control processor 22 determines whether the arc start has been successful (step S27). If the determination result in step S27 is negative, that is, if an arc has not been generated, the process returns to step S25 and executes the processes from step S25 onwards.

[0066] If the determination result in step S27 is affirmative, that is, if the arc start is successful, the entire process ends.

[0067] For convenience of explanation, FIG. 6A shows steps S26 and S27 as being processed sequentially, but in reality, steps S26 and S27 are processed in parallel.

[0068] Here, steps S31 to S38 of the second charge / discharge process shown in Fig. 6B are the same as steps S11 to S18 of the first charge / discharge process shown in Fig. 3B, and therefore will not be described here. On the other hand, the flowchart shown in Fig. 6B differs from the flowchart shown in Fig. 3B in that steps S39 and S40 are executed after step S38.

[0069] When the discharge from the charging unit 33 is completed, in step S38, the control processor 22 outputs the charging signal S ＣＧ The output of the second charge / discharge process is terminated. Subsequently, the charge timer is turned off (step S39), and the discharge timer is turned off, thereby terminating the second charge / discharge process (step S40). By turning off the charge timer in step S39, counting of the charge time T1 is stopped. Furthermore, the charge timer is reset, and when it is turned on again, it starts counting the set charge time T1 again. Similarly, by turning off the discharge timer in step S40, counting of the discharge time T2 is stopped. Furthermore, when it is reset, and when it is turned on again, it starts counting the set discharge time T2 again. In this embodiment, the control processor 22 determines whether the charge timer and the discharge timer are each turned off, and if they are off, the charge timer and the discharge timer are set to turn on again.

[0070] 6A and 6B and the time chart shown in FIG. 7, when starting an arc, the control processor 22 operates the high frequency generating circuit 30 as follows: That is, when it detects that an arc has been generated between the base material 80 and the electrode 52, or when it detects that the torch signal S of the torch switch 51 has been generated, the control processor 22 operates the high frequency generating circuit 30 as follows: ＴＳ The control processor 22 repeatedly executes a series of operations from activating the charging switch 32 to deactivating the discharging switch 34 until the torch signal S ＴＳ While the is in the on state, a high frequency voltage V is applied between the base material 80 and the electrode 52.ＲＦ The operation mode of the high frequency generating circuit 30 shown in this embodiment is called a second mode.

[0071] As described above, welding power supply 40 according to this embodiment is used for non-consumable electrode arc welding. Welding power supply 40 includes at least main circuit 10, control unit 20, and high frequency generating circuit 30.

[0072] Main circuit 10 is electrically connected to electrode 52, which is a non-consumable electrode provided on welding torch 50, and supplies welding output to electrode 52. High frequency generating circuit 30 has at least a charging unit 33, and a charging switch 32 and a discharging switch 34, each electrically connected to charging unit 33.

[0073] A signal stop time T3 from the end of discharge of the charging unit 33 to the start of the next charge is set in the control unit 20. The torch signal S of the torch switch 51 provided in the welding torch 50 is ＴＳ is in the ON state, the control unit 20 operates the high frequency generating circuit 30 in the second mode.

[0074] In the second mode, the control unit 20 performs the following series of controls. First, the charge switch 32 is activated to charge the charging unit 33. Then, after a charging time T1 has elapsed since the charging unit 33 started charging, the charge switch 32 is deactivated. After the charging unit 33 has finished charging, the discharge switch 34 is activated to discharge the charging unit 33, and after a discharging time T2 has elapsed since the discharging of the charging unit 33 started, the discharge switch 34 is deactivated. By the control unit 20 discharging the charging unit 33, the high-frequency generating circuit 30 generates a predetermined voltage peak value V between the base material 80 and the electrode 52. Ｐ a high frequency voltage V ＲＦ After the signal stop time T3 has elapsed since the discharging switch 34 was turned off, the charging switch 32 is turned on again to charge the charging unit 33.

[0075] When an arc is generated between the base material 80 and the electrode 52, or when a torch signal S ＴＳThe control unit 20 repeatedly executes a series of operations from activating the charging switch 32 to deactivating the discharging switch 34 until the base material 80 is turned off. In this way, the high frequency generating circuit 30 generates a high frequency voltage V ＲＦ is repeatedly generated at a predetermined period T. As is clear from Fig. 4, the period T corresponds to the sum of the charging time T1, the discharging time T2, and the signal stop time T3.

