Gas nozzle device with variable gas flow protection and method for repairing turbine blade through wire precision laser welding by using gas nozzle device

Abstract

The invention discloses a variable-airflow-protection gas nozzle device and a method for repairing a turbine blade through wire precise laser welding by using the variable-airflow-protection gas nozzle device, and belongs to the technical field of laser welding repairing of aero-engines and gas turbine blades. The problems that in an existing turbine blade laser welding repairing process, protection cannot be achieved at the same time, operation is easy, the welding process is monitored, oxidation of molten metal, pollution of metal steam and molten drop splashing are restrained, and irregular multi-profile laser welding quality protection cannot be achieved are solved. The device is composed of two arc-shaped columnar shells, a protective airflow net and a sealing cover, a first cavity, a second cavity and a third cavity are formed, and a plurality of gas outlets are formed in the protective airflow net; the method comprises the following steps: 1, clamping and setting; 2, symmetrically fixing the two sides of the blade clamp; and thirdly, wire precise laser welding repair is conducted under a protective gas hood. The invention relates to a gas nozzle device for variable gas flow protection and a method for repairing a turbine blade by using the gas nozzle device for wire precision laser welding.

Description

Technical Field

[0001] The invention belongs to the technical field of laser welding and repairing of aircraft engine and gas turbine blades. Background Art

[0002] At present, most of the turbine blades in the aviation field are directionally solidified nickel-based high-temperature alloys, which have excellent creep resistance and compressive yield strength properties, and still have good mechanical properties and corrosion and fatigue resistance in high temperature environments. The high temperature environment during turbine operation will cause corrosion, oxidation, thermal fatigue and mechanical fatigue of turbine blades and nozzles. Due to the high replacement cost of turbine blades, effective repair can reduce the full life cycle cost of the engine. Therefore, various turbine blade repair procedures have been developed. Laser welding of the crown of turbine blades can increase the strength of the cladding layer, reduce costs, and achieve a more reliable connection.

[0003] In order to prevent the molten metal pool from coming into contact with active elements and being oxidized during the turbine blade welding process, and the turbine blade structure is complex and multi-surfaced, a special welding shielding gas nozzle is required to add welding shielding gas. During the laser welding of blades, the molten metal droplets are protected by inert gas (welding protection medium), which can effectively reduce weld defects, such as: oxidation of molten metal, contamination of metal vapor, and splashing of molten droplets. Improper delivery of inert shielding gas or insufficient stability of shielding gas flow can easily cause oxidation of the weld, which will significantly reduce welding quality and performance. Therefore, during the laser welding of blades, the design of flexible protection devices for complex and multi-surfaces is a technical difficulty in achieving efficient and high-quality welding.

[0004] The current welding protection devices can be divided into three types of protection: closed protection, side-blowing and coaxial blowing. The closed protection provides a closed environment for the welding of the workpiece during the welding process, inhibiting its oxidation, but the structure of the blade is complex, laser welding is difficult to operate in a closed environment, and it is difficult to monitor the welding process, so it cannot be widely used. The side-blowing protection method has a simple structure, is easy to install, and is relatively flexible, but due to the fixed output direction of the shielding gas, the consistency of the weld formation quality is not high during variable direction processing, and it is even more difficult to apply to the multi-shaped surfaces of turbine blades. Since the coaxial blowing protection requires the use of wire feeding to fill the metal during the blade welding process, it is difficult to provide good welding protection for the molten metal.

[0005] In summary, the closed protection method has a good welding protection effect, but at present, due to the multi-surface structure of the blade and the limited space for wire feeding and filling metal, it is not possible to achieve efficient welding repair of the blade. Summary of the invention

[0006] The present invention aims to solve the problems that the protection in the existing turbine blade laser welding repair process cannot simultaneously achieve simple operation, monitor the welding process, inhibit the oxidation of molten metal, metal vapor contamination and molten droplet splashing, as well as the quality of irregular multi-surface laser welding protection, and further provide a gas nozzle device with variable airflow protection and a method for using the same to perform wire precision laser welding to repair turbine blades.

