JP5293882B2 - Arc welding equipment - Google Patents

Description

  The present invention relates to an arc welding apparatus that performs welding using a non-consumable electrode.

  In recent years, aluminum and magnesium materials, which are lightweight and highly recyclable, are widely used in buildings and vehicles in consideration of the environment. And many AC arc welding apparatuses are utilized for the joining. Note that the AC arc welding apparatus performs arc welding by alternately repeating reverse polarity and positive polarity (see, for example, Patent Document 1).

  In particular, at work sites that produce large buildings, welding work is performed with a large current in the range of 300 A or more and 500 A or less in order to increase work efficiency.

  In a conventional AC arc welding apparatus (for example, a TIG welding apparatus) that outputs such a large current, heat loss of a semiconductor that mainly operates inside the apparatus becomes large. Therefore, it is necessary to employ a semiconductor with a slow switching speed in order to reduce the on loss (product of the on-resistance of the main transistor and the energization current). As a result, the switching loss increases, so that the inverter frequency cannot be increased. Therefore, the circuit configuration operates at an inverter frequency of a relatively low frequency (for example, up to about 10 kHz). Accordingly, it is necessary to mount a reactor having a large inductance value in order to prevent arc breakage in a low current region (for example, up to about 10 A).

  FIG. 4 is a diagram showing a schematic configuration of a conventional arc welding apparatus, and FIG. 5 is a diagram showing a time change of a welding current waveform in the conventional arc welding apparatus. The operation of a conventionally used arc welding apparatus will be described with reference to FIGS. Hereinafter, a non-consumable electrode type AC arc welding apparatus that performs welding by alternately repeating a reverse polarity period and a positive polarity period will be described.

  In FIG. 4, the arc welding apparatus 22 includes a current detection unit 4 that detects a welding current, a high voltage generation unit 8, an output unit 19 that performs welding output, and a control unit 20 that controls the output unit 19. And a reactor 21 provided between the output unit 19 and the welding torch 10. Here, the high voltage generator 8 applies a high voltage between the electrode 9 provided in the welding torch 10 and the base material 12 as a welding object. In addition, a welding torch 10 provided with an electrode 9 and a base material 12 as a welding object are connected to the arc welding device 22, and an arc 11 is generated between the electrode 9 and the base material 12 to perform welding. I do.

  In FIG. 5 showing the time variation of the welding current and the high voltage generation signal, IP indicates a peak current value, and IS indicates a start current value. E1 indicates a welding start time that is a time when welding is started, and E2 indicates a current detection time that is a time when current is detected by the current detection unit 4. TUP3 indicates the rise time at the time of the conventional arc start, and TUP4 indicates the rise time at the time of the conventional steady welding. In addition, I3 has shown the electric current value before the polarity of a welding current commutates from positive polarity to reverse polarity.

  In FIG. 4, commercial power input (for example, using 200 V or the like) fed from an external device such as a switchboard is fed to the output unit 19 of the arc welding apparatus 22. The output unit 19 outputs a welding current and a welding voltage suitable for welding by inverter control driven at an inverter frequency of about 10 kHz based on the welding control signal output by the control unit 20. The welding current and welding voltage output from the output unit 19 are smoothed through the reactor 21 and supplied to the welding torch 10 and the base material 12, and an arc 11 is generated between the tip of the electrode 9 and the base material 12. AC arc welding is performed.

  When the inverter frequency is about 10 kHz, the inductance value of the reactor 21 needs to be 200 μH or more so that the arc does not break at a low current (for example, about 10 A). This inductance value is determined based on, for example, experiments and calculations.

  Here, the control unit 20 outputs a high voltage generation signal to the high voltage generation unit 8 to turn on the high voltage generation signal at the start of the arc start. Thereafter, the control unit 20 receives the current detection signal output from the current detection unit 4 and generates a high voltage when the current detection unit 4 detects the current and receives a signal indicating that the current detection unit 4 has detected the current. Turn off the signal.

  The high voltage generator 8 generates a voltage (for example, 15 kV) higher than the voltage at the time of steady welding, and between the electrode 9 and the base material 12 while the high voltage generation signal is on at the time of arc start. A high voltage is applied, and the application of the high voltage is stopped while the high voltage generation signal is off.

  Next, the time change of the welding current waveform in the conventional arc welding apparatus will be described with reference to FIG.

  At the welding start time point E <b> 1 at which welding is started, the control unit 20 turns on the drive of the output unit 19 and applies a no-load voltage between the electrode 9 and the base material 12 by the output unit 19. Further, the control unit 20 turns on the high voltage generation signal and applies a high voltage for arc start by the high voltage generation unit 8. Thereafter, at the current detection time point E2 when the arc is generated and the current detection unit 4 detects the current, the control unit 20 turns off the high voltage generation signal and stops the application of the high voltage.

