Submerged arc welding system

Abstract

To provide a submerged arc welding system that can suppress a length of a voltage detection wire for detecting an arc voltage, in submerged arc welding using a carrier.SOLUTION: A welding system A1, which performs submerged arc welding, comprises: a welding torch 3 that supports an electrode 8 that generates arc between an object W to be welded and the torch; a welding power supply device 2 that supplies electric power to the welding torch 3; a control device 1 that controls the welding power supply device 2; and a carrier 4 loaded with the welding torch 3 and the control device 1, which moves along a welding wire. The control device 1 comprises a voltage detecting part 11 that detects a voltage between the electrode 8 and the object W to be welded and converts the voltage to a voltage value that is a digital signal to output the value, and a communicating part 13 that performs digital communication with the welding power supply device 2. The communicating part 13 transmits a voltage value inputted from the voltage detecting part 11, to the welding power supply device 2.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 dispersed 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, for example, by moving a cart along the welding line. In submerged arc welding, thick plates can be welded with high efficiency by passing a large current through a thick welding wire.

[0003] Generally, when performing constant voltage control, feedback control is desirable because feedforward control reduces welding performance. Patent Document 1 discloses an example of a submerged arc welding welding power supply that performs feedback control. The control circuit of this welding power supply performs feedback control by generating an output control drive signal based on a detection signal and a command value input from a current sensor or voltage sensor and outputting the signal to an inverter circuit. When performing constant voltage control of the arc voltage, in order to improve the accuracy of arc voltage detection, it is necessary to detect the voltage as close to the arc as possible. Therefore, it is desirable to connect the tip of the voltage detection wire to the contact tip of the welding torch. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-45136 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when connecting the tip of the voltage detection wire to the contact tip of the welding torch, the voltage detection wire needs to be long enough to connect the welding power supply and the contact tip, which moves with the cart. Since the welding power supply and the cart can be more than 50 m apart, the voltage detection wire can become very long. The longer the voltage detection wire, the more likely it is that surrounding noise will be superimposed. Furthermore, long voltage detection wires are more difficult to route.

[0006] The present invention was devised in light of the above-mentioned circumstances, and aims to provide a submerged arc welding system that can reduce the length of a voltage detection line for detecting arc voltage in submerged arc welding using a carriage. [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 torch that supports an electrode that generates an arc between the electrode and the workpiece, a welding power supply that supplies power to the welding torch, a control device that controls the welding power supply, and a carriage that carries the welding torch and the control device and moves along the weld line, the control device including a voltage detection unit that detects the voltage between the electrode and the workpiece, converts it into a voltage value that is a digital signal, and outputs it, and a communication unit that performs digital communication with the welding power supply, and the communication unit transmits the voltage value input from the voltage detection unit to the welding power supply.

[0008] In a preferred embodiment of the present invention, the welding torch further includes a wire feeding device that feeds a welding wire and causes a tip portion of the welding wire to protrude from a tip of the welding torch as the electrode, the welding torch includes a contact tip that contacts the welding wire to pass current, and the voltage detection unit includes a first voltage detection wire and a second voltage detection wire, the first voltage detection wire is conductively connected to the contact tip, and the second voltage detection wire is conductively connected to the workpiece.

[0009] In a preferred embodiment of the present invention, the carriage includes a tire electrically connected to the workpiece, and the second voltage detection line is electrically connected to the carriage.

[0010] In a preferred embodiment of the present invention, the communication unit and the welding power supply are connected by a communication line and communicate with each other via CAN communication.

[0011] In a preferred embodiment of the present invention, the communication unit and the welding power supply communicate with each other via wireless communication. [Effects of the Invention]

[0012] According to the present invention, the welding torch and the control device are mounted on a carriage. Therefore, the electrode supported by the welding torch is close to the voltage detection unit provided in the control device. Therefore, the submerged arc welding system according to the present invention can reduce the length of the voltage detection line for detecting the voltage of the electrode. By reducing the length of the voltage detection line, which is prone to noise superposition, noise superposition on the voltage detection line is reduced. Furthermore, according to the present invention, the communication unit transmits the voltage value detected by the voltage detection unit to the welding power supply via digital communication. Therefore, in the submerged arc welding system according to the present invention, the welding power supply can acquire the voltage value of the arc voltage with reduced influence of noise compared to when using a voltage detection signal that is an analog signal input from the voltage detection line. [Brief explanation of the drawings]

