Submerged arc welding machine and submerged arc welding method

Abstract

To provide a submerged arc welding with a submerged arc welding method that is able to keep an amount of wire deposition per unit length in a welding direction constant while controlling an arc length by means of feed variable speed control of a welding wire, thereby stabilizing welding.SOLUTION: A submerged arc welding method for welding a base material while moving a torch along a weld line of the base material, comprises: controlling an arc length by changing a feeding speed of a welding wire fed from the torch; determining a moving speed of the torch at which an amount of wire deposition per unit length along the welding line becomes constant; and controlling the moving speed of the torch, based on the determined moving speed.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a submerged arc welding machine and a submerged arc welding method. [Background technology]

[0002] A submerged arc welding method has been disclosed in which the arc length is controlled by variable feed speed control that changes the feed speed of the welding wire in response to the welding voltage (for example, Patent Document 1).

[0003] In variable feed speed control, the arc voltage, which indicates the arc length, is kept constant by successively changing the wire feed speed. In submerged arc welding using a thick wire, the wire melting rate is unlikely to change even if the welding current changes slightly, and it is difficult to obtain the self-regulation of the arc length that is generally used in GMA welding using a welding power source with constant voltage characteristics. Therefore, variable feed speed control is known to be effective for controlling the arc length. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-271944 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in variable feed speed control, the wire deposition amount per length in the welding direction changes with the change in the wire melting speed. The change in the wire deposition amount affects the leg length shortage and the layering plan. To avoid this, the wire feed speed needs to be constant, and in that case, a welding power source with constant voltage characteristics needs to be used to control the arc length by the self-regulation action of the arc length. However, as mentioned above, in submerged arc welding using a thick wire, it is difficult to obtain the self-regulation action of the arc length, and sufficient arc stability (welding stability) cannot be obtained.

[0006] An object of the present disclosure is to provide a submerged arc welding machine and a submerged arc welding method that can stabilize welding by controlling the arc length through variable welding wire feed speed control in submerged arc welding while maintaining a constant wire deposition amount per unit length in the welding direction. [Means for solving the problem]

[0007] A submerged arc welding machine according to one aspect of the present disclosure is a submerged arc welding machine that welds a base material while moving a torch along a weld line of the base material, and is equipped with a moving device that moves the torch along the weld line, a wire feeding device that feeds welding wire, a voltage sensor that detects a welding voltage corresponding to the arc length, and a control device, wherein the control device controls the arc length by changing the feeding speed of the welding wire by the wire feeding device based on the voltage detected by the voltage sensor, determines a moving speed of the torch at which the amount of wire deposition per unit length along the weld line is constant, and controls the moving speed of the torch by the moving device based on the determined moving speed.

[0008] A submerged arc welding method according to one aspect of the present disclosure is a submerged arc welding method in which a base material is welded while moving a torch along a weld line of the base material, the method controlling the arc length by changing the feed speed of a welding wire fed from the torch, determining a movement speed of the torch at which a constant amount of wire deposition per unit length along the weld line is achieved, and controlling the movement speed of the torch based on the determined movement speed. Effect of the Invention

[0009] According to one aspect of the present disclosure, in submerged arc welding, the arc length can be controlled by variable welding wire feed speed control to stabilize welding, while the wire deposition amount per unit length in the welding direction can be kept constant. [Brief description of the drawings]

[0010] [Figure 1]1 is a schematic diagram showing one configuration of a submerged arc welder according to an embodiment of the present invention; [Diagram 2] 1 is a block diagram showing one configuration of a submerged arc welder according to an embodiment of the present invention; [Diagram 3] 4 is a flowchart showing a control method according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Specific examples of the submerged arc welding machine and the submerged arc welding method according to the embodiments of the present disclosure will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0012] Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof. Fig. 1 is a schematic diagram showing one configuration of a submerged arc welding machine according to this embodiment, and Fig. 2 is a block diagram showing one configuration of the submerged arc welding machine according to this embodiment. The submerged arc welding machine according to this embodiment includes a welding power source 1, a control device 2, a torch 3, a wire reel 4, a wire feeder 5, a flux supply device 6, a carriage 7, a voltage sensor 8, and a current sensor 9. The submerged arc welding machine according to this embodiment is a welding system that can automatically adjust the carriage travel speed so that the wire deposition amount per weld cross section is constant.

[0013] The torch 3 is made of a conductive material such as a copper alloy, and has a cylindrical contact tip that guides the welding wire W to the part to be welded of the base metal A and supplies a welding current necessary to generate an arc. The contact tip comes into contact with the welding wire W that passes through its interior and supplies the welding current to the welding wire W.

