JPH08309536A - Welding wire feeder - Google Patents

Abstract

PURPOSE: To execute unmanned and lessened manpower welding by detecting the elongation and contraction state of an elongator/contractor for elongating and contracting a guide route for a wire. CONSTITUTION: Hoist wire TIG welding is executed by a TIG arc power source 4, a wire heating power source 12, a TIG welding torch, a wire torch 9, the elongator/contractor 21 which is arranged between the end of a conduit 8 for guiding the wire 6 and the wire torch 9, etc. The elongation and contraction state of the elongator/contractor 21 is detected by an elongation and contraction state detecting means 32. A controller 31 is composed of a wire current control circuit 33 which sends the signal to increase and decrease wire heating current to the wire heating power source 12 by receiving the signal from the elongation and contraction state detecting circuit 32 for detecting the elongation and contraction state and a wire speed control circuit 34 for controlling the wire feed speed by receiving the signal from a photointerrupter of the elongator/contractor 21. As a result, the need for an operator for constant monitor for the purpose of regulating the heating electric power during welding is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding wire feeder, and more particularly to a cold or hot wire feeder for TIG welding and a wire feeder for GMA (gas shield metal arc) welding.

[0002]

2. Description of the Related Art FIG. 4 shows the construction of a welding apparatus which has been conventionally generally used as a hot wire TIG welding method.

An arc power source 4 for direct current welding is connected to the tungsten electrode 2 and the base material 3 in the TIG welding torch 1, and an arc 5 is formed in the argon shield gas with the tungsten electrode 2 as a negative electrode. The additive wire 6 for welding is guided from the wire feeding device 7 through the conduit 8 and the wire torch 9 connected thereto to the arc forming portion and brought into contact with the base material 3. Wire torch 9 is TIG welding torch 1
And the connecting member 10 mechanically couples and moves integrally.

A wire heating power source 12 is connected between the contact tip 11 arranged at the tip of the wire torch 9 and the base material 3, and a direct current or an alternating current is applied to the wire 6 to cause Joule heat generation, whereby the melting speed of the wire 6 is increased. Is increasing. The cold wire T that does not heat the wire 6
In the case of IG welding, the wire heating power source 12 is omitted in FIG.

In this hot wire TIG welding, it is necessary to adjust the heating power in accordance with the wire feeding speed. When the heating power is insufficient, the wire 6 is pushed out of the molten pool or hits the base metal 3. The wire torch 9 and the TIG welding torch 1 connected to the wire torch 9 are lifted up, and as a result, the arc length becomes very long, so that the welding cannot be continued. On the contrary, when the heating power is excessively large, the wire 6 is frequently heated and melted to generate spatter and adhere to the tungsten electrode 2, or the tip of the wire 6 and the tungsten electrode 2 are melted.
An arc is formed between and, which makes the welding state unstable.

Therefore, normally, the wire 6 is in a proper molten state,
That is, the operator manually adjusts the heating current while monitoring the welded portion so that the tip of the wire is in the state of being melted or immediately before being melted and is always in contact with the base material 3. Adjusting heating power.

Regarding the adjustment of heating power, the inventors of the present invention, as described in Japanese Patent Publication No. 5-75512, detect the occurrence of fusing from the wire voltage, and when the fusing occurs, lower the wire heating power to some extent. By gradually increasing the heating power from then to generate melting again,
We proposed a control method that automatically keeps the wire heating power close to the proper melting state.

It is preferable that the occurrence of fusing is as small as possible. However, in this method, fusing is required to occur at a frequency of about once every 2-3 seconds, and some spatter is unavoidable.

On the other hand, a device described in Japanese Patent Publication No. 56-34386 is known as a device for expanding and contracting the feeding path of the additive wire from the motor to the tip by TIG welding during welding. This technique is intended to automatically reciprocate the tip of the wire fed into the molten pool to intermittently melt the wire.

This device will be described with reference to FIG. In the figure, the addition wire 6 is fed from a wire reel (not shown), and is fed by rollers 13 and 13 'which are driven at a constant speed by a feeding motor, a conduit 14 placed in a deflected state, and a TIG welding torch. Through the wire guide tip 15 fixedly provided as a part of 1.
The molten pool 16 at the arc generation part is reached.

