Compressor blade grinding machining model optimization method

Abstract

The invention discloses a compressor blade grinding model optimization method, which is characterized in that after a compressor blade theoretical model is split according to regions, compared with an integral theoretical model, the compressor blade theoretical model is more beneficial to programming and optimization of machining programs of each region according to numerical control grinding steps. A compressor blade theoretical model has the phenomena of local curvature radius sudden change, distortion, intersection and folding of molded surfaces at corners and the like, so that a cutter projection cannot be attached; each curved surface part of the optimized and reconstructed model is in smooth transition, and the tool path is uniform and smooth. The reference cutter shaft vector is given, cutter shaft control can be conveniently carried out during numerical control grinding machining programming, cutter shaft swing in program control is more consistent, the connecting positions of all machining programs are smoother, and the consistency of numerical control grinding machining surfaces is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing, and in particular relates to a compressor blade grinding processing model optimization method. Background Art

[0002] Blades are one of the key components of aircraft engines. They work in high temperature, high pressure, and high speed environments for a long time, and they also have to withstand great centrifugal force and airflow scouring. With the continuous improvement of the performance and power of aircraft engines, the quality requirements of blades are extremely stringent. At present, the precision machining method of the blade body of aircraft engine blades is mainly precision milling.

[0003] In recent years, with the widespread application of advanced technologies such as super-hard abrasives, CNC grinding, and high-speed grinding, high-speed grinding has become increasingly popular in the precision machining industry. Grinding has the advantages of high precision, high efficiency, stable process, and integrated rough and fine processing. However, the current grinding in the industry is mostly aimed at internal and external cylindrical grinding and surface grinding. For small-sized compressor blades with higher processing requirements and greater difficulty, due to the structural characteristics of CNC grinding tools that are different from CNC milling cutters, the optimization of the processing model and the control of the tool axis are required to be higher when performing compressor blade grinding. The current proficiency of CNC grinding technology for aircraft engine compressor blades is not high.

[0004] The Chinese invention patent with publication number CN110900379B discloses a method for robot belt grinding and polishing of compressor blades, which optimizes and adjusts the main influencing factors when cutting in and out, and estimates multiple sets of optimization parameters. The method of the present invention minimizes over-grinding and under-grinding, and improves the surface quality and flatness of the workpiece. This solution is mainly improved from the perspective of intelligent coordination of cutting in and out, aiming to improve the surface contour accuracy and dimensional accuracy of the blades. However, it is necessary to build a robot grinding and polishing platform, and to lay out the robot, grinding and polishing machine, and detection device, and the initial investment cost is too high. Summary of the invention

[0005] In order to solve the above problems, the present invention aims to provide a method for optimizing a compressor blade grinding processing model.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme: a compressor blade grinding model optimization method, comprising the following steps:

[0007] Step 1: Establishment of theoretical model: Establish theoretical 3D model of compressor blade by UG 3D model design software, and construct a reference knife axis vector group for selection, where the model includes complete blade body, tenon, edge plate and transition arcs of various parts;

[0008] Step 2: Model splitting: split the theoretical model according to the machining parts and order of CNC grinding, and split the blade into the leading edge, trailing edge, basin-facing blade body, back-facing blade body, basin-facing edge plate, back-facing edge plate and blade root transition arc;

[0009] Step 3: Model optimization, using UG three-dimensional model design software to optimize and reconstruct each part of the blade theoretical model;

[0010] Step 4: Tool axis optimization. According to the surface features of each part of the blade, select a group of reference tool axis vectors constructed in step 1. According to the processing characteristics of each part, refine the tool axis control through Cartesian coordinate system or spherical coordinate system.

[0011] Furthermore, the edge plates in step 1 are divided into horizontal plane edge plates, inclined plane edge plates and curved surface edge plates. According to the different requirements of grinding processing for different types of edge plates, reference tool axis vector groups for selection are constructed respectively.

