Arc welding device

Abstract

This arc welding device comprises a welding power supply device and a welding torch that holds a non-consumable electrode. The welding power supply device has a main circuit and a high frequency generation circuit. The main circuit is electrically connected to the electrode and supplies a welding output to the electrode. The high frequency generation circuit has a charging unit, discharge switches, and a coupling coil. The high frequency generation circuit discharges the charging unit and generates high frequency voltage between a base material and the electrode. A voltage induced in an output-side coil by a current flowing from the charging unit to a first input-side coil by the activation of a first discharge switch and a voltage induced in the output-side coil by a current flowing from the charging unit to a second input-side coil by the activation of a second discharge switch have polarities reverse of each other.

Description

Arc welding equipment

[0001] The present disclosure relates to arc welding devices.

[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] The electric discharge machining system disclosed in Patent Document 1 includes a machining torch, an electric discharge machining power supply device, and a high frequency generator, and discharges electricity in a spark gap connected to the capacitor by charging and discharging a capacitor provided in the high frequency generating circuit.

[0004] When a discharge occurs in the spark gap, a high-frequency voltage is generated between the base material connected to the coupling coil and the electrode of the processing torch via the 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.

[0005] Patent No. 6260007

[0006] However, due to various reasons, such as the need to match the polarity of the welding voltage from the main circuit, there is a demand for the ability to arbitrarily switch the polarity of the high-frequency voltage generated between the base material and the electrode in the high-frequency generating circuit. However, in conventional non-consumable electrode arc welding equipment, because a spark gap is used, the polarity of the high-frequency voltage generated between the base material and the electrode is fixed in one direction and cannot be changed.

[0007] An object of the present disclosure is to arbitrarily switch the polarity of the high frequency voltage generated between the base metal and the electrode in a non-consumable electrode arc welding device.

[0008] An arc welding apparatus according to the present disclosure includes a welding power supply and a welding torch holding a non-consumable electrode, the welding power supply having a main circuit and a high frequency generating circuit, the main circuit being electrically connected to the electrode and supplying a welding output to the electrode, the high frequency generating circuit having a charging unit, a discharge switch electrically connected to the charging unit, and a coupling coil having an input side coil electrically connected to the charging unit and the discharge switch and an output side coil electrically connected to the main circuit, and the high frequency generating circuit generating a high frequency voltage between a base metal and the electrode by discharging the charging unit. the discharge switch includes a first discharge switch and a second discharge switch electrically connected in parallel to each other, the input side coil includes a first input side coil electrically connected to the charging unit and the first discharge switch and a second input side coil electrically connected to the charging unit and the second discharge switch, and a voltage induced in the output side coil by a current flowing from the charging unit to the first input side coil when the first discharge switch is activated and a voltage induced in the output side coil by a current flowing from the charging unit to the second input side coil when the second discharge switch is activated have mutually opposite polarities.

[0009] According to the present disclosure, in a non-consumable electrode arc welding device, the polarity of the high frequency voltage generated between the base material and the electrode can be switched as desired.

[0010] FIG. 1 shows a schematic configuration of an arc welding apparatus according to a first embodiment. FIG. 2 shows a control block diagram of the arc welding apparatus according to the first embodiment. FIG. 3 shows an enlarged view of a charging unit, a discharge switch, and a coupling coil according to the first embodiment. FIG. 4 shows a control flowchart according to the first embodiment. FIG. 5 shows the concept of switching the charge switch and the discharge switch according to the first embodiment. FIG. 6 is a diagram corresponding to FIG. 3 according to a second embodiment. FIG. 7 is a diagram corresponding to FIG. 3 according to a third embodiment. FIG. 8 is a diagram corresponding to FIG. 1 according to a fourth embodiment.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 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.

[0012] First Embodiment (Arc Welding Apparatus) An arc welding apparatus 70 according to a first embodiment will be described. Fig. 1 shows a schematic configuration of the arc welding apparatus 70. Fig. 2 shows a control block of the arc welding apparatus 70. The arc welding apparatus 70 is a non-consumable electrode arc welding apparatus. Specifically, the arc welding apparatus 70 performs TIG (Tungsten Inert Gas) welding.

[0013] 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 .

[0014] 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 type. Welding torch 50 holds non-consumable electrode 52.

[0015] 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.

[0016] Torch switch cable 63 electrically connects control unit 20 of welding power supply 40 and torch switch 51 provided on welding torch 50 .

