Shield jig and gas shielded arc welding device

Abstract

To provide a shield jig which can stably guarantee gas shield performance in a wide range on a constant basis during gas shield arc welding, and to provide a gas shield arc welder.SOLUTION: A shield jig 31 includes: a first outer shell member 32A which covers a periphery of a welding torch 23, is disposed forming a radial space with the welding torch 23, and defines a first annular space S1 having a first opening 47A at a bottom part; a first gas supply member 38A which is disposed enclosing the welding torch 23 in the first outer shell member 32A and supplies a shield gas to the first annular space S1; and a dispersion member 41 which is disposed below the first gas supply member 38A of the first annular space S1 and disperses the shield gas.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a shield jig and a gas shielded arc welding apparatus. [Background technology]

[0002] Gas-shielded arc welding is known in which a shielding gas (inert gas) is supplied to a welded portion to shield the welded portion from air and prevent oxidation. A welding torch used in such gas-shielded arc welding is described in Patent Document 1, for example.

[0003] The welding torch in Patent Document 1 has a configuration in which the shielding gas passage provided in the welding torch and the control gas passage that controls the cross-sectional shape of the weld bead are each independent passages, and the above-mentioned respective passages are arranged in a vertical row at positions symmetrical in the forward and backward directions of the welding, with the welding arc at the center. According to this, Patent Document 1 states that in narrow gap welding, the cross-sectional shape and penetration of the weld bead are improved by providing a front shielding gas passage and a rear shielding gas passage and controlling the gas flow rate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 1-48678 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when gas-shielded arc welding is performed using a base material or filler metal (welding wire) made of an active metal, the affinity of the active metal with the air becomes particularly strong at high temperatures, and it is easy for the active metal to react with oxygen and nitrogen in the air to form oxides and nitrides. Therefore, the hardening and weakening of the oxide and nitride-formed parts after welding becomes significant. Therefore, when gas-shielded arc welding of active metals is performed, an after-shielding jig is generally used to prevent contact between the air and the active metal, and local gas shielding is performed near the welding torch. However, when melting a filler metal such as pure titanium or a titanium alloy for additive manufacturing, it is still difficult to suppress the intrusion of oxygen and nitrogen into the molded body to below the specified value just by using an after-shielding jig.

[0006] For example, oxygen and nitrogen attached to other materials such as air and base material are present ahead in the direction of welding, making it difficult to prevent these from being entrained. In addition, the current shielding jig has a narrow shielding range covered by shielding gas, making it difficult to ensure gas shielding of the surrounding weld bead that becomes hot adjacent to the weld bead during welding during additive manufacturing. Furthermore, depending on the direction of welding, gas shielding may be insufficient, which may limit additive manufacturing using a manipulator.

[0007] Therefore, an object of the present invention is to provide a shielding jig and a gas-shielded arc welding apparatus that can always stably ensure a wide range of gas shielding properties during gas-shielded arc welding. [Means for solving the problem]

[0008] The present invention comprises the following configurations. (1) A shield jig that is attached to a welding torch for shield welding, which melts and solidifies a metal filler metal to form a weld bead, a first shell member that covers the periphery of the welding torch and is disposed with a radial gap between the welding torch and defines a first annular space having a first opening at a bottom portion; a first gas supply member disposed inside the first outer shell member to surround the welding torch and supply a shielding gas to the first annular space; a dispersion member disposed below the first gas supply member in the first annular space and configured to disperse the shielding gas; A shielding fixture comprising: (2) A gas shielded arc welding apparatus equipped with the shield jig described in (1). Effect of the Invention

[0009] According to the present invention, a wide range of gas shielding properties can be always ensured stably during gas-shielded arc welding. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a gas-shielded arc welding device. [Diagram 2] FIG. 2 is a perspective view of a shield nozzle at the tip of a welding torch and a shield jig of a first configuration example provided on the outer periphery of the shield nozzle. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing the internal structure of the shield nozzle. [Figure 4] FIG. 4 is a schematic cross-sectional view showing the internal structure of the shielding jig of the first configuration example. [Diagram 5] FIG. 5 is an explanatory diagram that illustrates a welding torch during welding and the flow of shielding gas by the shielding jig of the first configuration example. [Figure 6] FIG. 6 is a schematic diagram of a weld bead formed using a shielding jig, where (A) is a plan view and (B) is a side view. [Figure 7] FIG. 7 is a graph showing the relationship between the oxygen content and the nitrogen content in the weld beads of the test examples shown in FIG. [Figure 8] FIG. 8 is a schematic cross-sectional view showing the internal structure of the shielding jig of the second configuration example. [Figure 9] FIG. 9 is an explanatory diagram that illustrates a welding torch during welding and the flow of shielding gas by the shielding jig of the second configuration example. [Figure 10] FIG. 10 is a perspective view showing a schematic configuration of a shielding jig of a modification in which a flow straightening portion for controlling the flow direction of the shielding gas is provided in the shielding jig of the second configuration example. [Figure 11] FIG. 11 is an explanatory diagram showing the state of shielding gas sprayed from shielding jig 31B, where (A) is a partial cross-sectional view of the bottom of the shielding jig, and (B) is a cross-sectional view of the formed gas curtain taken along line XI-XI shown in (A). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The shielding jig according to the present invention will be described here taking as an example a case in which a layered object is manufactured by gas shielded arc welding, but the present invention is not limited to this.

