JPH07246470A - Wire feeder for welding - Google Patents

Abstract

PURPOSE:To provide a wire feeder of push-pull or push system hard to generate the buckling of a wire and capable of stably feeding the wire at constant speed. CONSTITUTION:A welding torch 2, a pull roller 6 and a pull motor 8 are mounted on the tip arm 11 of an articulated welding robot 10, and an expansion member 21 is mounted on the wire introducing side of the pull roller 6. Meanwhile, a push roller 5 and a push motor 7 are mounted on the intermediate arm 12 of the robot 10. Moreover, a stand 13 is erected in the neighborhood of the robot 10, and a wire reel 1 is mounted on the stand. The wire 4 drawn out of the wire reel is introduced to the push roller by a conduit tube 14, and the wire 4 drawn out of the push roller is introduced to the expansion member by a conduit tube 3. The expansion member absorbs the expansion/contraction of a wire feed route generated due to the oscillation of the welding torch, and prevents an excessive tensile or compressive force from being applied to the wire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wire feeding device for feeding a welding wire such as a consumable electrode or a filler material to a welding portion, and more particularly to a wire feeding device at a constant speed and for preventing bending. Regarding means.

[0002]

2. Description of the Related Art FIG. 6 shows a conventionally known push-pull type wire feeder. In this figure, 1
Is a wire reel, 2 is a welding torch, 3 is a wire reel 1
The conduit tube 5 that guides the wire 4 pulled out from the welding torch 2 to the welding torch 2 is a push roller that pulls the wire 4 out of the wire reel 1 and pushes it into the conduit tube 3. 6 is the welding torch 2 side of the wire 4 that is pulled out from the conduit tube 3. The reference numeral 7 designates a pull roller for pulling in, the reference numeral 7 designates a push motor for rotationally driving the push roller 5, the reference numeral 8 designates a pull motor for rotationally driving the pull roller 6, and the reference numeral 9 designates a motor control circuit for controlling the rotation of the respective motors 7, 8. The push motor 7 is controlled at a constant speed by the motor control circuit 9 during the welding period and continuously feeds a constant amount of the wire 4 to the welded portion. On the other hand, the pull motor 8 is subjected to constant torque control by the motor control circuit 9, and always applies a constant tension to the wire 4.

The push-pull type wire feeder constructed as described above has a softer material such as aluminum than the push-type wire feeder which includes only the push roller 5 and does not include the pull roller 6. When the wire 4 is used, or when the wire 4 having a small diameter is used, or when the conduit tube 3 having a long length of 10 m is used, the wire 4 does not buckle. Supply stability is improved and welding efficiency can be improved.

By the way, in the MAG semi-automatic welding apparatus in which the pull roller 6 and the pull motor 8 are integrally incorporated in the welding torch 2, when the welding torch 2 is swung, the curved state of the conduit tube 3 changes accordingly, and the conduit tube 3 changes. Since the feeding path of the wire 4 in 3 changes, the feeding speed of the wire fed from the welding torch 2 also changes even when the push roller 5 feeds the wire 4 at a constant speed. Therefore, when the speed of the wire 4 fed from the tip of the welding torch 2 suddenly decreases, the arc burns back and damages the current-carrying tip (not shown) in the torch. On the other hand, when the wire speed suddenly increases, the wire 4 comes into contact with the base material and short-circuits, and a large amount of spatter is likely to occur when re-ignition by fusing.

In order to eliminate such inconvenience, the inventors of the present invention previously applied the pull roller 6 and the pull motor 8 as shown in FIG. 7 when applying the push-pull type wire feeder to a welding robot. The welding torch 2 incorporated in the above is mounted on the tip arm 11 of the articulated welding robot 10, the push roller 5 and the push motor 7 are mounted on the intermediate arm 12, and the length of the conduit tube 3 is set to 2 mm.
While limiting to m or less, by the motor control circuit 9,
A device for controlling the pull motor 8 at a constant speed and controlling the speed of the push motor 7 so that the load current of the pull motor 8 is constant has been proposed (JP-A-5-57440). In addition,
In FIG. 5, reference numeral 13 is a stand for holding the wire reel 1, reference numeral 14 is a conduit tube for guiding the wire 4 from the wire reel 1 to the push roller 5, and reference numeral 1
Reference numeral 5 denotes a spring member that holds the conduit tube 14.

