JP2000071074A - Tig arc welding robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a TIG arc welding robot with few fractures of an electrode. SOLUTION: A TIG arc torch T comprises an inner pipe 3 wherein a collet body is mounted to one end part and a hole is formed at a shaft center part, a collet presser which is spirally mounted to the inner pipe and presses/releases the collet against a collet body, a torch body 1 which restrains the position of a torch tip side of the inner pipe to a given position and slidably covers the inner pipe in a manner to be displaceable to a torch rear end side, and a coiled spring energizing the inner pipe to the torch tip side. An electrode 9 of the TIG arc torch and a material W to be welded are abutted, and the inner pipe is displaced to the torch rear end side against the energizing force of the coiled spring. The torch and the material to be welded are respectively separated while the current is applied between the electrode and the material to be welded for generating pilot arc. Thereafter a main arc is generated between the torch and the material to be welded for carrying out welding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial center of a collet provided with a frusto-conical projection at one end and a slit extending in the axial direction from the frusto-conical projection toward the other end. Insert the non-consumable electrode into the hole of the part, and reduce the diameter of the hole at the shaft center on the side of the truncated conical convex part of the collet to attach the non-consumable electrode to the free end of the welding robot. The present invention relates to an arranged TIG arc welding robot.

[0002]

2. Description of the Related Art Generally, in a TIG arc welding robot, a microcomputer is operated based on input data by a teaching operation to operate the robot, or the robot is operated by a fixed electric sequence controller. Welding is performed automatically. For example, as shown in FIG. 6, a TIG arc welding robot R in which a TIG arc torch T is arranged at a free end of a welding robot has been proposed. By the way, in a TIG arc welding robot, a non-consumable electrode is brought into contact with an object to be welded to start an arc, and a contact-type arc start method is provided. A so-called non-contact type arc start method, in which a high frequency voltage or a DC high voltage is supplied between the conductive electrode and the workpiece to start the arc, is appropriately selected and used. In these, the contact-type arc start method requires measures against electric high frequency and electric high voltage, and the contact-type arc start method ensures that the arc start is performed. There is a tendency for the start method to be frequently used.

Conventionally, this type of TIG arc welding robot uses, for example, a TIG arc torch as shown in FIG. That is, in FIG.
Is a torch body having a through hole in the shaft core, and 52 is a collet body having a through hole in the shaft core attached to the tip of the torch body 51.
A hole 521 that opens in two directions is provided, and an inclined concave portion 522 whose diameter decreases in the X1 direction is provided at an end of the hole 521 in the X1 direction. Reference numeral 53 denotes a gas nozzle attached to the tip of the torch body 51, and reference numeral 54 denotes a collet receiver which is removably attached to the shaft core of the torch body 51. Head 542
And a tubular portion 543 extending from the head 542 in the X1 direction.
It is made up of Further, the collet receiver 54 is provided with a hole 544 opening in the X2 direction.
An inclined recessed portion 545 whose diameter decreases in the X1 direction is provided at the end portion in the direction.

A first collet 55 is inserted into a hole 544 of the collet receiver 54. The first collet 55 is provided with a through hole 551 in a shaft portion, and has an inclined end at an end in the X1 direction. A frusto-conical projection 552 that fits into the recess 545 is provided, and X2
A slit 553 extending in the direction is provided. Reference numeral 56 denotes a collet press provided with a male screw 561 to be screwed into a female screw of the collet receiver 54, and 57 denotes a second collet inserted into the hole 521 of the collet body 52. Similarly to the collet 55, a hole 571 that opens in the X2 direction, a truncated conical protrusion 573 that fits into the inclined recess 522, and a slit 572 that extends in the X2 direction.
Is provided. The collet body 52, the collet receiver 54, the first collet 55, and the second collet 56 are provided with holes through which the non-consumable electrode 9 is inserted.