[0012] Furthermore, the reference knife axis vector of the horizontal plane edge plate component is as follows: draw a straight line from the zero point of the blade coordinate system to coincide with the Zc axis, and rotate the straight line with the zero point as the axis point, and the Xc and Yc axes as the rotation axes, respectively, at an interval of 2° for multiple times to obtain two sets of reference knife axis vectors in the directions perpendicular and parallel to the blade body;

[0013] The reference tool axis vectors of inclined plane edge plates and curved edge plate components are as follows: construct 3 sets of isoparametric curves in the U direction and V direction on the edge plate surface, use the intersection of the isoparametric curves to find the geometric center point of the plane or curved surface, and construct a straight line with the geometric center point as the starting point, with the direction being the normal of the edge plate surface, and the starting point of the straight line as the axis point. The U-direction / V-direction isoparametric curve at the geometric center point or the tangent of the U-direction / V-direction isoparametric curve and the edge plate surface is used as the rotation axis. Rotate multiple times at an interval of 2° to obtain a set of reference tool axis vectors perpendicular to / parallel to the blade body direction.

[0014] Furthermore, the model splitting in step 2 divides the seven parts of the blade into four groups for optimization, namely the leading and trailing edges of the blade, the back edge plate of the blade basin, the back edge plate of the blade basin, and the blade root transition arc. Then, the four groups of models are split out from the wheel model, and the segmentation points are selected for splitting.

[0015] Furthermore, the division points of the leading and trailing edges of the blade and the blade basin facing away from the blade body are selected at the tangent points of the blade body curved surface and the leading and trailing edges, and are split along the Zc axis direction. The leading and trailing edge models split from the leading and trailing edges of the blade are similar in width in the Xc axis direction, and the basin and back models split from the blade basin facing away from the blade body have large curvature at the edges and remain vertical along the Zc axis direction; the splitting boundary of the blade basin facing away from the edge plate is the plane or arc surface area outside the root transition arc; the splitting point of the blade root transition arc should be the point where the arc is tangent to the blade body profile and the edge plate surface.

[0016] Furthermore, the model optimization in step 3 includes the following steps:

[0017] Step 31: Extracting curves, extracting edge curves of each group;

[0018] Step 32: Surface smoothing: smoothing the curve using curve parameters;

[0019] Step 33: Surface reorganization: construct a new surface from the smoothed curves and compare it with the original theoretical model to see if it is distorted. If the conditions are not met, repeat steps 31 and 32 until the requirements are met.

[0020] Furthermore, the curved surface in the model optimization step of the blade basin back edge plate is smoothly replaced by

[0021] Offset curve: Use the curve extracted in step 31 of the offset curve command on the surface. The support surface is the edge of the theoretical model, and the offset size exceeds the edge of the edge of the theoretical model.

[0022] Curve reorganization: The extracted curve in step 31 and the offset curve are combined into a fan-shaped surface, and the size of the surface can completely cover the edge plate surface of the theoretical model.

[0023] Furthermore, the processing steps for the leading and trailing edges of the blade in step 4 are specifically as follows: control the swing angle of the tool axis, select a vector with a suitable inclination angle from the reference vector group constructed parallel / perpendicular to the blade body direction as the tool axis direction, and the tool axis is tilted from the leading and trailing edges to the blade body direction. When the reference tool axis vector cannot meet the requirements, the vector can be fine-tuned with the aid of a Cartesian coordinate system or a spherical coordinate system.

[0024] Furthermore, the processing steps of the basin back edge plate and the basin back blade body in step 4 are specifically as follows: a vector is selected, and the tool axis has a certain inclination angle relative to the edge plate surface. The inclination direction should be: when the basin is processed toward the blade body, it is inclined toward the back direction, and when the back blade body is processed, it is inclined toward the basin edge plate. When the reference tool axis vector cannot meet the requirements, the vector can be fine-tuned with the aid of the Cartesian coordinate system or the spherical coordinate system;

[0025] When grinding the entire blade surface including the leading and trailing edges at the same time, a vector is selected and then controlled by the inclination angle of the tool axis vector so that the tool axis can maintain a inclination angle relative to the edge plate surface at each position of the spiral tool path.

