Shield nozzle for TIG welding torch

Abstract

A shield nozzle for a TIG welding torch capable of improving the rectification of a shield gas is provided. [Solution] A shield nozzle for a TIG welding torch includes a nozzle body made of an alumina sintered body having a cylindrical shape with a tip side expanded more than a base side; and a screen having a disk shape formed by stacking a plurality of metal meshes and partitioning the inside of the nozzle body. The nozzle body has a cylindrical base end portion having a female thread portion configured to be able to fit into a male thread portion of a gas lens collet body of a TIG welding torch; a cylindrical expansion portion expanding from a first inner diameter to a second inner diameter toward the tip side; and a cylindrical tip portion having the second inner diameter. The screen fits in a state of being curved convexly toward the base end side with a curved portion of the inner circumferential surface of the nozzle body from the expansion portion to the tip portion, the curved portion curving from the second inner diameter toward the base end side and beginning to shrink.

Description

[Technical field]

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

[0002] A 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. As a shield nozzle, an expansion type shield nozzle that discharges shield gas from a discharge port that is expanded more than the cross section of the gas lens collet body is known (for example, see Patent Document 1).

[0003] Patent Document 1 describes an expansion type shield nozzle. The shield nozzle of Patent Document 1 includes a glass nozzle body and a screen that divides the inside of the nozzle body. The nozzle body of Patent Document 1 is cylindrical with the tip side expanded more than the base side. The screen of Patent Document 1 is made of two dish-shaped metal meshes connected back to back with a ring-shaped metal fitting. The ring-shaped metal fitting of Patent Document 1 has a through hole for passing an electrode rod through. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 9,338,873 Summary of the Invention [Problem to be solved by the invention]

[0005] In an expansion type shield nozzle, turbulence is likely to occur in the process of expanding the flow path of the shield gas, so there is a demand for improving the rectification of the shield gas. In the shield nozzle of Patent Document 1, the nozzle body is made of glass, so there is a problem that the screen is easily displaced. In addition, in the shield nozzle of Patent Document 1, there is a problem that the dish-shaped metal mesh in the screen is easily deformed. Displacement and deformation of the screen in the shield nozzle are factors that cause turbulence in the shield gas, reducing the welding quality. [Means for solving the problem]

[0006] The technology disclosed in this specification can be realized in the following forms. One embodiment disclosed in the present specification is a shield nozzle for rectifying a shield gas. The shield nozzle includes a nozzle body that is an alumina sintered body having a cylindrical shape with a tip side expanded from a base end side; and a screen that is a disk shape formed by stacking a plurality of metal meshes and divides the inside of the nozzle body. The nozzle body includes a cylindrical base end having a female thread configured to be fitted into a male thread part of a gas lens collet body of the TIG welding torch; an expansion part that is adjacent to the base end coaxially on the tip side from the base end and expands from a first inner diameter to a second inner diameter toward the tip side; and a cylindrical tip end that is adjacent to the expansion part coaxially on the tip side from the expansion part and has the second inner diameter. The screen fits in a curved portion of the inner circumferential surface of the nozzle body from the expansion part to the tip part, which curves from the second inner diameter toward the base end side and starts to shrink, in a state of being curved convexly toward the base end side. The relationship between the length L1 of the extension portion and the second inner diameter D2 satisfies L1 / D2≧0.237. According to this form of shield nozzle, the nozzle body is made of alumina crystals, which has a rough surface and a smaller dimensional error during manufacturing compared to glass, so that the positional deviation of the screen relative to the nozzle body can be suppressed compared to the case of glass. In addition, the screen, which is made of multiple laminated metal meshes, fits into the curved portion of the inner circumferential surface in a convex curved state toward the base end side, so that the positional deviation and deformation of the screen can be suppressed. This can improve the rectification of the shield gas.

[0007] (1) One embodiment disclosed in the present specification is a shield nozzle used in a TIG welding torch for straightening a shield gas. The shield nozzle includes a nozzle body made of an alumina sintered body having a cylindrical shape with a tip side expanded from a base side; and a screen having a disk shape formed by stacking a plurality of metal meshes and partitioning the inside of the nozzle body. The nozzle body includes a cylindrical base end having a female thread configured to be able to fit into a male thread of a gas lens collet body of the TIG welding torch; an extension part that is adjacent to the base end coaxially on the tip side from the base end and expands from a first inner diameter to a second inner diameter toward the tip side; and a cylindrical tip end that is adjacent to the extension part coaxially on the tip side from the extension part and has the second inner diameter. The screen fits in a curved portion of the inner circumferential surface of the nozzle body from the expansion portion to the tip portion, which curves from the second inner diameter toward the base end and starts to shrink. According to this form of shield nozzle, the nozzle body is made of alumina crystals, which has a rough surface and has a smaller dimensional error during manufacturing than glass, so that the positional deviation of the screen with respect to the nozzle body can be suppressed compared to the case of glass. In addition, the screen, which is made of a plurality of laminated metal meshes, fits in a curved portion of the inner circumferential surface in a convex shape toward the base end, so that the positional deviation and deformation of the screen can be suppressed. This can improve the rectification of the shield gas.