[0017] First power cable 61 and torch switch cable 63 may be combined into a single composite cable. Also, a gas pipe (not shown) for supplying shielding gas to welding torch 50 may be connected. In this case, the gas pipe may be combined into the composite cable.

[0018] The welding power supply 40 includes a main circuit 10 , a control unit 20 , and a high frequency generating circuit 30 .

[0019] Main circuit 10 is electrically connected to electrode 52 provided on welding torch 50. Main circuit 10 supplies welding output to electrode 52. Main circuit 10 has primary side rectifier 11, inverter 12, first transformer 13, secondary side rectifier 14, welding current detector 15, and welding voltage detector 16.

[0020] Primary side rectifier 11 is configured with, for example, a diode and a capacitor, and rectifies the AC voltage input to welding power supply 40 from three-phase AC power supply 90, which serves as an external power supply, into a first DC voltage.

[0021] The inverter unit 12 is composed of a plurality of switching elements, such as 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 the switching elements. The inverter unit 12 operates in conjunction with a torch signal STS generated by operating a torch switch 51.

[0022] The first transformer 13 transforms the AC voltage output from the inverter unit 12 .

[0023] The secondary side rectifier 14 has the same configuration as the primary side rectifier 11, and rectifies the AC voltage output from the first transformer 13 into a second DC voltage.

[0024] The welding current detection unit 15 detects the welding current flowing through the electrode 52 .

[0025] The welding voltage detection unit 16 detects the welding voltage between the base material 80 and the electrode 52 .

[0026] 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 include other functional blocks.

[0027] The control power supply 21 is electrically connected to a three-phase AC power supply 90 serving as an external power supply. Two phase-to-phase voltages of the three-phase AC power supply 90 are input to the control power supply 21. The control power supply 21 is electrically connected to both ends of the second transformer input coil 31 a of the second transformer 31 in the high-frequency generating circuit 30. More specifically, the control power supply 21 is connected to one end of the input coil 31 a of the second transformer 31 via a charging switch 32, and is also directly connected to the other end of the input coil 31 a of the second transformer 31.

[0028] 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. When the charging switch 32 is activated, the control power supply 21 inputs the AC voltage to the second transformer input coil 31a of the second transformer 31. The control power supply 21 converts the AC voltage input from a three-phase AC power supply (external power supply) 90 into a power supply voltage. When the charging switch 32 is activated, the power supply voltage is input to the second transformer input coil 31a of the second transformer 31. When a current flows through the input coil 31a of the second transformer 31, a current is excited in the output coil 31b of the second transformer 31, and an electric charge is stored in the charging unit 33 (capacitor).

[0029] In this embodiment, the power supply voltage output from control power supply 21 is +24 V, but is not limited to this. Input unit 23 is configured with an input device such as a keyboard, touch panel, or rotary switch. Welding conditions are set by operating input unit 23. Input unit 23 may be configured to be able to communicate with control unit 20 and may be provided external to welding power supply 40.

[0030] The control processor 22 is composed of one or more central processing units (CPUs). The CPU has a memory area (not shown) composed of a read-only memory (ROM), a random access memory (RAM), etc. The control processor 22 may have components other than a CPU. The control processor 22 receives the torch signal STS. When the torch signal STS is turned on, the control processor 22 sends a drive signal to the inverter unit 12. The inverter unit 12 receives the drive signal and operates to convert the first DC voltage into an AC voltage. When the torch signal STS is turned on, the control processor 22 sends a drive signal to the high-frequency generating circuit 30. The high-frequency generating circuit 30 receives the drive signal and operates.

[0031] 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 and arranged on the same circuit board 37.

[0032] The second transformer input coil 31a of the second transformer 31 is electrically connected to the control power supply 21. More specifically, one end of the input coil 31a of the second transformer 31 is connected to the control power supply 21 via a charging switch 32. The other end of the input coil 31a of the second transformer 31 is directly connected to the control power supply 21. The second transformer 31 transforms the power supply voltage input from the control power supply 21.

[0033] The charging switch 32 is electrically connected to the control power supply 21. The charging switch 32 is electrically connected to the input coil 31a of the second transformer 31. The charging switch 32 is electrically connected in series to the charging unit 33 via the input coil 31a and output coil 31b of the second transformer 31. The charging switch 32 is composed of a semiconductor switching element such as a MOSFET, an IGBT, or a bipolar transistor. It is preferable that the charging switch 32 has a fast response to an input signal, a small on-resistance, and is capable of passing a large current.

