JP2021053695A - Welding system - Google Patents

Abstract

To provide a welding system that can freely shift timing at which positive and negative currents of alternating currents which a plurality of welding power supply devices output are switched, and enables the timing to match each other accurately.SOLUTION: A welding system A1 for performing submerged-arc welding comprises: a plurality of welding power supply devices 2a, 2b, 2c and 2d which have inverter circuits 25 respectively and output alternating-current power which the inverter circuits 25 generate; a control device 1 that controls the plurality of welding power supply devices 2a, 2b, 2c and 2d; a communication wire 31 through which command values for commanding respective outputs of the plurality of welding power supply devices 2a, 2b, 2c and 2d are transmitted from the control device 1 to the devices; and a communication wire 32 through which communication at higher speed than that through the communication wire 31 can be performed and through which synchronization signals for signalling timing for switching positive and negative currents of the alternating currents are transmitted from the control device 1 to the plurality of welding power supply devices 2a, 2b, 2c and 2d.SELECTED DRAWING: Figure 1

Description

The present invention relates to a welding system for performing submerged arc welding.

Submerged arc welding has been known conventionally. In submerged arc welding, flux on grains is sprayed on the work piece, and the welding wire is sent into the flux to generate an arc between the tip of the welding wire and the work piece to perform welding. It is what you do. In submerged arc welding, a thick plate can be welded with high efficiency by passing a large current through a large-diameter welding wire. Patent Document 1 discloses an example of a submerged arc welding apparatus for performing submerged arc welding.

AC power is supplied from the welding power supply device between the tip of the welding wire (hereinafter, may be referred to as "electrode") and the object to be welded. The welding power supply device is equipped with a transformer, and outputs AC power obtained by transforming AC power input from a commercial power source with a transformer. When a large current (for example, 2000A) is required for welding, it is difficult to output with one welding power supply device, so it is conceivable to connect a plurality of welding power supply devices in parallel. In this case, since the alternating current output from each welding power supply device is synchronized with the alternating current of the commercial power supply, the timing of switching between positive and negative is the same. Therefore, the circulating current does not occur due to the timing of switching between the positive and negative of the output AC current.

JP-A-2007-90410

On the other hand, in the case of multi-pole submerged arc welding, the plurality of electrodes are supplied with AC power from different welding power supplies. Then, in order to prevent the arcs generated by the adjacent electrodes from attracting each other, each welding power supply device outputs the AC current at different timings. When connected to a three-phase commercial power source, the welded power supply is 120 ° or 240 ° out of phase, depending on which two-phase it is connected to. However, the phase to be shifted is fixed to a predetermined phase, and each welding power supply device cannot shift the output AC current by a desired phase. Therefore, each welding power supply device cannot freely shift the timing of switching between positive and negative.

The present invention has been conceived under the above circumstances, and it is possible to freely shift the timing at which the positive and negative of the alternating current output by the plurality of welding power supply devices are switched, and the timing is exactly the same. It is an object of the present invention to provide a welding system which can also be used.

The welding system provided by the present invention is a welding system for performing submerge arc welding, each of which has an inverter circuit, and a plurality of welding power supply devices that output AC power generated by the inverter circuit. , A control device that controls the plurality of welding power supply devices, a first communication line that transmits a command value for commanding each output from the control device to the plurality of welding power supply devices, and the first communication line. It is provided with a second communication line that performs higher-speed communication and transmits a synchronization signal instructing the timing of switching between positive and negative alternating current from the control device to the plurality of welding power supply devices.

In a preferred embodiment of the present invention, the control device transmits delay information for delaying the timing to each of the welding power supply devices via the first communication line, and each welding power supply device receives the delay information. Each has a delay unit that delays the synchronization signal according to the delay information, and switches the positive and negative of the output AC current according to the synchronization signal delayed by the delay unit.

In a preferred embodiment of the present invention, the output sides of the welding power supply devices are connected in parallel to each other, and the delay information transmitted to the welding power supply devices is the same.

