WO2018186098A1 - Shielded metal arc welding system and welding power supply device for shielded metal arc welding - Google Patents

Shielded metal arc welding system and welding power supply device for shielded metal arc welding Download PDF

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Publication number
WO2018186098A1
WO2018186098A1 PCT/JP2018/008772 JP2018008772W WO2018186098A1 WO 2018186098 A1 WO2018186098 A1 WO 2018186098A1 JP 2018008772 W JP2018008772 W JP 2018008772W WO 2018186098 A1 WO2018186098 A1 WO 2018186098A1
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Prior art keywords
circuit
arc welding
voltage
output
current
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PCT/JP2018/008772
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French (fr)
Japanese (ja)
Inventor
雄一 宮島
陽彦 真鍋
賢人 高田
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株式会社ダイヘン
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Publication of WO2018186098A1 publication Critical patent/WO2018186098A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/06—Arrangements or circuits for starting the arc, e.g. by generating ignition voltage, or for stabilising the arc
    • B23K9/073—Stabilising the arc

Definitions

  • the present disclosure relates to a coated arc welding system and a welding power supply device for coated arc welding.
  • Covered arc welding is known as welding suitable for outdoor work.
  • an arc is generated between a covered arc welding rod and a workpiece, and welding is performed by the heat of the arc.
  • covered arc welding unlike carbon dioxide arc welding, there is no need to spray gas. Therefore, welding work can be performed with a simple device. Also, welding work can be performed outdoors where gas is scattered by the wind.
  • FIG. 7 is a diagram showing an example of a coated arc welding system according to a comparative example (note that the system shown in FIG. 7 is not necessarily publicly known).
  • the coated arc welding system shown in FIG. 7 includes a coated arc welding rod B, a welding rod holder C for holding the coated arc welding rod B and energizing a welding current, and a coated arc welding rod via the welding rod holder C.
  • a welding power supply device A100 that supplies electric power to B.
  • the welding power supply device A100 includes a transformer 300 that transforms AC power, inputs AC power from the commercial power source D to the primary side of the transformer 300, and outputs AC power after transformation from the secondary side of the transformer 300. .
  • One output terminal a of the welding power source device A100 is connected to the workpiece W by a cable, and the other output terminal b is connected to the welding rod holder C by a cable.
  • the welding power source device A100 generates an arc between the tip of the coated arc welding rod B and the workpiece W, and supplies electric power.
  • the transformer 300 is increased in size, which hinders the welding power supply device A100 from being reduced in size and weight.
  • an object thereof is to provide a more suitable coated arc welding system.
  • an object of the present disclosure is to provide a coated arc welding system that suppresses arc breakage when the polarity of the output current changes and that can reduce the size and weight of the welding power supply device.
  • a coated arc welding system contains a covering arc welding rod and the welding power supply device which supplies electric power to the said covering arc welding rod.
  • the welding power supply device includes a rectifier circuit, a DC reactor, an inverter circuit, and a voltage superimposing circuit.
  • the rectifier circuit rectifies AC power.
  • the DC reactor smoothes the output of the rectifier circuit.
  • the inverter circuit converts DC power output from the DC reactor into AC power and outputs the AC power to the coated arc welding rod.
  • the voltage superimposing circuit superimposes a re-ignition voltage on the output to the coated arc welding rod.
  • the voltage superimposing circuit superimposes the re-ignition voltage when the polarity of the output current of the inverter circuit is switched.
  • a welding power supply device for covering arc welding.
  • the welding power supply device includes a rectifier circuit, a DC reactor, an inverter circuit, and a voltage superimposing circuit.
  • the rectifier circuit rectifies AC power.
  • the DC reactor smoothes the output of the rectifier circuit.
  • the inverter circuit converts DC power output from the DC reactor into AC power and outputs the AC power to the coated arc welding rod.
  • the voltage superimposing circuit superimposes a re-ignition voltage on the output to the coated arc welding rod.
  • the voltage superimposing circuit superimposes the re-ignition voltage when the polarity of the output current of the inverter circuit is switched.
  • FIG. 1 is a diagram showing an overall configuration of a coated arc welding system according to the first embodiment.
  • the coated arc welding system includes a welding power source device A ⁇ b> 1, a coated arc welding rod B, and a welding rod holder C.
  • the welding rod holder C is for an operator to hold and weld, and holds the covered arc welding rod B, and supplies the alternating current input from the welding power source device A1 to the covered arc welding rod B.
  • the welding power source device A1 converts AC power input from the commercial power source D and outputs it from the output terminals a and b.
  • One output terminal a is connected to the workpiece W by a cable.
  • the other output terminal b is connected to the welding rod holder C by a cable.
  • the welding power supply device A1 generates an arc between the tip of the covered arc welding rod B and the workpiece W to supply electric power. Welding is performed by the heat of the arc.
  • the welding power supply device A1 includes a rectifying / smoothing circuit 1, an inverter circuit 2, a transformer 3, a rectifying circuit 4, a DC reactor 5, a voltage superimposing circuit 6, an inverter circuit 7, a control circuit 8, a current sensor 91, and a voltage sensor 92. .
  • the rectifying / smoothing circuit 1 converts AC power input from the commercial power source D into DC power and outputs it.
  • the rectifying / smoothing circuit 1 includes a rectifying circuit for rectifying an alternating current and a smoothing capacitor for smoothing.
  • the inverter circuit 2 is, for example, a single-phase full-bridge type PWM control inverter and includes four switching elements.
  • the inverter circuit 2 converts the DC power input from the rectifying / smoothing circuit 1 into high-frequency power by switching the switching element according to the drive signal input from the control circuit 8, and outputs the high-frequency power.
  • the inverter circuit 2 only needs to convert DC power into AC power, and may be, for example, a half-bridge type or an inverter circuit having another configuration.
  • the transformer 3 transforms the high-frequency voltage output from the inverter circuit 2 and outputs it to the rectifier circuit 4. Since the transformer 3 is a high frequency transformer, it is smaller and lighter than a commercial frequency transformer.
  • the rectifier circuit 4 is, for example, a full-wave rectifier circuit, and rectifies high-frequency power input from the transformer 3 and outputs the rectified circuit to the inverter circuit 7.
  • the rectifier circuit 4 only needs to rectify high-frequency power, and may be a half-wave rectifier circuit, for example.
  • the direct current reactor 5 smoothes the direct current that the rectifier circuit 4 outputs to the inverter circuit 7.
  • the inverter circuit 7 is, for example, a single-phase full-bridge type PWM control inverter and includes four switching elements.
  • the inverter circuit 7 converts the DC power input from the rectifier circuit 4 into AC power and outputs it by switching the switching element according to the switching drive signal input from the control circuit 8.
  • the inverter circuit 7 only needs to convert DC power into AC power, and may be, for example, a half-bridge type or an inverter circuit having another configuration.
  • the switching drive signal corresponds to an example of “drive signal”.
  • the voltage superimposing circuit 6 is disposed between the rectifying circuit 4 and the inverter circuit 7, and when the polarity of the output current of the inverter circuit 7 is switched, a high voltage is applied between the output terminals a and b of the welding power source device A1. Superimpose.
  • the high voltage is for improving the re-ignitability at the time of polarity switching, and may be referred to as “re-ignition voltage” below.
  • the voltage superimposing circuit 6 includes a diode 61, a re-ignition capacitor 62, a charging circuit 63 and a discharging circuit 64.
  • the re-ignition capacitor 62 is a capacitor having a predetermined capacitance or more, and is charged with a high voltage (re-ignition voltage) to be superimposed on the output of the welding power source device A1.
  • the re-ignition capacitor 62 is connected in parallel to the rectifier circuit 4.
  • the re-ignition capacitor 62 is charged by the charging circuit 63 and discharged by the discharging circuit 64.
  • the charging circuit 63 is a circuit for charging the re-ignition capacitor 62 with a re-ignition voltage, and is connected to the re-ignition capacitor 62 in parallel.
  • FIG. 2A is a diagram illustrating an example of the charging circuit 63.
  • the charging circuit 63 includes an insulated forward converter.
  • the charging circuit 63 includes a drive circuit 63a for driving the isolated forward converter.
  • the drive circuit 63a outputs a pulse signal for driving the switching element 63b based on a charge circuit drive signal input from a charge control unit 86 described later.
  • the drive circuit 63a outputs a predetermined pulse signal to the switching element 63b while the charging circuit drive signal is on (for example, a high level signal).
  • the re-ignition capacitor 62 is charged.
  • the drive circuit 63a does not output a pulse signal while the charging circuit drive signal is off (for example, a low level signal). Therefore, charging of the re-ignition capacitor 62 is stopped. That is, the charging circuit 63 switches between a state where the re-ignition capacitor 62 is charged and a state where it is not charged based on the charging circuit drive signal.
  • the charge control unit 86 may directly input a pulse signal as a charge circuit drive signal to the switching element 63b. Further, the configuration of the charging circuit 63 is not limited.
  • the discharge circuit 64 discharges the re-ignition voltage charged in the re-ignition capacitor 62 and is connected to the re-ignition capacitor 62 in series.
  • FIG. 2B is a diagram illustrating an example of the discharge circuit 64.
  • the discharge circuit 64 includes a switching element 64a and a current limiting resistor 64b.
  • the switching element 64a is an IGBT (Insulated Gate Bipolar Transistor: an insulated gate bipolar transistor).
  • the switching element 64a may be a bipolar transistor, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or the like.
  • the switching element 64 a and the current limiting resistor 64 b are connected in series and are connected in series to the re-ignition capacitor 62.
  • the emitter terminal of the switching element 64a is connected to the positive terminal of the rectifier circuit 4, and the collector terminal of the switching element 64a is connected to one terminal of the current limiting resistor 64b.
  • the current limiting resistor 64b may be connected to the emitter terminal side of the switching element 64a.
  • a discharge circuit drive signal is input to the gate terminal of the switching element 64a from a discharge control unit 85 described later.
  • the switching element 64a is turned on while the discharge circuit drive signal is on (for example, a high level signal). As a result, the re-ignition voltage charged in the re-ignition capacitor 62 is discharged and is superimposed on the output voltage of the rectifier circuit 4 via the current limiting resistor 64b.
  • the switching element 64a is turned off while the discharge circuit drive signal is off (for example, a low level signal). Thereby, the discharge of the re-ignition voltage is stopped. That is, the discharge circuit 64 switches between a state where the re-ignition capacitor 62 is discharged and a state where it is not discharged based on the discharge circuit drive signal.
  • the configuration of the discharge circuit 64 is not limited.
  • the diode 61 is connected in parallel to the discharge circuit 64, the anode terminal is connected to the positive terminal of the input of the inverter circuit 7, and the cathode terminal is connected to the re-ignition capacitor 62.
  • the diode 61 causes the re-ignition capacitor 62 to absorb the transient voltage of the input voltage of the inverter circuit 7.
  • the current sensor 91 detects the output current of the welding power source device A1, and in this embodiment, is disposed on a connection line that connects one output terminal of the inverter circuit 7 and the output terminal a.
  • the current sensor 91 detects an instantaneous value of the output current and inputs it to the control circuit 8. In this embodiment, the case where the current flows from the inverter circuit 7 toward the output terminal a is positive, and the case where the current flows from the output terminal a toward the inverter circuit 7 is negative.