[0034] The charging unit 33 is configured by, for example, a capacitor having a predetermined capacitance, and is electrically connected in parallel to the second transformer output coil 31 b of the second transformer 31 .

[0035] The discharge switch 34 is electrically connected in series to the charging unit 33 and the coupling coil 35. The discharge switch 34 is configured, for example, by a semiconductor switching element such as a MOSFET, an IGBT, or a bipolar transistor, similar to the charge switch 32. It is preferable that the discharge switch 34 has a large time change in the current flowing therethrough, i.e., a large di / dt, and is capable of instantaneously passing a large current.

[0036] As will be described in detail later, the discharge switch 34 includes a first discharge switch 34a and a second discharge switch 34b.

[0037] The coupling coil 35 is a type of transformer. The coupling coil 35 has input coils 35a, 35b and an output coil 35c. The input coils 35a, 35b are electrically connected to the charging unit 33 and the discharge switch 34. The output coil 35c is electrically connected to the main circuit 10. Specifically, the output coil 35c is electrically connected to the secondary rectifier 14 of the main circuit 10 and the base material 80.

[0038] One end of each of the input coils 35a and 35b of the coupling coil 35 is electrically connected to the charging unit 33 via the discharge switch 34. The other end of each of the input coils 35a and 35b of the coupling coil 35 is electrically connected to the charging unit 33. The input coils 35a and 35b of the coupling coil 35 are electrically connected to the charging unit 33 and the discharge switch 34.

[0039] As will be described in detail later, the input coils 35a, 35b include a first input coil 35a and a second input coil 35b.

[0040] The output coil 35c of the coupling coil 35 is electrically connected in series to the second power cable 62. The output coil 35c of the coupling coil 35 is electrically connected to the secondary rectifier 14 of the main circuit 10 and the base material 80.

[0041] When the discharge switch 34 is activated, the charge accumulated in the charging unit 33 is discharged. When a current flows through the input coils 35a and 35b of the coupling coil 35 based on this charge, a voltage is induced in the output coil 35c of the coupling coil 35. Since the time during which the current flows through the input coils 35a and 35b of the coupling coil 35 is approximately several microseconds to several tens of microseconds, a voltage with a frequency of several hundred kHz to 1 MHz or more is induced in the output coil 35c of the coupling coil 35. This voltage is applied to the base material 80, generating a voltage of approximately the same frequency between the base material 80 and the electrode 52.

[0042] The operation of the arc welding device 70 will now be briefly described.

[0043] When the torch switch 51 is operated to turn on the torch signal STS while the welding power supply 40 is electrically connected to the three-phase AC power supply 90, the torch signal STS is input to the control processor 22 via the torch switch cable 63. The control processor 22, upon receiving the torch signal STS, operates the inverter unit 12 of the main circuit 10 at a predetermined cycle. This causes a current to flow intermittently through the input coil of the first transformer 13, inducing a periodically fluctuating voltage in the output coil of the first transformer 13. The voltage induced in the output coil of the first transformer 13 is rectified by the secondary-side rectifier 14. The rectified second DC voltage is applied between the electrode 52 electrically connected to the first power cable 61 and the workpiece 80 electrically connected to the second power cable 62.

[0044] In the following description, the voltage generated between the base material 80 and the electrode 52 by the discharge from the charging section 33 will be referred to as the high frequency voltage VRF.

[0045] Furthermore, upon receiving the torch signal STS, the control processor 22 opens and closes the charge switch 32 and the discharge switch 34 at predetermined timings, respectively. This charges the charging unit 33, and after charging stops, the discharge switch 34 discharges the charge from the charging unit 33. This applies the above-mentioned high-frequency voltage VRF between the base material 80 and the electrode 52, generating a micro-arc ARC.

[0046] The high frequency generating circuit 30 discharges the charging unit 33 to generate a high frequency voltage VRF between the base material 80 and the electrode 52. The high frequency generating circuit 30 then generates a micro-arc ARC between the base material 80 and the electrode 52.

[0047] In addition, a small arc ARC is generated between the base material 80 and the electrode 52 by the high-frequency generating circuit 30, and an arc corresponding to the second DC voltage from the main circuit 10 is generated between the base material 80 and the electrode 52, and the base material 80 is welded by the heat input from the arc.