[0012] FIG. 1 is a schematic diagram of a gas-shielded arc welding device. The gas shielded arc welding apparatus 100, which is an apparatus for manufacturing an additive manufacturing object, includes a welding robot 11, a robot driving unit 13, a filler metal supply unit 15, a shielding gas supply unit 17, a welding power source unit 19, and a control unit 21.

[0013] The welding robot 11 is an articulated robot, and a welding torch 23 is supported on the tip shaft. The position and posture of the welding torch 23 can be set arbitrarily in three dimensions within the range of the degrees of freedom of the robot arm. The welding torch 23 holds the filler material M, which is continuously supplied from the filler material supply unit 15, in a state where it protrudes from the tip of the welding torch.

[0014] The shielding gas supply unit 17 supplies an inert gas to the welded portion. In MIG welding, argon, helium (or a mixture of these), or a gas with a small amount of an active gas such as oxygen or carbon dioxide added thereto, is used as the shielding gas. On the other hand, in MAG welding, carbon dioxide gas or a mixture of argon and carbon dioxide gas is used as the shielding gas, and in TIG welding, argon gas is used. Furthermore, in laser welding, nitrogen, argon, helium, etc. are used as the shielding gas.

[0015] Welding torch 23 is a welding torch for shield welding that melts and solidifies a metallic filler material M to form a weld bead. Specifically, welding torch 23 has a shield nozzle 25 that receives shielding gas supplied from shielding gas supply unit 17 (see FIGS. 2 to 5), and the shielding gas is supplied to the weld from shield nozzle 25. 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, and is appropriately selected depending on the additive manufacturing product to be produced.

[0016] The heat source for melting the filler material M is not limited to the above-mentioned arc. For example, other types of heat sources may be used, such as a heating method using both an arc and a laser, a heating method using plasma, or a heating method using 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 more appropriately maintained, which contributes to further improving the quality of the additive manufacturing product.

[0017] The filler metal is made of pure titanium or a titanium alloy, for example, a welding wire for welding titanium and titanium alloys (see, for example, JIS Z 3331). If the filler metal is pure titanium or a titanium alloy, appropriate welding can be performed even if the welding base metal is a titanium-based material. Note that the filler metal is not limited to the above materials, and may be other materials.

[0018] A shielding jig 31 is attached to the outer periphery of the welding torch 23. The shielding jig 31 is supplied with shielding gas from the shielding gas supply unit 17 and sprays the shielding gas toward the welded portion. The details of the shielding jig 31 will be described later.

[0019] The robot driving unit 13 receives instructions from the control unit 21 to drive each part of the welding robot 11 and controls the output of the welding power source as necessary.

[0020] The control unit 21 is configured with a computer device equipped with a CPU, memory, storage, etc., and executes a drive program prepared in advance or a drive program created under desired conditions to drive each part such as the welding robot 11. As a result, the welding torch 23 moves in accordance with the drive program, and a plurality of layers of weld beads B are laminated on the base plate 29, thereby forming a layered object with a multi-layer structure.

[0021] <First configuration example> FIG. 2 is a perspective view of shield nozzle 25 at the tip of welding torch 23 and shield jig 31 of a first configuration example provided on the outer periphery of shield nozzle 25. FIG. As described above, shielding gas supply unit 17 supplies shielding gas to both welding torch 23 and shielding jig 31. Shield nozzle 25 of welding torch 23 projects filler metal M at the nozzle tip and sprays shielding gas G0 supplied from shielding gas supply unit 17 toward the welded portion below.

[0022] FIG. 3 is a schematic cross-sectional view showing the internal structure of the shield nozzle 25. As shown in FIG. The shield nozzle 25 shown here is of a consumable electrode type. A contact tip 27 is disposed inside the shield nozzle 25, and a filler material M to which a melting current is supplied is held by the contact tip 27. The welding torch 23 holds the 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 23 by a feed mechanism (not shown) attached to a part of the welding robot 11 shown in FIG. 1. As the welding torch 23 moves, the continuously fed filler material M is melted and solidified, thereby forming a weld bead B, which is a molten solidified body of the filler material M, on the base plate 29. At this time, the shield gas G0 supplied from the shield gas supply unit 17 is sprayed from the welding torch 23 through an internal space S0 defined inside the shield nozzle 25, and gas shields the periphery of the filler material M.