  • the voltage sensor 92 detects the voltage between the terminals of the re-ignition capacitor 62.
  • the voltage sensor 92 detects the voltage between the terminals and inputs it to the control circuit 8.
  • the control circuit 8 is a circuit for controlling the welding power source device A1, and is realized by, for example, a microcomputer.
  • the control circuit 8 receives the instantaneous value of the output current from the current sensor 91 and receives the voltage across the re-ignition capacitor 62 from the voltage sensor 92. Then, drive signals are output to the inverter circuit 7, the charging circuit 63, and the discharging circuit 64, respectively.
  • the control circuit 8 includes a current control unit 81, a current target setting unit 82, a polarity switching control unit 83, a waveform target setting unit 84, a discharge control unit 85, and a charge control unit 86.
  • the current control unit 81 controls the inverter circuit 2.
  • the current control unit 81 calculates an effective value from the instantaneous value of the output current input from the current sensor 91, and based on the effective value and the effective value target value input from the current target setting unit 82, the inverter circuit 2.
  • a drive signal for controlling the switching element is generated and output to the inverter circuit 2.
  • the polarity switching control unit 83 controls the inverter circuit 7.
  • the polarity switching control unit 83 performs switching for controlling the switching elements of the inverter circuit 7 based on the instantaneous value of the output current input from the current sensor 91 and the current waveform target value input from the waveform target setting unit 84.
  • a drive signal is generated and output to the inverter circuit 7.
  • the current waveform target value corresponds to an example of “control target”.
  • the discharge control unit 85 controls the discharge circuit 64.
  • the discharge control unit 85 generates a discharge circuit drive signal for controlling the discharge circuit 64 based on the instantaneous value of the output current input from the current sensor 91 and the switching drive signal input from the polarity switching control unit 83. Generated and output to the discharge circuit 64.
  • the output current (see FIG. 3B) of the welding power source A1 changes according to the switching drive signal (see FIG. 3A).
  • the output terminal a (workpiece W) is positive when the switch is on
  • the output terminal b (covered arc welding rod B) is negative
  • the output terminal a (workpiece) when off. W) is negative and output terminal b (covered arc welding rod B) is positive.
  • the output current of the welding power source device A1 decreased from when the switching drive signal was switched from on to off (time t1 in FIGS. 3A to 3E) and passed zero (time t2 in FIGS. 3A to 3E) and the polarity changed.
  • the minimum current value is reached (time t3 in FIGS. 3A to 3E).
  • the output current of the welding power source device A1 increases from when the switching drive signal is switched from OFF to ON (time t5 in FIGS. 3A to 3E), passes the zero (time t6 in FIGS. 3A to 3E), and has a polarity.
  • the maximum current value is reached (time t7 in FIGS. 3A to 3E).
  • the discharge controller 85 generates a discharge circuit drive signal so as to be turned on when the polarity of the output current of the welding power supply device A1 changes. Specifically, the discharge controller 85 switches on when the switching drive signal is switched (time t1, t5 in FIGS.
  • the discharge control unit 85 determines that the maximum current value is reached when the instantaneous current value is equal to or greater than the predetermined first threshold value. When the instantaneous current value is equal to or less than the predetermined second threshold, it is determined that the minimum current value has been reached.
  • the charging control unit 86 controls the charging circuit 63.
  • the charge control unit 86 controls the charging circuit 63 based on the instantaneous value of the output current input from the current sensor 91 and the voltage across the terminals of the re-ignition capacitor 62 input from the voltage sensor 92.
  • a circuit drive signal is generated and output to the charging circuit 63.
  • the voltage across the re-ignition capacitor 62 is output when the discharge circuit drive signal (see FIG. 3C) is turned on (time t1 in FIGS. 3A to 3E).
  • the polarity of the current changes (time t2 in FIGS. 3A to 3E)
  • it decreases due to the discharge of the re-ignition capacitor 62.
  • the re-ignition capacitor 62 is charged to a predetermined voltage, it is not necessary to perform further charging.
  • the charging control unit 86 generates a charging circuit drive signal so as to be turned on after the re-ignition capacitor 62 is discharged until the re-ignition capacitor 62 reaches a predetermined voltage. Specifically, the charge controller 86 switches the discharge circuit drive signal to OFF (time t3, t7 in FIGS. 3A to 3E), that is, the instantaneous value of the output current becomes the maximum current value or the minimum current value.
  • the charging circuit generates a pulse signal that is turned on when the voltage is turned on and turned off when the voltage between the terminals of the re-ignition capacitor 62 reaches a predetermined voltage (time t4, t8 in FIGS. 3A to 3E). It outputs as a drive signal (refer FIG. 3D).
  • the arc welding can be performed by causing the coated arc welding rod B to generate an arc between the tip and the workpiece W by the AC power output from the welding power source device A1.
  • the discharge control unit 85 of the welding power supply device A1 generates a discharge circuit drive signal that is turned on when the polarity of the output current of the welding power supply device A1 changes.
  • the discharge circuit 64 receives a discharge circuit drive signal input from the discharge control unit 85. Thereby, the discharge circuit 64 can superimpose the re-ignition voltage charged in the re-ignition capacitor 62 on the output voltage of the rectifier circuit 4 when the polarity of the output current of the welding power supply device A1 changes.
  • the DC reactor 5 can be reduced in size.
  • the transformer 3 is a high frequency transformer, it is smaller and lighter than a commercial frequency transformer. Accordingly, the welding power source device A1 can be reduced in size and weight as compared with the case of the coated arc welding system according to the comparative example.
  • the discharge circuit 64 controls the discharge based on the discharge circuit drive signal input from the discharge control unit 85.
  • the discharge circuit drive signal (see FIG. 3C) is turned on when the switching drive signal (see FIG. 3A) is switched, and is turned off when the output current (see FIG. 3B) reaches the maximum current value or the minimum current value. Switch to Therefore, when the polarity of the output current of the welding power source device A1 changes, the discharge circuit drive signal is always on, so the discharge circuit 64 can appropriately superimpose the re-ignition voltage.
  • the charging circuit 63 controls charging based on the charging circuit drive signal input from the charging control unit 86.
  • the charging circuit drive signal (see FIG. 3D) is turned on when the discharge circuit drive signal (see FIG. 3C) is turned off. Therefore, the charging circuit 63 can start charging immediately after discharging. Thereby, the charge time until the next discharge can be lengthened. Further, the charging circuit drive signal is switched off when the voltage between the terminals of the re-ignition capacitor 62 (see FIG. 3E) becomes a predetermined voltage. Thereby, the charging circuit 63 can suppress charging the re-ignition capacitor 62 more than necessary.
  • the charging control unit 86 generates the charging circuit drive signal based on the instantaneous value of the output current and the voltage between the terminals of the re-ignition capacitor 62 . Absent. As long as the re-ignition capacitor 62 can be charged with the re-ignition voltage by the next discharge timing, the timing of starting and ending charging is not limited. Further, the charging circuit 63 may be continuously charged. In this case, the charging control unit 86 is not necessary, and the drive circuit 63a may continue to output a pulse signal for driving the switching element 63b.
  • the discharge control unit 85 generates the discharge circuit drive signal based on the instantaneous value of the output current and the switching drive signal.
  • the present invention is not limited to this. Since it is sufficient that the re-ignition voltage can be superimposed when the polarity of the output current of the welding power source device A1 changes, the discharge circuit drive signal may be turned on before the polarity is changed and turned off after the polarity is changed. For example, the discharge circuit drive signal may be switched off when a predetermined time has elapsed since the instantaneous value of the output current becomes zero.
  • the discharge control unit 85 receives a current waveform target value from the waveform target setting unit 84 instead of the switching drive signal from the polarity switching control unit 83, and the current waveform target value is When switched, the discharge circuit drive signal may be switched on. In this case as well, the waveform of the discharge circuit drive signal is the same as when switching based on the switching drive signal.
  • the discharge circuit drive signal may be switched on.
  • the waveform of the discharge circuit drive signal is the same as when switching based on the switching drive signal.
  • a first threshold value smaller than the maximum current value and larger than zero and a second threshold value larger than the minimum current value and smaller than zero are set, and the discharge circuit drive signal is set so that the instantaneous value of the output current is the first threshold value and the second threshold value. It may be switched on when entering a range between and off when switching out of the range. Even in this case, the discharge circuit drive signal is turned on before the polarity is changed and turned off after the polarity is changed.
  • the waveform of the output current may be a sine wave.
  • the waveform target setting unit 84 outputs a sine wave signal as the current waveform target value, and the polarity switching control unit 83 outputs the instantaneous value of the output current input from the current sensor 91 and the current waveform target value input from the waveform target setting unit 84. If the switching drive signal is generated based on the above, the waveform of the output current can be a sine wave.
  • the discharge circuit drive signal may be generated based on the instantaneous value of the output current detected by the current sensor 91. For example, a first threshold value that is smaller than the maximum current value and larger than zero and a second threshold value that is larger than the minimum current value and smaller than zero are set, and the discharge circuit drive signal is set as the instantaneous value of the output current as the first threshold value and the second threshold value. It is possible to switch on when entering the range between and to switch off when outside the range. If the waveform of the output current is a sine wave, the generated arc becomes wider, so that the welding mark can be made wider. Moreover, the sound generated from welding power supply device A1 can be suppressed.
  • the present invention is not limited to this.
  • the output terminal a (workpiece W) is positive and the output terminal b (covered arc welding rod B) is negative, so that the output terminal a (workpiece W) is negative and the output terminal b ( It is known that arc breakage is likely to occur when the coated arc welding rod B) switches to the reverse polarity which is positive. Therefore, the re-ignition voltage may be superimposed only when switching from positive polarity to reverse polarity, and the re-ignition voltage may not be superimposed when switching from negative polarity to positive polarity.
  • a modification in this case will be described with reference to FIGS. 5A to 5E. In this modification, only the method of generating the discharge circuit drive signal by the discharge control unit 85 is changed.
  • FIGS. 5A to 5E are time charts showing waveforms of respective signals in the modified example.
  • FIG. 5A shows a switching drive signal generated by the polarity switching control unit 83, which is the same as that shown in FIG. 3A.
  • FIG. 5B shows the output current of the welding power source device A1, which is the same as that shown in FIG. 3B.
  • FIG. 5C shows a discharge circuit drive signal generated by the discharge control unit 85.
  • FIG. 5D shows a charging circuit drive signal generated by the charging control unit 86.
  • FIG. 5E shows the voltage between the terminals of the re-ignition capacitor 62.
  • the discharge control unit 85 generates a discharge circuit drive signal so that it is turned on when the polarity of the output current of the welding power source device A1 changes from positive polarity to reverse polarity. Specifically, the discharge control unit 85 is switched on when the switching drive signal (see FIG. 5A) is switched from on to off (time t1 in FIGS. 5A to 5E), and the output current of the welding power supply device A1 ( When the minimum current value is reached (see FIG. 5B) (time t3 in FIGS. 5A to 5E), a pulse signal that is turned off is generated and output as a discharge circuit drive signal (see FIG. 5C). When the switching drive signal is switched from OFF to ON (time t5 in FIGS. 5A to 5E), and when the output current of the welding power supply device A1 reaches the maximum current value (FIGS. 5A to 5E) At time t7), the discharge circuit drive signal is not switched.
