System and method for repairing hollow fan blades

Abstract

Systems and methods for repairing a hollow fan blade. The hollow fan blade has a concave portion and a convex portion secured together by a joint. An interior cavity of the hollow fan blade is evacuated. The method includes removing material from a damaged portion of the hollow fan blade and welding the damaged portion such that a temperature of the joint does not exceed a distortion temperature.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 366,707, filed June 21, 2022, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure generally relates to the repair of aircraft fan blades. More specifically, this disclosure relates to the repair of hollow fan blades of aircraft. Summary of the Invention

[0004] The following is a simplified summary of the invention to provide a basic understanding of certain aspects of the invention. This summary is not a broad overview of the invention. It is not intended to identify key elements of the invention or to define its scope. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed descriptions presented elsewhere herein.

[0005] The innovative aspect of the subject matter described in this disclosure can be realized as a method for repairing hollow fan blades. The hollow fan blade includes a first part and a second part fixed together by a coupling. The internal cavity of the hollow fan blade is filled with a vacuum. The method includes removing material from the damaged portion of the hollow fan blade and welding the damaged portion such that the temperature of the coupling does not exceed the deformation temperature.

[0006] An aspect of the method includes arranging a thermocouple on at least one of the first and second portions.

[0007] Aspects of the method include using thermocouples to monitor the temperature of a portion of the hollow fan blades during welding.

[0008] Aspects of the method include arranging multiple thermocouples on each of the first and second parts.

[0009] An aspect of the method includes arranging each of a plurality of thermocouples using at least one selected from the group consisting of spot welding and adhesives.

[0010] One aspect of this method is that the hollow fan blades are fixed inside the cleaning box before welding.

[0011] An aspect of the method includes placing a gas pad on at least one of the first and second portions to disperse an inert gas during welding.

[0012] One aspect of this method is the use of a cooling system to cool the blades during welding.

[0013] In one aspect of the method, the cooling system includes at least one of a copper block and a water-cooled block.

[0014] In this method, welding includes tungsten inert gas (TIG) welding.

[0015] In one aspect of the method, the internal cavity further includes a honeycomb structure.

[0016] One aspect of this method is the application of finishing processes after welding.

[0017] In this method, the joint includes a brazed joint.

[0018] Another inventive aspect of the subject matter described in this disclosure can be implemented as a system for repairing hollow fan blades. The hollow fan blade includes a first part and a second part fixed together by a coupling. The internal cavity of the hollow fan blade is evacuated. The system includes a cleaning chamber with mounting parts for securing the hollow fan blade. The system includes thermocouples configured to monitor the temperature of the hollow fan blade during the welding process.

[0019] In this aspect of the system, the system further includes a cooling device for cooling the first and second parts of the blade during welding.

[0020] In one aspect of the system, the system further includes at least one gas pad disposed on at least one of the first and second portions for distributing inert gas during welding.

[0021] In this aspect of the system, the hollow fan blades further include a honeycomb structure within the internal cavity.

[0022] Another innovative aspect of the subject matter described in this disclosure can be implemented as a method for repairing hollow fan blades. The hollow fan blade includes concave and convex portions fixed together by a joint. The internal cavity of the hollow fan blade is filled with a vacuum. The method includes removing material from the damaged portion of the hollow fan blade. The method also includes repairing the damaged portion using welding, such that the temperature of the joint does not exceed the deformation temperature.

[0023] A further aspect of the method includes using a temperature sensor to monitor the temperature of the joint during welding.

[0024] An aspect of the method includes arranging at least one gas pad near the joint on at least one of the concave and convex portions for dispersing inert gas during welding.

[0025] Details of one or more embodiments of the subject matter described in this disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. Note that the relative dimensions in the following drawings may not be drawn to scale. Attached Figure Description

[0026] The illustrated aspects of this disclosure are described in detail below with reference to the accompanying drawings, in which:

[0027] Figure 1 It is a 3D view of a damaged hollow fan blade.

