Welding shield jig and welding method

Abstract

To provide a welding shield tool and a welding method capable of guaranteeing a gas shield property with a simple structure.SOLUTION: On an outer peripheral side of a welding torch T, annular members 41, 42, 43 coaxial to the welding torch T are disposed overlapped. The respective annular members 41, 42, 43 have cylindrical parts 41a, 42a, 43a along the outer peripheral surface of the welding torch T and flange parts 41b, 42b, 43b. Between the plurality of cylindrical parts 41a, 42a, 43a, first gas passages 48, 49 extending in an axial direction are formed; annular second gas passages 45, 46 extending in a circumferential direction are formed among the plurality of flange parts 41b, 42b, 43b. The first gas passages 48, 49 and the second gas passages 45, 46 communicate with each other, and jet a shield gas G supplied for the second gas passages 45, 46 from outside to the tip end side of the welding torch T via the first gas passages 48, 49.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a shield jig used in gas shield welding and a welding method. [Background technology]

[0002] Gas-shielded arc welding is known, in which a shielding gas (inert gas) is supplied to a welding part to shield the welding part from air and prevent oxidation. A shielding jig used in such gas-shielded arc welding is described in, for example, Patent Document 1. The shielding jig in Patent Document 1 has a double annular member arranged around the outer periphery of a welding torch, an annular space formed between the double annular members, and a hollow annular pipe arranged above the annular space. The hollow pipe has multiple nozzles arranged in the circumferential direction of the annular space, and shielding gas is introduced into the hollow pipe and reaches the entire circumference of the annular space, from which it is sprayed toward the tip of the welding torch. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-023972 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the shielding jig of Patent Document 1 uses a circular hollow pipe, which requires forming multiple injection ports in the hollow pipe and arranging the hollow pipe between double circular members, resulting in a complex structure.

[0005] The present invention provides a welding shield jig and a welding method that can ensure gas shielding properties with a simple structure during gas-shielded welding (including laser welding). [Means for solving the problem]

[0006] As a means for solving the above problems, a first aspect of the present invention provides a welding torch welding system, in which a plurality of annular members coaxial with the welding torch are stacked and arranged on the outer periphery of the welding torch, each of the annular members having a cylindrical portion that follows the outer periphery of the welding torch and a flange portion that is provided at an end of the cylindrical portion on the opposite side of the torch tip in the axial direction, the plurality of cylindrical portions overlap with each other with a first gap in the radial direction, and the plurality of flange portions overlap with each other with a second gap in the axial direction, and a first gas flow path extending in the axial direction is formed in the first gap, A welding shield jig is provided in which a ring-shaped second gas flow passage extending circumferentially is formed in the second gap, the first gas flow passage and the second gas flow passage are connected to each other, and shielding gas supplied from the outside to the second gas flow passage is sprayed toward the tip side of the welding torch via the first gas flow passage. According to this configuration, a jig body is formed by stacking multiple annular members each having a flange portion, and a first gas flow passage extending in the axial direction and a second gas flow passage extending in the circumferential direction are formed between the overlapping annular members. The second gas flow passage allows shielding gas supplied from the outside to reach the entire circumferential direction. The shielding gas that flows in the second gas flow passage around the entire circumferential direction reaches the first gas flow passage, flows toward the torch tip, and is sprayed toward the tip of the welding torch. By forming a gas flow passage that allows shielding gas to reach the entire circumferential direction between the flange portions of the multiple stacked annular members, a uniform and excellent shielding effect can be obtained over a wide area despite the simple structure.

[0007] In a second aspect of the present invention, in the first aspect, the annular member includes a partition portion that separates the first gas flow path and the second gas flow path, and the partition portion is formed with a communication portion that extends from the second gas flow path side to the first gas flow path side and allows the shielding gas to flow. According to this configuration, the first gas flow path and the second gas flow path are separated by a partition, and the flow path is narrowed by a communication portion such as a groove or a hole formed in the partition, and then the shielding gas is made to flow from the second gas flow path to the first gas flow path. This ensures that the shielding gas reaches the entire circumferential direction through the second gas flow path, and the shielding gas can be sprayed evenly in the circumferential direction.

[0008] In a third aspect of the present invention, in the first or second aspect, the plurality of annular members are detachably connected to one another by a fastening member. According to this configuration, the multiple annular members are connected in a disassemblable manner, so that by disassembling the multiple annular members, it is possible to easily clean off any fumes or spatter that has adhered, thereby improving maintainability.

[0009] A fourth aspect of the present invention is any one of the first to third aspects, which includes three or more overlapping annular members, and the first gap and the first gas flow path, and the second gap and the second gas flow path are formed between adjacent pairs of the annular members, respectively. According to this configuration, by stacking three or more annular members and forming a first gas flow path and a second gas flow path between each annular member, the shielding gas is supplied in a divided manner to the flow paths in multiple layers, thereby widening the injection range (shield area) of the shielding gas.

[0010] A fifth aspect of the present invention provides a welding method using the welding shield jig according to any one of the first to fourth aspects. According to this configuration, welding can be performed with a uniform and good shielding effect using a shielding jig with a simple structure that utilizes the gaps between a plurality of annular members. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a welding shield jig and a welding method that can ensure gas shielding properties with a simple structure. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a side view of the shielding jig according to the first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of the shielding jig. [Figure 3]FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 2 is an exploded perspective view of the shielding jig. [Figure 5] FIG. 5 is an exploded perspective view seen from a different angle than FIG. 4. [Figure 6] FIG. 4 is a perspective view of a second annular member. [Figure 7] FIG. 10 is a perspective view of a third annular member. [Figure 8] FIG. 10 is a perspective view of a fourth annular member. [Figure 9] FIG. 3 is a cross-sectional view schematically showing a gas flow path of the shield jig. [Figure 10] FIG. 10 is a cross-sectional view corresponding to FIG. 9, showing a modified example of the shielding jig. [Figure 11] FIG. 10 is a perspective view showing another modified example of the shielding jig. [Figure 12] FIG. 10 is a plan view showing a modified example of the third annular member. [Figure 13] FIG. 10 is a side view of a shielding jig according to a second embodiment of the present invention. [Figure 14] FIG. 10 is a perspective view of a shielding jig according to a second embodiment. [Figure 15] FIG. 10 is an exploded perspective view of a shielding jig according to a second embodiment. [Figure 16] FIG. 4 is a cross-sectional view of a shielding jig according to a second embodiment, corresponding to FIG. 3. [Figure 17] FIG. 10 is a first explanatory diagram showing a gas flow in the shield jig of the second embodiment. [Figure 18] FIG. 10 is a second explanatory diagram showing the flow of gas in the shield jig of the second embodiment. [Figure 19] FIG. 10 is an explanatory diagram showing a modified example of the shielding jig of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 3, the shield jig 1 and welding method of the embodiment are used in, for example, a gas-shielded arc welding apparatus. The shield jig 1 and welding method of the embodiment will be described using an example of gas-shielded arc welding, but the present invention is not limited thereto.