  • the discharge circuit drive signal (see FIG. 5C) generated by the discharge controller 85 is different from the discharge drive signal shown in FIG. 3C
  • the voltage between the terminals of the capacitor 62 (see FIG. 5E) has a waveform different from that shown in FIGS. 3D and 3E.
  • the voltage superimposing circuit 6 may be arranged on the output side of the inverter circuit 7. This case will be described below as a second embodiment.
  • FIG. 6 is a diagram showing an overall configuration of a covered arc welding system according to the second embodiment.
  • the same or similar elements as those in the covered arc welding system (see FIG. 1) according to the first embodiment are denoted by the same reference numerals.
  • the control circuit 8 is illustrated in a simplified manner.
  • the welding power supply device A2 is different from the welding power supply device A1 according to the first embodiment in that the voltage superimposing circuit 6 is arranged on the output side of the inverter circuit 7.
  • the voltage superimposing circuit 6 is disposed on the output side of the inverter circuit 7 and superimposes a re-ignition voltage between the output terminals a and b so as to increase the potential of the output terminal b (covered arc welding rod B). It is configured.
  • the discharge circuit 64 is conductive when the switching drive signal (see FIG. 5A) switches from on to off (time t1 in FIGS. 5A to 5E), and the polarity of the output current (see FIG. 5B) changes.
  • time t2 in FIGS. 5A to 5E the re-ignition capacitor 62 is discharged, and the re-ignition voltage is superimposed between the output terminals a and b.
  • arc breakage is more likely to occur, and since re-ignition voltage can be superimposed when switching from positive polarity to reverse polarity, occurrence of arc breakage can be suppressed.
  • the welding power source device A2 can be reduced in size and weight.
  • arc break is relatively difficult to occur, and when the reverse polarity is switched to the positive polarity, the re-ignition voltage is not superimposed. Therefore, compared with the first embodiment, the current limiting resistance 64b Loss can be reduced. Further, since the time from discharge of the re-ignition voltage to the next discharge becomes longer, it is particularly effective when it takes time to charge the re-ignition voltage.
  • the covering arc welding system and the welding power supply apparatus for covering arc welding according to the present disclosure are not limited to the above-described embodiments.
  • the specific configuration of each part of the coated arc welding system and the welding power supply apparatus for the coated arc welding according to the present disclosure can be modified in various ways.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
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  • Arc Welding Control (AREA)
  • Generation Of Surge Voltage And Current (AREA)

Abstract

One aspect of the present invention provides a shielded metal arc welding system. The shielded metal arc welding system comprises a shielded metal arc welding rod and a welding power supply device that supplies power to the shielded metal arc welding rod. The welding power supply device comprises a rectifier circuit, a DC reactor, an inverter circuit, and a voltage superimposition circuit. The rectifier circuit rectifies AC power. The DC reactor smooths the output of the rectifier circuit. The inverter circuit converts DC power output by the DC reactor into AC power and outputs the result to the shielded metal arc welding rod. The voltage superimposition circuit superimposes a restriking voltage on the output to the shielded metal arc welding rod. The voltage superimposition circuit superimposes the restriking voltage when the polarity of current output from the inverter circuit switches.

Description

被覆アーク溶接システム、および、被覆アーク溶接用の溶接電源装置Clad arc welding system and welding power supply for clad arc welding
　本開示は、被覆アーク溶接システム、および、被覆アーク溶接用の溶接電源装置に関する。 The present disclosure relates to a coated arc welding system and a welding power supply device for coated arc welding.
　屋外での作業に適した溶接として、被覆アーク溶接が知られている。被覆アーク溶接では、被覆アーク溶接棒と被加工物との間にアークを発生させて、当該アークの熱によって溶接が行われる。被覆アーク溶接の場合、炭酸ガスアーク溶接などとは異なり、ガスを吹き付ける必要がない。したがって、簡易な装置で溶接作業を行うことができる。また、風によってガスが散らされる屋外でも、溶接作業を行うことができる。 被覆 Covered arc welding is known as welding suitable for outdoor work. In covered arc welding, an arc is generated between a covered arc welding rod and a workpiece, and welding is performed by the heat of the arc. In the case of covered arc welding, unlike carbon dioxide arc welding, there is no need to spray gas. Therefore, welding work can be performed with a simple device. Also, welding work can be performed outdoors where gas is scattered by the wind.
　図７は、比較例にかかる被覆アーク溶接システムの一例を示す図である（なお、図７に示すシステムは、公知になっているとは限らない）。図７に示す被覆アーク溶接システムは、被覆アーク溶接棒Ｂと、被覆アーク溶接棒Ｂを保持して溶接電流を通電するための溶接棒ホルダＣと、溶接棒ホルダＣを介して被覆アーク溶接棒Ｂに電力を供給する溶接電源装置Ａ１００とを備えている。溶接電源装置Ａ１００は、交流電力を変圧するトランス３００を備えており、商用電源Ｄからの交流電力をトランス３００の一次側に入力し、トランス３００の二次側から変圧後の交流電力を出力する。溶接電源装置Ａ１００の一方の出力端子ａは、ケーブルによって被加工物Ｗに接続されており、他方の出力端子ｂは、ケーブルによって溶接棒ホルダＣに接続されている。溶接電源装置Ａ１００は、被覆アーク溶接棒Ｂの先端と被加工物Ｗとの間にアークを発生させ、電力を供給する。 FIG. 7 is a diagram showing an example of a coated arc welding system according to a comparative example (note that the system shown in FIG. 7 is not necessarily publicly known). The coated arc welding system shown in FIG. 7 includes a coated arc welding rod B, a welding rod holder C for holding the coated arc welding rod B and energizing a welding current, and a coated arc welding rod via the welding rod holder C. And a welding power supply device A100 that supplies electric power to B. The welding power supply device A100 includes a transformer 300 that transforms AC power, inputs AC power from the commercial power source D to the primary side of the transformer 300, and outputs AC power after transformation from the secondary side of the transformer 300. . One output terminal a of the welding power source device A100 is connected to the workpiece W by a cable, and the other output terminal b is connected to the welding rod holder C by a cable. The welding power source device A100 generates an arc between the tip of the coated arc welding rod B and the workpiece W, and supplies electric power.
　図７に示す被覆アーク溶接システムにおいては、出力電流の極性が変わるときのアーク切れを防ぐために、トランス３００の二次側のリアクタンスを大きくする必要があった。したがって、トランス３００が大型化し、溶接電源装置Ａ１００を小型軽量化するための妨げになっていた。 In the coated arc welding system shown in FIG. 7, it is necessary to increase the reactance on the secondary side of the transformer 300 in order to prevent arc breakage when the polarity of the output current changes. Therefore, the transformer 300 is increased in size, which hinders the welding power supply device A100 from being reduced in size and weight.
　本開示は、上記した事情のもとで考え出されたものであって、より好適な被覆アーク溶接システムを提供することを目的の一つとする。たとえば、本開示は、出力電流の極性が変わるときのアーク切れを抑制し、かつ、溶接電源装置を小型軽量化できる被覆アーク溶接システムを提供することを目的の一つとしている。 This disclosure has been conceived under the circumstances described above, and an object thereof is to provide a more suitable coated arc welding system. For example, an object of the present disclosure is to provide a coated arc welding system that suppresses arc breakage when the polarity of the output current changes and that can reduce the size and weight of the welding power supply device.
　本開示の第１の側面によると、被覆アーク溶接システムが提供される。前記被覆アーク溶接システムは、被覆アーク溶接棒と、前記被覆アーク溶接棒に電力を供給する溶接電源装置と、を含む。前記溶接電源装置は、整流回路と、直流リアクトルと、インバータ回路と、電圧重畳回路と、を含む。前記整流回路は、交流電力を整流する。前記直流リアクトルは、前記整流回路の出力を平滑化する。前記インバータ回路は、前記直流リアクトルが出力する直流電力を交流電力に変換して、前記被覆アーク溶接棒に出力する。前記電圧重畳回路は、前記被覆アーク溶接棒への出力に再点弧電圧を重畳する。前記電圧重畳回路は、前記インバータ回路の出力電流の極性が切り替わるときに、前記再点弧電圧を重畳する。 According to a first aspect of the present disclosure, a coated arc welding system is provided. The said covering arc welding system contains a covering arc welding rod and the welding power supply device which supplies electric power to the said covering arc welding rod. The welding power supply device includes a rectifier circuit, a DC reactor, an inverter circuit, and a voltage superimposing circuit. The rectifier circuit rectifies AC power. The DC reactor smoothes the output of the rectifier circuit. The inverter circuit converts DC power output from the DC reactor into AC power and outputs the AC power to the coated arc welding rod. The voltage superimposing circuit superimposes a re-ignition voltage on the output to the coated arc welding rod. The voltage superimposing circuit superimposes the re-ignition voltage when the polarity of the output current of the inverter circuit is switched.
　本開示の第２の側面によると、被覆アーク溶接用の溶接電源装置が提供される。前記溶接電源装置は、整流回路と、直流リアクトルと、インバータ回路と、電圧重畳回路と、を含む。前記整流回路は、交流電力を整流する。直流リアクトルは、前記整流回路の出力を平滑化する。前記インバータ回路は、前記直流リアクトルが出力する直流電力を交流電力に変換して、被覆アーク溶接棒に出力する。前記電圧重畳回路は、前記被覆アーク溶接棒への出力に再点弧電圧を重畳する。前記電圧重畳回路は、前記インバータ回路の出力電流の極性が切り替わるときに、前記再点弧電圧を重畳する。 According to the second aspect of the present disclosure, a welding power supply device for covering arc welding is provided. The welding power supply device includes a rectifier circuit, a DC reactor, an inverter circuit, and a voltage superimposing circuit. The rectifier circuit rectifies AC power. The DC reactor smoothes the output of the rectifier circuit. The inverter circuit converts DC power output from the DC reactor into AC power and outputs the AC power to the coated arc welding rod. The voltage superimposing circuit superimposes a re-ignition voltage on the output to the coated arc welding rod. The voltage superimposing circuit superimposes the re-ignition voltage when the polarity of the output current of the inverter circuit is switched.
第１実施形態に係る被覆アーク溶接システムの全体構成を示す図である。It is a figure showing the whole covering arc welding system composition concerning a 1st embodiment. 第１実施形態に係る充電回路の一例を示す図である。It is a figure which shows an example of the charging circuit which concerns on 1st Embodiment. 第１実施形態に係る放電回路の一例を示す図である。It is a figure which shows an example of the discharge circuit which concerns on 1st Embodiment. 第１実施形態に係る溶接電源装置の各信号の波形を示すタイムチャートである。It is a time chart which shows the waveform of each signal of the welding power supply device concerning a 1st embodiment. 第１実施形態に係る制御回路の変形例の内部構成を示す機能ブロック図である。It is a functional block diagram which shows the internal structure of the modification of the control circuit which concerns on 1st Embodiment. 第１実施形態に係る放電制御部の変形例における、各信号の波形を示すタイムチャートである。It is a time chart which shows the waveform of each signal in the modification of the discharge control part which concerns on 1st Embodiment. 第２実施形態に係る被覆アーク溶接システムの全体構成を示す図である。It is a figure which shows the whole structure of the covering arc welding system which concerns on 2nd Embodiment. 比較例にかかる被覆アーク溶接システムの全体構成を示す図である。It is a figure which shows the whole structure of the covering arc welding system concerning a comparative example.