  In the arc start, the welding current rises at 500 A / msec during the rise time TUP3 at the time of arc start and reaches a start current value IS (for example, 350 A).

  In the steady welding period, the welding current rises at 500 A / msec and reaches the absolute value IP (eg, 350 A) of the peak current during the rise time TUP4 from the zero crossing point when the polarity of the welding current commutates. .

  As described above, the rise of the welding current at the start of the arc and the rise of the welding current during the steady welding period are determined by the inductance value of the reactor 21. Here, the rise means an increase amount of the welding current per unit time until the peak current is reached.

  The current command for AC welding is generally in a pulse form, and it is generally considered that a larger rise is better so that the actual current waveform is in a pulse form.

  When a reactor having a large inductance value (for example, 200 μH or more) is mounted on the conventional arc welding apparatus 22, the ripple of the welding current is suppressed, which is effective in preventing arc breakage at a low current (for example, about 10 A). However, on the other hand, there is a problem that the rise of the welding current is delayed, that is, the inclination is small and gentle, and the arc start property is deteriorated. Even if a rectangular command is given as the current command, the rise of the performed welding current is slower than the commanded current waveform due to the inductance of the reactor. And the tendency becomes strong, so that an inductance value is large.

  In recent years, with the advent of a new inverter system, it is possible to increase the inverter frequency (for example, up to about 40 kHz) in a 500 A class non-consumable electrode type arc welding apparatus (for example, TIG welding apparatus) for large currents. is there.

  In a TIG welding apparatus driven by an inverter frequency of 40 kHz, current ripple is small, and arc breakage hardly occurs at a low current (for example, about 10 A). Therefore, a reactor having a small inductance value (for example, 100 μH or less) can be mounted.

  For example, when a reactor having an inductance value of 50 μH is mounted, the rise of current increases (for example, 1500 A / msec or more), and the arc start performance is dramatically improved.

  However, in the TIG welding apparatus having a large current rise (1500 A / msec or more), the current rise during steady welding is also large (1500 A / msec or more). As a result, it was found that the filler wire could not be melted smoothly during the work of inserting the filler wire during construction with a large current (for example, 300 A or more), resulting in poor workability.

  That is, when a reactor having a small inductance value is used, the arc start performance is improved, but workability during steady welding is deteriorated.

JP-A-2-235574

  The present invention provides an arc welding apparatus that has good arc start performance and good workability of a filler wire during high current welding.

  An arc welding apparatus according to the present invention is a non-consumable electrode type arc welding apparatus that performs welding by outputting an AC pulse having an absolute value of a peak current of 300 A or more and 1500 A or less, and outputs an welding current. And a control unit that outputs a welding current control signal for each cycle of the welding current controlled with respect to the output unit, and a reactor whose inductance value is 10 μH or more and 100 μH or less, and the control unit includes: At the time of arc start, the first rise time until the welding current reaches the absolute value of the peak current after the start of the arc start, and the polarity of the welding current at the time of steady welding after the arc start The second rise time from the time of zero crossing until reaching the absolute value of the peak current, and the second rise time is the first rise time. The welding current is controlled to be longer than the time.

  With this configuration, an arc welding apparatus that improves arc start performance during large current construction, does not deteriorate workability in the work of inserting the filler wire, and enables good workability to smoothly melt the filler wire is provided. be able to.

The figure which shows schematic structure of the arc welding apparatus in Embodiment 1 of this invention. The figure which shows the time change of the welding current waveform in Embodiment 1 of this invention. The figure which shows the correlation between the welding current value in Embodiment 1 of this invention, and the increase amount of the welding current value per unit time of welding current. The figure which shows schematic structure of the conventional arc welding apparatus The figure which shows the time change of the welding current waveform in the conventional arc welding apparatus

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same components are denoted by the same reference numerals, and the description thereof may be omitted.

(Embodiment 1)
FIG. 1 is a diagram showing a schematic configuration of an arc welding apparatus in the present embodiment, and FIG. 2 is a diagram showing a time change of a welding current waveform in the present embodiment. FIG. 3 is a diagram showing a correlation between the welding current value and the increase amount of the welding current value per unit time of the welding current in the present embodiment. About the arc welding apparatus comprised like FIG. 1, the operation | movement is demonstrated using FIG. 2 and FIG.

  Hereinafter, a non-consumable electrode type AC arc welding apparatus that performs welding by alternately repeating a reverse polarity period and a positive polarity period will be described as an example.