[0013] [Figure 1] 1A and 1B are diagrams for explaining a welding system according to a first embodiment, in which FIG. 1A is a block diagram showing the overall configuration of the welding system, and FIG. 1B is a block diagram showing the internal configuration of a welding power supply, a control device, and a welding torch. [Figure 2] FIG. 10 is a diagram for explaining a welding system according to a second embodiment, and is a block diagram showing the internal configurations of a welding power supply, a control device, a welding torch, and a carriage. [Figure 3]FIG. 10 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, a control device, and a welding torch. DETAILED DESCRIPTION OF THE INVENTION

[0014] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0015] [First embodiment] 1A and 1B are diagrams illustrating a welding system A1 according to a first embodiment. Fig. 1A is a block diagram showing the overall configuration of the welding system A1. Fig. 1B is a block diagram showing the internal configuration of a welding power supply, a control device, and a welding torch.

[0016] Welding system A1 is a welding system for performing submerged arc welding. As shown in FIG. 1(a), welding system A1 includes control device 1, welding power supply 2, welding torch 3, carriage 4, wire feeder 5, wire reel 6, sprayer 7, and electrode 8. Welding system A1 moves carriage 4 along a weld line on workpieces W, causing sprayer 7 to spray granular flux 79 and wire feeder 5 to feed welding wire into flux 79. The welding wire is supplied from wire reel 6. Welding power supply 2 converts AC power supplied from commercial power source P into power suitable for welding and outputs it. An arc is generated within flux 79 between electrode 8, which is the tip of the welding wire, and workpieces W. The heat of the arc causes welding. This results in welding along the weld line on workpieces 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, which protrudes from the tip of welding torch 3. Therefore, electrode 8 is supported by welding torch 3. Welding torch 3 has contact tip 31 located at the tip and connected to welding power supply 2. Welding power supply 2 applies a welding current to the welding wire that contacts contact tip 31. Welding torch 3 is mounted on carriage 4 and moves as carriage 4 moves. Note that welding torch 3 may be fixed directly to carriage 4 or indirectly via an arm or the like.

[0018] The control device 1 performs various controls of the welding system A1. The control device 1 is equipped with a control board equipped with a microcomputer, a communication module, etc., an operation panel for operation, a display panel for display, etc. The control device 1 is mounted on the carriage 4 and moves along with the movement of the carriage 4. The control device 1 moves the carriage 4 at a predetermined speed. The speed is set depending on the material and thickness of the workpiece W. The control device 1 instructs the sprayer 7 to start and stop spraying the flux 79. Note that the sprayer 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 to set the welding wire feed speed. The feed speed is set depending on the welding current to be set, etc.

[0019] Control device 1 also communicates with welding power supply 2 and controls welding power supply 2. Control device 1 commands welding power supply 2 to start and stop outputting welding power. Control device 1 also detects arc voltage and transmits the detected voltage value to welding power supply 2. As shown in FIG. 1(b), control device 1 includes voltage detection unit 11 and communication unit 13. Note that control device 1 also includes other components, but these are not shown in FIG. 1 and will not be described in detail.

[0020] Voltage detection unit 11 detects the arc voltage, which is the voltage between the tip of electrode 8 and the workpiece W. Voltage detection unit 11 is equipped with voltage detection wires 111 and 112. The tip of voltage detection wire 111 is conductively connected to contact tip 31 of welding torch 3. Control device 1 and welding torch 3 are both mounted on carriage 4. Voltage detection wire 111 may be of any length that allows connection between voltage detection unit 11 and contact tip 31 on carriage 4, and it is desirable that the length be as short as possible. The tip of voltage detection wire 112 is conductively connected to workpiece W. Voltage detection wire 112 may be of any length that allows connection between the connection position to workpiece W and voltage detection unit 11 (carriage 4) to be maintained within the movement range of carriage 4 during one welding operation. If welding exceeds the reach of voltage detection wire 112, the connection position of voltage detection wire 112 to workpiece W must be changed.

