Blade profile scanning method based on actually measured blade profile normal correction

Abstract

The invention provides a blade profile scanning method based on actual measurement blade profile normal correction, which comprises the following steps: S1, selecting sections based on a blade theoretical model, and generating theoretical measurement points of different sections; s2, improving a scanning path based on the theoretical measurement point; s3, based on the improved scanning path, scanning and measuring the blade profile of each section, and outputting an actual measurement coordinate result of each measurement point; s4, calculating a normal vector of an actual measurement point based on the actual measurement coordinate result; and S5, performing radius compensation on the obtained actual measurement coordinate result of the normal vector of the actual measurement point, and outputting the compensated measurement point coordinate of the actual blade profile. According to the method, actual measurement data are obtained through scanning along the triangular waveform, and the normal of each point on the actual blade profile is approximately calculated, so that the large cosine error generated when the blade profile is measured in the current traditional uniform-section method when the deviation between a real object and a model is large is reduced, and the measurement precision of the blade profile is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engine blade detection, and in particular to a blade profile scanning method based on actual measured blade profile normal line correction. Background Art

[0002] When a three-dimensional coordinate measuring machine uses a contact spherical probe to measure points on a complex free-form surface, the normal line of the actual measured point is often replaced by the theoretical point normal line on the digital model for radius compensation, which causes cosine error.

[0003] When the machining accuracy of parts is poor, resulting in a large difference between the actual workpiece and the theoretical model, the use of the normal line on the theoretical model will produce a large cosine error. For aircraft engine blades, due to their complex surface and large changes in blade surface curvature, there is often a certain deviation between the actual part machining surface and the theoretical model.

[0004] However, currently, there is no better method to obtain the actual blade surface normal while considering the efficiency of blade profile detection. The commonly used method is still to directly use the normal on the theoretical digital model instead of the actual part surface normal, which often results in a large cosine error.

[0005] In view of this, and in order to take into account measurement efficiency, the inventors of the present application designed a blade profile scanning method based on the correction of the measured blade profile normal. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the defect of inaccurate compensation of measuring ball radius when the three-coordinate contact spherical probe adopts the equal-section method to measure blades in the prior art, and to provide a blade profile scanning method based on the actual measured blade profile normal correction.

[0007] The present invention solves the above technical problems through the following technical solutions:

[0008] The present invention provides a blade profile scanning method based on measured blade profile normal correction, which is characterized in that the scanning method comprises the following steps: 1 , Based on the blade theoretical model, select the cross section and generate theoretical measurement points of different cross sections; S 2 , based on the theoretical measurement points, improve the scanning path; S 3 , based on the improved scanning path, scan and measure the blade profiles of each section, and output the measured coordinate results of each measuring point; S 4 , based on the above measured coordinate results, calculate the normal vector of the measured point; S 5 , perform radius compensation on the measured coordinate results of the normal vector of the measured point obtained above, and output the measured point coordinates of the actual blade profile after compensation.

[0009] According to one embodiment of the present invention, the step S 1 Middle: The cross section is an isometric Z-axis coordinate cross section, and its theoretical measurement point is obtained by intercepting at a specified Z-axis height of the blade theoretical model; the blade theoretical model is a design model of the blade, and the Z-axis of the design coordinate system of the design model is parallel to the blade stacking axis and points from the blade root to the blade tip.

[0010] According to one embodiment of the present invention, the step S 1 Middle: The sections at different heights are formed by the intersection of planes with different Z coordinate values ​​specified in the detection technical requirements document and the blade model; the theoretical measurement points on the scanning path corresponding to the same section are automatically generated by dedicated software.

[0011] According to one embodiment of the present invention, the step S 1 Middle: The density of theoretical measurement points on the created cross-sectional scanning path is not less than 1 times the measurement density required by the blade profile detection technical document, including theoretical measurement points corresponding to different heights and theoretical normal vectors corresponding to each theoretical measurement point.

[0012] According to one embodiment of the present invention, the step S 2 The following steps are included: 21 , take any section as Z0, process the original theoretical scanning point set {Pnt}_Z0 composed of theoretical measurement points on the section scanning path, and obtain the improved scanning path point set {Pnt}_Z0_d; S 22 , replacing the original theoretical scanning point set {Pnt}_Z0 with the improved scanning path point set {Pnt}_Z0_d to generate an improved measurement scanning path;

[0013] S 23 Repeat the above steps for other original theoretical point sets of the cross section. 21 , the step S 22 , in order to complete the improvement of the scanning path of each section of the blade.