[0014] <Welding equipment> A gas-shielded arc welding device includes a welding torch T for shielded welding, which melts and solidifies a metallic filler metal M to form a weld bead. The welding torch T holds the filler metal M, which is continuously supplied from a filler metal supply unit, protruding from the tip of the torch. The welding torch T has a shield nozzle S that receives shielding gas G supplied from a shielding gas supply unit (not shown). The shielding gas G (inert gas) is supplied from the tip of the shield nozzle S toward the weld. The shield nozzle S is cylindrical with a linear central axis CL. Hereinafter, the direction along the axis CL of the shield nozzle S will be referred to as the axial direction, the direction perpendicular to the axis CL will be referred to as the radial direction, and the direction around the axis center will be referred to as the circumferential direction. In addition, the torch tip side in the axial direction will be referred to as the bottom, and the side opposite the torch tip (base end side) will be referred to as the top.

[0015] The arc welding method may be either a consumable electrode type such as shielded metal arc welding or carbon dioxide gas arc welding, or a non-consumable electrode type such as TIG welding or plasma arc welding. For example, argon, helium, or a mixture of these is used in MIG welding, carbon dioxide or a mixture of argon and carbon dioxide is used in MAG welding, and argon gas is used in TIG welding. Also, nitrogen, argon, or helium is used as the shielding gas G in laser welding.

[0016] The heat source for melting the filler metal M is not limited to the arc described above. For example, other heat sources may be used, such as a heating method that combines an arc and a laser, a heating method that uses plasma, or a heating method that uses an electron beam or a laser. When heating with an electron beam or a laser, the amount of heat can be controlled more precisely, and the state of the weld bead can be maintained more appropriately.

[0017] The filler metal M is, for example, a welding wire made of pure titanium or a titanium alloy for welding titanium and titanium alloys (see, for example, JIS Z 3331). If the filler metal M is pure titanium or a titanium alloy, appropriate welding can be performed even if the welding base metal is a titanium-based material.

[0018] The welding torch T holds a filler material M and generates an arc from the tip of the filler material M in a shielding gas atmosphere. The filler material M is fed to the welding torch T by a feeding mechanism (not shown). As the welding torch T moves, the continuously fed filler material M is melted and solidified to form a weld bead, which is a molten solidified body of the filler material M. At this time, shielding gas G supplied from a shielding gas supply unit is sprayed from the welding torch T onto the weld area to shield the filler material M.

[0019] <Shield jig 1> A shielding jig 1 is attached to the outer periphery of the shielding nozzle S of the welding torch T so as to surround the outer periphery of the shielding nozzle S. The shielding jig 1 is detachably fixed to the shielding nozzle S using fixing bolts B2, which will be described later. Shielding gas G is supplied to the shielding jig 1 from a shielding gas supply unit, and the shielding jig 1 sprays the shielding gas G toward the weld. The shielding gas supply unit supplies the shielding gas G to both the welding torch T and the shielding jig 1. The shielding jig 1 sprays the shielding gas G on the outer periphery of the shielding nozzle S.

[0020] A gas supply pipe N1 is installed in the shielding jig 1. The downstream end of the gas supply pipe N1 penetrates the upper surface of the flange portion 11b and is inserted into the jig, and is connected to the annular upper gas flow path 15. In FIGS. 1 to 3, a single gas supply pipe N1 is provided, and supplies shielding gas G sequentially from the upstream upper gas flow path 15 to the downstream lower gas flow path 17 among the multiple layers of gas flow paths 15 to 17 in the shielding jig 1.

[0021] The gas supply configuration of the shielding jig 1 may be configured, for example, as shown in Fig. 11, such that a plurality of gas supply pipes N1 are provided for each level of the gas flow passages 15 to 17, and the shielding gas G is supplied individually to each of the gas flow passages 15 to 17. In Fig. 11, the gas supply pipe N1 is connected to the upper gas flow passage 15, and the gas supply pipe N2 is connected to the middle gas flow passage 16. Furthermore, the type of gas and the flow rate may be changed for each level.

[0022] The openings 18a, 19a in the shielding jig 1, which serve as outlets for the shielding gas G, have a circular shape that is continuous in the circumferential direction. The shielding gas G injected downward from the openings 18a, 19a forms a cylindrical gas flow (hereinafter also referred to as a gas curtain). Note that the openings 18a, 19a are not limited to having a circular shape formed along the circumferential direction. For example, the openings 18a, 19a may have a plurality of opening shapes that are divided in the circumferential direction.

[0023] Shielding gas G is sprayed in a circular pattern from openings 18a, 19a of shield jig 1 toward the weld (the tip side of welding torch T) to form a gas curtain. Shielding gas G is sprayed from shield nozzle S of welding torch T toward the inner periphery of the gas curtain. On the inner periphery of the gas curtain, the shielding gas G sprayed from shield nozzle S is confined and the inflow of air from outside is blocked. This promotes the retention of shielding gas G sprayed from welding torch T, enhances the gas shielding effect at the weld, and effectively isolates the weld bead from the outside air during welding. According to the shielding jig 1 of the embodiment, a good gas shielding effect can be obtained even with a small amount of gas due to the gas curtain of the shielding gas G and the shielding gas G supplied into the gas curtain.