An external device (not shown) is used for the conduit 14
A force is applied to the end 17 of the conduit against the spring 18 to cause the conduit end 17 to reciprocate in the direction of arrow 19, resulting in a change in the deflection of conduit 14 as indicated by phantom line 14 ',
Thus, the feeding motor feeds the addition wire 6 in the forward direction at a constant speed, while the addition wire tip 20 reciprocates with respect to the molten pool 16.

The device including the spring 18 for changing the wire guide path is installed for the purpose of positively moving the wire tip 20 in and out of the arc 5 generation region and the molten pool 16, that is, for actively expanding and contracting. .

On the other hand, in GMA welding of mild steel, etc.,
Copper plated wires are usually used from the viewpoint of rust prevention and electrical conductivity. However, while this wire is unwound from the wire reel and reaches the tip of the torch, the copper plating is rubbed and peeled off, and the plating scraps are often accumulated in the torch, especially in the tip hole, often causing chip clogging, and the movement of the wire 6 And the arc burns back to make welding impossible, resulting in poor welding in the product.

Unlike the case where the life of the tip is worn,
Since this chip clogging occurs irregularly, it is difficult to predict. In the case of a GMA welding robot incorporated in a production line, there is a problem that the line must be stopped for chip replacement.

[0015]

The prior art of the above-mentioned TIG welding is, in order to prevent the torch from being lifted by the wire tension and to prevent the spatter from being generated due to overheat cutting,
The welding worker had to adjust the wire feeding speed and the heating current while monitoring the melting state of the wire.

Further, although an automatic control method utilizing the fusing condition has been developed, in that case, there is a problem that spatter occurs at a considerable frequency, and since spatter is accumulated on the tungsten electrode, it takes a long time. There was a drawback that continuous operation was difficult.

Further, in the conventional GMA welding, there is no suitable means for detecting the progress of tip clogging and preventing the wire feeding stop due to tip clogging.

An object of the present invention is to perform welding in which the wire heating current and the wire feeding speed can be automatically adjusted so as to reduce the frequency of spatters in TIG welding and maintain an appropriate wire melting state. It is to provide a wire feeding device.

Another object of the present invention is to provide a welding wire feeder having a tip clogging progress detector, which is capable of exchanging tips before tip clogging occurs in GMA welding.

[0020]

In order to achieve the above object, the present invention provides an expander for expanding and contracting a wire guide path between a conduit for guiding a wire to a torch and the torch. An expansion / contraction state detecting means for detecting the expansion / contraction state of is provided.

[0021]

According to the present invention, as described above, the expander is provided between the conduit and the torch, and the reaction force of the force received by the wire from the expander to the base material is sent from the expander. Since the soft flexible conduit on the feed motor side receives it, the expander connected to the end of this conduit expands and contracts like a spring scale by receiving a force corresponding to this reaction force. From the opposite viewpoint, the force generated in the expander is applied from the torch side end to the wire tip side.

In TIG welding, when the wire is not melted and the hard wire hits the base material, a strong pressing force is generated. In case of proper wire melting,
Since the wire is softened, the reaction force of the pressing force does not occur even if it makes contact. Therefore, if the reaction force from the base material can be detected, the wire feeding speed, the wire heating power, the wire insertion position, etc. can be changed to appropriately control the wire heating state.

When the expander is placed at the end of the torch, the force that the wire receives from the outside from there to the base material is mainly the frictional force that is received when passing through the tip that guides the energized wire. It consists of the reaction force that the tip of the wire contacts the base material and receives from the base material. When the wire is not in contact with the base material, the friction force is mainly when passing through the tip.

This frictional force is not so large as to cause a problem in general, but becomes large when plating dust is gradually accumulated in the tip hole of the copper-plated wire or the like and the wire is clogged.

Therefore, whether or not the wire is in contact with the base material is electrically detected, and the amount of expansion and contraction of the expander when the wire is in contact with the amount of expansion and contraction of the expander when not in contact
The force with which the wire is pressed against the base material and the progress of chip clogging can be detected, which can be useful for controlling the molten state of the wire and detecting chip clogging in advance.