In the wire feeding device previously proposed by the inventors of the present application, the pull motor 8 is controlled at a constant speed, and the push motor 7 is speed controlled so that the load current of the pull motor 8 becomes constant. In the welding robot in which the feeding speed is stable and the operation speed of the tip arm 11 with respect to the intermediate arm 12 is relatively slow, the above-mentioned conventional inconvenience can be solved. Further, since the length of the conduit tube 3 is limited to 2 m or less by devising the setting positions of the push roller 5 and the push motor 7, the pull motor 8
The load on the pull motor 8 is reduced, and the pull motor 8 can be downsized.

[0007]

However, in a welding robot for a special purpose, which requires the tip arm 11 to be bent sharply and at a large angle with respect to the intermediate arm 12, the tip arm 11 violently moves as the tip arm 11 moves. It was difficult to control the speed of the push motor 7 so that the feeding speed of the wire 4 was constant according to the bent conduit tube 3, and it was practically difficult to stabilize the feeding speed of the wire 4. . That is, when the relatively short conduit tube 3 having a length of 2 m or less is bent along with the operation of the tip arm 11, the wire feeding path changes within ± 10 mm, but the torque of the pull motor 8 changes as the wire feeding path changes. Rapidly changes, and the speed of the push motor 7 also rapidly and largely changes, so that an excessive response is often generated. As a result, in the case where the push motor 7 hunting the small and small capacity pull motor 8 cannot be fed at a constant speed, or when a soft wire such as aluminum is fed, the push motor 7
Wire 4 buckles halfway because it is pushed out by
It becomes easy to cause inconvenience that it becomes impossible to send.

The present invention has been made in order to solve the disadvantages of the prior art, and its object is, firstly, even if the conduit tube length between the push motor and the pull motor is short. It is an object of the present invention to provide a push-pull type wire feeder capable of immediately feeding a wire at a constant speed in response to the sudden bending of the wire. Secondly, it is to provide a push-type wire feeding device in which buckling of the wire hardly occurs and the wire can be fed stably at a constant speed.

[0009]

In order to solve the first problem, the present invention provides a welding wire feeder having both a push roller and a pull roller in a wire feeding path, and An elastic member that expands and contracts according to the expansion and contraction of the wire feeding path is provided between the pull roller and the pull roller. In this case, in order to always maintain the effect of the elastic member, the elastic state detector that detects the elastic state of the elastic member and the rotation control of the push roller and / or the pull roller according to the output signal from the elastic state detector. And a motor control circuit for constantly maintaining the expansion / contraction member in the reference state.

In order to solve the second problem, in a welding wire feeder having only a push roller in the wire feeding path and no pull roller, the wire feeding device is provided downstream of the push roller. An elastic member that expands and contracts according to the expansion and contraction of the supply path is provided. Even in this case, in order to always maintain the effect of the expansion / contraction member, the expansion / contraction state detector for detecting the expansion / contraction state of the expansion / contraction member and the rotation control of the push roller according to the output signal from the expansion / contraction state detector are performed. It is particularly preferable that the motor control circuit keeps the member in the standard state at all times.