In a preferred embodiment of the present invention, the control device transmits a DC output command signal for outputting DC power to each of the welding power supply devices via the first communication line, and each of the welding is performed. When the power supply device receives the DC output command signal, it stops switching of the inverter circuit and outputs DC power.

In a preferred embodiment of the present invention, one of the plurality of welding power supply devices also serves as the control device.

According to the present invention, each welding power supply device can freely set the timing at which the positive / negative of the output AC current is switched by adjusting the switching of the inverter circuit. In addition, the control device transmits a synchronization signal to a plurality of welding power supply devices via a relatively high-speed second communication line. By adjusting the switching of the inverter circuit according to the received synchronization signal, each welding power supply device can accurately match the timing at which the positive / negative of the output AC current is switched with the others. In addition, each welding power supply device delays the received synchronization signal and adjusts the switching of the inverter circuit according to the synchronization signal after the delay, so that the timing at which the positive / negative of the output AC current is switched can be delayed compared to the others. it can. That is, each welding power supply device can freely shift the timing at which the positive / negative of the output AC current is switched.

It is a figure for demonstrating the welding system which concerns on 1st Embodiment, (a) is a block diagram which shows the whole structure of a welding system, and (b) is a block diagram which shows the internal structure of a welding power supply device. FIG. 5 is a waveform diagram showing a waveform of an alternating current output by each welding power supply device in the welding system according to the first embodiment. It is a block diagram which shows the whole structure of the welding system which concerns on 2nd Embodiment. FIG. 5 is a waveform diagram showing a waveform of an alternating current output by each welding power supply device in the welding system according to the second embodiment. It is a block diagram which shows the whole structure of the modification of the welding system which concerns on 1st Embodiment.

Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a diagram for explaining a welding system according to the first embodiment. FIG. 3A is a block diagram showing the overall configuration of the welding system. FIG. 3B is a block diagram showing an internal configuration of a welding power supply device.

The welding system A1 is a welding system for performing submerged arc welding. As shown in FIG. 1A, the welding system A1 includes a control device 1, a welding power supply device 2a, 2b, 2c, 2d, communication lines 31, 32, a trolley 4, a wire feeding device 5, a wire reel 6, and a hopper. 7 and an electrode 8 are provided. The welding system A1 disperses the flux on the grains from the hopper 7 while moving the carriage 4 along the welding line of the object W to be welded, and causes the wire feeding device 5 to feed the welding wire into the flux. The welding wire is supplied from the wire reel 6. Each welding power supply device 2a, 2b, 2c, 2d converts the AC power supplied from the commercial power supply P into AC power of a desired frequency and outputs the AC power, and inside the flux, the electrode 8 which is the tip portion of the welding wire. An arc is generated between the object to be welded and the object to be welded W. Welding is performed by the heat of the arc. As a result, welding is performed along the welding line of the object W to be welded. Instead of using the trolley 4, the object W to be welded may be moved or rotated.

The control device 1 performs various controls of the welding system A1. The control device 1 may be a general-purpose computer in which programs for performing various controls of the welding system A1 are installed, or may be a dedicated device for controlling the welding system A1. The control device 1 moves the carriage 4 at a predetermined moving speed. The moving speed is set according to the material and thickness of the work piece W to be welded. The control device 1 instructs the hopper 7 to start and stop the application of the flux. The control device 1 instructs the wire feeding device 5 to start and stop the feeding of the welded wire. It also indicates the feed rate of the weld wire. The feed rate is set according to the set welding current and the like.

The control device 1 instructs the welding power supply devices 2a, 2b, 2c, and 2d to start and stop the power output. Further, the control device 1 transmits a current command value for setting the output current and delay information for delaying the timing of switching between positive and negative of the output AC current. In the present embodiment, since the timing of switching between positive and negative alternating currents to be output is not shifted, the control device 1 transmits "0" as delay information. Further, the control device 1 instructs the welding power supply devices 2a, 2b, 2c, and 2d of the positive / negative switching timing of the output AC current. Specifically, a synchronization signal instructing the positive / negative switching timing is transmitted.

