TIG welding torch comprising narrowed nozzle

Abstract

To provide a TIG welding torch comprising a narrowed nozzle, which can improve safety and a welding quality.SOLUTION: A TIG welding torch comprising a narrowed nozzle is provided with a conductive electrode nozzle 1, provided at a tip part of a torch body 7, which stores a narrowed nozzle 2, and an earth cable connection terminal 3 electrically connected to the electrode nozzle 1. The electrode nozzle 1 comprises a cylindrical nozzle body 1A and a beam nozzle 1B detachably attached to the nozzle body 1A. The beam nozzle 1B comprises a conical tapered part 1d having a nozzle hole 1c at a tip thereof, and a cylindrical part 1f connected to a rear end of the tapered part 1d and having a screw part that is screwed to the nozzle body 1A. The tapered part 1d has a tip edge 1g whose base material can be contacted with the whole circumference of the nozzle hole 1c and also has a first gas exhaust hole 1h on a conical peripheral side surface thereof. The nozzle body 1A has a second gas exhaust hole 1b on a cylindrical peripheral side surface thereof.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a TIG welding torch equipped with a constricting nozzle, and more particularly to a TIG welding torch suitable for spot welding. [Background technology]

[0002] Conventionally, TIG welding generally involves generating an arc between the base material, which is connected to one electrode of the welding power source, and a tungsten electrode rod, which is connected to the other electrode, while flowing an inert shielding gas between the electrode rod and the base material. By covering the electrode rod, arc, and molten pool with shielding gas, the molten metal is protected from adverse effects of the intrusion of oxygen, nitrogen, etc. from the atmosphere, and the electrode rod is prevented from oxidizing and being worn down.

[0003] Conventional TIG welding requires the laborious process of connecting the base material to one of the electrodes of the welding power source, and also requires skill because the torch must be held so that the distance between the electrode and the base material is constant to produce a good weld.

[0004] In view of this, the present inventor has proposed a TIG welding torch with a constricted nozzle, which does not require a connection between the base metal and a welding power source and enables even an unskilled person to perform good welding (Patent Documents 1 to 3).

[0005] As shown in Figures 1 to 3, each of these TIG welding torches with a constriction nozzle includes a metal electrode nozzle 1 and a constriction nozzle 2 housed within the electrode nozzle 1. An earth cable connection terminal 3 electrically connected to the electrode nozzle 1 is connected to one electrode terminal of a welding power source (not shown) via an earth cable 4, and an electrode rod 5 is connected to the other electrode terminal of the welding power source via an electric cable.

[0006] As shown in FIG. 4, for example, the constriction nozzle 2 has a support protrusion 2a protruding from the inner peripheral surface which concentrically supports an electrode rod 5 inserted into the constriction nozzle 2, and a gap 2b between adjacent support protrusions 2a is configured as a passage for a shielding gas G (Patent Documents 1 to 5, Non-Patent Document 1, etc.).

[0007] In the TIG welding torches with constriction nozzle described in Patent Documents 1 to 3, the electrode nozzle 1 is connected to an electrode terminal (usually a cathode terminal) of a welding power source, so that the electrode nozzle 1 is brought into contact with the base metal W during welding, and the base metal W is earthed to the welding power source via the electrode nozzle 1. Therefore, there is no need to earth the base metal W as in the past. In addition, the electrode rod 5 is fixed at a position a predetermined distance inward from the tip of the electrode nozzle 1 by the collet 6 in the torch body, so that the worker holding the torch does not need to adjust the distance between the base metal W and the electrode rod 5 during manual welding, and stable and good welding can be performed even by those who are not skilled in TIG welding. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. WO2020 / 137949 [Patent Document 2] Patent Publication No. 2022-308 [Patent Document 3] Patent Publication No. 2022-70060 [Patent Document 4] JP 2012-139704 A [Patent Document 5] International Publication No. WO2013 / 157036 [Non-patent literature]

[0009] [Non-Patent Document 1] Kyohei Konishi, Masaya Shigeta, Manabu Tanaka, Akihisa Murata, Yusuke Murata, Anthony B. Murphy, Japan Society of Light Metal Welding, Vol. 55, No. 6, 2017, p. 227-232. Summary of the Invention [Problem to be solved by the invention]

[0010] In the TIG welding torch with a constriction nozzle shown in FIG. 1, a gas vent groove 1a is formed in the tip surface of the electrode nozzle 1 so that the shielding gas G supplied into the electrode nozzle 1 can be discharged from both ends of the electrode nozzle 1, one on the tip side and the other on the side away from the tip, and a gas exhaust hole 1b is formed in the deepest part of the internal space of the electrode nozzle 1 (the upper part of the figure).

