JP3354102B2 - Welding sub-controller, welding machine and welding system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a welding sub-controller, a welding machine, and a welding system used for arc welding.

[0002]

2. Description of the Related Art A general arc welding machine has a structure in which a wire feeding device is connected to a wire feeding cable end and a welding power source is connected to a power cable end among various cables extending from a torch. Has become. During the welding operation, electric power for arc generation is supplied from the welding power source to the torch, and the main motor provided in the wire supply device is driven by the welding power source, so that the wire serving as the molten material is sent to the torch side. Be paid. Incidentally, such an arc welding machine is disclosed in JP-A-61-222682 and the like.

[0003]

In recent years, there has been an increasing demand for a method of using cables that extend from the torch so that the torch can be moved over a wide range away from the wire supply device. In particular, in a system in which a torch is mounted on a robot for automation, in order to reduce the load on the robot, etc., the above-described method is used in order to install a wire supply device conventionally mounted on the robot at a location away from the robot. Request is strong.

However, when the length of the wire feeding cable between the torch and the wire feeding device becomes longer, the feeding resistance when feeding the wire to the torch increases. On the other hand, a technology has been developed in which a small motor is built into the torch itself so that a wire can be drawn into the torch.However, in a conventional welding machine, a power line of the small motor is provided in, for example, a robot controller. Small power supply (for example, one with a constant voltage of 12V)
And operated only on / off based on the start / stop of the main motor. For this reason,
Even if the curvature of the wire feed cable changes and the feed resistance of the wire increases, the submotor can only pull the wire with the same force, causing variations in the amount of wire extending from the tip of the torch and adversely affecting welding quality. Was exerted. Also,
When the power cable between the torch and the wire supply device is lengthened, the voltage drop between both ends may become a value that adversely affects welding quality. However, conventional welding machines have not been provided with a means for compensating for this voltage drop.

The present invention has been made in view of the above circumstances, and has a welding sub-controller and a welding sub-controller capable of moving a torch over a wide range away from a wire feeder and improving welding quality. Machine and welding system.

[0006]

To achieve the above object, a welding sub-controller according to the first aspect of the present invention comprises:
A welding sub-controller for cooperating a main motor capable of feeding a wire serving as a material to the torch for arc welding and a sub-motor provided integrally with the torch and capable of drawing the wire into the torch. The rotation speed of the main motor is fed back and compared with the set speed, and the main motor is controlled at a constant speed based on a voltage command value that causes the rotation speed to reach the set speed. The drive power according to the voltage command value applied to the main motor, the drive power being offset from the drive power supplied to the main motor is a rotational speed fan.
It is characterized in that it is supplied without performing feedback control and that an offset amount adjusting means is provided.

[0007]

According to a second aspect of the present invention, there is provided a welding machine which is provided integrally with a main motor capable of feeding a wire serving as a melting material to a torch for arc welding, and which can draw the wire into the torch. A sub motor and a welding power source that supplies electric power for arc generation to the torch and supplies driving power to the main motor, the rotation speed of the main motor is fed back, and this is set to a set speed. In comparison, the motor is configured to be controlled at a constant speed based on a voltage command value that causes the rotation speed to reach the set speed, and is a drive power that is supplied to the sub-motor according to the voltage command value given to the main motor. The drive power offset from the drive power supplied to the motor is the rotational speed
The present invention is characterized in that a sub motor control means that operates so as to be supplied without performing the degree feedback control and an offset amount adjusting means are provided.

[0009] Welding machine according to the invention of claim 3, claim 2
In serial mounting of the welder, between the welding power source and the torch,
A power cable for transmitting electric power for arc generation is insulated from the wire and extended, and the end of the power cable and the end of the wire are short-circuited in the torch, and the voltage between both ends of the power cable is A voltage drop compensating means for detecting the voltage drop and compensating the welding power source for the voltage drop based on the detection result is provided, and the voltage drop compensating means is provided with a pair of potential detectors. Is connected to the base end of the power cable to detect the potential of the base end of the power cable, and the other potential detection unit is connected to the base end of a wire short-circuited at the end of the power cable. The feature is that the potential of the tip of the power cable is detected using the fact that the voltage drop of the wire is almost equal to that of the power cable. That.

