Chamfer Modeling Method and Machining Method of Compressor Blades

Abstract

The present invention discloses a chamfering modeling method and a machining method for a compressor blade. The chamfering modeling method comprises the following steps: inputting a basic model of a compressor blade without chamfers and including a shroud; determining a plurality of chamfer arcs in the chamfer region on the basic model; respectively selecting a plurality of points on each chamfer arc according to the same rule, connecting the points at corresponding positions on the plurality of chamfer arcs to form a closed curve, and obtaining the blade profile curve of the chamfer region; replacing the profile curve of the blade profile section of the compressor blade at the corresponding position in the basic model with the obtained blade profile curve of the chamfer region to obtain a blade model with chamfers. By adopting the above method to perform chamfering modeling on the design model of the compressor blade, the present invention effectively guarantees the integrity of the blade profile curve in the chamfer region of the design model of the compressor blade, avoids the "breakage" situation that occurs when directly chamfering by using CAD / CAM software, and thus facilitates subsequent strength calculation and production manufacturing by using this design model.

Description

Technical Field

[0001] The present invention relates to a chamfering modeling method and a machining method for compressor blades. Background Art

[0002] In the compressor components of aeroengines, gas turbines, and ground axial compressors, rotor blades and stator blades are common components. Chamfering the compressor blades at their blade roots and tips is a very important task for both design and manufacturing. Before manufacturing the compressor blades, strength calculations are carried out to avoid the compressor blades not meeting the service strength. The strength calculations of the compressor blades are generally carried out in relevant software, which requires a complete design model of the compressor blades. The complete design model of the compressor blades is generally obtained by first drawing a basic model and then chamfering the blade roots and tips of the basic model of the compressor blades through CAD / CAM (Computer Aided Design and Computer Aided Manufacturing) software. Chamfering the basic model of the compressor blades by CAD / CAM may result in a "breakage" phenomenon, which will cause problems for subsequent blade strength calculations and also affect the machining effect during subsequent manufacturing. Summary of the Invention

[0003] The technical problem to be solved by the present invention is the defect that chamfering the basic model of the compressor blades by CAD / CAM in the prior art may result in "breakage", affecting subsequent blade strength calculations and manufacturing, and provides a chamfering modeling method and a machining method for compressor blades.

[0004] The present invention solves the above technical problems through the following technical solutions:

[0005] The present invention provides a chamfering modeling method for a compressor blade. A rim platform of the compressor blade is integrally formed at the blade root and / or tip of the compressor blade. A chamfer with a radius of R is provided at the connection between the compressor blade and the rim platform. The chamfering modeling method includes the following steps:

[0006] S1. Input the basic model of the compressor blade without chamfering and including the rim platform;

[0007] S2. Determine one of the chamfer arcs in the chamfering area on the basic model:

[0008] Select a point X on the blade profile at the blade root and / or tip of the compressor blade. Select a point P on the rim platform in the normal direction of point X. Find the normal vector of point P and obtain the center O of the sphere S1 according to the chamfer radius R. Calculate the minimum value l of the distance from the coordinate points on the blade profile of the compressor blade to the center O of the sphere min ;

[0009] By moving point P in the normal direction at point X, points A and B are respectively found such that at point A, l min >R, and at point B, l min <R. Then, by using the bisection method, the sphere S1 is made tangent to the blade profile surface of the compressor blade. The tangent point C between the sphere S1 and the rim surface and the tangent point D between the sphere S1 and the blade surface of the compressor blade are calculated. The circular arc with the center at point O and radius R passing through the tangent point C and the tangent point D is the chamfering circular arc;

[0010] S3. Repeat step S2 to determine multiple chamfering circular arcs in the circumferential direction of the compressor blade;

[0011] S4. At each chamfering circular arc, multiple points are respectively selected according to the same rule, and the points at corresponding positions on the multiple chamfering circular arcs are connected to form a closed curve, obtaining the profile line of the blade profile cross-section of the chamfering area;

[0012] S5. Replace the blade profile line at the corresponding position in the basic model with the obtained blade profile line of the chamfering area to obtain a blade model with chamfers.