  In FIG. 1, an arc welding apparatus 1 includes an output unit 2 that performs welding output, a control unit 3, a current detection unit 4 that detects a welding current, a reactor 5 that smoothes the output of the output unit 2, and a storage unit 6. And a selection unit 7 for selecting the storage contents of the storage unit 6 and a high voltage generation unit 8 for outputting a high voltage. Here, the control unit 3 controls the output unit 2 by outputting a control signal to the output unit 2 every control cycle. The storage unit 6 stores an increase amount of the welding current value per unit time of the welding current with respect to the welding current value.

  The output unit 2 includes a rectification unit 14, a smoothing unit 15, an inverter control unit 13, a transformer 16, a secondary rectification unit 17, and a secondary inverter control unit 18. Here, the smoothing unit 15 smoothes the output of the rectifying unit 14. The inverter control unit 13 performs inverter control on the output of the smoothing unit 15. The transformer 16 transforms the output of the inverter control unit 13. The secondary rectifier 17 smoothes the output of the transformer 16. The secondary inverter control unit 18 performs inverter control on the output of the secondary rectification unit 17.

  Moreover, the arc welding apparatus 1 is connected to a welding torch 10 provided with an electrode 9 and a base material 12 as a welding object via cables 10a and 12a. Then, the arc welding apparatus 1 performs welding by generating an arc 11 between the electrode 9 and the base material 12 by supplying electric power between the electrode 9 and the base material 12.

  In FIG. 2 showing the time change of the welding current and the like, IP indicates the peak current value of the welding current, and IS indicates the start current value of the welding current. I1 is a current value during the rise, indicating a first current value smaller than the peak current IP, and I2 is a current value during the fall, indicating a second current value smaller than the peak current IP. Yes.

  TUP1 indicates a first rise time that is a time from when the welding current reaches zero to the start current IS, and TUP2 reaches the peak current IP from when the welding current commutates to zero. The 2nd rise time which is time until is shown. TDN1 indicates a first fall time that is a time until the peak current IP decreases to the second current value I2, and TH indicates a predetermined time that is a period during which the second current value I2 is maintained. Yes. TDN2 indicates a second fall time that is a time obtained by adding the first fall time TDN1 and the predetermined time TH.

  DI1 indicates an increase amount of the welding current value per unit time of the first welding current, and DI2 indicates an increase of the welding current value per unit time of the second welding current different from the first welding current. Indicates the amount.

  Further, E1 indicates a welding start time that is a time when welding is started, E2 indicates a current detection time that is a time when current is detected, and E3 indicates an arc start completion time that is a time when the arc start period is completed. Is shown.

  In FIG. 1, a commercial power input (for example, 200 V) fed from an external device such as a switchboard is fed to the output unit 2 of the arc welding apparatus 1. Then, it is converted into a DC voltage by the rectifying unit 14 constituted by a diode or the like and the smoothing unit 15 constituted by an electrolytic capacitor or the like. And the current detection part 4 comprised by CT (Current Transformer) etc. detects a welding current. The output of the current detection unit 4 is input to the control unit 3 including a CPU, a DSP (Digital Signal Processor), an ADC (Analog to Digital Converter), and the like. Then, the control unit 3 creates an output command suitable for welding in synchronization with the control timing of the inverter (for example, the switching operation timing of the inverter), performs current feedback calculation based on the output target, and performs switching of the inverter control unit 13. The conduction width of the element is calculated and a welding current control signal is output.

  And based on the welding current control signal which the control part 3 outputs, IGBT (Insulated Gate Bipolar Transistor) driven by PWM (Pulse Width Modulation) operation | movement and phase shift operation | movement, MOSFET (Metal-Oxide Semiconductor Field Transistor etc.). The inverter control unit 13 is driven by an inverter, and converts the DC voltage converted by the rectifying unit 14 and the smoothing unit 15 into a high-frequency AC voltage suitable for welding via the transformer 16.

  In addition, the no-load voltage which the transformer 16 outputs is 80V. The transformer 16 operates at 40 kHz as an inverter frequency. The inverter includes an IGBT and a transformer, and operates at a transformer current frequency of 40 kHz.

  Then, the high-frequency AC voltage output from the transformer 16 is rectified by the secondary rectification unit 17 configured by a diode or the like and input to the secondary inverter control unit 18. The secondary inverter control unit 18 is configured by a circuit such as a full bridge or a half bridge using an IGBT or the like, and switches output polarity between positive polarity and reverse polarity.

  Here, the positive polarity means a case where the moving direction of the electrons in the arc plasma is a direction from the electrode 9 toward the base material 12, the electrode 9 is negative, and the base material is positive. Reverse polarity refers to the case where the moving direction of electrons in the arc plasma is the direction from the base material 12 toward the electrode 9, the electrode 9 is positive, and the base material 12 is negative.