[0048] (Polarity Switching) The following describes the switching of the polarity of the high-frequency voltage VRF generated between the base material 80 and the electrode 52. Fig. 3 shows an enlarged view of the charging unit 33, the discharge switch 34, and the coupling coil 35. The upper view of Fig. 3 shows a first state M1, which will be described later, and the lower view of Fig. 3 shows a second state M2, which will be described later.

[0049] As described above, the discharge switch 34 includes the first discharge switch 34a and the second discharge switch 34b. The first discharge switch 34a and the second discharge switch 34b are electrically connected in parallel to each other. The first discharge switch 34a is electrically connected to the charging unit 33 and a first input coil 35a (described later). The second discharge switch 34b is electrically connected to the charging unit 33 and a second input coil 35b (described later).

[0050] As described above, the input coils 35a, 35b of the coupling coil 35 include the first input coil 35a and the second input coil 35b. The first input coil 35a and the second input coil 35b are electrically connected in parallel to each other. The first input coil 35a is electrically connected to the charging unit 33 and the first discharge switch 34a. The second input coil 35b is electrically connected to the charging unit 33 and the second discharge switch 34b.

[0051] The first input coil 35a and the second input coil 35b are arranged with opposite polarities (see polarity marks).

[0052] In the coupling coil 35, the output coil 35c is configured as one coil corresponding to both the first input coil 35a and the second input coil 35b.

[0053] The first voltage Va induced in the output coil 35c by the first current Ia flowing from the charging unit 33 to the first input coil 35a when the first discharge switch 34a is activated, and the second voltage Vb induced in the output coil 35c by the second current Ib flowing from the charging unit 33 to the second input coil 35b when the second discharge switch 34b is activated, have opposite polarities to each other.

[0054] The first voltage Va and the second voltage Vb have opposite polarities. The first current Ia and the second current Ib flow in the same direction, from positive to negative. Because the first input coil 35a and the second input coil 35b are arranged with opposite polarities, the first voltage Va induced in the output coil 35c by the first current Ia flowing through the first input coil 35a and the second voltage Vb induced in the output coil 35c by the second current Ib flowing through the second input coil 35b have opposite polarities.

[0055] (Switch Control) The following describes the control of the charge switch 32 and the discharge switch 34 by the control unit 20. The control processor 22 of the control unit 20 controls the activation and deactivation of the charge switch 32 and the activation and deactivation of the discharge switch 34.

[0056] Activating the charge switch 32 (discharge switch 34) means switching (repeatedly turning on and off) the charge switch 32 (discharge switch 34). Stopping the charge switch 32 (discharge switch 34) means not switching the charge switch 32 (discharge switch 34).

[0057] The control processor 22 of the control unit 20 outputs a charging signal SCG to the charging switch 32 to activate the charging switch 32. When the charging switch 32 is activated, the charging unit 33 is charged.

[0058] The control processor 22 of the control unit 20 outputs a first discharge signal SDCG1 to the first discharge switch 34a or a second discharge signal SDCG2 to the second discharge switch 34b to activate the first discharge switch 34a or the second discharge switch 34b. When the first discharge switch 34a or the second discharge switch 34b is activated, the charging unit 33 is discharged.

[0059] The control processor 22 of the control unit 20 switches between the first state M1 and the second state M2.

[0060] In the first state M1, the control unit 20 activates the first discharge switch 34a and deactivates the second discharge switch 34b. In the first state M1, a first current Ia flows through the first input coil 35a, and a first voltage Va is induced in the output coil 35c.

[0061] In the second state M2, the control unit 20 activates the second discharge switch 34b and deactivates the first discharge switch 34a. In the second state M2, a second current Ib flows through the second input coil 35b, and a second voltage Vb is induced in the output coil 35c.

[0062] (Flowchart) Figure 4 shows a control flowchart. Starting from the start, in a first step S1, the control unit 20 selects either the first state M1 or the second state M2 (first state M1 OR second state M2?). If the first state M1 is selected, the process proceeds to a second step S2. If the second state M2 is selected, the process proceeds to a third step S3.

[0063] In the second step S2, the control unit 20 executes the first state M1, outputs the first discharge signal SDCG1 to the first discharge switch 34a to activate the first discharge switch 34a, and stops the second discharge switch 34b without outputting the second discharge signal SDCG2 to the second discharge switch 34b. As a result, the first current Ia flows through the first input coil 35a, and the first voltage Va is induced in the output coil 35c. Then, the process reaches the end.