[0023] 2 is connected to a first gas supply pipe 33. The tip of the first gas supply pipe 33 penetrates the upper surface of the shielding jig 31 and is inserted into the jig, and is connected to a ring-shaped first hollow pipe 35. The first hollow pipe 35 is disposed above a first annular space S1 inside the jig, and has a plurality of injection ports 35a formed at equal intervals around its entire circumference. The shielding gas G1 supplied from the first gas supply pipe 33 is injected upward from the injection ports 35a of the first hollow pipe 35, and then directed downward into the first annular space S1.

[0024] FIG. 4 is a schematic cross-sectional view showing the internal structure of the shielding jig 31 of the first configuration example. Shielding jig 31 is provided on the outer periphery of shield nozzle 25 provided at the tip of welding torch 23. Shielding jig 31 includes first outer shell member 32A, a first gas supply member 38A, and a dispersion member 41.

[0025] The first shell member 32A covers the periphery of the welding torch 23, and is disposed outside the outer circumferential surface of the welding torch 23 with a radial gap therebetween, defining a first annular space S1 having a first opening 37A at the bottom. The first shell member 32A is made of a sheet metal member having an outer circumferential surface formed into a substantially cylindrical shape. A hole is provided in the center of the upper surface of the first shell member 32A, and the shield nozzle 25 passes through this hole, and the first shell member 32A and the shield nozzle 25 are fixed together by an appropriate method such as welding, screwing, or a clamping mechanism. The material, structure, etc. of the first shell member 32A are not particularly limited.

[0026] The first gas supply member 38A includes a first gas supply pipe 33 and a first hollow pipe 35. The first gas supply pipe 33 is a straight hollow pipe that penetrates the upper surface of the first outer shell member 32A. The first hollow pipe 35 is an annular hollow pipe arranged in the first annular space S1, and has a plurality of nozzles 35a for supplying shielding gas on the upper surface. That is, the first gas supply member 38A is arranged in the first annular space S1 so as to surround at least the outer peripheral surface of the welding torch 23, and a plurality of nozzles 35a for supplying shielding gas are provided with the nozzle direction facing upward. The shielding gas that has passed through the first gas supply pipe 33 is supplied to the first hollow pipe 35, and is uniformly sprayed from the nozzles 35a of the first hollow pipe 35 to the upper side of the first hollow pipe 35 over the entire circumference. The injected shielding gas then flows downward in the first annular space S1, passes through the dispersion member 41 supported by the retaining member 42, and reaches the first opening 37A formed in the bottom surface of the first annular space S1.

[0027] The dispersion member 41 is disposed below the first gas supply member 38A in the first annular space S1, and serves to disperse the shielding gas supplied from the first gas supply member 38A in the first annular space S1. A hole is provided in the center of the dispersion member 41, and the shield nozzle 25 passes through this hole. The outer periphery of the dispersion member 41 has a circular shape that is in contact with the inner periphery of the first outer shell member 32A. The dispersion member 41 is made of a fibrous member such as glass wool or steel wool, and disperses the shielding gas inside the first annular space S1. The material of the dispersion member 41 may be a material other than those mentioned above, and is not particularly limited.

[0028] The holding member 42 has a hole in its center, and the shield nozzle 25 passes through this hole. The outer periphery of the holding member 42 has a circular shape that is in contact with the inner periphery of the first outer shell member 32A. The holding member 42 can be made of, for example, a stainless steel mesh member through which the shielding gas can pass, but the material, shape, and the like of the holding member 42 are not particularly limited. The holding member 42 may have a mesh size of, for example, 0.1 mm to 1.0 mm, preferably 0.3 mm to 0.7 mm, to provide a gas rectification function. In this case, the holding member 43 also functions as a dispersion member.

[0029] The outer periphery of the holding member 42 is fixed to the inner circumferential surface of the first outer shell member 32A by welding or the like, and the dispersion member 41 is placed or affixed to the upper surface of the holding member 42. Therefore, the holding member 42 can stably hold the dispersion member 41 in the first annular space S1.

[0030] Although not shown, the flow path of the shielding gas can be restricted by providing a shielding member (insulating tape, etc.) for the shielding gas in the holding member 42, and the release area, flow rate, etc. of the shielding gas can be easily adjusted. Note that the holding member 42 may be formed by directly joining the outer periphery of the dispersion member 41 to the inner periphery of the first outer shell member 32A, in which case the holding member 42 can be omitted.

