A device and method for high efficiency TIG welding of large thickness titanium alloy narrow gap

Abstract

The application provides a device and method for large-thickness titanium alloy narrow-gap efficient TIG welding, comprising: an insulating plate, a wire feeding device and a tungsten electrode welding gun are arranged on the insulating plate, the wire feeding device comprises a wire feeding nozzle capable of moving in three-dimensional space, and is used for feeding welding wire to the tungsten electrode welding gun, a lower part of the tungsten electrode welding gun is provided with a tungsten electrode, a lower part of the tungsten electrode is provided with a blind hole, and an insulating ceramic rod is arranged in the blind hole; a three-axis slide rail, the insulating plate is installed on the three-axis slide rail, so that the tungsten electrode welding gun can move relative to a test plate; a welding power supply, which is connected with the tungsten electrode welding gun and is used for supplying power to the tungsten electrode welding gun; and a controller, which controls working states of the wire feeding device, the welding power supply and the three-axis slide rail according to set parameters, and performs welding on the test plate. The application reduces the processing difficulty and production cost of the tungsten electrode, improves the welding deposition rate and welding efficiency, realizes good fusion of the narrow-gap two-side walls, and realizes insulation between the blind hole and the welding wire.

Description

Technical Field

[0001] This invention relates to the field of TIG welding technology, and more specifically, to an apparatus and method for efficient TIG welding of thick titanium alloys with narrow gaps. Background Technology

[0002] Non-consumable electrode tungsten inert gas (TIG) welding has advantages such as high welding quality, less spatter, low cost, and stable joint performance, and occupies a very important position in the field of titanium alloy welding technology. However, traditional narrow-gap TIG welding technology for titanium alloys has problems such as low welding deposition rate, low welding efficiency, and easy generation of incomplete fusion defects on both sides of the narrow gap, which limits its development in the field of welding thick titanium alloys.

[0003] The invention patent with application number 202010546106.7 discloses a narrow gap TIG welding device. By using a machining method to drill a hole in the center of a conventional tungsten electrode, the arc expansion pattern is controlled by controlling the gas flow rate in the tungsten electrode hole. This solves the problems of small heating area and insufficient melting of the narrow gap sidewall during welding. However, it has problems such as difficulty in machining the tungsten electrode and lack of insulation treatment between the hollow tungsten electrode tube and the welding wire, which increases the difficulty of implementing the welding process. Summary of the Invention

[0004] In view of this, the present invention aims to provide an apparatus and method for efficient TIG welding of thick titanium alloys with narrow gaps, solving the problems of low welding deposition rate, low welding efficiency, easy generation of incomplete fusion defects on both sides of the narrow gap sidewalls in the prior art of narrow gap TIG welding of titanium alloys, difficult machining of tungsten electrode hollow tubes, high production costs, and lack of insulation treatment between tungsten electrode hollow tubes and welding wire.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0006] An apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps, comprising:

[0007] An insulating board is provided with a wire feeding device and a tungsten inert gas (TIG) welding torch. The wire feeding device includes a wire feeding nozzle that can move in three-dimensional space for feeding welding wire during welding. A tungsten electrode is installed at the lower part of the TIG welding torch, and a blind hole is provided at the lower part of the tungsten electrode. An insulating ceramic rod is placed in the blind hole.

[0008] The insulating plate is mounted on the three-axis slide, which allows the tungsten inert welding torch to move relative to the test plate.

[0009] Welding power source, connected to the tungsten inert gas (TIG) welding torch, used to supply power to the TIG welding torch;

[0010] The controller controls the working status of the wire feeding device, welding power supply and triaxial carriage according to the set parameters to weld the test plate.

[0011] The device for high-efficiency TIG welding of thick titanium alloys with narrow gaps, as described in this invention, significantly reduces the processing difficulty and production cost of the tungsten electrode 31, greatly improves the welding deposition rate and welding efficiency, achieves good fusion of the sidewalls on both sides of the narrow gap, and achieves insulation between the blind hole 32 and the welding wire 22.

[0012] Furthermore, the tungsten electrode includes a first tungsten electrode and a second tungsten electrode. The first tungsten electrode has a first blind hole with a diameter of d1, where 1.5 mm ≥ d1 ≥ 1.0 mm, and the wall thickness at the lower end of the first blind hole is h1, where 0.8 mm ≥ h1 ≥ 0.3 mm. The second tungsten electrode has a second blind hole with a diameter of d2, where 3 mm ≥ d2 ≥ 1.5 mm, and the wall thickness at the lower end of the second blind hole is h2, where 0.6 mm ≥ h2 ≥ 0.3 mm.

