Shield nozzle for TIG welding torch

Abstract

This invention provides a shield nozzle for a TIG welding torch that can improve the rectification of the shielding gas. [Solution] The shield nozzle for the TIG welding torch comprises a nozzle body which is a cylindrical alumina sintered body that expands towards the tip than towards the base; and a screen which is a disc-shaped structure made of multiple stacked metal meshes and partitions the inside of the nozzle body. The nozzle body has a base end which is cylindrical and has a female thread portion configured to fit into the male thread portion of the gas lens collet body of the TIG welding torch; an expanded portion which is cylindrical and expands from a first inner diameter to a second inner diameter toward the tip; and a tip portion which is cylindrical and has a second inner diameter. The cleaner fits in a convex shape toward the base side to the curved portion of the inner circumferential surface of the nozzle body extending from the expanded portion to the tip, which begins to curve and narrow toward the base side from the second inner diameter.

Description

Technical Field

[0005] ,

[0001] This specification discloses a technology related to a shield nozzle for a TIG welding torch.

Background Art

[0002] The shield nozzle for a TIG welding torch is attached to a gas lens collet body and rectifies the shield gas discharged from the gas lens collet body. An extended type of shield nozzle that discharges the shield gas from a discharge port that is expanded compared to the cross-section of the gas lens collet body is known (for example, refer to Patent Document 1).

[0003] <00000!2>Patent Document 1 describes an extended type of shield nozzle. The shield nozzle of Patent Document 1 includes a nozzle body made of glass and a screen that partitions the inside of the nozzle body. The nozzle body of Patent Document 1 has a cylindrical shape that expands from the base end side towards the tip end side. The screen of Patent Document 1 is formed by connecting two dish-shaped metal meshes back-to-back with an annular fitting. The annular fitting of Patent Document 1 has a through-hole for passing an electrode rod.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In expandable shield nozzles, turbulence is likely to occur during the expansion of the shield gas flow path, thus requiring improved rectification of the shield gas flow. In the shield nozzle described in Patent Document 1, the nozzle body is made of glass, which has the problem of the screen being prone to misalignment. In addition, the shield nozzle described in Patent Document 1 has the problem that the dish-shaped metal mesh in the screen is prone to deformation. Misalignment and deformation of the screen in a shield nozzle are factors that cause turbulence in the shield gas, which reduces welding quality. [Means for solving the problem]

[0006] The technologies disclosed herein can be implemented in the following forms:

[0007] (1) One embodiment disclosed herein is a shield nozzle used in a TIG welding torch to rectify the flow of shielding gas. This shield nozzle comprises a nozzle body which is a cylindrical alumina sintered body that expands towards the tip than towards the base end; and a screen which is a disc-shaped structure formed by stacking a plurality of metal meshes and partitions the inside of the nozzle body. The nozzle body has a base end which is cylindrical and has a female thread configured to fit into the male thread portion of the gas lens collet body of the TIG welding torch; an expanded portion which is cylindrical and adjacent to the base end on the tip side of the base end and expands toward the tip side from a first inner diameter to a second inner diameter; and a tip portion which is cylindrical and adjacent to the expanded portion on the tip side of the expanded portion on the tip side of the expanded portion and has the second inner diameter. The screen is fitted in a convex shape toward the base end to the curved portion of the inner circumferential surface of the nozzle body, which extends from the expanded portion to the tip portion and begins to curve and narrow toward the base end from the second inner diameter. With this type of shield nozzle, the nozzle body is made of alumina crystal, which has smaller dimensional errors during manufacturing and a rougher surface compared to glass, so the misalignment of the screen relative to the nozzle body can be suppressed compared to the case of glass. In addition, since the screen, which is made of multiple stacked metal meshes, is fitted in a convex shape toward the base end to the curved portion of the inner circumferential surface, misalignment and deformation of the screen can be suppressed. As a result, the rectification of the shield gas can be improved.