In the torch, for example, as shown in FIG. 7, a first collet 55 is disposed in a cylindrical portion 543 of a collet receiver 54, and a tip of a non-consumable electrode 9 inserted through the shaft core portion and a cylindrical portion. The collet presser 56 is spirally operated in the X1 direction with respect to the collet receiver 54 so that the interval between the end of the shape portion 543 and the end in the X1 direction becomes a desired value. That is, the collet presser 56 is moved in the X1 direction so that the frustoconical projection 552 of the first collet 55 is
4, the leading end of the slit 553 of the first collet 55 is reduced in diameter by the engagement of the concave and convex portions, and the non-consumable electrode 9 is fixed. Thereafter, as shown in FIG. 7, the second collet 57 is inserted into the hole 521 of the collet body 52, and then the non-consumable electrode 9 and the collet receiver 54, which are integrally mounted, are moved from the X2 direction side of the torch body 51. It is inserted in the X1 direction.
The end of the collet receiver 54 in the X1 direction is the second collet 5
When the collet receiver 54 that contacts the torch body 51 and is screwed with the torch body 51 is operated in the X1 direction, the uneven portion between the second collet 57 and the collet body 52 becomes X
And the slit 572 of the second collet 57
The tip of the torch is reduced in diameter, and the non-consumable electrode 9 is fixed. As a result, the respective parts of the torch are integrally formed.

As described above, the non-consumable electrode 9 is set to protrude from the gas nozzle 53 by a predetermined length.
An IG arc torch is fixed to the free end of the welding robot to form a TIG arc welding robot. This TIG
For example, a TIG arc welding robot is operated so that the electrode of the arc torch and the workpiece are in contact with each other. In this case, if the electrode and the workpiece come into extreme contact with each other, the electrode may be damaged.For example, a pressure sensor is provided on the torch holding portion of the welding robot, and after the electrode has approached the workpiece to some extent, Is gradually approached to the workpiece, and when the electrode comes into contact with the workpiece, a reaction force from the workpiece to the torch is detected by a pressure sensor, and the movement of the torch is stopped. Subsequently, the welding power source is activated to cause a short-circuit current to flow between the electrode and the workpiece, to separate the torch from the workpiece, and to generate a pilot arc. Welding is performed by generating a main arc between the arc torch and the workpiece.

[0007]

When operating a TIG arc welding robot, for example, so that the electrodes of the TIG arc torch come into contact with the work to be welded as described above, it is assumed that the electrodes have come into contact with the work to be welded. The welding robot is stopped by the pressure sensor and the detection signal, but in the micro state of contact between the electrode and the workpiece,
Since there are many time delays before the torch stops, the pressing force of the electrode against the work to be welded tends to be excessive, and the electrode tip is often damaged. Furthermore, as described above, after maintaining the electrode and the workpiece in contact with each other, a short-circuit current for generating a pilot arc flows between the electrode and the workpiece. If an unforeseen situation such as separation from the vehicle occurs, a pilot arc cannot be naturally generated. Furthermore, the use of a pressure sensor has increased the cost including the electric control device.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide an inexpensive TIG arc welding robot capable of performing reliable welding with less risk of damaging the electrodes of a TIG arc torch. It is to be.

[0009]

According to the first aspect of the present invention, a frusto-conical convex portion is provided at one end, and a slit extending from the frusto-conical convex portion toward the other end portion extends in the axial direction. A TIG arc torch for mounting the non-consumable electrode by inserting a non-consumable electrode into a hole at the axis of the collet, and reducing the diameter of the hole at the axis at the side of the truncated conical projection of the collet. Applied to a TIG arc welding robot located at the free end of a welding robot. The feature is that a collet body in which a hole is provided in the shaft center portion and an inclined concave portion corresponding to the convex portion of the collet is formed, and a collet body is attached to one end portion and a hole is provided in the shaft center portion. A collet presser screwed to the inner cylinder and pressed / released from the collet body to the collet inserted into the hole at the axial center of the inner cylinder; and a torch tip side of the inner cylinder. A TIG arc torch is constituted by a torch body that slidably encloses the inner cylinder so that the position is restricted to a predetermined position and is displaceable to the rear end side of the torch, and a coil spring that biases the inner cylinder toward the tip of the torch. Then, the electrode of the TIG arc torch is brought into contact with the work to be welded, and the inner cylinder is displaced to the rear end side of the torch against the urging force of the coil spring. While energizing between objects Serial TIG arc torch and by separating the welded object phase to generate a pilot arc, after this, is to perform welding by generating main arc between the TIG arc torch and the weld object.

[0010] The second invention is the first invention, wherein
The collet is directly pressed by a collet presser.