[0014] The wire feeder 5 has a feed roller 51 that pulls out the welding wire W wound around the wire reel 4 and feeds it to the torch 3, and a motor 52 that rotates the feed roller 51. The wire feeder 5 supplies the welding wire W to the torch 3 by rotating the feed roller 51. The feed speed of the welding wire W is adjusted in accordance with the welding voltage so that the arc length does not fluctuate. The feed speed of the welding wire W by the wire feeder 5 is controlled by the control device 2.

[0015] The flux supply device 6 includes a flux hopper 61, a nozzle 62, a valve 63, a flux recovery machine (not shown), and the like. The flux hopper 61 stores flux B input from above, and the flux B is supplied to the part to be welded of the base material A through a nozzle 62 connected to the bottom of the flux hopper 61. The valve 63 opens and closes the path from the flux hopper 61 to the nozzle 62 to adjust the supply amount of flux B. The opening and closing and the opening and closing amount of the valve 63 are controlled by the control device 2. The opening and closing and the opening and closing amount of the valve 63 may be configured to be manually operated.

[0016] The cart 7 is a transport device that carries the welding power source 1, control device 2, torch 3, wire reel 4, wire feeder 5, flux supply device 6, etc., and moves along the welding line of the base material A. The cart 7 is equipped with a travel motor that rotates the wheels. The traveling cart 7 moves the torch 3 and flux supply device 6 along the welding line of the base material A, granular flux B stored in a flux hopper 61 is spread along the welding line, and welding wire W is fed into the flux B by the wire feeder 5. The travel speed of the cart 7 is controlled by the control device 2.

[0017] The voltage sensor 8 is a sensor that detects the voltage between an arc voltage detection lead wire attached to the torch 3 and an arc voltage detection lead wire attached to the base material A as a welding voltage (arc voltage) and outputs a voltage value signal indicating the detected voltage value to the control device 2.

[0018] The current sensor 9 is a sensor that detects the welding current that is supplied from the welding power source 1 via the torch 3 to the welding wire W and flows through the arc to the base material A, and outputs a current value signal indicating the detected current value to the control device 2.

[0019] The welding power source 1 is an inverter-controlled AC welding power source having constant current characteristics, and includes a rectifier 11, a primary inverter 12, a transformer 13, a rectifier 14, a DC reactor 15, and a secondary inverter 16, which are connected in series in this order from the input side of the commercial power source. The welding power source 1 is connected to the contact tip of the torch 3 and the base material A via a power supply cable. The welding power source 1 receives the commercial power source as input, and supplies welding power between the welding wire W and the base material A to generate an arc.

[0020] The rectifier 11 rectifies the AC current from the commercial power supply and outputs it to the primary inverter 12. The primary inverter 12 is driven at a high frequency of several tens of kHz to several tens of kHz, and provides the high-frequency AC current to the primary coil of the transformer 13. The transformer 13 transforms the AC current, and the transformed AC current is rectified by the rectifier 14 and output to the secondary inverter 16 via the DC reactor 15. The secondary inverter 16 is driven at a low frequency of several tens to several hundreds of Hz, and outputs the low-frequency AC current. The AC current output applies an AC welding voltage between the torch 3 and the base material A, and the welding current supplied from the welding power source 1 flows from the torch 3 to the welding wire W via the power cable. The base material A is welded by the heat of the arc generated between the base material A and the welding wire W by the welding current. The arc is covered with the flux B supplied by the flux supply device 6.

[0021] The control device 2 is a circuit that outputs control signals to each of the primary inverter 12 and the secondary inverter 16 of the welding power source 1, and digitally controls each inverter independently. The control device 2 also controls the feeding speed of the welding wire W by the wire feeding device 5, the supply amount of the flux B by the flux supply device 6, the traveling speed of the carriage 7, etc.

[0022] The control device 2 is a processor and includes an arithmetic processing unit 21 such as a CPU or a multi-core CPU, a memory unit 22, a setting reception unit 23, a wire feed speed control unit 24, a flux supply control unit 25, and a carriage travel speed control unit .

[0023] The storage unit 22 is a storage device including a non-volatile memory such as a Read Only Memory (ROM) and an EEPROM, and a volatile memory such as a Random Access Memory (RAM). The storage unit 22 includes a wire characteristics table in which the type of the welding wire W corresponds to the density of the welding wire W.

[0024] The setting reception unit 23 is an input device such as a button, key, dial, etc., and receives setting information including the set current of the submerged arc welding machine, the wire diameter of the welding wire W, the type of welding wire W, the deposition amount per unit length in the welding direction, and other welding conditions.