　以下、本開示の好ましい実施の形態を、添付図面を参照して具体的に説明する。 Hereinafter, preferred embodiments of the present disclosure will be specifically described with reference to the accompanying drawings.
　図１は、第１実施形態に係る被覆アーク溶接システムの全体構成を示す図である。図１に示すように、被覆アーク溶接システムは、溶接電源装置Ａ１、被覆アーク溶接棒Ｂおよび溶接棒ホルダＣを備えている。溶接棒ホルダＣは、作業者が把持して溶接を行うためのものであり、被覆アーク溶接棒Ｂを保持し、溶接電源装置Ａ１から入力される交流電流を被覆アーク溶接棒Ｂに通電する。溶接電源装置Ａ１は、商用電源Ｄから入力される交流電力を変換して、出力端子ａ，ｂから出力する。一方の出力端子ａは、ケーブルによって被加工物Ｗに接続されている。他方の出力端子ｂは、ケーブルによって溶接棒ホルダＣに接続されている。溶接電源装置Ａ１は、被覆アーク溶接棒Ｂの先端と被加工物Ｗとの間にアークを発生させて、電力を供給する。当該アークの熱によって、溶接が行われる。 FIG. 1 is a diagram showing an overall configuration of a coated arc welding system according to the first embodiment. As shown in FIG. 1, the coated arc welding system includes a welding power source device A <b> 1, a coated arc welding rod B, and a welding rod holder C. The welding rod holder C is for an operator to hold and weld, and holds the covered arc welding rod B, and supplies the alternating current input from the welding power source device A1 to the covered arc welding rod B. The welding power source device A1 converts AC power input from the commercial power source D and outputs it from the output terminals a and b. One output terminal a is connected to the workpiece W by a cable. The other output terminal b is connected to the welding rod holder C by a cable. The welding power supply device A1 generates an arc between the tip of the covered arc welding rod B and the workpiece W to supply electric power. Welding is performed by the heat of the arc.
　溶接電源装置Ａ１は、整流平滑回路１、インバータ回路２、トランス３、整流回路４、直流リアクトル５、電圧重畳回路６、インバータ回路７、制御回路８、電流センサ９１および電圧センサ９２を備えている。 The welding power supply device A1 includes a rectifying / smoothing circuit 1, an inverter circuit 2, a transformer 3, a rectifying circuit 4, a DC reactor 5, a voltage superimposing circuit 6, an inverter circuit 7, a control circuit 8, a current sensor 91, and a voltage sensor 92. .
　整流平滑回路１は、商用電源Ｄから入力される交流電力を直流電力に変換して出力する。整流平滑回路１は、交流電流を整流する整流回路と、平滑する平滑コンデンサとを備えている。 The rectifying / smoothing circuit 1 converts AC power input from the commercial power source D into DC power and outputs it. The rectifying / smoothing circuit 1 includes a rectifying circuit for rectifying an alternating current and a smoothing capacitor for smoothing.
　インバータ回路２は、例えば、単相フルブリッジ型のＰＷＭ制御インバータであり、４つのスイッチング素子を備えている。インバータ回路２は、制御回路８から入力される駆動信号によってスイッチング素子をスイッチングさせることで、整流平滑回路１から入力される直流電力を高周波電力に変換して出力する。なお、インバータ回路２は直流電力を交流電力に変換するものであればよく、例えばハーフブリッジ型であってもよいし、その他の構成のインバータ回路であってもよい。 The inverter circuit 2 is, for example, a single-phase full-bridge type PWM control inverter and includes four switching elements. The inverter circuit 2 converts the DC power input from the rectifying / smoothing circuit 1 into high-frequency power by switching the switching element according to the drive signal input from the control circuit 8, and outputs the high-frequency power. The inverter circuit 2 only needs to convert DC power into AC power, and may be, for example, a half-bridge type or an inverter circuit having another configuration.
　トランス３は、インバータ回路２が出力する高周波電圧を変圧して、整流回路４に出力する。トランス３は、高周波用のトランスなので、商用周波数用のトランスと比べて、小型で軽量である。 The transformer 3 transforms the high-frequency voltage output from the inverter circuit 2 and outputs it to the rectifier circuit 4. Since the transformer 3 is a high frequency transformer, it is smaller and lighter than a commercial frequency transformer.
　整流回路４は、例えば全波整流回路であり、トランス３より入力される高周波電力を整流して、インバータ回路７に出力する。なお、整流回路４は、高周波電力を整流するものであればよく、例えば半波整流回路であってもよい。直流リアクトル５は、整流回路４がインバータ回路７に出力する直流電流を平滑化する。 The rectifier circuit 4 is, for example, a full-wave rectifier circuit, and rectifies high-frequency power input from the transformer 3 and outputs the rectified circuit to the inverter circuit 7. The rectifier circuit 4 only needs to rectify high-frequency power, and may be a half-wave rectifier circuit, for example. The direct current reactor 5 smoothes the direct current that the rectifier circuit 4 outputs to the inverter circuit 7.
　インバータ回路７は、例えば、単相フルブリッジ型のＰＷＭ制御インバータであり、４つのスイッチング素子を備えている。インバータ回路７は、制御回路８から入力されるスイッチング駆動信号によってスイッチング素子をスイッチングさせることで、整流回路４から入力される直流電力を交流電力に変換して出力する。なお、インバータ回路７は直流電力を交流電力に変換するものであればよく、例えばハーフブリッジ型であってもよいし、その他の構成のインバータ回路であってもよい。スイッチング駆動信号が「駆動信号」の一例に相当する。 The inverter circuit 7 is, for example, a single-phase full-bridge type PWM control inverter and includes four switching elements. The inverter circuit 7 converts the DC power input from the rectifier circuit 4 into AC power and outputs it by switching the switching element according to the switching drive signal input from the control circuit 8. The inverter circuit 7 only needs to convert DC power into AC power, and may be, for example, a half-bridge type or an inverter circuit having another configuration. The switching drive signal corresponds to an example of “drive signal”.
　電圧重畳回路６は、整流回路４とインバータ回路７との間に配置されており、インバータ回路７の出力電流の極性が切り替わるときに、溶接電源装置Ａ１の出力端子ａ，ｂ間に高電圧を重畳する。当該高電圧は、極性切り替え時の再点弧性を向上させるためのものであり、以下では「再点弧電圧」と記載する場合がある。電圧重畳回路６は、ダイオード６１、再点弧コンデンサ６２、充電回路６３および放電回路６４を備えている。 The voltage superimposing circuit 6 is disposed between the rectifying circuit 4 and the inverter circuit 7, and when the polarity of the output current of the inverter circuit 7 is switched, a high voltage is applied between the output terminals a and b of the welding power source device A1. Superimpose. The high voltage is for improving the re-ignitability at the time of polarity switching, and may be referred to as “re-ignition voltage” below. The voltage superimposing circuit 6 includes a diode 61, a re-ignition capacitor 62, a charging circuit 63 and a discharging circuit 64.
　再点弧コンデンサ６２は、所定の静電容量以上のコンデンサであり、溶接電源装置Ａ１の出力に重畳するための高電圧（再点弧電圧）を充電される。再点弧コンデンサ６２は、整流回路４に対して並列に接続されている。再点弧コンデンサ６２は、充電回路６３によって充電され、放電回路６４によって放電される。 The re-ignition capacitor 62 is a capacitor having a predetermined capacitance or more, and is charged with a high voltage (re-ignition voltage) to be superimposed on the output of the welding power source device A1. The re-ignition capacitor 62 is connected in parallel to the rectifier circuit 4. The re-ignition capacitor 62 is charged by the charging circuit 63 and discharged by the discharging circuit 64.
　充電回路６３は、再点弧コンデンサ６２に再点弧電圧を充電するための回路であり、再点弧コンデンサ６２に並列に接続されている。図２Ａは、充電回路６３の一例を示す図である。図２Ａに示すように、本実施形態では、充電回路６３は、絶縁型フォワードコンバータを備えている。また、充電回路６３は、絶縁型フォワードコンバータを駆動するための駆動回路６３ａを備えている。駆動回路６３ａは、後述する充電制御部８６から入力される充電回路駆動信号に基づいて、スイッチング素子６３ｂを駆動させるためのパルス信号を出力する。駆動回路６３ａは、充電回路駆動信号がオン（例えばハイレベル信号）の間、所定のパルス信号をスイッチング素子６３ｂに出力する。これにより、再点弧コンデンサ６２が充電される。一方、駆動回路６３ａは、充電回路駆動信号がオフ（例えばローレベル信号）の間、パルス信号の出力を行わない。よって、再点弧コンデンサ６２の充電は停止される。すなわち、充電回路６３は、充電回路駆動信号に基づいて、再点弧コンデンサ６２を充電する状態と充電しない状態とで切り替える。なお、駆動回路６３ａを設けずに、充電制御部８６が充電回路駆動信号としてパルス信号をスイッチング素子６３ｂに直接入力するようにしてもよい。また、充電回路６３の構成は限定されない。 The charging circuit 63 is a circuit for charging the re-ignition capacitor 62 with a re-ignition voltage, and is connected to the re-ignition capacitor 62 in parallel. FIG. 2A is a diagram illustrating an example of the charging circuit 63. As shown in FIG. 2A, in the present embodiment, the charging circuit 63 includes an insulated forward converter. The charging circuit 63 includes a drive circuit 63a for driving the isolated forward converter. The drive circuit 63a outputs a pulse signal for driving the switching element 63b based on a charge circuit drive signal input from a charge control unit 86 described later. The drive circuit 63a outputs a predetermined pulse signal to the switching element 63b while the charging circuit drive signal is on (for example, a high level signal). As a result, the re-ignition capacitor 62 is charged. On the other hand, the drive circuit 63a does not output a pulse signal while the charging circuit drive signal is off (for example, a low level signal). Therefore, charging of the re-ignition capacitor 62 is stopped. That is, the charging circuit 63 switches between a state where the re-ignition capacitor 62 is charged and a state where it is not charged based on the charging circuit drive signal. Instead of providing the drive circuit 63a, the charge control unit 86 may directly input a pulse signal as a charge circuit drive signal to the switching element 63b. Further, the configuration of the charging circuit 63 is not limited.