[0013] This setup enables fusion of narrow-gap sidewalls and provides good arc stiffness when the current is high, making it suitable for welding filler.

[0014] Furthermore, the diameter of the tungsten electrode is D, 8.0mm≥D≥5.0mm, and the lower end of the tungsten electrode is set as a conical surface with an angle B, 60°≥B≥40°.

[0015] This design reduces the size of the tungsten electrode, has a simple overall structure, and can be inserted into narrow or deep narrow gaps for welding, making it widely applicable.

[0016] Furthermore, the distance between the lower end of the tungsten electrode and the test plate is 5.0 mm to 9.0 mm.

[0017] This setup can improve welding quality.

[0018] Furthermore, the tungsten inert gas (TIG) welding torch is equipped with a circulating water pipe and a gas pipe. The circulating water pipe is connected to a circulating water tank via a pipeline and is used to cool the TIG welding torch during the welding process. The gas pipe is connected to a first protective gas cylinder via a pipeline and is used to spray protective gas onto the welding area on the test plate during the welding process.

[0019] This setup can cool the tungsten inert gas torch during the welding process and provide gas protection for the welding area, thereby improving welding quality.

[0020] Furthermore, it also includes a protective device, which is installed at the bottom of the test plate. The protective device includes a gas protection tank and a cooling tank. The gas protection tank is connected to a second protective gas tank through a pipeline and is used to provide gas protection to the bottom of the test plate during the welding process. The cooling tank is connected to a cooling water tank through a pipeline and is used to cool the bottom of the test plate during the welding process.

[0021] This setup allows for cooling of the test plate during welding and provides gas protection to the welding area, thereby improving welding quality.

[0022] Furthermore, the test plate includes a first test plate and a second test plate, and a U-shaped bevel is provided on the test plate. The bottom width of the U-shaped bevel is N1, N1≥8mm, and the top width is N2, N2≤15mm.

[0023] This setup facilitates welding operations and improves welding efficiency and quality.

[0024] Furthermore, the distance between the first test plate and the second test plate is L1, and the misalignment is L2, where 0.2mm≥L1 and 0.5mm≥L2, and the misalignment refers to the height difference between the first test plate and the second test plate.

[0025] This setup facilitates welding operations and improves welding quality.

[0026] The present invention also provides a method using the above-described high-efficiency TIG welding apparatus for thick titanium alloys with narrow gaps, comprising the following steps:

[0027] Step 1: Mechanically clean the surface and U-shaped groove of the test plate to be welded, then wipe it clean with acetone, place the test plate on the protective device, teach the trajectory of the tungsten inert welding torch, set the welding parameters in the controller, and start the protective device.

[0028] Step 2: Perform root pass welding on the test plate. Replace the first tungsten electrode and adjust the distance between the first tungsten electrode and the test plate. Set the current range to 220A~300A, the welding speed to 110mm / min~150mm / min, the shielding gas flow rate to 15L / min~25L / min, and the wire feed speed to 250mm / min~500mm / min. After the root pass welding of the test plate is completed, proceed to Step 3.

[0029] Step 3: Perform welding filler on the test plate. Replace the second tungsten electrode and adjust the distance between the second tungsten electrode and the test plate. When performing the first layer of welding filler, set the current to 420A~500A, the welding speed to 110mm / min~130mm / min, the shielding gas flow rate to 20L / min~30L / min, and the wire feed speed to 1500mm / min~1800mm / min. When performing the remaining layers of welding filler, set the current to 500A~650A, the welding speed to 80mm / min~110mm / min, the shielding gas flow rate to 20L / min~30L / min, the wire feed speed to 1800mm / min~2500mm / min, the pulse frequency to 50Hz~80Hz, and the duty cycle to 80%. Alternately weld filler on the upper and lower sides of the test plate. Stop when the filler reaches 2~3mm from the upper surface of the test plate and proceed to step 4.

[0030] Step 4: Perform welding cover operation on the test plate, using a second tungsten electrode, with the pulse frequency set to 2Hz~10Hz, duty cycle set to 60%~80%, current set to 360A~450A, welding speed set to 110~150mm / min, wire feed speed set to 1300~2000mm / min, and shielding gas flow rate set to 25L / min~35L / min.