[0008] (2) In the shield nozzle of the above form, the screen may be formed by resistance spot welding the centers of the stacked plurality of metal meshes, and may have resistance spot welds where adjacent metal meshes are joined together in the plurality of metal meshes; and a through hole that penetrates the center of the resistance spot weld and is configured to fit onto the electrode rod of the TIG welding torch. With this form of shield nozzle, the structure of combining a plurality of metal meshes and the structure for passing the electrode rod through the screen can be formed by the resistance spot welds and through hole of the screen without using any parts other than metal mesh. This makes it possible to reduce the weight of the shield nozzle.

[0009] (3) In the shield nozzle of the above form, the metal mesh has a plain weave structure of vertical and horizontal wires, and the vertical and horizontal wires may be diffusion-bonded at adjacent portions to each other. With this form of shield nozzle, the unraveling of the vertical and horizontal wires is prevented, and thus deformation of the screen can be further suppressed.

[0010] (4) In the shield nozzle of the above embodiment, the plurality of metal meshes may include a first metal mesh located at the base end of the screen, and a plurality of second metal meshes located on the tip side of the screen, relative to the first metal mesh. The first metal mesh has a coarser mesh than the second metal mesh. The outer diameter of the first metal mesh is larger than the inner diameter of the second. The outer diameter of the second metal mesh is smaller than the inner diameter of the second. With this embodiment of the shield nozzle, displacement and deformation of the screen can be further suppressed. In addition, the work of assembling the screen to the nozzle body can be easily performed.

[0011] (5) In the above-described shield nozzle, if the female thread portion has a female thread structure with a nominal diameter of 9 / 16 inch, it is preferable that the relationship between the length L1 of the expansion portion and the second inner diameter D2 satisfies L1 / D2 ≥ 0.237. With this configuration of shield nozzle, it is possible to ensure the rectification of the shield gas while making the shield nozzle smaller and lighter.

[0012] The technology disclosed herein can be implemented in various forms different from shield nozzles for TIG welding torches. For example, the technology disclosed herein can be implemented in the form of a TIG welding apparatus, a TIG welding torch, a nozzle body for a shield nozzle, a screen for a shield nozzle, and so on. [Brief explanation of the drawing]

[0013] [Figure 1] This is an explanatory diagram showing a TIG welding torch. [Figure 2] This is a cross-sectional view showing details of the shield nozzle. [Figure 3] This is a front view showing the shield nozzle. [Figure 4] This is a cross-sectional view showing the details of the screen. [Figure 5] This is an explanatory diagram showing how to assemble the screen onto the nozzle body. [Figure 6] This table shows the test results evaluating the effect of the nozzle body length L1 and inner diameter D2 on the rectification of the shielding gas. [Figure 7] This table shows the test results evaluating the effect of the nozzle body length L1 and inner diameter D2 on the rectification of the shielding gas. [Modes for carrying out the invention]

[0014] Figure 1 is an explanatory diagram showing a TIG welding torch 100. Figure 2 is a cross-sectional view showing details of the shield nozzle 200. Figure 3 is a front view showing the shield nozzle 200.

[0015] The TIG welding torch 100 is a tool used for TIG (Tungsten Inert Gas) welding. The TIG welding torch 100 includes a handle 110, a neck 120, a head 130, a back cap 140, a gas lens collet body 160, an electrode rod 180, and a shield nozzle 200.

[0016] The handle 110 of the TIG welding torch 100 is the part that an operator holds by hand to operate the TIG welding torch 100. The handle 110 has a cylindrical shape. A cable 105 for supplying power and shielding gas (e.g., argon gas, helium gas, etc.) to the gas lens collet body 160 is inserted into the handle 110.

[0017] The neck 120 of the TIG welding torch 100 connects the handle 110 and the head 130. In this embodiment, the neck 120 is configured to be deformable so as to adjust the attachment angle between the handle 110 and the head 130. Inside the neck 120, a conduction path for supplying power to the head 130 is formed. Inside the neck 120, a gas flow path for supplying shielding gas to the head 130 is formed.