[0024] The structure of the shielding jig 1 will be described in detail below. 4 and 5, the shield jig 1 is configured by stacking a plurality of annular members 11 to 14 that are coaxial with the welding torch T. Hereinafter, the annular members 11 to 14 will be referred to as the first annular member 11, the second annular member 12, the third annular member 13, and the fourth annular member 14, in that order from top to bottom in the exploded perspective views of FIGS.

[0025] The first, third, and fourth annular members 11, 13, and 14 each include a cylindrical portion 11a, 13a, and 14a that fits along the outer circumferential surface of the welding torch T, and a disk-shaped flange portion 11b, 13b, and 14b that is formed with an expanded diameter at the end of the cylindrical portion 11a, 13a, and 14a on the axial side opposite the torch tip. The second annular member 12 is formed by a flange portion 12b that is sandwiched between the flange portions 11b and 13b of the first and third annular members 11 and 13, and does not have a cylindrical portion.

[0026] Hereinafter, the cylindrical portion 11a and flange portion 11b of the first annular member 11 will be referred to as the first cylindrical portion 11a and first flange portion 11b, respectively, the flange portion 12b of the second annular member 12 will be referred to as the second flange portion 12b, the cylindrical portion 13a and flange portion 13b of the third annular member 13 will be referred to as the third cylindrical portion 13a and third flange portion 13b, respectively, and the cylindrical portion 14a and flange portion 14b of the fourth annular member 14 will be referred to as the fourth cylindrical portion 14a and fourth flange portion 14b, respectively.

[0027] There are no particular restrictions on the material of each of the annular members 11 to 14, but metal or non-ferrous metal is preferred. Each of the annular members 11 to 14 is, for example, integrally formed. The inner diameter of the first cylindrical portion 11a may be manufactured to match the outer diameter of the welding torch T, or an adapter ring that matches the outer diameter of the welding torch T may be used.

[0028] 3 and 9, the diameters of the first, third, and fourth cylindrical portions 11a, 13a, and 14a increase in this order. The first, third, and fourth cylindrical portions 11a, 13a, and 14a overlap with each other in the radial direction from the inner periphery to the outer periphery, with first gaps S21 and S22 therebetween. Hereinafter, the gap S21 between the first and third cylindrical portions 11a and 13a will be referred to as the inner periphery gap, and the gap S22 between the third and fourth cylindrical portions 13a and 14a will be referred to as the outer periphery gap.

[0029] The inner gap S21 forms a cylindrical inner gas flow path 18 (first gas flow path) extending in the axial direction. A lower end opening 18a of the inner gas flow path 18 (an opening at the lower end height of the first cylindrical portion 11a) forms an annular inner gas injection port 18a. The gap S22 on the outer periphery side forms a cylindrical outer peripheral gas flow path 19 (first gas flow path) extending in the axial direction. A lower end opening 19a of the outer peripheral gas flow path 19 (an opening at the same height as the lower end of the third cylindrical portion 13a) forms an annular outer peripheral gas injection port 19a. The first gas flow passage is not limited to a cylindrical integral flow passage that is continuous in the circumferential direction, but may be a plurality of flow passages that are divided in the circumferential direction by ribs or the like.

[0030] The lower end of the fourth cylindrical portion 14a is at the same height as the lower end of the shielding jig 1. The lower end of the third cylindrical portion 13a (and the outer peripheral gas injection port 19a) is located higher than the lower end of the fourth cylindrical portion 14a. The lower end of the first cylindrical portion 11a (and the inner peripheral gas injection port 18a) is located higher than the lower end of the third cylindrical portion 13a. As a result, at the lower end of the shielding jig 1, shielding gas G is injected from the gas injection ports 18a, 19a at different heights.

[0031] The height of each gas injection port 18a, 19a (the length of each cylindrical portion 11a, 13a, 14a) may be changed as appropriate. 10 shows an example in which the heights of the bottom ends of the cylindrical portions 11a, 13a, and 14a are the same. In this case, the shielding gas G is injected from gas injection ports 18a and 19a at the bottom end of the shielding jig 1, which are at the same height. The gaps S21, S22 between the cylindrical portions 11a, 13a, 14a are not particularly limited, but are preferably 1 to 8 mm, more preferably 1 to 6 mm, and even more preferably 1 to 4 mm.

[0032] 3 and 9, the first to fourth flange portions 11b to 14b overlap with each other with second gaps S11, S12, and S13 provided between adjacent flange portions in the axial direction. Hereinafter, the gap S11 between the first and second flange portions 11b and 12b will be referred to as the upper gap S11, the gap S12 between the second and third flange portions 12b and 13b will be referred to as the middle gap S12, and the gap S13 between the third and fourth flange portions 13b and 14b will be referred to as the lower gap S13.

[0033] The upper gap S11 forms a circumferentially extending annular upper gas flow passage 15. The upper gas flow passage 15 is connected to the downstream side of a gas supply pipe N1, and a shielding gas G is supplied from the gas supply pipe N1. The middle gap S12 forms a circumferentially extending annular middle gas flow passage 16 (second gas flow passage). The middle gas flow passage 16 is connected to the upper gas flow passage 15 via a first communication hole 12h (described later), and the shielding gas G is supplied from the upper gas flow passage 15. The lower gap S13 forms a circumferentially extending annular lower gas flow passage 17 (second gas flow passage). The lower gas flow passage 17 is connected to the middle gas flow passage 16 via second communication holes 13h (described later), and the shielding gas G is supplied from the middle gas flow passage 16.

[0034] 3 and 6, the second flange portion 12b is formed with a plurality of (a pair of in the figures) first communication holes 12h (through holes) that connect the upper-stage gas flow passage 15 and the middle-stage gas flow passage 16. The opening area of ​​the first communication holes 12h is smaller than the flow passage cross-sectional area of ​​the upper-stage gas flow passage 15. Therefore, the shielding gas G supplied to the upper-stage gas flow passage 15 is supplied to the middle-stage gas flow passage 16 from each first communication hole 12h in a state where it has spread all around the upper-stage gas flow passage 15.