[0028] Figure 2 yes Figure 1 A cross-sectional view of a hollow fan blade.

[0029] Figure 3A yes Figure 2 The figure shows a cross-sectional view of the blade in its reduced region.

[0030] Figure 3B yes Figure 3A The cross-sectional view of the blade after a portion of the blade's reduced area has been removed.

[0031] Figure 3C yes Figure 3A The blade is shown in a cross-sectional view after the blade has undergone the welding process.

[0032] Figure 4A yes Figure 1 Another three-dimensional view of the leaf.

[0033] Figure 4B It is a three-dimensional view of a section of damaged blades that are equipped with thermocouples for monitoring temperature.

[0034] Figure 5 This illustrates the method used to maintain during the maintenance process. Figure 1 Side view of the cleaning box for damaged blades.

[0035] Figure 6 It shows a gas pad and cooling system. Figure 1 A side view of the damaged blade.

[0036] Figure 7 This is a flowchart illustrating an exemplary method for repairing hollow fan blades. Detailed Implementation

[0037] Fan blades guide air through and around an aircraft's engine. Fan blades are typically attached to a fan disk, which can be rotated by a shaft driven by the aircraft's gas turbine engine. The fan blades are the outermost rotating components of the aircraft engine. Because fan blades are exposed to the outside air, they can encounter foreign objects (e.g., birds, gravel, volcanic ash, and sand), resulting in damage such as, but not limited to, grooves, cuts, scratches, cracks, and splits. This damage can adversely affect the operating characteristics of the fan blades. One section of the fan blade that is particularly vulnerable to damage is the leading edge. The leading edge often wears and shortens with use, thus reducing the fan blade chord length (i.e., the tip-to-tip length measured in cross-section of the fan blade). This can undesirably affect the efficiency of the fan blade and, in some cases, may render the fan blade unusable.

[0038] In several respects, welding can be used to repair the damaged leading edge of a hollow fan blade. A hollow fan blade can typically be made of two shells brazed together. The interior of the hollow fan blade can be filled with a vacuum, which contributes to the structural integrity of the fan blade. To date, hollow fan blades have been considered unrepairable because conventional repair processes (such as welding) degrade the brazed joint and remove the vacuum, rendering the blade unsuitable for repair or use. In one aspect, a portion of the leading edge is removed and reconstructed using welding. Care is taken to ensure that the innermost surface of the removed portion of the leading edge is at least a minimum safe distance from the brazed joint. Performing welding repair at this minimum safe distance (or greater) ensures that the brazed joint does not reach the temperature that would damage it. Therefore, the damaged leading edge can be repaired without affecting the brazed joint and removing the vacuum. In an embodiment, the temperature at or near the leading edge can be monitored during welding to confirm that the brazed joint has not been heated to its damaging temperature.

[0039] One aspect that classifies aircraft engines is the bypass ratio. The bypass ratio of an aircraft engine is the ratio between the mass flow rate of the bypass flow and the mass flow rate entering the core. For the same thrust, increasing the bypass ratio can lead to reduced fuel consumption. The bypass ratio can be increased by increasing the size of the fan blades. However, increasing the size of the fan blades can adversely increase the engine's weight. To maintain this weight reduction, the fan blades can be made of relatively lightweight materials. Recently, one or more hollow cavities have been introduced into the fan blades to minimize concerns associated with the increased weight.

[0040] Damaged aircraft fan blades can be replaced. Alternatively, and depending on the type of damage, the fan blades can be repaired. When the fan blades are solid in structure, they can be repaired using one or more conventional techniques. For example, solid fan blades can be repaired using glass bead blasting or shot peening, or by applying welded repair patches. Hollow fan blades, which are less common than solid fan blades, may not be easy to repair using these conventional techniques. Such repair techniques may damage the vacuum within the hollow fan blades and render them unusable.