[0026] Furthermore, when grinding the blade root transition arc, a vector is selected and controlled by the inclination angle of the tool axis vector, so that the tool axis can maintain a inclination angle relative to the edge plate surface at each position of the spiral tool path.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) After the compressor blade theoretical model is split into regions, it is more conducive to compiling and optimizing the processing programs for each region according to the steps of CNC grinding processing compared to the overall theoretical model.

[0029] (2) The theoretical model of the compressor blade has some problems such as sudden change in local curvature radius, distortion, and intersection and folding of the profile at the corners, which makes it impossible for the tool projection to attach. After optimization and reconstruction, the surface of each part of the model has smooth transition and the tool path is even and smooth.

[0030] (3) Given a reference tool axis vector, it is convenient to control the tool axis during CNC grinding programming, and the tool axis swing is more consistent during program control, making the connection between each processing program smoother and improving the consistency of the CNC grinding surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 The complete compressor blade theoretical model established by the UG three-dimensional model software in the present invention Figure 1 ;

[0033] Figure 2 The complete compressor blade theoretical model established by the UG three-dimensional model software in the present invention Figure 1 ;

[0034] Figure 3 The complete compressor blade theoretical model established by the UG three-dimensional model software in the present invention Figure 1 ;

[0035] Figure 4 The complete compressor blade theoretical model established by the UG three-dimensional model software in the present invention Figure 1 ;

[0036] Figure 5 is a reference knife axis vector in the vertical blade direction constructed by the horizontal edge plate in the present invention;

[0037] Figure 6 A reference knife axis vector parallel to the blade direction constructed by the horizontal edge plate in the present invention;

[0038] Figure 7 It is a schematic diagram of constructing a straight line with the geometric center point as the starting point and the direction of the straight line as the normal direction of the edge plate surface in the present invention;

[0039] Figure 8 A reference knife axis vector in the vertical blade direction constructed by the inclined plane edge plate and the curved edge plate in the present invention;

[0040] Fig. 9 A reference knife axis vector parallel to the blade direction constructed by the inclined plane edge plate and the curved edge plate in the present invention;

[0041] Fig.10 The wheel model in the present invention schematically shows the blade as a whole. Figure 1 ;

[0042] Fig.11 The wheel model in the present invention schematically shows the blade as a whole. Figure 2 ;

[0043] Fig.12 It is a schematic diagram of the optimization of the leading and trailing edge models of the compressor blades in the present invention;

[0044] Fig.13 For the front and rear edge grinding tool axis control in the present invention Figure 1 ;

[0045] Fig.14 For the front and rear edge grinding tool axis control in the present invention Figure 2 ;

[0046] Fig.15 A schematic diagram of a page for fine-tuning a vector using a Cartesian coordinate system in the present invention;

[0047] Fig.16 It is a schematic diagram of the optimization of the compressor blade basin and the back edge plate model in the present invention;

[0048] Fig.17 The present invention is used to control the blade axis of the compressor blade basin and the back edge plate grinding process. Figure 1 ;

[0049] Fig.18 The present invention is used to control the blade axis of the compressor blade basin and the back edge plate grinding process. Figure 2 ;

[0050] Fig.19 This is a schematic diagram of deriving the original curve of the blade body in the present invention;

[0051] Fig. 20 It is a schematic diagram of the optimization of the compressor blade basin and the back-facing blade body model in the present invention;

[0052] Fig.21 The Cartesian coordinates of the blade basin and the back blade body vector are fine-tuned in the present invention. Figure 1 ;

[0053] Fig. 22 The Cartesian coordinates of the blade basin and the back blade body vector are fine-tuned in the present invention. Figure 1 ;

[0054] Fig.23 A schematic diagram of the simultaneous grinding of the entire blade body surface including the leading and trailing edges in the present invention;