　放電回路６４は、再点弧コンデンサ６２に充電された再点弧電圧を放電するものであり、再点弧コンデンサ６２に直列に接続されている。図２Ｂは、放電回路６４の一例を示す図である。放電回路６４は、スイッチング素子６４ａおよび限流抵抗６４ｂを備えている。本実施形態では、スイッチング素子６４ａは、ＩＧＢＴ（Ｉｎｓｕｌａｔｅｄ　Ｇａｔｅ　ＢｉｐｏｌａｒＴｒａｎｓｉｓｔｏｒ　：　絶縁ゲート・バイポーラトランジスタ）である。なお、スイッチング素子６４ａは、バイポーラトランジスタ、ＭＯＳＦＥＴ（Ｍｅｔａｌ　Ｏｘｉｄｅ　Ｓｅｍｉｃｏｎｄｕｃｔｏｒ　Ｆｉｅｌｄ　Ｅｆｆｅｃｔ　Ｔｒａｎｓｉｓｔｏｒ）などであってもよい。スイッチング素子６４ａと限流抵抗６４ｂとは直列接続されて、再点弧コンデンサ６２に直列接続されている。スイッチング素子６４ａのエミッタ端子は整流回路４の正極側の端子に接続され、スイッチング素子６４ａのコレクタ端子は限流抵抗６４ｂの一方の端子に接続されている。なお、限流抵抗６４ｂをスイッチング素子６４ａのエミッタ端子側に接続するようにしてもよい。また、スイッチング素子６４ａのゲート端子には、後述する放電制御部８５から、放電回路駆動信号が入力される。スイッチング素子６４ａは、放電回路駆動信号がオン（例えばハイレベル信号）の間オン状態になる。これにより、再点弧コンデンサ６２に充電された再点弧電圧は放電され、限流抵抗６４ｂを介して、整流回路４の出力電圧に重畳される。一方、スイッチング素子６４ａは、放電回路駆動信号がオフ（例えばローレベル信号）の間オフ状態になる。これにより、再点弧電圧の放電は停止される。すなわち、放電回路６４は、放電回路駆動信号に基づいて、再点弧コンデンサ６２を放電する状態と放電しない状態とで切り替える。なお、放電回路６４の構成は限定されない。 The discharge circuit 64 discharges the re-ignition voltage charged in the re-ignition capacitor 62 and is connected to the re-ignition capacitor 62 in series. FIG. 2B is a diagram illustrating an example of the discharge circuit 64. The discharge circuit 64 includes a switching element 64a and a current limiting resistor 64b. In the present embodiment, the switching element 64a is an IGBT (Insulated Gate Bipolar Transistor: an insulated gate bipolar transistor). The switching element 64a may be a bipolar transistor, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or the like. The switching element 64 a and the current limiting resistor 64 b are connected in series and are connected in series to the re-ignition capacitor 62. The emitter terminal of the switching element 64a is connected to the positive terminal of the rectifier circuit 4, and the collector terminal of the switching element 64a is connected to one terminal of the current limiting resistor 64b. The current limiting resistor 64b may be connected to the emitter terminal side of the switching element 64a. In addition, a discharge circuit drive signal is input to the gate terminal of the switching element 64a from a discharge control unit 85 described later. The switching element 64a is turned on while the discharge circuit drive signal is on (for example, a high level signal). As a result, the re-ignition voltage charged in the re-ignition capacitor 62 is discharged and is superimposed on the output voltage of the rectifier circuit 4 via the current limiting resistor 64b. On the other hand, the switching element 64a is turned off while the discharge circuit drive signal is off (for example, a low level signal). Thereby, the discharge of the re-ignition voltage is stopped. That is, the discharge circuit 64 switches between a state where the re-ignition capacitor 62 is discharged and a state where it is not discharged based on the discharge circuit drive signal. The configuration of the discharge circuit 64 is not limited.
　ダイオード６１は、放電回路６４に並列接続されており、アノード端子がインバータ回路７の入力の正極側の端子に接続され、カソード端子が再点弧コンデンサ６２に接続されている。ダイオード６１は、インバータ回路７の入力電圧の過渡電圧を、再点弧コンデンサ６２に吸収させる。 The diode 61 is connected in parallel to the discharge circuit 64, the anode terminal is connected to the positive terminal of the input of the inverter circuit 7, and the cathode terminal is connected to the re-ignition capacitor 62. The diode 61 causes the re-ignition capacitor 62 to absorb the transient voltage of the input voltage of the inverter circuit 7.
　電流センサ９１は、溶接電源装置Ａ１の出力電流を検出するものであり、本実施形態では、インバータ回路７の一方の出力端子と出力端子ａとを接続する接続線に配置されている。電流センサ９１は、出力電流の瞬時値を検出して制御回路８に入力する。本実施形態では、電流がインバータ回路７から出力端子ａに向かって流れる場合を正としており、電流が出力端子ａからインバータ回路７に向かって流れる場合を負としている。 The current sensor 91 detects the output current of the welding power source device A1, and in this embodiment, is disposed on a connection line that connects one output terminal of the inverter circuit 7 and the output terminal a. The current sensor 91 detects an instantaneous value of the output current and inputs it to the control circuit 8. In this embodiment, the case where the current flows from the inverter circuit 7 toward the output terminal a is positive, and the case where the current flows from the output terminal a toward the inverter circuit 7 is negative.
　電圧センサ９２は、再点弧コンデンサ６２の端子間電圧を検出するものである。電圧センサ９２は、端子間電圧を検出して制御回路８に入力する。 The voltage sensor 92 detects the voltage between the terminals of the re-ignition capacitor 62. The voltage sensor 92 detects the voltage between the terminals and inputs it to the control circuit 8.
　制御回路８は、溶接電源装置Ａ１を制御するための回路であり、例えばマイクロコンピュータなどによって実現されている。制御回路８は、電流センサ９１から出力電流の瞬時値を入力され、電圧センサ９２から再点弧コンデンサ６２の端子間電圧を入力される。そして、インバータ回路７、充電回路６３および放電回路６４に、それぞれ駆動信号を出力する。制御回路８は、電流制御部８１、電流目標設定部８２、極性切替制御部８３、波形目標設定部８４、放電制御部８５および充電制御部８６を備えている。 The control circuit 8 is a circuit for controlling the welding power source device A1, and is realized by, for example, a microcomputer. The control circuit 8 receives the instantaneous value of the output current from the current sensor 91 and receives the voltage across the re-ignition capacitor 62 from the voltage sensor 92. Then, drive signals are output to the inverter circuit 7, the charging circuit 63, and the discharging circuit 64, respectively. The control circuit 8 includes a current control unit 81, a current target setting unit 82, a polarity switching control unit 83, a waveform target setting unit 84, a discharge control unit 85, and a charge control unit 86.
　電流制御部８１は、インバータ回路２を制御する。電流制御部８１は、電流センサ９１から入力される出力電流の瞬時値から実効値を算出し、当該実効値と電流目標設定部８２から入力される実効値目標値とに基づいて、インバータ回路２のスイッチング素子を制御するための駆動信号を生成して、インバータ回路２に出力する。 The current control unit 81 controls the inverter circuit 2. The current control unit 81 calculates an effective value from the instantaneous value of the output current input from the current sensor 91, and based on the effective value and the effective value target value input from the current target setting unit 82, the inverter circuit 2. A drive signal for controlling the switching element is generated and output to the inverter circuit 2.
　極性切替制御部８３は、インバータ回路７を制御する。極性切替制御部８３は、電流センサ９１から入力される出力電流の瞬時値と波形目標設定部８４から入力される電流波形目標値とに基づいて、インバータ回路７のスイッチング素子を制御するためのスイッチング駆動信号を生成して、インバータ回路７に出力する。電流波形目標値が「制御目標」の一例に相当する。 The polarity switching control unit 83 controls the inverter circuit 7. The polarity switching control unit 83 performs switching for controlling the switching elements of the inverter circuit 7 based on the instantaneous value of the output current input from the current sensor 91 and the current waveform target value input from the waveform target setting unit 84. A drive signal is generated and output to the inverter circuit 7. The current waveform target value corresponds to an example of “control target”.
　放電制御部８５は、放電回路６４を制御する。放電制御部８５は、電流センサ９１から入力される出力電流の瞬時値と、極性切替制御部８３から入力されるスイッチング駆動信号とに基づいて、放電回路６４を制御するための放電回路駆動信号を生成して、放電回路６４に出力する。 The discharge control unit 85 controls the discharge circuit 64. The discharge control unit 85 generates a discharge circuit drive signal for controlling the discharge circuit 64 based on the instantaneous value of the output current input from the current sensor 91 and the switching drive signal input from the polarity switching control unit 83. Generated and output to the discharge circuit 64.
　図３Ａ－Ｂに示すように、溶接電源装置Ａ１の出力電流（図３Ｂ参照）は、スイッチング駆動信号（図３Ａ参照）に応じて変化する。図３Ａに示すスイッチング駆動信号は、オンのときに出力端子ａ（被加工物Ｗ）を正、出力端子ｂ（被覆アーク溶接棒Ｂ）を負とし、オフのときに出力端子ａ（被加工物Ｗ）を負、出力端子ｂ（被覆アーク溶接棒Ｂ）を正とする。溶接電源装置Ａ１の出力電流は、スイッチング駆動信号がオンからオフに切り替わった時（図３Ａ－Ｅにおける時刻ｔ１）から減少し、ゼロを過ぎて（図３Ａ－Ｅにおける時刻ｔ２）極性が変わった後に最小電流値になる（図３Ａ－Ｅにおける時刻ｔ３）。また、溶接電源装置Ａ１の出力電流は、スイッチング駆動信号がオフからオンに切り替わった時（図３Ａ－Ｅにおける時刻ｔ５）から増加し、ゼロを過ぎて（図３Ａ－Ｅにおける時刻ｔ６）極性が変わった後に最大電流値になる（図３Ａ－Ｅにおける時刻ｔ７）。放電制御部８５は、溶接電源装置Ａ１の出力電流の極性が変わるときにオンとなるように、放電回路駆動信号を生成する。具体的には、放電制御部８５は、スイッチング駆動信号が切り換わった時（図３Ａ－Ｅにおける時刻ｔ１、ｔ５）にオンに切り替わり、出力電流の瞬時値が最大電流値または最小電流値になったとき（図３Ａ－Ｅにおける時刻ｔ３、ｔ７）にオフに切り替わるパルス信号を生成し、放電回路駆動信号として出力する（図３Ｃ参照）。実際には、電流センサ９１から入力される電流瞬時値は微小変動するので、放電制御部８５は、電流瞬時値が所定の第１閾値以上になった場合に最大電流値になったと判断し、電流瞬時値が所定の第２閾値以下になった場合に最小電流値になったと判断する。 As shown in FIGS. 3A and 3B, the output current (see FIG. 3B) of the welding power source A1 changes according to the switching drive signal (see FIG. 3A). 3A, the output terminal a (workpiece W) is positive when the switch is on, the output terminal b (covered arc welding rod B) is negative, and the output terminal a (workpiece) when off. W) is negative and output terminal b (covered arc welding rod B) is positive. The output current of the welding power source device A1 decreased from when the switching drive signal was switched from on to off (time t1 in FIGS. 3A to 3E) and passed zero (time t2 in FIGS. 3A to 3E) and the polarity changed. Later, the minimum current value is reached (time t3 in FIGS. 3A to 3E). In addition, the output current of the welding power source device A1 increases from when the switching drive signal is switched from OFF to ON (time t5 in FIGS. 3A to 3E), passes the zero (time t6 in FIGS. 3A to 3E), and has a polarity. After the change, the maximum current value is reached (time t7 in FIGS. 3A to 3E). The discharge controller 85 generates a discharge circuit drive signal so as to be turned on when the polarity of the output current of the welding power supply device A1 changes. Specifically, the discharge controller 85 switches on when the switching drive signal is switched (time t1, t5 in FIGS. 3A to 3E), and the instantaneous value of the output current becomes the maximum current value or the minimum current value. When this occurs (at times t3 and t7 in FIGS. 3A to 3E), a pulse signal that switches off is generated and output as a discharge circuit drive signal (see FIG. 3C). Actually, since the instantaneous current value input from the current sensor 91 slightly fluctuates, the discharge control unit 85 determines that the maximum current value is reached when the instantaneous current value is equal to or greater than the predetermined first threshold value. When the instantaneous current value is equal to or less than the predetermined second threshold, it is determined that the minimum current value has been reached.
