JPH11123559A - Welding torch for high speed mig welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high speed MIG welding having restrained fluctuation of welding condition by bring a welding wire into contact with a contact tube or a feeding tip under stable condition. SOLUTION: In this welding torch, a pressing tool 20 is screwed into a pressing tool insertion hole of singular or plural number which is formed on a side wall of a feeding tip 8 or a contact tube and reaches to a wire feeding hole and elastic force of a spring 25 is transmitted to a pressurizing ball 23 through a spacer 26. A welding wire a is pressed against an inner surface of the wire feeding hole with the pressurizing ball 23 while the same is rolled to supply electric power to the welding wire a. As sliding friction between the pressurizing ball 23 and the welding wire a is restrained hereby, abrasion on the welding wire a is reduced, stable electric power supply is enabled and durability of the pressurizing ball 23 is improved herewith.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding torch suitable for high-speed MIG welding of a metal material such as aluminum while reliably supplying power to a welding wire running at a high speed.

[0002]

2. Description of the Related Art In MIG welding, a welding torch 1 is opposed to a base material A as shown in FIG. The welding wire a is fed from the spool 2 by a feed roller 4 driven by a motor 3, and is sent to a welding portion via a wire feed hole 6 of a contact tube 5. At this time, the welding wire a is connected to the welding power source 7 via the contact tube 5, and a voltage is applied between the welding wire a and the base material A. In addition.
A power supply tip 8 as shown in FIG. 2 may be used instead of the contact tube 5. Tip b of welding wire a
Is heated by an arc c generated between itself and the base material A by application of a voltage from the welding power source 7 to be dropped as molten droplets to form a molten pool d. The molten pool d is cooled as the welding proceeds, and becomes a weld bead e. In addition, an inert gas G such as Ar is blown toward the welding portion through an annular space between the welding nozzle 9 and the contact tube 5 to maintain the welding portion in a protective atmosphere.

The power supply tip 8 is screwed into a welding wire insertion tube 11 inserted into an outer tube 10 of the welding torch 1, as shown in FIG. When the welding wire a passes through the wire feed hole 6 of the feed tip 8, a point in contact with the inner wall surface of the wire feed hole 6 becomes the feed point P, and the welding power source 7 supplies the welding wire a.
Power is supplied to Power supply using the contact tube 5
This is done in much the same way. The wire feed hole 6 formed in the contact tube 5 or the power supply tip 8 is usually designed to have an inner diameter larger by 0.2 to 0.4 mm than the diameter of the welding wire a. Therefore, blurring occurs in the welding wire a, and not only the target position is not fixed, but also it is difficult to obtain the power supply point P. As a result, the arc c generated between the welding wire a and the base material A becomes unstable, and it becomes difficult to form a sound welding bead e.

In order to reliably bring the welding wire into contact with the power supply tip, a presser biased by a spring is provided on the power supply tip,
Pressing a welding wire against the inner wall surface of a wire feed hole provided in a power feeding tip is introduced in Japanese Patent Application Laid-Open No. 64-18582. However, the structure of the power supply tip becomes complicated, and the provision of the holding member tends to hinder smooth feeding of the welding wire. Further, metal powder, debris, and the like generated by the welding wire rubbing against the wire feeding hole and the inner wall surface of the holding member are liable to accumulate therein, which also hinders smooth feeding of the welding wire. . Regarding this point,
As disclosed in Japanese Patent Publication No. 182886, a method in which a welding wire is pressed against an inner wall surface of a wire feed hole by a pressurized ball urged by a spring is employed, compared with a case where a presser is used. The generation of powder, debris, etc. is small and the welding wire is fed smoothly.

