Method for repairing aero-engine compressor blade damage on site

Abstract

The application discloses an aero-engine compressor blade damage on-site repair method in the technical field of compressor blade damage repair, adopts any one or a combination of two of the repair methods of the repair method or the symmetric shearing method, removes the damage on the blade without disassembling the blade disc, reduces the influence of the damage on the compressor performance, simultaneously prevents the damage from further expanding, and the repaired blade disc can continue to be used, increases the service life of the blade disc, and guarantees the safety during the use of the blade disc.

Description

Technical Field

[0001] This invention relates to the field of compressor blade damage repair technology, specifically to on-site repair methods for damaged aero-engine compressor blades. Background Technology

[0002] Aircraft engines operate in complex environments, including sandy areas, rainforests, and high-altitude cold regions, and compressor blade disk damage is a frequent occurrence. Currently, the repair method for this type of failure is to return the engine to the factory for disassembly and replacement of the compressor blade disk, which typically takes 3 to 12 months.

[0003] Traditionally, damaged compressor blades can only be replaced at the factory, without any repair. This results in a large number of scrapped parts every year, leading to a waste of resources. Furthermore, the long repair cycle at the factory can affect the overall combat effectiveness of aviation equipment. To effectively shorten the repair cycle of this fault and minimize the impact on the training capabilities of the troops, it is extremely important to develop a method for repairing compressor blade disk damage in the condition of the entire aircraft.

[0004] Based on this, the present invention designs an on-site repair method for damaged aero-engine compressor blades to solve the above problems. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for on-site repair of damaged compressor blades in aero-engines, characterized by comprising the following steps:

[0006] Step 1: Determine the permissible damage range of the blades based on the blade type;

[0007] Step 2: Determine the type and location of leaf damage;

[0008] Step 3: Based on the type of damage, select either the polishing method or the symmetrical shearing method, or a combination of both, for repair.

[0009] The polishing method involves smoothing out the damaged area at the leading edge of the blade.

[0010] The symmetrical shearing method involves cutting away the damaged area of ​​the blade and then cutting the blade at the same angle and position symmetrical to the already cut blade.

[0011] Step 4: Blade reassembly and test run.

[0012] As a further aspect of the present invention, in step 2, the method for determining the blade damage type, damage location, and size is as follows:

[0013] S21, a borescope is used to detect the type, area and size of blade damage;

[0014] S22, Remove the external parts of the engine to expose the internal blade disk, and use measuring tools to measure the damage to the blades in the damaged area to obtain the precise location of the damage.

[0015] As a further aspect of the present invention, the measuring tool includes a conforming gauge, which includes a conforming end that matches the shape of the blade for fitting against the blade and a handle for gripping.

[0016] As a further aspect of the present invention, in step 3, if the damage type is blade leading edge depression, crack, or corrosion notch damage, then a polishing repair method is adopted. The polishing repair method steps are as follows:

[0017] S411 uses a support clamp to clamp the rotor, numbers the entire disc of blades, records damaged blades, and controls foreign matter in the engine.

[0018] S412, Use a profile gauge to mark the depth D and width W of the damage that needs to be repaired;

[0019] S413, calculate the width and depth of the repair area based on the width-to-depth ratio W / D≥3 to ensure the repair range is minimized;

[0020] S414, use a file to polish the damaged area. When polishing the damaged area, first grind the highest point of the leading edge of the leaf along the tangent of the leaf back and leaf basin to ensure that the width and depth of the mark are polished in place, and repair the damaged area into a U-shape.

[0021] S415: Use metallographic sandpaper to wrap around a precision mixed file and a round file 2 to 3 times to polish the inside and edges of the damaged area.

[0022] As a further aspect of the present invention, in step 3, if the damage type is leaf tip curling or leaf tip damage, a symmetrical shearing method is used. The steps of the symmetrical shearing method are as follows:

[0023] S421, clamps the rotor with a support fixture, numbers the entire disc of blades, records damaged blades, and controls foreign matter in the engine;

[0024] S422, for cutting the leading edge of the blade, use a profile gauge to mark the transition point between the blade tip and the leading edge on the blade. Draw a line along the marked point. The line and the damaged blade tip are the areas to be cut.

[0025] For leaves with tip damage, mark the damaged area at any angle in the tip corner area to ensure the minimum cutting range, and then measure the length of the mark line.

[0026] S423, Use sheet metal pliers to cut the blade along the outside of the marked line;

[0027] S424: Use metallographic sandpaper to wrap around a precision assorted file and a round file 2 to 3 times to smoothly polish the shearing part of the blade;

[0028] S425, rotate the blade disk 180 degrees, find the symmetrical blade, and repeat S422 to S424 above to cut the symmetrical blade.