[0076] According to this embodiment, the occurrence of an arc between the base material 80 and the electrode 52 is detected, or the torch signal S of the torch switch 51 is ＴＳ The control unit 20 controls the operation of the high frequency generating circuit 30 so that charging and discharging of the charging unit 33 are repeated until the power supply 52 is turned off. ＲＦ can be repeatedly generated at a predetermined period T. As a result, the first power cable 61 is long and the high frequency voltage V ＲＦ Even if it is difficult to start the arc by generating it only once, the arc can be started reliably.

[0077] In this embodiment, as in the second embodiment, the high-frequency voltage V ＲＦ This allows the voltage peak value of the high frequency voltage V ＲＦ The voltage peak value can be adjusted while taking into consideration the magnitude of high frequency noise that depends on the voltage peak value of the high frequency voltage V ＲＦ As a result, malfunctions of the electronic components and measuring instruments described above can be prevented, and the arc welding device 70 can be operated stably.

[0078] (Fourth embodiment) Fig. 8 is a flowchart showing an arc start procedure according to a fourth embodiment.

[0079] As shown in Fig. 8, the welding operator first operates input unit 23 to select the arc start operation mode (step S50). When the first mode is selected in step S50, the process proceeds to step S61 and subsequent steps. In the flowchart shown in Fig. 8, the processes executed in steps S61 to S64 are the same as the processes executed in steps S1 to S4 shown in Fig. 3A. In other words, in step S64, the same processes as steps S11 to S18 shown in Fig. 3B are executed.

[0080] Furthermore, if the second mode is selected in step S50, the process proceeds to step S71 and subsequent steps. The processes executed in steps S71 to S77 are the same as the processes executed in steps S21 to S27 shown in Fig. 6A. That is, in step S75, the same processes as those executed in steps S31 to S40 shown in Fig. 6B are executed.

[0081] As described above, welding power supply 40 according to this embodiment differs from welding power supply 40 according to embodiments 1 and 2 in that control unit 20 is configured to be able to switch between operating high-frequency generating circuit 30 in the first mode and operating high-frequency generating circuit 30 in the second mode.

[0082] By being able to switch between operation modes in this way, an appropriate arc start method can be selected depending on the environment in which the arc welding device 70 is installed.

[0083] Specifically, when many electronic components or the above-mentioned measuring instruments are arranged around welding torch 50, arc start can be performed in the first mode, which can suppress the generation of high-frequency noise. On the other hand, when the distance between welding power supply 40 and base material 80 is large and first power cable 61 and second power cable 62 are long, high-frequency voltage V ＲＦ The arc can be started in the second mode, which generates an arc, and the arc can be generated reliably.

[0084] According to this embodiment, the arc start in the first mode and the arc start in the second mode are combined to obtain the high frequency voltage V ＲＦThis allows for reliable arc start while taking into consideration the magnitude of high frequency noise that depends on the voltage peak value.

[0085] FIG. 9 is a flowchart showing another arc start procedure according to the fourth embodiment.

[0086] In the arc starting method shown in Fig. 9, first, the high frequency generating circuit 30 is operated in the first mode (step S81). The process performed in step S81 is the same as the process performed in steps S1 to S4 shown in Fig. 3A. That is, in step S81, a first charge / discharge process similar to steps S11 to S18 shown in Fig. 3B is performed.

[0087] Next, the control processor 22 determines whether the arc start has been successful (step S82). ＲＦ If the determination result in step S82 is affirmative, that is, if the arc start is successful, the arc start process is terminated.

[0088] On the other hand, if the determination result in step S82 is negative, that is, if the arc start is not successful, the high frequency voltage V ＲＦ After counting up the number of occurrences i to (i+1) (step S83), the processes of steps S81 and S82 are executed again. If the determination result of step S82 becomes negative again, the number of occurrences i is counted up to (i+1) again (step S83), and the control processor 22 determines whether the number of occurrences i has reached a predetermined upper limit (step S84). The processes of steps S81 and S82 are repeated until the determination result of step S82 becomes positive, or until the determination result of step S82 becomes positive, that is, until the number of occurrences i reaches the upper limit. In this embodiment, the upper limit of the number of occurrences i to be counted is set to 5, but this is not particularly limited and can be changed as appropriate.

[0089] High frequency voltage V ＲＦ If the arc start is not successful even when the number of occurrences i of reaches the upper limit, the first mode is switched to the second mode and the high frequency generating circuit 30 is operated (step S85).