[0018] The head 130 of the TIG welding torch 100 holds the back cap 140 and the gas lens collet body 160. The head 130 has a cylindrical shape. Inside the head 130, a conduction path for supplying power to the gas lens collet body 160 is formed. Inside the head 130, a gas flow path for supplying shielding gas to the gas lens collet body 160 is formed.

[0019] The back cap 140 of the TIG welding torch 100 seals the rear end side of the head 130. The TIG welding torch 100 is configured such that an operator can fix the electrode rod 180 to the gas lens collet body 160 by tightening the back cap 140.

[0020] The gas lens collet body 160 holds the electrode rod 180 and discharges shielding gas around the electrode rod 180. The gas lens collet body 160 is a cylindrical metal body. As shown in FIG. 2, the gas lens collet body 160 includes a male screw portion 162 and a gas lens portion 168.

[0021] The male screw portion 162 of the gas lens collet body 160 is a portion where a thread that fits into the shield nozzle 200 is formed on the outer peripheral surface. The central axis of the male screw portion 162 coincides with the central axis AX1 of the electrode rod 180.

[0022] <管理编号: The gas lens portion 168 of the gas lens collet body 160 rectifies the shielding gas so that the shielding gas discharged from the gas lens collet body 160 around the electrode rod 180 becomes laminar flow through a doughnut-shaped metal mesh centered on the electrode rod 180.

[0023] The electrode rod 180 of the TIG welding torch 100 is a rod-shaped tungsten electrode. The base end side of the electrode rod 180 is held inside the gas lens collet body 160 in a conductive state. The tip end side of the electrode rod 180 protrudes outside the shield nozzle 200.

[0024] The shield nozzle 200 of the TIG welding torch 100 is attached to the gas lens collet body 160. The shield nozzle 200 rectifies the shielding gas discharged from the gas lens collet body 160. The shield nozzle 200 is an extended type shield nozzle that discharges the shielding gas from an outlet that is extended from the cross section of the gas lens collet body 160. As shown in FIGS. 2 and 3, the shield nozzle 200 includes a nozzle body 300 and a screen 400.

[0025] The nozzle body 300 of the shield nozzle 200 is an alumina sintered body that forms a cylindrical shape, with the tip 308 side being more expanded than the base end 302 side. The base end 302 is an open end that abuts against the head 130. The tip 308 is an open end that opens in the direction in which the electrode rod 180 protrudes. The nozzle body 300 has a base end 310, an expanded portion 320, and a tip portion 330.

[0026] The base end 310 of the nozzle body 300 forms a base end 302. The base end 310 is cylindrical in shape and has an internal female thread portion 312. The central axis of the base end 310 coincides with the central axis AX1 of the electrode rod 180. The female thread portion 312 is configured to fit into the male thread portion 162 of the gas lens collet body 160 of the TIG welding torch 100. In this embodiment, the male thread portion 162 has a female thread structure with a nominal diameter of 9 / 16 inch (Unified Fine Thread "9 / 16-18UNF").

[0027] The expansion portion 320 of the nozzle body 300 is adjacent to the base end portion 310 on the coaxial axis toward the tip end portion 308. The expansion portion 320 has a cylindrical shape that expands toward the tip end portion 308 from an inner diameter D1 (first inner diameter) to an inner diameter D2 (second inner diameter). The central axis of the expansion portion 320 coincides with the central axis AX1 of the electrode rod 180.

[0028] The tip portion 330 of the nozzle body 300 forms the tip 308. The tip portion 330 is adjacent to the expansion portion 320 on the coaxial side of the expansion portion 320 towards the tip 308. The tip portion 330 is cylindrical with an inner diameter D2. The central axis of the tip portion 330 coincides with the central axis AX1 of the electrode rod 180.