[0029] As a further aspect of the present invention, the method for controlling excess material is as follows:

[0030] S31, after the right half of the compressor casing is separated, use oil-absorbing paper to completely cover the mating surface between the compressor casing and the front section.

[0031] S32, use tape to tightly seal the gear hub clearance at the blade disk end;

[0032] S33, use tape to firmly attach the blade to the blade body and back except for the part to be repaired for protection;

[0033] S34, Use tape to wrap the blades around the blade to be repaired for protection;

[0034] S35, place oil-absorbing paper directly below the repair blade.

[0035] The present invention has the following beneficial effects:

[0036] This method offers various solutions for different types and locations of damage to compressor blade disks. When dents, cracks, and corrosion damage appear on the leading edge of the blade, a polishing method is used to polish the damaged area into a U-shape, transitioning it with the rounded edge of the blade leading edge. This reduces the impact of the damage on performance and stability during blade rotation and prevents further expansion of the damage. When the blade leading edge is curled or the blade tip is damaged, a symmetrical shearing method is used to remove the curled blade or damaged blade tip. Blades symmetrical to the sheared blade are sheared at the same angle and position to minimize the impact of the damage on compressor performance, reduce flow loss, prevent further expansion of blade damage, and ensure dynamic balance during blade disk rotation. This method removes damage to the blades without disassembling the blade disk, reducing the impact of blade damage on compressor performance and preventing further expansion of damage. The repaired blade disk can continue to be used, increasing its service life and ensuring safety during operation.

[0037] In addition to the objectives, features, and advantages described above, the present invention has other objectives, features, and advantages. The invention will now be described in further detail with reference to the figures. Attached Figure Description

[0038] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0039] Figure 1 This is a schematic diagram of the process of the present invention;

[0040] Figure 2 This is a schematic diagram of the overall process of the present invention;

[0041] Figure 3 A schematic diagram for confirming the permissible damage range of the blade;

[0042] Figure 4 This is a top view of the blade structure.

[0043] Figure 5 This is a schematic diagram of the horizontal cross-sectional structure of the damaged area after repair by the polishing method;

[0044] Figure 6 A schematic diagram of the measurement of leading edge curling of the blade;

[0045] Figure 7 This is a schematic diagram of the profile gauge.

[0046] Figure 8 This is a schematic diagram of the blade tip shear structure;

[0047] Figure 9 This is a schematic diagram of the support fixture structure. Detailed Implementation

[0048] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0049] Please see Figure 1-9 This invention provides a technical solution: a method for on-site repair of damaged aero-engine compressor blades, which removes damage from engine blades and reduces the impact of damaged blades on the performance of the engine compressor, including the following steps:

[0050] Step 1: Determine the permissible damage range of the blades based on the blade type;

[0051] Specifically, this step is the preliminary preparation work for blade repair. Depending on the size, function, and material of the blade, the permissible damage range varies. Consult the technical manual to determine the maximum remaining chord length that must be retained at the blade root and tip positions. Figure 3 As shown, starting from the trailing edge of the leaf, points are plotted according to the chord length that needs to be preserved. Finally, the two points at the leaf tip and leaf root are connected to the trailing edge to form the area that must be preserved. Damage outside this area is repairable damage.

[0052] Step 2: Determine the type and location of leaf damage;

[0053] Specifically, after confirming the permissible damage range of the blade, the next step is to determine whether the current damage is within the permissible damage range. First, a borescope is used to detect the type, area, and size of the blade damage, and to observe whether the damage on the blade significantly exceeds the permissible damage range. Next, the engine is disassembled to expose the blade disk. When the damage significantly exceeds the maximum permissible damage, it means that the blade cannot be repaired on-site and the entire blade disk needs to be disassembled and returned to the factory for replacement. When the blade damage does not significantly exceed the permissible damage range, a contour gauge is used for the next step of precise measurement to determine the precise location of the blade damage and to mark the permissible damage range of the blade.

[0054] like Figure 7 As shown, the profile gauge consists of a profile end and a handle. The profile end matches the shape of the blade and has graduations on its surface to fit against the blade surface, facilitating precise scribing on the twisted surface of the blade.

[0055] Step 3: Based on the type of damage, select either the polishing method or the symmetrical shearing method, or a combination of both, for repair.

[0056] Different repair solutions are selected based on the actual type and location of the damage, and the optimal repair solution is identified to save manpower and resources.

[0057] The polishing method involves smoothing out the damaged area at the leading edge of the blade.

[0058] This step is a method for on-site repair of damage such as dents, cracks and corrosion on the leading edge of the blade. By polishing the damaged area to make the inside of the damage U-shaped, and at the same time making the damaged area smooth transition with the normal surface of the blade, the impact of the damage on the performance and stability during the blade rotation is reduced, and the damage is prevented from expanding further.