The communication line 31 is a communication line that connects the control device 1 and the welding power supply devices 2a, 2b, 2c, and 2d, and is wired in a bus-type wiring form. The control device 1 and the welding power supply devices 2a, 2b, 2c, and 2d communicate with each other via the communication line 31, for example, by fieldbus communication. The control device 1 can transmit different signals to the welding power supply devices 2a, 2b, 2c, and 2d. On the other hand, since the control device 1 divides the usage time of the communication line 31 and transmits a signal to each welding power supply device 2a, 2b, 2c, 2d, the communication speed on the communication line 31 is the information to be communicated. It becomes slower depending on the amount, and is about 1.2 kbps to 10 Mbps. In this embodiment, it is about 500 kbps. The control device 1 transmits a command signal instructing the start and stop of the power output to the welding power supply devices 2a, 2b, 2c, and 2d via the communication line 31. Further, the control device 1 transmits the current command value and the delay information to the welding power supply devices 2a, 2b, 2c, and 2d via the communication line 31. The communication standard performed by the control device 1 and the welding power supply devices 2a, 2b, 2c, and 2d via the communication line 31 is not limited to fieldbus communication. Further, the wiring form of the communication line 31 is not limited. The communication line 31 corresponds to the "first communication line" of the present invention.

The communication line 32 is a communication line that connects the control device 1 and the welding power supply devices 2a, 2b, 2c, and 2d, and is wired in a bus-type wiring form. The control device 1 and the welding power supply devices 2a, 2b, 2c, and 2d communicate with each other via the communication line 32, for example, according to the HCI (Host Control Interface) communication standard. The HCI communication standard is a communication standard developed for high-speed communication between the control device 1 and the welding power supply devices 2a, 2b, 2c, and 2d. In the HCI communication standard, the amount of communication data heads is reduced to less than half the amount of fieldbus communication heads, and the amount of communication data to be transmitted is reduced. The communication speed on the communication line 32 according to the HCI communication standard is faster than the communication speed on the communication line 31, and is about 25 Mbps to 100 Mbps. In this embodiment, it is about 50 Mbps. The control device 1 transmits a synchronization signal to the welding power supply devices 2a, 2b, 2c, and 2d via the communication line 32. Since the communication line 32 only transmits a synchronization signal and does not transmit or receive other signals, the communication speed is not so slow. The communication standard that the control device 1 and the welding power supply devices 2a, 2b, 2c, and 2d perform via the communication line 32 is not limited to the HCI communication standard, and it is sufficient that the synchronization signal can be transmitted with almost no delay. Further, the wiring form of the communication line 32 is not limited. Further, the communication line 32 may be a dedicated line that transmits a pulse signal for switching between high level and low level as a synchronization signal from the control device 1 to the welding power supply devices 2a, 2b, 2c, and 2d. In this case as well, the communication line 32 can perform high-speed communication from the communication line 31 and transmit the synchronization signal with almost no delay. The communication line 32 corresponds to the "second communication line" of the present invention.

That is, the control device 1 and the welding power supply devices 2a, 2b, 2c, and 2d have two communications, a communication line 32 for high-speed communication of only synchronization signals and a communication line 31 for transmitting other signals. It is connected by a line.

The welding power supply devices 2a, 2b, 2c, and 2d each convert the AC power supplied from the commercial power supply P into AC power having a desired frequency and output the AC power. The welding power supply devices 2a, 2b, 2c, and 2d are connected in parallel to each other. Specifically, one of the output terminals of the welding power supply devices 2a, 2b, 2c, and 2d is connected to each other and is connected to the object W to be welded. The other output terminals of the welding power supply devices 2a, 2b, 2c, 2d are connected to each other and connected to the welding wire. In the following, when the welding power supply device 2a, 2b, 2c, and 2d are not distinguished, it is described as the welding power supply device 2.

As shown in FIG. 1B, the welding power supply device 2 includes a rectifying smoothing circuit 21, an inverter circuit 22, a transformer 23, a rectifying smoothing circuit 24, an inverter circuit 25, a current sensor 26, and a control circuit 27.