[0008] (2) In the shield nozzle of the above embodiment, the screen may have a resistance spot welded portion formed by resistance spot welding the centers of the stacked metal meshes, where adjacent metal meshes of the metal meshes are joined together, and a through hole penetrating the center of the resistance spot welded portion and configured to be able to fit an electrode rod of the TIG welding torch. According to the shield nozzle of this embodiment, the structure for combining the multiple metal meshes and the structure for penetrating the electrode rod in the screen can be formed by the resistance spot welded portion and the through hole of the screen without using any parts other than the metal meshes. This makes it possible to reduce the weight of the shield nozzle.

[0009] (3) In the shield nozzle of the above embodiment, the metal mesh may have a plain weave structure of vertical and horizontal lines, and the vertical and horizontal lines may be diffusion-bonded at adjacent portions of the vertical and horizontal lines. With this shield nozzle, the vertical and horizontal lines are prevented from coming undone, so that 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 end of the screen on the base end side; and a plurality of second metal meshes located on the screen closer to the tip side than 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 second inner diameter. The outer diameter of the second metal mesh is smaller than the second inner diameter. According to the shield nozzle of this embodiment, the positional deviation and deformation of the screen can be further suppressed. Also, the operation of assembling the screen to the nozzle body can be easily performed.

[0011] (5) In the shield nozzle of the above embodiment, when the female screw portion 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 and the second inner diameter D2 satisfies L1 / D2 ≧ 0.237. According to the shield nozzle of this embodiment, it is possible to ensure the rectification of the shield gas while reducing the size and weight of the shield nozzle.

[0012] The technology disclosed in this specification can be realized in various forms other than the shield nozzle for a TIG welding torch, for example, in the form of a TIG welding device, a TIG welding torch, a nozzle body of a shield nozzle, a screen of a shield nozzle, etc. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an explanatory diagram showing a TIG welding torch. [Diagram 2] FIG. 4 is a cross-sectional view showing details of a shield nozzle. [Diagram 3] FIG. [Figure 4] FIG. 4 is a cross-sectional view showing the details of the screen. [Diagram 5] FIG. 11 is an explanatory diagram showing how the screen is assembled to the nozzle body. [Figure 6] 1 is a table showing the results of a test evaluating the effect of the length L1 and the inner diameter D2 of the nozzle body on the straightening of the shielding gas. [Figure 7] 1 is a table showing the results of a test evaluating the effect of the length L1 and the inner diameter D2 of the nozzle body on the straightening of the shielding gas. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Fig. 1 is an explanatory diagram showing a TIG welding torch 100. Fig. 2 is a cross-sectional view showing details of a shield nozzle 200. Fig. 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 a part that an operator holds in his / her hand to operate the TIG welding torch 100. The handle 110 has a cylindrical shape. A cable 105 that supplies a power source and a 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 that the attachment angle between the handle 110 and the head 130 can be adjusted. A conductive 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 inside the neck 120.

[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 conductive path is formed for supplying power to the gas lens collet body 160. Inside the head 130, a gas flow path is formed for supplying shielding gas to the gas lens collet body 160.

[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 so that an operator can fix the electrode rod 180 to the gas lens collet body 160 by tightening the back cap 140.

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

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

[0022] Gas lens portion 168 of gas lens collet body 160 rectifies the flow of shielding gas so that the shielding gas discharged from gas lens collet body 160 to the periphery of electrode rod 180 becomes a laminar flow through a donut-shaped metal mesh centered on electrode rod 180.

[0023] The electrode rod 180 of the TIG welding torch 100 is a rod-shaped electrode made of tungsten. The base end side of the electrode rod 180 is held in a conductive state inside the gas lens collet body 160. The tip 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 shield gas discharged from the gas lens collet body 160. The shield nozzle 200 is an expansion type shield nozzle that discharges the shield gas from a discharge port that is expanded more than 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 having a cylindrical shape with a tip 308 side expanded further than a 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 end 330.

[0026] The base end 310 of the nozzle body 300 forms the base end 302. The base end 310 is cylindrical with a female thread portion 312 on the inside. 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 be able 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 inches (Unified fine thread "9 / 16-18UNF").