[0035] 3 and 7, the third flange portion 13b is formed with a plurality of (a pair of) second communication holes 13h (through holes) that connect the middle-stage gas passage 16 and the lower-stage gas passage 17. The second through holes 13h are arranged at positions that avoid the first through holes 12h in the circumferential direction (positions that do not overlap with the first through holes 12h). The opening area of ​​the second through holes 13h is smaller than the flow passage area of ​​the middle-stage gas passage 16. Therefore, the shielding gas G supplied to the middle-stage gas passage 16 is supplied to the lower-stage gas passage 17 from each second communication hole 13h in a state where it is distributed around the entire circumference of the middle-stage gas passage 16.

[0036] The inner peripheral end of the middle-stage gas passage 16 is located on the outer peripheral side of the upper end of the inner peripheral gas passage 18. An upwardly protruding annular first upper end wall 13d (partition portion) is formed above the third cylindrical portion 13a of the third annular member 13. The first upper end wall 13d separates the inner peripheral end of the middle-stage gas passage 16 from the upper end of the inner peripheral gas passage 18. A plurality of first communication grooves 13g that open upward are formed in the first upper end wall 13d at equal intervals in the circumferential direction. Each first communication groove 13g extends radially, for example, in the radial direction. Each first communication groove 13g extends from the middle-stage gas passage 16 side (outer peripheral side) to the inner peripheral gas passage 18 side (inner peripheral side) to form a flow path for the shielding gas G.

[0037] The shielding gas G supplied to the intermediate gas flow passage 16 flows toward the inner circumference through each first communicating groove 13g, collides with the first cylindrical portion 11a, then flows downward through the inner gas flow passage 18, and is sprayed onto the weld from the lower end opening 18a of the inner gas flow passage 18.

[0038] Although each of the first communication grooves 13g extends radially along the radial direction, for example, it may extend at an angle relative to the radial direction, as in the case of a first communication groove 13g' shown in FIG. The shielding gas G that passes through each of the first communicating grooves 13g' that are inclined relative to the radial direction flows downward in a spiral flow (swirling flow) centered on the axis CL in the inner gas flow passage 18 and is then sprayed downward from the openings 18a. As a result, the shielding gas G sprayed from the openings 18a forms a gas curtain with a spiral flow. This gas curtain with a spiral flow more reliably prevents air from flowing into the weld because the rotational flow is added to the shielding gas G, further enhancing the gas shielding effect of the weld.

[0039] 3 and 8, the inner peripheral end of the lower gas passage 17 is located on the outer peripheral side of the upper end of the outer peripheral gas passage 19. An upwardly protruding annular second upper end wall 14d (partition portion) is formed above the fourth cylindrical portion 14a of the fourth annular member 14. The second upper end wall 14d separates the inner peripheral end of the lower gas passage 17 from the upper end of the outer peripheral gas passage 19. A plurality of second communication grooves 14g that open upward are formed at equal intervals in the circumferential direction in the second upper end wall 14d. Each second communication groove 14g extends radially, for example, in the radial direction. Each second communication groove 14g extends from the lower gas passage 17 side (outer peripheral side) to the outer peripheral gas passage 19 side (inner peripheral side) to form a flow path for the shielding gas G.

[0040] The shielding gas G supplied to the lower gas flow passage 17 flows toward the inner circumference through each second communicating groove 14g, collides with the third cylindrical portion 13a, then flows downward through the outer peripheral gas flow passage 19 and is sprayed onto the weld from the lower end opening 18a of the outer peripheral gas flow passage 19. Similar to the first communicating grooves 13g', each second communicating groove 14g may extend at an angle relative to the radial direction.

[0041] The upper gap S11 (upper gas flow passage 15) is formed by a first annular groove 15a formed in the lower surface of the first flange portion 11b. The middle gap S12 (middle gas flow passage 16) is formed by a second annular groove 16a formed in the lower surface of the second flange portion 12b and a third annular groove 16b formed in the upper surface of the third flange portion 13b. The second annular groove 16a is wider in the radial direction than the first annular groove 15a and the third annular groove 16b and is formed to extend more inward than the first annular groove 15a. The third annular groove 16b is formed to be biased toward the inner periphery of the second annular groove 16a.

[0042] The lower gap S13 (lower gas flow passage 17) is formed by a fourth annular groove 17a formed in the upper surface of the fourth flange portion 14b. The fourth annular groove 17a is formed at the same radial position as the first annular groove 15a. The cross-sectional area of ​​the lower gas flow passage 17 formed by the fourth annular groove 17a is smaller than the cross-sectional area of ​​the middle gas flow passage 16 formed by the second and third annular grooves 16a and 16b. A portion of the shielding gas G supplied to the middle gas flow passage 16 is supplied to the inner circumferential gas flow passage 18, and the remainder is supplied to the lower gas flow passage 17.

[0043] Seal grooves for accommodating packings 15p and 15p2 (O-rings) are formed on the outer and inner peripheral sides of the upper surface of second flange portion 12b, respectively. Seal grooves for accommodating packings 16p and 17p (O-rings) are formed on the outer peripheral sides of the upper surfaces of third flange portion 13b and fourth flange portion 14b, respectively.

[0044] An annular fixed upper end wall 11d that protrudes upward is formed above the first cylindrical portion 11a of the first annular member 11. Nut holes are formed through the fixed upper end wall 11d in a plurality of locations that are equally spaced around the circumference, extending along the radial direction. A fixing bolt B2 is screwed into each nut hole from the radial outside. By tightening each of these fixing bolts B2 and pressing the bolt tip against the outer peripheral surface of the shield nozzle S, the shield jig 1 is fixed to the outer periphery of the shield nozzle S.

[0045] The first to fourth flange portions 11b to 14b are formed with a plurality of bolt insertion holes and nut holes that are coaxially connected along the axial direction and are equally spaced apart in the circumferential direction. A fastening bolt B1 is inserted into each bolt hole from above. Each fastening bolt B1 is threaded into a nut hole formed in the fourth flange portion 14b and tightened. This fastens the first to fourth flange portions 11b to 14b together, thereby integrating the first to fourth annular members 11 to 14 to form the shield jig 1.