[0005]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 61-1828
In the power supply chip introduced in Japanese Patent No. 86, as shown in FIG. 3, a through hole reaching the wire feed hole 6 is formed in the side wall, and a spherical or hemispherical pressure ball 12 and a spring 13 made of a hard material are formed. It is put in the through hole, and is covered with a cap 14 that supports one end of the spring 13. The spring 13
It is compressed between the pressing ball 12 and the cap 14, and a repulsive force as a reaction force is applied to the pressing ball 12. However, since the pressurized ball 12 is directly pressed by the spring 13, it cannot be rotated smoothly, and sliding friction occurs with the welding wire a. The sliding friction, together with the fact that the pressure ball 12 is a hard material, promotes wear of the welding wire a. As a result, abrasion powder is still likely to be generated, and the generated abrasion powder accumulates in the wire feeding hole 6 to hinder the smooth feeding of the welding wire a. In addition, since the pressing ball 12 is pressed by the spring 13, the pressure for pressing the welding wire a against the inner wall surface of the wire feed hole 6 is gradually reduced due to wear of the pressing ball 12, and the power supply efficiency may be reduced. There is. The present invention has been devised in order to solve such a problem, and it has been proposed that the contact between a welding ball and a pressurized ball housed in a contact tube or a power supply tip be changed from sliding friction to rolling friction, thereby achieving stable operation. An object of the present invention is to provide a welding torch which can supply a welding wire under a condition and can smoothly feed the welding wire, and has excellent durability.

[0006]

In order to achieve the object, a welding torch for high-speed MIG welding according to the present invention comprises: a contact tube or a power supply tip having an axially extending wire feed hole passing through a central portion thereof; One or more holding member insertion holes formed in the side wall of the contact tube or the power supply tip and reaching the wire feeding hole; a holding member having a bottomed cylindrical portion screwed into the holding member insertion hole; A spring having one end supported on the bottom wall of the cylindrical portion, a spacer supporting the other end of the spring, and a pressure ball which is in contact with the spacer and is prevented from being removed at the reduced diameter opening of the bottomed cylindrical portion. Wherein a welding wire passing through the wire feed hole is pressed against an inner peripheral surface of the wire feed hole by a repulsive force of the spring.

A female screw is engraved on the inner peripheral surface of the holding tool insertion hole,
By screwing a male screw engraved on the outer peripheral surface of the bottomed cylindrical portion with the female screw, the presser is detachably attached to the contact tube or the power supply tip. Further, the force for pressing the welding wire against the inner peripheral surface of the wire feed hole is adjusted by the amount of screwing of the holding tool into the contact tube or the power supply tip. When the nut is screwed into the presser, the presser is prevented from coming off from the contact tube or the power supply tip. The pressurized ball is preferably made of a hard insulating material such as ceramics in order to avoid inflow of current and generation of spark. When a plurality of pressers are mounted, they can be arranged on a straight line extending in the axial direction of the contact tube or the power supply tip. Alternatively, they may be arranged at different positions in the circumferential direction of the contact tube or the power supply tip.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the structure of FIG. 3 in which the pressing ball 12 is directly pressed by the spring 13, the end of the spring 13 is pressed against the pressing ball 12 as described above, so that the rotation of the pressing ball 12 is suppressed. Is done. As a result, the pressurized ball 12 and the welding wire a come into sliding contact with each other, and the welding wire feeding load increases due to the frictional force between the two. If the welding wire feeding load is excessively increased, the buckling of the welding wire a occurs, so that the pressing force of the pressure ball 12 must be reduced.
When welding at normal speed, even if the pressing force is small, welding bead failure due to power supply loss will not be a defect,
In high-speed welding at a welding speed of more than 2.5 m / min, even if power is lost for a short time, the amount of deposited metal per unit time is insufficient, so that welding defects are likely to occur. Further, the welding wire a and the pressurized ball 12 are severely worn, and the wire feed hole 6 is easily clogged. Therefore, in order to eliminate the sliding contact between the pressurized ball 12 and the welding wire a in high-speed welding, the pressurized ball 12
Must be guaranteed.