[0007] A gas nozzle device for variable airflow protection, which consists of two arc-shaped columnar shells, a protective airflow net and a sealing cover;

[0008] The inner wall of the arc-shaped cylindrical shell is provided with three grooves in sequence along the circumferential direction, the upper end surfaces and inner side surfaces of the three grooves are open structures, a sealing cover is provided on the upper end surface of the arc-shaped cylindrical shell, a protective airflow net is provided on the inner wall surface of the arc-shaped cylindrical shell, and the inner wall of the arc-shaped cylindrical shell, the sealing cover and the protective airflow net form a first chamber, a second chamber and a third chamber; the protective airflow net is provided with a plurality of gas outlets in an array at positions corresponding to the first chamber, the second chamber and the third chamber;

[0009] The first chamber, the second chamber and the third chamber are provided with gas inlets at the bottom, and a plurality of gas flow channel partition plates are longitudinally and parallelly arranged inside;

[0010] The two arc-shaped columnar shells have the same structure and are symmetrically arranged.

[0011] The beneficial effects of the present invention are:

[0012] The present invention uses different chambers to form laminar flows with different flow rates. Based on the fact that the shielding gas input flow rates of the first chamber and the third chamber are the same, the shielding gas input flow rate ratio of the first chamber to the second chamber is (0.9-1.2):1, and the fan angle corresponding to the second chamber is larger than that of the first chamber and the third chamber, which leads to the volume of the second chamber being larger than that of the first chamber and the third chamber. Therefore, high-speed shielding gas output is formed on both sides, and stable and slow shielding gas output is formed inside. The airflows on both sides are protective layers. The internal airflow protects the molten metal during the laser welding process to prevent oxidation, forming a quasi-closed protection mode, and providing a protection method for the laser wire feeding welding repair of blade crown multi-profiles. The specific advantages are as follows:

[0013] 1. The device of the present invention can achieve full coverage of the protective gas during the laser welding process of repairing the multi-surface parts of the blade. The chamber structure forms a gas hood with low internal pressure and high pressure on both sides through gases with different output flow rates. At the same time, it cooperates with the fairing to accurately control the protection area of ​​the protective gas, effectively inhibiting the oxidation of the molten metal during laser welding.

[0014] 2. The device of the present invention does not interfere with the welding process. Compared with the side axis, the protection range is larger. There is enough space between the protective gas nozzles on both sides to facilitate the swing during laser welding, and the welding wire can be effectively delivered. For the blades precisely repaired by laser fuse welding, quasi-closed protection is achieved. This method can reduce the oxidation of the molten metal in the cladding layer, reduce the spatter during welding, reduce the porosity of the weld, etc., and does not affect the operating space of the wire feeding device and the laser head.

[0015] 3. The device of the present invention has good protection effect. The various parts of the laser welding shielding gas nozzle are tightly connected, with good sealing and no air leakage. The shielding gas flows into the cavity through the air inlet and flows out from the shielding gas outlet, achieving the effect of overall protection and obtaining a surfacing layer with good forming quality.

[0016] 4. The device of the present invention is easy to install and disassemble, has high adaptability, is convenient to operate, can monitor the welding process, can be installed on both sides of the repaired blade, and is also suitable for protection during welding of other multi-shaped surfaces, with high adaptability.

[0017] Instruction Manual

[0018] Figure 1 It is a schematic diagram of the overall structure of the gas nozzle device for variable airflow protection of the present invention;

[0019] Figure 2 A front view of a gas nozzle device for variable airflow protection according to the present invention;

[0020] Figure 3 An internal view of a chamber of a gas nozzle device for variable gas flow protection according to the present invention;

[0021] Figure 4 A diagram showing the positional relationship between the protective gas flow net and the chamber of the gas nozzle device for variable gas flow protection of the present invention;

[0022] Figure 5 A schematic diagram of the angles between chambers of a gas nozzle device for variable gas flow protection in Example 1;

[0023] Figure 6 A schematic diagram of the structure of a positioning device of a gas nozzle device for variable airflow protection of the present invention;

[0024] Figure 7 To compare the surface and cross-sectional morphology of the DZ125 alloy blade cladding layer welded by laser wire feeding under side-axis protection;

[0025] Figure 8 The surface and cross-sectional morphology of the DZ125 alloy blade cladding layer welded by laser wire feeding under variable airflow type closed protection in Example 1;

[0026] Among them, 1-arc-shaped cylindrical shell; 2-fairing; 3-protective airflow net; 4-positioning device; 5-turbine blades to be repaired; 6-wire feeding conductive nozzle and welding wire; 7-hose; 8-sealing cover; 9-gas inlet; 10-first chamber; 11-second chamber; 12-third chamber; 13-gas flow channel partition plate. DETAILED DESCRIPTION