[0031] This welding method can significantly improve the welding cladding rate and welding efficiency, achieving good fusion of the sidewalls.

[0032] Furthermore, in step 3, during the first layer of welding filler, the wire feed speed is set to 1300mm / min~1600mm / min. For subsequent filler layers, the current decreases sequentially, by 15A~20A per layer. After welding filler four layers, the current is set to 480A~560A. The shielding gas is a helium-argon mixture with a helium-argon ratio of 7:3 and a gas flow rate of 20L / min~30L / min.

[0033] This setup can significantly improve the stability of the molten pool flow and the stability of the electric arc.

[0034] Compared with existing technologies, the apparatus and method for high-efficiency TIG welding of thick titanium alloys with narrow gaps described in this invention have the following advantages:

[0035] 1) Significantly reduced the processing difficulty and production cost of tungsten electrodes, and achieved insulation between blind holes and welding wire;

[0036] 2) It achieves good fusion of the sidewalls on both sides of the narrow gap, which greatly improves the welding cladding rate and welding efficiency. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the high-efficiency TIG welding device for thick titanium alloys with narrow gaps, as described in an embodiment of the present invention.

[0038] Figure 2 for Figure 1 Schematic diagram of the middle insulating plate, tungsten inert welding torch and wire feeding device;

[0039] Figure 3 for Figure 1 Schematic diagram of the pilot plate, tungsten electrode, and protection device;

[0040] Figure 4 for Figure 3 A magnified schematic diagram of the local structure at point A;

[0041] Figure 5 for Figure 1 Schematic diagram of the tungsten electrode structure;

[0042] Figure 6 This is a schematic diagram of the structure of the first tungsten electrode in an embodiment of the present invention;

[0043] Figure 7 for Figure 6 A structural diagram from another perspective;

[0044] Figure 8 This is a schematic diagram of the structure of the second tungsten electrode in an embodiment of the present invention;

[0045] Figure 9 for Figure 8 A structural diagram from another perspective.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1. Insulating board; 2. Wire feeding device; 21. Wire feeding nozzle; 22. Welding wire; 23. Wire feeding box; 3. Tungsten inert gas (TIG) welding torch; 31. Tungsten electrode; 32. Blind hole; 33. Fastening bolt; 311. First Tungsten electrode; 3110. First blind hole; 312. Second Tungsten electrode; 3120. Second blind hole; 4. Three-axis slide; 5. Welding power source; 61. Circulating water tank; 62. Cooling water tank; 71. First protective gas cylinder; 72. Second protective gas cylinder; 8. Protective device; 81. Gas protection tank; 82. Cooling tank; 9. Protective cover; 100. Test plate; 101. First test plate; 102. Second test plate; 103. U-shaped bevel. Detailed Implementation

[0048] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0049] Example 1

[0050] like Figures 1-9As shown, an apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps includes:

[0051] An insulating plate 1 is provided with a wire feeding device 2 and a tungsten inert gas (TIG) welding torch 3. The wire feeding device 2 includes a wire feeding nozzle 21 that can move in three-dimensional space for feeding welding wire 22 during welding. A tungsten electrode 31 is installed at the lower part of the TIG welding torch 3. A blind hole 32 is provided at the lower part of the tungsten electrode 31, and an insulating ceramic rod is provided in the blind hole 32.

[0052] The three-axis slide 4, the insulating plate 1 is mounted on the three-axis slide 4, so that the tungsten inert welding torch 3 can move relative to the test plate 100;

[0053] Welding power source 5 is connected to tungsten inert gas (TIG) welding torch 3 and is used to supply power to TIG welding torch 3.

[0054] The controller controls the working status of the wire feeding device 2, the welding power supply 5 and the three-axis slide 4 according to the set parameters, and performs welding on the test plate 100.

[0055] The device for high-efficiency TIG welding of thick titanium alloys with narrow gaps, as described in this invention, shortens the length of the hollow part inside the tungsten electrode 31 by setting a blind hole 32 at the lower part of the tungsten electrode 31, which greatly reduces the processing difficulty and production cost of the tungsten electrode 31, and can obtain an "M"-shaped arc, which greatly improves the welding deposition rate and welding efficiency, and achieves good fusion of the side walls on both sides of the narrow gap. By setting an insulating ceramic rod inside the blind hole 32, insulation between the blind hole 32 and the welding wire 22 is achieved.