[0011] In a third aspect, in the first aspect,
It is characterized in that the collet is pressed via a cylindrical sleeve.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the coil spring is arranged so that a spring force between the torch body and the inner cylinder can be adjusted. And

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. In the TIG arc welding robot, a TI attached to a free end of the robot arm is used.
The vicinity of the G arc torch will be described in detail. 1 to 3
In the figure, reference numeral 1 denotes a torch body having a through hole 101 in a shaft core, and a hole 10 having a square cross section communicating with the through hole 101.
2 are opened in the X2 direction. 2 is a gas nozzle attached to the tip of the torch body 1.

Reference numeral 3 denotes an inner cylinder which is inserted into the shaft core of the torch body 1. A through hole 301 is formed in the shaft core, and a female screw 302 is formed on the end side of the through hole 301 in the X2 direction. A flange 303 is formed at the end of the inner cylinder 3 in the X2 direction. Further, a quadrangular hole 102 of the torch body 1 and a quadrangular projection 304 slidable in the X direction are formed on the outside of the inner cylinder 3 in the X1 direction following the flange portion 303. Furthermore, a female screw 305 is formed at the end of the inner cylinder 3 in the X1 direction.

Reference numeral 4 denotes a collet body attached to an end of the inner cylinder 3 in the X1 direction. For example, a male screw 401 of the collet body 4 is screwed into a female screw 305 of the inner cylinder 3 and integrally attached thereto. The collet body 4 is provided with a hole 402 that opens in the X2 direction, and an inclined recess 40 whose diameter decreases in the X1 direction is provided at the end of the hole 402 in the X1 direction.
3 and a non-consumable electrode 9 to be used on the shaft core.
Is formed slightly larger than the diameter of the through hole 404. Reference numeral 5 denotes a collet which is inserted into a through hole 301 of the shaft core of the inner cylinder 3.
Is provided with a through hole 501 for inserting the
At the end in the X1 direction, an inclined recess 40 of the collet body 4 is provided.
3 is provided with a frusto-conical projection 502, and a slit 503 in the longitudinal direction extending from the frusto-conical projection 502 in the X2 direction.

Reference numeral 6 denotes a cylindrical sleeve, which is inserted into the through hole 301 of the inner cylinder 3 such that the cylindrical sleeve 6 is located on the X2 direction side of the collet 5. 7 is a female screw 30 of the inner cylinder 3
2, a collet press provided with a male screw 701 screwed into
Reference numeral 8 denotes a bottomed adjusting tool screwed to the torch body 1, and a coil spring 11 is elastically mounted between the adjusting tool 8 and the inner cylinder 3. In addition, a large-diameter hole is provided in the bottomed shape of the adjusting tool 8, and the collet presser 7 is formed movably in the X direction with respect to the adjusting tool 8. Reference numeral 12 denotes a power supply attached to the collet retainer 7. For example, a so-called power cable for supplying a shielding gas and supplying electric power is connected to the power supply 12.

In the above-mentioned torch, for example, as shown in FIG. 1, first, an inner cylinder 3 having a collet body 4 attached to the tip thereof is inserted from the X2 direction side of the torch body 1 in the X1 direction. In this case, the protrusion 304 having a rectangular cross section of the inner cylinder 3 is inserted into the hole 102 having a rectangular cross section of the torch body 1. The collet 5 and the cylindrical sleeve 6 are arranged in the hole 301 of the shaft portion of the inner tube 3 and the collet presser 7 is screwed in the X1 direction with the non-consumable electrode 9 inserted through the shaft portion. It is operated to be. That is, the collet presser 7 is moved in the X1 direction, and the truncated cone-shaped convex portion 502 of the collet 5 engages with the inclined concave portion 403 of the collet body 4 through the cylindrical sleeve 6 to engage the concave portion. Due to the contact, the tip of the slit 503 of the collet 5 is reduced in diameter, and the non-consumable electrode 9 is fixed. That is, the non-consumable electrode 9 is fixed to the inner cylinder 3 such that the distance between the tip of the non-consumable electrode 9 and the end of the collet body 4 in the X1 direction becomes a desired value. Of course, the work of fixing the non-consumable electrode 9 to the inner cylinder 3 by the collet 5, the cylindrical sleeve 6, and the collet presser 7 can be performed at a place away from the arc torch, and thus integrally attached. Even if the non-consumable electrode 9 and the inner cylinder 3 are inserted from the X2 direction side of the torch body 1 in the X1 direction, the same state as described above is obtained.