In the welding torch according to the present invention, FIG.
As shown in (b), one or a plurality of presser insertion holes 15 are formed in the side wall of the power supply chip 8. Holder insertion hole 15
Reaches the wire feed hole 6 extending in the axial direction from the center of the power supply chip 8, and an internal thread 16 (FIG. 5) is engraved on the inner surface thereof. In the example of FIG. 4, the three presser insertion holes 15, 15, 15 are arranged on a straight line extending in the axial direction of the power supply chip 8. It is also possible to slightly shift the positional relationship in the direction. That is, when the welding wire a is pressed against the inner peripheral surface of the wire feeding hole 6 from a plurality of directions, the uneven distribution of the welding wire a in the wire feeding hole 6 is reliably eliminated. As shown in FIG. 4B, the holding member 20 is screwed into the holding member insertion hole 15, and is prevented from being removed by the nut 17. Holder 20
Has a cylindrical portion 21 having a bottomed cylindrical shape as shown in FIG. 6, and a male screw (not shown) engraved on the outer peripheral surface of the cylindrical portion 21 is screwed into the female screw 16 of the holding tool insertion hole 15. By being combined, it is fixed to the power supply chip 8. By fastening the nut 17 to the fixed holding member 20, the holding member 20 is prevented from loosening or falling off due to a vibration generated at the time of feeding the welding wire a. It is also possible to fix the presser 20 to the power supply tip 8 with a bayonet joint instead of the retaining by the nut 17.

The cylindrical portion 21 is provided with a pressurized ball 2 housed therein.
The opening 2 whose tip is slightly reduced in diameter so that it does not fall off
I have two. A resilient force of a spring 25, one end of which is supported by the bottom wall 24 of the cylindrical portion 21, is applied to the pressure ball 23 via a spacer 26. By interposing a spacer 26 between the pressing ball 23 and the spring 25, unlike the method in which the spring 13 of FIG. 3 is directly pressed against the pressing ball 12, smooth rotation of the pressing ball 23 is ensured even in the pressurized state. Is done. As a result, the pressing ball 23 rotates on the peripheral surface of the welding wire a while pressing the welding wire a, and the sliding friction between the pressing ball 23 and the welding wire a is greatly reduced. Therefore, generation of wear powder due to wear of the welding wire a is reduced, and the inside of the welding wire feed hole 6 is kept clean. In addition, since the wear of the pressurized ball 23 is also suppressed, the welding wire a is pressed against the inner peripheral surface of the wire feed hole 6 with a constant pressing force, so that there is no loss.

The pressurizing ball 23 is preferably made of a hard insulating material such as ceramics in order to suppress the flow of electricity and the generation of sparks. Similarly, by forming the tubular portion 21 from a hard insulating material, damage to the pressurized ball 23 due to inflow of electricity, generation of spark, and the like can be suppressed.
When the insertion load of the welding wire a fed in the power supply tip 8 is set to about 130 gf, a spring having a spring pressure load of about 110 to 130 gf is used as the spring 25. One presser 20 is connected to the power supply tip 8
The welding wire a is pressed against the inner peripheral surface of the power supply tip 8 by the pressurizing ball 23 even when it is mounted on the power supply tip 8, so that a smooth current supply to the welding wire a is guaranteed. In addition, welding wire a
The pressure ball 23 rotates on the surface of the
The wear of the welding wire a due to the frictional contact with No. 3 is reduced, and the trouble due to the wear powder is eliminated. Furthermore,
When the plurality of pressers 20 are attached to the power supply tip 8 as illustrated, the feeding state of the welding wire a is stabilized.

That is, the welding wire a sent out from the spool 2 has a winding, and the wire feeding hole 6
It runs while meandering inside. When such a welding wire a is pressed against the inner peripheral surface of the wire feed hole 6 by one presser 20, the inner peripheral surface at that location is easily broken, and the destruction is concentrated at one place. Power supply to the welding wire a becomes unstable due to poor contact with the chip 8. As a result, the welding conditions fluctuate, making it difficult to form a sound weld bead e. In this regard, in the case where the welding wire a is pressed against the inner peripheral surface of the wire feed hole 6 by the plurality of pressers 20, the feeding points at which the welding wire a contacts the inner peripheral surface of the wire feed hole 6 are dispersed into a plurality. Therefore, destruction by spark etc. is 1
It is not necessary to concentrate on a place, and a stable power supply state is maintained for a long time. Further, even if the welding wire a moves in the wire feeding hole 6 due to meandering or vibration, the probability that the welding wire a is pressed against the inner wall of the wire feeding hole 6 by any of the holding members 20 increases, and the power supply defect. Is extremely small. As a result, generation of welding defects due to power supply defects or continuous occurrence thereof is suppressed. Further, even when the fixing of the single holding member 20 is loosened and a failure such as breakage occurs, the welding operation is not interrupted.

