A method for repairing the size of a turbine combustor outer band mating surface

Abstract

This invention discloses a method for repairing the dimensions of mating surfaces of an aero-engine combustor outer sleeve, comprising: cleaning and drying the mating surfaces after cutting; protecting the non-mating surface areas of the combustor outer sleeve and then sandblasting the mating surface areas; drying NiAl powder and NiCrW powder; sequentially spraying a base layer and a top layer onto the mating surfaces using plasma equipment, wherein the base layer is sprayed with NiAl powder multiple times until the base layer thickness is 0.25 mm to 0.3 mm, and the top layer is sprayed with NiCrW powder multiple times until the base layer thickness is 0.5 mm to 0.7 mm; machining the sprayed combustor outer sleeve mating surfaces until the diameter of mating surface A is 793.86 mm to 799.86 mm and the diameter of mating surface B is 852.77 mm to 854.77 mm. This invention restores the dimensions of worn surfaces through machining and thermal spraying, shortening the process to only 6 steps and reducing the repair cycle; the use of NiAl powder and NiCrW powder thermal spraying to form a coating on the mating surfaces of the combustor outer sleeve improves the performance of the combustor outer sleeve.

Description

Technical Field

[0001] This invention belongs to the field of combustion chamber outer sleeve mating surface dimension repair technology, specifically relating to a method for repairing the dimensions of the mating surface of an aero-engine combustion chamber outer sleeve. Background Technology

[0002] During engine operation, the alternating load transmitted by the rotating blades causes uneven wear on the mating surfaces A and B of the outer combustion chamber sleeve and the guide vane casing. This leads to a decrease in airtightness and affects engine performance. Furthermore, once the dimensions of this part are out of tolerance, it must be taken out of service and replaced with a new part or repaired by welding before it can be installed in the engine. This is not conducive to improving maintenance capacity and ensuring the smooth progress of maintenance work.

[0003] To avoid affecting the use of the parts, the existing combustion chamber outer sleeve mating surfaces are repaired using argon arc welding. This repair process involves 15 steps, as follows:

[0004] Parts receiving - runout inspection - machining - cleaning - pre-weld heat treatment - protection - argon arc welding - post-weld heat treatment - post-weld shaping - machining - fluorescent flaw detection - X-ray inspection - runout inspection - dimensional measurement - inspection and acceptance.

[0005] However, the existing process for repairing the mating surfaces of the combustion chamber outer casing is complex and has a long repair cycle. Summary of the Invention

[0006] To address the issues of complex methods and long repair cycles associated with the existing argon arc welding repair of the combustion chamber outer sleeve mating surfaces, this invention provides a method for repairing the dimensions of the combustion chamber outer sleeve mating surfaces of aero-engines, which reduces the number of repair steps and shortens the repair cycle.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] This invention discloses a method for repairing the dimensions of the mating surface of the outer casing of an aero-engine combustion chamber, comprising the following steps:

[0009] Place the outer casing of the combustion chamber on the platform of the five-axis machining center for fixation and centering. Adjust the tool to align with the mating surface of the outer casing of the combustion chamber. Cut the worn part of the mating surface flat until the size of the mating surface is greater than the minimum value required by the standard.

[0010] Clean and dry the mating surfaces after cutting;

[0011] After protecting the non-mating surface area of ​​the outer casing of the combustion chamber, the mating surface area is sandblasted until the mating surface area is uniformly gray and the surface roughness is 2.0μm to 4.8μm;

[0012] NiAl powder and NiCrW powder were dried at a temperature of 40℃~80℃ for a time of more than 30min.

[0013] The mating surfaces were sequentially coated with a base layer and a top layer using a plasma device. The base layer was coated with NiAl powder multiple times until the thickness of the base layer was 0.25 mm to 0.3 mm. The top layer was coated with NiCrW powder multiple times until the thickness of the base layer was 0.5 mm to 0.7 mm.

[0014] The mating surfaces of the outer casing of the combustion chamber after spraying are machined until the diameter of mating surface A is 793.86 mm to 799.86 mm and the diameter of mating surface B is 852.77 mm to 854.77 mm.