[0011]

When a telescopic member that expands and contracts according to the expansion and contraction of the wire feeding path is arranged in the predetermined wire feeding path, for example, the tip arm of the robot equipped with the welding torch suddenly moves and the wire inside the conduit tube is moved. Even if the wire feed path suddenly becomes longer and the wire is about to be pulled, the elastic member expands according to the tensile force acting on the conduit tube, and the wire feed path becomes longer, so a strong pulling force is applied to the pull motor. There is no action, and constant-speed feeding of the wire can be maintained. On the contrary, even if the wire feeding path in the conduit tube is suddenly shortened and a force in the compression direction is applied to the wire, the expandable member contracts according to the compression force, and the wire path is shortened. Excessive compression force does not act,
Buckling of the wire is prevented.

Further, in this device, an expansion / contraction state detector for detecting the expansion / contraction state of the expansion / contraction member, and rotation control of a push roller or the like according to an output signal from the expansion / contraction state detector,
If a motor control circuit that keeps the telescopic member always in the standard state is provided, when the wire feed path is about to extend beyond the allowable range of the telescopic member, or the wire feed path shrinks beyond the allowable range of the telescopic member. Even when that happens, the expansion / contraction state detectors such as limit switches detect that,
Since the elastic member can be returned to the standard state by controlling the wire feeding speed, an excessive force does not act on the wire, the push motor, etc., and the wire can be fed at constant speed and buckling prevention can be maintained.

[0013]

【Example】

<First Embodiment> A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a configuration diagram of an articulated welding robot equipped with a wire feeding device according to this example, FIG. 2 is a cross-sectional view of a telescopic device and its peripheral devices, and FIG. 3 is a circuit diagram showing a configuration of a motor control circuit.

In FIG. 1, reference numeral 21 indicates an elastic member, and the other portions corresponding to those in FIG. 7 have the same reference numerals. As is clear from this figure, the wire feeding device of this example is the articulated welding robot 10
An elastic member 21 that expands and contracts in accordance with the expansion and contraction of the wire feeding path is provided in the wire introducing portion of the pull roller 6 attached to the tip arm 11 together with the welding torch 2.

As shown in FIG. 2, the elastic member 21 has an outer cylinder 23 having a linear shaft 22 formed in the center thereof, a slider 24 slidably mounted in the outer cylinder 23, and the slider 24. 25 for regulating the stop end of the slider and a spring member 26 for constantly urging the slider 24 toward the stopper 25.
And limit switches 27, 28, 29 which are expansion / contraction state detectors set in the outer cylinder 23.

A male screw 31 for connecting to a pull roller device 30 in which the pull roller 6 and the pull motor 8 are integrally incorporated is projectingly provided at one end of the outer cylinder 23, and a stopper 25 is provided at the other end of the outer cylinder 23. Male screw 32 for attaching
Is engraved. Further, the outer cylinder 23 is provided with a small-diameter wire insertion hole 33 penetrating from the central portion of the tip of the linear shaft 22 to the central portion of the tip of the male screw 31. The pull roller device 30 has a screw hole 3 at a predetermined position.
4 is opened, and the outer cylinder 23 has the male screw 31
Is screwed into the screw hole 34 to be integrated with the pull roller device 30, and the axis of the wire insertion hole 33 is matched with the wire insertion portion of the pull roller 6.

The slider 24 is the linear shaft 22.
Is formed into a cylindrical shape having a through hole 35 into which a conduit tube can be inserted, and an internal thread 37 for attaching a connecting member 36 of a conduit tube is engraved on the inner surface of one end thereof, and a stopper 25 is formed on a part of the peripheral surface. A protrusion 38 for engaging is formed. A male thread 39 for screwing into the female thread 37 is engraved on the outer surface of one end of the connector 36 of the conduit tube, and a mounting portion 40 of the conduit tube 3 is formed to project at the other end. Further, the connector 36 has a small-diameter wire insertion hole 41 penetrating from the central portion of the tip of the male screw 39 to the central portion of the mounting portion 40. A conduit tube connector 36 is attached to the slider 24 by screwing a male screw 39 into a female screw 37. The wire 4 fed through the conduit tube 3 has a wire insertion hole 40, a through hole 35, and a wire insertion hole 3
It reaches the pull roller 6 through 3 and is introduced into the welding torch 2 (not shown) by the pull roller 6.