[0090] According to the method shown in Figure 9, control unit 20 of welding power supply 40 first operates high frequency generating circuit 30 in the first mode, thereby attempting to start an arc while reducing the amount of high frequency noise generated during the arc start. If the arc start is unsuccessful, control unit 20 operates high frequency generating circuit 30 in the second mode for the first time, thereby ensuring a successful arc start even in an environment where an arc start is unlikely to occur. Furthermore, automatically changing the arc start method reduces the workload of the welding operator.

[0091] <Modification 1> FIG. 10 is a schematic diagram of an arc welding device according to Modification 1. As shown in FIG.

[0092] Welding power supply 40 of this modified example shown in FIG. 10 differs from welding power supply 40 of embodiment 1 shown in FIG. 1 in that charging switch 32 is connected in series with the output coil of second transformer 31 and charging unit 33, and is electrically connected to the output coil and charging unit 33.

[0093] In the example shown in Fig. 10, since the charging switch 32 is disposed in the position described above, it is preferable that the charging switch 32 has a high withstand voltage. On the other hand, the current driving capability does not need to be higher than that of the charging switch 32 shown in Fig. 1. In the example shown in Fig. 1, since the charging switch 32 is disposed in the position described above, it is not necessary that the withstand voltage of the charging switch 32 is higher than that of the charging switch 32 in the position shown in Fig. 10. On the other hand, it is preferable that the current driving capability of the charging switch 32 shown in Fig. 1 is higher than that of the charging switch 32 shown in Fig. 10.

[0094] In this way, the specifications and arrangement of charging switch 32 in welding power supply 40 can be changed as appropriate depending on the withstand voltage and current driving capacity required of charging switch 32.

[0095] Furthermore, according to this modification, it is possible to achieve the same effect as that achieved by the configuration shown in the first embodiment. That is, at the time of arc start, the high frequency voltage V ＲＦThis can reduce the high frequency noise caused by the above-mentioned. As a result, malfunctions of the electronic components and measuring instruments can be prevented, and the arc welding device 70 can be operated stably. In addition, by inputting the power supply voltage output from the control power supply 21 to the input coil of the second transformer 31, the voltage across the output coil of the second transformer 31 can be stabilized. As a result, when the charging switch 32 is turned on, the amount of charge stored in the charging unit 33 and therefore the current flowing through the coupling coil 35 can be kept constant, and the high frequency voltage V ＲＦ The voltage peak value V Ｐ This can suppress fluctuations.

[0096] <Modification 2> FIG. 11 is a schematic diagram of an arc welding device according to Modification 2. As shown in FIG.

[0097] Welding power supply 40 of this modified example shown in Figure 11 differs from welding power supply 40 of Embodiment 1 shown in Figure 1 in that control power supply 21 is omitted. Welding power supply 40 shown in Figure 11 also differs from welding power supply 40 shown in Figure 1 in that high-frequency generating circuit 30 includes rectifier 36 connected in parallel to the input coil of second transformer 31. Rectifier 36 also receives the voltage across the input coil of first transformer 13 in main circuit 10. That is, the voltage rectified by primary rectifier 11 is input to rectifier 36 via inverter 12. Furthermore, the voltage rectified by rectifier 36 is input to the input coil of second transformer 31 instead of the power supply voltage.

[0098] As described above, the inverter unit 12 generates the torch signal S ＴＳ Since the rectifier 36 operates in conjunction with the torch signal S ＴＳ Therefore, according to this modification, the voltage is applied from the main circuit 10 only while the torch signal S ＴＳ is in the on state, in other words, the high frequency voltage V ＲＦ Therefore, the high frequency generating circuit 30 can be driven only during the period when the high frequency generating circuit 30 can generate the high frequency signal.

[0099] Furthermore, the voltage across the input coil of the first transformer 13 is rectified and input to the input coil of the second transformer 31. In this modification, by changing the turn ratio of the second transformer 31, it is possible to obtain a high-frequency voltage V ＲＦ Specifically, in this modification, the turns ratio of the second transformer 31 is set smaller than those in the first embodiment and the first modification.

[0100] According to this modification, the control power supply 21 can be omitted, thereby reducing the cost of the control unit 20 and, in turn, the cost of the arc welding device 70. Furthermore, because the voltage on the input side of the second transformer 31 is higher than the control power supply voltage (generally DC 24 V or DC 15 V), the current flowing on the input side of the second transformer 31 is reduced. This allows not only the turns ratio of the second transformer 31 itself but also the number of turns itself to be reduced, thereby enabling the second transformer 31 to be made smaller and less expensive. Furthermore, the current capacity of the components arranged on the input side of the second transformer 31 may be small, thereby reducing the cost of these components.