Thereafter, the position of the adjusting tool 8 screwed to the torch body 1 is appropriately selected in the X direction, and the elasticity of the coil spring 11 for urging the inner cylinder 3 toward the torch tip via the adjusting tool 8 is desired. It is adjusted to the state. In the inner cylinder 3 urged toward the tip of the torch by the elastic force of the coil spring 11, the flange portion 303 of the inner cylinder 3 comes into contact with the torch body 1, and the position of the inner cylinder 3 on the tip of the torch is regulated. As described above, the non-consumable electrode 9 is set in a state of protruding from the gas nozzle 2 by a predetermined length. The TIG arc torch set in this way is fixed to the free end of the welding robot via an appropriate electric insulating member, thereby forming a TIG arc welding robot.

Next, the operation of the TIG arc welding robot will be described. The TIG arc torch and the workpiece are relatively moved, and it is assumed that the TIG arc welding robot having the TIG arc torch fixed at the free end is operated.

Now, the welding robot is operated so that the tip of the electrode 9 of the arc torch T is near a predetermined position of the workpiece W. For example, as shown in FIG. The electrode 9 is actuated so that the tip of the electrode 9 is located on the X1 side of the predetermined position of the workpiece W. That is, assuming that the workpiece W does not exist, the arc torch is moved by the welding robot from the X2 direction to the X1 direction in FIG. 4A, and the first torch shown in FIG.
Shall be positioned at the position of. In the above description, as shown in FIG. 4B, since the workpiece W is actually located at a predetermined position, the electrode 9 of the arc torch moves while the arc torch moves from the X2 direction to the X1 direction. However, the arc torch is further moved in the X1 direction and the first
Is positioned. That is, after the tip of the electrode 9 fixed to the inner cylinder 3 comes into contact with the workpiece W, the torch body 1 is moved by the movement amount h1 in the X1 direction.

Thereafter, the electric current is applied between the electrode 9 of the TIG arc torch and the workpiece W while the TIG arc torch is X2.
Moved in the direction. In the above case, the arc torch, that is, the torch body 1 is moved by the welding robot as shown in FIG.
When the torch body 1 is moved by the movement amount h1 in the X2 direction from the state shown in FIG. 5, the torch body 1 comes into contact with the lower surface of the flange portion 303 of the inner cylinder 3. [See FIG. 4 (C)]

Thereafter, the arc torch is further moved in the X2 direction by the welding robot. In this case, the torch body 1 and the inner cylinder 3 to which the electrode 9 is fixed are integrated with each other.
It is moved in two directions, for example, by a movement amount h2. As described above, while current is applied between the electrode 9 and the workpiece W, FIG.
When the electrode 9 is separated from the work to be welded from the state shown in (2), that is, the state where the electrode 9 is in contact with the work W, a so-called pilot arc is generated. Thereafter, welding is performed by generating a main arc between the TIG arc torch and the workpiece. Of course, in order to switch between the pilot arc and the main arc, the current and voltage values applied between the electrode 9 and the workpiece W are controlled in the same manner as before, and the welding shielding gas is supplied appropriately. .

If the tip of the non-consumable electrode 9 is deformed or consumed as the welding operation proceeds, the collet body 4 or the collet presser 7 is appropriately operated in the X direction,
The tip of the electrode 9 is formed and fixed again. Needless to say, in the above, the screwed state between the adjusting tool 8 and the torch body 1 is eliminated, and the inner cylinder 3 to the collet presser 7 integrally attached are removed.
In addition, the electrode 9 can be removed from the torch body 1, and the tip of the electrode 9 can be formed and fixed again at a location away from the arc torch.

Although the cylindrical sleeve 6 and the collet presser 7 are integrally formed by brazing, welding, etc., they can be formed separately. Furthermore, if the collet body 4 is formed separately, it is easy to produce the opening hole 402 and the inclined recess 403, but the collet body and the inner cylinder can be integrated regardless of this.