[0029] From the viewpoint of miniaturizing and lightening the shield nozzle 200, it is preferable, and even more preferable, that the length L1 of the extension portion 320 in the axial direction (central axis AX1 in Figure 2) of the nozzle body 300 be shorter than the length L2 of the tip portion 330. However, from the viewpoint of ensuring the rectification of the shield gas, if the female screw portion 312 has a female screw structure with a nominal diameter of 9 / 16 inch, it is preferable that the relationship between the length L1 of the extension portion 320 and the inner diameter D2 of the tip portion 330 satisfies L1 / D2 ≥ 0.237, and even more preferable that L1 / D2 ≥ 0.263. The relationship between the value of L1 / D2 and the rectification of the shield gas will be described later.

[0030] The nozzle body 300 has an adjacent portion 322, a curved portion 324, an inclined surface 326, a curved portion 328, and an inner circumferential surface 332 as an inner circumferential surface extending from the expansion portion 320 to the tip portion 330. The adjacent portion 322 is adjacent to the female thread portion 312 of the base end portion 310 and has an inner diameter D1, which is the first inner diameter. The curved portion 324 is a portion that is curved convexly inward in the radial direction of the expansion portion 320 and begins to expand from the inner diameter D1 toward the tip 308. The inclined surface 326 is a surface that is inclined toward the tip 308 and connects the curved portion 324 and the curved portion 328. The curved portion 328 is a portion that is curved convexly outward in the radial direction of the expansion portion 320 and begins to contract from the inner diameter D2 toward the base end 302. The inner circumferential surface 332 is adjacent to the curved portion 328 and has an inner diameter D2, which is a second inner diameter.

[0031] The screen 400 of the shield nozzle 200 partitions the inside of the nozzle body 300. As shown in Figure 2, the screen 400 fits into the curved portion 328 of the expanded portion 320 of the nozzle body 300 in a convex curve toward the base end 302. As a result, the screen 400 rectifies the shield gas so that the shield gas released from the tip 308 of the nozzle body 300 around the electrode rod 180 becomes a laminar flow.

[0032] Figure 4 is a cross-sectional view showing details of the screen 400. The shape of the screen 400 shown in Figure 4 is shown before it is assembled to the nozzle body 300. The screen 400 is a disc-shaped structure formed by stacking multiple metal meshes 410. The screen 400 has resistance spot welds 402 and through holes 404.

[0033] The screen 400 is formed by stacking a plurality of disc-shaped metal meshes 410. In this embodiment, the plurality of metal meshes 410 include five metal meshes 410a, 410b, 410c, 410d, and 410e in order from the base end 302 side. In this description, the reference numeral "410" is used to refer collectively to each of the plurality of metal meshes in the screen 400, and the reference numeral "a, b, c, ..." is used to distinguish each of the plurality of metal meshes in the screen 400.

[0034] Each of the metal mesh 410 has a plain weave structure 415 consisting of vertical wires 417 and horizontal wires 419. The vertical wires 417 and horizontal wires 419 of the metal mesh are diffusion-bonded at adjacent portions 418. In this embodiment, the material of the metal mesh 410 is stainless steel.

[0035] The metal mesh 410a of screen 400 is the first metal mesh located at the base end 302 side of screen 400. The metal meshes 410b to 410e of screen 400 are a plurality of second metal meshes located closer to the tip 308 side than the first metal mesh 410.

[0036] In this embodiment, the mesh count of metal mesh 410a is 40 mesh (40 openings per inch), and the mesh count of metal meshes 410b to 410e is 100 mesh (100 openings per inch). In this embodiment, the outer diameter D5 of metal mesh 410a is the same as the outer diameter D6 of metal meshes 410b to 410e. Before the screen 400 is assembled to the nozzle body 300, the outer diameter D5 of metal mesh 410a and the outer diameter D6 of metal meshes 410b to 410e are approximately 1 to 2% larger than the inner diameter D2 of the tip portion 330 of the nozzle body 300.