[0101] Furthermore, according to this modification, it is possible to achieve the same effect as that achieved by the configuration shown in the first embodiment. That is, at the time of arc start, the high frequency voltage V ＲＦ As a result, malfunctions of the electronic components and measuring instruments described above can be prevented, and the arc welding device 70 can be operated stably.

[0102] <Modification 3> FIG. 12 is a schematic diagram of an arc welding device according to Modification 3. In FIG.

[0103] Welding power supply 40 of this modified example shown in FIG. 12 differs from welding power supply 40 of modified example 2 shown in FIG. 11 in that the voltage across the output coil of first transformer 13 of main circuit 10 is input to rectifier 36 of high-frequency generating circuit 30.

[0104] In the configuration shown in Modification 2, the voltage across the input coil of the first transformer 13 is rectified and input to the input coil of the second transformer 31, so the dielectric strength voltage of the high-frequency generating circuit 30 needs to be increased, which leads to an increase in the cost of the high-frequency generating circuit 30.

[0105] On the other hand, according to this modification, the high frequency generating circuit 30 may have a low dielectric strength voltage. In other words, the cost of the high frequency generating circuit 30 can be reduced. In this modification, as in the second modification, by changing the turns ratio of the second transformer 31, it is possible to generate a high frequency voltage V of the same order as in the first embodiment and the first modification. ＲＦ This is causing the problem.

[0106] Furthermore, according to this modification, it is possible to achieve the same effect as that achieved by the configuration shown in the first embodiment. That is, at the time of arc start, the high frequency voltage V ＲＦ As a result, malfunctions of the electronic components and measuring instruments described above can be prevented, and the arc welding device 70 can be operated stably.

[0107] Other Embodiments New embodiments can be created by appropriately combining the components shown in Embodiments 1 to 4 and Modifications 1 to 3. For example, welding power supply 40 shown in Modifications 1 to 3 can be applied to arc welding apparatus 70 shown in Embodiments 2 to 4, respectively.

[0108] The welding power supply of the present disclosure is useful because it can reduce high-frequency noise when an arc starts.

[0109] REFERENCE SIGNS LIST 10 Main circuit 11 Primary side rectifier 12 Inverter section 13 First transformer 14 Secondary side rectifier 15 Welding current detector 16 Welding voltage detector 20 Control section 21 Control power supply 22 Control processor 23 Input section 30 High frequency generating circuit 31 Second transformer 32 Charging switch 33 Charging section 34 Discharge switch 35 Coupling coil 36 Rectifier section 37 Circuit board 40 Welding power supply device 50 Welding torch 51 Torch switch 52 Electrode 61 First power cable 62 Second power cable 63 Torch switch cable 70 Arc welding device 80 Base material 90 Three-phase AC power supply

Claims

1. A welding power supply used in non-consumable electrode arc welding, comprising at least a main circuit, a high frequency generating circuit, and a control unit, wherein the main circuit is electrically connected to an electrode provided on a welding torch and supplies welding output to the electrode, the high frequency generating circuit has at least a charging unit, and a charge switch and a discharge switch, each electrically connected to the charging unit, and while a torch signal of a torch switch provided on the welding torch is in an on state, the control unit operates the high frequency generating circuit in a first mode, and in the first mode, the control unit: activates the charging switch to charge the charging unit, stops the charging switch after a predetermined charging time has elapsed since charging of the charging unit started, activates the discharge switch after stopping the charging switch to discharge the charging unit, and stops the discharge switch after a predetermined discharging time has elapsed since discharging of the charging unit started, and by discharging the charging unit, the high frequency generating circuit generates a high frequency voltage having a predetermined voltage peak value between the base metal and the electrode only once.

2. A welding power supply according to claim 1, wherein the charging time is set in the control unit, and the voltage peak value is reduced by shortening the charging time.