[0015] Compared with the prior art, the present invention has at least the following advantages and beneficial effects:

[0016] This invention restores the dimensions of worn surfaces through machining and thermal spraying, reducing the process to only 6 steps and shortening the repair cycle; it also uses NiAl powder and NiCrW powder thermal spraying to form a coating on the mating surface of the combustion chamber outer sleeve, improving the performance of the combustion chamber outer sleeve. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the outer casing of the combustion chamber. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0025] This invention discloses a method for repairing the dimensions of the mating surfaces of an aero-engine combustor outer sleeve. The method restores the dimensions of the worn surface through machining and thermal spraying, reducing the process to only six steps and shortening the repair cycle. A coating of NiAl powder and NiCrW powder is formed on the mating surfaces of the combustor outer sleeve using thermal spraying, improving the performance of the combustor outer sleeve. Specifically, the repair method includes steps S01 to S06. It should be noted that the step identifiers in this solution are only for ease of explanation and do not constitute a limitation on the order of steps. The order of each step is based on its verbal description and the sequential connection of each signal.

[0026] Step S01: Place the outer combustion chamber sleeve on the five-axis machining center platform for fixation and centering. Adjust the tool to align with the mating surface of the outer combustion chamber sleeve. Cut the worn area of ​​the mating surface flat until the mating surface size is greater than the minimum standard requirement.

[0027] The structural schematic diagram of the outer casing 1 of the combustion chamber is as follows: Figure 1As shown, its mating surfaces include mating surface A 11 and mating surface B 12.

[0028] During cutting, align mating surfaces A (11) and B (12) with the cutting tool for cutting. The machining dimension is 0.3 mm to 0.5 mm, and the single feed rate is 0.05 mm. The inner diameter of mating surface A is less than or equal to 794.86 mm, and the inner diameter of mating surface B is less than or equal to 849.77 mm.

[0029] Step S02: Clean and dry the mating surfaces after cutting.

[0030] In this step, acetone is used to clean the mating surfaces to ensure that there are no residual metal shavings, oil stains, etc. in the machined area. After cleaning, the surfaces can be left to air dry at room temperature or wiped dry with a clean white cloth.

[0031] Step S03: After protecting the non-mating surface area of ​​the outer casing of the combustion chamber, the mating surface area is sandblasted until the mating surface area is uniformly gray and the surface roughness is 2.0μm to 4.8μm.

[0032] This step only requires sandblasting of the mating surface area; therefore, the non-mating surfaces must first be protected. Specifically, pressure-sensitive adhesive tape can be used to protect the non-mating surfaces.

[0033] When sandblasting the mating surface area, use 120-mesh white corundum sand, control the compressed air pressure to be 0.15 MPa to 0.35 MPa, the sandblasting distance to be 100 mm to 150 mm, and the sandblasting angle to be 75° to 90°, and sandblast until the surface of the part is uniformly gray.

[0034] All mating surfaces should be sandblasted. A qualified sandblasted surface should have a uniformly rough surface and should not have surface contaminants such as rust, spots, dirt, scale, oil, or fingerprints that could affect the coating quality. The surface roughness of the mating surfaces after sandblasting should be 2.0μm to 4.8μm to ensure the coating quality during subsequent spraying.

[0035] Step S04: Dry the NiAl powder and NiCrW powder at a temperature of 40℃~80℃ for a time of more than 30 min.

[0036] Before spraying, NiAl powder and NiCrW powder are dried to improve the spraying quality.

[0037] Specifically, a clean powder drying box or a powder container can be placed in a drying oven to dry NiAl powder and NiCrW powder.

[0038] Step S05: The mating surfaces are sequentially coated with a base layer and a top layer using a plasma device. The base layer 13 is coated with NiAl powder multiple times until the thickness of the base layer is 0.25 mm to 0.3 mm. The top layer 14 is coated with NiCrW powder multiple times until the thickness of the base layer is 0.5 mm to 0.7 mm.

[0039] In this step, the base layer and the top layer are made of NiAl powder and NiCrW powder, respectively. When spraying the NiAl powder base layer, the current is 550±10V, the voltage is 40±5A, the spraying distance is 100±10mm, and 18 to 22 coats are applied until the base layer thickness is 0.25 mm to 0.3 mm.

[0040] When applying NiCrW powder coating to the top layer, the current is 380±10V, the voltage is 35±5A, the spraying distance is 100±10mm, and 18 to 22 coats are applied until the base layer thickness is 0.5 mm to 0.7 mm.

[0041] The bottom layer is formed by NiAl powder spraying, which serves as an intermediate adhesive layer. This allows the substrate and the wear-resistant layer to be firmly connected, preventing the surface layer from directly bonding to the substrate and causing detachment due to poor adhesion.