[0011] During welding, the tip of the electrode nozzle 1 is brought into contact with the base metal W, and the gas vent groove 1a quickly discharges metal vapor to the outside when an arc is generated, thereby suppressing wear on the electrode rod 5 caused by the metal vapor. In addition, by providing a gas exhaust hole 1b at the end of the electrode nozzle 1 away from the tip, the shielding gas G that has not been exhausted through the gas vent groove 1a flows around the arc and around the molten metal, and is then discharged from the gas exhaust hole 1b, thereby reliably and satisfactorily protecting the molten metal and arc from the air.

[0012] However, the metal vapor discharged from the gas vent groove 1a is deposited on the base metal W, leaving radial metal vapor marks around the welding spot on the surface of the base metal W. The metal vapor marks do not adversely affect the welding quality, but they do impair the appearance. In addition, the arc at the time of ignition leaks out from the gas vent groove 1a and may damage the eyes if viewed with the naked eye, so protective glasses must be worn.

[0013] As shown in FIG. 2, the above-mentioned problem in appearance can be solved by not forming a gas vent groove on the tip surface of the electrode nozzle 1.

[0014] However, as shown in FIG. 2, in an embodiment in which no gas vent groove is formed on the tip surface of the electrode nozzle 1 and a gas exhaust hole 1b is formed only in the deepest part of the internal space of the electrode nozzle 1 at a position away from the tip of the electrode nozzle 1, metal vapor is not immediately discharged, and this may accelerate wear of the electrode rod 5 due to metal vapor. In addition, when no gas vent groove is formed on the tip surface of the electrode nozzle 1, a force is applied to the tip of the electrode nozzle 1 from the inside of the electrode nozzle 1 to the side due to the gas pressure of the shielding gas G injected during spot welding, and the torch may be displaced to the side (in the direction of the arrow X) during welding. Furthermore, when no gas vent groove 1a is formed on the tip surface of the electrode nozzle 1, soot due to metal vapor accumulates inside the electrode nozzle 1.

[0015] Therefore, a main object of the present invention is to provide a TIG welding torch equipped with a constriction nozzle that is an improvement over the conventional TIG welding torch equipped with the constriction nozzle and can solve the various problems described above. [Means for solving the problem]

[0016] In order to achieve the above object, a TIG welding torch with a constriction nozzle according to one embodiment of the present invention comprises a torch body, a collet that is detachably inserted into the torch body, holds an electrode rod, and passes a shielding gas along the electrode rod, a constriction nozzle that is provided on the tip side of the collet and supports the electrode rod concentrically, and passes the shielding gas through a gap between the electrode rod and the constriction nozzle and sprays the shielding gas toward the tip of the electrode rod, a conductive electrode nozzle that is provided at the tip of the torch body and houses the constriction nozzle, and a conductive electrode nozzle that is connected to the electrode nozzle. and an earth cable connection terminal electrically connected to the electrode nozzle, the electrode nozzle comprises a cylindrical nozzle body and a beam nozzle detachably attached to the nozzle body, the beam nozzle comprises a conical tapered portion having a nozzle hole at its tip, and a tubular portion connected to the rear end of the tapered portion and having a screw portion for screwing into the nozzle body, the tapered portion has a tip edge around the entire circumference of the nozzle hole that can abut against a base material and has a first gas discharge hole on its conical peripheral side surface, and the nozzle body has a second gas discharge hole on its cylindrical peripheral side surface.

[0017] The tip of the constriction nozzle may be disposed at a position spaced inward a predetermined distance from the tip position of the electrode nozzle, and the first gas discharge hole may be provided to the side of the tip position of the constriction nozzle.

[0018] The first gas discharge hole may be formed so that the gas discharge direction is perpendicular to the axis of the constricting nozzle and does not face toward an imaginary plane that is in contact with the tip edge of the electrode nozzle.

[0019] The first gas discharge hole may have a gas ejection direction perpendicular to an axis of the constricting nozzle.

