Submerged arc welding machine and submerged arc welding method

Abstract

To provide a submerged arc welding method that can manually adjust responsibility of a wire feeding speed for arc length change in submerged arc welding for controlling an arc length by feeding variable speed control.SOLUTION: A submerged arc welding method receives setting of a gain of responsibility of welding wire feeding speed change for arc length change, detects a welding voltage corresponding to an arc length, changes the welding wire feeding speed on the basis of the detected voltage, thereby controlling the arc length, and changes the welding wire feeding speed on the basis of a prescribed voltage corresponding to a prescribed arc length and the received gain, thereby controlling the arc length.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 can be 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.

[0004] The variable feed speed control operates to determine the feed speed or the feed speed correction amount according to, for example, the effective value or average value of the welding voltage (arc voltage), or according to the difference between the set voltage and the effective value or average value of the welding voltage. If the effective value or average value of the welding voltage is large, or if the effective value or average value of the welding voltage is large relative to the set voltage, this indicates that the arc length is large. In this case, the feed speed is adjusted to increase the feed speed, thereby shortening the arc length and controlling the effective value or average value of the welding voltage, which is correlated with the arc length, to be smaller. The same is true inversely. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-271944 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned control, the larger the change in the feed speed relative to the change in the voltage, the larger the operation amount of the feed speed becomes, and the smaller the change in the effective value or average value of the welding voltage, which indicates the arc length, becomes. However, if the change in the feed speed relative to the change in the voltage is too large, a so-called high gain state occurs, and the feed speed and the effective value or average value of the welding voltage oscillate, making the welding unstable. In addition, even if vibration does not occur, the larger the change in the feed speed, the faster the wear rate of the equipment around the wire feed, such as the feed gear and the tip, becomes.

[0007] In the conventional analog feed control device for submerged arc welding, changing the voltage adjustment scale or the gear ratio for feeding corresponds to changing the responsiveness of the feed speed according to the voltage information as described above. However, in the feed device, it is not possible to change only the responsiveness of the feed speed, and the feed speed and the convergence value of the effective or average value of the voltage also change at the same time. The convergence value of the effective or average value of the voltage is one of the most important factors in adjusting the welding conditions, and the convergence value of the effective or average value of the voltage is adjusted with the highest priority so that stable welding can be performed and the desired arc length and penetration depth can be obtained. The responsiveness of the feed speed according to the voltage information described above is only determined as a result. In other words, in the conventional welding system, the responsiveness of the feed speed cannot be independently operated.

[0008] An object of the present disclosure is to provide a submerged arc welding machine and a submerged arc welding method that enable manual adjustment of the responsiveness of the wire feed speed to changes in arc length (changes in welding voltage) in submerged arc welding in which the arc length is controlled by variable feed speed control. [Means for solving the problem]

[0009] A submerged arc welding machine according to one aspect of the present disclosure includes a wire feeding device that feeds welding wire, a voltage sensor that detects a welding voltage corresponding to an arc length, a control device that controls the arc length by changing a feeding speed of the welding wire by the wire feeding device based on the welding voltage detected by the voltage sensor, and a setting reception unit that receives a setting of a gain that indicates the responsiveness of a change in the feeding speed of the welding wire to a change in the arc length, and the control device determines the feeding speed of the welding wire by the wire feeding device based on the welding voltage detected by the voltage sensor, a predetermined voltage corresponding to a predetermined arc length, and the gain received by the setting reception unit.

[0010] A submerged arc welding method according to one aspect of the present disclosure receives a gain setting indicating the responsiveness of a change in a welding wire feed speed to a change in arc length, detects a welding voltage corresponding to the arc length, and controls the arc length by changing the welding wire feed speed based on the detected welding voltage, a predetermined voltage corresponding to a predetermined arc length, and the received gain. Effect of the Invention

[0011] According to one aspect of the present disclosure, in submerged arc welding in which arc length is controlled by variable feed speed control, the responsiveness of the wire feed speed to changes in arc length can be manually adjusted. [Brief description of the drawings]

[0012] [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

[0013] 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.

[0014] 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 feeder 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 in which a user can manually adjust the adjustment amount (gain) of the wire feed speed relative to the difference between a set voltage and a welding voltage.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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 .

[0025] 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 also stores a proportional gain related to the responsiveness of the variable feed speed control.

[0026] The setting reception unit 23 is an input device such as a button, key, or dial, 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 the welding wire W, a proportional gain related to the responsiveness of the variable feed speed control, and other welding conditions. The proportional gain is a numerical value indicating the responsiveness of the change in the feed speed of the welding wire W to the change in the arc length. More specifically, the proportional gain indicates the relationship between the amount of change in the feed speed of the welding wire W relative to the difference between the average value (in the case of AC welding, this means the average value of the absolute value of the welding voltage) or the effective value of the welding voltage detected by the voltage sensor 8 and the set voltage (predetermined voltage) corresponding to a predetermined arc length.

[0027] 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.

[0028] 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 controls the feed speed of the welding wire W so that the arc length is constant, using the difference between the feed speed set value and the average or effective value of the welding voltage detected by the voltage sensor 8 as the manipulated variable.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] The wire feed speed control unit 24 described above makes it possible to stabilize welding by controlling the arc length through variable speed control of the feed of the welding wire W. In particular, the submerged arc welder according to this embodiment is configured so that the user can manually adjust the responsiveness of the wire feed speed in response to the welding voltage, and in particular employs a proportional gain that is easy for the user to understand as a parameter for adjusting the responsiveness.