[0021] The voltage detection unit 11 detects a voltage detection signal (analog signal) corresponding to the voltage between the voltage detection line 111 and the voltage detection line 112, converts the voltage detection signal (analog signal) into a digital signal, and detects the arc voltage value. The arc voltage value is the instantaneous value of the arc voltage. The arc voltage value may be the absolute value of the instantaneous value of the arc voltage, or may be the effective value or the average value of the absolute value. The voltage detection unit 11 outputs the detected arc voltage value to the communication unit 13. The arc voltage value is also used for processing inside the control device 1.

[0022] Communication unit 13 communicates with welding power supply 2 (communication unit 27, described later) via communication line 9. Communication unit 13 and communication unit 27 communicate digitally, and in this embodiment, they communicate in accordance with the CAN (Controller Area Network) communication standard. The standard of communication between communication unit 13 and communication unit 27 is not limited, and may be, for example, field bus communication or Ethernet communication. Communication unit 13 transmits a welding power output start command and an output stop command to welding power supply 2 (communication unit 27). Communication unit 13 also transmits the arc voltage value input from voltage detection unit 11 to welding power supply 2 (communication unit 27). The information transmitted by communication unit 13 to welding power supply 2 (communication unit 27) is not limited to this. Communication unit 13 receives information such as the current value of the output current of welding power supply 2 from welding power supply 2 (communication unit 27). The information received by communication unit 13 from welding power supply 2 (communication unit 27) is not limited.

[0023] Welding power supply 2 converts AC power supplied from commercial power supply P into AC power of a desired frequency and supplies it to welding torch 3. As shown in FIG. 1(b), welding power supply 2 includes rectifying and smoothing circuit 21, inverter circuit 22, transformer 23, rectifying and smoothing circuit 24, inverter circuit 25, current sensor 26, communication unit 27, and control circuit 28.

[0024] 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 in response 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. The rectifying and smoothing circuit 24 converts the high-frequency power input from the transformer 23 into DC power and outputs it.

[0025] Inverter circuit 25 converts the DC power input from rectifying and smoothing circuit 24 into AC power and outputs it by switching the switching element in response to a switching drive signal input from control circuit 28. Inverter circuit 25 switches between a positive polarity in which the potential of output terminal a (connected to workpiece W) is higher than the potential of output terminal b (connected to contact tip 31 of welding torch 3), and a reverse polarity in which the potential of output terminal a is lower than the potential of output terminal b.

[0026] Current sensor 26 detects the output current of welding power supply 2, and in this embodiment is disposed on a connection line connecting one output terminal of inverter circuit 25 with output terminal a. The output current of welding power supply 2 detected by current sensor 26 is substantially equal to the current flowing through electrode 8. There are no limitations on the location where current sensor 26 is disposed. Current sensor 26 detects a current detection signal (analog signal) corresponding to the output current of welding power supply 2, and outputs the signal to control circuit 28.

[0027] The communication unit 27 communicates with the communication unit 13 of the control device 1 via the communication line 9. The communication unit 27 receives a power output start command and an output stop command from the control device 1 (communication unit 13) and inputs them to the control circuit 28. The communication unit 27 also receives an arc voltage value from the control device 1 (communication unit 13) and inputs them to the control circuit 28. Note that the information that the communication unit 27 receives from the control device 1 (communication unit 13) is not limited to this. Also, as will be described later, the communication unit 27 transmits the output current value input from the control circuit 28 to the control device 1 (communication unit 13). Note that the information that the communication unit 27 transmits to the control device 1 (communication unit 13) is not limited.

[0028] Control circuit 28 is a circuit for controlling welding power supply 2, and is realized by, for example, a microcomputer. Control circuit 28 controls the driving and stopping of inverter circuits 22, 25 based on an output start command and an output stop command received from control device 1 (communication unit 13) via communication unit 27. Specifically, control circuit 28 starts outputting a driving signal to inverter circuits 22, 25 when it receives an output start command, and stops outputting the driving signal when it receives an output stop command.

[0029] Control circuit 28 also detects the output current value, which is a digital signal, based on the current detection signal input from current sensor 26. The output current value is the instantaneous value of the output current obtained by converting the current detection signal (analog signal) into a digital signal. The output current value may be the absolute value of the instantaneous value of the output current, or the average value of the effective value or absolute value. Control circuit 28 receives the arc voltage value from control device 1 (communication unit 13) via communication unit 27. Control circuit 28 generates an output control drive signal to be output to inverter circuit 22 and a switching drive signal to be output to inverter circuit 25, depending on the detected output current value, the arc voltage value received from control device 1, various setting values, and the like. Control circuit 28 can also detect the occurrence of a short circuit between electrode 8 and workpiece W during welding, based on the arc voltage value received from control device 1. Control circuit 28 also transmits the detected output current value to control device 1 via communication unit 27. The configuration of welding power supply 2 is not limited.