[0027] Specific implementation method 1, combined with Figures 1 to 4 6 specifically describes: This embodiment is a gas nozzle device for variable airflow protection, which is composed of two arc-shaped columnar shells 1, a protective airflow net 3 and a sealing cover 8;

[0028] The inner wall of the arc-shaped cylindrical shell 1 is provided with three grooves in sequence along the circumferential direction, and the upper end surfaces and inner side surfaces of the three grooves are open structures. A sealing cover 8 is provided on the upper end surface of the arc-shaped cylindrical shell 1, and a protective airflow net 3 is provided on the inner wall surface of the arc-shaped cylindrical shell 1. The inner wall of the arc-shaped cylindrical shell 1, the sealing cover 8 and the protective airflow net 3 form a first chamber 10, a second chamber 11 and a third chamber 12; the protective airflow net 3 is provided with a plurality of gas outlets in an array at positions corresponding to the first chamber 10, the second chamber 11 and the third chamber 12;

[0029] The first chamber 10, the second chamber 11 and the third chamber 12 are provided with a gas inlet 9 at the bottom, and a plurality of gas flow channel partition plates 13 are longitudinally and parallelly arranged inside;

[0030] The two arc-shaped columnar shells 1 have the same structure, and the two arc-shaped columnar shells 1 are symmetrically arranged.

[0031] The beneficial effects of this embodiment are:

[0032] This embodiment uses different chambers to form laminar flows with different flow rates. Based on the same shielding gas input flow rate of the first chamber and the third chamber, the shielding gas input flow rate ratio of the first chamber to the second chamber is (0.9-1.2):1, and the fan angle corresponding to the second chamber is larger than that of the first chamber and the third chamber, which leads to the volume of the second chamber being larger than that of the first chamber and the third chamber. Therefore, high-speed shielding gas output is formed on both sides, and stable and slow shielding gas output is formed inside. The airflow on both sides is a protective layer. The internal airflow protects the molten metal during laser welding to prevent oxidation, forming a quasi-closed protection mode, providing a protection method for laser wire feeding welding repair of blade crown multi-profiles. The specific advantages are as follows:

[0033] 1. The device of this embodiment can achieve full coverage of the protective gas during the laser welding process of repairing the multi-surface parts of the blade. The chamber structure forms a gas hood with low internal pressure and high pressure on both sides through gases with different output flow rates. At the same time, it cooperates with the fairing to accurately control the protection area of ​​the protective gas, effectively inhibiting the oxidation of the molten metal during laser welding.

[0034] 2. This implementation type device does not interfere with the welding process. Compared with the side axis protection range, it has a larger range. There is enough space between the two-sided protective gas nozzles to facilitate the swing during laser welding, and the welding wire can be effectively delivered. For the blades that are precisely repaired by laser fuse welding, quasi-closed protection is achieved. This method can reduce the oxidation of the molten metal in the cladding layer, reduce spatter during welding, reduce the porosity of the weld, etc., and does not affect the wire feeding device and the laser head operating space.

[0035] 3. The device of this embodiment has good protection effect. The various parts of the laser welding shielding gas nozzle are tightly connected, with good sealing and no air leakage. The shielding gas flows into the cavity through the air inlet and flows out from the shielding gas outlet, achieving the effect of overall protection and obtaining a surfacing layer with good forming quality.

[0036] 4. The device of this embodiment is easy to install and disassemble, has high adaptability, is convenient to operate, can monitor the welding process, can be installed on both sides of the repaired blade, and is also suitable for protection during welding of other multi-shaped surfaces, with high adaptability.

[0037] Specific embodiment 2: This embodiment is different from the specific embodiment 1 in that the sector angle of the arc columnar housing 1 is 140° to 155°. The rest is the same as the specific embodiment 1.

[0038] Specific embodiment 3: This embodiment is different from specific embodiment 1 or 2 in that the first chamber 10 and the third chamber 12 have the same structure. The rest is the same as specific embodiment 1 or 2.

[0039] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the first chamber 10 and the third chamber 12 have the same structure. The rest is the same as specific embodiments 1 to 3.

[0040] Specific embodiment 5: This embodiment is different from specific embodiments 1 to 4 in that the second chamber 11 is disposed in the middle of the arc-shaped cylindrical housing 1, and the first chamber 10 and the third chamber 12 are symmetrically disposed on both sides of the second chamber 11. Other aspects are the same as specific embodiments 1 to 4.