[0031] In the shielding jig 31 configured as described above, the first hollow pipe 35 surrounding the welding torch 23 sprays the shielding gas, and the dispersion member 41 further disperses the shielding gas flowing in the first annular space S1. Therefore, with this shielding jig 31, the entire circumference of the weld can be gas-shielded more widely and evenly than with an after-shielding jig or other jig used in general welding.

[0032] In addition, the bottom of the first outer shell member 32A has a narrowed portion 45 formed in which the radial distance of the first outer shell member 32A gradually decreases along the axial direction of the welding torch 23, but it may also be configured as a straight cylinder without the narrowed portion 45.

[0033] Here, an outer circumferential diameter d0 of welding torch 23 (shield nozzle 25) and an outer circumferential diameter d1 of first outer shell member 32A have a relationship of d1>d0. In addition, when a flow velocity of the shielding gas injected from first opening 37A, which is an opening of first annular space S1, is Vout and a main valve flow velocity of the shielding gas supplied to first annular space S1 is Vin, the flow velocity Vout of the shielding gas from first opening 37A can be calculated by the following formula (1).

[0034]

number

[0035] That is, in the shielding jig 31, the main valve velocity Vin of the shielding gas, the outer circumferential diameter d0 of the welding torch 23, and the outer circumferential diameter d1 of the first outer shell member 32A are set so that the flow velocity Vout of the shielding gas injected from below the first annular space S1 is 113.17 mm / sec or more. Here, the main valve velocity Vin of the shielding gas corresponds to the gas velocity according to the gas supply pressure by the shielding gas supply unit 17.

[0036] In this way, by setting the flow velocity Vout of the shielding gas injected from the first annular space S1 to 113.17 mm / sec or more, it is possible to flow a necessary and sufficient amount of shielding gas even in the forward direction of the welding, and it is possible to effectively suppress the entrainment of air, oxygen attached to various members, nitrogen, etc., into the welded part. In addition, since the outer diameter d1 of the first outer shell member 32A is set to a predetermined size or more, it is possible to contain the welded bead, which is close to the welded bead during welding and may become hot, under the shielding gas atmosphere. Therefore, it is possible to ensure reliable gas shielding. Furthermore, by ensuring the size (radial distance) of the first outer shell member 32A, it is possible to suppress the fluctuation of the gas shielding property caused by the welding direction, and the degree of freedom of molding by the welding robot can be improved.

[0037] That is, according to this shielding jig 31, by appropriately setting the inner and outer diameters of the first outer shell member 32A according to the flow rate of the shielding gas used, a high gas shielding effect can be obtained.

[0038] The first opening 37A, which is an outlet for the shielding gas, has an annular shape similar to the cross section of the first annular space S1, so that the shielding gas G1 injected from the first opening 37A forms a cylindrical curtain. The first opening 37A has an annular shape that continues in the circumferential direction, but is not limited thereto, and may have a configuration in which multiple openings are arranged in the circumferential direction, and the shape of the first opening 37A is not particularly limited.

[0039] FIG. 5 is an explanatory diagram that shows a schematic diagram of a welding torch 23 during welding and a flow of a shielding gas by a shielding jig 31 of the first configuration example. The welding torch 23 moves to stack multiple layers of weld beads B on the base plate 29, thereby forming a multi-layered layered object W. At this time, a shielding gas G0 is sprayed from the shield nozzle 25 at the tip of the welding torch 23. The shielding jig 31 also sprays the shielding gas G1 supplied to the first annular space S1 in an annular direction toward the base plate 29 from the entire circumference of the first opening 37A.

[0040] The shielding gas G1 sprayed from the first opening 37A forms a cylindrical gas curtain. The shielding gas G1 confines the shielding gas G0 sprayed from the welding torch 23 inside the formed gas curtain, and also acts to block the inflow of air Air from the outside. This effectively isolates the weld bead B during welding from the outside air, oxygen attached to other members, nitrogen, etc., and inhibits the intrusion of impurities into the additive manufacturing object W.

[0041] Furthermore, narrowed portion 45 at the bottom of first outer shell member 32A causes the spray direction of shielding gas G2 from shielding jig 31 to approach the welding torch 23. As a result, the position where shielding gas G0 from welding torch 23 hits the welded portion and the position where shielding gas G1 from shielding jig 31 hits the welded portion become closer to each other, which is expected to enhance the retention effect of the shielding gas.