[0064] In the third step S3, the control unit 20 executes the second state M2, outputs the second discharge signal SDCG2 to the second discharge switch 34b to activate the second discharge switch 34b, and stops the first discharge switch 34a without outputting the first discharge signal SDCG1 to the first discharge switch 34a. As a result, the second current Ib flows through the second input coil 35b, and the second voltage Vb is induced in the output coil 35c. Then, the process reaches the end.

[0065] (Switching) Fig. 5 shows the concept of switching the charge switch 32 and the discharge switch 34. As shown in the upper diagram of Fig. 5, the control unit 20 (control processor 22) may activate (switch) the charge switch 32 (discharge switch 34) via the PWM unit 110. In this case, the control unit 20 sends a simple pulse signal SP1 to the PWM unit 110. Upon receiving the simple pulse signal SP1, the PWM unit 110 sends a switching signal SP2 to the charge switch 32 (discharge switch 34). The switching signal SP2 is repeatedly turned on and off.

[0066] 5, the control unit 20 (control processor 22) may activate (switch) the charge switch 32 (discharge switch 34) directly without going through the PWM unit 110. In this case, the control unit 20 sends a switching signal SP2 (repeated on / off) directly to the charge switch 32 (discharge switch 34).

[0067] PWM is an abbreviation for Pulse Width Modulation. The PWM unit 110 controls the voltage and current by changing the period and duty ratio of the periodic pulse wave generated. (Function and Effect) A first voltage Va is induced in the output coil 35c by a first current Ia flowing from the charging unit 33 to the first input coil 35a when the first discharge switch 34a is activated, and a second voltage Vb is induced in the output coil 35c by a second current Ib flowing from the charging unit 33 to the second input coil 35b when the second discharge switch 34b is activated. These voltages have opposite polarities.

[0068] The polarity of the high frequency voltage VRF generated between the base material 80 and the electrode 52 can be arbitrarily switched by selecting either the first discharge switch 34a or the second discharge switch 34b.

[0069] In the non-consumable electrode arc welding device 70, the polarity of the high frequency voltage VRF generated between the base material 80 and the electrode 52 can be switched as desired.

[0070] This is effective when it is desired to match the polarity of the high frequency voltage VRF from the high frequency generating circuit 30 with the polarity of the welding voltage from the main circuit 10.

[0071] The control unit 20 switches between a first state M1 in which the first discharge switch 34 a is activated and the second discharge switch 34 b is deactivated, and a second state M2 in which the second discharge switch 34 b is activated and the first discharge switch 34 a is deactivated. This makes it easy to switch the polarity of the high frequency voltage VRF.

[0072] In the coupling coil 35, the output coil 35c is configured as a single coil corresponding to both the first input coil 35a and the second input coil 35b, which simplifies the configuration of the output coil 35c.

[0073] Second Embodiment An arc welding apparatus 70 according to a second embodiment will be described. In the following description, the same components as those in the above embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted. Fig. 6 is a view equivalent to Fig. 3 .

[0074] In the coupling coil 35, the output side coil 35c is composed of a split coil including a first output side coil 35d corresponding to the first input side coil 35a and a second output side coil 35e corresponding to the second input side coil 35b.

[0075] The other configurations are the same as those of the first embodiment.

[0076] Third Embodiment An arc welding apparatus 70 according to a third embodiment will be described. In the following description, the same components as those in the above-described embodiment will be denoted by the same reference numerals, and detailed description thereof will be omitted. Fig. 7 is a view equivalent to Fig. 3 .

[0077] A resistor 38 and a capacitor 39 are electrically connected in parallel to the first discharge switch 34a and the second discharge switch 34b, respectively.

[0078] The other configurations are the same as those of the first and second embodiments.

[0079] This can mitigate the occurrence of surge voltage in the switch that is turned off, either the first discharge switch 34a or the second discharge switch 34b.

[0080] Fourth Embodiment An arc welding apparatus 70 according to a fourth embodiment will be described. In the following description, the same components as those in the above-described embodiments will be denoted by the same reference numerals, and detailed description thereof will be omitted. Fig. 8 is a view equivalent to Fig. 1 .