[0026]

【Example】

(First Embodiment) FIG. 1 is a schematic configuration diagram of a TIG welding apparatus according to the first embodiment. TIG arc power source 4, wire heating power source 12, TIG welding torch 1, wire torch 9 connected to it, wire torch 9 disposed at a position distant from wire torch 9, and wire feeding push motor 36 and wire torch 9. The hot wire TIG welding is performed by the expander 21 which is disposed between the torch side end of the conduit 8 that guides the wire 6 to the side and expands and contracts the guide path of the wire 6.

In this embodiment, there is no wire feeding motor on the wire torch 9 side, and the wire feeding is of a simple push type.

In the figure, 31 is a controller, 32 is an expansion / contraction state detection circuit, 33 is a wire current control circuit, 34 is a wire speed control circuit, and 35 is a wire separation detection circuit. The functions of these units will be described later. .

FIG. 2 illustrates the structure and principle of the expander 21 used in this embodiment. Reference numeral 22 denotes a linear shaft having one end fixed to the wire torch 9 and having a hole through which the wire 6 passes in the center, and the linear push 23 slides axially on the outer surface thereof. End 2 of linear shaft 22
4 and a bottom surface 25 of the linear push 23 opposite to the wire torch, a compression spring 26 is provided.
An outer cylinder 27 connected to the conduit 8 is provided on the outer surface of 3, and is fixedly connected to the linear push 23.

Further, there is a photointerrupter setting member 28 connected and fixed to the linear shaft 22 side on the outer side thereof,
The photo interrupter 29 is turned on when the end portion 30 of the outer cylinder is present immediately below the photo interrupter 29,
If it does not exist, it works to turn it off.

That is, the expander 21 is contracted by the action of the spring 26 when the external force is not applied, and the photo interrupter 29 is turned on. When the external force is applied and the photo interrupter 29 extends for a certain amount or more, the photo interrupter 29 is turned off. To work.

The controller 31 shown in FIG. 1 receives a signal from the photointerrupter 29 of the expander 21 and receives a signal from the expansion / contraction state detection circuit 32 for detecting the expansion / contraction state to supply the wire heating current to the wire heating power supply 12. It is composed of a wire current control circuit 33 for sending a signal to increase and decrease and a wire speed control circuit 34 for controlling the wire feeding speed.

When the wire is not being fed, the expander 21
The inner spring 26 is fully extended and the expander 21 is short. The compression spring 26 is selected so that the expander 61 is in a substantially intermediate stretched state during feeding while the wire 6 is not in contact with the base material 3, and the photo interrupter 29 is in a substantially intermediate stretched state. It is installed at a position where the output changes sometimes.

Next, the operation of this device will be described. T
When the IG arc 5 is generated and the wire 6 is fed to the molten pool, the controller 31 first supplies the wire heating current corresponding to the wire feeding speed from the wire heating power source 12. If the wire heating current is insufficient, the wire feeding speed becomes faster than the progress of wire melting, and therefore the wire tip hits the base material 3 and the spring 26 in the expander 21 is compressed to change the melting speed. It tries to extend the wire feeding path by the difference in feeding speed.

As a result, the expander 21 is extended and the photo interrupter 29 is turned off. The expansion / contraction state detection circuit 32 in the controller 31 receives the OFF signal and receives the wire current control circuit 3
3 is commanded to gradually increase the wire current. Then, the wire heating current gradually approaches the proper state.

On the contrary, when the wire heating current is too large, the wire feeding speed is insufficient, so that the wire feeding path is shortened by the force of the spring 26 in the expander 21 and the wire tip is moved. It tries to press against the base material 3. At this time, since the photo interrupter 29 is turned on, the expansion / contraction state detection circuit 32 receives the signal and instructs the wire current control circuit 33 to gradually reduce the wire heating current, and approaches the appropriate heating current.

In this way, the heating current corresponding to the wire speed is adjusted, and as a result, the spring 2 in the expander 21 is adjusted.
At 6, the tip of the wire 6 is kept pressed against the base material 3 with a constant force.