[0056] Preferably, the length of the ceramic insulating rod is equal to the length of the blind hole 32.

[0057] Preferably, a fastening bolt 33 is provided on the tungsten electrode welding torch 3 for fixing and removing the tungsten electrode 31.

[0058] As a preferred example of the present invention, the tungsten electrode 31 includes a first tungsten electrode 311 and a second tungsten electrode 312. The first tungsten electrode 311 is provided with a first blind hole 3110, the diameter of the first blind hole 3110 is d1, 1.5mm≥d1≥1.0mm, and the wall thickness of the lower end of the first blind hole 3110 is h1, 0.8mm≥h1≥0.3mm. The second tungsten electrode 312 is provided with a second blind hole 3120, the diameter of the second blind hole 3120 is d2, 3mm≥d2≥1.5mm, and the wall thickness of the lower end of the second blind hole 3120 is h2, 0.6mm≥h2≥0.3mm.

[0059] Specifically, the structure of the first tungsten electrode 311 produces an arc with high stiffness and good directionality, making it suitable for root pass welding. The structure of the second tungsten electrode 312 produces a welding arc that diverges, forming a rotationally symmetrical "M"-shaped arc with a wide high-density arc area. This configuration enables fusion of narrow gap sidewalls and provides good arc stiffness when the current is large, making it suitable for filler welding.

[0060] As a preferred example of the present invention, the diameter of the tungsten electrode 31 is D, 8.0mm≥D≥5.0mm, and the lower end of the tungsten electrode 31 is set as a conical surface with an angle B, 60°≥B≥40°.

[0061] Specifically, this design reduces the size of the tungsten electrode 31, has a simple overall structure, and can be inserted into narrow or deep narrow gaps for welding, making it widely applicable.

[0062] As a preferred example of the present invention, the distance between the lower end of the tungsten electrode 31 and the test plate 100 is 5.0 mm to 9.0 mm.

[0063] Specifically, this setup can improve welding quality.

[0064] Preferably, the angle between the tungsten electrode 31 and the vertical axis is 0° to 15°.

[0065] As a preferred example of the present invention, the tungsten inert gas (TIG) welding torch 3 is provided with a circulating water pipe and a gas pipe. The circulating water pipe is connected to the circulating water tank 61 through a pipeline and is used to cool the TIG welding torch 3 during the welding process. The gas pipe is connected to the first protective gas tank 71 through a pipeline and is used to spray protective gas onto the welding area on the test plate 100 during the welding process.

[0066] Specifically, the first protective gas tank 71 contains argon gas. This setting can cool the tungsten inert gas torch 3 during the welding process and provide gas protection for the welding area, thereby improving the welding quality.

[0067] As a preferred example of the present invention, a protective device 8 is also included. The protective device 8 is disposed at the lower part of the test plate 100. The protective device 8 includes a gas protection tank 81 and a cooling tank 82. The gas protection tank 81 is connected to a second protective gas tank 72 through a pipeline and is used to provide gas protection to the lower part of the test plate 100 during the welding process. The cooling tank 82 is connected to a cooling water tank 62 through a pipeline and is used to cool the lower part of the test plate 100 during the welding process.

[0068] Specifically, the second protective gas tank 72 contains argon gas. This setup can cool the test plate 100 during the welding process and provide gas protection for the welding area, thereby improving the welding quality.

[0069] Preferably, the gas protection tank 81 is provided with a jet hole for jetting argon gas.

[0070] As a preferred example of the present invention, the test plate 100 includes a first test plate 101 and a second test plate 102. A U-shaped bevel 103 is provided on the test plate 100. The bottom width of the U-shaped bevel 103 is N1, N1≥8mm, and the top width is N2, N2≤15mm.

[0071] Specifically, this setup facilitates welding operations and improves welding efficiency and quality.

[0072] Preferably, the bottom and sidewall of the test plate 100 are connected by a circular arc with a radius of 3mm.

[0073] As a preferred example of the present invention, a protective cover 9 is also included, which is disposed in the welding area of ​​the test plate 100 to protect the welding area from interference from the external environment.

[0074] Specifically, this setup can further enhance the protection of the welding area and prevent the welding area from being affected by the external environment.

[0075] As a preferred example of the present invention, the wire feeding device 2 further includes a wire feeding box 23 for storing welding wire 22.

[0076] Specifically, this setup facilitates automated welding and improves welding efficiency.