[0037] The resistance spot welds 402 of the screen 400 are weld marks formed by resistance spot welding at a single point in the center of multiple stacked metal meshes 410. In the resistance spot welds 402, adjacent metal meshes 410 are joined together. As shown in Figure 4, the resistance spot welds 402 are compressed in the thickness direction more than the unwelded areas 406 that are not resistance spot welded. A through hole 404 is formed in the center of the resistance spot welds 402. The resistance spot welds 402 form a donut shape surrounding the through hole 404. In this embodiment, the outer diameter of the resistance spot welds 402 is approximately 7.0 mm.

[0038] The through-hole 404 in the screen 400 is formed by punching out the center of the resistance spot weld 402. The through-hole 404 penetrates the center of the resistance spot weld 402. The through-hole 404 is configured to fit onto the electrode rod 180. In this embodiment, the diameter of the through-hole 404 is approximately 2.5 mm.

[0039] When manufacturing the screen 400, the screen 400 manufacturer prepares a metal mesh sheet, which is the material for the metal mesh 410. The manufacturer then heat-treats the metal mesh sheet. This causes diffusion bonding at the adjacent parts 418 between the vertical wires 417 and horizontal wires 419 in the metal mesh sheet. Next, the worker punches out the metal mesh sheet to create multiple metal meshes 410. Then, the manufacturer forms a resistance spot weld 402 by spot welding a single point in the center of the stacked metal meshes 410. Finally, the manufacturer forms through holes 404 by punching out the centers of the multiple metal meshes 410, which are also the centers of the resistance spot weld 402. Through these processes, the screen 400 is completed.

[0040] Figure 5 is an explanatory diagram showing how the screen 400 is assembled to the nozzle body 300. When assembling the screen 400 to the nozzle body 300, the manufacturer of the shield nozzle 200 prepares the nozzle body 300, the screen 400, and the jig 500.

[0041] The jig 500 comprises a first cylindrical portion 510, a second cylindrical portion 520, and a central axis 530. The first cylindrical portion 510 has an outer diameter approximately the same as the tip portion 330 of the nozzle body 300. The second cylindrical portion 520 has an outer diameter that loosely fits into the inner diameter D2 of the tip portion 330 of the nozzle body 300. The height of the second cylindrical portion 520 is approximately the same as the length L2 of the tip portion 330. The second cylindrical portion 520 is coaxial with the first cylindrical portion 510 and adjacent to the first cylindrical portion 510 above. The central axis 530 protrudes above the second cylindrical portion 520. The central axis 530 is located on the axis of the first cylindrical portion 510 and the second cylindrical portion 520.

[0042] The manufacturer of the shield nozzle 200 moves the screen 400 to a position where it contacts the upper surface 522 of the second cylindrical portion 520, with the central axis 530 of the jig 500 passing through the through hole 404 of the screen 400. Then the manufacturer moves the nozzle body 300 to a position where the tip 308 contacts the upper surface 512 of the first cylindrical portion 510. This assembles the screen 400 to the nozzle body 300 as shown in Figure 2. After that, the worker removes the shield nozzle 200 from the jig 500. The shield nozzle 200 is completed after these steps.

[0043] Figures 6 and 7 are tables showing test results evaluating the effect of the length L1 and inner diameter D2 of the nozzle body 30 on the rectification of the shielding gas. In the evaluation tests shown in Figures 6 and 7, the testers prepared multiple shielding nozzles 200 as samples, each with a different length L1 and inner diameter D2 of the nozzle body 300. The length L1 and inner diameter D2 of each sample are as shown in Figures 6 and 7. The values ​​for each part of each sample are L0=11.5mm, L2=10mm, and D1=14.8mm. The female threaded part 312 of each sample is a Unified Fine Thread "9 / 16-18UNF". The screen 400 of each sample is a combination of a 40-mesh metal mesh 410a and 100-mesh metal meshes 410b to 410e.