The holding member 20 is screwed into the holding member insertion hole 15. Therefore, when the presser 20 is damaged, the presser 20 can be taken out from the presser insertion hole 15 and replaced with a new presser 20 easily. Further, depending on the screwing amount of the holding member 20 into the holding member insertion hole 15, the pressing ball 2
The force with which the welding wire 3 presses the welding wire a against the inner peripheral surface of the holder insertion hole 15 is adjusted. Therefore, even if the diameter of the welding wire a slightly fluctuates, a sufficient pressing force can be obtained. Also,
When a welding wire a having a different standard is fed, a necessary pressing force can be obtained by mounting the holding member 20 having a different size. In the above, the holding tool 20 is attached to the power supply chip 8.
The welding torch equipped with was explained. However, presser 20
The object to which is attached is not limited to the power supply tip 8, and the presser 20 can be similarly attached to the contact tube 5 shown in FIG.

[0014]

EXAMPLE A 2.4 mm thick copper feed tip 8 having a wire feed hole 6 having a hole diameter of 1.4 mm was placed on a copper feed tip 8 having a thickness of 6 mm from the tip.
At three locations separated by 13 mm and 20 mm, presser insertion holes 15 with M3 female screws reaching the wire feed holes 6 were formed. A holding member 20 having an M3 male screw was screwed into each holding member insertion hole 15. As the presser 20, 11
Those having a spring pressure of 0 to 130 gf were used. Insert the welding wire a into the power supply tip 8 to which the presser 20 is attached,
When the wire insertion load at that time was measured with a weighing scale,
It was approximately constant at 130 gf, and the movement of the welding wire a was smooth.

Therefore, between the welding wire a and the base material A, 2
The base metal A was arc-welded at a welding speed of 3.5 m / min while applying a voltage of 3 V and supplying a standard current of 218 A.
When the voltage and the current were measured during welding, it was found that both the voltage and the current had very little fluctuation and the fluctuation width was greatly reduced. With the voltage and current thus fixed, the base material A
Was subjected to arc welding, so that the formed weld bead e was also sound with a constant width and height. Welding length 96
After welding the base material A by m, the welding torch 1 was disassembled, and the presser 20 was taken out from the power supply tip 8. The taken-out presser 20 had very little damage and was sufficiently resistant to reuse. Then, when welding using the welding torch 1 equipped with the same presser 20 was restarted,
The above welding was possible. Also, almost no damage due to sparks was observed on the inner peripheral surface of the wire feed hole 6 to which the resilience of the spring 25 was applied via the welding wire a.
No friction powder was detected inside the welding wire feed hole 6.

For comparison, the holding member 20 from which the spacer 26 has been removed is mounted on the power supply tip 8, and a similar welding wire a
Was subjected to a feed test and a welding test. In this case, since the pressure ball 23 was directly pressed against the welding wire a by the spring 25, the pressure ball 23 did not rotate and rubbed against the welding wire a. Therefore, the pressing state of the welding wire a against the inner peripheral surface of the wire feed hole 6 was likely to change irregularly, the welding voltage current and the welding current were easily changed, and the range of change was large. As a result, defects such as poor shape were generated in the obtained weld bead e. After welding the base material A for the same welding length of 96 m, the pressurized ball 23 was severely damaged to such an extent that it could not be reused.