[0020] The tip of the constriction nozzle may be located 3 to 4 mm inward from the tip of the electrode nozzle. The constriction nozzle may be connected to the tip of the collet via an extension adapter. Effect of the Invention

[0021] According to the TIG welding torch equipped with the constriction nozzle of the present invention, when an arc is ignited, the space between the electrode nozzle and the base metal is blocked, and the shielding gas sprayed from the constriction nozzle is discharged from the first gas discharge hole 1h and the second gas discharge hole 1b. Since the space between the electrode nozzle and the base metal is blocked, metal vapor during welding does not leak from between the electrode nozzle and the base metal, and no deposition marks of metal vapor are left around the welding spot.

[0022] In addition, since the shielding gas can be discharged from the first gas discharge hole provided between the second gas discharge hole and the tip of the electrode nozzle, even if the space between the electrode nozzle and the base metal is blocked, it is possible to prevent the torch held by the tip of the electrode nozzle from being pushed sideways and shifted out of position due to the gas pressure of the shielding gas from the inside.

[0023] In addition, the metal vapor generated when the arc is ignited is discharged from the first gas exhaust hole and the second gas exhaust hole together with the shielding gas, thereby preventing the metal vapor from stagnating inside the electrode nozzle and causing soot to accumulate on the inner surface of the electrode nozzle.

[0024] In addition, since the arc can be prevented from leaking out from between the electrode nozzle and the base metal, the worker's eyes will not be damaged even if he does not wear protective glasses. In particular, since the arc is generated between the part of the electrode rod protruding from the tip of the constriction nozzle and the base metal, the arc can be effectively prevented from leaking out by disposing the first gas exhaust hole to the side of the tip position of the constriction nozzle. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a vertical sectional front view showing an example of a TIG welding torch equipped with a conventional constriction nozzle. [Diagram 2] FIG. 11 is a vertical sectional front view showing another example of a TIG welding torch equipped with a conventional constriction nozzle. [Diagram 3] FIG. 11 is a vertical sectional front view showing still another example of a TIG welding torch equipped with a conventional constriction nozzle. [Figure 4]4 shows a constriction nozzle which is a component of the torch shown in FIG. 2, with FIG. 4(A) being a front view, FIG. 4(B) being a longitudinal front view, and FIG. 4(C) being a CC sectional view of FIG. 4(B). [Diagram 5] 1 is a vertical sectional front view showing a first embodiment of a TIG welding torch equipped with a constriction nozzle according to the present invention. [Figure 6] FIG. 6 is a perspective view of the first embodiment shown in FIG. [Figure 7] FIG. 7 is an enlarged view of part VII in FIG. 5. [Figure 8] FIG. 4 is a vertical sectional front view showing a second embodiment of a TIG welding torch equipped with a constricting nozzle according to the present invention. [Figure 9] FIG. 9 is a perspective view of the second embodiment shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] A first embodiment of a TIG welding torch having a constricting nozzle according to the present invention will be described below with reference to Figures 5 to 7. Note that the same components are designated by the same reference numerals throughout the drawings, including those in the prior art.

[0027] 5 to 7, the TIG welding torch according to the first embodiment of the present invention comprises a torch body 7, a collet 6 that is detachably inserted into the torch body 7, holds the electrode rod 5, and passes shielding gas G along the electrode rod 5, a constriction nozzle 2 that is provided at the tip side of the collet 6, supports the electrode rod 5 concentrically, and passes the shielding gas G through a gap 2b between the electrode rod 5 and the constriction nozzle 2 to inject the shielding gas G toward the tip of the electrode rod 5, a conductive electrode nozzle 1 that is provided at the tip of the torch body 7 and houses the constriction nozzle 2, and an earth cable connection terminal 3 that is electrically connected to the electrode nozzle 1.

[0028] In the illustrated example, the torch body 7 is cylindrical and is composed of an upper part 7a and a lower part 7b that are connected to each other. The torch body 7 is made of a non-conductive insulating material (for example, a resin material).

[0029] A one-touch tube joint 8 and a torch cable connection terminal 9 are attached to the rear end of the collet 6. A gas tube (not shown) is connected to the tube joint 8 to supply shielding gas G. The torch cable connection terminal 9 is connected to an electrode terminal (e.g., positive electrode) of a welding power source (not shown) by an electric cable (not shown). A gripping cylinder 10 for the operator to grip is fixed to the upper part 7a of the torch body 7. The gripping cylinder 10 in the illustrated example is made of transparent polycarbonate.