The rectifying and smoothing circuit 21 converts the AC power input from the commercial power supply P into DC power and outputs it. The rectifying and smoothing circuit 21 includes a rectifying circuit that rectifies an alternating current and a smoothing capacitor that smoothes the alternating current. The configuration of the rectifying smoothing circuit 21 is not limited.

The inverter circuit 22 is, for example, a single-phase full-bridge type PWM control inverter and includes four switching elements. The inverter circuit 22 converts the DC power input from the rectifying smoothing circuit 21 into high-frequency power and outputs it by switching the switching element with the output control drive signal input from the control circuit 27. The inverter circuit 22 may be of any type as long as it converts DC power into high-frequency power, and may be, for example, a half-bridge type or an inverter circuit having another configuration.

The transformer 23 transforms the high frequency voltage output by the inverter circuit 22 and outputs it to the rectifying smoothing circuit 24. The transformer 23 includes a primary winding 23a and a secondary winding 23b. Each input terminal of the primary winding 23a is connected to each output terminal of the inverter circuit 22. Each output terminal of the secondary winding 23b is connected to each input terminal of the rectifying smoothing circuit 24. The output voltage of the inverter circuit 22 is transformed according to the turns ratio of the primary winding 23a and the secondary winding 23b, and is input to the rectifying smoothing circuit 24. Since the secondary winding 23b is insulated from the primary winding 23a, it is possible to prevent the current input from the commercial power supply P from flowing to the secondary circuit. Further, since the transformer 23 transforms the high frequency voltage output by the inverter circuit 22, it is smaller and lighter than the transformer that transforms the AC voltage of the commercial power supply P.

The rectifying and smoothing circuit 24 converts high-frequency power input from the transformer 23 into DC power and outputs it. The rectifying and smoothing circuit 24 includes a rectifying circuit that rectifies a high-frequency current and a DC reactor that smoothes the high-frequency current. The configuration of the rectifying smoothing circuit 24 is not limited.

The inverter circuit 25 is, for example, a single-phase full-bridge type PWM control inverter and includes four switching elements. The inverter circuit 25 converts the DC power input from the rectifying smoothing circuit 24 into AC power and outputs it by switching the switching element with the switching drive signal input from the control circuit 27. The inverter circuit 25 has a positive electrode property in which the potential of the output terminal 28 (connected to the object W to be welded) is higher than the potential of the output terminal 29 (connected to the welding wire), and the potential of the output terminal 28 is the potential of the output terminal 29. It alternates between the lower polarity and the reverse polarity. The inverter circuit 25 may be of any type as long as it converts DC power into AC power, and may be, for example, a half-bridge type or an inverter circuit having another configuration. The inverter circuit 25 corresponds to the "inverter circuit" of the present invention.

The current sensor 26 detects the output current of the welding power supply device 2, and in this embodiment, it is arranged on a connection line connecting one output terminal and the output terminal 28 of the inverter circuit 25. The current sensor 26 inputs a current value signal corresponding to the detected instantaneous current value to the control circuit 27. The configuration of the current sensor 26 is not limited as long as it detects the output current from the connection line. The location of the current sensor 26 is not limited. For example, the current sensor 26 may be arranged on a connection line connecting the other output terminal and the output terminal 29 of the inverter circuit 25. Further, the current sensor 26 may be arranged between the rectifier circuit 24 and the inverter circuit 25. In this case, the current sensor 26 cannot detect the polarity of the output current, but the control circuit 27 grasps the positive electrode property and the opposite polarity of the inverter circuit 25.

The control circuit 27 is a circuit for controlling the welding power supply device 2, and is realized by, for example, a microcomputer or the like. The control circuit 27 receives a current value signal from the current sensor 26, a command signal, a current command value, and delay information via the communication line 31, and a synchronization signal via the communication line 32. Then, the control circuit 27 outputs a drive signal to the inverter circuit 22 and the inverter circuit 25, respectively.

When the control circuit 27 receives a command signal instructing the start of the power output from the control device 1, the control circuit 27 starts the output of the power by starting the output of the drive signal to the inverter circuit 22 and the inverter circuit 25, respectively. .. Further, when the control circuit 27 receives a command signal instructing to stop the power output from the control device 1, the control circuit 27 stops the output of the drive signal to stop the output of the power.