According to a fourth aspect of the present invention, there is provided a welding system in which a torch for arc welding, in which a wire serving as a melting material can be drawn by integrally providing a sub-motor, is attached to the tip of a robot, and the wire is fed toward the torch. In order to arrange the main motor for feeding away from the robot and to make the sub motor and the main motor cooperate,
The rotation speed of the main motor is fed back, the speed is compared with a set speed, and the main motor is controlled so as to be controlled at a constant speed based on a voltage command value that causes the rotation speed to reach the set speed. The driving power according to the voltage command value given to the motor, the driving power being offset from the driving power supplied to the main motor.
The present invention is characterized in that a sub motor control unit that operates so as to be supplied without performing the rotational speed feedback control and an offset amount adjusting unit are provided.

[0011]

<Operation and effect of the invention><Invention of claim 1> By setting the welding sub-controller in the welding machine, the rotation speed of the main motor is fed back, and when the rotation speed is about to decrease, the amount is reduced. The corrected drive power is supplied to the main motor to compensate for the lack of torque. On the other hand, for the sub motor, the driving power based on the voltage command value corrected in the constant speed control of the main motor is supplied. As a result, the sub motor is driven in conjunction with the main motor, and when the feed resistance of the wire fluctuates, the loads can be shared by both motors, so that the wire is stably sent to the tip of the torch. Be paid. Accordingly, high quality welding can be performed even when the cables extending from the torch are lengthened to increase the movable range of the torch and the wire feeding resistance increases. Moreover, the sub motor is larger than the main motor
Want to send wire faster and vice versa
Can be handled by operating the adjustment means.
You.

[0012]

<Invention of Claim 2 > The rotation speed of the main motor is fed back by the sub motor control means provided in the welding machine, and when the rotation speed is about to decrease, the driving power corrected for the rotation speed is supplied to the main motor. To compensate for the lack of torque. On the other hand, for the sub motor, the driving power based on the voltage command value corrected in the constant speed control of the main motor is supplied. Thereby, when the sub motor is driven in conjunction with the main motor and the feed resistance of the wire fluctuates, the loads can be shared by both motors,
Thus, the wire is stably fed to the tip of the torch. Accordingly, high quality welding can be performed even when the cables extending from the torch are lengthened to increase the movable range of the torch and the wire feeding resistance increases. And sub
Set the motor to feed wires faster than the main motor
Operating the adjustment means if you want
It can be handled by doing.

<Invention of Claim 3 > Since the voltage drop of the power cable is compensated by the voltage drop compensation circuit, the welding operation can be performed with a stable welding voltage, and the welding quality is improved. Here, the pair of potential detectors provided in the voltage drop compensating circuit are originally connected to the base end of the front end of the power cable, but in the present invention, one potential detector is connected to the base end of the power cable. , And the other potential detecting section is connected to the proximal end of the wire. This means that the wire has a voltage drop equal to that of the power cable, and that the wire and the power cable are short-circuited in the torch so that the entire wire is at the same potential as the power cable at the end. This makes it possible to detect the potential at the tip of the power cable without extending the potential detection unit to the tip of the power cable, thereby simplifying the cables connected to the torch.

[0015] the sub motor control means provided in the welding system <invention of claim 4>, for the main motor, the rotational speed is fed back, when the rotation speed is about to fall driving power to correct the minute main motor To compensate for the lack of torque. On the other hand, for the sub motor, the driving power based on the voltage command value corrected in the constant speed control of the main motor is supplied. In this way, when the sub motor is driven in conjunction with the main motor and the feed resistance of the wire fluctuates, the loads can be shared by both motors, so that the wire is stably fed to the tip of the torch. .
Accordingly, high quality welding can be performed even when the cables extending from the torch are lengthened in order to dispose the main motor in a place different from the robot and the wire feeding resistance increases. In addition, the sub motor is faster than the main motor.
If you want to set up a feeder and vice versa,
It can be handled by operating the adjusting means.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> A first embodiment of the present invention will be described below with reference to FIGS. In the welding machine 10 of the present embodiment, the entire wiring is shown in FIG. 1, and a welding sub-controller 11 (hereinafter simply referred to as “sub-controller 11”) to which the present invention is applied is provided with an existing welding power source 12 and a welding power source 12. And connected to the torch 13 for use. The welding machine 10 performs arc welding by a so-called MIG method. Torch 1
2 is shown in an enlarged manner in FIG. 2 and includes a handle portion 15 below a base portion 14 to which various cables are connected, and a torch main body 16 extending forward from the base portion 14 is bent in the middle. It has a structure in which the tip side extends obliquely downward. The supply path of the wire W serving as the melting material is
4 penetrates back and forth and opens at the tip through the shaft portion of the torch body 16, and the wire W inserted therethrough
Extend from the tip of the torch 13.