[0046] The shield jig 1 can be removed from the shield nozzle S and separated into a plurality of annular members 11 to 14 by releasing the fastening bolts B1. Therefore, even if fumes or spatters adhere to the members, they can be easily cleaned and can be used permanently. In the embodiment, multiple annular members 11 to 14 are joined using fastening bolts B1 and O-rings, but gaskets or Teflon (registered trademark) may be used instead of O-rings, and the annular members may be joined together by brazing instead of using fastening bolts B1.

[0047] As described above, shield jig 1 in the above embodiment has a plurality of annular members 11, 13, 14 coaxial with welding torch T that are stacked on top of each other on the outer circumferential side of welding torch T, and each annular member 11, 13, 14 has cylindrical portions 11a, 13a, 14a that follow the outer circumferential surface of welding torch T and flange portions 11b, 13b, 14b that are provided at the ends of cylindrical portions 11a, 13a, 14a on the opposite side of the torch tip in the axial direction, and the plurality of cylindrical portions 11a, 13a, 14a overlap each other with first gaps S21, S22 spaced apart in the radial direction. The multiple flange portions 11b, 13b, 14b overlap each other in the axial direction with second gaps S12, S13 between them, and first gas flow paths 18, 19 extending axially are formed in the first gaps S21, S22, and annular second gas flow paths 16, 17 extending circumferentially are formed in the second gaps S12, S13, and the first gas flow paths 18, 19 and the second gas flow paths 16, 17 are connected to each other, and shielding gas G supplied from the outside to the second gas flow paths 16, 17 is sprayed toward the tip side of the welding torch T via the first gas flow paths 18, 19.

[0048] According to this configuration, the jig body is formed by stacking multiple annular members 11, 13, and 14, each having a flange portion 11b, 13b, and 14b. First gas flow passages 18, 19 extending axially and second gas flow passages 16, 17 extending circumferentially are formed between the overlapping annular members 11, 13, and 14. The second gas flow passages 16, 17 allow shielding gas G supplied from the outside to reach the entire circumference in the circumferential direction. The shielding gas G that flows circumferentially in the second gas flow passages 16, 17 reaches the first gas flow passages 18, 19, flows toward the torch tip, and is sprayed toward the tip of the welding torch T. By forming a gas flow passage that allows shielding gas G to reach the entire circumference between the flange portions 11b, 13b, and 14b of the stacked annular members 11, 13, and 14, a uniform and excellent shielding effect can be obtained over a wide area despite the simple structure.

[0049] In the above-mentioned shielding jig 1, the annular members 13, 14 have partition portions (upper end walls 13d, 14d) that separate the first gas flow paths 18, 19 and the second gas flow paths 16, 17, and the partition portions have communicating grooves 13g, 14g that extend from the second gas flow paths 16, 17 side to the first gas flow paths 18, 19 side and allow the shielding gas G to flow. According to this configuration, the first gas flow paths 18, 19 and the second gas flow paths 16, 17 are separated by a partition, the flow path is narrowed by the communicating grooves 13g, 14g formed in the partition, and then the shielding gas G is made to flow from the second gas flow paths 16, 17 to the first gas flow paths 18, 19. This ensures that the second gas flow paths 16, 17 reliably deliver the shielding gas G to the entire circumferential direction, and the shielding gas G can be sprayed evenly in the circumferential direction. The configuration is not limited to forming grooves in the partition to allow the shielding gas G to flow, and a configuration may also be used in which holes are formed in the partition to allow the shielding gas G to flow.

[0050] In the shielding jig 1, the plurality of annular members 11, 13, 14 are detachably joined to one another by fastening members B1. According to this configuration, the multiple annular members 11, 13, and 14 are connected in a disassemblable manner, and thus maintenance can be improved by disassembling the multiple annular members 11, 13, and 14 to easily clean off any adhering fumes and spatter. That is, in a conventional configuration using a mesh to rectify the flow of the shielding gas G, clogging occurs when fumes and spatter adhere, and the mesh must be frequently replaced. In the configuration of this embodiment, even if fumes and spatter adhere to the annular members 11, 13, and 14, they can be easily cleaned, and the jig components can be used permanently.

[0051] The shielding jig 1 has three overlapping annular members 11, 13, 14, and between adjacent pairs of the annular members 11, 13, 14, first gaps S21, S22 and first gas flow paths 18, 19, and second gaps S12, S13 and second gas flow paths 16, 17 are formed, respectively. According to this configuration, by stacking three or more annular members 11, 13, 14 and forming first gas flow paths 18, 19 and second gas flow paths 16, 17 between the annular members 11, 13, 14, respectively, the shielding gas G is supplied in a divided manner to multiple layers of flow paths. This makes it possible to expand the injection range (shielding area) of the shielding gas G. By increasing the number of annular members 11, 13, 14 on the outer periphery, the shielding effect can be obtained over a wider range.

[0052] Furthermore, according to the welding method using the above-mentioned shielding jig 1, welding can be performed with a uniform and good shielding effect using the shielding jig 1, which has a simple structure that utilizes the gaps between the multiple annular members 11, 13, and 14.

[0053] Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIGS. The shielding jig 31 of this embodiment differs from the shielding jig 1 of the first embodiment in that it includes plate-shaped gaskets 45p and 46p instead of O-rings, and that an annular water-cooled jig 57 is attached to the outer periphery of the outermost cylindrical portion 43a. Other components that are the same as those of the above embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0054] 13 to 16, shielding jig 31 is configured by stacking a plurality of annular members 41, 42, and 43 coaxial with welding torch T. Hereinafter, each annular member 41, 42, and 43 will be referred to as first annular member 41, second annular member 42, and third annular member 43, in that order from top to bottom in the exploded perspective view of FIG.

[0055] Each of the first to third annular members 41 to 43 includes a cylindrical portion 41a, 42a, 43a that conforms to the outer peripheral surface of the welding torch T, and a disk-shaped flange portion 41b, 42b, 43b that is formed with an expanded diameter at the end of the cylindrical portion 41a, 42a, 43a opposite the torch tip in the axial direction.