The stopper 25 has a through hole 42 through which one end of the slider 24 can be inserted and a projection 38 formed on the peripheral surface of the slider 24 can be engaged.
5a and a peripheral wall 25b that is erected from the periphery of the surface portion 25a and has an inner surface on which a female screw 43 for engaging with the male screw 32 engraved on the outer cylinder 23 is engraved. Has been formed. The stopper 25 is formed by screwing a male screw 32 and a female screw 43 into the outer cylinder 23.
The slider 24 is prevented from coming off on the inner surface of the surface portion 25a.

The spring member 26 corresponds to the linear shaft 22.
The slider 24 is constantly attached to the stopper 25 side by abutting one end against the inner surface of the outer cylinder 23 and the other end against the tip of the slider 24. The length and spring constant of the spring member 26 are appropriately set in consideration of the amount of change in the wire feeding path that occurs during wire feeding and the magnitude of the load torque of the pull motor 8 required to feed the wire 4 at a constant speed. To be selected.

The limit switches 27, 28, 29 are arranged on the movement path of the slider 24 on the inner surface of the outer cylinder 23, and one or a plurality of limit switches are selectively moved as the slider 24 moves. It is supposed to work on. That is, as shown in FIG. 2, the first limit switch 27 is set to a position where the first limit switch 27 is switched from the off state to the on state when the tip of the slider 24 reaches just before the spring member 26 is fully contracted. The limit switch 29 is set to a position where the ON state is switched to the OFF state when the tip of the slider 24 reaches just before the spring member 26 is fully extended. Further, the second limit switch 28 is set to the reference position of its intermediate portion.

Therefore, when the tip of the slider 24 is at the reference position, the second and third limit switches 28 and 29 are switched to the on state, and the first limit switch 27 is turned to the off state. From this state, the expansion / contraction member 21 contracts so that the tip end of the slider 24 has the spring member 26
When the first limit switch 27 is switched to the ON state immediately before the end of the contraction, all the limit switches 27, 28 and 29 are turned to the ON state. On the contrary, when the telescopic member 21 expands and the tip of the slider 24 deviates from the reference position, the second limit switch 28 is turned off and only the third limit switch 29 is turned on. The elastic member 21 further extends from this state,
When the tip of the slider 24 reaches just before the spring member 26 is fully extended, the third limit switch 29 is also switched to the off state, and all the limit switches 27, 28, 2 are turned on.
9 is turned off. Therefore, by detecting the ON / OFF state of the limit switch, it is possible to detect the expansion and contraction and expansion / contraction amount of the elastic member 21, that is, the expansion / contraction amount and expansion / contraction amount of the wire feeding path.

Next, the structure of the motor control circuit 9 will be described with reference to FIG.

As shown in FIG. 3, the motor control circuit 9 of the present embodiment has a proportional coefficient k adjusted according to the wire feed speed commander 51 and the ON / OFF states of the limit switches 27, 28 and 29. From the proportional coefficient adjusting circuit 52 for multiplying the wire feeding speed command signal a from the wire feeding speed commander 51, the speed detecting circuit 53 of the push motor 7, the speed detecting circuit 54 of the pull motor 8, and the proportional coefficient adjusting circuit 52. And a first comparator 55 for comparing the push motor speed command signal b from the push motor speed c from the speed detection circuit 53,
Pull motor speed command signal d from the proportional coefficient adjusting circuit 52
And a second comparator 56 that compares the pull motor speed e of the speed detection circuit 54 with the second comparator 56, and a control signal is generated based on the difference signal f from the first comparator 55 so that the difference signal f becomes zero. And a push motor drive circuit 57 for driving the push motor 7, and a control signal is generated based on the difference signal g from the second comparator 56, and the push motor 8 is driven so that the difference signal g becomes zero. And a pull motor drive circuit 58. As the speed detection circuit 53 of the push motor 7, one utilizing the back electromotive force of the push motor 7 is suitable, and as the speed detection circuit 54 of the pull motor 8, an encoder is particularly suitable.