As shown in FIG. 1, one end of a power cable 17 is connected to the torch 13 and short-circuited to a wire W in the torch 13, and the other end of the power cable 17 is connected to a wire supply device 18 described later. Intermediary stand 19 provided integrally
Is connected to an extension power cable 17A extending from the welding power source 12 through the power supply. Further, a jig-side power cable 42 extending from a jig 41 for holding the welding object 40 is connected to the welding power source 12, whereby the tip of the wire W extending from the tip of the torch and the welding object are connected. Thing 40
And a wire W melted by the arc becomes a bead for joining the welding target 40. Then, the consumed wires W are sequentially sent out to the tip of the torch 13.

The power cable 17 has a longer overall length than a general cable (for example, 10 m in length) so that the torch 13 can be moved over a wide range away from the wire supply device 18. ing). Further, the lengthening increases the voltage drop between both ends of the power cable 17, and a voltage drop compensation circuit 30 for compensating for the voltage drop is provided in the sub-controller 11, which will be described in detail later.

The torch 13 is connected to a gas pipe 20A extending from a supply cylinder 20 for an inert gas (eg, argon, nitrogen, etc.). And the gas pipe 20A
When the solenoid valve 20B provided in the middle of the torch is opened based on a command from the welding power source 12, the inert gas is discharged from the tip of the torch 13 through a gas supply path (not shown) provided in the torch main body 16. Covers the arc and prevents oxidation of the molten bead.

Further, a wire feeding cable 22 is connected to the torch 13, and a wire W is passed through a shaft core portion thereof and supplied to the torch 13. Then, at the base end of the wire feeding cable 22 opposite to the torch 13,
A wire supply device 18 for feeding the wire W toward the torch 13 is connected. The wire supply device 18
FIG. 3 is an enlarged view showing a flat DC motor 24.
(Hereinafter referred to as “main motor 24”),
The wire W is sandwiched between a driving pulley 25 fitted to the driving shaft of the main motor 24 and an interlocking pulley 26 pressed against the driving pulley 25 and interlockingly rotating. When the main motor 24 is driven, the driving pulley 25
The wire W is sent toward the torch 13 at the same speed as the tangential speed of the wire W. The main motor 24 has a built-in tacho generator (hereinafter simply referred to as a "tacho generator") for detecting a rotation speed, and its output signal line 26T
And the motor power line 26P are both connected to a motor drive circuit 28 provided in the welding power source 12 (see FIGS. 1 and 4).

The wire feeding cable 22 is also longer than a general cable (corresponding to the power cable 17) (for example, the total length is 10 m). In consideration of the increase in the supply resistance of the wire W due to this, the torch 13 has a built-in small DC motor 33 (hereinafter, referred to as a “sub motor 33”) for drawing the wire W into the torch 13. More specifically, as shown in FIG. 2, the main body 33A of the sub motor 33 is housed in the handle portion 15, and the drive shaft 33B protrudes from the base 14 beside the wire supply path. A wire W is sandwiched between a driving pulley 34 fitted to 33 </ b> B and an interlocking pulley 35 rotatably provided on the base 14. When the sub motor 33 is driven, the wire W is sent in the axial direction at the same speed as the tangential speed of the driving pulley 34. The power line 37 of the sub motor 33 is connected to a sub motor drive circuit 38 provided in the sub controller 11, as shown in FIG.