[0056] Hereinafter, the cylindrical portion 41a and flange portion 41b of the first annular member 41 will be referred to as the first cylindrical portion 41a and first flange portion 41b, respectively, the cylindrical portion 42a and flange portion 42b of the second annular member 42 will be referred to as the second cylindrical portion 42a and second flange portion 42b, respectively, and the cylindrical portion 43a and flange portion 43b of the third annular member 43 will be referred to as the third cylindrical portion 43a and third flange portion 43b, respectively.

[0057] There are no particular restrictions on the material of each of the annular members 41 to 43, but metal or non-ferrous metal is preferred. Each of the annular members 41 to 43 is, for example, integrally formed. The inner diameter of the first cylindrical portion 41a may be manufactured to match the outer diameter of the welding torch T, or an adapter ring that matches the outer diameter of the welding torch T may be used.

[0058] The first to third cylindrical portions 41a to 43a have increasing diameters in this order. The first to third cylindrical portions 41a to 43a overlap with each other from the inner periphery to the outer periphery, with first gaps S21, S22 spaced apart in the radial direction. Hereinafter, the gap S21 between the first and second cylindrical portions 41a, 42a will be referred to as the "inner periphery gap," and the gap S22 between the second and third cylindrical portions 42a, 43a will be referred to as the "outer periphery gap."

[0059] The inner gap S21 forms a cylindrical inner gas flow passage 48 (first gas flow passage) extending in the axial direction. A lower end opening 48a of the inner gas flow passage 48 (an opening at the same height as the lower end of the first cylindrical portion 41a) forms an annular inner gas injection port 48a. The gap S22 on the outer periphery side forms a cylindrical outer peripheral gas flow passage 49 (first gas flow passage) extending in the axial direction. A lower end opening 49a of the outer peripheral gas flow passage 49 (an opening at the same height as the lower end of the third cylindrical portion 43a) forms an annular outer peripheral gas injection port 49a. The first gas flow passage is not limited to a cylindrical integral flow passage that is continuous in the circumferential direction, but may be a plurality of flow passages that are divided in the circumferential direction by ribs or the like.

[0060] The lower end of the third cylindrical portion 43a is at the same height as the lower end of the shielding jig 31. The lower end of the second cylindrical portion 42a (and the outer peripheral gas ejection port 49a) is located higher than the lower end of the third cylindrical portion 43a. The lower end of the first cylindrical portion 41a (and the inner peripheral gas ejection port 48a) is located higher than the lower end of the second cylindrical portion 42a. As a result, at the lower end of the shielding jig 31, shielding gas G is ejected from the gas ejection ports 48a, 49a, which are at different heights. The height of each gas injection port 48a, 49a (the length of each cylindrical portion 41a, 42a) may be changed as appropriate (see FIG. 10).

[0061] The first to third flange portions 41b to 43b overlap with each other with second gaps S11, S12 provided between adjacent flange portions in the axial direction. Hereinafter, the gap S11 between the first and second flange portions 41b, 42b will be referred to as the upper gap, and the gap S12 between the second and third flange portions 42b, 43b will be referred to as the lower gap. The upper gap S11 forms a circumferentially extending annular upper gas flow passage 45 (second gas flow passage). The upper gas flow passage 45 is connected to the downstream side of the first gas supply pipe N1, and the shielding gas G is supplied from the first gas supply pipe N1.

[0062] The lower gap S12 forms a circumferentially extending annular lower gas flow passage 46 (second gas flow passage). The downstream side of the second gas supply pipe N2 communicates with the lower gas flow passage 46 via a collar member C1, and the shielding gas G is supplied from the second gas supply pipe N2. That is, in the second embodiment, the shielding gas G is supplied individually to the plurality of gas flow paths 45, 46. Note that, as in the first embodiment, the shielding gas G may be supplied in order from the upstream gas flow path 45 to the downstream gas flow path 46.

[0063] The upper gas flow passage 45 is divided in the axial direction into a first upper flow passage and a second upper flow passage by a first gasket 45p that crosses the upper-lower middle portion. The first gasket 45p has a plurality of (for example, a pair of) first communication holes 45h (through holes) that communicate the first upper flow passage with the second upper flow passage. The lower-stage gas flow path 46 is partitioned in the axial direction into a first lower-stage flow path and a second lower-stage flow path by the second gasket 46 crossing the upper and lower middle part. The second gasket 46 is formed with a plurality (for example, a pair) of second communication holes 46h (through holes) that communicate between the first lower-stage flow path and the second lower-stage flow path.

[0064] 17, the inner peripheral end of the second upper-stage passage of the upper-stage gas passage 45 is located on the outer peripheral side of the upper end of the inner circumferential gas passage 48. An upwardly protruding annular first upper end wall 42d (partition portion) is formed above the second cylindrical portion 42a of the second annular member 42. The first upper end wall 42d separates the inner peripheral end of the second upper-stage passage of the upper-stage gas passage 45 from the upper end of the inner circumferential gas passage 48. A plurality of first communication grooves 42g that open upward are formed at equal intervals in the circumferential direction in the first upper end wall 42d (see first communication grooves 13g in FIG. 7). Each first communication groove 42g extends from the upper-stage gas passage 45 side (outer peripheral side) to the inner circumferential gas passage 48 side (inner peripheral side) to form a flow path for the shielding gas G.

[0065] The shielding gas G supplied to the upper gas flow passage 45 flows toward the inner circumference through each first communicating groove 42g, collides with the first cylindrical portion 41a, then flows downward through the inner gas flow passage 48, and is sprayed onto the weld from the lower end opening 48a of the inner gas flow passage 48. Each of the first communication grooves 42g extends radially along the radial direction, for example, but may extend at an angle relative to the radial direction (see first communication groove 13g' in FIG. 12).