[0077] As a preferred example of the present invention, the distance between the first test plate 101 and the second test plate 102 is L1, and the misalignment is L2, where 0.2mm≥L1 and 0.5mm≥L2, and the misalignment refers to the height difference between the first test plate 101 and the second test plate 102.

[0078] Specifically, this setup facilitates welding operations and improves welding quality.

[0079] The present invention also provides a method using the above-described high-efficiency TIG welding apparatus for thick titanium alloys with narrow gaps, comprising the following steps:

[0080] Step 1: Mechanically clean the surface of the test plate 100 and the U-shaped groove 103, then wipe it clean with acetone, place the test plate 100 on the protective device 8, teach the trajectory of the tungsten inert welding torch 3, set the welding parameters in the controller, and start the protective device 8.

[0081] Step 2: Perform root pass welding on test plate 100. Replace the first tungsten electrode 311, adjust the distance between the first tungsten electrode 311 and test plate 100, set the current range to 220A~300A, the welding speed to 110mm / min~150mm / min, the shielding gas flow rate to 15L / min~25L / min, and the wire feed speed to 250mm / min~500mm / min. After the root pass welding of test plate 100 is completed, proceed to step 3.

[0082] Step 3: Perform welding filler on the test plate 100. Replace the second tungsten electrode 312 and adjust the distance between the second tungsten electrode 312 and the test plate 100. When performing the first layer of welding filler, set the current to 420A~500A, the welding speed to 110mm / min~130mm / min, the shielding gas flow rate to 20L / min~30L / min, and the wire feed speed to 1500mm / min~1800mm / min. When performing the remaining layers of welding filler, set the current to 500A~650A, the welding speed to 80mm / min~110mm / min, the shielding gas flow rate to 20L / min~30L / min, the wire feed speed to 1800mm / min~2500mm / min, the pulse frequency to 50Hz~80Hz, and the duty cycle to 80%. Alternately weld filler on the upper and lower sides of the test plate 100. Stop when the filler reaches 2~3mm from the upper surface of the test plate 100 and proceed to step 4.

[0083] Step 4: Perform welding cover operation on test plate 100, using a second tungsten electrode 312, with the pulse frequency set to 2Hz~10Hz, duty cycle set to 60%~80%, current set to 360A~450A, welding speed set to 110~150mm / min, wire feed speed set to 1300~2000mm / min, and shielding gas flow rate set to 25L / min~35L / min.

[0084] Specifically, by adjusting the welding parameters and the distance between the tungsten electrode 31 and the test plate 100, the "M"-shaped arc can be adjusted so that the two legs of the arc are located on the two side walls, enhancing the fusion effect of the side walls on both sides of the narrow gap. Moreover, the energy in the middle of the "M"-shaped arc is high, and the overall welding current is large, which further improves the welding deposition rate and welding efficiency. During the welding filling process, the test plate 100 is cooled by adding high-frequency pulses, which can effectively control the interlayer temperature, inhibit grain growth to a certain extent, and improve the mechanical properties of the welded joint. When welding the capping surface, low-frequency pulses are used to obtain a high-quality silver-white fish scale textured surface. This welding method can significantly improve the welding deposition rate and welding efficiency, achieve good fusion of the side walls, and is suitable for high-efficiency TIG welding of narrow gaps in 30mm to 60mm thick titanium alloys.

[0085] Preferably, in step 1, the tungsten inert welding torch 3 is rotated to the flat welding position, and after adjustment, the test plate 100 is arranged along the welding axis.

[0086] Preferably, in step 2, the water flow rate of the cooling tank 82 is 25 L / min, and the gas flow rate of the gas protection tank 81 is 25 L / min.

[0087] Preferably, in step 2, the shielding gas is supplied before welding, and the gas is cut off after a 10-second delay after welding is completed. When welding starts, the welding wire 22 is fed for a 10-second delay, and the feeding of the welding wire is stopped after the arc is cut off.

[0088] Preferably, in step 2, a coiled wire with a diameter of 2.0 mm is used.

[0089] Preferably, in step 3, the interpass temperature is controlled to be below 200°C during the welding process.

[0090] Preferably, the protective gas is 99.99% argon.

[0091] Using the welding method of this embodiment, the base material and the weld are smoothly transitioned after welding. The weld surface has a silvery-white fish scale pattern. There are no defects such as cracks, lack of fusion, or porosity inside the weld. The tensile strength of the joint reaches 93% of that of the base material. The impact and bending performance are also greatly improved. No obvious defects were found in QT and RT tests. The weld quality meets the Class I requirements of NB / T47013.2-2015 standard.