[0042] The surface layer uses NiCrW powder, which is a wear-resistant coating that effectively improves the wear resistance of the mating surfaces of the parts and reduces the probability of the parts being damaged by impact again during use.

[0043] After spraying, visually inspect the coating surface to ensure it is flat, dense, and uniform in color, without defects such as cracks, delamination, peeling, or edge lifting.

[0044] Step S06: Machin the mating surfaces of the outer casing of the combustion chamber after spraying until the diameter of mating surface A is 793.86 mm to 799.86 mm and the diameter of mating surface B is 852.77 mm to 854.77 mm.

[0045] During machining, the machining dimension is 0.25 mm to 0.7 mm, and the single feed rate is 0.05 mm to improve the repair quality.

[0046] The method described in this scheme restores the dimensions of the worn surface through machining and thermal spraying, shortening the modification cycle. During the spraying process, the performance of the coating is improved by studying the current, voltage, and spraying distance.

[0047] The method described in this solution removes the worn areas of mating surfaces A and B while minimizing damage to the substrate. This prevents the parts from deforming due to excessive damage to the substrate and ensures that the subsequent coating thickness is neither too thin nor too thick, thus meeting the usage requirements under engine operating conditions.

[0048] The method proposed in this solution allows the repaired combustion chamber sleeve to meet the installation requirements. Compared with welding repair, spraying reduces repair procedures, improves production efficiency, reduces parts procurement costs, and facilitates maintenance and support work.

[0049] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for repairing the dimensions of the mating surface of the outer casing of an aero-engine combustion chamber, characterized in that, Includes the following steps: Place the outer casing of the combustion chamber on the platform of the five-axis machining center for fixation and centering. Adjust the tool to align with the mating surface of the outer casing of the combustion chamber. Cut the worn part of the mating surface flat until the size of the mating surface is greater than the minimum value required by the standard. Clean and dry the mating surfaces after cutting; After protecting the non-mating surface area of ​​the outer casing of the combustion chamber, the mating surface area is sandblasted until the mating surface area is a uniform gray color and the surface roughness is 2.0μm~4.8μm; NiAl powder and NiCrW powder were dried at a temperature of 40℃~80℃ for a time of more than 30min. The mating surfaces are sequentially coated with a base layer and a top layer using a plasma device. The base layer is coated with NiAl powder multiple times until the thickness is 0.25mm to 0.3mm, and the top layer is coated with NiCrW powder multiple times until the thickness is 0.5mm to 0.7mm. The mating surfaces of the outer casing of the combustion chamber after spraying are machined until the diameter of mating surface A is 793.86mm~799.86mm and the diameter of mating surface B is 852.77mm~854.77mm. The process involves cutting and smoothing the worn areas of the mating surfaces until the mating surface dimensions are greater than the minimum standard requirement. Cut the worn area of ​​the mating surface with a machining dimension of 0.3mm to 0.5mm and a single feed rate of 0.05mm until the inner diameter of mating surface A is less than or equal to 794.86mm and the inner diameter of mating surface B is less than or equal to 849.77mm. The cleaning of the mating surfaces after cutting is as follows: The mating surfaces were cleaned with acetone. When sandblasting the mating surface area after protecting the non-mating surface area of ​​the outer casing of the combustion chamber, 120-mesh white corundum sand is used, and the compressed air pressure is controlled at 0.15MPa~0.35MPa, the sandblasting distance is 100mm~150mm, and the sandblasting angle is 75°~90°. The underlying layer is coated with NiAl powder multiple times until the thickness of the underlying layer is 0.25mm to 0.3mm, including: NiAl powder was sprayed 18 to 22 times at a current of 550±10V, a voltage of 40±5A, and a spraying distance of 100±10mm to form a base layer with a thickness of 0.25mm to 0.3mm. The surface layer is coated multiple times with NiCrW powder until the thickness of the base layer is 0.5mm to 0.7mm, including: NiCrW powder was sprayed 18 to 22 times at a current of 380±10V, a voltage of 35±5A, and a spraying distance of 100±10mm to form a surface layer with a thickness of 0.5mm to 0.7mm. When machining the mating surface of the outer casing of the combustion chamber after spraying, the machining size is 0.25mm to 0.7mm, and the single feed rate is 0.05mm.

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