The operation of the wire feeding apparatus of the present example constructed as described above will be described below.

In a stationary state, that is, the articulated welding robot 10
In a state in which the tip arm 11 of FIG. 1 does not swing with respect to the intermediate arm 12, the push motor 7 includes the proportional coefficient adjusting circuit 52, the speed detecting circuit 53, and the first comparator 55.
Feedback control is performed by the push motor drive circuit 57, and the wire 4 is accurately fed to the pull roller 6 side at a constant speed via the push roller 5. On the other hand, the pull motor 8 is feedback-controlled by the proportional coefficient adjusting circuit 52, the speed detecting circuit 54, the second comparator 56, and the pull motor driving circuit 58, and the wire 4 is accurately welded to the torch 2 via the pull roller 6. It is sent to the side at a constant speed. At this time, the motor control circuit 9 always positions the tip of the slider 24 in the vicinity of the reference position of the elastic member 21, so that the proportional coefficient adjusting circuit can be used when the second and third limit switches 28 and 29 are on. The proportional coefficient k set at 52 is increased at a rate of 0.5% per second to gradually increase the speed of the push motor 7, the third limit switch 29 is turned on, and the second limit switch 28 is turned on.
When is off, the proportional coefficient k set by the proportional coefficient adjusting circuit 52 is decreased at a rate of 0.5% per second, and the push motor 7 is gradually decelerated.

Tip arm 11 of articulated welding robot 10
Abruptly oscillates with respect to the intermediate arm 12, the conduit tube 3 bends in accordance with the extension of the feed path length of the wire 4 and a tensile force is applied to the wire 4 in the absence of the elastic member 21. In the wire feeding device of the present example including the elastic member 21, the elastic member 21 extends in accordance with the extension of the feeding path length of the wire 4, so that the bending of the conduit tube 3 is prevented or alleviated, and the wire 4 The increase of the tensile force acting on is suppressed. Therefore, the constant speed feeding property of the wire 4 can be maintained. On the contrary, the intermediate arm 1
When the tip arm 11 that was swinging with respect to 2 suddenly returns to the original position, if the telescopic member 21 does not exist, the wire 4
The conduit tube 3 bends in accordance with the contraction of the feeding path length of the wire, and a compressive force (buckling force) is applied to the wire 4. However, in the wire feeding device of this example including the elastic member 21, Since the expansion / contraction member 21 contracts according to the contraction of the feeding path length, the bending of the conduit tube 3 is prevented or alleviated, and the buckling force acting on the wire 4 is suppressed. Therefore, also in this case, the constant-speed feedability of the wire 4 can be maintained, and the buckling of the wire 4 can be prevented.

When the expansion / contraction member 21 is expanded and the third limit switch 29 is turned off, the motor control circuit 9 decreases the proportional coefficient k set by the proportional coefficient adjusting circuit 52 by 5% from the current value. The push motor 7 is decelerated. By doing so, the feeding path of the wire 4 is shortened and the tensile force acting on the wire 4 is slightly increased, so that the slider 24 is returned to the reference position side by the force. Therefore,
The excessive feeding of the wire 4 due to the abutment of the slider 24 and the stopper 25 is prevented, and the buckling of the wire 4 is prevented.
On the contrary, when the elastic member 21 contracts and the first limit switch 27 switches to the ON state, the motor control circuit 9
Increases the push motor 7 by increasing the proportional coefficient k set by the proportional coefficient adjusting circuit 52 by 5% from the current value. By doing so, the feeding path of the wire 4 becomes long and the compressive force acting on the wire 4 increases slightly, so that the slider 24 is returned to the reference position side by the force. Therefore, the excessive load of the pull motor 8 caused by the contraction of the spring member is prevented, and the constant speed feeding of the wire 4 is maintained.