  The welding current and welding voltage output by the secondary inverter control unit 18 are smoothed through the reactor 5 and supplied to the welding torch 10. Then, an arc 11 is generated between the tip of the electrode 9 made of tungsten, which is a non-consumable electrode, and the base material 12, which is a welding object such as an aluminum material, and AC arc welding is performed.

  The inductance value of the reactor 5 is 100 μH or less, for example, 50 μH, and the inductance value is smaller than that of the reactor 21 provided in the conventional arc welding apparatus 22 described with reference to FIG. Thereby, the increase amount of the welding current value per unit time of the welding current can be set to 1500 A / msec.

  Moreover, the memory | storage part 6 comprised with CPU etc. is the per unit time of the 1st welding current shown in FIG. 3 as an increase amount of the welding current value per unit time of different welding current with respect to the same welding current value. The increase amount of the welding current and the increase amount of the welding current per unit time of the second welding current are stored. It should be noted that the increase amount of the welding current per unit time of the welding current may be stored not three but three or more.

  Moreover, the selection part 7 comprised by CPU etc. is the increase amount of the welding current value per unit time of one welding current from the increase amount of the welding current value per unit time of the some welding current memorize | stored in the memory | storage part 6. Is input to the control unit 3. The selection unit 7 may be switched automatically according to welding current setting, frequency setting, and welding method setting. Or you may make it switch manually according to the liking of the operator who operates the arc welding apparatus 1. FIG.

  The control unit 3 performs output control by outputting a control signal to the output unit 2 based on the increase amount of the welding current value per unit time of the welding current selected and output by the selection unit 7. Further, the control unit 3 can also output a high voltage generation signal to the high voltage generation unit 8, and when the arc start is started by pressing a torch switch (not shown) provided in the welding torch 10, the high voltage generation signal is output. Turn on and output to high voltage generator 8. Then, an arc is generated between the electrode 9 and the base material 12 due to the high voltage output from the high voltage generator 8, and a current flows. When a current detection signal is received from the current detector 4 that detects this current, The voltage generation signal is turned off, and the output of the high voltage generator 8 is stopped.

  While the high voltage generation signal output from the control unit 3 is on, the high voltage generation unit 8 composed of a flyback transformer or the like applies a voltage (for example, 15 kV) higher than the voltage during steady welding to the electrode 9 and the mother. Applied between the material 12. On the other hand, while the high voltage generation signal output from the control unit 3 is off, the application of the high voltage is stopped.

  Next, the time change of the welding current waveform from the start of welding in the arc start period to the rise of the AC welding current pulse during steady welding in the steady welding period after the arc start period will be described with reference to FIG.

  At the welding start time point E <b> 1 at which welding is started, the control unit 3 turns on the drive of the inverter control unit 13 and applies a no-load voltage (for example, 80 V) between the electrode 9 and the base material 12. Further, the control unit 3 applies a high voltage (for example, 15 kV) for arc start between the electrode 9 and the base material 12 by turning on the high voltage generation signal and outputting it to the high voltage generation unit 8. To do. Then, at the current detection time point E2 when the arc is generated by this high voltage and a welding current flows and the current detection unit 4 detects the current, the control unit 3 turns off the high voltage generation signal and generates a high voltage. By outputting to the unit 8, the application of the high voltage is stopped.

  At the time of arc start, during the first rise time TUP1 (for example, 0.23 msec), the welding current rises at an increase in the welding current per unit time of 1500 A / msec, and the start current value IS (for example, 350A).

  Thereafter, at the arc start period completion time point E3 when the arc start period is completed, the arc start period is shifted to the steady welding period. Note that the completion of the arc start period may be the time when a preset time (for example, 100 msec) has elapsed since the arc start. In addition, the completion of the arc start period may be the time when, for example, five pulses of AC output are performed when the number of times of output of AC pulses is measured and the pulses are output a predetermined number of times.

  Further, during the steady welding period, commutation in which the positive polarity and the reverse polarity are changed is performed, and the welding current is a second rise time TUP2 (for example, 0.85 msec from the zero crossing point when the polarity of the welding current is commutated). ) And the peak current IP (for example, 350 A) is reached.

  Note that, during the period of the second rise time TUP2, the welding current rises with the increase amount of the welding current per unit time being 500 A / msec until it reaches the first current value I1 (for example, 50 A). And after exceeding 1st electric current value I1 (for example, 50A), it is smaller than 500 A / msec, and the increase amount of the welding current value per unit time becomes so small that the absolute value of welding current becomes high. stand up. For example, the absolute value of the welding current is based on the increase amount of the welding current per unit time of the first welding current indicated by a solid line in FIG.