For the force to be pressed against the base material 3, the strength of the spring 26 and the set position of the photo interrupter 29 are selected.
A proper value can be obtained by adjusting.

In this way, if the friction force of the wire feeding path in the wire torch 9 increases due to the clogging of the tip while controlling with the force set by the expander 21, the wire current is increased accordingly. 6 functions so as to reduce the force received from the base material 3 side, so that the wire 6 is finally overheated and separated from the base material 3.

The controller 31 is provided with a wire separation detecting circuit 35 described in Japanese Patent Publication No. 5-75511, which is a proposal of the present inventors, and is used as an output terminal of the wire heating power source 12, that is, a wire. By detecting the voltage between the base material 3 and the base material 6, it is possible to easily detect whether the wire 6 is in contact with or separate from the base material 3. If the tip of the wire frequently separates from the base material 3 during wire feeding, it is determined that the wire clogging of the contact tip 11 has progressed, and for example, a CRT display, a buzzer, not shown, Inform the operator that the chip is clogged by a suitable notification means such as a chime,
Measures such as tip replacement and cleaning can be taken.

(Second Embodiment) Next, an embodiment in the case of a cold wire not energized by the wire will be described. Since the structure of the apparatus is almost similar to the case where the heating power source 12 in FIG. 1 is omitted, the structure diagram is omitted.

In the present embodiment, the wire feed speed is controlled by the output signal of the photo interrupter 29, so that the TIG torch 1 is not stretched by the wire 6.
That is, when the set wire feeding speed is higher than the wire melting speed by the arc 5, the expander 21 extends and the photointerrupter 29 is turned off. Therefore, the controller 31 receives the signal and gradually reduces the wire feeding speed. And approach the appropriate feeding speed.

When the wire feeding speed becomes slower than the melting speed, the photo interrupter 29 is turned on, and the wire feeding speed is gradually increased in response to the signal. In this way, the wire feeding rate can be automatically adjusted to the wire melting rate, and the wire 26 is kept pressed by the spring 26 in the expander 21 with a constant force.

When the wire speed is gradually increased, the wire speed is controlled so as not to become higher than the set wire speed. Therefore, when the wire feeding speed is lower than the wire melting speed due to the object to be welded, the TIG torch 1 is not stretched by the wire 6, and the set wire speed is maintained with the photo interrupter 29 turned on. There is.

Although the heating current was controlled in the first embodiment and the feeding speed was controlled in the second embodiment, in addition to this, as the wire tip position approaches the arc 5, the wire melting speed is increased due to the heat generated by the arc 5. Constant wire speed,
The same control can be performed by setting a constant wire heating current and changing the wire insertion position according to the signal of the photo interrupter 29. Further, as the arc length becomes longer or the arc current becomes higher, the wire melting rate becomes faster, and thus the control of the arc current or the arc length can be performed instead.

(Third Embodiment) In the expander 21 of FIG.
The case where the on-off control is performed by the number of photo interrupters has been described, but FIG. 3 shows an embodiment in the case of two photo interrupters.

Photo interrupter 29a on the side closer to the chip
Indicates a weak force state, and the far side photointerrupter 29b detects a stronger force state. When applied to hot wire TIG welding, the photointerrupter 29 in a weak force state is used.
The wire heating power is increased / decreased by the output signal of "a" to maintain the proper heating power, and the wire feeding speed is controlled by the signal of the photointerrupter 29b in the state of a strong force.

Therefore, even when the response of the heating power control is slow, the force of the wire 6 pushing the base material 3 becomes strong and the wire speed is slowed down before the TIG torch 1 is lifted.
It is possible to prevent a situation in which the G torch 1 is lifted and the welding operation is interrupted.

In order to detect such an expansion / contraction state, it is possible to increase the number of digital type detectors or attach analog type detectors, and by doing so, finer control can be performed.

(Fourth Embodiment) A stretcher 21 having one photointerrupter shown in FIG. 2 is attached between the tip of the conduit and the GMA welding torch in the push type wire feeder. Normally, when the expander 21 contracts and the photointerrupter 29 is turned on, or when the chip clogging occurs during welding and it becomes necessary to increase the force for passing the chip, the expander 21 expands. Then, the spring 26 was set so that the photo interrupter 29 was turned off.