A switch 36 is provided on the front surface of the base end of the handle portion 15 of the torch 13. The signal line 36A of this switch is connected to the main control circuit 29 provided in the welding power source 12. The cables (the power cable 17, the wire feed cable 22, the gas pipe 20A, the motor wire 37, and the signal wire 36A) between the torch 13 and the wire supply device 18 are bundled into one and taken out. The circulation is facilitated, and the cable is cooled particularly through the power cable 17 in the gas pipe 20A.

As shown in FIG. 1, a welding power supply 12 includes a main power supply circuit 27 for supplying electric power for arc generation and a main motor driving circuit 2 for driving the main motor 24.
8 and a main control circuit 29 for integrally controlling these. The desired welding conditions (welding voltage, wire feed speed, etc.) set by an adjustment knob (not shown) provided on the front panel of the welding power source 12 are transmitted to the main control circuit 29.
Through the respective circuits 27 and 28.

The main motor drive circuit 28 is shown as a block diagram in the lower part of FIG.
And a power supply circuit 28B, and controls the rotation speed of the main motor 24 by voltage control. Here, the relationship between the wire feed speed and the voltage value to be applied to the main motor 24 for that purpose is basically proportional as shown in FIG. 5 from the characteristics of the motor, the pulley ratio, and the like. The command circuit 28C provided in the control circuit 28A outputs a basic voltage command value S2 to be applied to the main motor 24, based on the wire feed speed set value S1 (see FIG. 4).
Further, the motor rotation speed S3 is fed back to the control circuit 28A, and the correction circuit 28D provided in the control circuit 28A determines the amount by which the motor rotation speed deviates from the set value due to the change in the feeding resistance of the wire W. Is the correction voltage command value S4
Output as Then, a voltage command value S5 obtained by adding the basic voltage command value S2 and the correction voltage command value S4 is input to the power supply circuit 28B, and based on this, the power supply circuit 28B applies a predetermined voltage to the main motor 24.

On the other hand, the main control circuit 29 is shown in the block diagram of FIG. 6, and includes a command circuit 29A for outputting a basic voltage command value L2 based on the set value L1 of the welding voltage, a relay circuit for the main power supply circuit 27, Extension power cable 17 between base 19
And a compensation circuit 29B that outputs a compensation voltage command value L3 based on the voltage drop of A. By the way, the welding power supply 12 is not provided with a compensation circuit for a voltage drop from the relay stand 19 to the torch 13 as in a general welding power supply. Therefore, in the welding machine 10 of the present embodiment, the voltage drop compensation circuit 30 provided in the sub-controller 11 is connected to the main control circuit 29 of the welding power supply 12. The sub-correction command value L output from the voltage drop compensation circuit 30
4 and a voltage command value L5 combined with the command values L2 and L3.
Are drawn into the main power supply circuit 27.

As shown in FIG. 1, the sub-controller 11 includes a sub-motor driving circuit 38 for driving the sub-motor 33 and the above-mentioned voltage drop compensating circuit 30. As shown in the upper part of FIG. 4, the sub motor drive circuit 38 includes a control circuit 38A and a power supply circuit 38B. The control circuit 38A further includes a command circuit 38C and a correction circuit 38D. Then, the voltage command value S5 in the main motor drive circuit 28 is drawn into the command circuit 38C. Here, the sub motor 33
The relationship between the wire feed speed and the voltage value to be applied to the sub motor 33 for this purpose is basically proportional to the motor characteristics and the pulley ratio as shown in FIG. Due to the difference from the characteristics of the motor 24 and the like, the voltages for making the two motors 24 and 33 have the same wire feed speed are offset from each other. Then, based on this relationship and the voltage command value S5 drawn from the main motor drive circuit 28, the command circuit 38C outputs a basic voltage command value T1 to be applied to the sub motor 33. The current value T2 of the power transmitted from the power supply circuit 38B to the sub motor 33 is fed back to the control circuit 38A. Here, generally, the relationship between the current value and the rotation speed of the motor has a more linear relationship than the relationship between the voltage value and the rotation speed of the motor. Utilizing this, the correction circuit 38D provided in the control circuit 38A outputs a correction voltage command value T3 based on the fed back current value T2. Then, a voltage command value T4 obtained by adding the basic voltage command value T1 and the correction voltage command value T3 is input to the power supply circuit 38B, and the power supply circuit 38B supplies power of a predetermined voltage value to the sub motor 33. The sub-controller 11 is provided with an offset adjuster 38E. By operating the offset adjuster 38E, a command circuit for the basic offset voltage value V1 of the main motor 24 and the sub-motor 33 shown in FIG. 3
The basic voltage command value T1 output by 8C can be adjusted to be large or small.