[0030] The constricting nozzle 2 is connected to the tip side of the collet 6 via a nozzle mounting bracket 11. The rear end side of the nozzle mounting bracket 11 is screwed to the tip side of the collet 6, and the tip side is screwed to the constricting nozzle 2. The nozzle mounting bracket 11 is fixed inside the lower part 7b of the torch body 7. By screwing the collet 6 into the nozzle mounting bracket 11, the collet 6 is tightened to clamp the tungsten electrode rod 5.

[0031] The constriction nozzle 2 is similar to the conventional known examples described in JP 2022-308 A and JP 2022-70060 A, and as shown in FIG. 4, the support protrusions 2a protruding from the inner surface hold the electrode rod 5 concentrically, and the gaps 2b between the support protrusions 2a are configured as passages for the shielding gas G.

[0032] A cylindrical earth connection fitting 12 is fixed to the outer periphery of the lower part 7b of the torch body 7, and the electrode nozzle 1 is attached to the earth connection fitting 12 by screw connection. The earth connection fitting 12 is made of a metal material (conductive material). The earth connection fitting 12 is fitted onto the lower part 7b and fixed to the lower part 7b by embedded screws or the like. An earth cable connection terminal 3 is attached to the earth connection fitting 12. The earth cable connection terminal 3 is connected via an earth cable 4 to an electrode terminal (e.g., a cathode terminal) of a welding power source (not shown).

[0033] The electrode nozzle 1 comprises a cylindrical nozzle body 1A and a beam nozzle 1B detachably attached to the nozzle body 1A. The nozzle body 1A is screwed and electrically connected to an earth connection fitting 12. The nozzle body 1A and the beam nozzle 1B can be made of the same metal material or different metal materials.

[0034] The beam nozzle 1B comprises a conical tapered portion 1d having a nozzle hole 1c at its tip, and a cylindrical portion 1f having a screw portion 1e connected to the rear end of the tapered portion 1d for detachably screwing to the nozzle body 1A.

[0035] It may be necessary to change the diameter of the nozzle hole 1c of the beam nozzle 1B depending on the magnitude of the welding current used for the arc discharge. In such cases, the beam nozzle 1B can be replaced with one having a nozzle hole 1c with a diameter that corresponds to the magnitude of the welding current.

[0036] The tapered portion 1d has a tip edge 1g around the entire periphery of the nozzle hole 1c that can come into contact with the base metal W. By bringing the tip edge 1g into contact with the base metal W, it is possible to prevent the shielding gas G from leaking between the tip of the electrode nozzle 1 and the base metal W. The tip edge 1g can be a flat surface. A first gas exhaust hole 1h is provided on the conical peripheral side surface of the tapered portion 1d.

[0037] The first gas discharge hole 1h is preferably provided on the side of the tip position of the constriction nozzle 2. Here, the side of the tip position of the constriction nozzle 2 means a radial direction centered on the axis of the constriction nozzle 2. The axis of the constriction nozzle 2 substantially coincides with the axis of the electrode rod 5. The first gas discharge hole 1h can be provided at a position where a straight line perpendicular to the axis of the constriction nozzle 2 passes at the tip position of the constriction nozzle 2. The hole size (diameter) of the first gas discharge hole 1h can be, for example, 1.3 to 2.0 mm.

[0038] Second gas discharge holes 1b are provided on the cylindrical circumferential side surface of nozzle body 1A. In the illustrated example, four second gas discharge holes 1b are provided, but the number may be set appropriately.

[0039] The tip position of the constriction nozzle 2 is disposed at a predetermined distance H1 (3 to 4 mm) from the tip position of the electrode nozzle 1. By bringing the tip position of the constriction nozzle 2 close to the tip position of the electrode nozzle 1 to set the predetermined distance H1, the effect of discharging metal vapor by the shielding gas G through the first gas exhaust hole 1h is enhanced. The tip of the electrode rod 5 protrudes from the tip of the constriction nozzle 2, and is clamped by the collet 6 so as to be fixed at a position spaced inward from the tip position of the electrode nozzle 1 by a distance H2 (for example, 0.3 to 1.0 mm). The tip position of the electrode nozzle 1 corresponds to the surface position of the base material W with which the tip edge 1g of the electrode nozzle 1 abuts.