[0014] According to one embodiment of the present invention, the step S 21 The following steps are included: 211 , take any section as Z0, and combine the theoretical measurement points on the section scanning path into a point set {Pnt}_Z0, with the starting point of the section as Pnt_0; S 212 , add the Z coordinate value of the first theoretical measurement point Pnt_1 (x1, y1, z1) on the scanning path to the distance d01 between the section starting point Pnt_0 and the first theoretical measurement point Pnt_1 to obtain the first correction point Pnt_1_d (x1, y1, z1+d01); S 213 , keep the coordinate value of the second theoretical measurement point Pnt_2 unchanged; S 214, subtract the distance d23 between the third theoretical measurement point Pnt_3 and the second theoretical measurement point Pnt_2 from the Z coordinate value of the third theoretical measurement point Pnt_3 (x3, y3, z3) on the scanning path to obtain the third correction point Pnt_3_d (x3, y3, z3-d23); S 215 , keep the coordinate value of the fourth theoretical measurement point Pnt_4 unchanged; S 216 Repeat step S 211 To step S 215 , until the processing of the point set {Pnt}_Z0 is completed, and the improved scanning path point set {Pnt}_Z0_d is obtained.

[0015] According to one embodiment of the present invention, the step S 3 The following steps are included: 31 , Before scanning measurement, align the blade measurement coordinate system to the theoretical model coordinate system; S 32 , follow step S when scanning 2 Improved scan path execution in S 33 , turn off the probe ball radius compensation function during scanning, and the output measured coordinate results are the coordinates of the probe ball center.

[0016] According to one embodiment of the present invention, the step S 4 The following steps are included: 41 , the measured sphere center coordinate point set corresponding to section Z0 and its improved scanning path point set {Pnt}_Z0_d is {Pnt_c}_Z0_d, and the points corresponding to the theoretical measurement points on section Z0 are selected from the point set {Pnt_c}_Z0_d to calculate the measured normal vector; S 42 , calculate the measured normal vectors of the starting point Pnt_c_0, any intermediate point Pnt_c_i, and the last point Pnt_c_n in the point set {Pnt_c}_Z0_d that satisfy the corresponding theoretical measurement point on the Z0 section respectively; S 43 Repeat the above step S for the measured sphere center coordinate point set of other cross sections 41 and the step S 42 , calculate the measured normal vector of the measured point on each cross section, and normalize each measured normal vector to obtain the normalized measured normal vector.

[0017] According to one embodiment of the present invention, the step S 42The formula includes: for the starting point Pnt_c_0 in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point on the Z0 section, the normal vector of the point Pnt_c_0 is determined by the plane normal fitted by the point itself and its subsequent two points Pnt_c_1 and Pnt_c_2; for any intermediate point Pnt_c_i in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point on the Z0 section, the plane fitted by the point Pnt_c_i and its two preceding points Pnt_c_i-2 and Pnt_c_i-1 is Plan_i -1, the plane fitted by the point Pnt_c_i and its subsequent two points Pnt_c_i+1 and Pnt_c_i+2 is Plan_i, and the normal vector of the point Pnt_c_i is obtained by vector synthesis of the normals of the plane Plan_i-1 and the plane Plan_i; for the last point Pnt_c_n in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point and is located on the Z0 section, the normal vector of the point Pnt_c_n is determined by the plane normal fitted by the point itself and its two preceding points Pnt_c_n-1 and Pnt_c_n-2.

[0018] According to one embodiment of the present invention, the step S 5 The following steps are included: 51 , replacing the theoretical normal vector of the point on the blade theoretical model with the normalized measured normal vector; S 52 , for any point Pnt(x,y,z) and the normalized measured normal vector v(i,j,k) of the point, given the radius value R, calculate the compensated point Pnt_v(x+R*i, y+R*j, z+R*k); S 53 , perform radius compensation calculation on the measured sphere center coordinates on each measuring section, and output the measured point coordinates of the actual blade profile after compensation.