  As described above, with the reactor 5 having a small inductance value connected, at the time of arc start, the welding current is sharply raised by the rise of the welding current depending on the inductance value of the reactor 5 to ensure the arc start performance. At the same time, the filler wire workability is improved by giving a welding current command and controlling so that the rise of the welding current becomes gentler than that at the time of arc start during steady welding without depending on the inductance value of the reactor 5. Can be.

  Note that, during the second rise time TUP2, the amount of increase in the welding current per unit time rises at 1500 A / msec instead of 500 A / msec until the first current value I1 (for example, 50 A) is reached. After exceeding the first current value I1 (for example, 50 A), the control may be performed such that the increase in the welding current value per unit time decreases as the absolute value of the welding current increases.

  Here, 1500 A / msec is assumed to be the maximum amount of change per unit time that can be output by the arc welding apparatus 1 determined by the inductance value of the reactor 5. Thus, the welding current may be increased by the maximum amount of change per unit time in the initial period of increase in current.

  That is, the arc welding apparatus 1 of the present invention is a non-consumable electrode type arc welding apparatus that performs welding by outputting an AC pulse having an absolute value of a peak current of 300 A or more and 1500 A or less. The arc welding apparatus 1 includes an output unit 2 that outputs a welding current, a control unit 3 that outputs a welding current control signal for each cycle of the welding current to be controlled, and an inductance value of 10 μH. As described above, the reactor 5 is 100 μH or less. The control unit 3 of the arc welding apparatus 1 uses the first rise time TUP1 and the second rise time TUP2 to perform welding so that the second rise time TUP2 is longer than the first rise time TUP1. The current is controlled. Here, the first rise time TUP1 is a time from when the welding current starts the arc start until the absolute value of the peak current is reached at the time of the arc start. The second rise time TUP2 is the time from the zero cross point when the polarity of the welding current commutates during steady welding after the arc start until the absolute value of the peak current is reached.

  With this configuration, there is provided an arc welding apparatus 1 that improves arc start performance during large-current construction, does not deteriorate workability in the work of inserting a filler wire, and enables good workability to melt the filler wire smoothly. can do.

  The control unit 3 may be configured to control the welding current that increases during the second rise time TUP2 such that the increase in the welding current value per unit time decreases as the absolute value of the welding current increases.

  With this configuration, during steady welding, the welding current command is given and controlled so that the rise of the welding current becomes gentler than the arc start without depending on the inductance value of the reactor 5, so that the work of the filler wire Can be improved.

  Further, the controller 3 increases the welding current that increases during the second rise time TUP2 without changing the increase in the welding current value per unit time until the first current value I1 is reached. When the current value I1 is exceeded, the control may be performed such that the increase in the welding current value per unit time decreases as the absolute value of the welding current increases.

  With this configuration, at the time of arc start, the welding current rises sharply by the rise of the welding current depending on the inductance value of the reactor 5 to ensure the arc start performance, and at the time of steady welding, the workability of the filler wire is improved. Can be good.

  Further, the output unit can output a welding current of 1000 A / msec or more and 10,000 A / msec or less as an increase amount of the welding current per unit time. The increase amount of the welding current per unit time in the first rise time TUP1 is 1000 A / ms or more and 10000 A / msec or less, and the increase amount of the welding current per unit time in the second rise time TUP2 is 10 A. / Msec or more and 500 A / msec or less.

  With this configuration, at the time of arc start, the welding current rises sharply by the rise of the welding current depending on the inductance value of the reactor 5 to ensure the arc start performance, and at the time of steady welding, the workability of the filler wire is improved. Can be good.

  Further, the output unit can output a welding current of 1000 A / msec or more and 10,000 A / msec or less as an increase amount of the welding current per unit time. And the increase amount of the welding current per unit time in 1st rise time TUP1 is 1000 A / msec or more and 10000 A / msec or less. The amount of increase in the welding current per unit time until reaching the first current value I1 during the second rise time TUP2 is 1000 A / msec or more and 10000 A / msec or less. The increase amount of the welding current per unit time when the first current value I1 during the second rise time TUP2 is exceeded may be 10 A / msec or more and 500 A / msec or less.

  With this configuration, at the time of arc start, the welding current rises sharply by the rise of the welding current depending on the inductance value of the reactor 5 to ensure the arc start performance, and at the time of steady welding, the workability of the filler wire is improved. Can be good.