[0041] Specific implementation example 6: This implementation example is different from specific implementation examples 1 to 5 in that the diameters of the multiple gas outlets are all 2 mm to 4 mm. The rest is the same as specific implementation examples 1 to 5.

[0042] Specific embodiment 7: This embodiment is different from specific embodiments 1 to 6 in that: the two arc-shaped columnar housings 1 are arranged on the positioning device 4; the gas inlet 9 is connected to the hose 7. The rest is the same as specific embodiments 1 to 6.

[0043] Specific embodiment 8: This embodiment is different from specific embodiments 1 to 7 in that a fairing 2 is provided on the sealing cover 8. The rest is the same as specific embodiments 1 to 7.

[0044] Specific embodiment 9: This embodiment is a method for repairing turbine blades by wire precision laser welding using a gas nozzle device with variable airflow protection, which is carried out in the following steps:

[0045] 1. Clamp the turbine blade to be repaired and set the path and defocus of laser welding;

[0046] Second, two arc-shaped columnar shells 1 of the gas nozzle device with variable airflow protection are fixed symmetrically on both sides of the blade clamp through the positioning device 4, and an operating space for the wire feeding conductive nozzle and the welding wire is left between the two arc-shaped columnar shells 1;

[0047] 3. The shielding gas input flow rates of the first chamber 10 and the third chamber 12 are set to be the same, and are both 10L / min to 25L / min. The shielding gas input flow rate ratio of the first chamber (10) to the second chamber (11) is (0.9 to 1.2):1. The shielding gas is guided through the chamber and the gas flow channel and then sent out to form a shielding gas hood. The shielding gas hood covers the laser welding area of ​​the blade. Wire precision laser welding repair is performed under the shielding gas hood, thereby completing the method of wire precision laser welding repair of turbine blades.

[0048] After the blade workpiece is clamped, the robot sets the path and defocus amount. The two arc-shaped cylindrical shells 1 are symmetrically fixed on both sides of the blade to be repaired by the positioning device 4, completely covering the blade welding area. At the same time, the two arc-shaped cylindrical shells 1 leave enough operating space for the wire feeding conductive nozzle and the welding wire 6. The shielding gas nozzle device is coaxial with the laser head, which is convenient for the laser to reach the workpiece surface to be welded directly during the repair process. The gas nozzle joint introduces the shielding gas through the hose 7. The shielding gas passes through the gas flow channel and finally sprays out through the shielding gas flow net 3, forming a shielding gas chamber with a small blowout airflow in the second chamber 11 and a large blowout airflow in the first chamber 10 and the third chamber 12, realizing the quasi-closed protection of variable airflow. At the same time, the existence of the fairing 2 above the shielding gas nozzle reduces the waste of gas and forms a complete shielding gas chamber.

[0049] Specific embodiment 10: This embodiment differs from specific embodiment 9 in that the gas nozzle device for variable gas flow protection described in step 2 is coaxial with the laser head. The rest is the same as specific embodiment 9.

[0050] The following examples are used to verify the beneficial effects of the present invention:

[0051] Embodiment 1:

[0052] A gas nozzle device for variable airflow protection, which consists of two arc-shaped columnar shells 1, a protective airflow net 3 and a sealing cover 8;

[0053] The inner wall of the arc-shaped cylindrical shell 1 is provided with three grooves in sequence along the circumferential direction, and the upper end surfaces and inner side surfaces of the three grooves are open structures. A sealing cover 8 is provided on the upper end surface of the arc-shaped cylindrical shell 1, and a protective airflow net 3 is provided on the inner wall surface of the arc-shaped cylindrical shell 1. The inner wall of the arc-shaped cylindrical shell 1, the sealing cover 8 and the protective airflow net 3 form a first chamber 10, a second chamber 11 and a third chamber 12; the protective airflow net 3 is provided with a plurality of gas outlets in an array at positions corresponding to the first chamber 10, the second chamber 11 and the third chamber 12;

[0054] The first chamber 10, the second chamber 11 and the third chamber 12 are provided with a gas inlet 9 at the bottom, and three gas flow channel partition plates 13 are longitudinally and parallelly provided inside the first chamber 10, the second chamber 11 and the third chamber 12;

[0055] The two arc-shaped columnar shells 1 have the same structure, and the two arc-shaped columnar shells 1 are symmetrically arranged;

[0056] The arc-shaped columnar housing 1 has a sector angle of 150°, a radius of 150 mm, and a height of 200 mm;

[0057] The first chamber 10 and the third chamber 12 have the same structure;

[0058] The sector angles of the first chamber 10 and the third chamber 12 are both 30°; the sector angle of the second chamber 11 is 50°; and the interval sector angles between the first chamber 10, the third chamber 12 and the second chamber 11 are all 5°; the interval sector angle between one side of the first chamber 10 and one side of the adjacent arc-shaped cylindrical housing 1 is 15°;

[0059] The second chamber 11 is disposed in the middle of the arc-shaped cylindrical housing 1 , and the first chamber 10 and the third chamber 12 are symmetrically disposed on both sides of the second chamber 11 .