[0019] The positive and progressive effects of the present invention are:

[0020] The blade profile scanning method based on measured blade profile normal correction of the present invention has at least the following advantages:

[0021] First, a scanning strategy along a triangular waveform with the blade profile section to be measured as the center is proposed, which improves the existing blade profile section scanning method.

[0022] Second, based on the proposed scanning strategy, an approximate calculation method for the true normal of the blade profile is given.

[0023] 3. This scanning method only scans once along the equal section. While ensuring the measurement efficiency, it obtains a normal line that is closer to the real one than the traditional equal section method, reduces the cosine error, and improves the compensation accuracy of the measuring ball radius. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other features, properties and advantages of the present invention will become more apparent through the following description in conjunction with the accompanying drawings and embodiments, in which the same reference numerals always represent the same features, wherein:

[0025] Figure 1 It is a schematic diagram of the implementation process of the blade profile scanning method based on the measured blade profile normal correction of the present invention.

[0026] Figure 2 It is a schematic diagram of the equal-section measurement scanning path of the improved blade profile scanning method based on the actual measured blade profile normal correction of the present invention.

[0027] Figure 3A It is a schematic diagram of normal calculation of the starting point Pnt_c_0 on the blade profile section of the blade profile scanning method based on the actual measured blade profile normal correction of the present invention.

[0028] Figure 3B It is a schematic diagram of normal calculation of any middle point Pnt_c_i on the blade profile cross section of the blade profile scanning method based on the actual measured blade profile normal correction of the present invention.

[0029] Figure 3C It is a schematic diagram of normal calculation of the last point Pnt_c_n on the blade profile section of the blade profile scanning method based on measured blade profile normal correction of the present invention. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Reference will now be made in detail to preferred embodiments of the present invention, examples of which are shown in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to represent the same or similar parts.

[0032] Furthermore, although the terms used in the present invention are selected from well-known and commonly used terms, some terms mentioned in the present invention specification may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this document.

[0033] Furthermore, it is required that the present invention be understood not only by the actual terms used but also by the meanings connoted by each term.

[0034] The purpose of the present invention is to solve the problem of cosine error in measuring ball radius compensation caused by using theoretical normals instead of actual blade profile normals in three-coordinate contact spherical probes, and the problem that traditional three-coordinate contact equal-section scanning measurement cannot calculate the three-dimensional normals of the blade profile.

[0035] like Figure 1 As shown, the present invention provides a blade profile scanning method based on measured blade profile normal correction, the scanning method comprising the following steps:

[0036] Step S 1 , Based on the blade theoretical model, select the cross section and generate theoretical measurement points of different cross sections.

[0037] Step S 2 , based on the theoretical measurement points, improving the scanning path.

[0038] Step S 3 Based on the improved scanning path mentioned above, scan and measure the blade profile of each section, and output the measured coordinate results of each measuring point.

[0039] Step S 4 , Based on the above measured coordinate results, calculate the normal vector of the measured point.

[0040] Step S 5 , perform radius compensation on the measured coordinate results of the normal vector of the measured point obtained above, and output the measured point coordinates of the actual blade profile after compensation.

[0041] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S 1 middle:

[0042] The cross section is an isometric Z-axis coordinate cross section, and its theoretical measurement point is obtained by intercepting at a specified Z-axis height of the blade theoretical model.

[0043] The blade theoretical model is a design model of the blade. The Z axis of the design coordinate system of the design model is parallel to the blade stacking axis and points from the blade root to the blade tip.

[0044] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S 1 middle:

[0045] The cross sections at different heights are formed by the intersection of planes with different Z coordinate values ​​specified in the detection technical requirement document and the blade model.

[0046] The theoretical measurement points on the scanning path corresponding to the same cross section are automatically generated by dedicated software, such as the nom file generated by PCDMIS-BLADE software, which includes theoretical measurement points corresponding to different heights and the corresponding normal vectors of each point.

[0047] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S 1 middle:

[0048] The density of theoretical measurement points on the created cross-sectional scanning path is not less than 1 times the measurement density required by the blade profile detection technical document, including theoretical measurement points corresponding to different heights and the corresponding normal vectors of each point.

[0049] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S 2 The steps include:

[0050] Step S 21 , take any cross section as Z0, process the original theoretical scanning point set {Pnt}_Z0 composed of theoretical measurement points on the cross section scanning path, and obtain the improved scanning path point set {Pnt}_Z0_d.