[0055] Fig.24 It is a page schematic diagram for controlling the inclination angle of the machining tool axis vector when optimizing the blade basin and the back-facing blade body tool in the present invention;

[0056] Fig.25 A schematic diagram of the selection and optimization of the circular arc cutter shaft for the blade root transfer of the compressor blade in the present invention;

[0057] In the figure, 1-leading edge; 2-trailing edge; 3-basin-facing blade body; 4-back-facing blade body; 5-basin-facing edge plate; 6-back-facing edge plate; 7-blade root transition arc. DETAILED DESCRIPTION

[0058] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above-mentioned technical ideas of the present invention, various modifications, substitutions and changes made according to the common technical knowledge and customary means in the field are included in the scope of the present invention.

[0059] The invention is only directed to an optimization method for the CNC grinding processing model of aircraft engine compressor blades, as follows.

[0060] Step 1: Establish the theoretical model. Use UG 3D model design software to establish the theoretical 3D model of the compressor blade. The model should include the complete blade body, edge plate and transition arc.

[0061] Step 2: Model splitting. The theoretical model is split according to the processing location and order of CNC grinding. The blade is split into seven parts: leading edge 1 (inlet edge), trailing edge 2 (exhaust edge), basin-facing blade body 3, back-facing blade body 4, basin-facing edge plate 5, back-facing edge plate 6, and blade root transition arc 7.

[0062] Step 3: Model optimization, using UG three-dimensional model design software, optimize and reconstruct the seven parts divided into the blade theoretical model.

[0063] Step 4: Tool axis optimization: According to the surface characteristics of each part of the blade, a set of reference tool axis vectors are constructed for selection. According to the processing characteristics requirements of each part, the tool axis control is refined through the Cartesian coordinate system or the spherical coordinate system.

[0064] Specific implementation cases of the invention:

[0065] Step 1: The theoretical model of the compressor blade is established and a set of optional reference knife axis vector groups are constructed according to the surface characteristics of each part of the blade.

[0066] 1. According to the design drawing requirements, use UG 3D model software to establish a complete compressor blade theoretical model. The model includes the complete blade body, tenon, edge plate and the arc requirements of each part, such as Figure 1-4 shown.

[0067] 2. Compressor blade edge plates are divided into horizontal plane edge plates, inclined plane edge plates and curved surface edge plates. According to the different requirements for grinding of different types of edge plates, the following reference tool axis vector groups are constructed for selection:

[0068] 2.1 Horizontal plane edge plate

[0069] Draw a straight line from the zero point of the blade coordinate system to coincide with the Zc axis. Take the zero point as the axis point and the Xc axis as the rotation axis. Rotate the straight line multiple times at an interval of 2° to obtain a set of reference tool axis vectors perpendicular to the blade body, such as Figure 5 As shown; by rotating the straight line with the zero point as the axis point and the Yc axis as the rotation axis for multiple times at an interval of 2°, a set of reference tool axis vectors parallel to the blade direction can be obtained, as shown in Figure 6 shown.

[0070] 2.2 Inclined plane edge plate and curved edge plate

[0071] Construct three sets of isoparametric curves in the U direction and V direction in the edge plate surface, and use the intersection of the isoparametric curves to find the geometric center point of the plane or surface. Take the geometric center point as the starting point and construct a straight line with the direction as the normal direction of the edge plate surface, such as Figure 7 As shown. Taking the starting point of the straight line as the axis point, the U-direction isoparametric curve at the geometric center point or the tangent of the U-direction isoparametric curve and the edge plate surface as the rotation axis, a set of reference tool axis vectors perpendicular to the blade direction can be obtained by rotating multiple times at an interval of 2°, as shown in Figure 8 As shown; take the starting point of the straight line as the axis point, the V-direction isoparametric curve at the geometric center point or the tangent of the V-direction isoparametric curve and the edge plate surface as the rotation axis, and rotate multiple times at an interval of 2° to obtain a set of reference tool axis vectors parallel to the blade direction, as shown in Fig. 9shown.