[0060] The diameters of the multiple gas outlets are all 3 mm, and the protective air flow net 3 corresponding to the positions of the first chamber 10 and the third chamber 12 are arrayed with 24 rows × 10 columns of gas outlets, and the protective air flow net 3 corresponding to the position of the second chamber 11 is arrayed with 24 rows × 16 columns of gas outlets.

[0061] The two arc-shaped cylindrical shells 1 are arranged on the positioning device 4. The positioning device 4 has two threaded holes with a diameter of 4 mm, which are connected to the arc-shaped cylindrical shell 1 by bolts; the gas inlet 9 is connected to the hose 7, and the diameter of the hose 7 is 8 mm.

[0062] The sealing cover 8 is provided with a fairing 2; the fairing 2 and the protective airflow net 3 are fixed to the arc-shaped columnar housing 1 by bolts through threaded holes with a diameter of 2 mm.

[0063] The method for repairing turbine blades by wire precision laser welding using the above-mentioned variable airflow protection gas nozzle device is carried out in the following steps:

[0064] 1. Clamp the turbine blade to be repaired and set the path and defocus of laser welding;

[0065] Second, two arc-shaped columnar shells 1 of the gas nozzle device with variable airflow protection are fixed symmetrically on both sides of the blade clamp through the positioning device 4, and an operating space for the wire feeding conductive nozzle and the welding wire is left between the two arc-shaped columnar shells 1;

[0066] 3. The shielding gas input flow rates of the first chamber 10 and the third chamber 12 are set to be the same, both at 15 L / min, and the shielding gas input flow rate of the second chamber 11 is 15 L / min. The shielding gas is guided through the chamber and the gas flow channel and then sent out to form a shielding gas hood. The shielding gas hood covers the laser welding area of ​​the blade. Under the conditions of the shielding gas hood, a laser power of 650 W, a welding speed of 0.06 m / min and a wire feeding speed of 0.72 m / min, wire precision laser welding repair is performed using welding wire, thereby completing the method of wire precision laser welding repair of turbine blades.

[0067] The gas nozzle device for variable airflow protection described in step 2 is coaxial with the laser head.

[0068] The material of the turbine blade to be repaired in step 1 is DZ125; the material of the welding wire in step 2 is CoCrW, and the CoCrW is composed of 29.64% Cr, 1.15% C, 4.12% W and the balance Co in mass percentage.

[0069] Comparative experiment: The difference between this comparative experiment and the first embodiment is that under the same laser welding process parameters, the laser welding with side-shaft protection is adopted, and the flow rate of the protective gas is 15 L / min. The rest is the same as the first embodiment.

[0070] Figure 7 To compare the surface and cross-sectional morphology of the DZ125 alloy blade cladding layer welded by laser wire feeding under side-axis protection; Figure 8 This is the surface and cross-sectional morphology of the DZ125 alloy blade cladding layer welded by laser wire feeding under variable airflow type closed protection in Example 1. Figure 7 and Figure 8In order to study the morphology of the surfacing layer of high-temperature alloy turbine blades under the same laser welding process parameters, the laser welding with paraxial protection and the laser welding with variable gas flow protection gas nozzle device were used. It can be seen that under paraxial protection, the laser fuse was welded and repaired on the multi-profile surface of the blade, the protective gas flow rate was 15L / min, the surface of the surfacing layer had no bright white metallic luster, and the oxidation was extremely serious. The parent material was blue due to heat accumulation, the surfacing layer was discontinuous, and the molten metal splashed seriously during the welding process; observing the cross-sectional morphology of the surfacing layer, it can be seen that there are many inclusions in the cross section, the organization is unevenly distributed, and there are defects such as pores. Under the same process parameters, a quasi-closed protection method with variable airflow is adopted. The shielding gas input flow rates of the first chamber, the second chamber and the third chamber are all 15L / min, and the fan angle corresponding to the second chamber is larger than that of the first chamber and the third chamber, which leads to the volume of the second chamber being larger than that of the first chamber and the third chamber. Therefore, a gas shield with high-speed shielding gas output on both sides and stable and slow shielding gas output inside is formed. The surface of the surfacing layer presents a bright white metallic luster, the forming is continuous, the oxidation of the parent material is effectively suppressed, there is no spatter during welding, and the protection effect is excellent compared with the side-axis protection. At the same time, the cross-section of the surfacing layer is uniform, without defects such as pores and inclusions, which greatly improves the stability of the molten droplet transition during the welding process of the turbine blades, improves the welding quality of multi-surface components, and greatly improves the welding efficiency, and its welding efficiency can be increased by more than 2 times.