[0051] Step S 22 , replace the original theoretical scanning point set {Pnt}_Z0 with the improved scanning path point set {Pnt}_Z0_d to generate an improved measurement scanning path.

[0052] Step S 23 Repeat the above steps for other original theoretical point sets of the cross section. 21 , the step S 22 , in order to complete the improvement of the scanning path of each section of the blade.

[0053] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S 21 The steps include:

[0054] Step S 211 , take any section as Z0, and organize the theoretical measurement points on the section scanning path into a point set {Pnt}_Z0, with the starting point of the section being Pnt_0.

[0055] Step S 212 , add the Z coordinate value of the first theoretical measurement point Pnt_1 (x1, y1, z1) on the scanning path to the distance d01 between the section starting point Pnt_0 and the first theoretical measurement point Pnt_1 to obtain the first correction point Pnt_1_d (x1, y1, z1+d01).

[0056] Step S213 , keep the coordinate value of the second theoretical measurement point Pnt_2 unchanged.

[0057] Step S 214 , subtract the distance d23 between the third theoretical measurement point Pnt_3 and the second theoretical measurement point Pnt_2 from the Z coordinate value of the third theoretical measurement point Pnt_3 (x3, y3, z3) on the scanning path to obtain the third correction point Pnt_3_d (x3, y3, z3-d23).

[0058] Step S 215 , keep the coordinate value of the fourth theoretical measurement point Pnt_4 unchanged.

[0059] Step S 216 Repeat step S 211 To step S 215 , until the processing of the point set {Pnt}_Z0 is completed, and the improved scanning path point set {Pnt}_Z0_d is obtained.

[0060] like Figure 2 As shown, C represents the blade body contour, the dotted line represents the position of the section Zi, L1 is the original theoretical scanning path of the section Zi, and L2 is the improved measurement scanning path of the section Zi.

[0061] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S 3 The following steps are included:

[0062] Step S 31 ,Before scanning measurement, align the blade measurement coordinate system to the theoretical model coordinate system.

[0063] Step S 32 , follow step S when scanning 2 Improved scan path execution in .

[0064] Step S 33 , turn off the probe ball radius compensation function during scanning, and the output measured coordinate results are the coordinates of the probe ball center.

[0065] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S 4 The steps include:

[0066] Step S 41 The measured sphere center coordinate point set corresponding to section Z0 and its improved scanning path point set {Pnt}_Z0_d is {Pnt_c}_Z0_d. In the point set {Pnt_c}_Z0_d, the points corresponding to the theoretical measurement points on section Z0 are selected to calculate the measured normal vectors.

[0067] Step S 42 , calculate the measured normal vectors of the starting point Pnt_c_0, any intermediate point Pnt_c_i, and the last point Pnt_c_n in the point set {Pnt_c}_Z0_d that satisfy the corresponding theoretical measurement point on the Z0 section.

[0068] Step S 43 Repeat the above step S for the measured sphere center coordinate point set of other cross sections 41 and the step S 42 , calculate the measured normal vector of the measured point on each cross section, and normalize each measured normal vector to obtain the normalized measured normal vector.

[0069] like Figure 3A to Figure 3C As shown in the figure, it is a schematic diagram of the calculation of the normal line of a point on the blade section under different conditions.

[0070] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S 42 Included:

[0071] like Figure 3A As shown, for the starting point Pnt_c_0 in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point and is located on the Z0 section, the normal vector of the point Pnt_c_0 is determined by the plane normal fitted by the point itself and its subsequent two points Pnt_c_1 and Pnt_c_2.

[0072] like Figure 3B As shown, for any intermediate point Pnt_c_i in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point on the Z0 section, the plane fitted by the point Pnt_c_i and its two preceding points Pnt_c_i-2 and Pnt_c_i-1 is Plan_i-1, and the plane fitted by the point Pnt_c_i and its two subsequent points Pnt_c_i+1 and Pnt_c_i+2 is Plan_i, and the normal vector of the point Pnt_c_i is obtained by vector synthesis of the normal lines of the plane Plan_i-1 and the plane Plan_i.

[0073] like Figure 3C As shown, for the last point Pnt_c_n in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point and is located on the Z0 section, the normal vector of the point Pnt_c_n is determined by the plane normal fitted by the point itself and its two preceding points Pnt_c_n-1 and Pnt_c_n-2.