Further, the control circuit 27 calculates the current effective value from the current value signal input from the current sensor 26. Then, the control circuit 27 generates an output control drive signal for controlling the switching element of the inverter circuit 22 based on the current effective value and the current command value input from the control device 1, and the inverter circuit 27 generates an output control drive signal. Output to 22. That is, the control circuit 27 performs feedback control so that the effective current value matches the current command value.

Further, the control circuit 27 generates a switching drive signal for controlling the switching element of the inverter circuit 25 based on the current value signal input from the current sensor 26 and the internally generated waveform command signal. Output to the inverter circuit 25. That is, the control circuit 27 performs feedback control so that the waveform of the output current matches the waveform commanded by the waveform command signal. In this embodiment, the waveform command signal is a sinusoidal signal. The control circuit 27 may generate a switching drive signal based only on the waveform command signal without using the instantaneous value of the output current.

The control circuit 27 includes a delay unit 271. The delay unit 271 delays the synchronization signal input from the control device 1 according to the delay information input from the control device 1. The synchronization signal delayed by the delay unit 271 is used to generate the waveform command signal. In this embodiment, since "0" is transmitted as the delay information, the delay unit 271 outputs the synchronization signal as it is without delaying it. The control circuit 27 generates a waveform command signal so that the positive / negative is switched at the timing of the synchronous signal delayed by the delay unit 271 (in the present embodiment, the received synchronous signal remains the same).

The control circuit 27 generates a switching drive signal based on the waveform command signal and outputs it to the inverter circuit 25, so that the inverter circuit 25 outputs a sinusoidal alternating current corresponding to the waveform command signal. The alternating current switches between positive and negative at the timing of the synchronization signal.

In the present embodiment, the welding system A1 is a welding system for both AC and DC that can output not only AC power but also DC power. When the welding system A1 outputs DC power, the control device 1 transmits a DC output command signal for outputting DC power to the welding power supply devices 2a, 2b, 2c, and 2d via the communication line 31. .. When the control circuit 27 of the welding power supply devices 2a, 2b, 2c, and 2d receives the DC output command signal, the switching drive signal output to the inverter circuit 25 is fixed to the predetermined switching element in the ON state. It is a signal that fixes other switching elements in the off state. For example, each switching is such that the output terminal and the output terminal 28 on the positive electrode side of the rectifying and smoothing circuit 24 are connected, and the output terminal and the output terminal 29 on the negative electrode side of the rectifying and smoothing circuit 24 remain connected. When the state of the element is fixed, DC power is output with the output terminal 28 as the positive electrode and the output terminal 29 as the negative electrode.

Next, the operation and effect of the welding system A1 according to the present embodiment will be described.

According to this embodiment, the inverter circuit 25 converts the DC power input from the rectifying smoothing circuit 24 into AC power and outputs it. By adjusting the switching drive signal input to the inverter circuit 25, the control circuit 27 can make the alternating current output by the inverter circuit 25 have a desired waveform. The control device 1 transmits a synchronization signal to each of the welding power supply devices 2a, 2b, 2c, and 2d via a relatively high-speed communication line 32. Each welding power supply device 2a, 2b, 2c, 2d can accurately match the timing at which the positive / negative of the output AC current is switched by adjusting the switching drive signal according to the received synchronization signal. ..

FIG. 2 is a waveform diagram showing waveforms of alternating currents output by the welding power supply devices 2a, 2b, 2c, and 2d. FIG. 3A shows the timing at which the control device 1 outputs the synchronization signal X. Since the synchronization signal X is transmitted by high-speed communication via the communication line 32, the input timing of the synchronization signal X in each welding power supply device 2a, 2b, 2c, 2d is also the same. FIG. 3B shows the waveforms of the alternating currents output by the welding power supply devices 2a, 2b, 2c, and 2d. The waveform a shown in FIG. 3B is the waveform of the alternating current output by the welding power supply device 2a, the waveform b is the waveform of the alternating current output by the welding power supply device 2b, and the waveform c is the waveform of the alternating current output by the welding power supply device 2c. It is the waveform of the alternating current to be generated, and the waveform d is the waveform of the alternating current output by the welding power supply device 2d. As shown in FIG. 3B, the positive and negative of each of the waveforms a to d are switched at the timing when the synchronization signal X is output, and the timing of switching between positive and negative is the same. As a result, it is possible to prevent the generation of circulating current due to the timing of switching between the positive and negative of the output alternating current.