In the wire feeding apparatus of this example, the telescopic member 21 which expands and contracts in accordance with the expansion and contraction of the wire feeding path is arranged immediately before the pull roller 6, so that the tip arm 11 of the robot 10 having the welding torch 2 mounted thereon. Even if the wire feed path in the conduit tube 3 suddenly lengthens or shortens, the expansion and contraction of the elastic member 21 absorbs the expansion and contraction of the wire feed path. Therefore, the bending of the conduit tube 3 is prevented or reduced, the constant speed feeding of the wire 4 is maintained, and the wire 4 is
Buckling is prevented.

Further, the wire feeding apparatus of the present embodiment, in addition to the expanding / contracting member 21, detects limit switches 27, 28, 29 for detecting the expansion / contraction state of the expanding / contracting member 21, and outputs signals from the limit switches. Since the rotation control of the push motor 7 is performed by the motor control circuit 9 that constantly maintains the expansion / contraction member 21 in the standard state, the wire feeding path is likely to expand or contract beyond the allowable range of the expansion / contraction member 21. At any time, the elastic member 21 can be returned to the reference state by these devices. Therefore, the reliability of the device can be further improved.

<Second Embodiment> A second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram of an articulated welding robot equipped with the wire feeding device according to the present embodiment, and the same reference numerals are displayed in the parts corresponding to those in FIG.

As shown in FIG. 4, the wire feeding device of this embodiment is characterized in that the elastic member 21 is provided near the exit side of the push roller 5. The same members as those provided in the wire feeding device of the first embodiment can be used as the respective members constituting the wire feeding device, but the bending of the conduit tube 3 due to the swing of the welding torch 2 is reduced. Therefore, it is particularly preferable that the conduit tube 3 be shorter and lighter than in the case of the first embodiment. The other structure is the same as that of the first embodiment, and the description thereof is omitted to avoid duplication.

The wire feeding device of this embodiment has the same effects as the wire feeding device according to the first embodiment, and the elastic member 21 is connected to the exit side of the push roller 5, that is, the intermediate arm of the articulated welding robot 10. Since it is mounted on the tip arm 12, the weight of the device mounted on the tip arm 11 can be reduced, and the operation of the tip arm 11 can be made lighter.

<Third Embodiment> A third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a configuration diagram of an articulated welding robot equipped with the wire feeding device according to the present example, and the same reference numerals are displayed in the portions corresponding to those in FIG. 1 described above.

As shown in FIG. 4, the wire feeding apparatus of the present embodiment omits the pull roller 6 and the pull motor 8 and feeds the wire 4 only by the push roller 5.
The elastic member 21 is provided near the exit side of the push roller 5. Of course, in this case, the motor control circuit 9 is configured to control only the push motor 7. The other parts are configured in the same manner as in the first embodiment, and therefore their description is omitted to avoid duplication.

In the wire feeding device of this example, the elastic member 21 is provided near the outlet side of the push roller 5, and the rotation speed of the push motor 7 is controlled according to the expansion and contraction of the elastic member 21. The bending of the conduit tube 3 due to the swing of the welding torch 2 is reduced, and the constant-speed feeding property and the buckling resistance of the wire 4 can be improved.

Other examples of the present invention will be listed below.

In each of the above-described embodiments, the elastic member 21.
In addition to the limit switch 2 as a telescopic state detector
7, 28, 29 and the motor control circuit 9 for controlling the rotation of the push roller in accordance with the output signal from the limit switch. However, when the expansion / contraction amount of the expansion / contraction member 21 is sufficiently large, the limit switch Also, the motor control circuit 9 can be omitted.

In each of the above-mentioned embodiments, the MAG welding using the articulated welding robot 10 has been described as an example. However, cold wire or hot wire is added T
Of course, it can also be applied to the feeding of the additive wire in IG welding.