[0013] In this solution, by adopting the above method, the integrity of the blade profile line in the chamfering area of the designed model of the compressor blade after chamfering can be effectively guaranteed, avoiding the "breakage" situation that occurs when directly chamfering using CAD / CAM software, thereby facilitating subsequent strength calculation and production manufacturing using this designed model.

[0014] Preferably, in step S2, the tangent point D is obtained through the following steps:

[0015] S21. On the compressor blade, find point D1 such that the absolute value of the difference between the distance from this point D1 to the center of the sphere O and the chamfering radius R is the smallest;

[0016] S22. Select points D2 and D3 on the circumference of the blade profile where point D1 is located and on both sides of point D1, determine the sphere S2 passing through these four points D1, D2, D3, and point X, and determine the center of the sphere O1 of the sphere S2;

[0017] S23. Connect the center of the sphere O of the sphere S1 and the center of the sphere O1 of the sphere S2 into a straight line. The tangent point D is located between the center of the sphere O and the center of the sphere O1 and the distance from it to the center of the sphere O is R.

[0018] In this solution, the boundary of the chamfering circular arc on the blade profile surface of the compressor blade can be quickly obtained through the above method.

[0019] Preferably, when selecting points D2 and D3, they should be located on the same blade profile of the compressor blade.

[0020] In this solution, points D2 and D3 are selected on the same side of the compressor blade to obtain more accurate results.

[0021] Preferably, in step S4, the airfoil profile of the obtained chamfered area is smoothed.

[0022] In this solution, smoothing treatment is adopted to make the chamfering effect better.

[0023] Preferably, step S5 further includes the following steps:

[0024] S51. Determine the upper airfoil and the lower airfoil in the basic model of the compressor blade that are the same as the airfoil at the upper boundary and the lower boundary of the chamfered arc respectively;

[0025] S52. Corresponding replace all the airfoil profiles between the upper airfoil and the lower airfoil in the basic model of the compressor blade with the airfoil profile of the chamfered area obtained in step S4, and then the blade model with chamfers is obtained.

[0026] Preferably, after step S5, the following steps are further included:

[0027] S6. Generate the blade profile coordinate points of the blade model with chamfers and output them.

[0028] In this solution, generating the blade profile coordinate points of the blade model with chamfers can be input into a numerical control machine tool for machining the compressor blade.

[0029] The present invention also provides a machining method for a compressor blade. The machining method includes chamfering the blade root and / or the blade tip of the compressor blade by using the above-mentioned chamfering modeling method for the compressor blade.

[0030] Preferably, the machining method further includes the following steps:

[0031] Generate the blade profile coordinate points of the blade model with chamfers;

[0032] Input the blade profile coordinate points into a numerical control machine tool, start the numerical control machine tool for machining, and obtain the compressor blade.

[0033] The positive and progressive effects of the present invention are as follows: By chamfering and modeling the design model of the compressor blade by using the above method, the integrity of the airfoil profile of the chamfered area of the design model of the compressor blade can be effectively guaranteed, and the situation of "damage" caused by directly chamfering with CAD / CAM software can be avoided, so as to facilitate subsequent strength calculation and production and manufacturing by using this design model. Description of the Drawings

[0034] Figure 1Schematic flow chart of the chamfering method for compressor blades in a preferred embodiment of the present invention.

[0035] Figure 2 Schematic diagram of the chamfering of compressor blades in a preferred embodiment of the present invention.

[0036] Figure 3 Schematic diagram of the blade profile curve at the root of the compressor blade located on the platform in a preferred embodiment of the present invention.

[0037] Figure 4 Schematic diagram for solving the tangent point position of the spherical ball S1 and the platform in a preferred embodiment of the present invention.

