Submerged arc welding system

Abstract

To provide a submerged arc welding system which can prevent overturning of a dolly in submerged arc welding using the dolly.SOLUTION: A welding system A1 for performing submerged arc welding includes: a welding power supply device 2 which has an inverter circuit 25 and supplies electric power; a wire feeding device 5 which feeds a welding wire; a welding torch 3 which causes a tip of the welding wire to protrude and performs welding of an object to be weld (welded object) W; a dolly 4 which is equipped with the welding torch 3 and moves along a welding line; and a control device 1 which controls the welding power supply device 2 and the wire feeding device 5. The control device 1 includes: a short circuit detection part 12 which detects a short circuit between the welding wire and the welded object W; and a feeding control unit 13 which stops feeding of the welding wire by the wire feeding device 5 when the short circuit is detected.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a submerged arc welding system for performing submerged arc welding. [Background technology]

[0002] Submerged arc welding has been known for some time. In submerged arc welding, granular flux is spread on the workpiece, a welding wire is fed into the flux, and an arc is generated between the tip of the welding wire and the workpiece to perform welding. In submerged arc welding, welding is performed while moving the welding point by, for example, moving a carriage along the welding line. In submerged arc welding, a thick plate can be welded with high efficiency by passing a large current through a thick welding wire. Patent Document 1 discloses an example of a submerged arc welding device. In the submerged arc welding device, a wire reel wound with a welding wire, a hopper filled with flux, a welding head, and the like are mounted on a traveling carriage. The traveling carriage travels on a rail provided along the welding line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-90410 A Summary of the Invention [Problem to be solved by the invention]

[0004] In submerged arc welding, the welding point is covered with flux. Therefore, even if the welding wire comes into contact with the workpiece and a short circuit occurs, the worker has a hard time noticing the short circuit. If the welding wire continues to be fed without noticing the short circuit, the cart may tip over.

[0005] FIG. 6 is a simplified diagram for explaining the overturning of a carriage due to a short circuit. In the welding system A100 shown in FIG. 6(a), a wire reel 6, a wire feeder 5, and a welding torch 3 are mounted on a carriage 4. This is a simplified diagram seen from the rear of the carriage 4 in the traveling direction. The tip of the welding wire fed by the wire feeder 5 protrudes from the tip of the welding torch 3 as an electrode 8, and an arc is generated between the electrode 8 and the workpiece W to perform welding. The tip of the electrode 8 is covered with flux 79. Note that FIG. 6 illustrates the electrode 8 so that it can be seen through the flux 79. Even if the tip of the welding wire (electrode 8) comes into contact with the workpiece W during welding and a short circuit occurs, it cannot actually be seen from the outside. Therefore, the worker does not notice the short circuit and does not stop welding. Therefore, the wire feeder 5 continues to feed the welding wire, and the tip of the welding wire (electrode 8) pierces the molten pool of the workpiece W. In submerged arc welding, a thick welding wire is generally used. Therefore, if the feeding of the welding wire continues, a moment acts on the carriage 4 in the direction of the arrow Y about the point X, as shown in FIG. 1(b). This causes the carriage 4 to tilt and become unstable, and the carriage may tip over. As the welding progresses, the amount of flux in the hopper mounted on the carriage decreases, and the amount of welding wire on the wire reel mounted on the carriage decreases, so the center of gravity of the carriage changes. If the center of gravity of the carriage shifts to the opposite side of the welding area and a short circuit occurs just before the balance is adjusted, the carriage is more likely to tip over.

[0006] The present invention has been devised in light of the above-mentioned circumstances, and has an object to provide a submerged arc welding system that can prevent a cart from tipping over during submerged arc welding using a cart. [Means for solving the problem]

[0007] The submerged arc welding system provided by the present invention is a submerged arc welding system for performing submerged arc welding, and includes a welding power supply unit having an inverter circuit for supplying power, a wire feeding device for feeding a welding wire, a welding torch for protruding a tip of the welding wire and welding the workpiece, a cart on which the welding torch is mounted and which moves along the welding line, and a control device for controlling the welding power supply unit and the wire feeding device, wherein the control device includes a short circuit detection unit for detecting a short circuit between the welding wire and the workpiece, and a feeding control unit for stopping feeding of the welding wire by the wire feeding device when a short circuit is detected.