[0033] For example, consider a case where the average value of the welding voltage (in the case of AC welding, this means the average value of the absolute value of the welding voltage) is fed back, and the feed speed is PI controlled so that the difference between this value and the set voltage becomes small. In this case, the parameters that control the feed responsiveness include the proportional (P) gain and the integral (I) gain. In addition, the time over which the average value of the welding voltage is taken (taking a moving average of n AC cycles, taking the total average from the start of welding to the present, etc.) and the control period (the update period of the feed speed command value) are also parameters that control the feed responsiveness. Of these parameters, the effect of the proportional (P) gain is relatively easy to understand. If the proportional (P) gain is adjusted to a larger value, the change in feed speed will be larger and the change in voltage will be smaller. If the gain is adjusted to a smaller value, the change in feed speed will be smaller and the change in voltage will be larger. On the other hand, it is not easy for general users to understand the meaning of each parameter for the latter three, making adjustments difficult. Therefore, a submerged arc welding system is provided in which the proportional (P) gain is treated as a parameter with a name and meaning such as "feed response" and the user is allowed to adjust only this parameter. This allows the user to adjust the feed response to an optimal value according to the situation.

[0034] 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 welder, a wire diameter of the welding wire W, a type of the welding wire W, a proportional gain related to the responsiveness of variable feed speed control, and other welding conditions (step S11), and starts submerged arc welding control (step S12).

[0035] Next, the control device 2 detects the welding voltage using 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 a set voltage (predetermined voltage) (step S14).

[0036] Then, the control device 2 performs variable speed control of the feeding of the welding wire W based on the determined wire feeding speed (step S15). Specifically, the control device 2 performs PI control using the proportional gain received in step S11 and a predetermined integral gain so that the average or effective value of the detected welding voltage approaches a set voltage as a target voltage. The integral gain is a fixed value set in the control device 2 in advance.

[0037] The set voltage is the voltage when the arc length is a predetermined length. The arc length can be kept constant by matching the average or effective value of the welding voltage with the set voltage. The control device 2 determines whether the motor 52 rotates forward or backward depending on the sign of the difference voltage between the average or effective value of the detected welding voltage and the set voltage, and also determines the wire feed speed depending on the value of this difference voltage. Specifically, the control device 2 increases the wire feed speed when the difference voltage (the average or effective value of the detected welding voltage) - (the set voltage) is positive, and decreases the wire feed speed when the difference voltage (the average or effective value of the detected welding voltage) - (the set voltage) is negative. The amount of increase or decrease in the wire feed speed relative to the difference voltage is proportional to the value of the proportional gain.

[0038] Thereafter, the control device 2 determines whether or not a predetermined end condition is satisfied (step S16), and if the end condition is satisfied (step S16: YES), ends the welding process. If the end condition is not satisfied (step S16: NO), the control device 2 repeatedly executes the processes of steps S12 to S15 to execute the submerged arc welding method.

[0039] As described above, according to the submerged arc welding machine and submerged arc welding method of the present embodiment, in submerged arc welding in which the arc length is controlled by variable feed speed control, the responsiveness of the wire feed speed to changes in arc length can be manually adjusted.

[0040] In the present embodiment, an example has been described in which a proportional gain is received to adjust the responsiveness of the wire feed speed to changes in arc length. However, the configuration may also be such that the user is allowed to operate or select a combination of multiple pre-prepared operating parameters, such as changing the proportional (P) gain and the integral (I) gain in conjunction with each other.

[0041] The method of feed control is not limited to the above-mentioned PI control, and may be configured to control by PD control, PID control, or other known methods. The differential gain in the PD control and PID control is also set to a fixed value, similar to the integral gain.

[0042] Furthermore, the operational parameters that determine the responsiveness of the wire feed speed to changes in the arc length are not limited to those described above. [Explanation of symbols]

[0043] 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 wire feeder that feeds a welding wire; a voltage sensor for detecting a welding voltage corresponding to an arc length; a control device that controls an arc length by changing a feeding speed of the welding wire by the wire feeder based on the welding voltage detected by the voltage sensor; a setting receiving unit that receives a setting of a gain indicating a responsiveness of a change in a feed speed of the welding wire to a change in an arc length; Equipped with The control device includes: A feeding speed of the welding wire by the wire feeder is determined based on the welding voltage detected by the voltage sensor, a predetermined voltage corresponding to a predetermined arc length, and the gain received by the setting reception unit. Submerged arc welding machine.

2. The gain is a proportional gain indicating a relationship between a difference between an average value or an effective value of the welding voltage detected by the voltage sensor and a predetermined voltage corresponding to a predetermined arc length and a change in the feed speed of the welding wire 2. The submerged arc welder according to claim 1.

3. A submerged arc welding method comprising the steps of: receiving a setting of a gain indicating a responsiveness of a change in a feed speed of the welding wire to a change in an arc length; Detecting the welding voltage corresponding to the arc length; The arc length is controlled by changing the feed speed of the welding wire based on the detected welding voltage, a predetermined voltage corresponding to a predetermined arc length, and the received gain. Submerged arc welding method.

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