As described above, when the electrode 9 of the TIG arc torch contacts the workpiece W by, for example, the operation of the TIG arc welding robot, only a reaction force corresponding to the elasticity of the coil spring 11 acts on the electrode 9. Therefore, damage to the tip of the electrode is drastically reduced as compared with the related art. Further, while the electrode 9 is in contact with the workpiece W reliably due to the elasticity of the coil spring 11, the electrode 9 is energized between the electrode 9 and the workpiece W.
In order to separate the workpiece and the workpiece, a pilot arc is reliably generated, and thereafter, a main arc is generated between the TIG arc torch and the workpiece to ensure welding. Furthermore, since the conventionally required pressure sensor is not used, it is possible to save considerable costs required for the pressure sensor and the electric control device related thereto.

FIG. 5 is a view showing a modification of the present invention. In addition to the torch bodies 1 to 12 shown in FIG. 1, the following configuration is added. In this case, FIG.
The collet 5 and the collet presser 7 at
And the first collet presser 7. That is, in FIG. 5, a through hole 702 and a through hole 703 that is disposed on the X2 direction side of the through hole
And are drilled. An inclined concave portion 704 is formed at a connecting portion between the through holes 702 and 703. Reference numeral 13 denotes a second collet. The second collet 13 has an end portion in the X1 direction which fits into a through hole 131 formed in the shaft core and an inclined recess 704 of the first collet retainer 7. And a frusto-conical projection 132 formed on the
A slit 133 in a long axis direction extending in two directions is provided. Reference numeral 14 denotes an electrode pressing rod inserted into the through hole 131 of the second collet 13, reference numeral 15 denotes a second collet pressing, and the second collet pressing 15 is the X of the first collet pressing 7.
It is screwed to the end in two directions. In addition, with respect to the second collet presser 15 screwed to the first collet presser 7,
The electrode pressing rod 14 is formed so as to be movable in the X direction.

In FIG. 5, the electrode 9 is integrated with the inner cylinder 3 via the collet body 4, the first collet 5, the cylindrical sleeve 6, and the first collet presser 7, as in the case of FIG. Attached to Subsequently, the second collet 13 is disposed in the through hole 703 of the first collet retainer 7, and the electrode retainer rod 14 is inserted through the shaft core, and the electrode retainer rod 14 contacts the electrode 9. In this state, the second collet presser 15 is operated so as to advance in the X1 direction. That is, by moving the second collet presser 15 in the X1 direction,
The truncated conical convex portion 132 of the second collet 13 engages with the inclined concave portion 704 of the first collet presser 7, and the slit 133 of the second collet 13 is brought into contact by the engagement of the concave and convex portion.
Is reduced in diameter, and the electrode pressing rod 14 is fixed in a state of contact with the electrode 9. In the illustrated case, the power supply device 12 is attached to the first collet presser 7 by an appropriate attachment device, for example, a nut 16. Of course, the power supply 12 is appropriately supplied with power via a flexible cable. further,
The shielding gas for welding is appropriately supplied from, for example, a gas supply hole 17 formed in the torch body 1 or the like.

The TIG arc torch set as described above is fixed to the free end of the welding robot via an appropriate electric insulating member, thereby forming a TIG arc welding robot.

The operation of the TIG arc welding robot is the same as that shown in FIG. 4 and will not be described.

As shown in FIG. 5, the inner cylinder 3 is fixed by fixing the electrode holding rod 14 in contact with the electrode 9.
The fixing of the electrode 9 in the X2 direction with respect to the direction becomes strong. Furthermore, since the electrode pressing rod 14 is in contact with the end of the electrode 9 in the X2 direction and the end of the electrode 9 in the X2 direction is constrained in the radial direction, the long electrode 9 is used temporarily. Even in this case, a desired welding result can be obtained by stable restraining of the electrode 9 in the radial direction during the arc welding. Of course, if a concave portion that fits with the electrode 9 is provided in the axial core portion of the electrode holding rod 14, the electrode 9 can be arranged in the axial core portion of the inner cylinder 3.