[0008] In a preferred embodiment of the present invention, the welding wire further includes a voltage sensor that detects a first voltage between the tip of the welding wire and the workpiece, and the short circuit detection unit detects a short circuit when the first voltage remains equal to or lower than a predetermined voltage for a first period of time.

[0009] In a preferred embodiment of the present invention, the feed control unit causes the wire feeder to stop feeding the welding wire and then feed the welding wire in the opposite direction.

[0010] In a preferred embodiment of the present invention, the welding machine further includes an inclination detection unit that detects an inclination of the carriage, and the feed control unit feeds the welding wire in the opposite direction until the inclination detection unit detects that the carriage has become horizontal.

[0011] In a preferred embodiment of the present invention, the apparatus further includes an abnormality notification unit that notifies an operator of an abnormality, and the abnormality notification unit notifies an abnormality when the short circuit detection unit detects a short circuit. . Effect of the Invention

[0012] According to the present invention, when the short circuit detection unit detects a short circuit between the welding wire and the workpiece, the feed control unit stops the feeding of the welding wire by the wire feeder. Therefore, the submerged arc welding system according to the present invention can prevent the cart from tipping over due to continued feeding of the welding wire. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram for explaining a welding system according to a first embodiment, where (a) is a block diagram showing the overall configuration of the welding system, and (b) is a block diagram showing the internal configuration of a welding power supply and a control device. [Diagram 2] 5 is an example of a flowchart illustrating a tip-over prevention control process performed by the control device. [Diagram 3] 5 is a timing chart for explaining a tip-over prevention control process performed by the control device. [Figure 4] 5A and 5B are diagrams for explaining a welding system according to a second embodiment, where FIG. 5A is a block diagram showing the overall configuration of the welding system, and FIG. 5B is a block diagram showing the internal configurations of a welding power supply and a control device. [Diagram 5] FIG. 13 is a diagram for explaining a welding system according to a third embodiment, and is a block diagram showing the internal configurations of a welding power supply and a control device. [Figure 6] FIG. 11 is a simplified diagram for explaining the tipping over of a carriage due to a short circuit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0015] [First embodiment] Fig. 1 is a diagram for explaining a welding system A1 according to a first embodiment. Fig. 1(a) is a block diagram showing the overall configuration of the welding system A1. Fig. 1(b) is a block diagram showing the internal configuration of a welding power supply 2 and a control device 1.

[0016] The welding system A1 is a welding system for performing submerged arc welding. As shown in FIG. 1(a), the welding system A1 includes a control device 1, a welding power supply device 2, a welding torch 3, a carriage 4, a wire feeder 5, a wire reel 6, a spreader 7, and an electrode 8. The welding system A1 causes the spreader 7 to spread granular flux 79 and the wire feeder 5 to feed the welding wire into the flux 79 while moving the carriage 4 along the welding line of the workpiece W. The welding wire is supplied from the wire reel 6. The welding power supply device 2 converts AC power supplied from a commercial power supply P into power suitable for welding, outputs the power, and generates an arc between the electrode 8, which is the tip of the welding wire, and the workpiece W inside the flux 79. Welding is performed by the heat of the arc. As a result, welding is performed along the welding line of the workpiece W.

[0017] Welding torch 3 guides the welding wire fed by wire feeder 5 to the welding point. The tip of the welding wire becomes electrode 8 protruding from the tip of welding torch 3. Welding torch 3 is provided with a contact tip (not shown) that is disposed at the tip and is electrically connected to welding power supply 2. Welding power supply 2 applies a welding current to the welding wire that is in contact with the contact tip. The welding torch 3 is fixed to the carriage 4 and moves with the movement of the carriage 4. The welding torch 3 may be directly fixed to the carriage 4, or may be indirectly fixed via an arm or the like.

[0018] The control device 1 performs various controls of the welding system A1. The control device 1 may be a general-purpose computer with a program installed therein for performing various controls of the welding system A1, 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 workpiece W. The control device 1 instructs the spraying device 7 to start and stop spraying the flux 79. The spraying device 7 may start and stop spraying the flux 79 manually. The control device 1 instructs the wire feeder 5 to start and stop feeding the welding wire and the feeding speed of the welding wire. The feeding speed is set according to the welding current to be set. The control device 1 instructs the welding power source 2 to output power. The control device 1 also performs control to prevent the carriage 4 from falling over when a short circuit occurs. Details of the control will be described later.