By doing so, the situation where the chip clogging is progressing can be detected from the output signal of the expander 21 and the chips can be replaced at the end of the welding, and the welding is interrupted due to the chip clogging or the defective product is generated. Can be prevented.

[0052]

According to the present invention, in TIG welding,
Since the proper heating power of the wire can be automatically maintained in the state where the spatter generation is extremely small, it is not necessary for the worker to constantly monitor the heating power during welding, which makes unmanned and labor-saving welding possible. It will be possible.

When the present invention is applied to semi-automatic TIG welding, there is no possibility that the wire hits the base metal and pulls the torch away from the base metal to make welding impossible.
Welding becomes easy. That is, in normal semi-automatic TIG welding, there is also a meaning to reduce the wire tension caused by the difficulty of adjusting the wire feeding speed as much as possible. Have been sent.

Therefore, the arc length becomes a little longer,
If the length is shortened, the position where the tip of the wire contacts the base metal will be greatly displaced, and it will come off the molten pool, making welding difficult.
Semi-automatic welding has not been put to practical use.

On the other hand, Japanese Unexamined Patent Publication No.
As described in Japanese Patent No. 297574, a method of inserting a wire from the inside of a shield gas nozzle along a tungsten electrode substantially in parallel is used in robot welding, but in semi-automatic TIG welding, the arc length is unstable. However, the wire melting rate is likely to change, and the wire more easily hits the base material, making it easier to lift the torch.

However, since the wire tension is eliminated by the present invention, the wire can be fed from the inside of the shield gas nozzle, and semi-automatic TIG welding can be performed with a smaller torch.

Further, especially in GMA welding, since the chips can be replaced at an appropriate time before the chips are clogged, the chips will not be clogged during welding and defective products will not be produced. Therefore, in the robot welding line or the like. It has various advantages such as continuous unmanned operation.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a hot wire TIG welding apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of an expander used in the hot wire TIG welding apparatus.

FIG. 3 is a sectional view of an expander according to another embodiment.

FIG. 4 is a schematic configuration diagram of a conventional hot wire TIG welding apparatus.

FIG. 5 is a configuration diagram showing an example of a conventional expansion / contraction device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 TIG torch 2 Tungsten electrode 3 Base material 4 Arc power supply 5 Arc 6 Wire 7 Wire feeder 8 Conduit 9 Wire torch 11 Contact tip 12 Wire heating power supply 21 Expander 26 Compression spring 29 Photointerrupter 31 Controller 32 Expansion state detection circuit 33 Wire current control circuit 34 Wire speed control circuit 35 Wire separation detection circuit 36 Push motor

Claims (5)

[Claims] 1. An expander / contractor for expanding / contracting a wire guide path is disposed between a conduit for guiding the wire to the torch and the torch, and an expandable / contracting state detecting means for detecting the expandable / compressed state of the expander / compressor is provided. Characteristic welding wire feeder. 2. The method according to claim 1, wherein at least one of a wire heating current, a wire feeding speed, a wire insertion position, an arc current, and an arc length is based on a detection signal from the expansion / contraction state detecting means. And a wire feeding device for welding. 3. The wire according to claim 1, wherein the wire heating current or the wire feeding speed is adjusted based on the detection signal from the expansion / contraction state detecting means so that the wire always contacts the base material with a constant force. A wire feeder for welding, characterized in that it comprises a feedback control means that operates as described above. 4. The wire contact detection means according to claim 2 or 3, wherein the wire contact detection means detects whether the wire is in contact with or separated from the base material, and the expansion and contraction when the wire is in contact with the base material. At least one of the wire heating current, the wire feeding speed, and the wire insertion position is adjusted so that the expansion / contraction amount of the container approaches the expansion / contraction amount of the expander when the wire is separated from the base material. A wire feeding device for welding, characterized in that: 5. The welding wire feeding device according to claim 1, further comprising a notifying unit for notifying occurrence of chip clogging based on a detection signal from the expansion / contraction state detecting unit.