A method for machining blade size in a low-pressure stator assembly

Abstract

The present invention relates to a method for machining the blade size in a low-pressure stator assembly, comprising steps S1: adding layers to be turned at the upper and lower ends of the stator outer ring; S2: confirming the alignment of the blades, where Y is the theoretical value of the distance from the fixed point to the top of the stator outer ring; S3: using three alignment blades as reference surfaces, placing shims of different thicknesses under the B surface of the stator outer ring; S4: turning the A surface of the stator outer ring; S5: flipping the stator assembly over and turning the B surface of the stator outer ring; S6: flipping the stator assembly over again, pressing the stator assembly onto a machining platform, adjusting the feed rate, and turning the A surface again, ultimately controlling the height between the fixed point on the blade and the A surface to be within an acceptable range. By machining the stator assembly using this method, the blade size of the stator assembly after brazing is ensured to meet the requirements.

Description

Technical Field

[0001] The present invention relates to the field of aero engines, and more particularly to a method for machining blade sizes in a low-pressure stator assembly. Background Art

[0002] The low-pressure stator assembly of an existing aircraft engine is welded together from a 41-blade low-pressure stator outer ring (hereinafter referred to as the stator outer ring), a low-pressure stator inner ring (hereinafter referred to as the stator inner ring), and stator blades (hereinafter referred to as blades). The low-pressure stator outer ring and the low-pressure stator inner ring are connected to the 41 stator blades by brazing. Numerous welds occur at brazing temperatures approaching 1000°C, causing stress release in the stator assembly. This results in significant overall deformation of the stator assembly after brazing, ultimately leading to irregular deformation of the blades and the end faces of the stator outer ring mounting edge. This also causes fluctuations in the height of the blades from the stator outer ring mounting edge, ultimately resulting in dimensional deviations between the blades and the top of the stator outer ring.

[0003] The prior art CN117773075A discloses a method for processing a small blade of an aero-engine, comprising: S1: three points A1, A2, A3 of the upper edge plate of the blade and two points B4, B5 of the leading edge of the blade body and the edge plate flow channel surface point C6 form the six-point positioning position of the blade; the fixture is turned over and placed on the support block, and the six-point positioning position of the blade is held against the first six-point positioning position on the fixture; S2: the fixture and the blade are turned over together, and then the fixture is placed on the top of the first limit block and the second limit block, and the process convex of the blade is formed. The table extends into the casting box; S3: The casting box is fixed to the first base plate, and then the molten tin-bismuth alloy is poured into the casting box; the six-point positioning system on the blade is converted to the three reference positioning surfaces of the clamp for positioning; S4: The casting box is cooled; S5: The cooled casting box is removed from the casting device and fixed to the second six-point positioning position of the grinding device based on the three reference positioning surfaces of the clamp; S6: Two pressing plates are fixed to the top of the casting box, and then the blade is ground;

[0004] Although the prior art discloses a blade grinding method, it can only solve the problem of varying degrees of crushing of the blade body during the machining process, and cannot guarantee the size of the blade after brazing. Summary of the Invention

[0005] The invention provides a method for processing the blade size in a low-pressure stator assembly by processing the stator assembly after brazing so as to ensure the blade size.

[0006] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0007] Disclosed is a method for machining the blade size of a low-pressure stator assembly, which specifically comprises the following steps:

[0008] S1: Add layers to be turned at the upper and lower ends of the stator outer ring, and then weld the stator outer ring, stator inner ring and blades;

[0009] S2: Place the welded stator assembly on a horizontal platform and establish a coordinate system to obtain three blades with the same distance from the fixed point on the blade to the top of the stator outer ring as alignment blades. Y is the theoretical value of the distance from the fixed point to the top of the stator outer ring.

[0010] S3: Using the three alignment blades as reference planes, place shims of different thicknesses under the B surface of the stator outer ring;

[0011] S4: Turning the A surface of the stator outer ring;

[0012] S5: Turn over the stator assembly and turn the B surface of the stator outer ring;

[0013] S6: Flip the stator assembly again, press the stator assembly on the processing platform, adjust the feed amount and turn the A surface again, and finally control the height between the fixed point on the blade and the A surface to be within the qualified range.

[0014] Preferably, in step S2, the number of interval blades between the three alignment blades is greater than eight.

[0015] Preferably, in step S3, shims of different thicknesses are placed according to the flatness of the B surface of the stator outer ring, thereby ensuring that the corresponding fixing points on the three alignment blades are in the same horizontal plane.