[0044] The testers visualized the flow of shielding gas emitted from the TIG welding torch 100, to which each sample was attached, using Schlieren imaging. The components of the TIG welding torch 100 used in the evaluation test are as follows: Head 130: "1726" manufactured by Miller, USA. Back cap 140: "57Y04" manufactured by Miller, USA. Gas lens collet body 160: Mirror Corporation "45V44" (USA)

[0045] The testers visually confirmed the flow of the shielding gas as it appeared in the images captured by Schlieren. Then, the testers evaluated the rectification of the shielding gas based on the turbulence generated in the evaluation range from the tip 308 of the nozzle body 300 to 20 mm of the shielding gas flow emitted from the shielding nozzle 200.

[0046] In the test results shown in Figures 6 and 7, a "Good" rating indicates that no noticeable turbulence occurred within the evaluation range of the shielding gas. A "Acceptable" rating indicates that although slight turbulence was observed within the evaluation range of the shielding gas, the generally required welding quality could be ensured. A "Poor" rating indicates that significant turbulence was observed within the evaluation range of the shielding gas, and there is a possibility that the generally required welding quality could not be ensured. From the test results shown in Figures 6 and 7, it can be seen that, from the viewpoint of ensuring the rectification of the shielding gas, the relationship between the length L1 and inner diameter D2 of the nozzle body 30 preferably satisfies L1 / D2≧0.237, and even more preferably satisfies L1 / D2≧0.263.

[0047] As described above, the shield nozzle 200 has a nozzle body 300 made of alumina crystals, which has smaller dimensional tolerances during manufacturing and a rougher surface compared to glass, thus suppressing positional displacement of the screen 400 relative to the nozzle body 300 compared to the case of glass. Furthermore, since the screen 400, which is made of multiple stacked metal meshes 410, is fitted to the curved portion 328 of the inner circumference in a convex curve toward the base end 302, positional displacement and deformation of the screen 400 can be suppressed. This improves the rectification of the shield gas.

[0048] Furthermore, the shield nozzle 200 allows for the creation of a structure that combines multiple metal meshes 410 and a structure that allows the electrode rod 180 to pass through the screen 400, without using any parts other than the metal meshes 410, through the resistance spot welds 402 and through holes 404 of the screen 400. This makes it possible to reduce the weight of the shield nozzle 200.

[0049] Furthermore, with the shield nozzle 200, the vertical lines 417 and horizontal lines 419 of the metal mesh 410 in the screen 400 are diffusion-bonded at adjacent portions 418. Therefore, the unraveling of the vertical lines 417 and horizontal lines 419 is prevented, and deformation of the screen 400 can be further suppressed.

[0050] Furthermore, in the case of the shield nozzle 200, if the female thread portion 312 has a female thread structure with a nominal diameter of 9 / 16 inch, it is preferable that the relationship between the length L1 and the inner diameter D2 in the nozzle body 300 satisfies L1 / D2 ≥ 0.237, and more preferably L1 / D2 ≥ 0.263. This makes it possible to ensure the rectification of the shield gas while making the shield nozzle 200 smaller and lighter.

[0051] The technologies disclosed herein are not limited to the embodiments, examples, and modifications described above. The technologies disclosed herein can be implemented in various configurations without departing from the spirit of the invention. The technical features of the embodiments, examples, and modifications described above that correspond to the technical features of each form described in the summary of the invention may be substituted and combined in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. Furthermore, technical features not described as essential in this specification may be deleted as necessary.

[0052] The invention described above can be applied to a shield nozzle 200 having a female thread portion 312 with a nominal diameter other than 9 / 16 inch.

[0053] The number of meshes, the number of metal meshes 410 in the screen 400, and the outer diameter can be changed as appropriate. If there is one 40-mesh metal mesh 410 used in the screen 400, from the viewpoint of shielding gas flow straightening, five 100-mesh metal meshes 410 are preferable to three. In this case, it is preferable that the metal mesh 410a located at the base end 302 side is 40 mesh, but any of the metal meshes 410 sandwiched in the middle of the multiple metal meshes 410 in the screen 400 may also be 40 mesh.