[0019] Welding power supply 2 converts AC power supplied from commercial power source P into AC power of a desired frequency and outputs the AC power. As shown in Fig. 1(b), welding power supply 2 includes a rectifying and smoothing circuit 21, an inverter circuit 22, a transformer 23, a rectifying and smoothing circuit 24, an inverter circuit 25, a current sensor 26, a voltage sensor 27, and a control circuit 28.

[0020] The rectifying and smoothing circuit 21 converts AC power input from the commercial power source P into DC power and outputs it. The inverter circuit 22 converts the DC power input from the rectifying and smoothing circuit 21 into high-frequency power and outputs it by switching the switching elements according to an output control drive signal input from the control circuit 28. The transformer 23 transforms the high-frequency voltage output by the inverter circuit 22 and outputs it to the rectifying and smoothing circuit 24.

[0021] The rectifying and smoothing circuit 24 converts the high frequency power input from the transformer 23 into DC power and outputs it. The inverter circuit 25 converts the DC power input from the rectifying and smoothing circuit 24 into AC power and outputs it by switching the switching elements according to a switching drive signal input from the control circuit 28. The inverter circuit 25 switches between a positive polarity in which the potential of the output terminal a (connected to the workpiece W) is higher than the potential of the output terminal b (connected to the welding wire), and a reverse polarity in which the potential of the output terminal a is lower than the potential of the output terminal b.

[0022] The current sensor 26 detects the output current of the welding power supply 2, and in this embodiment, is disposed on a connection line connecting one output terminal of the inverter circuit 25 and the output terminal a. The output current of the welding power supply 2 detected by the current sensor 26 is approximately equal to the current flowing through the electrode 8. The current sensor 26 outputs a current value signal corresponding to the detected current instantaneous value to the control circuit 28 and the control device 1. The position where the current sensor 26 is disposed is not limited. The voltage sensor 27 detects the output voltage of the welding power supply 2, and in this embodiment, detects the inter-terminal voltage between the output terminal a and the output terminal b. The voltage is approximately equal to the voltage applied between the workpiece W and the tip of the electrode 8. The voltage sensor 27 outputs a voltage value signal corresponding to the detected voltage instantaneous value to the control circuit 28 and the control device 1. The voltage sensor 27 may detect the voltage between the lead wire attached to the welding torch 3 and the lead wire attached to the workpiece W.

[0023] Control circuit 28 is a circuit for controlling welding power supply 2, and is realized by, for example, a microcomputer. Control circuit 28 receives a current value signal from current sensor 26, a voltage value signal from voltage sensor 27, and various command signals and various set values ​​from control device 1. Control circuit 28 then outputs drive signals to inverter circuit 22 and inverter circuit 25. The configuration of welding power supply 2 is not limited.

[0024] Next, the anti-toppling control performed by the control device 1 will be described. The anti-toppling control is a control for preventing the cart 4 from tipping over when a short circuit occurs. Specifically, the control device 1 detects the occurrence of a short circuit during welding, and stops the feeding of the welding wire by the wire feeder 5 when a short circuit is detected. As shown in FIG. 1(b), the control device 1 includes a timing unit 11, a short circuit detection unit 12, and a feed control unit 13 as a configuration for the anti-toppling control.

[0025] The timer unit 11 is a component for measuring time. The timer unit 11 starts and stops measuring time and initializes the measured time in response to instructions from the short circuit detection unit 12 and the feed control unit 13.

[0026] The short circuit detection unit 12 is configured to detect a short circuit between the welding wire and the workpiece W. When a short circuit occurs between the welding wire and the workpiece W, the output terminal a and the output terminal b have the same potential, so that the voltage detected by the voltage sensor 27 becomes "0". The short circuit detection unit 12 calculates an effective voltage value from the voltage value signal input from the voltage sensor 27. Then, when the state in which the effective voltage value is equal to or lower than a predetermined voltage continues for a first time T1, it is determined that a short circuit has occurred. The short circuit detection unit 12 may determine the short circuit using an instantaneous voltage value based on the voltage value signal without calculating the effective voltage value. The predetermined voltage is set to a value that is greater than "0" and close to "0". Even if a short circuit occurs momentarily during welding, if an arc is re-ignited, the welding continues, and the tip of the welding wire does not pierce the workpiece W, so that the cart 4 does not fall over. The first time T1 is set to exclude momentary short circuits, and is set to a time of, for example, about 10 ms. The first time T1 is not limited. When short circuit detection unit 12 detects a short circuit for the first time, it instructs timer unit 11 to start timing, and compares the time measured by timer unit 11 with first time T1. When the short circuit is eliminated before first time T1 has elapsed, or when first time T1 has elapsed, short circuit detection unit 12 stops timing by timer unit 11 and initializes the measured time to "0". When short circuit detection unit 12 detects a short circuit, it outputs a detection signal to feed control unit 13. When short circuit detection unit 12 detects a short circuit, control device 1 stops the output of power by welding power supply 2, the movement of cart 4, and the spraying of flux 79 by sprayer 7. The method of detecting a short circuit by short circuit detection unit 12 is not limited.