[0042] FIG. 6 is a schematic diagram of a weld bead formed using a shielding jig, where (A) is a plan view and (B) is a side view. In this test example, two types of shielding jigs were prepared, one with an outer diameter d1 of φ100 mm (Test Example 1) and one with an outer diameter d1 of φ150 mm (Test Example 2), and 3 rows x 3 layers of weld beads B were formed on a base plate 29 under the following conditions. Filler material: Titanium wire (manufactured by Daido Steel Co., Ltd.) Welding speed: 20cpm Filler metal feeding speed: 6.2mpm Shielding gas: Argon gas Shielding gas supply to welding torch: 20L / min Shielding gas supply to the shielding fixture: 50L / min Shield jig shaft length: 50mm Welding torch outer diameter: φ25mm Annular diameter of the first hollow pipe: φ80mm Holding material: Stainless steel mesh with a mesh size of 0.5 mm

[0043] The order of forming the weld beads B is shown by numbers in (B) of Fig. 6. The formation of the weld beads B was carried out by producing two samples each for Test Examples 1 and 2, for a total of four samples.

[0044] Fig. 7 is a graph showing the relationship between the oxygen content and the nitrogen content in the weld bead B of each test example shown in Fig. 6. In all test examples, the intrusion of oxygen and nitrogen was kept low, and in particular, in test example 2, the oxygen content and nitrogen content were lower than those in test example 1. This is thought to be because, when the amount of shielding gas supplied to the shielding jig was constant, the smaller the outer diameter d1, the faster the gas flow rate ejected from the shielding jig, improving the gas shielding properties and suppressing air entrainment due to arc heat.

[0045] The flow velocity of the shielding gas sprayed from first opening 37A was 48.05 mm / sec in Test Example 1, and 113.17 mm / sec in Test Example 2. If the flow velocity is equal to or higher than that in Test Example 2, the intrusion of impurities can be more reliably suppressed, and good welding can be performed.

[0046] <Second configuration example> FIG. 8 is a schematic cross-sectional view showing the internal structure of a shielding jig 31A of the second configuration example. A shielding jig 31A of this configuration includes a second outer shell member 32B and a second gas supply member 38B in addition to the configuration of the shielding jig 31 of the first configuration example.

[0047] The second shell member 32B is disposed outside the outer peripheral surface of the first shell member 32A with a radial gap therebetween, and defines a second annular space S2 between the first shell member 32A and the second shell member 32B. An upper portion of the second annular space S2 is closed by a lid portion 39, and a bottom portion of the second annular space S2 has a second opening 37B. The second shell member 32B has a cylindrical outer peripheral surface, and when the outer peripheral diameter of the welding torch 23 (shield nozzle 25) is d0, the outer peripheral diameter of the first shell member 32A is d1, and the inner peripheral diameter of the second shell member 32B is d2, d2>d1>d0 holds.

[0048] The second shell member 32B is made of a sheet metal member formed into a substantially cylindrical shape. A hole is provided in the center of the upper surface of the second shell member 32B, and the first shell member 32A is fixed to this hole. The material, structure, etc. of the second shell member 32B are not particularly limited.

[0049] The second gas supply member 38B includes a second gas supply pipe 34 and a second hollow pipe 36. The second gas supply pipe 34 is a straight hollow pipe that penetrates the upper surface of the second outer shell member 32B. The second hollow pipe 36 is an annular hollow pipe arranged in the second annular space S2, and has a plurality of nozzles 36a on the upper surface for supplying the shielding gas. That is, the second gas supply member 38B is arranged in the second annular space S2 so as to surround at least the outer peripheral surface of the first outer shell member 32A, and the plurality of nozzles 36a are provided with the shielding gas spray direction facing upward. The shielding gas that has passed through the second gas supply pipe 34 is supplied to the second hollow pipe 36, and is sprayed uniformly from the nozzles 36a of the second hollow pipe 36 to the upper side of the second hollow pipe 36 over the entire circumference. Thereafter, the injected shielding gas flows downward in the second annular space S2 and reaches the second opening 37B formed in the bottom surface of the second annular space S2.

[0050] FIG. 9 is an explanatory diagram that illustrates a schematic diagram of welding torch 23 during welding and the flow of shielding gas by shield jig 31A of the second configuration example. The welding torch 23 moves to stack multiple layers of weld beads B on the base plate 29, thereby forming a multi-layered additive object W. At this time, the shield nozzle 25 at the tip of the welding torch 23 sprays the shielding gas G0 together with the filler material M. The shield jig 31A also sprays the shielding gas G1 supplied to the first annular space S1 and the shielding gas G2 supplied to the second annular space S2 in an annular manner from the entire circumference of the first opening 37A and the second opening 37B toward the tip side of the welding torch 23.