Claims

1. A gas nozzle device for variable airflow protection, characterized in that It consists of two arc-shaped columnar shells (1), a protective airflow net (3) and a sealing cover (8); The inner wall of the arc-shaped columnar shell (1) is provided with three grooves in sequence along the circumferential direction, the upper end surfaces and inner side surfaces of the three grooves are open structures, a sealing cover (8) is provided on the upper end surface of the arc-shaped columnar shell (1), a protective airflow net (3) is provided on the inner wall surface of the arc-shaped columnar shell (1), and the inner wall of the arc-shaped columnar shell (1), the sealing cover (8) and the protective airflow net (3) form a first chamber (10), a second chamber (11) and a third chamber (12); the protective airflow net (3) is provided with a plurality of gas outlets in an array at positions corresponding to the first chamber (10), the second chamber (11) and the third chamber (12); The first chamber (10), the second chamber (11) and the third chamber (12) are provided with a gas inlet (9) at the bottom, and a plurality of gas flow channel partition plates (13) are longitudinally and parallelly arranged inside; The two arc-shaped columnar shells (1) have the same structure, and the two arc-shaped columnar shells (1) are symmetrically arranged.

2. A gas nozzle device for variable airflow protection according to claim 1, characterized in that The sector angle of the arc-shaped columnar housing (1) is 140° to 155°.

3. A gas nozzle device for variable airflow protection according to claim 1, characterized in that The first chamber (10) and the third chamber (12) have the same structure.

4. A gas nozzle device for variable airflow protection according to claim 3, characterized in that The sector angles of the first chamber (10) and the third chamber (12) are both 25° to 35°; the sector angle of the second chamber (11) is 40° to 60°.

5. A gas nozzle device for variable airflow protection according to claim 4, characterized in that The second chamber (11) is arranged in the middle of the arc-shaped columnar housing (1), and the first chamber (10) and the third chamber (12) are symmetrically arranged on both sides of the second chamber (11).

6. A gas nozzle device for variable airflow protection according to claim 1, characterized in that The diameters of the multiple gas outlets are all 2 mm to 4 mm.

7. A gas nozzle device for variable airflow protection according to claim 1, characterized in that The two arc-shaped columnar shells (1) are arranged on the positioning device (4); the gas inlet (9) is connected to the hose (7).

8. The gas nozzle device for variable airflow protection according to claim 1, characterized in that A fairing (2) is arranged on the sealing cover (8).

9. A method for repairing turbine blades by wire precision laser welding using a gas nozzle device with variable airflow protection as claimed in claim 1, characterized in that It is carried out in the following steps:

1. Clamp the turbine blade to be repaired and set the path and defocus of laser welding; Second, two arc-shaped columnar shells (1) of the gas nozzle device for variable gas flow protection are symmetrically fixed on both sides of the blade clamp through the positioning device (4), and an operating space for the wire feeding conductive nozzle and the welding wire is reserved between the two arc-shaped columnar shells (1); 3. The shielding gas input flow rates of the first chamber (10) and the third chamber (12) are set to be the same, and are both 10L / min to 25L / min. The shielding gas input flow rate ratio of the first chamber (10) to the second chamber (11) is (0.9 to 1.2):

1. The shielding gas is guided through the chamber and the gas flow channel and then sent out to form a shielding gas hood. The shielding gas hood covers the laser welding area of ​​the blade. Wire precision laser welding repair is performed under the shielding gas hood, thereby completing the method of wire precision laser welding repair of turbine blades.

10. The method for repairing turbine blades by wire precision laser welding using a gas nozzle device with variable airflow protection according to claim 9, characterized in that The gas nozzle device for variable airflow protection described in step 2 is coaxial with the laser head.

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