[0038] Figure 5 Schematic diagram for solving the tangent point position of the spherical ball S1 and the surface of the compressor blade in a preferred embodiment of the present invention.

[0039] Explanation of reference numerals:

[0040] Compressor blade 100

[0041] Blade surface 101

[0042] Platform 200

[0043] Platform surface 201

[0044] Chamfering area 300 Detailed implementation manners

[0045] The present invention will be more clearly and completely described below by way of embodiments in conjunction with the accompanying drawings, but the present invention is not limited thereto within the scope of these embodiments.

[0046] An axial flow compressor refers to a multi-stage compression device in which the air flow direction is the same as or nearly the same as the axis direction of the working wheel rotation, and is composed of a tip flow channel and a series of stator-rotor blades arranged alternately, and is commonly used in aeroengines or gas turbines; the combination of adjacent stator and rotor blades is called a stage. Both the stator blades and the rotor blades are called compressor blades. As Figure 2 shown, for the convenience of installation of the compressor blade 100, the platform 200 of the compressor blade 100 is integrally formed at the root and / or tip of the compressor blade 100. There is generally a chamfer at the connection between the compressor blade 100 and the platform 200. Due to the usage scenario of the compressor blade 100, it is necessary to ensure the machining accuracy of the compressor blade 100. Generally, automated machining equipment is used for production, which requires ensuring the integrity of the design model lines of the compressor blade 100 to avoid the missing of coordinate points of the blade profile curve derived from this design model, which affects the machining.

[0047] As Figures 1 - 5As shown, this embodiment discloses a chamfering modeling method for a compressor blade 100. By adopting this chamfering modeling method, the integrity of the blade profile line of the design model of the compressor blade 100 in the chamfering area 300 can be effectively ensured, and the situation of "breakage" caused by directly chamfering the design model of the blade using CAD / CAM software can be avoided, thus facilitating subsequent strength calculation and production manufacturing using this design model. As Figure 1 shown, the chamfering modeling method for the compressor blade 100 includes the following steps:

[0048] S1. Input the basic model of the compressor blade 100 without chamfers including the rim 200. The basic model of the compressor blade 100 can be obtained through an aerodynamic design method.

[0049] S2. Determine one of the chamfering arcs in the chamfering area 300 of the basic model. The specific steps are as follows:

[0050] As Figure 3 shown, assume that the chamfering radius of the chamfering area 300 is R. Select a point X on the blade profile of the compressor blade 100 at the blade root and / or blade tip. Select a point P on the rim 200 in the normal direction of point X. Find the normal vector of point P and obtain the center O of the sphere S1 according to the chamfering radius R. Calculate the minimum value l of the distance from the coordinate point of the blade profile of the compressor blade 100 to the center O of the sphere min .

[0051] Then, as Figure 4 shown, by moving point P in the normal direction of point X, find points A and B respectively, such that l min >R at point A and l min <R at point B. Then, obtain the arc that makes the sphere S1 tangent to the blade surface of the compressor blade 100 through the bisection method. Calculate the tangent point C of the sphere S1 and the rim surface 201 and the tangent point D of the sphere S1 and the blade surface 101 of the compressor blade 100. The arc passing through the tangent points C and D with the center at point O and radius R is the chamfering arc.

[0052] S3. Repeat the above step S2 to determine multiple chamfering arcs in the circumferential direction of the compressor blade 100. In this step, determine as many chamfering arcs as possible in the circumferential direction of the compressor blade 100 to make the blade profile of the chamfering area 300 smoother. In the above chamfering modeling steps, the chamfering modeling can be first performed on the pressure side of the blade of the compressor blade 100, and then the same method can be used for the suction side of the blade of the compressor blade 100 and the leading and trailing edge areas. Of course, it is also possible to first perform chamfering modeling on the suction side of the blade of the compressor blade 100 or the leading and trailing edge areas. No specific limitation is made here.