[0030] Next, the operation and effects of the welding system A1 according to this embodiment will be described.

[0031] According to this embodiment, welding torch 3 and control device 1 are mounted on carriage 4. Therefore, electrode 8 protruding from the tip of welding torch 3 and voltage detection unit 11 of control device 1 are closely spaced apart. Therefore, welding system A1 can reduce the length of voltage detection wire 111 for detecting the voltage of electrode 8. By reducing the length of voltage detection wire 111, which is prone to noise superposition, noise superposition on voltage detection wire 111 is reduced. Furthermore, according to this embodiment, communication unit 13 transmits the arc voltage value detected by voltage detection unit 11 to welding power supply 2 (communication unit 27) via communication line 9 by digital communication. Therefore, welding power supply 2 can acquire the arc voltage value with reduced noise influence compared to when a voltage detection signal, which is an analog signal input from the voltage detection wire, is used. Furthermore, reducing the length of voltage detection wire 111 simplifies routing of voltage detection wire 111, reducing the risk of failure due to wire breakage. Furthermore, the cost of voltage detection wire 111 can be reduced.

[0032] Furthermore, according to this embodiment, voltage detection unit 11 includes voltage detection wire 111 conductively connected to contact tip 31 of welding torch 3, and voltage detection wire 112 conductively connected to workpiece W. Therefore, voltage detection unit 11 can accurately detect the arc voltage.

[0033] Furthermore, in this embodiment, communication units 13 and 27 communicate with each other via communication line 9 in accordance with the CAN communication standard. This allows communication units 13 and 27 to communicate digitally, so that welding power supply 2 can receive the arc voltage value from control device 1 as a digital signal.

[0034] In this embodiment, the case where welding power supply 2 is capable of outputting AC power has been described, but this is not limiting. Welding power supply 2 may be a DC-only power supply that does not include inverter circuit 25.

[0035] In addition, in this embodiment, the case where welding power supply 2 controls output using inverter circuit 22 has been described, but this is not limiting. Welding power supply 2 may also control output using a configuration other than an inverter circuit, such as a thyristor-controlled power supply.

[0036] In the present embodiment, welding system A1 has been described as a case in which wire feeder 5 feeds a welding wire and the tip portion of the welding wire protruding from the tip of welding torch 3 serves as electrode 8, but this is not limited to this. Welding system A1 may use an electrode made of non-melting material such as tungsten as electrode 8.

[0037] Second Embodiment 2 is a diagram for explaining a welding system A2 according to a second embodiment, and is a block diagram showing the internal configuration of a welding power supply 2, a control device 1, a welding torch 3, and a carriage 4. In FIG. 2, 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. In welding system A2 according to this embodiment, the connection destination of the tip of voltage detection wire 112 differs from that of welding system A1 according to the first embodiment.

[0038] In this embodiment, the tip of voltage detection wire 112 is conductively connected to a metal portion of body 41 of bogie 4. The metal portion of body 41 is conductively connected to tires 42 via an axle or the like. Bogie 4 runs on objects to be welded W. Tires 42 are in contact with objects to be welded W and are conductive. Therefore, voltage detection wire 112 is conductively connected to objects to be welded W via body 41 and tires 42 of bogie 4.

[0039] In this embodiment as well, welding torch 3 and control device 1 are mounted on carriage 4, so welding system A2 can reduce the length of voltage detection wire 111 for detecting the voltage of electrode 8. Therefore, noise is prevented from being superimposed on voltage detection wire 111. Furthermore, communication unit 13 transmits the arc voltage value detected by voltage detection unit 11 to welding power supply 2 (communication unit 27) via communication line 9 by digital communication. Therefore, welding power supply 2 can acquire the arc voltage value while reducing the influence of noise. Furthermore, reducing the length of voltage detection wire 111 simplifies the routing of voltage detection wire 111 and reduces the cost of voltage detection wire 111.