　充電制御部８６は、充電回路６３を制御する。充電制御部８６は、電流センサ９１から入力される出力電流の瞬時値と、電圧センサ９２から入力される再点弧コンデンサ６２の端子間電圧とに基づいて、充電回路６３を制御するための充電回路駆動信号を生成して、充電回路６３に出力する。 The charging control unit 86 controls the charging circuit 63. The charge control unit 86 controls the charging circuit 63 based on the instantaneous value of the output current input from the current sensor 91 and the voltage across the terminals of the re-ignition capacitor 62 input from the voltage sensor 92. A circuit drive signal is generated and output to the charging circuit 63.
　図３Ｃ、３Ｅに示すように、再点弧コンデンサ６２の端子間電圧（図３Ｅ参照）は、放電回路駆動信号（図３Ｃ参照）がオンになって（図３Ａ－Ｅにおける時刻ｔ１）、出力電流（図３Ｂ参照）の極性が変わったとき（図３Ａ－Ｅにおける時刻ｔ２）に、再点弧コンデンサ６２の放電により低下する。次の放電のタイミング（図３Ａ－Ｅにおける時刻ｔ６）までに、再点弧コンデンサ６２に再点弧電圧を充電する必要がある。また、再点弧コンデンサ６２が所定の電圧まで充電された場合は、それ以上の充電を行う必要がない。充電制御部８６は、再点弧コンデンサ６２の放電後から、再点弧コンデンサ６２が所定の電圧になるまでオンとなるように、充電回路駆動信号を生成する。具体的には、充電制御部８６は、放電回路駆動信号がオフに切り換わったとき（図３Ａ－Ｅにおける時刻ｔ３、ｔ７）、すなわち、出力電流の瞬時値が最大電流値または最小電流値になったときにオンに切り換わり、再点弧コンデンサ６２の端子間電圧が所定の電圧になったとき（図３Ａ－Ｅにおける時刻ｔ４、ｔ８）にオフに切り換わるパルス信号を生成し、充電回路駆動信号として出力する（図３Ｄ参照）。 As shown in FIGS. 3C and 3E, the voltage across the re-ignition capacitor 62 (see FIG. 3E) is output when the discharge circuit drive signal (see FIG. 3C) is turned on (time t1 in FIGS. 3A to 3E). When the polarity of the current (see FIG. 3B) changes (time t2 in FIGS. 3A to 3E), it decreases due to the discharge of the re-ignition capacitor 62. It is necessary to charge the re-ignition capacitor 62 with the re-ignition voltage by the next discharge timing (time t6 in FIGS. 3A to 3E). Further, when the re-ignition capacitor 62 is charged to a predetermined voltage, it is not necessary to perform further charging. The charging control unit 86 generates a charging circuit drive signal so as to be turned on after the re-ignition capacitor 62 is discharged until the re-ignition capacitor 62 reaches a predetermined voltage. Specifically, the charge controller 86 switches the discharge circuit drive signal to OFF (time t3, t7 in FIGS. 3A to 3E), that is, the instantaneous value of the output current becomes the maximum current value or the minimum current value. The charging circuit generates a pulse signal that is turned on when the voltage is turned on and turned off when the voltage between the terminals of the re-ignition capacitor 62 reaches a predetermined voltage (time t4, t8 in FIGS. 3A to 3E). It outputs as a drive signal (refer FIG. 3D).
　本実施形態によると、溶接電源装置Ａ１が出力する交流電力によって、被覆アーク溶接棒Ｂが、その先端と被加工物Ｗとの間にアークを発生させて、アーク溶接を行うことができる。溶接電源装置Ａ１の放電制御部８５は、溶接電源装置Ａ１の出力電流の極性が変わるときにオンとなるような放電回路駆動信号を生成する。放電回路６４は、放電制御部８５より入力される放電回路駆動信号を入力される。これにより、放電回路６４は、溶接電源装置Ａ１の出力電流の極性が変わるときに、再点弧コンデンサ６２に充電された再点弧電圧を整流回路４の出力電圧に重畳することができる。したがって、溶接電源装置Ａ１の出力電流の極性が変わるときのアーク切れを抑制することができる。また、再点弧電圧の重畳によりアーク切れを抑制するので、アーク切れを抑制するためにリアクタンスを大きくする必要がない。したがって、直流リアクトル５を小型化することができる。また、トランス３は、高周波用のトランスなので、商用周波数用のトランスと比べて、小型で軽量である。これらにより、比較例にかかる被覆アーク溶接システムの場合と比べて、溶接電源装置Ａ１を小型軽量化することができる。 According to the present embodiment, the arc welding can be performed by causing the coated arc welding rod B to generate an arc between the tip and the workpiece W by the AC power output from the welding power source device A1. The discharge control unit 85 of the welding power supply device A1 generates a discharge circuit drive signal that is turned on when the polarity of the output current of the welding power supply device A1 changes. The discharge circuit 64 receives a discharge circuit drive signal input from the discharge control unit 85. Thereby, the discharge circuit 64 can superimpose the re-ignition voltage charged in the re-ignition capacitor 62 on the output voltage of the rectifier circuit 4 when the polarity of the output current of the welding power supply device A1 changes. Therefore, arc interruption when the polarity of the output current of the welding power source device A1 changes can be suppressed. In addition, since the arc break is suppressed by superimposing the re-ignition voltage, it is not necessary to increase the reactance in order to suppress the arc break. Therefore, the DC reactor 5 can be reduced in size. Further, since the transformer 3 is a high frequency transformer, it is smaller and lighter than a commercial frequency transformer. Accordingly, the welding power source device A1 can be reduced in size and weight as compared with the case of the coated arc welding system according to the comparative example.
　本実施形態によると、放電回路６４は、放電制御部８５より入力される放電回路駆動信号に基づいて、放電を制御する。放電回路駆動信号（図３Ｃ参照）は、スイッチング駆動信号（図３Ａ参照）が切り換わったときにオンに切り替わり、出力電流（図３Ｂ参照）が最大電流値または最小電流値になったときにオフに切り替わる。したがって、溶接電源装置Ａ１の出力電流の極性が変わるときには、放電回路駆動信号は必ずオンとなっているので、放電回路６４は再点弧電圧を適切に重畳することができる。 According to this embodiment, the discharge circuit 64 controls the discharge based on the discharge circuit drive signal input from the discharge control unit 85. The discharge circuit drive signal (see FIG. 3C) is turned on when the switching drive signal (see FIG. 3A) is switched, and is turned off when the output current (see FIG. 3B) reaches the maximum current value or the minimum current value. Switch to Therefore, when the polarity of the output current of the welding power source device A1 changes, the discharge circuit drive signal is always on, so the discharge circuit 64 can appropriately superimpose the re-ignition voltage.
　本実施形態によると、充電回路６３は、充電制御部８６より入力される充電回路駆動信号に基づいて、充電を制御する。充電回路駆動信号（図３Ｄ参照）は、放電回路駆動信号（図３Ｃ参照）がオフに切り換わったときにオンに切り換わる。したがって、充電回路６３は、放電後すぐに充電を開始することができる。これにより、次の放電までの充電時間を長くすることができる。また、充電回路駆動信号は、再点弧コンデンサ６２の端子間電圧（図３Ｅ参照）が所定の電圧になったときにオフに切り換わる。これにより、充電回路６３は、再点弧コンデンサ６２を必要以上に充電することを抑制することができる。 According to the present embodiment, the charging circuit 63 controls charging based on the charging circuit drive signal input from the charging control unit 86. The charging circuit drive signal (see FIG. 3D) is turned on when the discharge circuit drive signal (see FIG. 3C) is turned off. Therefore, the charging circuit 63 can start charging immediately after discharging. Thereby, the charge time until the next discharge can be lengthened. Further, the charging circuit drive signal is switched off when the voltage between the terminals of the re-ignition capacitor 62 (see FIG. 3E) becomes a predetermined voltage. Thereby, the charging circuit 63 can suppress charging the re-ignition capacitor 62 more than necessary.
　なお、本実施形態においては、充電制御部８６が、出力電流の瞬時値と再点弧コンデンサ６２の端子間電圧とに基づいて充電回路駆動信号を生成する場合について説明したが、これに限られない。次の放電のタイミングまでに再点弧コンデンサ６２に再点弧電圧を充電することができれば、充電の開始および終了のタイミングは限定されない。また、充電回路６３が常に充電し続けるようにしてもよい。この場合は、充電制御部８６は不要であり、駆動回路６３ａがスイッチング素子６３ｂを駆動させるためのパルス信号を出力し続けるようにすればよい。 In the present embodiment, the case where the charging control unit 86 generates the charging circuit drive signal based on the instantaneous value of the output current and the voltage between the terminals of the re-ignition capacitor 62 has been described. Absent. As long as the re-ignition capacitor 62 can be charged with the re-ignition voltage by the next discharge timing, the timing of starting and ending charging is not limited. Further, the charging circuit 63 may be continuously charged. In this case, the charging control unit 86 is not necessary, and the drive circuit 63a may continue to output a pulse signal for driving the switching element 63b.
　また、本実施形態においては、放電制御部８５が、出力電流の瞬時値とスイッチング駆動信号とに基づいて放電回路駆動信号を生成する場合について説明したが、これに限られない。溶接電源装置Ａ１の出力電流の極性が変わるときに再点弧電圧を重畳できればよいので、放電回路駆動信号は、極性が変わる前にオンになり、極性が変わった後にオフになればよい。例えば、出力電流の瞬時値がゼロになって所定時間が経過したときに、放電回路駆動信号をオフに切り換えるようにしてもよい。 In the present embodiment, the case where the discharge control unit 85 generates the discharge circuit drive signal based on the instantaneous value of the output current and the switching drive signal has been described. However, the present invention is not limited to this. Since it is sufficient that the re-ignition voltage can be superimposed when the polarity of the output current of the welding power source device A1 changes, the discharge circuit drive signal may be turned on before the polarity is changed and turned off after the polarity is changed. For example, the discharge circuit drive signal may be switched off when a predetermined time has elapsed since the instantaneous value of the output current becomes zero.
　また、図４Ａに示すように、放電制御部８５が、極性切替制御部８３からスイッチング駆動信号を入力される代わりに、波形目標設定部８４から電流波形目標値を入力され、電流波形目標値が切り換わったときに、放電回路駆動信号をオンに切り換えるようにしてもよい。この場合も、放電回路駆動信号の波形は、スイッチング駆動信号に基づいて切り替える場合と同様となる。 As shown in FIG. 4A, the discharge control unit 85 receives a current waveform target value from the waveform target setting unit 84 instead of the switching drive signal from the polarity switching control unit 83, and the current waveform target value is When switched, the discharge circuit drive signal may be switched on. In this case as well, the waveform of the discharge circuit drive signal is the same as when switching based on the switching drive signal.