[0053] S4. Select multiple points on each chamfer arc respectively according to the same rule, connect the points at corresponding positions on the multiple chamfer arcs to form a closed curve, and obtain the blade profile line of the chamfer region 300.

[0054] In this step, it is assumed that N points (including the end points at both ends of the chamfer arc) are evenly selected corresponding to each chamfer arc. Connect the points at corresponding positions on each chamfer arc in the circumferential direction to form a closed curve, and N blade profile lines of the chamfer region 300 can be obtained. Among them, the upper boundary and the lower boundary of the blade profile line of the chamfer region 300 are the closed curves formed by the end points at both ends of the chamfer arc respectively.

[0055] The blade profile at the upper boundary of the blade profile line of the chamfer region 300 is the plane within the closed curve formed by all the tangent points of the spherical ball S1 and the blade surface 101. The blade profile at the lower boundary of the blade profile line of the chamfer region 300 is the plane within the closed curve formed by all the tangent points of the spherical ball S1 and the flange surface 201.

[0056] The blade profile between the upper boundary and the lower boundary within the chamfer region 300 is the plane within the closed curve formed by the N - 2 points with the same label on the blade profile line of the chamfer region 300 after removing the end points at both ends of the chamfer arc.

[0057] S5. Replace the blade profile line of the compressor blade 100 at the corresponding position in the base model with the obtained blade profile line of the chamfer region 300 to obtain a blade model with chamfers.

[0058] Specifically, please refer to Figure 5 As shown, in this embodiment, the tangent point D in step S2 is obtained through the following steps:

[0059] S21. Find a point D1 on the compressor blade 100 such that the absolute value of the difference between the distance from this point D1 to the center of the sphere O and the chamfer radius R is the smallest.

[0060] S22. Select points D2 and D3 on both sides of point D1 in the circumferential direction of the blade profile line where point D1 is located, determine the spherical ball S2 passing through the four points D1, D2, D3, and point X, and determine the center of the sphere O1 of the spherical ball S2.

[0061] S23. Connect the center of the sphere O of the spherical ball S1 and the center of the sphere O1 of the spherical ball S2 into a straight line. The tangent point D is located between the center of the sphere O and the center of the sphere O1 and the distance from it to the center of the sphere O is R.

[0062] Through the above method, the boundary of the chamfer arc on the blade profile surface of the compressor blade 100 can be obtained quickly.

[0063] Moreover, when selecting points D2 and D3, they should be located on the same blade profile of the compressor blade 100. Selecting points D2 and D3 on the same blade profile of the compressor blade 100 makes the obtained results more accurate.

[0064] In step S4 of the present embodiment, fairing is performed on the blade profile of the obtained chamfered region 300. Performing fairing makes the chamfering effect better.

[0065] Of course, in other embodiments, fairing may not be performed. Specifically, it can be determined by the designer according to the specific situation after chamfering the design model.

[0066] In the present embodiment, step S5 further includes the following steps:

[0067] S51. Determine the upper blade profile and the lower blade profile that are the same as the blade profile at the upper boundary and the lower boundary of the chamfered arc respectively in the basic model of the compressor blade 100.

[0068] S52. Correspondingly replace all the blade profiles between the upper blade profile and the lower blade profile in the basic model of the compressor blade 100 with the blade profile of the chamfered region 300 obtained in step S4, and then the blade model with chamfers is obtained.

[0069] Preferably, after step S5, the following steps are further included:

[0070] S6. Generate and output the blade profile coordinate points of the blade model with chamfers. Generating the blade profile coordinate points of the blade model with chamfers can be input into a numerical control machine tool for machining the compressor blade 100.

[0071] The present invention also provides a machining method for a compressor blade 100. The machining method includes chamfering the blade root and / or the blade tip of the compressor blade 100 by using the chamfering modeling method for the compressor blade 100 as described above.

[0072] Specifically, the machining method for the compressor blade 100 further includes the following steps:

[0073] Generate the blade profile coordinate points of the blade model with chamfers;

[0074] Input the blade profile coordinate points into a numerical control machine tool, start the numerical control machine tool for machining, and obtain the compressor blade 100.