[0054] Furthermore, from the viewpoint of improving the workability of assembling the screen 400 to the nozzle body 300, it is preferable that the metal mesh 410a has a coarser mesh than the metal meshes 410b to 410e. In addition, before assembling the screen 400 to the nozzle body 300, it is preferable that the outer diameter D5 of the metal mesh 410a is about 1-2% larger than the inner diameter D2 of the nozzle body 300, and the outer diameter D6 of the metal meshes 410b to 410e is about 1-2% smaller than the inner diameter D2 of the nozzle body 300. [Explanation of Symbols]

[0055] 30…Nozzle body 100...TIG welding torch 105…Cable 110... Handle 120... neck 130... Head 140...back cap 160... Gas lens collet body 162...Male screw part 168...Gas lens section 180...electrode rod 200... Shield nozzle 300... Nozzle body 302...Proximal end 308... Tip 310...Proximal end 312...Female thread section 320... Expansion section 322...Adjacent part 324... Curved section 326…Slope surface 328... Curved section 330...Tip 332…Inner peripheral surface 400… screens 402... Resistance spot weld 404…Through hole 406... Unwelded section 410, 400a~400e…Metal mesh 415…Plain weave structure 417…Vertical line 418...Adjacent part 419... horizontal line 500... Jig 510...First cylindrical section 512…Top surface 520...Second cylindrical section 522…Top surface 530…Central axis AX1…center axis D1...Inner diameter D2...Inner diameter D5…Outer diameter D6…Outer diameter

Claims

1. A shield nozzle used in a TIG welding torch to rectify the flow of shielding gas, The nozzle body is an alumina sintered body that forms a cylindrical shape, with the tip being wider than the base, A disc-shaped structure formed by stacking multiple metal meshes, which partitions the inside of the nozzle body, and Equipped with, The nozzle body is A cylindrical base end having a female thread portion configured to fit into the male thread portion of the gas lens collet body of the TIG welding torch, An expanded portion is cylindrical in shape, coaxially adjacent to the base end on the tip side of the base end, and expanding toward the tip side from a first inner diameter to a second inner diameter, A tip portion having a second inner diameter is located coaxially adjacent to the expanded portion on the tip side of the expanded portion and forms a cylindrical shape. It has, The screen is a shield nozzle in which the screen is curved in a convex shape toward the base end, and fits into a curved portion of the inner circumferential surface of the nozzle body extending from the expanded portion to the tip portion, which begins to curve and narrow toward the base end from the second inner diameter.

2. A shield nozzle according to claim 1, The aforementioned screen is A resistance spot weld is formed by resistance spot welding the centers of the stacked plurality of metal meshes, and adjacent metal meshes in the plurality of metal meshes are joined together. A through hole that penetrates the center of the resistance spot weld and is configured to fit onto the electrode rod of the TIG welding torch, A shield nozzle having

3. A shield nozzle according to claim 1, The aforementioned metal mesh has a plain weave structure consisting of vertical and horizontal wires. A shield nozzle in which the aforementioned vertical line and the aforementioned horizontal line are diffusion-bonded at their adjacent portions.

4. A shield nozzle according to claim 1, The aforementioned multiple metal meshes are The screen includes a first metal mesh located at the base end, In the screen, a plurality of second metal meshes located on the tip side of the first metal mesh and Includes, The first metal mesh has a coarser mesh than the second metal mesh. The outer diameter of the first metal mesh is larger than the inner diameter of the second, A shield nozzle in which the outer diameter of the second metal mesh is smaller than the inner diameter of the second metal mesh.

5. A shield nozzle according to claims 1 to 4, A shield nozzle in which, when the female thread portion has a female thread structure with a nominal diameter of 9 / 16 inch, the relationship between the length L1 of the expansion portion and the second inner diameter D2 satisfies L1 / D2 ≥ 0.237.

Images