[0059] Specifically, such as Figure 8 As shown, firstly, the rotor is clamped using a support fixture, and all blades on the disc are numbered, with damaged blades recorded. Next, a profile gauge is used to determine the depth D and width W of the damage requiring polishing. The depth D and width W of the damage are marked on the blade. While ensuring the repair area is minimized, the width and depth after repair are calculated according to the requirement of W / D≥3, and marked at the corresponding positions on the blade. W / D≥3 can prevent stress concentration in the damaged area. A file is used to polish the damaged area. When polishing the damaged area, the highest point of the damaged area on the leading edge of the blade is ground along the tangent of the blade back and blade base, ensuring that the marked width and depth are properly polished. The repaired damaged area is U-shaped. Next, metallographic sandpaper is wrapped around a precision assorted file and a round file 2 to 3 times, and the leading edge surface of the blade is smoothly polished along the tangential direction of the blade back and parallel to the chord length. Figure 3-5 As shown, the damaged area is made smooth inside, and the damaged area is also smoothly transitioned to the front edge, reducing the flow loss of the blade when it is working after repair.

[0060] The symmetrical shearing method involves cutting away the damaged area of ​​the leaf and then cutting the leaf at the same angle and position symmetrical to the already cut leaf.

[0061] This step is an on-site repair method for blade leading edge curling and blade tip damage. By cutting the blade leading edge curling and blade tip damage, the impact of damage on compressor performance is reduced, flow loss is reduced, and blade damage is prevented from further expanding. At the same time, blades symmetrical to the cut blades are cut at the same angle and position to ensure dynamic balance during blade disk rotation.

[0062] Specifically, the rotor is first clamped with a support fixture, the blades of the entire disc are numbered, and the damaged blades are recorded. The next steps vary depending on the location of the damage.

[0063] When shearing a blade with a curled leading edge, the guide gauge may not be able to fit snugly due to the curled leading edge. Figure 6 As shown, a profile gauge is used to closely follow the blade from the other side of the blade's leading edge bending direction. The points where the gap between the blade tip and the profile gauge, as well as between the leading edge and the profile gauge, are marked on the blade. A line is drawn along the marked points, and the line and the damaged blade tip are the areas to be cut.

[0064] When cutting leaves with tip damage, mark the damaged area at any angle in the tip region to minimize the cutting range. Then measure the length of the mark. The leaf tip area has specific requirements for the permissible damage range, such as... Figure 8 As shown, the shear line length at the blade tip should not exceed C. C varies depending on the blade model, function, and material. When both the leading and trailing edges of the blade tip are damaged, the sum of the shear line lengths of the two blade tips should not exceed C.

[0065] Next, use sheet metal pliers to cut the blades along the outside of the marked lines. After cutting, wrap metallographic sandpaper around a precision assorted file and a round file 2 to 3 times to smooth and polish the cut part of the blades, reducing flow loss during blade operation. Finally, rotate the blade disk 180 degrees to find symmetrical blades and repeat the above steps to cut symmetrical blades.

[0066] Step 4: Blade reassembly and test run;

[0067] This step is the inspection step after the repair of the blade. The blade disk is reinstalled on the engine to check the compressor performance and dynamic balance.

[0068] When using the polishing and symmetrical shearing methods to repair blades, the following preparatory work needs to be carried out.

[0069] S1. After the right half of the compressor casing is separated, use oil-absorbing paper to completely cover the mating surface between the compressor casing and the front section to prevent debris from flying into the front section during shearing and polishing.

[0070] S2, use tape to seal the gap between the blade disk end and the gear hub to prevent debris from entering;

[0071] S3. Use tape to firmly attach the blade to the underside of the leaf, except for the part to be repaired, to protect it and prevent damage to the leaf during the pruning process.

[0072] S4. Use tape to wrap the blades around the blade to be repaired to protect them from accidental damage to the surrounding blades when repairing the blade with a file.

[0073] S5: Place absorbent paper directly below the repair blade to collect metal shavings and prevent them from falling into the engine.

[0074] like Figure 2 As shown, the overall process steps are as follows:

[0075] A borescope is used to inspect the blades for damage. If no damage is found, the blades continue to be used. If damage is detected, the location of the damage is used to determine if it is significantly beyond the acceptable range. If it is significantly beyond the acceptable range, the blades are returned to the factory for repair. If the damage is not significantly beyond the acceptable range, the next step is to disassemble and inspect the engine. The disassembly steps are: disassembly of external cables, pump regulator, no-load starter, ignition device, and external piping. At this point, the compressor is exposed. Next, the right half of the compressor casing is disassembled. After disassembly, the support clamp is fixed to the compressor casing that has not been disassembled. The rotor is clamped with the support clamp. After the rotor is fixed, the precise location and size of the damage are determined using a profile gauge to confirm whether on-site repair is possible. If on-site repair is not suitable, the entire compressor is removed and returned to the factory for repair. If on-site repair is possible, excess equipment on the engine is protected. Next, the blade leading edge damage, curling, and blade tip damage are repaired using the shovel repair method and symmetrical shearing method, respectively. After repair, the surface of the parts is cleaned and the engine is reassembled for a test run.