　さらに、図４Ｂに示すように、放電制御部８５が、電流センサ９１から出力電流の瞬時値だけを入力され、出力電流の瞬時値が最大電流値から低下したとき、または、最小電流値から上昇したときに、放電回路駆動信号をオンに切り換えるようにしてもよい。この場合も、放電回路駆動信号の波形は、スイッチング駆動信号に基づいて切り替える場合と同様となる。また、最大電流値より小さくゼロより大きい第１閾値と、最小電流値より大きくゼロより小さい第２閾値とを設定し、放電回路駆動信号を、出力電流の瞬時値が第１閾値と第２閾値との間の範囲に入ったときにオンに切り替え、当該範囲から外れたときにオフに切り替えるようにしてもよい。この場合でも、放電回路駆動信号は、極性が変わる前にオンになり、極性が変わった後にオフになる。 Further, as shown in FIG. 4B, when the discharge controller 85 receives only the instantaneous value of the output current from the current sensor 91 and the instantaneous value of the output current decreases from the maximum current value, or increases from the minimum current value. In this case, the discharge circuit drive signal may be switched on. In this case as well, the waveform of the discharge circuit drive signal is the same as when switching based on the switching drive signal. Further, a first threshold value smaller than the maximum current value and larger than zero and a second threshold value larger than the minimum current value and smaller than zero are set, and the discharge circuit drive signal is set so that the instantaneous value of the output current is the first threshold value and the second threshold value. It may be switched on when entering a range between and off when switching out of the range. Even in this case, the discharge circuit drive signal is turned on before the polarity is changed and turned off after the polarity is changed.
　また、本実施形態においては、出力電流の波形が略矩形波である場合（図３Ｂ参照）について説明したが、これに限られない。出力電流の波形が正弦波であってもよい。波形目標設定部８４が電流波形目標値として正弦波信号を出力し、極性切替制御部８３が電流センサ９１から入力される出力電流の瞬時値と波形目標設定部８４から入力される電流波形目標値とに基づいてスイッチング駆動信号を生成するようにすれば、出力電流の波形を正弦波とすることができる。出力電流の波形が正弦波の場合、電流センサ９１が検出する出力電流の瞬時値に基づいて、放電回路駆動信号を生成すればよい。例えば、最大電流値より小さくゼロより大きい第１閾値と、最小電流値より大きくゼロより小さい第２閾値とを設定し、放電回路駆動信号を、出力電流の瞬時値が第１閾値と第２閾値との間の範囲に入ったときにオンに切り替え、当該範囲から外れたときにオフに切り替えるようにすればよい。出力電流の波形を正弦波とすると、発生するアークが幅広になるので、溶接痕を幅広のものとすることができる。また、溶接電源装置Ａ１からの発生音を抑制することができる。 In the present embodiment, the case where the waveform of the output current is a substantially rectangular wave (see FIG. 3B) has been described, but the present invention is not limited to this. The waveform of the output current may be a sine wave. The waveform target setting unit 84 outputs a sine wave signal as the current waveform target value, and the polarity switching control unit 83 outputs the instantaneous value of the output current input from the current sensor 91 and the current waveform target value input from the waveform target setting unit 84. If the switching drive signal is generated based on the above, the waveform of the output current can be a sine wave. When the waveform of the output current is a sine wave, the discharge circuit drive signal may be generated based on the instantaneous value of the output current detected by the current sensor 91. For example, a first threshold value that is smaller than the maximum current value and larger than zero and a second threshold value that is larger than the minimum current value and smaller than zero are set, and the discharge circuit drive signal is set as the instantaneous value of the output current as the first threshold value and the second threshold value. It is possible to switch on when entering the range between and to switch off when outside the range. If the waveform of the output current is a sine wave, the generated arc becomes wider, so that the welding mark can be made wider. Moreover, the sound generated from welding power supply device A1 can be suppressed.
　本実施形態においては、溶接電源装置Ａ１の出力電流の極性が変わるときに再点弧電圧を重畳する場合について説明したが、これに限られない。一般的に、出力端子ａ（被加工物Ｗ）が正で出力端子ｂ（被覆アーク溶接棒Ｂ）が負である正極性から、出力端子ａ（被加工物Ｗ）が負で出力端子ｂ（被覆アーク溶接棒Ｂ）が正である逆極性に切り換わるときに、アーク切れが発生しやすいことが知られている。したがって、正極性から逆極性に切り換わるときにのみ再点弧電圧を重畳させ、負極性から正極性に切り換わるときには再点弧電圧を重畳させないようにしてもよい。この場合の変形例について、図５Ａ－Ｅを参照して説明する。なお、当該変形例においては、放電制御部８５による放電回路駆動信号の生成方法が変わるだけである。 In the present embodiment, the case where the re-ignition voltage is superimposed when the polarity of the output current of the welding power source device A1 changes has been described, but the present invention is not limited to this. Generally, the output terminal a (workpiece W) is positive and the output terminal b (covered arc welding rod B) is negative, so that the output terminal a (workpiece W) is negative and the output terminal b ( It is known that arc breakage is likely to occur when the coated arc welding rod B) switches to the reverse polarity which is positive. Therefore, the re-ignition voltage may be superimposed only when switching from positive polarity to reverse polarity, and the re-ignition voltage may not be superimposed when switching from negative polarity to positive polarity. A modification in this case will be described with reference to FIGS. 5A to 5E. In this modification, only the method of generating the discharge circuit drive signal by the discharge control unit 85 is changed.
　図５Ａ－Ｅは、変形例における、各信号の波形を示すタイムチャートである。図５Ａは、極性切替制御部８３が生成するスイッチング駆動信号を示しており、図３Ａに示すものと同じである。図５Ｂは、溶接電源装置Ａ１の出力電流を示しており、図３Ｂに示すものと同じである。図５Ｃは、放電制御部８５が生成する放電回路駆動信号を示している。図５Ｄは、充電制御部８６が生成する充電回路駆動信号を示している。図５Ｅは、再点弧コンデンサ６２の端子間電圧を示している。 FIGS. 5A to 5E are time charts showing waveforms of respective signals in the modified example. FIG. 5A shows a switching drive signal generated by the polarity switching control unit 83, which is the same as that shown in FIG. 3A. FIG. 5B shows the output current of the welding power source device A1, which is the same as that shown in FIG. 3B. FIG. 5C shows a discharge circuit drive signal generated by the discharge control unit 85. FIG. 5D shows a charging circuit drive signal generated by the charging control unit 86. FIG. 5E shows the voltage between the terminals of the re-ignition capacitor 62.
　放電制御部８５は、溶接電源装置Ａ１の出力電流の極性が、正極性から逆極性に変わるときにオンとなるように、放電回路駆動信号を生成する。具体的には、放電制御部８５は、スイッチング駆動信号（図５Ａ参照）がオンからオフに切り換わったとき（図５Ａ－Ｅにおける時刻ｔ１）にオンに切り替わり、溶接電源装置Ａ１の出力電流（図５Ｂ参照）が最小電流値になったとき（図５Ａ－Ｅにおける時刻ｔ３）にオフに切り替わるパルス信号を生成し、放電回路駆動信号として出力する（図５Ｃ参照）。放電制御部８５は、スイッチング駆動信号がオフからオンに切り換わったとき（図５Ａ－Ｅにおける時刻ｔ５）、および、溶接電源装置Ａ１の出力電流が最大電流値になったとき（図５Ａ－Ｅにおける時刻ｔ７）には、放電回路駆動信号の切り替えを行わない。 The discharge control unit 85 generates a discharge circuit drive signal so that it is turned on when the polarity of the output current of the welding power source device A1 changes from positive polarity to reverse polarity. Specifically, the discharge control unit 85 is switched on when the switching drive signal (see FIG. 5A) is switched from on to off (time t1 in FIGS. 5A to 5E), and the output current of the welding power supply device A1 ( When the minimum current value is reached (see FIG. 5B) (time t3 in FIGS. 5A to 5E), a pulse signal that is turned off is generated and output as a discharge circuit drive signal (see FIG. 5C). When the switching drive signal is switched from OFF to ON (time t5 in FIGS. 5A to 5E), and when the output current of the welding power supply device A1 reaches the maximum current value (FIGS. 5A to 5E) At time t7), the discharge circuit drive signal is not switched.
　放電制御部８５が生成する放電回路駆動信号（図５Ｃ参照）が図３Ｃに示す放電駆動信号と異なるので、充電制御部８６が生成する充電回路駆動信号（図５Ｄ参照）、および、再点弧コンデンサ６２の端子間電圧（図５Ｅ参照）は、それぞれ、図３Ｄおよび図３Ｅに示すものと異なる波形になっている。 Since the discharge circuit drive signal (see FIG. 5C) generated by the discharge controller 85 is different from the discharge drive signal shown in FIG. 3C, the charge circuit drive signal (see FIG. 5D) generated by the charge controller 86 and re-ignition The voltage between the terminals of the capacitor 62 (see FIG. 5E) has a waveform different from that shown in FIGS. 3D and 3E.
　当該変形例においては、よりアーク切れが発生しやすい、正極性から逆極性に切り換わるときに再点弧電圧を重畳するので、アーク切れの発生を抑制することができる。また、比較的にアーク切れが発生しにくい、逆極性から正極性に切り換わるときには再点弧電圧を重畳させないので、逆極性から正極性に切り換わるときにも再点弧電圧を重畳する場合と比べて、限流抵抗６４ｂでの損失を低減することができる。また、再点弧電圧を放電してから次に放電するまでの時間が長くなるので、再点弧電圧を充電するために時間がかかる場合に、特に有効である。 In this modification, arc breakage is more likely to occur, and since re-ignition voltage is superimposed when switching from positive polarity to reverse polarity, occurrence of arc breakage can be suppressed. In addition, it is relatively difficult for arc breaks to occur, and re-ignition voltage is not superimposed when switching from reverse polarity to positive polarity. Therefore, re-ignition voltage is also superimposed when switching from reverse polarity to positive polarity. In comparison, the loss at the current limiting resistor 64b can be reduced. Further, since the time from discharge of the re-ignition voltage to the next discharge becomes longer, it is particularly effective when it takes time to charge the re-ignition voltage.
　上記変形例のように正極性から逆極性に切り換わるときにのみ再点弧電圧を重畳する場合は、電圧重畳回路６をインバータ回路７の出力側に配置するようにしてもよい。この場合を、第２実施形態として、以下に説明する。 When the re-ignition voltage is superimposed only when switching from positive polarity to reverse polarity as in the above modification, the voltage superimposing circuit 6 may be arranged on the output side of the inverter circuit 7. This case will be described below as a second embodiment.