[0074] As a preferred implementation of the blade profile scanning method based on measured blade profile normal correction of the present invention, the step S5 The steps include:

[0075] Step S 51 , performing radius compensation on the spherical center coordinates of the above-obtained measured normal vector, that is, replacing the theoretical normal vector of the point on the blade theoretical model with the normalized measured normal vector.

[0076] Step S 52 , For any point Pnt(x,y,z) and the normalized measured normal vector v(i,j,k) of the point, given the radius value R, calculate the compensated point Pnt_v(x+R*i, y+R*j, z+R*k).

[0077] Step S 53 , perform radius compensation calculation on the measured sphere center coordinates on each measuring section, and output the measured point coordinates of the actual blade profile after compensation.

[0078] The present invention is based on a blade profile scanning method for correcting measured blade profile normals, improves the conventional equal-section method in which the normal on a theoretical model is used instead of the real normal to compensate for the cosine error of the measuring sphere radius caused by the contact measurement of blade profiles using a three-coordinate spherical needle. The conventional equal-section method obtains measured data by scanning along a triangular waveform to approximately calculate the normals of each point on the actual blade profile, thereby reducing the large cosine error generated when measuring blade profiles using the current conventional equal-section method when the deviation between the actual object and the model is large, thereby improving the measurement accuracy of the blade profile.

[0079] In summary, the blade profile scanning method based on measured blade profile normal correction of the present invention has the following advantages:

[0080] First, a scanning strategy along a triangular waveform with the blade profile section to be measured as the center is proposed, which improves the existing blade profile section scanning method.

[0081] Second, based on the proposed scanning strategy, an approximate calculation method for the true normal of the blade profile is given.

[0082] 3. This scanning method only scans once along the equal section. While ensuring the measurement efficiency, it obtains a normal line that is closer to the real one than the traditional equal section method, reduces the cosine error, and improves the compensation accuracy of the measuring ball radius.

[0083] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A blade profile scanning method based on measured blade profile normal correction, characterized in that: The scanning method comprises the following steps: S1. Based on the blade theoretical model, select the cross section and generate theoretical measurement points of different cross sections; S2, improving the scanning path based on the theoretical measurement points; S3, based on the improved scanning path, scan and measure the blade profiles of each section, and output the measured coordinate results of each measuring point; S4. Calculate the normal vector of the measured point based on the measured coordinate results; S5. Perform radius compensation on the measured coordinate results of the measured point normal vector obtained above, and output the measured point coordinates of the actual blade profile after compensation.

2. The blade profile scanning method based on measured blade profile normal correction according to claim 1, characterized in that: In step S1: The cross section is a cross section with equal Z-axis coordinates, and its theoretical measurement point is obtained by intercepting at a specified Z-axis height of the blade theoretical model; The blade theoretical model is a design model of the blade. The Z axis of the design coordinate system of the design model is parallel to the blade stacking axis and points from the blade root to the blade tip.

3. The blade profile scanning method based on measured blade profile normal correction according to claim 2, characterized in that: In step S1: The cross sections at different heights are formed by the intersection of planes with different Z coordinate values ​​specified in the inspection technical requirements document and the blade model; Theoretical measurement points on the scanning path corresponding to the same cross section are automatically generated by dedicated software.

4. The blade profile scanning method based on measured blade profile normal correction according to claim 3, characterized in that: In step S1: The density of theoretical measurement points on the created cross-sectional scanning path is not less than 1 times the measurement density required by the blade profile detection technical document, including theoretical measurement points corresponding to different heights and theoretical normal vectors corresponding to each theoretical measurement point.

5. The blade profile scanning method based on measured blade profile normal correction according to claim 1, characterized in that: The step S2 comprises the following steps: S 21 , take any cross section as Z0, process the original theoretical scanning point set {Pnt}_Z0 composed of theoretical measurement points on the cross section scanning path, and obtain the improved scanning path point set {Pnt}_Z0_d; S 22 , replacing the original theoretical scanning point set {Pnt}_Z0 with the improved scanning path point set {Pnt}_Z0_d to generate an improved measurement scanning path; S 23 Repeat the above steps for other original theoretical point sets of the cross section. 21 , the step S 22 , in order to complete the improvement of the scanning path of each section of the blade.