[0076] Example

[0077] The first-stage blade of a certain type of aero-engine barometer has a blade height of 49mm and a tip chord length of 40mm. According to the technical manual, the maximum remaining chord lengths that must be retained at the blade root and blade tip are 34.4mm and 38.0mm, respectively. The repair area cannot involve the critical 5.0mm area at the blade root. The maximum shear length C at the blade tip is 19mm. Using a contour gauge, points were marked at 38mm at the blade tip and 34.4mm at the blade root, starting from the trailing edge. The two points were then connected. The area to the left of the line is the repairable area. A dented damage was found at the leading edge of the dented area. The damage was measured to be 2.3mm wide and 0.7mm deep. After repair, the U-shaped damage was 2.5mm wide and 0.8mm deep.

[0078] Currently, the integral bladed disk has been reassembled and put into use.

[0079] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for on-site repair of damaged compressor blades in aero-engines, characterized in that, Includes the following steps: Step 1: Determine the permissible damage range of the blades based on the blade type; Step 2: Determine the type and location of leaf damage; Step 3: Based on the type of damage, select either the polishing method or the symmetrical shearing method, or a combination of both, for repair. The polishing method involves smoothing out the damaged area at the leading edge of the blade. The symmetrical shearing method involves cutting away the damaged area of ​​the blade and then cutting the blade at the same angle and position as the damaged area. Step 4: Blade reassembly and test run; In step 3, if the damage type is blade leading edge dent, crack, or corrosion notch damage, then the polishing repair method is adopted. The polishing repair method steps are as follows: S411 uses a support clamp to clamp the rotor, numbers the entire disc of blades, records damaged blades, and controls foreign matter in the engine. S412, Use a profile gauge to mark the depth D and width W of the damage that needs to be repaired; S413, calculate the width and depth of the repair area based on the width-to-depth ratio W / D≥3 to ensure the repair range is minimized; S414, use a file to polish the damaged area. When polishing the damaged area, first grind the highest point of the leading edge of the leaf along the tangent of the leaf back and leaf basin to ensure that the width and depth of the mark are polished in place, and repair the damaged area into a U-shape. S415: Use metallographic sandpaper to wrap around a precision assorted file and a round file 2 to 3 times to polish the inside and edges of the damaged area; In step 3, if the damage type is leaf tip curling or leaf tip damage, the symmetrical shearing method is used. The steps of the symmetrical shearing method are as follows: S421, clamps the rotor with a support fixture, numbers the entire disc of blades, records damaged blades, and controls foreign matter in the engine; S422, for cutting the leading edge of the blade, use a profile gauge to mark the transition point between the blade tip and the leading edge on the blade. Draw a line along the marked point. The line and the damaged blade tip are the areas to be cut. For leaves with tip damage, mark the damaged area at any angle in the tip corner area to ensure the minimum cutting range, and then measure the length of the mark line. S423, Use sheet metal pliers to cut the blade along the outside of the marked line; S424: Use metallographic sandpaper to wrap around a precision assorted file and a round file 2 to 3 times to smoothly polish the shearing part of the blade; S425, rotate the blade disk 180 degrees, find the symmetrical blade, and repeat S422 to S424 above to cut the symmetrical blade.

2. The on-site repair method for damaged aero-engine compressor blades according to claim 1, characterized in that, In step 2, the methods for determining the type, location, and size of blade damage are as follows: S21, a borescope is used to detect the type, area and size of blade damage; S22, Remove the external parts of the engine to expose the internal blade disk, and use measuring tools to measure the damage to the blades in the damaged area to obtain the precise location of the damage.

3. The on-site repair method for damaged aero-engine compressor blades according to claim 2, characterized in that, The measuring tool includes a profile gauge, which has a profile end that matches the shape of the blade for fitting against the blade and a handle for gripping.

4. The on-site repair method for damaged aero-engine compressor blades according to claim 1, characterized in that, The methods for controlling excess materials are as follows: S31, after the right half of the compressor casing is separated, use oil-absorbing paper to completely cover the mating surface between the compressor casing and the front section. S32, use tape to tightly seal the gear hub clearance at the blade disk end; S33, use tape to firmly attach the blade to the blade body and back except for the part to be repaired for protection; S34, wrap the blades around the blade to be repaired with tape for protection; S35, place oil-absorbing paper directly below the repair blade.

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