3. A welding power supply used in non-consumable electrode arc welding, comprising at least a main circuit, a high frequency generating circuit, and a control unit, wherein the main circuit is electrically connected to an electrode provided on a welding torch and supplies welding output to the electrode, the high frequency generating circuit has at least a charging unit, and a charging switch and a discharging switch each electrically connected to the charging unit, wherein a signal stop time from the end of discharging of the charging unit to the start of the next charging is set in the control unit, and while the torch signal of the torch switch provided on the welding torch is in an on state, the control unit operates the high frequency generating circuit in a second mode, and in the second mode the control unit: activates the charging switch to charge the charging unit, deactivates the charging switch after a predetermined charging time has elapsed since charging of the charging unit started, activates the discharge switch after deactivating the charging switch to discharge the charging unit, and deactivates the discharge switch after a predetermined discharge time has elapsed since discharging of the charging unit started, and by discharging the charging unit, the high frequency generating circuit generates a high frequency voltage having a predetermined voltage peak value between the base metal and the electrode, and after the signal stop time has elapsed since the discharge switch was stopped, the charge switch is started again to charge the charging unit, and until the control unit detects that an arc has occurred between the base metal and the electrode or the torch signal of the torch switch is turned off, the high-frequency generating circuit repeatedly generates the high-frequency voltage between the base metal and the electrode at a predetermined cycle.

4. A welding power supply according to claim 3, wherein the charging time is set in the control unit, and the voltage peak value is reduced by shortening the charging time.

5. A welding power supply according to claim 1, wherein a signal stop time from the end of discharging of the charging unit to the start of the next charging is set in the control unit, and while a torch signal from a torch switch provided on the welding torch is in an on state, the control unit is configured to be able to switch between operating the high frequency generation circuit in the first mode and operating the high frequency generation circuit in the second mode, and the control unit in the second mode: activates the charging switch to charge the charging unit, stops the charging switch after a predetermined charging time has elapsed since charging of the charging unit started, activates the discharge switch to discharge the charging unit after charging of the charging unit is completed, and stops the discharge switch after a predetermined discharge time has elapsed since discharging of the charging unit started, and by discharging the charging unit, the high frequency generation circuit generates the high frequency voltage having the voltage peak value between the base metal and the electrode, and after the signal stop time has elapsed since the discharge switch was stopped, activates the charging switch again to charge the charging unit, a control unit that repeatedly executes a series of operations from activating the charging switch to deactivating the discharging switch until an arc is detected between the base metal and the electrode or the torch signal of the torch switch is turned off, thereby causing the high-frequency generating circuit to repeatedly generate the high-frequency voltage between the base metal and the electrode at a predetermined cycle.

6. A welding power supply according to claim 1, characterized in that the high frequency generating circuit further comprises a second transformer and a coupling coil, the charging section is connected in parallel to the output coil of the second transformer, the input coil of the coupling coil is connected to the charging section and the discharge switch, and the output coil of the coupling coil is connected to the secondary rectifier section of the main circuit and the base material.

7. A welding power supply according to claim 6, wherein the control unit has a control power supply connected to an external power supply, the control power supply converts AC voltage input from the external power supply into a power supply voltage, and the power supply voltage is input to the input coil of the second transformer.

8. A welding power supply according to claim 7, characterized in that the charging switch is disposed between the output coil of the second transformer and the charging unit, and is electrically connected to the output coil and the charging unit.

9. A welding power supply according to claim 7, characterized in that the charging switch is disposed between the control power supply and the input coil of the second transformer, and is electrically connected to the control power supply and the input coil.

10. A welding power supply according to claim 6, characterized in that the charging switch is provided between a rectifier provided in the high frequency generating circuit and the input coil of the second transformer, and is electrically connected to the rectifier and the input coil.

11. A welding power supply according to claim 6, wherein the main circuit has at least a primary side rectifier that rectifies an AC voltage input from an external power source, an inverter that converts a first DC voltage rectified by the primary side rectifier into an AC voltage, a first transformer that transforms the AC voltage output from the inverter, and a secondary side rectifier that converts the AC voltage transformed by the first transformer into a second DC voltage.

12. A welding power supply according to claim 11, wherein the high frequency generating circuit has a rectifier connected in parallel to the input coil of the second transformer, and the voltage across the input coil of the first transformer is input to the rectifier.

13. A welding power supply according to claim 11, wherein the high frequency generating circuit has a rectifier connected in parallel to the input coil of the second transformer, and the voltage across the output coil of the first transformer is input to the rectifier.

14. An arc welding device comprising at least the welding power supply device according to any one of claims 1 to 13, and a welding torch connected to the welding power supply device, wherein the welding torch is provided with a torch switch that generates the torch signal, and the control unit operates the high frequency generating circuit by operating the torch switch.

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