[0027] The feed control unit 13 is configured to control the wire feeder 5. The feed control unit 13 instructs the wire feeder 5 to start and stop feeding of the welding wire and the feeding speed of the welding wire. When a detection signal is input from the short circuit detection unit 12, the feed control unit 13 instructs the wire feeder 5 to stop feeding of the welding wire, thereby stopping the feeding of the welding wire. This prevents the cart 4 from tipping over due to continued feeding of the welding wire in a short circuit state.

[0028] However, since the welding wire is fed during the period from when the short circuit actually occurs until the feeding of the welding wire is stopped, the carriage 4 may be slightly tilted. The feed control unit 13 also has a function of correcting this tilt. Specifically, the feed control unit 13 instructs the wire feeder 5 to stop feeding the welding wire, and then instructs the wire feeder 5 to start feeding the welding wire in the opposite direction (so-called retraction). Then, the feed control unit 13 instructs the wire feeder 5 to stop retracting after the second time T2. The second time T2 is set as a time for feeding the welding wire in the opposite direction from the occurrence of the short circuit until the feeding of the welding wire is stopped. The second time T2 is set as an appropriate time based on experiments and simulations. The second time T2 may be a fixed value, or may be changed according to the feeding speed set at the time of the short circuit occurrence. When the feed control unit 13 instructs the wire feeder 5 to stop feeding, the feed control unit 13 instructs the timer unit 11 to start timing, and compares the time counted by the timer unit 11 with the second time T2. When the second time T2 has elapsed, the feed control unit 13 stops the time measurement by the timer unit 11 and initializes the measured time to "0".

[0029] Note that, instead of setting the time for performing the retraction, the feed control unit 13 may retract the length of the welding wire fed from the occurrence of the short circuit to the stop of feeding of the welding wire. Specifically, the feed control unit 13 may reversely rotate the motor (not shown) of the wire feeder 5 by a number of rotations corresponding to the length.

[0030] 2 is an example of a flowchart showing a tip-over prevention control process performed by the control device 1. The tip-over prevention control process is started, for example, when the control device 1 is started.

[0031] First, it is determined whether or not a short circuit has been detected (S1). Specifically, the short circuit detection unit 12 determines whether or not the effective voltage value of the voltage detected by the voltage sensor 27 is equal to or lower than a predetermined voltage. If a short circuit has not been detected (S1: NO), the process returns to step S1, and the determination in step S1 is repeated. On the other hand, if a short circuit has been detected (S1: YES), it is determined whether or not a first time T1 has elapsed (S2). Specifically, the short circuit detection unit 12 determines whether or not the time counted by the timer unit 11 is equal to or greater than the first time T1. The timer unit 11 counts the time from when the short circuit was first detected. If the first time T1 has not elapsed (S2: NO), the process returns to step S1, and the determinations in steps S1 and S2 are repeated.

[0032] In step S2, if the predetermined time has elapsed (S2: YES), the feeding of the welding wire is stopped (S3). Specifically, the feeding control unit 13 instructs the wire feeder 5 to stop feeding the welding wire. This causes the wire feeder 5 to stop feeding the welding wire. Next, retraction of the welding wire is started (S4). Specifically, the feeding control unit 13 instructs the wire feeder 5 to start feeding the welding wire in the opposite direction. This causes the wire feeder 5 to start retracting the welding wire. Next, it is determined whether or not a second time T2 has elapsed (S5). Specifically, the feeding control unit 13 determines whether or not the time counted by the timing unit 11 is equal to or greater than the second time T2. The timing unit 11 counts the time from when the retraction started. If the second time T2 has not elapsed (S5: NO), the process returns to step S5, and the determination of step S5 is repeated. That is, the feed control unit 13 waits until the time measured by the timer unit 11 reaches the second time T2. If the second time T2 has elapsed (S5: YES), the retraction is stopped (S6), and the overturn prevention control process is ended.