[0016] Preferably, the step S4 further includes testing the flatness of the B surface of the stator outer ring after turning, and the flatness is controlled within 0.04 mm.

[0017] Preferably, in step S6, the flatness of surface A after further turning is controlled within 0.05 mm.

[0018] Preferably, in step S6, the feed amount is calculated by finding the maximum and minimum values ​​of the blade height of the end face during the first turning.

[0019] Preferably, the feed amount C=the average value of the sum of the maximum value and the minimum value minus Y.

[0020] Preferably, the fixed point is the intersection of a circle with a radius of 160 mm and the blade, with the center of the stator assembly as the center.

[0021] Preferably, in step S2, marking is performed on the alignment blade using a marking pen.

[0022] Preferably, in step S5, the B surface is parallel to the A surface after turning.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. Add layers to be turned at both ends of the stator outer ring, and use three blades as alignment blades to turn the A and B surfaces of the stator outer ring respectively, so as to obtain the height dimensions of the fixed point on the blade and the A surface of the stator outer ring, and turn the A surface again to finally ensure that the dimensions of the blade fixing point and the A surface of the stator outer ring are within the qualified range.

[0025] 2. By increasing the layer to be turned, the thickness of the stator outer ring is increased, the turning size of the stator outer ring is increased, and the operability is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of a method for machining blade size in a low-pressure stator assembly according to the present invention;

[0027] Figure 2 A structural diagram of a stator assembly in a method for machining blade size in a low-pressure stator assembly according to the present invention;

[0028] Figure 3 A turning surface diagram of a method for machining the blade size of a low-pressure stator assembly according to the present invention;

[0029] Figure 4 This is a diagram defining the H2 dimension in a method for machining the blade dimensions of a low-pressure stator assembly according to the present invention;

[0030] Figure 5 This is a diagram defining the H4 dimension in a method for machining blade dimensions in a low-pressure stator assembly according to the present invention. DETAILED DESCRIPTION

[0031] In order to clearly illustrate the technical features of this solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings.

[0032] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present application is not limited to the specific embodiments disclosed below.

[0033] In addition, in the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0034] In this application, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0035] In this application, unless otherwise expressly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0036] Example 1

[0037] like Figures 1 to 3 As shown, a method for machining the blade size in a low-pressure stator assembly is disclosed, which specifically includes the following steps:

[0038] S1: adding layers to be turned at the upper and lower ends of the stator outer ring 1, and then welding the stator outer ring 1, the stator inner ring 2 and the blades 3;

[0039] S2: Place the welded stator assembly on a horizontal platform, and establish a coordinate system to obtain three blades 3 with the same distance from the fixed point on the blade 3 to the top of the stator outer ring 1 as alignment blades. Y is the theoretical value of the distance from the fixed point to the top of the stator outer ring 1.

[0040] S3: Using the three alignment blades as reference surfaces, place shims of different thicknesses under the B surface of the stator outer ring 1;

[0041] S4: Turning the A surface of the stator outer ring 1;

[0042] S5: Turn over the stator assembly and turn the B surface of the stator outer ring 1;

[0043] S6: Flip the stator assembly again, press the stator assembly onto the machining platform, adjust the feed rate and turn the A surface again, and finally control the height between the fixed point on the blade 3 and the A surface to be within the qualified range.

[0044] In this embodiment, the top of the stator outer ring 1 is surface A, and the bottom is surface B. The size of the blade 3 refers to the height difference between the blade 3 and the top of the stator outer ring 1, i.e., surface A. Because the top of the blade 3 is curved, the blade 3 size is measured at the same point on the top of different blades 3. Specifically, the intersection of a circle with a radius of 160 mm, centered at the center of the stator assembly, and the blade 3 is the fixed point. This fixed point ensures the accuracy of blade 3 size measurement.

[0045] To ensure the proper dimensions of the blades 3, the stator outer ring 1 is dimensioned before brazing the stator assembly. Specifically, a 1mm thick pre-turning layer is added to each end of the stator outer ring 1, namely, on the A and B surfaces. The purpose of this pre-turning layer is to provide a margin for machining during subsequent turning without changing the stator outer ring 1's dimensions.

[0046] Place the stator assembly on the vertical lathe turntable, press the stator assembly lightly to center the stator assembly, then turn the turntable, place the dial indicator probe on the three marked fixed points of blade 3, press the needle to 0, observe the value displayed on the machine tool panel, and repeat the dial indicator operation on the remaining two marked blades 3. During the calibration process, continuously insert gaskets of different thicknesses on the B side until the numerical difference of the three marked blades 3 on the machine tool panel is within 0.05, then tighten the bolts, tighten the stator assembly, and then recheck whether the numerical difference of the three marked blades 3 on the machine tool panel is within 0.05. If it exceeds the 0.05 range, repeat the above calibration operation. If it meets the requirements, the calibration of the blade 3 plane is completed.