[0072] Step 2: Split, reorganize and optimize the compressor blades according to their processing areas and parts. Fig.10 and 11 As shown, the blade is divided into a leading edge 1, a trailing edge 2, a basin-to-blade body 3, a back-to-blade body 4, a basin-to-edge plate 5, a back-to-edge plate 6 and a blade root transition arc 7. The seven parts of the blade are divided into four groups for optimization, namely, the leading and trailing edges of the blade, the back-to-edge plate of the blade basin, the back-to-blade body of the blade basin, and the blade root transition arc.

[0073] 1. Optimization of leading and trailing edges of compressor blades

[0074] 1.1 Compressor blade leading and trailing edge model splitting

[0075] like Fig.10 and Fig.11 As shown in the figure, the leading and trailing edges of the blade are separated from the blade body model from the wheel model. The splitting point should be selected at the tangent point between the blade body surface and the leading and trailing edges, and the splitting should be performed along the Zc axis direction, so that the width of the split leading and trailing edge models in the Xc axis direction is similar.

[0076] 1.2 Compressor blade leading and trailing edge model optimization

[0077] ① Extract curves: extract the edge curves of the front and rear edge profiles and check their integrity. ② Curve smoothing: smooth the curves through curve parameters. The number of curve approximation points should be adjusted according to the length of the curve and the size of the local curvature radius. The number of points should not be too small to cause curve distortion. ③ Surface reconstruction: use the curve mesh command to smooth the front and rear edge curves to form a new surface. Analyze whether the curvature transition of the newly generated surface is smooth and whether it is distorted compared with the original theoretical model. If the conditions are not met, repeat the above ② and ③ steps until the requirements are met. Fig.12 shown.

[0078] 1.3 Selection and optimization of tool axis for compressor blade leading and trailing edge machining

[0079] In the grinding process, the front and rear edges need to be processed separately, and the trimming quickly removes the excess. In order to ensure the processing effect and the local interference that is easy to cause during processing, it is necessary to control the swing angle of the tool axis of the machine tool. Fig.13 and Fig.14As shown, a vector with a suitable inclination angle is selected from the reference vector group parallel to the blade direction constructed in step 1, point 2 as the tool axis direction. The tool axis should be tilted from the front and rear edges to the blade direction to ensure that the grinding tool has a certain inclination angle relative to the Xc-Yc plane or the edge plate surface, and will not interfere with the blade fixture during the processing; at the same time, the tool bar swing angle should not be too large, resulting in interference between the tool bar and the tip of the blade. The angle control in this step should be selected considering the shape and size of the blade and the size of the grinding tool and tool bar. When the reference tool axis vector cannot meet the requirements, the vector can be fine-tuned with the help of the Cartesian coordinate system, such as Fig.15 shown.

[0080] 2. Compressor blade basin and back edge plate optimization

[0081] 2.1 Compressor blade basin and back edge plate model splitting

[0082] like Fig.10 and 11 As shown in the figure, the blade basin and back edge plate are separated from the wheel model. The separation boundary should be the plane or arc surface area outside the root transition arc.

[0083] 2.2 Compressor blade basin and back edge plate model optimization

[0084] ① Extract curve: Extract the curve on the side of the edge plate close to the blade body, that is, the tangent line at the transition arc between the edge plate and the blade root. ② Offset curve: Use the offset curve command on the surface to offset the curve extracted in ①. The support surface is the edge plate surface of the theoretical model. The offset size should exceed the edge of the edge plate surface of the theoretical model. ③ Surface reorganization: Use the "through curve group" command to combine the curve extracted in ① and the offset curve in ② into a fan-shaped surface. The surface size should be able to completely cover the edge plate surface of the theoretical model, such as Fig.16 shown.