Further, according to the present embodiment, each welding power supply device 2a, 2b, 2c, 2d can delay the synchronization signal by the delay unit 271 according to the delay information. Therefore, each of the welding power supply devices 2a, 2b, 2c, and 2d can delay the timing at which the positive / negative of the output AC current is switched according to the synchronization signal delayed by the delay unit 271. That is, each welding power supply device 2a, 2b, 2c, 2d can freely shift the timing at which the positive / negative of the output AC current is switched.

According to this embodiment, the communication speed on the communication line 32 is faster than the communication speed on the communication line 31. Further, the control device 1 transmits a synchronization signal via the communication line 32, and transmits other signals via the communication line 31. Since the communication line 32 transmits only the synchronization signal, the communication speed on the communication line 32 is not so slow. Therefore, the control device 1 can transmit the synchronization signal at a higher speed than other signals. By providing the communication line 32 for transmitting the synchronization signal separately from the communication line 31, the control device 1 can transmit the synchronization signal with almost no delay.

In the present embodiment, the case where the control device 1 transmits "0" as delay information to the welding power supply devices 2a, 2b, 2c, and 2d has been described, but the present invention is not limited to this. The control device 1 may output the same value other than “0” as delay information to the welding power supply devices 2a, 2b, 2c, and 2d. In this case, since each delay unit 271 delays the synchronization signal by the same amount, the timing at which the positive / negative of the alternating current output by each welding power supply device 2a, 2b, 2c, 2d is switched is the same. Further, since the synchronization signal is not delayed in this embodiment, the control circuit 27 of the welding power supply device 2 does not have to include the delay unit 271.

Further, in the present embodiment, the case where the waveform of the output current is a sine wave (see FIG. 2B) has been described, but the present invention is not limited to this. The waveform of the output current may be, for example, a rectangular wave. Further, in the present embodiment, the case where each welding power supply device 2a, 2b, 2c, 2d performs constant current control has been described, but the present invention is not limited to this. Each welding power supply device 2a, 2b, 2c, 2d may perform constant voltage control.

[Second Embodiment]
FIG. 3 is a diagram for explaining the welding system A2 according to the second embodiment, and is a block diagram showing the overall configuration of the welding system A2. In the figure, elements that are the same as or similar to the welding system A1 (see FIG. 1A) according to the first embodiment are designated by the same reference numerals, and redundant description will be omitted. Further, the block diagram showing the internal configuration of the welding power supply device 2 is the same as that of the first embodiment (see FIG. 1B), and thus is omitted.

The welding system A2 includes two carriages 4 and a total of four electrodes 8 arranged two on each carriage 4, and each electrode 8 is supplied with power from a different welding power supply device 2. It is different from the welding system A1 (see FIG. 1) according to the first embodiment.

Although not described in FIG. 3, the welding system A2 is provided with two wire feeding devices 5 and two wire reels 6 on each carriage 4, and like the welding system A1, one on each carriage 4. Each hopper 7 is provided. Of the two bogies 4, the bogie 4 located in front of the traveling direction is referred to as a bogie 41, and the bogie 4 located in the rear is referred to as a bogie 42. Two electrodes 8 are arranged on the carriage 41. Of the two electrodes 8, the electrode 8 located in the front (right side in FIG. 3) in the traveling direction is referred to as the electrode 81, and the electrode 8 located in the rear (left side in FIG. 3) is referred to as the electrode 82. Two electrodes 8 are arranged on the carriage 42. Of the two electrodes 8, the electrode 8 located in the front in the traveling direction is referred to as the electrode 83, and the electrode 8 located in the rear is referred to as the electrode 84. The electrodes 81 to 84 are tips of welded wires fed from different wire reels 6 (not shown) by different wire feeding devices 5 (not shown). The electrodes 81 and 82 are arranged in the flux sprayed from the hopper 7 (not shown) arranged on the carriage 41. The electrodes 83 and 84 are arranged in the flux sprayed from the hopper 7 (not shown) arranged on the carriage 42.