[0041] A hollow fan blade can be made of two housing halves and an intermediate support structure. The two housing halves may include concave and convex halves, and the intermediate support structure may be honeycomb-shaped. The two housing halves can be arranged around the support structure and can be fixed to each other via brazing joints. The support structure can also be brazed to the inner surfaces of the two housing halves. The hollow space between the two housing halves located next to the support structure can be filled with a vacuum, thereby creating a large pressure difference across the fan blade and the atmosphere. When the atmospheric pressure outside the two housings substantially exceeds the pressure inside the two housings, the atmospheric pressure pushes the housings with a compressive force proportional to the pressure difference between the inside and outside of the housings. In effect, the vacuum between the two housings can cause the housings to mimic the Magdeburg hemispheres. Therefore, the hollow fan blade is held together not only by the mechanical strength of the brazed joints securing the two housings but also by the pressure difference between the inside of the hollow fan blade and the atmosphere.

[0042] If the brazed joints securing the two housings are damaged, they may compromise the vacuum and destabilize the fan blades, rendering them unsuitable for repair or use. Common techniques used to repair solid fan blades and comparable gas turbine components (such as patch welding) can damage the brazed joints of hollow fan blades due to the excessive heat associated with these techniques. Therefore, such conventional techniques can eliminate the vacuum seal and permanently damage the blades. For at least this reason, hollow fan blades have historically been considered unrepairable. Embodiments of this disclosure may allow the repair of hollow fan blades without damaging the brazed joints.

[0043] Figure 1 and Figure 2 A hollow fan blade 50 is shown. The hollow fan blade 50 has a leading edge 60, a trailing edge 62 opposite to the leading edge 60, and a tip 64. The hollow fan blade 50 may include two housings, a convex or suction-side housing 66 and a concave or pressure-side housing 68 (see...). Figure 2 The housings 66 and 68 can be brazed together at the brazing joint line or at the brazed assembly 70. Figure 2The internal cavity 71 of the hollow fan blade 50 may include a honeycomb structure 72, which may be sandwiched between the convex housing 66 and the concave housing 68. The internal cavity 71 may be filled with a vacuum.

[0044] like Figure 1 As shown, a portion 74 of the leading edge 60 of the blade 50 is damaged. Damage to the leading edge 60 can be caused by a collision between the blade 50 and an external object (e.g., a bird, a stone, etc.). In several aspects of this disclosure, the damaged portion 74 of the leading edge 60 is repaired without damaging the brazed assembly 70. For example, welding can be used to repair the leading edge 60, and specifically, the damaged portion 74 of the leading edge 60, without affecting the brazed assembly 70. The welding process can be any suitable welding process now known or subsequently developed, such as tungsten inert gas (TIG) welding, gas metal arc welding, shielded metal arc welding, flux-cored arc welding, etc. In this embodiment, tungsten inert gas (TIG) welding can be employed.

[0045] In some aspects, the same or similar materials constituting the fan blade 50 can be used to repair the hollow fan blade 50. In embodiments, a bulk composition analysis of the hollow fan blade 50 can be performed to determine the composition of the blade 50. Hollow fan blades (including brazed joints therein) are typically formed of titanium or titanium alloys (e.g., Ti64 alloy). The hollow fan blade 50 can be formed of titanium or titanium alloys. The hollow fan blade 50 may additionally or alternatively include aluminum or stainless steel. Those skilled in the art will therefore understand that the techniques described herein can be applied to fan blades formed of any suitable metal.

[0046] The brazed joint 70 of the hollow fan blade 50 may not be heated above a certain temperature, as this would inappropriately alter the physical properties of the brazed joint 70 and damage the blade 50. For example, the applicant has found that the structural integrity of the brazed joint 70, including titanium, degrades beyond repair at or around 720°C (approximately 993.2 K). At or near this temperature, physical changes in the brazed joint 70 may damage the vacuum within the hollow fan blade 50. Therefore, care can be taken to ensure that the brazed joint 70 does not reach this temperature. The temperature at which the joint of a hollow fan blade (such as the brazed joint 70 of the hollow fan blade 50) deforms beyond repair and releases the vacuum therein may also be referred to here as the "deformation temperature". Those skilled in the art will understand that the deformation temperature of the joints of different hollow fan blades may vary based on the construction of these blades and joints.