[0066] 18, the inner peripheral end of the second lower-stage flow passage of the lower-stage gas passage 46 is located on the outer peripheral side of the upper end of the outer peripheral gas passage 49. An upwardly protruding annular second upper end wall 43d (partition portion) is formed above the third cylindrical portion 43a of the third annular member 43. The second upper end wall 43d separates the inner peripheral end of the second lower-stage flow passage of the lower-stage gas passage 46 from the upper end of the outer peripheral gas passage 49. A plurality of second communication grooves 43g that open upward are formed at equal intervals in the circumferential direction in the second upper end wall 43d (see second communication grooves 14g in FIG. 8). Each second communication groove 43g extends from the lower-stage gas passage 46 side (outer peripheral side) to the outer peripheral gas passage 49 side (inner peripheral side) to form a flow passage for the shielding gas G.

[0067] The shielding gas G supplied to the lower gas flow passage 46 flows toward the inner circumference through each second communicating groove 43g, collides with the second cylindrical portion 42a, then flows downward through the outer peripheral gas flow passage 49, and is sprayed onto the weld from the lower end opening 49a of the outer peripheral gas flow passage 49. Each second communication groove 43g extends radially along the radial direction, for example, but may extend at an angle relative to the radial direction (see first communication groove 13g' in FIG. 12).

[0068] The upper gap S11 (upper gas flow path 45) is formed by a first annular groove 45a formed in the lower surface of the first flange portion 41b and a second annular groove 45b formed in the upper surface of the second flange portion 42b. The lower gap (upper gas flow path 45) is formed by a third annular groove 46a formed in the lower surface of the second flange portion 42b and a fourth annular groove 46b formed in the upper surface of the third flange portion 43b. The annular grooves have, for example, the same radial width and the same radial position, but at least one of these may be different.

[0069] An annular fixed upper end wall 41d that protrudes upward is formed above the first cylindrical portion 41a of the first annular member 41. Nut holes are formed through the fixed upper end wall 41d at multiple locations equally spaced circumferentially along the radial direction. A fixing bolt B2 is screwed into each nut hole from the radial outside. By tightening each fixing bolt B2 and pressing the bolt tip against the outer peripheral surface of the shield nozzle S, the shield jig 31 is fixed to the outer periphery of the shield nozzle S.

[0070] The first to third flange portions 41b to 43b are formed with a plurality of bolt insertion holes and nut holes that are coaxially connected along the axial direction and are equally spaced circumferentially. A fastening bolt B1 is inserted into each bolt hole from above. Each fastening bolt B1 is threaded into a nut hole formed in the third flange portion 43b and tightened. This fastens the first to third flange portions 43b together, thereby integrating the first to third annular members 41 to 43 to form the shield jig 31.

[0071] The shield jig 31 can be removed from the shield nozzle S and separated into a plurality of annular members 41 to 43 by releasing the fastening bolts B1. Therefore, even if fumes or spatters adhere to the members, they can be easily cleaned and can be used permanently.

[0072] An annular water-cooling jig 57 is attached to the outer periphery of the third cylindrical portion 43a. The water-cooling jig 57 has an annular shape that extends downward from the third flange portion 43b. The water-cooling jig 57 has an upper surface that contacts the lower surface of the third flange portion 43b and an inner periphery that contacts the outer periphery of the third cylindrical portion 43a. In an axial cross section, the water-cooling jig 57 surrounds the corner between the third cylindrical portion 43a and the third flange portion 43b of the third annular member 43 from the outer periphery and lower side, forming a water channel 59 with a rectangular cross section. Seal grooves that accommodate packings 58p1 and 58p2 (O-rings) are formed on the upper and inner periphery of the water-cooling jig 57, respectively. A water supply and drainage pipe N5 connected to the water channel 59 is installed on the outer periphery of the water-cooling jig 57.

[0073] The tip side of the welding torch T is cooled by the water-cooling jig 57 to stabilize the temperature, thereby protecting the welding torch T and enabling stable welding. The fixing structure of the water-cooled jig 57 includes, for example, bolt insertion holes formed on the outer periphery of the water-cooled jig 57, through which fastening bolts B3 are inserted from below. Each fastening bolt B3 is threaded into a nut hole formed in the third flange portion 43b and tightened. This allows the water-cooled jig 57 to be integrally fastened to the third flange portion 43b and ultimately to the jig body.

[0074] As described above, shield jig 31 in the above embodiment has a plurality of annular members 41, 42, 43 coaxial with welding torch T that are stacked on top of each other on the outer circumferential side of welding torch T, and each annular member 41, 42, 43 has cylindrical portions 41a, 42a, 43a that follow the outer circumferential surface of welding torch T and flange portions 41b, 42b, 43b that are provided at the end of cylindrical portions 41a, 42a, 43a on the opposite side of the torch tip in the axial direction, and the plurality of cylindrical portions 41a, 42a, 43a overlap each other with first gaps S21, S22 spaced apart in the radial direction. The multiple flange portions 41b, 42b, 43b overlap each other in the axial direction with second gaps S11, S12 between them, and first gas flow paths 48, 49 extending axially are formed in the first gaps S21, S22, and annular second gas flow paths 45, 46 extending circumferentially are formed in the second gaps S11, S12, and the first gas flow paths 48, 49 and the second gas flow paths 45, 46 are connected to each other, and shielding gas G supplied from the outside to the second gas flow paths 45, 46 is sprayed toward the tip side of the welding torch T via the first gas flow paths 48, 49. According to this configuration, the jig body is formed by stacking multiple annular members 41, 42, 43, each having a flange portion 41b, 42b, 43b. Between the overlapping annular members 41, 42, 43, first gas flow passages 48, 49 extending in the axial direction and second gas flow passages 45, 46 extending in the circumferential direction are formed. The second gas flow passages 45, 46 allow the shielding gas G supplied from the outside to reach the entire circumferential direction. The shielding gas G that flows throughout the entire circumferential direction in the second gas flow passages 45, 46 reaches the first gas flow passages 48, 49, flows toward the torch tip, and is sprayed toward the tip of the welding torch T. By forming the gas flow passages that allow the shielding gas G to reach the entire circumferential direction between the flange portions 41b, 42b, 43b of the stacked annular members 41, 42, 43, a uniform and excellent shielding effect can be obtained over a wide area despite the simple structure.