[0031]

As is apparent from the above description, the TIG arc welding robot according to the present invention has a frusto-conical projection at one end and faces the frusto-conical projection toward the other end. The non-consumable electrode is inserted into a hole in the axial portion of the collet in which the slit extends in the axial direction, and the diameter of the hole in the axial portion on the side of the truncated conical convex portion of the collet is reduced to reduce the non-consumable. A TIG arc welding robot in which a TIG arc torch for mounting a neutral electrode is disposed at a free end of a welding robot, wherein a collet body is provided with a hole in an axial center portion and an inclined concave portion corresponding to a convex portion of the collet. And an inner cylinder having a collet body attached to one end and a hole in the shaft center, and a collet screwed into the inner cylinder and inserted into the hole in the shaft center of the inner cylinder to the collet body. Collet presser to press and release A torch tip position of the inner cylinder is regulated to a predetermined position, and a torch body slidably enclosing the inner cylinder so as to be displaceable toward the torch rear end side, and biases the inner cylinder toward the torch tip side. A TIG arc torch is constituted by the coil spring, the electrode of the TIG arc torch is brought into contact with the workpiece, and the inner cylinder is displaced toward the torch rear end side against the urging force of the coil spring. The TIG is supplied with electricity between the electrode of the TIG arc torch and the workpiece.
To separate the arc torch and the workpiece and generate a pilot arc, and then generate a main arc between the TIG arc torch and the workpiece to perform welding,
At the time of contact between the electrode of the TIG arc torch and the workpiece,
Only a reaction force corresponding to the elasticity of the coil spring acts on the electrode, and therefore, damage to the tip of the electrode is greatly reduced as compared with the related art. Furthermore, a pilot arc is reliably generated in order to separate the electrode and the workpiece while energizing the electrode and the workpiece W while the electrode is securely in contact with the workpiece by the elasticity of the coil spring. Thereafter, a main arc is generated between the TIG arc torch and the work to be welded, so that welding can be performed reliably. Furthermore, since the conventionally required pressure sensor is not used, it is possible to save considerable costs required for the pressure sensor and the electric control device related thereto. In summary, according to the present invention, it is possible to realize an inexpensive TIG arc welding robot that has a low risk of damaging the electrodes of the TIG arc torch and that can perform reliable welding.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of an embodiment of the present invention.

FIG. 2 is a perspective view of a collet 5 used in FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG. 1;

FIG. 4 is an explanatory view of a use state of FIG. 1;

FIG. 5 is a longitudinal sectional view showing a modification of the present invention.

FIG. 6 is a perspective view showing a TIG arc welding robot to which the present invention is applied.

FIG. 7 is a longitudinal sectional view showing a main part of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Torch body 3 Inner cylinder 4 Collet body 5 Collet 6 Cylindrical sleeve 7 Collet presser 9 Non-consumable electrode 11 Coil spring 12 Power supply tool 403 Inclined concave part formed in collet body 4 502 Truncated conical convex formed in collet 5 Part 503 slit formed in collet 5

Claims (4)

[Claims] 1. A frustum-shaped conical projection is provided at one end, and a slit facing the other end of the frusto-conical projection is not consumed in a hole in an axial center portion of a collet extending in an axial direction. TIG for mounting the non-consumable electrode by inserting a non-consumable electrode by reducing the hole diameter of the shaft center portion of the collet on the side of the truncated conical convex portion of the collet
TI with arc torch placed at free end of welding robot
In a G arc welding robot, a collet body in which a hole is provided in an axis portion and an inclined concave portion corresponding to a convex portion of the collet is formed, and a collet body is attached to one end portion and a hole is provided in the axis portion. An inner cylinder, a collet holder screwed to the inner cylinder, and a collet presser for pressing / releasing a collet inserted into a hole in a shaft portion of the inner cylinder with respect to the collet body; A TIG arc torch is constituted by a torch body which slidably encloses the inner cylinder so as to be displaceable toward the torch rear end side and a coil spring which biases the inner cylinder toward the torch front end side. The electrode of the TIG arc torch is brought into contact with the workpiece, and the inner cylinder is displaced toward the rear end of the torch against the urging force of the coil spring.
While the electric current is flowing between the electrode of the arc torch and the workpiece, the TI
TIG arc welding in which a G arc torch and a workpiece are separated to generate a pilot arc, and thereafter, a main arc is generated between the TIG arc torch and the workpiece to perform welding. robot. 2. The TIG arc welding robot according to claim 1, wherein the collet is directly pressed by a collet retainer. 3. The TIG arc welding robot according to claim 1, wherein the collet is pressed through a cylindrical sleeve. 4. The TIG arc welding robot according to claim 1, wherein the coil spring is provided such that a spring force between the torch body and the inner cylinder is adjustable.