[0085] 2.3 Selection and optimization of blade basin and back edge plate cutter shaft for compressor

[0086] When grinding the blade edge, the bottom edge of the grinding tool is used for processing. It is necessary to consider the local interference of the cutting tool on the unprocessed or non-processed area and the interference of the tool shaft on the blade body. Therefore, it is necessary to control the tool shaft swing angle. Fig.17 and Fig.18As shown, select a suitable vector as the tool axis direction from the vector group perpendicular to the blade direction constructed in step one as needed. If the edge plate surface is a horizontal plane, select the vector according to "Step 1 2.1"; if the edge plate surface is an inclined plane or a curved edge plate, select the vector according to "Step 1 2.2". The tool axis should have a certain inclination angle relative to the edge plate surface, and the inclination direction should be: inclined toward the back when processing the basin-toward edge plate, and inclined toward the basin-toward edge when processing the back-toward edge plate. The angle control in this step should be selected based on the shape and size of the blade and the size of the grinding tool and tool rod. When the reference tool axis vector cannot meet the requirements, the Cartesian coordinate system can be used to fine-tune the vector, such as Fig.15 shown.

[0087] 3. Compressor blade basin and back blade optimization

[0088] 3.1 The compressor blade basin and back blade body model should be divided into two parts due to processing requirements.

[0089] (1) Fig.10 and Fig.11 As shown in the figure, the blade basin and back are separated from the blade body model from the wheel model. The split point should be selected where the blade body surface is tangent to the front and rear edges, and the split is performed along the Zc axis. The split basin and back models should have large curvature at the edge and remain vertical along the Zc axis.

[0090] (2) Fig.19 As shown, the original curve of the blade is derived, and the curve should include the blade surface and the leading and trailing edge parts.

[0091] 3.2 Compressor blade basin and back blade model optimization

[0092] (1) ① Extract curves: extract the contour edge curves of the basin and back blade surface. ② Curve smoothing: smooth the curves using curve parameters. When smoothing the curves, do not make major changes to the direction of the curves. ③ Surface reorganization: reorganize the blade surface after blade smoothing using the curve mesh command, and analyze whether the curvature and curvature change of the surface meet the requirements, and whether it is distorted compared to the theoretical blade surface. If they cannot meet the requirements at the same time, repeat steps ② and ③ until the requirements are met. Fig. 20 shown.

[0093] (2) Check the original blade curve for smoothness and perform smoothing. For the partially smooth area, the curve extreme point can be deleted. The smoothed curve "passes through the curve group" to form a new blade profile, and the transition area from the blade to the leading and trailing edges should be tangent and smooth.

[0094] 3.3 Selection and optimization of compressor blade basin and blade shaft facing away from the blade

[0095] (1) When single-sided grinding of the basin and back-facing blades is performed, similar to the processing of the edge plate, it is necessary to consider the local interference of the cutting tool on the unprocessed or non-processed area and the interference of the tool axis on the blade body, so the tool axis swing angle needs to be controlled. If the edge plate surface is a horizontal plane, select the vector according to "Step 1 2.1"; if the edge plate surface is an inclined plane or a curved edge plate, select the vector according to "Step 1 2.2". The tool axis should have a certain inclination angle relative to the edge plate surface, and the inclination direction should be: tilted toward the back when processing the basin-facing blade body, and tilted toward the basin-facing edge plate when processing the back-facing blade body. The angle control in this step should take into account the shape and size of the blade and the size of the grinding tool and tool rod. When the reference tool axis vector cannot meet the requirements, the Cartesian coordinate system can be used to fine-tune the vector, such as Fig.21 and 22 shown.

[0096] (2) Fig.23 As shown in the figure, when grinding the entire blade profile including the front and rear edges at the same time, the tool needs to keep a relative angle with the edge plate surface at all times within the range of one circle around the blade, that is, the tool axis needs to change in real time to perform variable angle processing. Therefore, first select the normal of the edge plate surface as the tool axis direction (if the edge plate surface is a horizontal plane, select the vector according to "Step 1 2.1"; if the edge plate surface is an inclined plane or a curved edge plate, select the vector according to "Step 1 2.2"), and then control it through the inclination angle of the tool axis vector, so that the tool axis can maintain a inclination angle relative to the edge plate surface at each position of the spiral tool path, as shown in the figure. Fig.24 shown.