[0092] Traditional single-TIG narrow-gap welding involves a single pass filler of 2mm, with a cladding rate typically between 7.2g / min and 8.2g / min. In contrast, the present invention achieves a single pass filler of 5mm to 6mm, with a cladding rate of 22.7g / min to 35.5g / min, representing a 3.6-fold increase in efficiency.

[0093] Example 2

[0094] The difference between this embodiment and embodiment 1 is that, in step 3, when welding the first layer, the wire feed speed is set to 1300mm / min to 1600mm / min. For subsequent filling layers, the current decreases sequentially, by 15A to 20A per layer. After welding four layers, the current is set to 480A to 560A. The protective gas is a helium-argon mixture with a helium-argon ratio of 7:3 and a gas flow rate of 20L / min to 30L / min.

[0095] Using a helium-argon mixed protective gas can significantly improve the flow stability of the molten pool and the stability of the arc, which is beneficial for the excessive droplet flow during deep and narrow gap welding and results in a beautiful weld formation. The addition of helium makes the molten pool width slightly increase inside the narrow gap, enhancing the fusion effect of the narrow gap sidewall.

[0096] Based on Example 1, this embodiment overcomes the influence of deep and narrow gaps on arc energy by using a helium-argon mixed protective gas and stepped current welding. It is suitable for high-efficiency TIG welding of 60mm to 100mm thick titanium alloys with narrow gaps, and significantly improves welding efficiency while ensuring welding quality.

[0097] In this embodiment, an 87mm thick TC4ELI titanium alloy is used, with a bottom bevel width of 9mm, a top width of 14mm, and a blunt edge of 2mm.

[0098] The apparatus and method for high-efficiency TIG welding of thick titanium alloys with narrow gaps described in this application have the following advantages: 1. By setting a blind hole 32 at the bottom of the tungsten electrode 31, the length of the hollow part inside the tungsten electrode 31 is shortened, which greatly reduces the processing difficulty and production cost of the tungsten electrode 31, and can obtain an "M"-shaped arc, which greatly improves the welding deposition rate and welding efficiency, and achieves good fusion of the two sidewalls of the narrow gap. Setting an insulating ceramic rod in the blind hole 32 achieves insulation between the blind hole 32 and the welding wire 22; 2. By adjusting the welding parameters and the distance between the tungsten electrode 31 and the test plate 100, the "M"-shaped arc can be adjusted so that the two legs of the arc are located on the two sidewalls, which enhances the fusion effect of the two sidewalls of the narrow gap, and further improves the welding deposition rate and welding efficiency.

[0099] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. An apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps, characterized in that, include: An insulating plate (1) is provided with a wire feeding device (2) and a tungsten inert gas (TIG) welding torch (3). The wire feeding device (2) includes a wire feeding nozzle (21) that can move in three-dimensional space for feeding welding wire (22) during welding. A tungsten electrode (31) is installed at the lower part of the TIG welding torch (3). A blind hole (32) is provided at the lower part of the tungsten electrode (31). An insulating ceramic rod is provided in the blind hole (32). The tungsten electrode (31) includes a first tungsten electrode (311) and a second tungsten electrode (312). The first tungsten electrode (311) is provided with a first blind hole (3110). The diameter of the first blind hole (3110) is d1, 1.5mm≥d1≥1.0mm, and the wall thickness of the lower end of the first blind hole (3110) is h1, 0.8mm≥h1≥0.3mm. The second tungsten electrode (312) is provided with a second blind hole (3120). The diameter of the second blind hole (3120) is d2, 3mm≥d2≥1.5mm, and the wall thickness of the lower end of the second blind hole (3120) is h2, 0.6mm≥h2≥0.3mm. The three-axis slide (4) is equipped with an insulating plate (1) so that the tungsten inert welding torch (3) can move relative to the test plate (100); Welding power source (5) is connected to tungsten inert gas torch (3) and is used to supply power to tungsten inert gas torch (3); The controller (10) controls the working status of the wire feeding device (2), welding power supply (5) and triaxial slide (4) according to the set parameters, and performs welding on the test plate (100).

2. The apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps according to claim 1, characterized in that, The diameter of the tungsten electrode (31) is D, 8.0 mm ≥ D ≥ 5.0 mm, and the lower end of the tungsten electrode (31) is set as a conical surface with an angle B, 60° ≥ B ≥ 40°.