On the other hand, as shown in FIG. 6, the voltage drop compensation circuit 30 includes a pair of potential detection lines 31 and 32 for detecting a voltage drop of the power cable 17 between the torch 13 and the relay stand 19. Have. Then, the voltage drop compensating circuit 30 detects the welding power source 12 based on the detection result of the voltage drop.
Is output to the main control circuit 29 of the welding power supply 12 as a sub-correction command value L4. Here, the two potential detection lines 31 and 32 are originally connected to the distal end and the base end of the power cable 17, but in the present embodiment, as shown in FIG. 1 and FIG. 31 is connected to the base end of the power cable 17 (fixed portion to the relay stand 19), and the other potential detection line 32
Of the wire W is slidably connected to an exposed portion of the wire W passing near the relay stand 19. This is the wire W
Means that the voltage drop is substantially equal to that of the power cable 17 and the wire W and the power cable 17 are connected to the torch 1
3 is used because the whole wire W is equal to the potential on the distal end side of the power cable 17. Thereby, the potential at the tip of the power cable 17 can be detected without extending the potential detection line to the tip of the power cable 17, and the cables connected to the torch 13 can be simplified.

Next, the operation of the welding machine 10 according to the present embodiment having the above configuration will be described. To perform a welding operation,
A start switch (not shown) of the welding power source 12 is turned on, and the welding condition is set to a desired value by adjusting knob or the like. Then, the tip of the torch 13 is connected to the welding object 40 (FIG. 1).
When the switch 36 provided on the handle portion 15 of the torch 13 is turned on toward the torch 13, this is a start command, and the circuits 27, 28, 29 of the welding power source 12 are driven, and the driven welding power source is driven. The voltage designation value S5 (see FIG. 4) of the main motor drive circuit 28 of FIG.
Is driven. Then, by driving the main power supply circuit 27,
An arc generating voltage is applied between the torch 13 and the welding target 40, and the main motor drive circuit 28 and the sub motor drive circuit 38 drive the main motor 2.
4 and the sub motor 33 start rotating at the same timing,
The wire W extends from the tip of the torch 13. Thereby, the tip of the wire W gradually approaches the welding target 40,
An arc is generated at a predetermined distance. Then, the wire W melted by the arc is applied to the welding object 40.
And the consumed wire W is sequentially sent to the tip of the torch 13. The switch 36
Is turned on, the main control circuit 29 of the welding power source 12 opens the solenoid valve 20B provided in the middle of the gas pipe 20A, and the inert gas covers the arc.

By the way, at the welding site, the temperature is low at the start of work and high in the daytime due to the effect of being provided indoors with poor ventilation, which is often affected by heat from welding. . For this reason, the electric resistance value of the power cable 17 changes, and the value of the voltage drop also changes greatly. In particular, when the power cable 17 is set to be long as in the present embodiment, the degree of change in the voltage drop is large. However, in the welding machine 10 of the present embodiment, the voltage drop of the power cable 17 is detected by the voltage drop compensation circuit 30 provided in the sub-controller 11, and this is detected as shown in FIG. By adding the command value L4 to the command value L4 from the power supply circuit 29 to the main power supply circuit 27, the voltage drop of the power cable 17 can be compensated. In the main control circuit 29, the extension cable 17A is controlled by the compensation circuit 29B.
Is also compensated. Thereby, welding can be performed with a stable welding voltage, and welding quality is improved.