[0040] The first gas exhaust hole 1h is formed so that the gas exhaust direction is perpendicular to the axis of the constricting nozzle 2 (corresponding to the axis of the electrode rod 5) and does not face an imaginary plane that is in contact with the tip edge of the electrode nozzle 1. This imaginary plane corresponds to the surface of the base material W with which the electrode nozzle 1 comes into contact during welding.

[0041] The second gas discharge hole 1b is provided at the bottom of the internal space of the electrode nozzle 1, at a position sufficiently far rearward from the tip position of the constricting nozzle 2 by a distance H3 (for example, 15 to 20 mm).

[0042] The hole diameter and the number of the first gas exhaust holes 1h and the second gas exhaust holes 1b can be appropriately set according to the objects to be welded. In the illustrated example, four first gas exhaust holes 1h and four second gas exhaust holes 1b are provided, and all of them have the same hole diameter.

[0043] In the TIG welding torch equipped with the constriction nozzle having the above configuration, the tip edge 1g of the tip of the beam nozzle 1B is brought into contact with the base metal W during spot welding to close the gap between the electrode nozzle 1 and the base metal W. By bringing the electrode nozzle 1 into contact with the base metal W, the electrode nozzle 1 and the base metal W are electrically connected, and the base metal W is connected to a welding power source not shown. In this state, the shielding gas G is sprayed from the constriction nozzle 2. After a certain time (e.g., 0.2 seconds) has elapsed since the start of the spraying of the shielding gas G, an arc is ignited between the electrode rod 5 and the base metal W for a certain time (e.g., 0.2 seconds). After the arc is stopped, a certain time (e.g., 0.1 seconds) has elapsed, and the spraying of the shielding gas is stopped to end the spot welding.

[0044] As described above, when the arc is ignited, the space between the electrode nozzle 1 and the base metal W is blocked, so that the shielding gas G sprayed from the constriction nozzle 2 is discharged from the first gas discharge hole 1h and the second gas discharge hole 1b. Since the space between the electrode nozzle 1 and the base metal W is blocked, metal vapor during welding does not leak from between the electrode nozzle 1 and the base metal W, so that no deposition marks of metal vapor are left around the welding spot.

[0045] In addition, since the shielding gas G can be discharged from the first gas discharge hole 1h provided between the second gas discharge hole 1b and the tip of the electrode nozzle 1, even if the space between the electrode nozzle 1 and the base material W is blocked, it is possible to prevent the torch held by the tip of the electrode nozzle 1 from being pushed sideways and shifted out of position due to the gas pressure of the shielding gas G from the inside.

[0046] In addition, the metal vapor generated at the time of arc ignition is discharged from the first gas exhaust hole 1h and the second gas exhaust hole 1b together with the shielding gas G, thereby preventing the metal vapor from accumulating inside the electrode nozzle 1 and causing soot to accumulate on the inner surface of the electrode nozzle 1.

[0047] In addition, since leakage of the arc from between the electrode nozzle 1 and the base metal W can be prevented, the worker's eyes will not be damaged even if he does not wear protective glasses. In particular, since the arc is generated between the part of the electrode rod 5 protruding from the tip of the constriction nozzle 2 and the base metal W, by disposing the first gas exhaust hole 1h to the side of the tip position of the constriction nozzle 2, leakage of the arc can be effectively prevented.

[0048] A comparative test was conducted to investigate the state of the electrode rod and the state of the molten pool after four arc strikes under the following conditions for an example according to the above-mentioned first embodiment and a conventional comparative example (the configuration shown in FIG. 2) that does not have a gas exhaust groove at the tip of the electrode nozzle.

[0049] The test conditions for both the embodiment and the comparative example were as follows: arc length: 1 mm, electrode rod diameter: 1.6 mm, taper angle of the electrode rod tip: 40°, arc ignition time: 0.2 seconds, base material (thickness): C2600 (0.8 mm), type and flow rate of shielding gas: Ar 1.5 liters / min, welding current: 100 A to 200 A (increasing by 20 A each), and two types of inner diameters of nozzle hole, 2.0 mm and 5.0 mm, were used.