  Moreover, the output part 2 is provided with the inverter control part 13, and the inverter frequency of the inverter control part 13 is good also as a structure which is 40 kHz or more and 1 MHz or less.

  With this configuration, the current ripple is further reduced, and arc breakage hardly occurs at a low current (for example, about 10 A).

  In addition, a high voltage generator 8 is provided between the non-consumable electrode and the welding object between the non-consumable electrode and the welding object. A configuration may be adopted in which an arc start is performed by applying a high voltage.

  With this configuration, a better arc start can be realized, and the base material and the electrode are not damaged during the arc start.

  As described above, by increasing the rise of the welding current in the vicinity of the zero crossing point at the time of commutation, it is possible to prevent arc breakage from occurring at the time of commutation. In the conventional arc welding apparatus 22 described with reference to FIG. 4, since the rise of current near the zero cross is determined by the inductance value of the reactor 21, the rise near the zero cross cannot be increased.

  Next, the time change of the welding current waveform at the time when the welding current falls before commutation will be described with reference to FIG.

  The control unit 3 reduces the welding current during steady welding from the peak current value IP (for example, 350 A) to the second current value I2 (for example, 100 A) at a welding current reduction amount of 800 A / msec per unit time. The second current value I2 is controlled to be commutated after being maintained for a predetermined time (for example, 0.1 msec). Note that the first fall time TDN1 (for example, 0.32 msec) until the peak current value IP is reduced to the second current value I2 is shorter than the second rise time TUP2 (for example, 0.85 msec). Control to be. Further, during steady welding, a second falling time TDN2 (for example, 0.42 msec) from when the welding current starts to decrease from the peak welding current IP to when the zero crossing point when the polarity of the welding current commutates is reached. , Control may be performed so as to be shorter than the second rise time TUP2.

  As described above, the second current value I2, which is the current value before commutation, is increased by increasing the amount of decrease in the current fall, and the commutation in the conventional arc welding apparatus 22 described with reference to FIG. It can be set lower than the previous current value I3 (for example, 200 A). Thereby, it is possible to prevent the semiconductor element from being damaged by a high surge voltage generated due to switching of the semiconductor constituting the secondary inverter at the time of commutation.

  Further, the current value I3 before commutation of the conventional arc welding apparatus 22 described with reference to FIG. 5 is determined by the inductance value of the reactor 21 shown in FIG. 4, and is determined by the amount of decrease in the current fall. Therefore, the current could not be dropped sharply before commutation.

  Next, with reference to FIG. 2, a welding current waveform when a plurality of welding current increasing amounts per unit time of a welding current are provided and they are switched will be described.

  The storage unit 6 of the arc welding apparatus 1 stores the welding current per unit time of the first welding current shown in FIG. 3 as an increase amount of the welding current value per unit time of different welding currents for the same welding current value. And an increase amount of the welding current per unit time of the second welding current are stored. And the selection part 7 switches and selects the memory content of the memory | storage part 6. FIG.

  In the example shown in FIG. 3, the decrease degree of the increase amount of the welding current per unit time of the second welding current is larger than the increase amount of the welding current per unit time of the first welding current.

  Consider the case where the selection unit 7 selects the increase amount of the welding current per unit time of the first welding current. At this time, the rise of the welding current during the second rise time TUP2 rises with a slope indicated by the increase amount DI1 of the welding current per unit time of the first welding current shown in FIG. On the other hand, consider a case where the selection unit 7 selects the amount of increase in the welding current per unit time of the second welding current. At this time, the rise of the welding current during the second rise time TUP2 rises with a slope of the increase amount DI2 of the welding current per unit time of the second welding current shown in FIG.

  The degree of decrease in the increase amount of the welding current per unit time of the second welding current is larger than the increase amount of the welding current per unit time of the first welding current. From this, it can be seen that the welding current of the increasing amount DI2 of the welding current per unit time of the second welding current in FIG. 2 rises more gently. When the rising waveform of the welding current becomes gentle, the arc spreads and the workability of the filler wire is improved. On the other hand, it tends to be difficult for fillet welding due to concentration. Therefore, it is desirable to memorize each suitable rise based on the welding object, welding conditions, etc., and to perform welding by selecting the suitable rise.

  As described above, by enabling the selection unit 7 to switch the increase amount of the welding current value per unit time of the welding current, it is possible to control the rising of the welding current during the second rising time TUP2. Thereby, workability | operativity of a filler wire can be adjusted and it becomes possible to respond | correspond to various construction conditions and the preference by an operator.

  In the arc welding apparatus of the present invention, the control unit 3 reduces the welding current at the time of steady welding from the peak current value IP to the second current value I2 smaller than the peak current value IP, and this second current value I2. Is controlled to commutate after maintaining TH for a predetermined time. The control unit 3 is configured to control the first fall time TDN1 until the peak current value IP is reduced to the second current value I2 to be shorter than the second rise time TUP2.