[0097] 4. Optimization of compressor blade root transition arc

[0098] 4.1 Compressor blade root transition arc model splitting

[0099] The blade root transfer is separated from the wheel model. The separation point should be the point where the arc is tangent to the blade body surface and the edge plate surface, such as Fig.10 and Fig.11 shown.

[0100] 4.2 Optimization of compressor blade root transition arc model

[0101] The transition arc model is prone to local overlap and intersection, which causes local tool path folding and pause during grinding, resulting in overcutting of the profile at the transition arc. If the above situation exists, the tolerance of the transition arc needs to be increased, for example: 0.002 is adjusted to 0.01, so that the transition arc has a smooth transition at the sharp edge.

[0102] 4.3 Selection and optimization of the arc cutter shaft for compressor blade root transfer

[0103] like Fig.25As shown in the figure, when grinding the blade root transition arc, the tool needs to keep a relative inclination angle with the edge plate surface within a circle, that is, the tool axis needs to change in real time to perform variable angle processing. Therefore, first select the normal of the edge plate surface as the tool axis direction (if the edge plate surface is a horizontal plane, select the vector according to "Step 1 2.1"; if the edge plate surface is an inclined plane or a curved edge plate, select the vector according to "Step 1 2.2"), and then control it through the inclination angle of the tool axis vector, so that the tool axis can maintain a inclination angle relative to the edge plate surface at each position of the spiral tool path.

[0104] The above is a detailed introduction to a compressor blade grinding model optimization method provided by the present invention. This article uses specific examples to illustrate the structure and working principle of the present invention. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A compressor blade grinding model optimization method, characterized in that: The following steps are included: Step 1: Establishment of theoretical model: Establish theoretical 3D model of compressor blade by UG 3D model design software, and construct reference knife axis vector group for selection. The model includes blade body, tenon, edge plate and transition arc of each part; Step 2: Model splitting: split the theoretical model according to the machining locations and order of CNC grinding, and split the blade into the leading edge (1), trailing edge (2), basin-facing blade body (3), back-facing blade body (4), basin-facing edge plate (5), back-facing edge plate (6), and blade root transition arc (7); Step 3: Model optimization, using UG three-dimensional model design software to optimize and reconstruct each part of the blade theoretical model; Step 4: Tool axis optimization. According to the surface features of each part of the blade, select a set of matches from the reference tool axis vectors constructed in step 1. According to the processing characteristics requirements of each part, refine the tool axis control through the Cartesian coordinate system or the spherical coordinate system.

2. The compressor blade grinding model optimization method according to claim 1, characterized in that: The edge plates in step 1 are divided into horizontal plane edge plates, inclined plane edge plates and curved surface edge plates. According to the different requirements of grinding processing faced by different types of edge plates, reference tool axis vector groups for selection are constructed respectively.

3. The compressor blade grinding model optimization method according to claim 2, characterized in that: The reference knife axis vector of the horizontal plane edge plate component is as follows: draw a straight line from the zero point of the blade coordinate system to coincide with the Zc axis, and rotate the straight line with the zero point as the axis point, and the Xc and Yc axes as the rotation axes, respectively, at an interval of 2° for multiple times to obtain two sets of reference knife axis vectors perpendicular to and parallel to the blade body direction; The reference tool axis vectors of inclined plane edge plates and curved edge plate components are as follows: three sets of isoparametric curves in the U direction and the V direction are constructed on the edge plate surface, and the geometric center point of the plane or the curved surface is found by using the intersection of the isoparametric curves. A straight line is constructed with the geometric center point as the starting point, and the direction is the normal of the edge plate surface. The starting point of the straight line is the axis point, and the U-direction / V-direction isoparametric curve at the geometric center point or the tangent of the U-direction / V-direction isoparametric curve and the edge plate surface is used as the rotation axis. A set of reference tool axis vectors perpendicular to / parallel to the blade body direction are obtained by rotating multiple times at an interval of 2°.