Further, when the torch 13 moves during the welding operation and the degree of twisting of the wire feed cable 22 changes, the frictional resistance between the wire feed cable 22 and the wire W changes. In particular, as in the present embodiment,
When the cables between the torch 13 and the wire supply device 18 are lengthened to improve the mobility of the torch 13, the twist of the wire feed cable 22 changes greatly. For this reason, the feeding resistance of the wire W applied to each of the motors 24 and 33 greatly varies. However, as shown in FIG. 4, the rotation speed of the main motor
Is fed back to the main motor drive circuit 28 provided in the main motor 24, and when the rotational speed is about to decrease, a voltage corrected for the decrease is applied to the main motor 24 to compensate for the lack of torque. On the other hand, with respect to the sub motor 33, the corrected voltage command value S5 of the main motor drive circuit 28 is drawn into the sub motor drive circuit 38 provided in the sub controller 11, and a voltage based on this is applied to the sub motor 33. As a result, the voltage applied to the sub motor 33 changes in conjunction with the voltage applied to the main motor 24 in an offset state, and the sub motor 33 rotates in conjunction with the main motor 24.
That is, when the output torque of the main motor 24 increases, the output torque of the sub motor 33 also increases. As described above, since the sub motor 33 is linked to the main motor 24 that is feedback-controlled to stabilize the rotation speed, the two motors cooperate to share the load, and the wire feed speed according to the set value is achieved. The wire W can be supplied stably. Moreover, in the present embodiment, since the current value of the sub motor 33 is fed back in the sub motor drive circuit 38, the insufficient torque can be corrected more reliably than when the rotation speed of the sub motor 33 is controlled only by the voltage,
Therefore, the sub motor 33 can be more accurately
Can be linked. In addition, by operating the offset adjuster 38E provided in the sub-controller 11, the operator desires, for example, a setting in which the sub-motor 33 feeds the wire W faster than the main motor 24, and vice versa. Can handle cases.

As described above, in the welding machine according to the present embodiment, the cables extending between the torch 13 and the wire supply device 18 can be lengthened to improve the mobility of the torch 13 and to provide high quality. Can be welded. That is, since the feed speed of the wire W is stabilized by interlocking the sub motor 33 and the main motor 24, the amount of melting of the wire W becomes constant, the shape of the bead becomes uniform, and the voltage drop of the power cable 17 , The welding voltage becomes stable, and the penetration of the bead is good. In addition, the sub controller 11 is connected to the existing welding power source 12 and torch 13
As described above, the voltage drop compensation and the interlocking of the two submotors 33 and 24 can be made possible simply by additionally connecting them, etc., so that there is no cost for changing the equipment.

<Second Embodiment> This embodiment is shown in FIG. 7, and exemplifies a welding robot system to which the present invention is applied. Hereinafter, the same components as those of the first embodiment are denoted by the same reference numerals, and only different points will be described.

At the end of the arm of the robot 50, a torch 1
3 (the switch 36 of the first embodiment is not provided on the torch 13), and a wire supply device 18 is provided at a location remote from the robot 50, and the torch 13 and the wire supply device 18 are provided. Cables extend between the two. The welding power supply 12 is connected to the sub-controller 11, and the robot controller 52 is connected to the welding power supply 12 via the interface board 51. In the first embodiment, each circuit of the welding power supply 12 and the sub-controller 11 is driven by turning on the switch 36 provided at the tip of the torch 13, but in the present embodiment, the input is input to the robot 50. Based on the program, a start signal is input from the robot controller 52 to the welding power supply 12, and each circuit is driven.

Even with the configuration of this embodiment, the same effects as in the first embodiment can be obtained, and high quality welding can be performed. In particular, in the case of the robot 50, the same operation is automatically repeated, and the degree of twisting of the wire feeding cable is increased, so that the present invention of stably feeding the wire W is more effectively exerted.

<Other Embodiments> The present invention is not limited to the above embodiments. For example, the following embodiments are also included in the technical scope of the present invention.
In addition to the following, various changes can be made without departing from the scope of the invention. (1) In the above embodiment, the sub-controller 11 is provided with the voltage drop compensation circuit 30 and the sub-motor drive circuit 38. However, one or both of them may be built in the welding power source or the robot controller. (2) In the above embodiment, the sub motor drive circuit 3
Although the feedback of the current value is performed in 8, the configuration may be such that the feedback of the current value is not performed. (3) Furthermore, the present invention can be applied to any welding system other than the above-mentioned MIG system (for example, to a welding machine or a welding system such as a MAG system or a TIG system) as long as the system is a welding system for supplying a wire. .