　図６は、第２実施形態に係る被覆アーク溶接システムの全体構成を示す図である。図６において、第１実施形態に係る被覆アーク溶接システム（図１参照）と同一または類似の要素には、同一の符号を付している。なお、図６においては、制御回路８を簡略化して記載している。図６に示すように、溶接電源装置Ａ２は、電圧重畳回路６をインバータ回路７の出力側に配置している点で、第１実施形態に係る溶接電源装置Ａ１と異なる。 FIG. 6 is a diagram showing an overall configuration of a covered arc welding system according to the second embodiment. In FIG. 6, the same or similar elements as those in the covered arc welding system (see FIG. 1) according to the first embodiment are denoted by the same reference numerals. In FIG. 6, the control circuit 8 is illustrated in a simplified manner. As shown in FIG. 6, the welding power supply device A2 is different from the welding power supply device A1 according to the first embodiment in that the voltage superimposing circuit 6 is arranged on the output side of the inverter circuit 7.
　電圧重畳回路６は、インバータ回路７の出力側に配置されており、出力端子ｂ（被覆アーク溶接棒Ｂ）の電位を高くするように、出力端子ａ，ｂ間に再点弧電圧を重畳する構成になっている。放電回路６４は、スイッチング駆動信号（図５Ａ参照）がオンからオフに切り換わったとき（図５Ａ－Ｅにおける時刻ｔ１）に導通しており、出力電流（図５Ｂ参照）の極性が変わったとき（図５Ａ－Ｅにおける時刻ｔ２）に、再点弧コンデンサ６２が放電し、再点弧電圧が出力端子ａ，ｂ間に重畳される。 The voltage superimposing circuit 6 is disposed on the output side of the inverter circuit 7 and superimposes a re-ignition voltage between the output terminals a and b so as to increase the potential of the output terminal b (covered arc welding rod B). It is configured. The discharge circuit 64 is conductive when the switching drive signal (see FIG. 5A) switches from on to off (time t1 in FIGS. 5A to 5E), and the polarity of the output current (see FIG. 5B) changes. At time t2 in FIGS. 5A to 5E, the re-ignition capacitor 62 is discharged, and the re-ignition voltage is superimposed between the output terminals a and b.
　第２実施形態においては、よりアーク切れが発生しやすい、正極性から逆極性に切り換わるときに再点弧電圧を重畳できるので、アーク切れの発生を抑制することができる。また、第１実施形態と同様に、溶接電源装置Ａ２を小型軽量化することができる。さらに、本実施形態においては、比較的にアーク切れが発生しにくい、逆極性から正極性に切り換わるときには再点弧電圧を重畳させないので、第１実施形態と比べて、限流抵抗６４ｂでの損失を低減することができる。また、再点弧電圧を放電してから次に放電するまでの時間が長くなるので、再点弧電圧を充電するために時間がかかる場合に、特に有効である。 In the second embodiment, arc breakage is more likely to occur, and since re-ignition voltage can be superimposed when switching from positive polarity to reverse polarity, occurrence of arc breakage can be suppressed. Further, similarly to the first embodiment, the welding power source device A2 can be reduced in size and weight. Furthermore, in the present embodiment, arc break is relatively difficult to occur, and when the reverse polarity is switched to the positive polarity, the re-ignition voltage is not superimposed. Therefore, compared with the first embodiment, the current limiting resistance 64b Loss can be reduced. Further, since the time from discharge of the re-ignition voltage to the next discharge becomes longer, it is particularly effective when it takes time to charge the re-ignition voltage.
　本開示に係る被覆アーク溶接システムおよび被覆アーク溶接用の溶接電源装置は、上述した実施形態に限定されるものではない。本開示に係る被覆アーク溶接システムおよび被覆アーク溶接用の溶接電源装置の各部の具体的な構成は、種々に設計変更自在である。 The covering arc welding system and the welding power supply apparatus for covering arc welding according to the present disclosure are not limited to the above-described embodiments. The specific configuration of each part of the coated arc welding system and the welding power supply apparatus for the coated arc welding according to the present disclosure can be modified in various ways.

Claims (10)

  1. 　被覆アーク溶接棒と、
    　前記被覆アーク溶接棒に電力を供給する溶接電源装置と、を備え、
    　前記溶接電源装置は、
    　交流電力を整流する整流回路と、
    　前記整流回路の出力を平滑化する直流リアクトルと、
    　前記直流リアクトルが出力する直流電力を交流電力に変換して、前記被覆アーク溶接棒に出力するインバータ回路と、
    　前記被覆アーク溶接棒への出力に再点弧電圧を重畳する電圧重畳回路と、
    を備え、
    　前記電圧重畳回路は、前記インバータ回路の出力電流の極性が切り替わるときに、前記再点弧電圧を重畳する、被覆アーク溶接システム。     A coated arc welding rod;
    A welding power supply device for supplying power to the coated arc welding rod,
    The welding power source is
    A rectifier circuit for rectifying AC power;
    A DC reactor for smoothing the output of the rectifier circuit;
    An inverter circuit that converts the DC power output by the DC reactor into AC power and outputs the AC power to the coated arc welding rod;
    A voltage superimposing circuit for superimposing a re-ignition voltage on the output to the coated arc welding rod;
    With
    The said voltage superimposition circuit is a covering arc welding system which superimposes the said re-ignition voltage, when the polarity of the output current of the said inverter circuit switches.
  2. 　前記電圧重畳回路は、
    　前記再点弧電圧を充電される再点弧コンデンサと、
    　前記再点弧コンデンサに前記再点弧電圧を充電する充電回路と、
    　前記再点弧コンデンサに充電された前記再点弧電圧を放電する放電回路と、
    を備えており、
    　前記充電回路は、充電の開始または終了のタイミングが制御されている、
    請求項１に記載の被覆アーク溶接システム。     The voltage superimposing circuit is
    A re-ignition capacitor charged with the re-ignition voltage;
    A charging circuit for charging the re-ignition capacitor with the re-ignition voltage;
    A discharge circuit for discharging the re-ignition voltage charged in the re-ignition capacitor;
    With
    In the charging circuit, charging start or end timing is controlled,
    The coated arc welding system according to claim 1.
  3. 　前記インバータ回路の出力電流の瞬時値を検出する電流センサをさらに備えており、
    　前記充電回路は、前記電流センサが検出した電流瞬時値に基づいて、充電を開始する、請求項２に記載の被覆アーク溶接システム。     A current sensor for detecting an instantaneous value of the output current of the inverter circuit;
    The covering arc welding system according to claim 2, wherein the charging circuit starts charging based on an instantaneous current value detected by the current sensor.
  4. 　前記再点弧コンデンサの端子間電圧を検出する電圧センサをさらに備えており、
    　前記充電回路は、前記電圧センサが検出した前記端子間電圧に基づいて、充電を終了する、
    請求項２または３に記載の被覆アーク溶接システム。     A voltage sensor for detecting a voltage between terminals of the re-ignition capacitor;
    The charging circuit terminates charging based on the voltage between the terminals detected by the voltage sensor.
    The coated arc welding system according to claim 2 or 3.
  5. 　前記インバータ回路に駆動信号を出力する制御回路をさらに備えており、
    　前記放電回路は、前記駆動信号に基づいて、放電を制御する、
    請求項２ないし４のいずれかに記載の被覆アーク溶接システム。     A control circuit for outputting a drive signal to the inverter circuit;
    The discharge circuit controls discharge based on the drive signal.
    The coated arc welding system according to any one of claims 2 to 4.
  6. 　前記インバータ回路の出力電流の瞬時値を検出する電流センサをさらに備えており、
    　前記放電回路は、前記電流センサが検出した電流瞬時値に基づいて、放電を制御する、請求項２ないし４のいずれかに記載の被覆アーク溶接システム。     A current sensor for detecting an instantaneous value of the output current of the inverter circuit;
    The said discharge circuit is a covering arc welding system in any one of Claim 2 thru | or 4 which controls discharge based on the electric current instantaneous value which the said current sensor detected.
  7. 　前記インバータ回路の出力電流波形の制御目標を設定する波形目標設定部をさらに備えており、
    　前記放電回路は、前記制御目標に基づいて、放電を制御する、
    請求項２ないし４のいずれかに記載の被覆アーク溶接システム。     A waveform target setting unit for setting a control target of the output current waveform of the inverter circuit;
    The discharge circuit controls discharge based on the control target.
    The coated arc welding system according to any one of claims 2 to 4.
  8. 　前記電圧重畳回路は、前記被覆アーク溶接棒に出力する電流が負から正に切り替わるときにのみ、前記再点弧電圧を重畳する、
    請求項１ないし７のいずれかに記載の被覆アーク溶接システム。     The voltage superimposing circuit superimposes the re-ignition voltage only when the current output to the coated arc welding rod is switched from negative to positive.
    The coated arc welding system according to any one of claims 1 to 7.
  9. 　前記インバータ回路は、正弦波交流電流を出力する、請求項１ないし８のいずれかに記載の被覆アーク溶接システム。 The coated arc welding system according to any one of claims 1 to 8, wherein the inverter circuit outputs a sinusoidal alternating current.
  10. 　交流電力を整流する整流回路と、
    　前記整流回路の出力を平滑化する直流リアクトルと、
    　前記直流リアクトルが出力する直流電力を交流電力に変換して、被覆アーク溶接棒に出力するインバータ回路と、
    　前記被覆アーク溶接棒への出力に再点弧電圧を重畳する電圧重畳回路と、
    を備えており、
    　前記電圧重畳回路は、前記インバータ回路の出力電流の極性が切り替わるときに、前記再点弧電圧を重畳する、被覆アーク溶接用の溶接電源装置。     A rectifier circuit for rectifying AC power;
    A DC reactor for smoothing the output of the rectifier circuit;
    An inverter circuit that converts the DC power output by the DC reactor into AC power and outputs the AC power to the coated arc welding rod;
    A voltage superimposing circuit for superimposing a re-ignition voltage on the output to the coated arc welding rod;
    With
    The said voltage superimposition circuit is a welding power supply apparatus for clad arc welding which superimposes the said re-ignition voltage when the polarity of the output current of the said inverter circuit switches.
PCT/JP2018/008772 2017-04-04 2018-03-07 Shielded metal arc welding system and welding power supply device for shielded metal arc welding WO2018186098A1 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4827070B1 (en) * 1970-07-21 1973-08-18
JPH0237971A (en) * 1988-07-27 1990-02-07 Matsushita Electric Ind Co Ltd Ac arc welding power source
JPH03174974A (en) * 1989-11-30 1991-07-30 Daihen Corp Ac arc welding machine
JPH03180276A (en) * 1989-12-07 1991-08-06 Daihen Corp Ac arc welding machine
JP2010046692A (en) * 2008-08-22 2010-03-04 Daihen Corp Ac arc welding power source
JP2016144396A (en) * 2015-02-05 2016-08-08 リンカーン グローバル，インコーポレイテッド Circuits for improved welding performance

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4827070B1 (en) * 1970-07-21 1973-08-18
JPH0237971A (en) * 1988-07-27 1990-02-07 Matsushita Electric Ind Co Ltd Ac arc welding power source
JPH03174974A (en) * 1989-11-30 1991-07-30 Daihen Corp Ac arc welding machine
JPH03180276A (en) * 1989-12-07 1991-08-06 Daihen Corp Ac arc welding machine
JP2010046692A (en) * 2008-08-22 2010-03-04 Daihen Corp Ac arc welding power source
JP2016144396A (en) * 2015-02-05 2016-08-08 リンカーン グローバル，インコーポレイテッド Circuits for improved welding performance

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