4. The compressor blade grinding model optimization method according to claim 1, characterized in that: The model splitting in step 2 divides the parts of the blade split as a whole into four groups for optimization, namely the leading and trailing edges of the blade, the back edge plate of the blade basin, the back blade body of the blade basin and the blade root transition arc, and then splits the four groups of models from the wheel model, and selects the segmentation points for splitting.

5. The compressor blade grinding model optimization method according to claim 4, characterized in that: The dividing points of the leading and trailing edges of the blade and the blade basin facing away from the blade body are selected at the tangent points between the blade body curved surface and the leading and trailing edges, and are split along the Zc axis direction. The leading and trailing edge models split from the leading and trailing edges of the blade are similar in width in the Xc axis direction, and the basin and back models split from the blade basin facing away from the blade body have large curvature at the edges and remain vertical along the Zc axis direction; the splitting boundary of the blade basin facing away from the edge plate is the plane or arc surface area outside the root transition arc; the splitting point of the blade root transition arc is the point where the arc is tangent to the blade body profile and the edge plate surface.

6. The compressor blade grinding model optimization method according to claim 1, characterized in that: Model optimization in step 3 The following steps are included: Step 31: Extracting curves, extracting edge curves of each group; Step 32: Surface smoothing: smoothing the curve using curve parameters; Step 33: Surface reorganization: construct a new surface from the smoothed curves and compare it with the original theoretical model to see if it is distorted. If the conditions are not met, repeat steps 31 and 32 until the requirements are met.

7. The compressor blade grinding model optimization method according to claim 6, characterized in that: The surface smoothing and curve reorganization in the model optimization step of the back edge plate of the blade basin are replaced as follows: the offset curve: the curve extracted in step 31 of the offset curve command on the surface is used, the support surface is the edge plate surface of the theoretical model, and the offset size exceeds the edge of the edge plate surface of the theoretical model; the curve reorganization: the curve extracted in step 31 and the curve offset by the offset curve are combined into a fan-shaped surface, and the surface size can completely cover the edge plate surface of the theoretical model; The model optimization of the blade root transition arc is as follows: increase the tolerance at the transition arc to make the transition arc smooth at the sharp edge.

8. The compressor blade grinding model optimization method according to claim 1 or 3, characterized in that: The specific steps for processing the leading and trailing edges of the blades in step 4 are as follows: control the swing angle of the tool axis, select a vector with a suitable inclination angle as the tool axis direction, and the tool axis should be inclined from the leading and trailing edges toward the blade body. When the reference tool axis vector cannot meet the requirements, the vector can be fine-tuned with the aid of a Cartesian coordinate system or a spherical coordinate system.

9. The compressor blade grinding model optimization method according to claim 1 or 3, characterized in that: The processing steps of the basin back edge plate and the basin back blade body in step 4 are as follows: select a vector, the tool axis has a certain inclination angle relative to the edge plate surface, and the inclination direction should be: when the basin is processed toward the blade body, it is inclined toward the back, and when the back blade body is processed, it is inclined toward the basin edge plate. When the reference tool axis vector cannot meet the requirements, the vector can be fine-tuned with the aid of the Cartesian coordinate system or the spherical coordinate system; When grinding the entire blade surface including the leading and trailing edges at the same time, a vector is selected and then controlled by the inclination angle of the tool axis vector so that the tool axis can maintain a inclination angle relative to the edge plate surface at each position of the spiral tool path.

10. The compressor blade grinding model optimization method according to claim 1 or 3, characterized in that: The blade root transfer arc tool axis is optimized as follows: during grinding, a vector is selected and controlled by the inclination angle of the tool axis vector, so that the tool axis can maintain a inclination angle relative to the edge plate surface at each position of the spiral tool path.

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