[0027] The expansion section 320 of the nozzle body 300 is adjacent to the base end 310 on the same axis on the tip 308 side of the base end 310. The expansion section 320 has a cylindrical shape that expands from an inner diameter D1 (first inner diameter) to an inner diameter D2 (second inner diameter) toward the tip 308 side. The central axis of the expansion section 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 extension portion 320 on the same axis on the tip 308 side of the extension portion 320. 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 making the shield nozzle 200 smaller and lighter, in the axial direction of the nozzle body 300 (center axis AX1 in FIG. 2), the length L1 of the extension portion 320 is preferably shorter than the length L2 of the tip portion 330, and the shorter the better. However, from the viewpoint of ensuring the rectification of the shield gas, when the female thread portion 312 has a female thread structure with a nominal diameter of 9 / 16 inches, the relationship between the length L1 of the extension portion 320 and the inner diameter D2 of the tip portion 330 preferably satisfies L1 / D2≧0.237, and more preferably satisfies 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 peripheral surface 332 as an inner peripheral surface extending from the expansion portion 320 to the tip portion 330. The adjacent portion 322 is adjacent to the female screw portion 312 of the base end portion 310 and has an inner diameter D1 which is a first inner diameter. The curved portion 324 is a portion that starts to expand from the inner diameter D1 toward the tip end 308 side in a state where it is curved in a convex manner toward the radially inward direction of the expansion portion 320. The inclined surface 326 is a surface that inclines toward the tip end 308 side and connects between the curved portion 324 and the curved portion 328. The curved portion 328 is a portion that starts to reduce from the inner diameter D2 toward the base end 302 side in a state where it is curved in a convex manner toward the radially outward direction of the expansion portion 320. The inner circumferential surface 332 is adjacent to the curved portion 328 and has a second inner diameter, that is, an inner diameter D2.

[0031] The screen 400 of the shield nozzle 200 divides the inside of the nozzle body 300. As shown in Fig. 2, the screen 400 fits into the curved portion 328 in the expansion portion 320 of the nozzle body 300 in a state where it is curved convexly toward the base end 302. In this way, the screen 400 rectifies the shielding gas discharged from the tip 308 of the nozzle body 300 to the periphery of the electrode rod 180 so that the shielding gas becomes a laminar flow.

[0032] Fig. 4 is a cross-sectional view showing details of the screen 400. The shape of the screen 400 shown in Fig. 4 shows the state before it is attached to the nozzle body 300. The screen 400 has a disk shape formed by stacking a plurality of 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 metal meshes 410 each having a disk shape. In this embodiment, the plurality of metal meshes 410 includes five metal meshes 410a, 410b, 410c, 410d, and 410e in this order from the base end 302 side. In the description of this specification, the reference symbol "410" is used to collectively refer to each of the plurality of metal meshes in the screen 400, and a reference symbol "410" with "a, b, c, ..." is used to distinguish each of the plurality of metal meshes in the screen 400.

[0034] Each of the metal meshes 410 has a plain weave structure 415 made up of vertical lines 417 and horizontal lines 419. The vertical lines 417 and horizontal lines 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] Metal mesh 410a of screen 400 is a first metal mesh located at the end of screen 400 on the base end 302 side. Metal meshes 410b to 410e of screen 400 are a plurality of second metal meshes located closer to tip end 308 than first metal mesh 410.

[0036] In this embodiment, the mesh number of the metal mesh 410a is 40 meshes (40 meshes per inch), and the mesh number of the metal meshes 410b to 410e is 100 meshes (100 meshes per inch). In this embodiment, the outer diameter D5 of the metal mesh 410a is the same as the outer diameter D6 of the metal meshes 410b to 410e. Before the screen 400 is assembled to the nozzle body 300, the outer diameter D5 of the metal mesh 410a and the outer diameter D6 of the 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 weld 402 of the screen 400 is a weld mark formed by resistance spot welding one point at the center of a plurality of stacked metal meshes 410. In the resistance spot weld 402, adjacent metal meshes 410 are joined to each other in the plurality of metal meshes 410. As shown in FIG. 4, the resistance spot weld 402 is compressed in the thickness direction more than the non-welded portion 406 that is not resistance spot welded. A through hole 404 is formed in the center of the resistance spot weld 402. The resistance spot weld 402 forms a donut shape surrounding the through hole 404. In this embodiment, the outer diameter of the resistance spot weld 402 is about 7.0 mm.

[0038] The through hole 404 of the screen 400 is formed by punching out the center of the resistance spot welded portion 402. The through hole 404 passes through the center of the resistance spot welded portion 402. The through hole 404 is configured so that the electrode rod 180 can be fitted into the through hole 404. In this embodiment, the diameter of the through hole 404 is about 2.5 mm.