[0047] Welding temperatures can easily exceed the deformation temperature of brazing or other joints used for a particular blade. For example, tungsten inert gas (TIG) welding temperatures can reach 3,000°C (3,723.2 K) or higher—far exceeding the deformation temperature of the brazed assembly 70 of the hollow fan blade 50. Therefore, conventional wisdom advises against using welding processes (such as patch welding or welding within material layers) to repair hollow fan blades, as excessively high welding temperatures could damage the brazed assembly 70 and release the vacuum, rendering the fan blade 50 unusable.

[0048] like Figure 3A As shown, in order to prepare the hollow fan blade 50 for welding repair processes, a minimum safety distance 102 from the brazed assembly 70 can be determined. As described herein, the minimum safety distance 102 can be a distance from the brazed assembly 70 from which welding repairs can be performed without causing the brazed assembly 70 to reach or exceed its deformation temperature. The minimum safety distance 102 can be defined in a reduction region 104 outside the minimum safety distance 102. Specifically, the reduction region 104 can extend inward from the leading edge 60 such that the innermost surface 106 of the reduction region 104 is at least spaced from the brazed assembly 70 by the minimum safety distance 102. The portion of the blade 50 within the reduction region 104 can be removed and repaired using welding processes.

[0049] In one aspect, the minimum safety distance 102 is between approximately 0.125 inches (approximately 3.175 mm) and approximately 0.375 inches (approximately 9.525 mm). For example, a user can safely remove approximately 0.25 inches (approximately 6.35 mm) of material from the brazed assembly 70. In several aspects, the reduction region 104 may include an area of ​​the fan blade 50 that is up to approximately 0.200 inches (approximately 5.08 mm) below the minimum chordal dimension of the Type Certificate Holder (TCH) for a given hollow fan blade 50 to be repaired, for example, between 0.1 inches (2.54 mm) and 0.3 inches (7.62 mm). Those skilled in the art will understand that the minimum safety distance can vary from blade to blade depending, for example, on the blade construction and the location of the brazed assembly.

[0050] Figure 3B A hollow blade 50' is shown. The hollow blade 50' is an example of a hollow blade 50 after the portion of the blade 50 within the reduction region 104 has been removed. Removal of the portion of the blade 50 within the reduction region 104 may leave a weld base 108. The weld base 108 may be a smooth surface that readily accepts weld material. Because the weld base 108 is spaced at least a minimum safety distance 102 from the brazed assembly 70, the brazed assembly 70 may not reach or exceed its deformation temperature during the welding process.

[0051] Figure 3C A hollow blade 50" is shown. The hollow blade 50" can be an example of a hollow blade 50' after the weld section 110 has been welded to the weld base 108 to repair the blade. The weld section 110 can be added to the hollow blade 50' without weakening the vacuum within the brazed assembly 70 or the blade 50.

[0052] In some respects, to ensure that the brazed joint 70 is not damaged during the brazing process, multiple thermocouples 118 or other suitable temperature sensors may be positioned close to the brazed joint 70 and the brazing substrate 108. Specifically, Figure 4A The section 116 of the damaged hollow fan blade 50, including the damaged leading edge 74, is shown. (See diagram.) Figure 4B As shown, multiple thermocouples (e.g., thermocouples 118A to 118I) may be positioned adjacent to the brazed joint 70 (e.g., at a location between the brazed joint 70 and the weld base 108) within section 116. Thermocouples 118A to 118I allow monitoring of the temperature at and around the brazed joint 70 to ensure that the brazed joint 70 does not approach, reach, or exceed its deformation temperature.