3. The apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps according to claim 1, characterized in that, The distance between the lower end of the tungsten electrode (31) and the test plate (100) is 5.0 mm to 9.0 mm.

4. The apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps according to claim 1, characterized in that, The tungsten inert gas (TIG) welding torch (3) is equipped with a circulating water pipe and a gas pipe. The circulating water pipe is connected to the circulating water tank (61) through a pipeline and is used to cool the TIG welding torch (3) during the welding process. The gas pipe is connected to the first protective gas tank (71) through a pipeline and is used to spray protective gas onto the welding area on the test plate (100) during the welding process.

5. The apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps according to claim 1, characterized in that, It also includes a protective device (8), which is located at the lower part of the test plate (100). The protective device (8) includes a gas protection tank (81) and a cooling tank (82). The gas protection tank (81) is connected to a second protective gas tank (72) through a pipeline and is used to provide gas protection to the lower part of the test plate (100) during the welding process. The cooling tank (82) is connected to a cooling water tank (62) through a pipeline and is used to cool the lower part of the test plate (100) during the welding process.

6. The apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps according to claim 1, characterized in that, The test plate (100) includes a first test plate (101) and a second test plate (102). A U-shaped bevel (103) is provided on the test plate (100). The bottom width of the U-shaped bevel (103) is N1, N1≥8mm, and the top width is N2, N2≤15mm.

7. The apparatus for high-efficiency TIG welding of thick titanium alloys with narrow gaps according to claim 6, characterized in that, The distance between the first test plate (101) and the second test plate (102) is L1, and the misalignment is L2, where 0.2mm≥L1 and 0.5mm≥L2. The misalignment refers to the height difference between the first test plate (101) and the second test plate (102).

8. A method for high-efficiency TIG welding of thick titanium alloys with narrow gaps, employing the TIG welding apparatus according to any one of claims 1 to 6, characterized in that, Including the following steps: Step 1: Mechanically clean the surface of the test plate (100) and the U-shaped groove (103) to be welded, then wipe it clean with acetone, place the test plate (100) on the protective device (8), teach the trajectory of the tungsten inert welding torch (3), set the welding parameters in the controller, and start the protective device (8). Step 2: Perform root pass welding on the test plate (100), replace the first tungsten electrode (311), adjust the distance between the first tungsten electrode (311) and the test plate (100), set the current range to 220A~300A, the welding speed to 110mm / min~150mm / min, the shielding gas flow rate to 15L / min~25L / min, and the wire feed speed to 250mm / min~500mm / min. After the root pass welding of the test plate (100) is completed, proceed to step 3. Step 3: Weld filler is applied to the test plate (100). Replace the second tungsten electrode (312), adjust the distance between the second tungsten electrode (312) and the test plate (100). When performing the first layer of welding filler, the current is set to 420A~500A, the welding speed is set to 110mm / min~130mm / min, the shielding gas flow rate is set to 20L / min~30L / min, and the wire feed speed is set to 1500mm / min~1800mm / min. When performing the remaining layers of welding filler, the current is set to 500A~650A, the welding speed is set to 80mm / min~110mm / min, the shielding gas flow rate is set to 20L / min~30L / min, the wire feed speed is set to 1800mm / min~2500mm / min, the pulse frequency is set to 50Hz~80Hz, and the duty cycle is set to 80%. Weld filler is applied alternately to the upper and lower sides of the test plate (100). When the filler reaches 2~3mm from the upper surface of the test plate (100), stop and proceed to step 4. Step 4: Perform welding cover operation on the test plate (100), using the second tungsten electrode (312), with the pulse frequency set to 2Hz~10Hz, the duty cycle set to 60%~80%, the current set to 360A~450A, the welding speed set to 110~150mm / min, the wire feed speed set to 1300~2000mm / min, and the shielding gas flow rate set to 25L / min~35L / min.

9. The method for high-efficiency TIG welding of thick titanium alloys with narrow gaps according to claim 8, characterized in that, In step 3, during the first layer of welding filler, the wire feed speed is set to 1300mm / min~1600mm / min. For subsequent filler layers, the current decreases sequentially, by 15A~20A per layer. After welding filler four layers, the current is set to 480A~560A. The shielding gas is a helium-argon mixture with a helium-argon ratio of 7:3 and a gas flow rate of 20L / min~30L / min.

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