[0025] Wire feed speed control unit 24 is connected to a drive circuit of motor 52, and outputs a rotation control signal corresponding to the wire feed speed to the drive circuit, thereby controlling the feeding of welding wire W by wire feeder 5. Feeding roller 51 rotates at a speed corresponding to the rotation control signal, and welding wire W is fed to the portion to be welded of base material A via torch 3.

[0026] The arc length is proportional to the welding voltage (arc voltage). The welding voltage is the voltage between the contact tip of the torch 3 and the base material A, and is detected by the voltage sensor 8. A feed speed set value, which is a target value, is set in the wire feed speed control unit 24. The wire feed speed control unit 24 uses the feed speed set value and the average value of the welding voltage detected by the voltage sensor 8 (in the case of AC welding, this means the average value of the absolute value of the welding voltage) or the difference between the average value and the effective value as the manipulated variable, and controls the feed speed of the welding wire W so that the arc length is constant.

[0027] The flux supply control unit 25 is connected to a drive circuit that opens and closes the valve 63 of the flux supply device 6, and controls the supply of flux B by the flux supply device 6 by outputting an opening / closing signal to the drive circuit according to the amount of flux supply. Note that, in the case where the valve 63 is manually opened and closed, the flux supply control unit 25 is not necessary.

[0028] The bogie traveling speed control unit 26 is connected to a drive circuit that drives the traveling motor of the bogie 7, and controls the traveling of the bogie 7 by outputting a traveling control signal corresponding to the traveling speed of the bogie 7 to the drive circuit.

[0029] A voltage sensor 8, a current sensor 9, a primary inverter 12, and a secondary inverter 16 are connected to a signal input / output terminal (not shown) of the control device 2, and the primary inverter 12 is PWM controlled so as to operate with constant current characteristics based on the set welding conditions and the detected welding current and welding voltage. A required welding voltage is applied between the base material A and the welding wire W, and a welding current flows between them.

[0030] The wire feed speed control unit 24 and the carriage traveling speed control unit 26 described above enable the wire deposition amount per unit length in the welding direction to be kept constant while controlling the arc length by controlling the variable feed speed of the welding wire W to stabilize welding.

[0031] The wire deposition amount per length in the welding direction is calculated by dividing the wire feed weight per unit time by the welding speed. That is, the wire deposition amount is proportional to the wire feed speed and inversely proportional to the welding speed (travel speed of the carriage 7).

[0032] Therefore, while applying the variable feed speed control, the carriage travel speed control unit 26 changes the travel speed of the carriage 7 so that the feed speed / travel speed becomes a constant value. More specifically, the carriage travel speed control unit 26 sequentially changes the travel speed so that the wire deposition amount per unit length, i.e., wire cross-sectional area×wire feed speed×wire density / travel speed=set value of the wire deposition amount per length in the welding direction, becomes true. This operation makes it possible to perform stable submerged arc welding by controlling the variable feed speed while maintaining a constant wire deposition amount per length in the welding direction.

[0033] 3 is a flowchart showing a control method according to this embodiment. In the following description, arc length control and travel speed control will be mainly described, and other details of arc welding control will be omitted or simplified. The control device 2 receives setting information including a set current of the submerged arc welding machine, a wire diameter of the welding wire W, a type of the welding wire W, a deposition amount per unit length in the welding direction, and other welding conditions (step S11), and starts submerged arc welding control (step S12).

[0034] Next, the control device 2 detects the welding voltage by the voltage sensor 8 (step S13). Then, the control device 2 determines the wire feed speed based on the difference between the average value or effective value of the detected welding voltage and the set voltage (step S14), and performs variable speed control of the feeding of the welding wire W by the determined wire feed speed (step S15). The set voltage is the voltage when the arc length is a predetermined length. By matching the welding voltage with the set voltage, the arc length can be kept constant. The control device 2 determines the forward or reverse rotation of the motor 52 based on the sign of the difference voltage between the detected welding voltage and the set voltage, and also determines the wire feed speed based on the value of this difference voltage. Specifically, the control device 2 increases the wire feed speed when the difference voltage of (detected welding voltage)-(set voltage) is positive, and decreases the wire feed speed when the difference voltage of (detected welding voltage)-(set voltage) is negative.

[0035] Next, the control device 2 specifies the cross-sectional area and density of the welding wire W based on the wire diameter and type of the welding wire W received in step S11. The cross-sectional area of ​​the welding wire W can be calculated from the wire diameter received in step S11. In addition, the density of the welding wire W can be specified by referring to a wire characteristics table using the type of the welding wire W received in step S11 as a key.