[0075] In the above-mentioned shielding jig 31, the annular members 42, 43 have partition portions (upper end walls 42d, 43d) that separate the first gas flow paths 48, 49 and the second gas flow paths 45, 46, and the partition portions have communicating grooves 42g, 43g that extend from the second gas flow paths 45, 46 side to the first gas flow paths 48, 49 side and allow the shielding gas G to flow. According to this configuration, the first gas flow paths 48, 49 and the second gas flow paths 45, 46 are separated by a partition, the flow paths are narrowed by the communicating grooves 42g, 43g formed in the partition, and then the shielding gas G is caused to flow from the second gas flow paths 45, 46 to the first gas flow paths 48, 49, thereby ensuring that the shielding gas G reaches the entire circumferential direction through the second gas flow paths 45, 46 and can be sprayed evenly in the circumferential direction. The configuration is not limited to forming grooves in the partition to allow the shielding gas G to flow, and holes may be formed in the partition to allow the shielding gas G to flow.

[0076] In the shielding jig 31, the plurality of annular members 41 to 43 are detachably joined to one another by fastening members B1. According to this configuration, the multiple annular members 41-43 are joined in a disassemblable manner, and thus, by disassembling the multiple annular members 41-43, adhering fumes and spatter can be easily cleaned, thereby improving maintainability. That is, in a conventional configuration in which a mesh is used to rectify the flow of the shielding gas G, clogging occurs when fumes and spatter adhere, and the mesh must be frequently replaced. In the configuration of this embodiment, even if fumes and spatter adhere to the annular members 41-43, they can be easily cleaned, and the jig components can be used permanently.

[0077] The shielding jig 31 has three or more overlapping annular members 41 to 43, and between adjacent pairs of the annular members 41 to 43, first gaps S21, S22 and first gas flow paths 48, 49, and second gaps S11, S12 and second gas flow paths 45, 46 are formed, respectively. According to this configuration, by stacking three or more annular members 41-43 and forming first gas flow paths 48, 49 and second gas flow paths 45, 46 between the annular members 41-43, the shielding gas G is supplied in separate layers of flow paths, thereby expanding the spray range (shielding area) of the shielding gas G. By increasing the number of annular members 41-43 on the outer periphery, the shielding effect can be obtained over a wider range.

[0078] Furthermore, according to the welding method using the above-mentioned shielding jig 31, welding can be performed with a uniform and good shielding effect using the shielding jig 31, which has a simple structure that utilizes the gaps between the multiple annular members 41 to 43.

[0079] The configurations in the above-described embodiments are merely examples of the present invention, and various modifications are possible without departing from the spirit of the present invention, such as replacing the components of the embodiments with well-known components. FIG. 19 shows a modified example of the shielding jig 31 of the second embodiment. As shown in FIG. 19, a constricted portion S1 may be formed at the tip of the shield nozzle S so that the diameter decreases toward the tip. A gas rectifying unit R1 made of mesh, metal foam, sintered alloy, or the like may be provided on the outlet side of the gas flow path. In the figure, a gas rectifying unit R1 is provided in each of the annular first gas flow paths 48, 49 extending in the axial direction. The gas rectifying unit R1 is, for example, a disk-shaped member extending along the annular gas flow path. A gas rectifying unit R1 with a different diameter may be provided in each of the multiple gas flow paths, or a gas rectifying unit R1 may be provided in only one of the gas flow paths. In other words, a gas rectifying unit R1 may be provided in at least one of the multiple gas flow paths. The above-described throttle portion S1 and gas rectifying portion R1 may be applied to the shielding jig 1 of the first embodiment. [Explanation of symbols]

[0080] 1 Shield jig 11 First annular member (annular member) 11a Cylindrical part 11b Flange part 13 Third annular member (annular member) 13a Cylindrical part 13b Flange 13d top wall 13g communication groove 14 Fourth annular member (annular member) 14a Cylindrical part 14b Flange part 14d Top wall 14g communication groove 16 Middle gas flow path (second gas flow path) 17 Lower gas flow path (second gas flow path) 18 Inner gas flow path (first gas flow path) 19 Peripheral gas flow path (first gas flow path) 31 Shield jig 41 First annular member (annular member) 41a Cylindrical part 41b Flange part 42 Second annular member (annular member) 42a Cylindrical part 42b flange 42d Top wall 42g communication groove 43 Third annular member (annular member) 43a Cylindrical part 43b Flange part 43d Top wall 43g communication groove 45 Upper gas flow path (second gas flow path) 46 Lower gas flow path (second gas flow path) 48 Inner gas flow path (first gas flow path) 49 Peripheral gas flow path (first gas flow path) B1 Fastening bolt (fastening member) G Shielding gas S11, S12, S13 Second gap S21, S22 First gap T welding torch

Claims

1. A plurality of annular members coaxial with the welding torch are stacked and arranged on the outer periphery of the welding torch, Each of the annular members has a cylindrical portion that follows the outer peripheral surface of the welding torch, and a flange portion that is provided at an end of the cylindrical portion on the opposite side of the torch tip in the axial direction, The plurality of cylindrical portions overlap each other with a first gap therebetween in the radial direction, The plurality of flange portions overlap each other with a second gap in the axial direction, a first gas flow passage extending in the axial direction is formed in the first gap, a second annular gas flow passage extending in a circumferential direction is formed in the second gap, The first gas flow path and the second gas flow path are connected to each other, and a shielding gas supplied from the outside to the second gas flow path is sprayed toward the tip side of the welding torch via the first gas flow path.

2. the annular member includes a partition portion that separates the first gas flow path and the second gas flow path, The welding shield jig according to claim 1 , wherein the partition portion is formed with a communication portion extending from the second gas flow passage side to the first gas flow passage side to allow the shielding gas to flow.

3. The welding shield jig according to claim 1 or 2, wherein the plurality of annular members are detachably connected to one another by fastening members.

4. three or more of the annular members overlapping one another, 3. The welding shield jig according to claim 1, wherein the first gap and the first gas flow path, and the second gap and the second gas flow path are formed between a pair of adjacent annular members, respectively.

5. A welding method using the welding shield jig according to claim 1 or 2.

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