[0081] A voltage is input to a second transformer input coil 31a of a second transformer 31 in the high frequency generating circuit 30 from a high frequency generating power supply (second power supply) 100 that is separate from the three-phase AC power supply (first power supply) 90 used in the main circuit 10 and has a lower voltage than the three-phase AC power supply (first power supply) 90. The high frequency generating power supply (second power supply) 100 is, for example, a +24V DC power supply.

[0082] The high frequency generating power supply (second power supply) 100 is connected to one end of the input side coil 31 a of the second transformer 31 via the charging switch 32, and is also directly connected to the other end of the input side coil 31 a of the second transformer 31.

[0083] The other configurations are the same as those of the first to third embodiments.

[0084] <Other Embodiments> Although the present disclosure has been described above with reference to preferred embodiments, these descriptions are not limiting, and it goes without saying that various modifications, substitutions, and combinations are possible.

[0085] The discharge switch 34 may be a relay switch as long as it can be controlled by the control unit 20 .

[0086] The present disclosure is applicable to arc welding devices and is therefore extremely useful and has high industrial applicability.

[0087] 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 31a Second transformer input coil 31b Second transformer output coil 32 Charging switch 33 Charging section 34 Discharge switch 34a First discharge switch 34b Second discharge switch 35 Coupling coil 35a First input coil (input coil) 35b Second input coil (input coil) 35c Output coil 35d First output coil 35e Second output coil 37 Circuit board 38 Resistor 39 Capacitor 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 (external power supply, first power supply) 100 High frequency generating power supply (second power supply) 110 PWM section STS Torch signal SCG Charging signal SDCG1 First discharge signal SDCG2 Second discharge signal SP1 Pulse signal SP2 Switching signal VRF High frequency voltage ARC Micro arc Ia First current (current) Ib Second current (current) Va First voltage (voltage) Vb Second voltage (voltage) M1 First state M2 Second state

Claims

1. A welding power supply comprising: a welding torch holding a non-consumable electrode; the welding power supply having a main circuit; and a high frequency generating circuit; the main circuit is electrically connected to the electrode and supplies a welding output to the electrode; the high frequency generating circuit having: a charging unit; a discharge switch electrically connected to the charging unit; and a coupling coil having an input side coil electrically connected to the charging unit and the discharge switch and an output side coil electrically connected to the main circuit; the high frequency generating circuit generates a high frequency voltage between the base metal and the electrode by discharging the charging unit; the discharge switch includes a first discharge switch and a second discharge switch electrically connected to each other in parallel; the input side coil includes a first input side coil electrically connected to the charging unit and the first discharge switch, and a second input side coil electrically connected to the charging unit and the second discharge switch; an arc welding device in which a voltage induced in the output side coil by a current flowing from the charging unit to the first input side coil when the first discharge switch is activated and a voltage induced in the output side coil by a current flowing from the charging unit to the second input side coil when the second discharge switch is activated have opposite polarities.

2. An arc welding device as described in claim 1, further comprising a control unit, which switches between a first state in which the first discharge switch is activated and the second discharge switch is deactivated, and a second state in which the second discharge switch is activated and the first discharge switch is deactivated.

3. The arc welding device according to claim 1 or 2, wherein a resistor and a capacitor are electrically connected in parallel to the first discharge switch and the second discharge switch, respectively.

4. An arc welding device according to claim 1 or 2, wherein the output coil is configured as a single coil corresponding to both the first input coil and the second input coil.

5. An arc welding device as described in claim 1 or 2, wherein the output coil is composed of a split coil including a first output coil corresponding to the first input coil and a second output coil corresponding to the second input coil.

6. An arc welding device according to claim 1 or 2, wherein the output coil is electrically connected to the secondary rectifier of the main circuit and the base material.

7. An arc welding device according to claim 1 or 2, wherein the high frequency generating circuit has a second transformer, and the charging unit is electrically connected in parallel to a second transformer output coil of the second transformer.

8. The arc welding device according to claim 7, further comprising a control unit, the control unit having a control power supply electrically connected to an external power supply, the control power supply converting an AC voltage input from the external power supply into a power supply voltage, and the power supply voltage being input to a second transformer input side coil of the second transformer.

9. An arc welding device as described in claim 7, wherein a voltage is input to the second transformer input coil of the second transformer from a second power source that is separate from the first power source used in the main circuit and has a lower voltage than the first power source.

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