[0053] In the illustrated embodiment, thermocouples 118A to 118E are disposed on a convex or suction housing 66, and thermocouples 118F to 118I are disposed on a concave or pressure housing 68. The temperature of thermocouples 118A to 118I can be monitored during the welding repair process. If any thermocouple 118A to 118I indicates a temperature close to its deformation temperature, the welding process can be stopped or otherwise modified to prevent breakage of the brazed joint 70.

[0054] The distance between thermocouples 118A to 118I and the brazed joint 70 can affect the validity of temperature readings. For example, if the thermocouples are too far from the brazed joint 70, the temperature readings may be irrelevant to or not indicate the temperature at the brazed joint 70. In an embodiment, thermocouples 118A to 118I may be spaced about 1 inch apart from each other in the radial or y-axis direction and may be aligned anywhere from about 0.240 inches (6.096 mm) to 0.783 inches (19.888 m) in the x-axis direction from the leading edge 60. Table 1 below outlines the positions of thermocouples 118A to 118I in one example.

[0055]

[0056] Table 1: Locations of thermocouples 118A to 118I

[0057] Of course, the values ​​in Table 1 are merely exemplary and not intended to be limiting independently. Those skilled in the art will understand that thermocouples 118A to 118I can be arranged differently (e.g., the distance between two consecutive thermocouples 118A to 118I can be greater than or less than about one inch, and depending on the specific fan blade, can be further away from or closer to the leading edge). In some embodiments, thermocouples 118A to 118I can be secured (e.g., temporarily) to fan blade 50 using any suitable method (such as with adhesive or via spot welding).

[0058] In several respects, the hollow fan blades 50 can be located within the cleaning box 200 during maintenance processes. Figure 5 An example of a purging box 200 is shown. The purging box 200 may have a frame 202 and a mounting member 204. The mounting member 204 may be configured to securely hold at least a portion of the hollow fan blade 50, such as at its wedge-shaped tenon. The purging box 200 can be used to stabilize the blade 50 when it undergoes a welding process. In several respects, the purging box may be filled with a gas (e.g., an inert gas, such as argon). Those skilled in the art will understand that repair processes can be adversely affected by oxygen. During a repair process, the inert gas within the purging box can remove oxygen from the purging box 200 and reduce oxidation of the blade 50.

[0059] In some aspects, in addition to cleaning box 200, gas pad 300 can be used to facilitate welding repair processes (see...). Figure 6 Gas pad 300 may include gas pads 302 and 304. Gas pad 302 may be located on the convex housing 66, adjacent to the welding substrate 108, and gas pad 304 may be located on the concave housing 68, adjacent to the welding substrate 108. Gas pads 302 and 304 may disperse local inert gases from the welding material and eliminate or minimize any oxidation of the blade 50.

[0060] In one embodiment, one or more ice-cooling or chilling systems 306 may be arranged along or adjacent to the leading edge 60. These cooling systems 306 may include, for example, copper cooling blocks and / or water cooling blocks that can be used to reduce the temperature of the fan blades 50 during the welding process. The cooling systems 306 can help ensure that the brazed assembly 70 does not approach its deformation temperature during the welding repair process.

[0061] Figure 7This is a flowchart outlining an example method 400 for repairing a hollow fan blade 50. At step 402, a damaged portion of the leading edge 60 (e.g., damaged portion 74) can be identified. Damage may include cuts, scratches, dents, or other damage. At step 404, a minimum safe distance from the brazed assembly can be identified for the specific blade being repaired (e.g., minimum safe distance 102 from the brazed assembly 70). The minimum safe distance may be a distance from the brazed assembly at which welding repair can be performed without causing the brazed assembly to reach or exceed its deformation temperature. At step 406, a region of the leading edge of the blade within the reduction region (e.g., reduction region 104) can be removed to create a clean weld base (e.g., weld base 108). The reduction region 104 may be outside the brazed assembly, thus not entering the hollow interior of the fan blade 50. Specifically, the weld base may be at least spaced from the brazed assembly (e.g., brazed assembly 70) by a minimum safe distance. Minimum safety distances provide a buffer of material for the welding position and brazed joints used for repairs, ensuring that the brazed joints are unaffected by the heat generated during the welding process.