[0036] Then, based on the wire deposition amount set in step S11, the feed speed of the welding wire W determined in step S14, and the cross-sectional area and density of the welding wire W specified in step S17, the control device 2 determines the traveling speed of the carriage 7 so that the wire deposition amount per unit length along the weld line is constant (step S16), and performs variable speed control of the traveling speed of the carriage 7 (step S17).

[0037] Specifically, the control device 2 determines the traveling speed of the carriage 7 based on the following formula (1).

[0038] Sw × Vw × ρ / v = Q … (1) however, Sw: Cross-sectional area of ​​welding wire W Vw: Welding wire W feed speed ρ: Density of the welding wire W v: Travel speed of cart 7 (travel speed of torch 3) Q: Wire deposition amount

[0039] Thereafter, the control device 2 determines whether or not a predetermined end condition is satisfied (step S18), and if the end condition is satisfied (step S18: YES), ends the welding process. If the end condition is not satisfied (step S18: NO), the control device 2 repeatedly executes the processes of steps S12 to S17 to execute the submerged arc welding method.

[0040] (Example) An example of the submerged arc welding method according to this embodiment will be described. The welding wire W was an iron wire with a wire diameter of 4.8 mm (density 7.87 g / cm 3 ) was used, the welding current was set to 800 A, the wire deposition rate per cm of length in the welding direction was set to 3.56 g / cm, and variable feed speed control was applied to perform submerged arc welding. In this case, the running speed (cm / min) = 0.24 (cm) x 0.24 (cm) x π x 7.87 (g / cm 3) × feed speed (m / min) × 100 / 3.56 (g / cm) = 40 × feed speed (m / min). For example, when the feed speed is 1 m / min, the travel speed is 40 cm / min. When the feed speed is 2 m / min, the travel speed is 80 cm / min.

[0041] As described above, according to the submerged arc welding machine and the submerged arc welding method of this embodiment, the arc length is controlled by variable feed speed control of the welding wire W to stabilize welding, while the wire deposition amount per unit length in the welding direction can be kept constant.

[0042] Instead of the wire deposition amount per length in the welding direction, other indices, such as the wire deposition area per cross section perpendicular to the welding direction, may be used as an index for controlling the feed speed.

[0043] Although the dolly 7 has been described as an example of a moving device for moving the torch 3, a welding robot may be used as the moving device to control the moving speed of the torch 3. [Explanation of symbols]

[0044] 1: welding power source, 2: control device, 3: torch, 4: wire reel, 5: wire feeder, 6: flux supply device, 7: cart, 8: voltage sensor, 9: current sensor, 21: calculation processing unit, 22: memory unit, 23: setting reception unit, 24: wire feed speed control unit, 25: flux supply control unit, 26: cart travel speed control unit, A: base material, B: flux, W: welding wire

Claims

1. A submerged arc welding machine that welds a base metal while moving a torch along a weld line of the base metal, A moving device that moves the torch along the weld line; a wire feeder that feeds a welding wire; a voltage sensor for detecting a welding voltage corresponding to an arc length; Control device and Equipped with The control device includes: a supply speed of the welding wire by the wire feeder is changed based on the voltage detected by the voltage sensor to control the arc length; determining a travel speed of the torch at which a constant amount of wire deposition per unit length along the weld line is achieved; The moving speed of the torch by the moving device is controlled based on the determined moving speed. Submerged arc welding machine.

2. The control device determines the moving speed of the torch based on the following formula:

2. The submerged arc welder according to claim 1. Sw×Vw×ρ / v=Q however, Sw: Cross-sectional area of ​​the welding wire Vw: the feed speed of the welding wire ρ: density of the welding wire v: the moving speed of the torch Q: The amount of wire deposition

3. a setting receiving unit that receives setting information related to a cross-sectional area of ​​the welding wire, a density of the welding wire, and a wire deposition amount, The control device includes: determining a feed speed of the welding wire based on the voltage detected by the voltage sensor; A moving speed of the torch is determined based on the determined feeding speed of the welding wire, the cross-sectional area of ​​the welding wire, the density of the welding wire, and the wire deposition amount based on the setting information received by the setting reception unit.

3. A submerged arc welder as claimed in claim 2.

4. The moving device is A cart that carries the torch and moves the torch along the weld line of the base material. The submerged arc welding machine according to any one of claims 1 to 3.

5. A submerged arc welding method for welding a base metal while moving a torch along a weld line of the base metal, comprising the steps of: Controlling the arc length by varying the feed speed of the welding wire fed from the torch; determining a travel speed of the torch at which a constant amount of wire deposition per unit length along the weld line is achieved; The moving speed of the torch is controlled based on the determined moving speed. Submerged arc welding method.

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