[0039] When manufacturing the screen 400, the manufacturer of the screen 400 prepares a metal mesh sheet, which is the material of the metal mesh 410. The manufacturer then heat-treats the metal mesh sheet. This causes adjacent portions 418 between vertical lines 417 and horizontal lines 419 in the metal mesh sheet to be diffusion-bonded. The worker then punches out the metal mesh sheet to produce a plurality of metal meshes 410. The manufacturer then spot-welds one point at the center of the stacked plurality of metal meshes 410 to form a resistance spot weld 402. The manufacturer then punches out the center of the plurality of metal meshes 410, which is also the center of the resistance spot weld 402, to form a through hole 404. Through these steps, the screen 400 is completed.

[0040] 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 a jig 500.

[0041] The jig 500 includes a first cylindrical portion 510, a second cylindrical portion 520, and a central axis 530. The first cylindrical portion 510 has an outer diameter that is approximately the same as the tip portion 330 of the nozzle body 300. The second cylindrical portion 520 has an outer diameter that fits loosely 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 adjacent to the first cylindrical portion 510 above and coaxially with the first cylindrical portion 510. 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 the central axis 530 of the jig 500 passes through the through-hole 404 of the screen 400 and abuts against the upper surface 522 of the second cylindrical portion 520. Thereafter, the manufacturer moves the nozzle body 300 to a position where the tip 308 abuts against the upper surface 512 of the first cylindrical portion 510. This completes the assembly of the screen 400 to the nozzle body 300 as shown in FIG. 2. The worker then removes the shield nozzle 200 from the jig 500. Through these steps, the shield nozzle 200 is completed.

[0043] 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 test of FIG. 6 and FIG. 7, the tester prepared a plurality of shield nozzles 200 with different lengths L1 and inner diameters D2 of the nozzle body 300 as samples. The length L1 and inner diameter D2 of each sample are as shown in FIG. 6 and FIG. 7. The values ​​of each part of each sample are L0=11.5mm, L2=10mm, and D1=14.8mm. The female screw 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 a 100-mesh metal mesh 410b to 410e.

[0044] The tester visualized the flow of the shielding gas discharged from the TIG welding torch 100 to which each sample was attached by Schlieren photography. The components of the TIG welding torch 100 used in the evaluation test are as follows: Head 130: Miller 1726 (USA) Back Cap 140: "57Y04" made by Miller USA Gas Lens Collet Body 160: "45V44" made by Miller, USA

[0045] The tester visually confirmed the flow of the shielding gas shown in the Schlieren photographed image. Then, the tester evaluated the rectification of the shielding gas based on the state of turbulence occurring in the evaluation range from the tip 308 of the nozzle body 300 to 20 mm in the flow of the shielding gas discharged from the shield nozzle 200.

[0046] In the test results of Figures 6 and 7, the evaluation "good" indicates that no noticeable turbulence occurred in the evaluation range of the shielding gas. The evaluation "fair" indicates that slight turbulence was confirmed in the evaluation range of the shielding gas, but the generally required welding quality was ensured. The evaluation "poor" indicates that significant turbulence was confirmed in the evaluation range of the shielding gas, and there is a possibility that the generally required welding quality cannot be ensured. According to the test results of Figures 6 and 7, from the viewpoint of ensuring the straightening of the shielding gas, it is preferable that the relationship between the length L1 and the inner diameter D2 of the nozzle body 30 satisfies L1 / D2 ≧ 0.237, and more preferably satisfies L1 / D2 ≧ 0.263.

[0047] According to the shield nozzle 200 described above, the nozzle body 300 is made of alumina crystals, which has a rough surface and smaller dimensional error during manufacturing compared to a nozzle body made of glass, so that the positional deviation of the screen 400 relative to the nozzle body 300 can be suppressed compared to a nozzle body made of glass. Also, the screen 400, which is made of a plurality of laminated metal meshes 410, fits into the curved portion 328 on the inner circumferential surface in a state of being curved convexly toward the base end 302, so that the positional deviation and deformation of the screen 400 can be suppressed. This can improve the rectification of the shield gas.

[0048] Moreover, according to the shield nozzle 200, the structure in which a plurality of metal meshes 410 are combined and the structure in which the electrode rod 180 penetrates the screen 400 can be formed by the resistance spot welds 402 and the through holes 404 of the screen 400 without using any parts other than the metal meshes 410. This allows the shield nozzle 200 to be made lighter.