[0051] The shielding gas G1 sprayed from the first opening 37A forms a cylindrical gas curtain. The shielding gas G1 confines the shielding gas G0 sprayed from the welding torch 23 inside the formed gas curtain, and also acts to block the inflow of air Air from the outside. This effectively isolates the weld bead B during welding from the outside air and oxygen, nitrogen, and the like attached to other members, and inhibits the intrusion of impurities into the additive manufacturing object W.

[0052] The shielding gas G2 sprayed from the second opening 37B also forms a cylindrical gas curtain. The shielding gas G2 confines the shielding gas G0 sprayed from the welding torch 23 and the shielding gas G1 sprayed from the first opening 37A inside the formed gas curtain, and also acts to block the inflow of air Air from the outside. In this case, due to the difference in the opening area of ​​the bottom, the spray speed of the shielding gas G2 is sprayed faster than the spray speed of the shielding gas G1. As a result, the outer shielding gas G2 embraces the inner shielding gas G1, forming a double gas curtain. Therefore, the synergistic effect of the shielding gases G1 and G2 can further suppress the intrusion of impurities from the outside into the layered object W.

[0053] In addition, a narrowed portion 45 is formed at the bottom of the second outer shell member 32B, in which the radial distance of the second outer shell member 32B gradually decreases along the axial direction of the welding torch 23. In association with the formation of the narrowed portion 45, a corresponding narrowed portion 46 is also formed at the bottom of the first outer shell member 32A. The radial gap between the narrowed portion 45 and the narrowed portion 46 is constant along the circumferential direction, and is set to be approximately equal to the size of the radial gap other than the bottom, which is (d2-d1) / 2. As a result, the point where the shielding gas G0, the shielding gas G1, and the shielding gas G2 collide with each other is closer to the welding torch 23, and it is expected that the retention effect of the shielding gas can be further improved. The shielding jig 31A may be formed of a straight cylindrical body without the narrowed portions 45 and 46.

[0054] In addition, the relative sizes of first outer shell member 32A and second outer shell member 32B are designed with respect to welding torch 23 so that d1-d0>d2-d1 holds when the outer diameter of welding torch 23 is d0, the outer diameter of first outer shell member 32A is d1, and the inner diameter of second outer shell member 32B is d2. This makes the radial width of first annular space S1 larger than the radial width of second annular space S2, thereby saving the amount of shielding gas.

[0055] That is, in this configuration, the supply source of the shielding gas is a single shielding gas supply unit 17 (FIG. 2), and the shielding gas supply unit 17 supplies the shielding gas to each of the welding torch 23, the first gas supply member 38A, and the second gas supply member 38B. In order to stabilize the supply of the shielding gas G0 from the welding torch 23, the shielding gas supply unit 17 controls the supply of the shielding gas to a specified constant amount. Therefore, the supply pressure of the shielding gas in the welding torch 23 is controlled to be constant. At this time, the shielding jig 31A receives the same gas supply pressure as the gas supply pressure of the welding torch 23 to inject the shielding gas G1 and the shielding gas G2, so that the smaller the cross-sectional area of ​​the second annular space S2 is, the faster the flow rate of the shielding gas G2 becomes. Therefore, it is possible to easily generate gas curtains with different flow rates on the inner and outer circumferential sides, and the gas shielding properties can be improved. In addition, the gas curtain on the outer circumferential side, which has a faster flow rate, is made thinner than the gas curtain on the inner circumferential side, which has a slower flow rate, so that the amount of gas consumed is reduced.

[0056] Furthermore, after the air in the first annular space S1 has been completely removed, the supply of the shielding gas G1 may be stopped and the shielding gas may be supplied only to the second annular space S2. In this case, the amount of shielding gas consumed may be reduced while maintaining a sufficient gas shielding effect.

[0057] <Modification> Fig. 10 is a perspective view showing a schematic configuration of a modified shielding jig 31B in which a flow straightening section 47 for controlling the flow direction of the shielding gas G2 is provided in the shielding jig 31A of the second configuration example. Fig. 10 shows only a lower portion of the second gas supply member 38B in the second outer shell member 32B.

[0058] The shielding jig 31B of the modified example is provided in the second annular space S2 inside the second outer shell member 32B with a flow straightening portion 47. The other configurations are the same as those of the shielding jig 31A described above. The flow straightening portion 47 is provided in the second annular space S2 and makes the flow of the shielding gas G2 spiral. The flow straightening portion 47 can be formed, for example, by disposing a sheet metal fin 49 between the outer surface of the first outer shell member 32A and the inner surface of the second outer shell member 32B.

[0059] The fins 49 are disposed at equal intervals along the circumferential direction to define a plurality of rows of spiral gas flow paths 51. The flow direction of the shielding gas G2 flowing through each gas flow path 51 is restricted by the fins 49, and the shielding gas G2 is ejected from the second opening 37B as a spiral gas flow. This forms an annular gas curtain that rotates in the circumferential direction.