[0062] At step 408, multiple thermocouples, such as thermocouples 118A to 118I, can be arranged along the brazed joint associated with the damaged portion of the blade. The thermocouples can be temporarily fixed using, for example, spot welding or adhesive. The thermocouples allow monitoring of the fan blade temperature along the weld line adjacent to the joint during the welding repair process to ensure that the weld line temperature does not reach the deformation temperature.

[0063] At step 410, the hollow fan blades can be secured within a cleaning box (e.g., a mounting member 204 of the cleaning box 200) to minimize the possibility of oxidation of the fan blades during the welding repair process. At step 412, gas pads (e.g., gas pads 302, 304) can be positioned alone or together with a cooling feature (e.g., cooling feature 306) along the weld line of the blade portion being repaired.

[0064] At step 414, any suitable welding technique now known or subsequently developed (e.g., TIG welding, gas metal arc welding, shielded metal arc welding, flux-cored arc welding, etc.) can be used to weld material to the weld base (e.g., weld section 110 can be added to the weld base 108 via welding). In several aspects, the welding material can be added layer by layer, and each layer can be deposited after a period of time following the deposition of a previous layer. In one aspect, the welding process can include forming a weld fusion in layers (including six layers), wherein each layer can be applied within a window ranging from about four minutes to about six minutes. The application of each layer can be spaced about one minute apart from each layer. The application time of the layers can be provided in any number of layers, with any interval and time period between layers. The layers can be constructed onto the fan blade in any pattern, including but not limited to, starting in the middle of the blade and moving towards the blade tip. Note that care should be taken to ensure that the deformation temperature of the brazed assembly (e.g., brazed assembly 70) is not exceeded during the welding process so as not to damage the vacuum of the fan blade 50.

[0065] At step 416, the blade (e.g., newly welded material) can be finished to bring it to the desired specifications. Finishing the blade may involve, for example, machining down-weld fusion to ensure the shape and dimensions of the repaired blade are within the required tolerances, adding a surface coating, etc. In several aspects, machining tools (e.g., 5-axis machining tools) can be used to finish the blade and complete the repair process. At step 418, the repaired blade can be inspected to ensure it is operational. For example, the repaired blade can be visually inspected. In embodiments, X-ray scanning, depth profiling, fluorescence penetrant testing, eddy current testing, etc., can be used to evaluate the repaired blade. If evaluation is required, additional welding may be performed to ensure the repaired blade is flight-ready.

[0066] Those skilled in the art will understand that the steps of method 400 can be modified, added, and / or omitted as needed, and such considerations have been conceived and are within the scope of this disclosure. For example, those skilled in the art will understand that the step of arranging the thermocouple can be performed before removing material from the fan blades to create the reduced area, the thermocouple can be omitted entirely, or a different temperature sensor can be used.

[0067] As already described, various aspects of this disclosure can allow for the repair of hollow fan blades while mitigating or eliminating the risk that their brazed joints will be damaged or the vacuum within the blades will be compromised. In the repair process, the fan blades can be maintained by using material buffers and ensuring that deformation temperatures are not reached, the vacuum charge, and therefore the structural integrity. While the discussion herein focuses primarily on welding and repairing the leading edge of hollow fan blades, those skilled in the art will understand that the methods described herein can be adapted to welding any other suitable area of ​​a hollow fan blade.