In the welding system A2, while moving the two carriages 41 and 42 along the welding line of the object W to be welded, an arc is generated between the electrodes 81 to 84 and the object W to be welded to perform welding. The tip positions of the electrodes 81 to 84 are aligned in a straight line parallel to the traveling direction. Each of the electrodes 81 to 84 is welded along the welding line. In the present embodiment, the distance between the tip position of the electrode 81 and the tip position of the electrode 82 is the distance L1, the distance between the tip position of the electrode 81 and the tip position of the electrode 83 is the distance L2, and the tip position of the electrode 81. The distance between the electrode 84 and the tip position of the electrode 84 is the distance L3. The arrangement positions and intervals of the electrodes 81 to 84, as well as the tilting direction and angle, and the like are not limited. Further, the tip positions of the electrodes 81 to 84 do not have to be aligned.

One of the output terminals of the welding power supply devices 2a, 2b, 2c, and 2d is connected to each other and is connected to the object to be welded W. The other output terminal of the welding power supply device 2a is connected to the electrode 81, and the welding power supply device 2a supplies electric power to the electrode 81. The other output terminal of the welding power supply device 2b is connected to the electrode 82, and the welding power supply device 2b supplies electric power to the electrode 82. The other output terminal of the welding power supply device 2c is connected to the electrode 83, and the welding power supply device 2c supplies electric power to the electrode 83. The other output terminal of the welding power supply device 2d is connected to the electrode 84, and the welding power supply device 2d supplies electric power to the electrode 84.

In the present embodiment, the delay information output by the control device 1 to each welding power supply device 2a is "0", and the delay information output to each welding power supply device 2b, 2c, 2d depends on the distances L1, L2, and L3. Is set. The delay unit 271 (see FIG. 1B) of each welding power supply device 2a, 2b, 2c, 2d delays the synchronization signal input from the control device 1 according to the delay information input from the control device 1. .. The control circuit 27 (see FIG. 1B) of each welding power supply device 2a, 2b, 2c, 2d generates a waveform command signal so that the positive / negative is switched at the timing of the synchronization signal delayed by the delay unit 271.

Also in this embodiment, the inverter circuit 25 converts the DC power input from the rectifying smoothing circuit 24 into AC power and outputs it. By adjusting the switching drive signal input to the inverter circuit 25, the control circuit 27 can make the alternating current output by the inverter circuit 25 have a desired waveform. The control device 1 transmits a synchronization signal to each of the welding power supply devices 2a, 2b, 2c, and 2d via a relatively high-speed communication line 32. Further, the control device 1 transmits delay information to each of the welding power supply devices 2a, 2b, 2c, and 2d via the communication line 31. Each welding power supply device 2a, 2b, 2c, 2d delays the received synchronization signal by the delay unit 271 according to the received delay information. Then, each welding power supply device 2a, 2b, 2c, 2d delays the timing at which the positive / negative of the output AC current is switched according to the synchronization signal delayed by the delay unit 271.

FIG. 4 is a waveform diagram showing the waveforms of the alternating currents output by the welding power supply devices 2a, 2b, 2c, and 2d. FIG. 3A shows the timing at which the control device 1 outputs the synchronization signal X. Since the synchronization signal X is transmitted by high-speed communication via the communication line 32, the input timing of the synchronization signal X in each welding power supply device 2a, 2b, 2c, 2d is also the same. FIG. 2B shows the timing of the synchronization signal delayed by the delay portion 271 of the welding power supply device 2b. The timing is delayed from the input timing of the synchronization signal X by the phase θ1 corresponding to the distance L1. FIG. 3C shows the timing of the synchronization signal delayed by the delay portion 271 of the welding power supply device 2c. The timing is delayed from the input timing of the synchronization signal X by the phase θ2 corresponding to the distance L2. FIG. 2D shows the timing of the synchronization signal delayed by the delay portion 271 of the welding power supply device 2d. The timing is delayed from the input timing of the synchronization signal X by the phase θ3 corresponding to the distance L3.