[0060] The flow straightening portion 47 is configured by fins 49, but is not limited thereto. For example, a spiral hole or groove like a rifling may be formed on the outer circumferential surface of the first outer shell member 32A or the inner circumferential surface of the second outer shell member 32B. The flow straightening portion 47 may be configured such that a plurality of injection nozzles for injecting the shielding gas are arranged at the bottom of the second annular space S2 with the injection direction inclined in the circumferential direction.

[0061] FIG. 11 is an explanatory diagram showing the state of the shielding gas G2 sprayed from the shielding jig 31B, where (A) is a partial cross-sectional view of the bottom of the shielding jig 31B, and (B) is a cross-sectional view of the formed gas curtain taken along line XI-XI shown in (A).

[0062] As shown in FIG. 11A, the shielding gas G2 sprayed from the second opening 37B of the second annular space S2 forms a gas curtain CT that has a spiral flow due to the flow straightening section 47, and has a cross section that is a continuous circular ring shape as shown in FIG. 8B. According to the gas curtain CT having this spiral flow, the shielding gas is subjected to a rotating motion, so that the inflow of air into the welded portion can be more reliably prevented, and the gas shielding effect of the welded portion can be further improved. In addition, because the shielding gas is ejected while rotating, the entrainment of remaining air in the shielding gas piping can be prevented. Furthermore, in this case, too, after the air in the first annular space S1 has been completely removed, the supply of the shielding gas G1 can be stopped and the shielding gas can be supplied only to the second annular space S2, thereby saving the amount of shielding gas consumed.

[0063] The fumes generated during welding may be sucked in by providing a separate suction path within the gas curtain.

[0064] The shielding jigs 31, 31A, and 31B described above have a cylindrical shape centered on the welding torch 23, and therefore form an annular gas curtain centered on the welding torch 23. This provides a gas shielding effect in any moving direction of the welding torch 23, and does not restrict the trajectory of the welding torch 23. For example, compared to a before shield and an after shield that are provided according to the advancing direction of the welding torch 23, this can reduce restrictions on the moving direction of the welding torch 23, allowing welding with a high degree of freedom in construction.

[0065] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates mutual combinations of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the descriptions in the specification and well-known techniques, and these are included in the scope of the protection sought.

[0066] As described above, the present specification discloses the following: (1) A shield jig that is attached to a welding torch for shield welding, which melts and solidifies a metal filler metal to form a weld bead, a first shell member that covers the periphery of the welding torch and is disposed with a radial gap between the welding torch and defines a first annular space having a first opening at a bottom portion; a first gas supply member disposed inside the first outer shell member to surround the welding torch and supply a shielding gas to the first annular space; a dispersion member disposed below the first gas supply member in the first annular space and configured to disperse the shielding gas; A shielding fixture comprising: This shielding jig allows gas shielding over a wide area around the entire periphery of the weld.

[0067] (2) The shielding jig of claim 1, wherein when the flow velocity of the shielding gas sprayed from the first opening is Vout, the main valve flow velocity of the shielding gas supplied to the first annular space is Vin, the outer circumferential diameter of the welding torch is d0, and the outer circumferential diameter of the first outer shell member is d1, the following equation (2) is satisfied for the flow velocity Vout of the shielding gas.

[0068]

number

[0069] This shielding jig can effectively prevent impurities from being entrained in the welded portion.

[0070] (3) The shielding jig according to (1) or (2), further comprising a holding member attached to an inner circumferential surface of the first outer shell member in the first annular space and holding the dispersion member. This shielding jig can stably hold the dispersion member in the first annular space.

[0071] (4) The shielding jig according to (3), wherein the holding member is provided with a shielding member that limits the passage of the shielding gas. According to this shielding jig, by providing a shielding member on the holding member, the flow rate of the shielding gas and the position from which it is injected from the holding member can be freely adjusted.

[0072] (5) a second shell member disposed outside an outer circumferential surface of the first shell member with a radial gap therebetween, defining a second annular space between the first shell member and the second shell member, the second annular space having a lid portion at an upper portion and a second opening at a bottom portion; a second gas supply member that supplies the shielding gas to the second annular space; The shielding tool according to any one of (1) to (4), further comprising: This shielding jig can further enhance the effect of suppressing the intrusion of impurities into the welded portion.