[0017]

As described above, in the welding torch of the present invention, the presser having the spacer interposed between the spring and the pressurizing ball is detachably mounted on the contact tube or the power supply tip. . Therefore, the elasticity of the spring is applied to the pressurized ball via the spacer, and the pressurized ball presses the welding wire against the inner peripheral surface of the wire feed hole while rotating. That is, since there is no sliding friction between the welding wire and the pressurized ball, wear of the welded wire and the pressurized ball and generation of abrasion powder are suppressed, power is supplied to the welding wire under stable conditions, and the welding conditions are stabilized. . As a result, a sound bead is formed even in high-speed welding. In addition, the durability of the pressurized ball is reduced because the damage is reduced, and even if the pressurized ball is damaged, the replacement of the presser is easy, so that the welding workability is remarkably improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view of arc welding.

FIG. 2 is a sectional view of a conventional welding torch.

FIG. 3 is a cross-sectional view of a power supply tip for directly pressing a pressure ball by a spring.

FIG. 4 is a cross-sectional view of a part of a power supply chip according to the present invention in an axial direction (a) and a radial direction (b).

FIG. 5 is an axial cross-sectional view of a power supply tip showing that a welding wire is pressed against a wire feed hole with a pressurized ball.

FIG. 6 is a partial cross-sectional view of a power supply chip provided with a plurality of pressers.

[Explanation of symbols]

1: welding torch 2: spool 3: motor
4: feed roller 5: contact tube 6: wire feed hole 7: welding power supply 8: power supply tip 9: welding nozzle 10: outer tube 11: welding wire insertion tube 12, 23: pressurized ball 13, 25: spring 14 : Cap 15: Holder insertion hole 16: Female screw 17: Nut 20: Holder 21: Bottomed cylinder 22: Reduced diameter opening 24: Bottom wall 26: Spacer A: Base material a: Welding wire b: Wire tip
c: arc d: molten pool e: weld bead

Continuing on the front page (72) Inventor Hisashi Hori 1-34-1 Kambara, Kambara-cho, Anbara-gun, Shizuoka Prefecture Inside the Nippon Light Metal Co., Ltd. Group Technology Center (72) Mitsuo Tsuge 1-34-34 Kambara-cho, Kambara-cho, Anbara-gun, Shizuoka No. 1 Nippon Light Metal Co., Ltd. Group Technology Center

Claims (7)

[Claims] 1. A contact tube or a power supply tip through which a wire feed hole extending in the axial direction penetrates a central portion, and one or more contact tubes formed on a side wall of the contact tube or the power supply tip and reaching the wire feed hole. A holding tool insertion hole, a holding tool having a bottomed cylindrical portion screwed into the holding tool insertion hole, a spring having one end supported on the bottom wall of the bottomed cylindrical portion, and supporting the other end of the spring. A spacer, and a pressure ball which is in contact with the spacer and is prevented from being pulled out at the reduced diameter opening of the bottomed cylindrical portion, and the welding wire passing through the wire feeding hole by the repulsive force of the spring is used for the welding wire. A welding torch for high-speed MIG welding pressed against the inner peripheral surface of the wire feed hole. 2. A contact tube in which a female screw is engraved on the inner peripheral surface of the holding tool insertion hole, and a male screw engraved on the outer peripheral surface of the bottomed cylindrical portion is screwed with the female screw. The welding torch for high-speed MIG welding according to claim 1, wherein the presser is detachably attached to the power supply tip. 3. A force for pressing a welding wire against an inner peripheral surface of a wire feeding hole is adjusted by an amount of screwing of a holding tool into a contact tube or a power supply tip.
The welding torch for high-speed MIG welding described. 4. The welding torch for high-speed MIG welding according to claim 1, wherein a retaining nut is further screwed to a holding member attached to the contact tube or the power supply tip. 5. The welding torch for high-speed MIG welding according to claim 1, wherein a pressurized ball made of a hard insulating material is used. 6. The welding torch for high-speed MIG welding according to claim 1, wherein a plurality of pressers are arranged on a straight line extending in the axial direction of the contact tube or the power supply tip. 7. The high-speed device according to claim 1, wherein a plurality of pressers provided in an axial direction of the contact tube or the power supply tip are arranged at different positions in a circumferential direction of the contact tube or the power supply tip. Welding torch for MIG welding.