6. The blade profile scanning method based on measured blade profile normal correction according to claim 5, characterized in that: The step S 21 The steps include: S 211 , take any section as Z0, and combine the theoretical measurement points on the section scanning path into a point set {Pnt}_Z0, with the starting point of the section as Pnt_0; S 212 , add the Z coordinate value of the first theoretical measurement point Pnt_1 (x1, y1, z1) on the scanning path to the distance d01 between the section starting point Pnt_0 and the first theoretical measurement point Pnt_1 to obtain the first correction point Pnt_1_d (x1, y1, z1+d01); S 213 , keep the coordinate value of the second theoretical measurement point Pnt_2 unchanged; S 214 , subtract the distance d23 between the third theoretical measurement point Pnt_3 and the second theoretical measurement point Pnt_2 from the Z coordinate value of the third theoretical measurement point Pnt_3 (x3, y3, z3) on the scanning path to obtain a third correction point Pnt_3_d (x3, y3, z3-d23); S 215 , keep the coordinate value of the fourth theoretical measurement point Pnt_4 unchanged; S 216 Repeat step S 211 To step S 215 , until the processing of the point set {Pnt}_Z0 is completed, and the improved scanning path point set {Pnt}_Z0_d is obtained.

7. The blade profile scanning method based on measured blade profile normal correction according to claim 6, characterized in that: The step S3 includes the following steps: S 31 ,Before scanning measurement, align the blade measurement coordinate system to the theoretical model coordinate system; S 32 , when scanning, the scanning path improved in step S2 is followed; S 33 , turn off the probe ball radius compensation function during scanning, and the output measured coordinate results are the coordinates of the probe ball center.

8. The blade profile scanning method based on measured blade profile normal correction according to claim 7, characterized in that: The step S4 comprises the following steps: S 41 , the measured sphere center coordinate point set corresponding to the section Z0 and its improved scanning path point set {Pnt}_Z0_d is {Pnt_c}_Z0_d, and the points corresponding to the theoretical measurement points on the section Z0 are selected from the point set {Pnt_c}_Z0_d to calculate the measured normal vector; S 42 , calculate the measured normal vectors of the starting point Pnt_c_0, any intermediate point Pnt_c_i, and the last point Pnt_c_n in the point set {Pnt_c}_Z0_d that satisfy the corresponding theoretical measurement point on the Z0 section respectively; S 43 Repeat the above step S for the measured sphere center coordinate point set of other cross sections 41 and the step S 42 , calculate the measured normal vector of the measured point on each cross section, and normalize each measured normal vector to obtain the normalized measured normal vector.

9. The blade profile scanning method based on measured blade profile normal correction according to claim 8, characterized in that: The step S 42 Included: For the starting point Pnt_c_0 in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point on the Z0 section, the normal vector of the point Pnt_c_0 is determined by the plane normal fitted by the point itself and its subsequent two points Pnt_c_1 and Pnt_c_2; For any intermediate point Pnt_c_i in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point on the Z0 section, the plane fitted by the point Pnt_c_i and its two preceding points Pnt_c_i-2 and Pnt_c_i-1 is Plan_i-1, the plane fitted by the point Pnt_c_i and its two subsequent points Pnt_c_i+1 and Pnt_c_i+2 is Plan_i, and the normal vector of the point Pnt_c_i is obtained by synthesizing the normal lines of the plane Plan_i-1 and the plane Plan_i according to the vector; For the last point Pnt_c_n in the point set {Pnt_c}_Z0_d that satisfies the corresponding theoretical measurement point on the Z0 section, the normal vector of the point Pnt_c_n is determined by the plane normal fitted by the point itself and its two preceding points Pnt_c_n-1 and Pnt_c_n-2.

10. The blade profile scanning method based on measured blade profile normal correction according to claim 8, characterized in that: The step S5 comprises the following steps: S 51 , replacing the theoretical normal vector of the point on the blade theoretical model with the normalized measured normal vector; S 52 , For any point Pnt(x,y,z) and the normalized measured normal vector v(i,j,k) of the point, given the radius value R, calculate the compensated point Pnt_v(x+R*i, y+R*j, z+R*k); S 53 , perform radius compensation calculation on the measured sphere center coordinates on each measuring section, and output the measured point coordinates of the actual blade profile after compensation.

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