[0047] The brazed stator assembly is placed on a machining platform, and a coordinate system is established to determine the actual dimensions of each blade 3. This yields at least three blades 3 with dimensions within the range Y+1 mm, where Y is the theoretical distance from the fixed point to the top of the stator outer ring 1.

[0048] The three blades 3 are used for alignment. Three fixed points on the three blades form a reference plane. This reference plane is parallel to the horizontal plane. At this point, shims of varying thickness are placed on the bottom of surface B of the stator outer ring 1. These shims ensure stability between the stator assembly and the machining platform, preventing shaking during turning.

[0049] At this time, the bottom of the stator outer ring 1 is fixed, and then the A surface of the stator outer ring 1 is turned, with a specific turning amount of 0.2 mm, thereby completing the rough processing of the A surface. The purpose of the rough processing of the A surface is mainly to ensure that the A surface is flat after rough processing.

[0050] The stator assembly is flipped 180°, with surface A now aligned with the machining platform. The stator assembly is fixed again, and surface B is turned with a turning depth of 0.2 mm.

[0051] Turn the stator assembly over again, fix the stator assembly on the processing platform, adjust the feed amount of the turning equipment, and turn the A surface again.

[0052] The layers to be turned are added at both ends of the stator outer ring 1, and the three blades 3 are used as alignment blades to turn the A and B surfaces of the stator outer ring respectively, so as to obtain the height dimensions of the fixed point on the blade 3 and the A surface of the stator outer ring, and finally ensure that the dimensions of the fixed point of the blade 3 and the A surface of the stator outer ring are within the qualified range. Abandon the traditional method of blindly processing the blade height under the condition of uncertain blade plane and machining allowance, which leads to the problem of not being able to guarantee the blade height. By measuring the blade height in advance, the three blades with heights in the median range are aligned according to the measurement results before machining, and the blade plane is straightened. By leveling, the blade height plane is realigned. The difference between the blade height measured after rough machining of the A surface and the theoretical size is used to machine the B surface, and the end face flatness is better, which provides a reference plane for the subsequent fine machining process and ensures the final blade height. The present invention also provides another machining method for adjusting the machining height of the stator assembly in the middle process, offsetting the excess value of the blade height in the previous process, and directly ensuring the blade height in the process of machining the total height of the stator assembly.

[0053] Example 2

[0054] Disclosed is a method for machining the blade size of a low-pressure stator assembly, which specifically comprises the following steps:

[0055] S1: adding layers to be turned at the upper and lower ends of the stator outer ring 1, and then welding the stator outer ring 1, the stator inner ring 2 and the blades 3;

[0056] S2: Place the welded stator assembly on a horizontal platform, and establish a coordinate system to obtain three blades 3 with the same distance from the fixed point on the blade 3 to the top of the stator outer ring 1 as alignment blades. Y is the theoretical value of the distance from the fixed point to the top of the stator outer ring 1.

[0057] S3: Using the three alignment blades as reference surfaces, place shims of different thicknesses under the B surface of the stator outer ring 1;

[0058] S4: Turning the A surface of the stator outer ring 1;

[0059] S5: Turn over the stator assembly and turn the B surface of the stator outer ring 1;

[0060] S6: Flip the stator assembly again, press the stator assembly onto the machining platform, adjust the feed rate and turn the A surface again, and finally control the height between the fixed point on the blade 3 and the A surface to be within the qualified range.

[0061] The difference between this embodiment and embodiment 1 is that:

[0062] The three aligning blades constitute a reference surface. To avoid errors in obtaining the reference surface due to the three aligning blades being too close together, it is necessary to find alternate blades 3 as aligning blades. Specifically, the number of alternate blades 3 between the three blades 3 should be greater than eight. Specifically, use a marker to mark the corresponding aligning blades.

[0063] Before machining, surface B of the stator outer ring 1 is uneven. Therefore, in step 3, shims of varying thickness are placed according to the gaps between surface B and the machining table. This ensures a tight fit between surface B and the machining table, preventing the stator assembly from shaking while surface A is being machined.

[0064] After turning, the flatness of the B surface of the stator outer ring 1 is tested and the flatness is controlled within 0.04mm. This ensures the stability of the B surface when it is again bonded to the processing table.

[0065] The flatness of surface A after turning again is controlled within 0.05mm.