[0049] Moreover, according to 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 the adjacent portions 418. This prevents the vertical lines 417 and horizontal lines 419 from coming undone, thereby further suppressing deformation of the screen 400.

[0050] Furthermore, according to the shield nozzle 200, when the female thread portion 312 has a female thread structure with a nominal diameter of 9 / 16 inch, the relationship between the length L1 and the inner diameter D2 of the nozzle body 300 preferably satisfies L1 / D2 ≧ 0.237, and more preferably satisfies L1 / D2 ≧ 0.263. This makes it possible to ensure the rectification of the shield gas while reducing the size and weight of the shield nozzle 200.

[0051] The technology disclosed in this specification is not limited to the above-mentioned embodiment, example, and modification. The technology disclosed in this specification can be realized in various configurations without departing from the spirit of the invention. Among the technical features in the above-mentioned embodiment, example, and modification, those corresponding to the technical features in each form described in the Summary of the Invention column can be replaced and combined to solve some or all of the above-mentioned problems or to achieve some or all of the above-mentioned effects. In addition, technical features that are not described as essential in this specification can be deleted as necessary.

[0052] The above-described invention 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 mesh number, number of sheets, and outer diameter of the metal mesh 410 in the screen 400 can be changed as appropriate. When the number of 40-mesh metal meshes 410 used in the screen 400 is one, from the viewpoint of rectifying the flow of the shielding gas, the number of 100-mesh metal meshes 410 is preferably five rather than three. In this case, it is preferable that the metal mesh 410a located at the end on the base end 302 side is 40 mesh, but any of the metal meshes 410 sandwiched in the center among the multiple metal meshes 410 in the screen 400 may be 40 mesh.

[0054] 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. Furthermore, before the screen 400 is assembled to the nozzle body 300, it is preferable that the outer diameter D5 of the metal mesh 410a is larger than the inner diameter D2 of the nozzle body 300 by about 1 to 2%, and the outer diameter D6 of the metal meshes 410b to 410e is smaller than the inner diameter D2 of the nozzle body 300 by about 1 to 2%. [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 thread 168…Gas lens section 180...electrode rod 200…Shield nozzle 300…Nozzle body 302...Proximal end 308…Tip 310...Proximal end 312…Female thread 320…Extension 322…adjacent area 324…Bend 326…Slope surface 328…Bend 330...Tip 332…Inner peripheral surface 400…screen 402…Resistance spot welds 404...Through hole 406…No welding 410, 400a~400e…Metal mesh 415…Plain weave structure 417…Vertical line 418…adjacent area 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 for use in a TIG welding torch to straighten a shield gas, comprising: a nozzle body made of an alumina sintered body having a cylindrical shape with a tip end expanded from a base end; A screen that is a disk-shaped laminate of multiple metal meshes and divides the inside of the nozzle body. Equipped with The nozzle body includes: A cylindrical base end portion having a female thread portion configured to be fitted to a male thread portion of a gas lens collet body of the TIG welding torch; an expansion portion that is adjacent to the base end portion and coaxially extends from a first inner diameter to a second inner diameter toward the tip end; a tip portion that is adjacent to the extended portion on the same axis as the extended portion on the tip side and has a cylindrical shape and has the second inner diameter; having the screen is fitted in a curved portion of the inner circumferential surface of the nozzle body extending from the expansion portion to the tip portion, the curved portion beginning to narrow from the second inner diameter toward the base end side, in a state where the screen is curved convexly toward the base end side, A shield nozzle, wherein the relationship between the length L1 of the extension portion and the second inner diameter D2 satisfies L1 / D2≧0.

237.

2. The shield nozzle according to claim 1, The screen comprises: a resistance spot weld portion formed by resistance spot welding the centers of the plurality of stacked metal meshes, and joining adjacent metal meshes in the plurality of metal meshes; a through hole that passes through the center of the resistance spot weld and is configured to be able to fit an electrode rod of the TIG welding torch; A shield nozzle having a

3. The shield nozzle according to claim 1, The metal mesh has a plain weave structure of vertical and horizontal lines, The vertical lines and the horizontal lines are diffusion-bonded at adjacent portions adjacent to each other.

4. The shield nozzle according to claim 1, The plurality of metal meshes include a first metal mesh located at an end of the screen on the base end side; a plurality of second metal meshes located on the front end side of the first metal mesh in the screen; Including, the first metal mesh is coarser than the second metal mesh; The outer diameter of the first metal mesh is larger than the inner diameter of the second metal mesh, The outer diameter of the second metal mesh is smaller than the second inner diameter.

5. The shield nozzle according to any one of claims 1 to 4, The female screw portion has a female screw structure with a nominal diameter of 9 / 16 inches.

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