[0075] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that this is only for illustration. The protection scope of the present invention is defined by the appended claims. Without departing from the principles and essence of the present invention, those skilled in the art can make various changes or modifications to these embodiments, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A chamfering method for a compressor blade, characterized in that At the root and / or tip of the compressor blade, a shroud of the compressor blade is integrally formed. At the connection between the compressor blade and the shroud, there is a chamfer with a radius of R. The chamfer shaping method includes the following steps: S1. Input the basic model of the compressor blade without chamfer including the shroud; S2. Determine one of the chamfer arcs in the chamfer area on the basic model: Select a point X on the blade profile at the root and / or tip of the compressor blade. Select a point P on the shroud in the normal direction of point X. Find the normal vector of point P and obtain the center O of the sphere S1 according to the chamfer radius R. Calculate the minimum value lmin of the distance from the coordinate points on the blade profile of the compressor blade to the center O of the sphere; By moving point P in the normal direction of point X, find points A and B respectively, such that lmin > R at point A and lmin < R at point B. Then, use the bisection method to obtain that the sphere S1 is tangent to the blade surface of the compressor blade. Calculate the tangent point C between the sphere S1 and the shroud surface and the tangent point D between the sphere S1 and the blade surface of the compressor blade. The arc with the center at point O and a radius of R passing through the tangent point C and the tangent point D is the chamfer arc. Among them, the tangent point D is obtained through the following steps: S21. Find a point D1 on the compressor blade such that the absolute value of the difference between the distance from this point D1 to the center O of the sphere and the chamfer radius R is the smallest; S22. Select points D2 and D3 on the circumference of the blade profile where point D1 is located on both sides of point D1. Determine the sphere S2 passing through the four points D1, D2, D3, and point X, and determine the center O1 of the sphere S2; S23. Connect the center O of the sphere S1 and the center O1 of the sphere S2 into a straight line. The tangent point D is located between the center O of the sphere and the center O1 of the sphere and the distance to the center O of the sphere is R; S3. Repeat step S2 to determine multiple chamfer arcs in the circumferential direction of the compressor blade; S4. Select multiple points on each chamfer arc according to the same rule respectively, and connect the points at the corresponding positions on the multiple chamfer arcs to form a closed curve to obtain the blade profile of the chamfer area; S5. Replace the blade profile at the corresponding position in the basic model with the blade profile of the chamfer area obtained to get the blade model with chamfer; 2. The chamfering method of the compressor blade according to claim 1, characterized in that Points D2 and D3 should be selected on the same blade profile of the compressor blade.

3. The chamfering modeling method of the compressor blade according to claim 1, characterized in that, In step S4, smooth the blade profile of the obtained chamfer area.

4. The chamfering method of the compressor blade according to claim 1, wherein Step S5 further includes the following steps: S51. Determine the upper blade profile and the lower blade profile in the basic model of the compressor blade that are the same as the blade profile at the upper boundary and the lower boundary of the chamfer arc respectively; S52. Replace all the blade profiles between the upper blade profile and the lower blade profile in the basic model of the compressor blade with the blade profile of the chamfer area obtained in step S4 to obtain the blade model with chamfer.

5. The chamfering method of the compressor blade according to claim 1, characterized in that, After step S5, the following steps are further included: S6. Generate the blade profile coordinate points of the blade model with chamfer and output them.

6. A processing method for a compressor blade, characterized in that, The machining method includes chamfering the blade root and / or blade tip of the compressor blade by using the chamfering modeling method of the compressor blade as described in any one of claims 1-4.

7. The processing method of the compressor blade according to claim 6, wherein, The machining method further includes the following steps: Generating blade profile coordinate points from the blade model with chamfers; Inputting the blade profile coordinate points into a numerical control machine tool, starting the numerical control machine tool for machining, and obtaining the compressor blade.

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