FIG. (E) shows the waveforms of the alternating currents output by the welding power supply devices 2a, 2b, 2c, and 2d. The waveform a shown in FIG. 3E is the waveform of the alternating current output by the welding power supply device 2a, the waveform b is the waveform of the alternating current output by the welding power supply device 2b, and the waveform c is the waveform of the alternating current output by the welding power supply device 2c. It is the waveform of the alternating current to be generated, and the waveform d is the waveform of the alternating current output by the welding power supply device 2d. As shown in FIG. 3E, the waveform a is switched between positive and negative at the timing when the synchronization signal X is output. Further, the waveforms b, c, and d are switched between positive and negative at a timing delayed by the phases θ1, θ2, and θ3 from the timing of the synchronization signal X, respectively. As a result, the timing at which the positive / negative of the output alternating current is switched shifts according to the distance between the electrodes 8, so that it is possible to suppress the arcs generated by the adjacent electrodes 8 from attracting each other.

Further, when the delay information has the same value (for example, "0"), the synchronization signal is delayed by the same amount by each delay unit 271, so that each welding power supply device 2a, 2b, 2c, 2d of the AC current to be output. It is also possible to accurately match the timing of switching between positive and negative with others.

In the first and second embodiments, the case where the control device 1 transmits delay information to the welding power supply devices 2a, 2b, 2c, and 2d has been described, but the present invention is not limited to this. When the delay in each welding power supply device 2a, 2b, 2c, 2d is fixed, the control circuit 27 of each welding power supply device 2a, 2b, 2c, 2d has fixed delay information set in advance. May be good.

In the first and second embodiments, the case where the control device 1 transmits various signals to the welding power supply devices 2a, 2b, 2c, and 2d has been described, but the present invention is not limited to this. As shown in the modified example of FIG. 5, any one of the welding power supply devices 2a, 2b, 2c, and 2d (for example, the welding power supply device 2a) becomes a master device having a control function of the control device 1 and is a slave device. Various signals may be transmitted to the welding power supply device (for example, welding power supply device 2b, 2c, 2d). That is, one of the welding power supply devices 2a, 2b, 2c, and 2d may also serve as the control device 1. In this case, it is not necessary to provide the control device 1.

The welding system according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the welding system according to the present invention can be freely redesigned.

A1, A2: Welding system, 1: Control device, 2: Welding power supply device, 25: Inverter circuit, 271: Delay part, 31, 32: Communication line

Claims (5)

It is a welding system for performing submerged arc welding.
A plurality of welding power supply devices, each of which has an inverter circuit and outputs AC power generated by the inverter circuit.
A control device that controls the plurality of welding power supply devices, and
A first communication line for transmitting a command value for commanding each output from the control device to the plurality of welding power supply devices, and
A second communication line that performs high-speed communication from the first communication line and transmits a synchronization signal instructing the timing of switching between positive and negative alternating current from the control device to the plurality of welding power supply devices.
Welding system equipped with. The control device transmits delay information for delaying the timing to each welding power supply device via the first communication line.
Each of the welding power supply devices is
A delay unit for delaying the synchronization signal according to the delay information is provided.
The positive / negative of the output AC current is switched according to the synchronization signal delayed by the delay unit.
The welding system according to claim 1. The output sides of each of the welding power supply devices are connected in parallel to each other.
The delay information transmitted to each of the welding power supplies is the same.
The welding system according to claim 2. The control device transmits a DC output command signal for outputting DC power to each of the welding power supply devices via the first communication line.
When each of the welding power supply devices receives the DC output command signal, the switching of the inverter circuit is stopped and DC power is output.
The welding system according to claim 1. One of the plurality of welding power supply devices also serves as the control device.
The welding system according to any one of claims 1 to 4.

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