[0033] It should be noted that the process shown in the flowchart of FIG. 2 is merely an example, and the overturn prevention control process performed by the control device 1 is not limited to the above.

[0034] FIG. 3 is a timing chart for explaining the overturn prevention control process performed by the control device 1. FIG. 3(a) shows the time change of the effective voltage value of the detected voltage detected by the voltage sensor 27. FIG. 3(b) shows the time change of the time measured by the timer 11. FIG. 3(c) shows the time change of the feed speed of the welding wire. When the welding wire is fed in the forward direction, the feed speed is a positive value, and when the welding wire is fed in the reverse direction, the feed speed is a negative value. Note that the vertical and horizontal axes of the timing chart shown in FIG. 3 are appropriately enlarged or reduced for ease of understanding, and each waveform shown is simplified, exaggerated, or emphasized for ease of understanding.

[0035] Up until time t1, the welding voltage is detected by voltage sensor 27. At time t1, the detected voltage becomes "0" (below a predetermined voltage). This causes timing in timing unit 11 to begin, and the measured time increases according to the elapsed time. However, at time t2, before the elapsed time reaches T1, the welding voltage is detected as the detected voltage, which is greater than the predetermined voltage. Therefore, short circuit detection unit 12 does not detect the occurrence of a short circuit. Because the short circuit was eliminated before the first time T1 elapsed, at time t2, timing unit 11 stops timing and initializes the measured time to "0".

[0036] At time t3, the detected voltage becomes "0" (less than the predetermined voltage) again. This causes timing in the timer 11 to start, and the measured time increases according to the elapsed time. Then, at time t4, the elapsed time reaches the first time T1, so the short circuit detection unit 12 detects the occurrence of a short circuit, and the feed control unit 13 instructs the wire feeder 5 to stop feeding the welding wire. This causes the welding wire feed speed to decrease, and becomes "0" at time t5. After the instruction to stop feeding is given, the feed speed decreases at an inclination due to inertia. Since the first time T1 has elapsed, at time t4, the timer 11 stops timing and initializes the measured time to "0".

[0037] At time t4, the feed control unit 13 instructs the wire feeder 5 to stop feeding the welding wire, and then instructs the wire feeder 5 to start feeding (retracting) the welding wire in the opposite direction. As a result, from time t5, the wire feeder 5 starts retracting the welding wire, and the feeding speed of the welding wire decreases (the speed in the opposite direction increases) and becomes a predetermined retraction speed. Note that the feeding speed decreases with a slope due to inertia after the instruction to start retraction. At time t4, the timing unit 11 starts timing, and the timing time increases according to the elapsed time. Then, at time t6, the elapsed time becomes the second time T2, and the feed control unit 13 instructs the wire feeder 5 to stop retraction. After the instruction to stop retraction, the feeding speed increases with a slope due to inertia (the speed in the opposite direction decreases) and becomes "0" at time t7. Since the second time T2 has elapsed, at time t6, the timing unit 11 stops timing and initializes the measured time to "0."

[0038] The integral value of the feed speed from time t3 to time t5 (the area of ​​the hatched region S1) corresponds to the length of the welding wire fed from the occurrence of a short circuit to the stop of feeding of the welding wire. Also, the integral value of the feed speed from time t5 to time t7 (the area of ​​the hatched region S2) corresponds to the length of the welding wire fed in the opposite direction by retraction. The second time T2 is set so that the area of ​​region S2 is equal to the area of ​​region S1.

[0039] Next, the operation and effects of the welding system A1 according to this embodiment will be described.

[0040] According to this embodiment, when short circuit detection unit 12 detects a short circuit between the welding wire and workpiece W, it outputs a detection signal to feed control unit 13. When a detection signal is input from short circuit detection unit 12, feed control unit 13 instructs wire feeder 5 to stop feeding of the welding wire. This causes wire feeder 5 to stop feeding of the welding wire. Therefore, welding system A1 can prevent cart 4 from tipping over due to continued feeding of the welding wire during a short circuit. The present invention is particularly effective when setting conditions before actual welding work (welding in which each parameter is changed and trial welding is performed to determine welding conditions).