  With this configuration, the amount of decrease in current fall can be increased, and the second current value I2, which is the current value before commutation, can be set lower than the current value I3 before commutation in the conventional arc welding apparatus 22. . Thereby, it is possible to prevent the semiconductor element from being damaged by a high surge voltage generated due to switching of the semiconductor constituting the secondary inverter at the time of commutation.

  In addition, the control unit 3 sets the second fall time TDN2 until the zero crossing time when the polarity of the welding current commutates from the peak welding current IP during the steady welding from the second rise time TUP2. Is controlled to be shorter.

  With this configuration, the amount of decrease in current fall can be increased, and the second current value I2, which is the current value before commutation, can be set lower than the current value I3 before commutation in the conventional arc welding apparatus 22. . Thereby, it is possible to prevent the semiconductor element from being damaged by a high surge voltage generated due to switching of the semiconductor constituting the secondary inverter at the time of commutation.

  Further, the output unit 2 can reduce a welding current of 800 A / msec or more and 10000 A / msec or less as a reduction amount of the welding current per unit time, and the welding current per unit time in the first fall time TDN1. Or a decrease amount of the welding current per unit time in the second fall time TDN2 is 800 A / msec or more and 10,000 A / msec or less.

  With this configuration, the amount of decrease in current fall can be increased, and the second current value I2, which is the current value before commutation, can be set lower than the current value I3 before commutation in the conventional arc welding apparatus 22. . Thereby, it is possible to prevent the semiconductor element from being damaged by a high surge voltage generated due to switching of the semiconductor constituting the secondary inverter at the time of commutation.

  Further, a storage unit 6 that stores a plurality of increments of welding current values per unit time of different welding currents for the same welding current value, and a welding current per unit time of the plurality of welding currents stored in the storage unit 6 And a selector 7 for selecting an increase amount of the welding current value per unit time of one welding current from the increase amount of the value.

  With this configuration, the selection unit 7 can switch the increase amount of the welding current value per unit time of the welding current, whereby the rising of the welding current during the second rising time TUP2 can be controlled. Thereby, workability | operativity of a filler wire can be adjusted and it becomes possible to respond | correspond to various construction conditions and the preference by an operator.

  In FIG. 2, the peak current value IP has been described as the same value on the positive polarity side and the reverse polarity side, but may be different values.

  Also, the current increase amount decrease curve as shown in FIG. 3 may decrease linearly (primary expression) or non-linearly according to a polynomial expression (for example, quadratic expression).

  Further, the lower limit may be set (set a minimum value) with an arbitrary value (for example, 50 A / msec), and an intermediate point may be provided as necessary to bend the degradation characteristic nonlinearly.

  In addition, in FIG. 2, although the arc start demonstrated and demonstrated the example which starts from a reverse polarity side, you may start an arc from the positive polarity side.

  In FIG. 2, the start current value IS and the peak current value IP have been described as being the same value, but may be different values. In this case, the first rise time TUP1 may be converted to TUP1 = (TUP1 before conversion) × IS / IP based on the ratio between the start current value IS and the peak current value IP.

  In the present embodiment, an example in which high-frequency start is performed using the high voltage generator 8 at the time of arc start has been described, but touch start may be used.

  In the present embodiment, AC arc welding has been described. However, the present invention may be applied to a pulse rising waveform in DC non-consumable electrode arc welding.

  Further, the increase amount of the welding current per unit time of the welding current at the time of the rise of the welding current is different in this embodiment, although the same decrease curve is used on the positive polarity side and the reverse polarity side. You may make it use a characteristic.

  In addition, the increase amount of the welding current per unit time of the welding current at the time of rising of the welding current has been described with reference to FIG. 2 as an example of switching during welding, but is set before the arc start and fixed during welding. May be.

  Moreover, although the positive current and the reverse polarity peak current values have been described as arbitrary fixed values in FIG. 2, they may be welding current waveforms that fluctuate during the peak period.

  Finally, the relationship between the peak current value of the welding current and the workability of welding is shown in Table 1 below. In the table, ◯ indicates that workability is good, and X indicates that workability is poor. A triangle indicates that workability is slightly poor.

  As described above, according to the present embodiment, it is possible to improve the arc start performance and the workability of welding during steady welding.

  As described above, according to the present invention, even when a reactor having a small inductance value of 100 μH or less is mounted and the current start at the time of arc start is increased to improve the arc start performance, the second rise time is the first rise time. The welding current is controlled to be longer than the time. This control can provide an arc welding apparatus that has good workability without deteriorating workability in the work of inserting the filler wire even during large current construction.