[0050] As a result of the above comparison test, when the inner diameter of the nozzle hole was 5.0 mm, no significant difference was observed in the appearance of the electrode rod between the embodiment and the comparative example. On the other hand, when the inner diameter of the nozzle hole was 2.0 mm, the electrode rod of the embodiment was not dirty and maintained its initial state, but the comparative example had a dirty appearance due to metal vapor adhering to it. In addition, when the inner diameter of the nozzle hole was 5 mm, the part of the molten pool directly below the electrode rod (the center of the molten pool) was recessed in the comparative example, but raised in the embodiment, so it was found that the embodiment reduced the number of holes during welding.

[0051] FIG. 8 is a cross-sectional view showing a second embodiment of a TIG welding torch equipped with a constriction nozzle according to the present invention, and FIG. 9 is a perspective view showing the appearance thereof. The second embodiment differs from the first embodiment in that the electrode nozzle 1 is equipped with a water-cooled jacket 1C. The water-cooled jacket 1C is made of metal (conductive) and is connected between the nozzle body 1A and the beam nozzle 1B. In the water-cooled jacket 1C, a flow path 1Cc through which cooling water passes is formed between the inner cylinder 1Ca and the outer cylinder 1Cb, and a cooling water inlet 1Cd and outlet 1Ce are attached to the outer cylinder 1Cb. In addition, the constriction nozzle 2 is connected to the nozzle mounting bracket 11 via the extension adapter 2c, so that the distance between the tip position of the constriction nozzle 2 and the tip position of the electrode nozzle 1 can be set to a predetermined distance (3 to 4 mm). The other configurations are the same as those of the first embodiment, and the water-cooled jacket 1C is described in detail in JP 2022-70060 A and is publicly known, so detailed description will be omitted.

[0052] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0053] 1 Electrode nozzle 1A Nozzle Body 1B Beam nozzle 1C Water Cooling Jacket 1b Second gas exhaust hole 1c Nozzle hole 1d Narrowed section 1e Screw part 1f Cylindrical part 1h First gas exhaust hole 1g Tip edge 2. Constriction nozzle 2c Extension Adapter 3 Earth cable connection terminal 4 Earth cable 5 Electrode rod 6. Collette 7 Torch body

Claims

1. Torch body and a collet that is detachably attached to the torch body, holds an electrode rod, and passes a shielding gas along the electrode rod; a constriction nozzle provided at a tip side of the collet, which supports the electrode rod concentrically and passes the shielding gas through a gap between the electrode rod and the constriction nozzle, and injects the shielding gas toward the tip of the electrode rod; a conductive electrode nozzle provided at a tip of the torch body and accommodating the constriction nozzle; an earth cable connection terminal electrically connected to the electrode nozzle; the electrode nozzle comprises a cylindrical nozzle body and a beam nozzle detachably attached to the nozzle body, the beam nozzle comprises a cone-shaped tapered portion having a nozzle hole at a tip, and a cylindrical portion having a screw portion connected to a rear end of the tapered portion and for screwing into the nozzle body, the tapered portion has a tip edge around the entire periphery of the nozzle hole that can come into contact with a base material, and has a first gas discharge hole on a conical peripheral side surface, The nozzle body has a second gas discharge hole on a cylindrical peripheral side surface. A TIG welding torch with a constricting nozzle.

2. the tip of the constriction nozzle is disposed at a position spaced a predetermined distance inward from the tip position of the electrode nozzle, 2. The TIG welding torch equipped with a constriction nozzle according to claim 1, wherein the first gas discharge hole is provided on a side of a tip position of the constriction nozzle.

3. 3. A TIG welding torch equipped with a constriction nozzle according to claim 2, wherein the first gas discharge hole is formed so that a gas discharge direction is perpendicular to an axis of the constriction nozzle and does not face toward an imaginary plane that is in contact with a tip edge of the electrode nozzle.

4. 4. The TIG welding torch equipped with a constriction nozzle according to claim 3, wherein the first gas discharge hole has a gas ejection direction oriented in a direction perpendicular to an axis of the constriction nozzle.

5. 3. A TIG welding torch equipped with a constriction nozzle according to claim 2, wherein a tip position of the constriction nozzle is located 3 to 4 mm inside a tip position of the electrode nozzle.

6. 6. The TIG welding torch equipped with a constriction nozzle according to claim 5, wherein the constriction nozzle is connected to a tip side of the collet via an extension adapter.

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