[0041] According to the present embodiment, the short circuit detection unit 12 determines that a short circuit has occurred when the effective voltage value remains equal to or lower than a predetermined voltage for a first time T1. Therefore, the welding system A1 can prevent the welding wire feed from being stopped due to a momentary short circuit.

[0042] According to the present embodiment, the feed control unit 13 receives a detection signal from the short circuit detection unit 12, instructs the wire feeder 5 to stop feeding the welding wire, and then instructs the wire feeder 5 to start feeding the welding wire in the opposite direction (so-called retraction). The wire feeder 5 retracts the welding wire. This allows the welding system A1 to correct the inclination of the carriage 4 caused by the feeding of the welding wire during the period from when the short circuit actually occurs until the feeding of the welding wire stops. The feed control unit 13 instructs the carriage 4 to stop retracting after a second time T2 has elapsed since the instruction to start retracting. This allows the welding system A1 to feed the welding wire in the opposite direction for the period from when the short circuit occurs until the feeding of the welding wire stops, and therefore the inclination of the carriage 4 can be returned to the original state (horizontal state).

[0043] In this embodiment, the case where the feed control unit 13 issues a command to stop feeding and then issues a command to retract has been described, but this is not limited to this. When a short circuit is detected, the feed control unit 13 may only issue a command to stop feeding, and may not need to issue a command to retract.

[0044] Second Embodiment FIG. 4 is a diagram for explaining a welding system A2 according to a second embodiment. FIG. 4(a) is a block diagram showing the overall configuration of the welding system A2. FIG. 4(b) is a block diagram showing the internal configuration of a welding power supply 2 and a control device 1. In FIG. 4, elements that are the same as or similar to those in the first embodiment are given the same reference numerals as those in the first embodiment. The welding system A2 according to this embodiment differs from the welding system A1 according to the first embodiment in that it includes an inclination detection unit that detects the inclination of the carriage 4.

[0045] In this embodiment, the carriage 4 includes an inclination sensor 41. The inclination sensor 41 is, for example, a three-axis acceleration sensor that detects acceleration in each axial direction and outputs the detection value to the feed control unit 13. The feed control unit 13 calculates the inclination of the carriage 4 based on the detection value input from the inclination sensor 41. When retracting the welding wire, the feed control unit 13 continues retraction based on the calculated inclination of the carriage 4 until it detects that the carriage 4 has become horizontal. Note that the configuration of the inclination sensor 41 is not limited as long as it can detect the inclination of the carriage 4. For example, the inclination sensor 41 may be a gyro sensor. Furthermore, the welding system A2 may include a mechanism that can detect the inclination of the carriage 4 from outside the carriage 4 instead of the carriage 4 including the inclination sensor 41. For example, the carriage 4 and the workpiece W may be imaged by a camera, and the inclination of the carriage 4 relative to the workpiece W may be calculated by image processing.

[0046] In this embodiment, when the short circuit detection unit 12 detects a short circuit, the feed control unit 13 stops the feeding of the welding wire. Therefore, the welding system A2 can prevent the cart 4 from falling over due to the continuation of the feeding of the welding wire during a short circuit. Furthermore, the short circuit detection unit 12 determines that a short circuit has occurred when the state in which the voltage effective value is equal to or lower than a predetermined voltage continues for a first time T1. Therefore, the welding system A2 can prevent the feeding of the welding wire from being stopped due to an instantaneous short circuit. Furthermore, the feed control unit 13 causes the cart 4 to retract after stopping the feeding of the welding wire. This allows the welding system A2 to correct the inclination of the cart 4 caused by the feeding of the welding wire during the period from when the short circuit actually occurs until the feeding of the welding wire is stopped. Furthermore, according to this embodiment, when performing retraction, the feed control unit 13 continues the retraction until it detects that the cart 4 has become horizontal. This allows the welding system A2 to return the inclination of the cart 4 to the original state (horizontal state).

[0047] Third Embodiment Fig. 5 is a diagram for explaining a welding system A3 according to a third embodiment. Fig. 5 is a block diagram showing the internal configuration of a welding power supply 2 and a control device 1 of the welding system A3. In Fig. 5, elements that are the same as or similar to those in the first embodiment are given the same reference numerals as those in the first embodiment. The welding system A3 according to this embodiment differs from the welding system A1 according to the first embodiment in that it includes an abnormality notification unit that notifies an abnormality when a short circuit is detected.