[0073] (6) When the outer circumferential diameter of the welding torch is d0, the outer circumferential diameter of the first outer shell member is d1, and the inner circumferential diameter of the second outer shell member is d2, d1-d0>d2-d1 The shielding jig according to (5) above, wherein the following holds true: With this shielding jig, the difference in radial length between the outer periphery of the first outer shell member and the outer periphery of the welding torch is larger than the radial width of the annular space, so that the shielding gas can be sprayed to a position farther away from the welding torch than the radial width of the first annular space, thereby allowing the shielding gas to remain in the space centered on the welding torch.

[0074] (7) d0>d2-d1 The shielding jig according to (6) above, wherein the following holds true: According to this shielding jig, the radial width of the annular space is smaller than the outer diameter of the welding torch, so that the flow velocity of the shielding gas ejected from the annular space can be increased, thereby improving the gas shielding effect.

[0075] (8) The shielding jig according to any one of (5) to (7), wherein the second annular space is provided with a flow straightening section for making the flow direction of the shielding gas spiral. This shielding jig can more reliably prevent air from entering the welded portion, and can further improve the gas shielding effect of the welded portion. In addition, because the shielding gas is ejected while rotating, it is possible to prevent the entrainment of air remaining in the shielding gas piping.

[0076] (9) A shielding jig described in any one of (5) to (8), wherein a narrowed portion is formed at least at a bottom portion of the second outer shell member, in which the radial distance of the second outer shell member gradually decreases along the axial direction of the welding torch. With this shielding jig, the point where the shielding gas sprayed from the welding torch and the shielding gas sprayed from the second annular space collide with each other is brought closer to the welding torch, which is expected to improve the retention effect of the shielding gas.

[0077] (10) The shielding jig according to any one of (1) to (9), wherein the filler material is pure titanium or a titanium alloy. This shielding jig makes it possible to perform high-quality welding even on welding base materials that are susceptible to the intrusion of oxygen and nitrogen.

[0078] (11) A gas-shielded arc welding apparatus comprising the shielding jig according to any one of (1) to (10). This gas-shielded arc welding apparatus provides high gas shielding properties, enabling stable gas-shielded arc welding. [Explanation of symbols]

[0079] 11 Welding robot 13 Robot drive unit 15 Filler metal supply section 17 Shielding gas supply section 19 Welding power supply unit 21 Control section 23 Welding Torch 25 Shield Nozzle 27 Contact Tip 29 Base Plate 31, 31A, 31B Shielding fixture 32A First outer shell member 32B Second outer shell member 33 First gas supply pipe 34 Second gas supply pipe 35 First hollow pipe 36 Second hollow pipe 37A 1st opening 37B 2nd opening 38A First gas supply member 38B second gas supply member 41 Dispersion member 42 Retaining member 45 Narrowed part 47 Rectifier 49 Finn 51 Gas flow path 100 Gas shielded arc welding equipment B Weld bead G0, G1, G2 shielding gas M filler metal S0 interior space S1 First annular space S2 Second annular space W Laminated Model

Claims

1. A shield jig that is attached to a welding torch for shield welding in which a metal filler material is melted and solidified to form a weld bead, a first shell member that covers the periphery of the welding torch and is disposed with a radial gap between the welding torch and defines a first annular space having a first opening at a bottom portion; a first gas supply member disposed inside the first outer shell member to surround the welding torch and supply a shielding gas to the first annular space; a dispersion member disposed below the first gas supply member in the first annular space and configured to disperse the shielding gas; a second shell member disposed outside an outer circumferential surface of the first shell member with a radial gap therebetween, and defining a second annular space between the first shell member and the second shell member, the second annular space having a lid portion at an upper portion and a second opening at a bottom portion; a second gas supply member that supplies the shielding gas to the second annular space; Equipped with A flow straightening portion for making the flow direction of the shielding gas spiral is provided in the second annular space. Shield jig.

2. The flow velocity of the shielding gas injected from the first opening is Vout, the main valve flow velocity of the shielding gas supplied to the first annular space is Vin, and the outer circumferential diameter of the welding torch is d ０ The outer diameter of the first shell member is d １ 2. The shielding jig according to claim 1, wherein when the flow velocity Vout of the shielding gas is set as follows: [0010]

3. The shielding jig according to claim 1 or 2, further comprising a holding member attached to an inner circumferential surface of the first outer shell member in the first annular space, the holding member holding the dispersion member.

4. The shielding jig according to claim 3 , wherein the holding member is provided with a shielding member that limits the passage of the shielding gas.

5. The shielding jig according to any one of claims 1 to 4, wherein a narrowing portion is formed at least at the bottom of the second outer shell member, in which the radial distance of the second outer shell member gradually decreases along the axial direction of the welding torch.

6. The shielding jig according to any one of claims 1 to 5, wherein the filler material is pure titanium or a titanium alloy.

7. A gas shielded arc welding device comprising the shield jig according to any one of claims 1 to 6.

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