[0068] Many different arrangements of the various components depicted, and those not shown, are possible without departing from the spirit and scope of this disclosure. Embodiments of this disclosure have been described with illustrative rather than limiting intent. Alternative aspects without departing from its scope will become apparent to those skilled in the art. Alternative means for achieving the above improvements can be developed by those skilled in the art without departing from the scope of this disclosure. It should be understood that certain features and sub-combinations are useful and can be used without reference to other features and sub-combinations, and are contemplated within the scope of the claims. Not all steps described herein and / or listed in the various figures need to be performed or need to be performed in the specific order described.

Claims

1. A method for repairing a hollow fan blade, the hollow fan blade comprising a first part and a second part fixed together by a coupling, the internal cavity of the hollow fan blade being filled with a vacuum, the method comprising: Determine the minimum safe distance from the joint; Remove material from the damaged portion of the leading edge of the hollow fan blade to at least the minimum safe distance from the joint; The damaged portion is welded so that the temperature of the joint does not exceed the deformation temperature; as well as During the welding process, a cooling system is used to cool the blades to maintain the temperature of the joint below the deformation temperature, thereby maintaining the vacuum of the internal cavity; the cooling system includes at least one of a copper block and a water-cooled block.

2. The method of claim 1, further comprising arranging a thermocouple on at least one of the first portion and the second portion.

3. The method of claim 2, further comprising using the thermocouple to monitor the temperature of a portion of the hollow fan blade during the welding process.

4. The method of claim 1, further comprising arranging a plurality of thermocouples on each of the first portion and the second portion.

5. The method of claim 4, further comprising using at least one item selected from the group consisting of spot welding and adhesives to arrange each of the plurality of thermocouples.

6. The method according to claim 1, the method further comprising fixing the hollow fan blades in a cleaning box prior to the welding.

7. The method of claim 1, further comprising arranging a gas pad for dispersing an inert gas during the welding process on at least one of the first portion and the second portion.

8. The method according to claim 1, wherein, The welding includes tungsten inert gas welding.

9. The method according to claim 1, wherein, The internal cavity further includes a honeycomb structure.

10. The method of claim 1, further comprising applying a finishing process after the welding.

11. The method according to claim 1, wherein, The joint includes a brazed joint.

12. A system for repairing hollow fan blades, the hollow fan blades comprising a first portion and a second portion fixed together by a coupling, the internal cavity of the hollow fan blades being filled with a vacuum, the system comprising: A welding substrate, defined on the surface formed after material is removed from the damaged portion of the leading edge of the hollow fan blade, and spaced at least a minimum safe distance from the joint; A cleaning box having mounting parts for fixing the hollow fan blades; as well as A temperature sensor configured to monitor the temperature of the hollow fan blades during welding; as well as A cooling system that cools the blades during the welding process to maintain the temperature of the joint below the deformation temperature, thereby maintaining the vacuum of the internal cavity; the cooling system includes at least one of a copper block and a water-cooled block.

13. The system of claim 12, further comprising a cooling system configured to cool the first and second portions of the blade during the welding process.

14. The system of claim 12, further comprising at least one gas pad disposed on at least one of the first portion and the second portion for dispersing an inert gas during the welding process.

15. The system according to claim 12, wherein, The hollow fan blades further include a honeycomb structure within the internal cavity.

16. A method for repairing a hollow fan blade, the hollow fan blade comprising a concave portion and a convex portion fixed together by a coupling, the internal cavity of the hollow fan blade being filled with a vacuum, the method comprising: Determine the minimum safe distance from the joint; Remove material from the damaged portion of the hollow fan blades to at least the minimum safe distance from the joint; as well as The damaged portion is welded so that the temperature of the joint does not exceed the deformation temperature; as well as During the welding process, a cooling system is used to cool the blades to maintain the temperature of the joint below the deformation temperature, thereby maintaining the vacuum of the internal cavity; the cooling system includes at least one of a copper block and a water-cooled block.

17. The method of claim 16, further comprising using a temperature sensor to monitor the temperature of the joint during the welding process.

18. The method of claim 16, further comprising distributing at least one gas pad near the joint on at least one of the concave portion and the convex portion for dispersing inert gas during the welding process.

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