[0048] The control device 1 according to the present embodiment includes an abnormality notification unit 14. The abnormality notification unit 14 is configured to notify an operator of an abnormality. When the short circuit detection unit 12 according to the present embodiment detects a short circuit, it also outputs a detection signal to the abnormality notification unit 14. When the detection signal is input from the short circuit detection unit 12, the abnormality notification unit 14 notifies an operator of an abnormality. The method of notifying an abnormality by the abnormality notification unit 14 is not limited. For example, the abnormality notification unit 14 may notify an abnormality by voice using a speaker or a buzzer, or may notify an abnormality by light using a light. In addition, the abnormality notification unit 14 may display an image or text notifying an abnormality on a display screen (not shown).

[0049] In this embodiment, when the short circuit detection unit 12 detects a short circuit, the feed control unit 13 stops the feeding of the welding wire. Therefore, the welding system A3 can prevent the cart 4 from falling over due to the continuation of the feeding of the welding wire during a short circuit. Furthermore, the short circuit detection unit 12 determines that a short circuit has occurred when the state in which the voltage effective value is equal to or lower than a predetermined voltage continues for a first time T1. Therefore, the welding system A3 can prevent the feeding of the welding wire from being stopped due to an instantaneous short circuit. Furthermore, the feed control unit 13 causes the cart 4 to retract after stopping the feeding of the welding wire. This allows the welding system A3 to correct the inclination of the cart 4 caused by the feeding of the welding wire during the period from when the short circuit actually occurs until the feeding of the welding wire is stopped. Furthermore, the feed control unit 13 instructs the cart 4 to stop the retract after a second time T2 has elapsed since the instruction to start the retract. As a result, welding system A3 can feed the amount of welding wire fed from the occurrence of a short circuit to the stop of feeding of the welding wire in the opposite direction, so that the inclination of cart 4 can be returned to the original state (horizontal state). Furthermore, according to this embodiment, when short circuit detection unit 12 detects a short circuit, abnormality notification unit 14 notifies the worker of the abnormality. In submerged arc welding, the welding point is covered with flux 79, so the occurrence of a short circuit cannot be visually confirmed from the outside. In welding system A3, when a short circuit occurs, abnormality notification unit 14 notifies the worker of the abnormality, so that the occurrence of a short circuit can be made aware of the occurrence of the short circuit.

[0050] The welding system according to the present invention is not limited to the above-described embodiment, and the specific configuration of each part of the welding system according to the present invention can be freely designed in various ways. [Explanation of symbols]

[0051] A1: welding system, 1: control device, 12: short circuit detection unit, 13: feed control unit, 14: abnormality notification unit, 2: welding power supply unit, 22: inverter circuit, 27: voltage sensor, 3: welding torch, 4: cart, 41: tilt detection unit, 5: wire feeder

Claims

1. 1. A submerged arc welding system for performing submerged arc welding, comprising: a welding power supply device having an inverter circuit for supplying power; a wire feeder that feeds a welding wire; a welding torch for welding an object to be welded by projecting a tip of the welding wire; A carriage on which the welding torch is mounted and which moves along the weld line; a control device for controlling the welding power supply and the wire feeder; Equipped with The control device includes: a short circuit detection unit that detects a short circuit between the welding wire and the workpiece; a feed control unit that stops feeding of the welding wire by the wire feeder when a short circuit is detected; Equipped with Submerged arc welding system.

2. a voltage sensor that detects a first voltage between the tip of the welding wire and the workpiece; the short circuit detection unit detects a short circuit when a state in which the first voltage is equal to or lower than a predetermined voltage continues for a first period of time.

2. The submerged arc welding system of claim 1.

3. The feed control unit causes the wire feeder to stop feeding the welding wire and then feeds the welding wire in the opposite direction.

3. A submerged arc welding system according to claim 1 or 2.

4. Further comprising a tilt detection unit that detects the tilt of the cart, The feed control unit feeds the welding wire in the opposite direction until the tilt detection unit detects that the carriage is in a horizontal state.

4. The submerged arc welding system of claim 3.

5. Further comprising an abnormality notification unit that notifies an operator of an abnormality, The abnormality notification unit notifies an abnormality when the short circuit detection unit detects a short circuit.

2. The submerged arc welding system of claim 1.

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