In each of the above embodiments, the expansion / contraction member 21 is expanded / contracted by controlling only the push motor 7, but the expansion / contraction member 21 is also controlled by controlling both the push motor 7 and the pull motor 8. Expansion and contraction control can be performed.

Although the limit switches 27, 28, and 29 are used as the expansion / contraction state detectors in each of the above-described embodiments, other detectors such as a photo interrupter may be used instead.

[0041]

As described above, according to the present invention,
An expandable member that expands and contracts according to the expansion and contraction of the wire feeding path is arranged in the wire feeding path, so even if the welding torch suddenly moves and the wire feeding path length in the conduit tube fluctuates rapidly, it will expand and contract. Since the expansion and contraction of the member can absorb the expansion and contraction of the wire feeding path, the bending of the conduit tube can be prevented or reduced, and the constant speed feeding property and buckling resistance of the wire can be improved. In addition to the elastic member,
An expansion / contraction state detector for detecting the expansion / contraction state of the expansion / contraction member 21,
When a motor control circuit that controls the rotation of a push motor or the like according to the output signal from the expansion / contraction state detector and constantly maintains the expansion / contraction member in the standard state, the expansion / contraction amount of the wire feeding path is expanded / contracted. Even if it exceeds the allowable range of the member, it is possible to suppress the bending of the conduit tube,
The device can be made compact and highly reliable.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a welding robot equipped with a wire feeding device according to a first embodiment.

FIG. 2 is a cross-sectional view of an elastic member and its peripheral members.

FIG. 3 is a circuit diagram of a motor control circuit.

FIG. 4 is a configuration diagram of a welding robot equipped with a wire feeding device according to a second embodiment.

FIG. 5 is a configuration diagram of a welding robot equipped with a wire feeding device according to a third embodiment.

FIG. 6 is a configuration diagram of a wire feeding device according to a conventional example.

FIG. 7 is a configuration diagram of a welding robot equipped with a wire feeding device previously proposed by the present inventors.

[Explanation of symbols]

1 wire reel 2 welding torch 3 conduit tube 4 wire 5 push roller 6 pull roller 7 push motor 8 pull motor 9 motor control circuit 21 expansion / contraction member 23 outer cylinder 24 slider 25 stopper 26 spring member 27, 28, 29 limit switch (expansion / contraction state detector) ) 51 wire feed speed commander 52 proportional coefficient adjustment circuit 53 push motor speed detection circuit 54 pull motor speed detection circuit 55 first comparator 56 second comparator 57 push motor drive circuit 58 pull motor drive circuit

Claims (4)

[Claims] 1. A wire reel, a welding torch, a conduit tube for guiding the wire drawn from the wire reel to the welding torch, a push roller for pushing the wire drawn from the wire reel toward the welding torch, and a push roller. In a welding wire feeding device including a pull roller for pulling a pushed wire toward a welding torch side, an elastic member that expands and contracts according to expansion and contraction of a wire feeding path is provided between the push roller and the pull roller. A wire feeder for welding, which is characterized in that 2. The welding wire feeding device according to claim 1, wherein a stretchable state detector that detects a stretchable state of the stretchable member, and the push roller and the push roller according to an output signal from the stretchable state detector. And / or a motor control circuit for controlling the rotation of the pull roller and for always maintaining the elastic member in a standard state. 3. A welding reel comprising: a wire reel; a welding torch; a conduit tube for guiding the wire drawn from the wire reel to the welding torch; and a push roller for pushing the wire drawn from the wire reel toward the welding torch. In the wire feeding device, an expanding / contracting member that expands / contracts according to expansion / contraction of the wire feeding path is provided on the downstream side of the push roller. 4. The welding wire feeding device according to claim 3, wherein a stretchable state detector that detects a stretchable state of the stretchable member, and a push roller of the push roller according to an output signal from the stretchable state detector. A welding wire feeding device, comprising: a motor control circuit that controls rotation and maintains the elastic member in a standard state at all times.