  As described above, the present invention can provide an arc welding apparatus having good workability without deteriorating workability in an operation of inserting a filler wire even during large current construction. As a result, the arc welding apparatus of the present invention is industrially useful as an arc welding apparatus in an industry that performs arc welding construction, for example, a large-sized aluminum member such as the plant construction industry, which is welded at a large current and produced. It is.

DESCRIPTION OF SYMBOLS 1 Arc welding apparatus 2 Output part 3 Control part 4 Current detection part 5 Reactor 6 Memory | storage part 7 Selection part 8 High voltage generation part 9 Electrode 10 Welding torch 10a, 12a Cable 11 Arc 12 Base material 13 Inverter control part 14 Rectification part 15 Smoothing Part 16 Transformer 17 Secondary rectifier 18 Secondary inverter controller

Claims (11)

A non-consumable electrode type arc welding apparatus for performing welding by outputting an AC pulse having an absolute value of a peak current of 300 A or more and 1500 A or less,
An output section for outputting a welding current;
A control unit that outputs a welding current control signal for each cycle of the welding current to be controlled with respect to the output unit;
A reactor having an inductance value of 10 μH or more and 100 μH or less,
In the arc start, the control unit has a first rise time from when the welding current starts the arc start until the absolute value of the peak current is reached, and the polarity of the welding current during steady welding after the arc start. And the second rise time until the absolute value of the peak current is reached from the time of zero crossing at the time of commutation, the welding current so that the second rise time is longer than the first rise time. Arc welding equipment to control. The said control part controls the said welding current which increases during the said 2nd rise time so that the increase in the welding current value per unit time becomes so small that the absolute value of the said welding current becomes high. Arc welding equipment. The control unit increases the welding current that increases during the second rise time without changing the increase in the welding current value per unit time until the first current value is reached. 3. The arc welding apparatus according to claim 2, wherein when the current value is exceeded, control is performed such that the increase in the welding current value per unit time decreases as the absolute value of the welding current increases. The output unit can output a welding current of 1000 A / msec or more and 10000 A / msec or less as an increase amount of the welding current per unit time, and an increase amount of the welding current per unit time in the first rise time. 2. The arc welding apparatus according to claim 1, wherein 1000 A / msec to 10,000 A / msec, and an increase in welding current per unit time in the second rise time is 10 A / msec to 500 A / msec. . The output unit can output a welding current of 1000 A / msec or more and 10,000 A / msec or less as an increase amount of the welding current per unit time, and an increase amount of the welding current per unit time in the first rise time is It is 1000 A / msec or more and 10000 A / msec or less, and the increase amount of the welding current per unit time until the first current value during the second rise time is 1000 A / msec or more and 10000 A / msec or less. The arc welding apparatus according to claim 3, wherein an increase amount of the welding current per unit time when the first current value is exceeded during the second rise time is 10 A / msec or more and 500 A / msec or less. The control unit reduces the welding current at the time of steady welding from a peak current value to a second current value smaller than the peak current value, and maintains the second current value for a predetermined time so as to perform commutation. 2. The arc welding apparatus according to claim 1, wherein control is performed so that a first fall time until the peak current value is reduced to the second current value is shorter than the second rise time. The control unit causes the second fall time until reaching the zero crossing time when the polarity of the welding current is commutated from the peak welding current during the steady welding to be shorter than the second rise time. The arc welding apparatus according to claim 1, wherein The output unit can reduce a welding current of 800 A / msec or more and 10,000 A / msec or less as a reduction amount of the welding current per unit time, and a decrease in the welding current per unit time in the first fall time. The arc welding apparatus according to any one of claims 6 and 7, wherein a decrease amount of the welding current per unit time in the second fall time is 800 A / msec or more and 10000 A / msec or less. . A storage unit that stores a plurality of increments of welding current values per unit time of different welding currents for the same welding current value, and an increase in the welding current value per unit time of the plurality of welding currents stored in the storage unit The arc welding apparatus according to claim 1, further comprising: a selection unit that selects an increase amount of the welding current value per unit time of one welding current from the amount. The arc welding apparatus according to claim 1, wherein the output unit includes an inverter control unit, and an inverter frequency of the inverter control unit is 40 kHz or more and 1 MHz or less. A high voltage generator for applying a high voltage higher than the voltage during steady welding is provided between the non-consumable electrode and the welding object at the time of arc start, and a high voltage is provided between the non-consumable electrode and the welding object. The arc welding apparatus according to claim 1, wherein an arc start is performed by applying a voltage.

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