[0040] Furthermore, welding system A2 according to this embodiment has a configuration in common with welding system A1, thereby achieving the same effects as welding system A1. Furthermore, according to this embodiment, voltage detection wire 112 is conductively connected to a metal portion of body 41 of carriage 4. Therefore, welding system A2 can also reduce the length of voltage detection wire 112. Furthermore, welding system A2 does not need to change the connection position of voltage detection wire 112 even when welding over a wide area. Note that if carriage 4 does not travel on workpiece W but travels on rails installed along the weld line, it is sufficient to conductively connect the rails to workpiece W.

[0041] Third Embodiment 3 is a diagram for explaining a welding system A3 according to a third embodiment, and is a block diagram showing the internal configurations of a welding power supply 2, a control device 1, and a welding torch 3. In FIG. 3, elements that are the same as or similar to those in the first embodiment are given the same reference numerals. Welding system A3 according to this embodiment differs from welding system A1 according to the first embodiment in that communication unit 13 and communication unit 27 communicate wirelessly.

[0042] In welding system A3 according to this embodiment, communication unit 13 of control device 1 and communication unit 27 of welding power supply 2 perform wireless digital communication. Note that the communication standard for wireless communication is not limited.

[0043] In this embodiment as well, welding torch 3 and control device 1 are mounted on carriage 4, so welding system A3 can reduce the length of voltage detection wire 111 for detecting the voltage of electrode 8. Therefore, noise is prevented from being superimposed on voltage detection wire 111. Furthermore, according to this embodiment, communication unit 13 transmits the arc voltage value detected by voltage detection unit 11 to welding power supply 2 (communication unit 27) via digital wireless communication. Therefore, welding power supply 2 can acquire the arc voltage value while reducing the influence of noise. Furthermore, reducing the length of voltage detection wire 111 simplifies the routing of voltage detection wire 111 and reduces the cost of voltage detection wire 111.

[0044] Furthermore, welding system A3 according to this embodiment has a configuration common to welding system A1, and thus achieves the same effects as welding system A1. Furthermore, according to this embodiment, communication unit 13 and communication unit 27 communicate wirelessly. Therefore, welding system A3 does not require a communication line connecting communication unit 13 and communication unit 27. As a result, welding system A3 does not need to lay a communication line, and the cost for the communication line can be reduced.

[0045] The submerged arc welding system according to the present invention is not limited to the above-described embodiment, and the specific configuration of each part of the submerged arc welding system according to the present invention can be freely designed and modified in various ways. [Explanation of symbols]

[0046] A1 to A3: welding system, 1: control device, 11: voltage detection unit, 111, 112: voltage detection line, 12: communication unit, 2: welding power supply unit, 3: welding torch, 31: contact tip, 4: dolly, 42: tire, 5: wire feeder, 9: communication line, W: workpiece

Claims

1. 1. A submerged arc welding system for performing submerged arc welding, comprising: a welding torch supporting an electrode that generates an arc between the electrode and the workpiece; a welding power supply that supplies power to the welding torch; a control device for controlling the welding power supply; a carriage on which the welding torch and the control device are mounted and which moves along the weld line; Equipped with The control device a voltage detection unit that detects a voltage between the electrode and the workpiece, converts the voltage into a voltage value that is a digital signal, and outputs the voltage value; a communication unit that performs digital communication with the welding power supply; Equipped with the communication unit transmits the voltage value input from the voltage detection unit to the welding power supply; Submerged arc welding system.

2. a wire feeder that feeds a welding wire and causes a tip portion of the welding wire to protrude from a tip of the welding torch as the electrode; The welding torch includes a contact tip that contacts the welding wire to pass a current therethrough, the voltage detection unit includes a first voltage detection line and a second voltage detection line; the first voltage detection line is conductively connected to the contact tip; the second voltage detection line is electrically connected to the workpiece; The submerged arc welding system of claim 1 .

3. The carriage includes a tire that is in contact with the workpiece, The second voltage detection line is conductively connected to the bogie.

3. The submerged arc welding system of claim 2.

4. The communication unit and the welding power supply are connected by a communication line and communicate with each other via CAN communication.

4. A submerged arc welding system according to claim 1.

5. The communication unit and the welding power supply communicate with each other via wireless communication.

4. A submerged arc welding system according to claim 1.

Images