[Brief description of the drawings]

FIG. 1 is a wiring diagram of a welding power source according to a first embodiment of the present invention.

FIG. 2 is a perspective view of a welding torch.

FIG. 3 is a side view of the wire supply device.

FIG. 4 is a block diagram of a main motor drive circuit and a sub motor drive circuit.

FIG. 5 is a graph showing a proportional relationship between a wire feed speed and a motor voltage.

FIG. 6 is a block diagram of a main control circuit, a main power supply circuit, and a voltage drop compensation circuit.

FIG. 7 is a wiring diagram of a welding system according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Welding machine 11 ... Welding sub-controller 12 ... Welding power supply 13 ... Torch 17 ... Power cable 24 ... Main motor 30 ... Voltage drop compensation circuit 31, 32 ... Potential detection line (potential detection part) 33 ... Sub motor 38 ... Sub motor drive Circuit 38E: Offset adjuster (adjustment means) 50: Robot

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-54-112755 (JP, A) JP-A-55-22453 (JP, A) JP-A-52-21236 (JP, A) JP-A-58-188565 (JP, A) Registered Utility Model 3048233 (JP, U) JP-B-54-26991 (JP, B2) JP-B-57-33099 (JP, B2) (58) ) Field surveyed (Int.Cl. ⁷ , DB name) B23K 9/12 B23K 9/10

Claims (4)

(57) [Claims] 1. A main motor capable of feeding a wire serving as a melting material toward an arc welding torch, and a sub motor provided integrally with the torch and capable of drawing the wire into the torch in cooperation with each other. A rotation speed of the main motor is fed back, the speed is compared with a set speed, and the main motor is set based on a voltage command value to make the speed equal to the set speed. In the speed control, the sub motor has a drive power corresponding to the voltage command value applied to the main motor, the drive power being offset from the drive power supplied to the main motor, and a rotational speed feedback control. Characterized in that it is supplied without performing welding, and is provided with means for adjusting the offset amount. controller. 2. A main motor capable of feeding a wire serving as a melting material to a torch for arc welding, a submotor provided integrally with the torch and capable of drawing the wire into the torch; A welding power supply that supplies electric power for arc generation to the main motor and supplies driving power to the main motor, wherein the main motor is fed back with its rotation speed, and compares this with a set speed. The motor is configured to be controlled at a constant speed based on a voltage command value that causes the rotation speed to reach the set speed, and is a driving power according to the voltage command value provided to the main motor to the sub motor. The drive power offset from the drive power supplied to the main motor is
A welding machine comprising: a sub motor control unit that operates so as to be supplied without performing rotation speed feedback control; and an offset amount adjustment unit. 3. The welding machine according to claim 2, wherein a power cable for transmitting electric power for arc generation is extended between the welding power source and the torch in a state insulated from the wire. A tip of the power cable and a tip of the wire are short-circuited in the torch, a voltage drop between both ends of the power cable is detected, and the voltage drop is determined based on the detection result. The voltage drop compensating means is provided with a pair of potential detecting sections, and the voltage compensating means is configured by connecting one of the potential detecting sections to a base end of the power cable. Detecting the potential of the base end of the power cable, and connecting the other potential detection unit to the base end of the wire short-circuited to the end of the power cable. The welder said wire voltage drop as compared to the power cable by utilizing equal to nothing, characterized in that it detects the leading end of the potential of the power cable. 4. A torch for arc welding, in which a wire serving as a melting material can be drawn by integrally providing a sub motor, is attached to a tip of a robot, and a main motor for feeding the wire toward the torch is provided. In order to arrange the main motor away from the robot and to cooperate the sub motor and the main motor, the rotation speed of the main motor is fed back and compared with a set speed. Is controlled so as to be controlled at a constant speed based on a voltage command value that causes the sub-motor to be supplied to the main motor with drive power according to the voltage command value given to the main motor. as the driving power offset from the drive power that is <br/> supplied without the rotational speed feedback control Welding system, characterized by comprising a sub motor control means for work, and a means for adjusting the offset amount.