[0066] Before turning surface A again, it is necessary to first find the maximum and minimum values ​​of the blade height after the first turning of surface A, calculate the average of the maximum and minimum values, and then subtract Y to obtain the feed amount for the second turning of surface A.

[0067] Example 3

[0068] like Figures 4-5 As shown, the difference between this embodiment and embodiment 1 is that:

[0069] The first turning allowance for side A is 0.5 mm, and then the actual dimension between the blade 3 and side A at this time is calculated. The stator sub-assembly is flipped 180° and fixed. Then the actual machining height for this process is H2 = H3 + F. The calculation method for H2 is as follows: The theoretical height of the stator sub-assembly for this process is H3 = H4 + 0.5 mm, where H4 is the final height dimension, the variable of the theoretical height is F, and the parameter F is calculated according to the following method: F = {[(maximum value of (Y + 0.5) + minimum value of (Y + 0.5)) / 2 - theoretical blade height (Y + 0.5)}. After the calculation, this process is machined according to the total height H2 = H3 + F. The pressure plate is loosened, and the stator sub-assembly is removed from the machine tool. The stator sub-assembly is flipped 180° again, with the side surface of the stator outer ring 1 as the reference surface, and the stator sub-assembly is fixed. The end face of the mounting edge A is machined again by turning according to the theoretical height H4 (actual height of the outer ring). The total height H4 of the stator sub-assembly is ensured, and Y ± 0.25 is also ensured at this time.

[0070] If the height of the blade 3 is ensured and there are subsequent processes for machining the total height of the stator sub-assembly, the height of the blade 3 will be affected during the process of machining the total height of the stator sub-assembly. The process tolerances for the height of the blade 3 and the subsequent process for machining the total height of the stator sub-assembly should be tightened. Assume that the original tolerance of the blade 3 is P, and the tightened tolerance is G. Then the reserved tolerance M pre of the blade 3 = P - G. The sum of the process tolerances X total for machining the total height should be less than the reserved tolerance M of the blade, that is, X total < M pre.

[0071] Obviously, the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A method for machining the blade size in a low-pressure stator assembly, characterized in that: The specific steps include: S1: Add layers to be turned at the upper and lower ends of the stator outer ring, and then weld the low-pressure stator outer ring, low-pressure stator inner ring and blades; S2: Place the welded low-pressure stator assembly on a horizontal platform, and establish a coordinate system to obtain three blades with the same distance from the fixed point on the blade to the top of the stator outer ring as alignment blades; S3: Using the three alignment blades as reference planes, place shims of different thicknesses under the B surface of the stator outer ring; S4: Turning the A surface of the stator outer ring; S5: Turn over the stator assembly and turn the B surface of the stator outer ring; S6: Flip the stator assembly again, press the stator assembly on the processing platform, adjust the feed amount and turn the A surface again, and finally control the height between the fixed point on the blade and the A surface to be within the qualified range.

2. A method for machining blade size in a low-pressure stator assembly according to claim 1, characterized in that: In step S2, the number of interval blades between the three alignment blades is greater than eight.

3. The method for machining the blade size of a low-pressure stator assembly according to claim 1, characterized in that: In step S3, spacers of different thicknesses are placed according to the flatness of the B surface of the stator outer ring, thereby ensuring that the corresponding fixing points on the three alignment blades are in the same horizontal plane.

4. The method for machining the blade size of a low-pressure stator assembly according to claim 1, characterized in that: The step S4 also includes testing the flatness of the B surface of the stator outer ring after turning, and the flatness is controlled within 0.04 mm.

5. The method for machining the blade size of a low-pressure stator assembly according to claim 1, characterized in that: In step S6, the flatness of surface A after further turning is controlled within 0.05 mm.

6. The method for machining the blade size of a low-pressure stator assembly according to claim 1, characterized in that: In step S6, the feed amount is calculated by finding the maximum and minimum values ​​of the blade height of the first turning end face.

7. A method for machining blade size in a low-pressure stator assembly according to claim 6, characterized in that: The feed amount C=the average value of the maximum value and the minimum value minus Y.

8. The method for machining the blade size of a low-pressure stator assembly according to claim 1, characterized in that: The fixed point is the intersection of a circle with a radius of 160 mm and the blade, with the center of the stator assembly as the center.

9. The method for machining the blade size of a low-pressure stator assembly according to claim 1, characterized in that: In step S2, a marking pen is used to mark the alignment blade.

10. The method for machining blade size in a low-pressure stator assembly according to claim 1, characterized in that: In step S5, the B surface is parallel to the A surface after turning.

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