Blade profile scanning method based on measured profile normal correction

Abstract

The application provides a kind of blade profile scanning method based on measured profile normal correction, comprising the following steps: S1, based on blade theoretical model, select cross section, generate different cross section theoretical measuring point;S2, based on the theoretical measuring point, improve scanning path;S3, based on the improved scanning path, scan each cross section profile, output the measured coordinate result of each measuring point;S4, based on the measured coordinate result, calculate the measured point normal vector;S5, the measured coordinate result of the measured point normal vector obtained above is compensated by radius, and the measuring point coordinate of the actual blade profile after compensation is output.The method of the application obtains measured data by scanning along triangular waveform to approximate calculate the normal of each point on the actual blade profile, thereby reducing the large cosine error generated by measuring blade profile when the current traditional equal cross section method is used in the case of large deviation between actual object and model, and improving the measurement accuracy of blade profile.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine blade detection, and specifically relates to a blade profile scanning method based on measured profile normal correction. BACKGROUND

[0002] When a three-coordinate measuring machine adopts a contact type spherical probe to carry out point measurement on a complex free-form surface, a cosine error is often generated by using a theoretical point normal on a numerical model to replace an unknown measured point normal and carrying out radius compensation.

[0003] When the machining precision of a part is poor, resulting in a large difference between an actual workpiece and a theoretical model, a large cosine error will be generated by using the normal on the theoretical model.

[0004] At present, in consideration of blade profile detection efficiency, there is no good method to obtain the actual blade surface normal, and the commonly used method is still to directly use the normal on the theoretical numerical model to replace the actual part surface normal, so a large cosine error is often generated.

[0005] In view of this, in order to consider the measurement efficiency, the inventors of the present application have designed a blade profile scanning method based on measured profile normal correction. SUMMARY

[0006] The present application aims to solve the technical problem of inaccurate radius compensation of a three-coordinate contact type spherical probe when measuring a blade by using an equal cross-section method in the prior art, and provides a blade profile scanning method based on measured profile normal correction.

[0007] The present application solves the above technical problem by the following technical scheme:

[0008] The present application provides a blade profile scanning method based on measured profile normal correction, which is characterized in that the scanning method comprises the following steps: S1, based on a blade theoretical model, selecting a cross-section to generate theoretical measurement points of different cross-sections; S2, based on the theoretical measurement points, improving a scanning path; S3, based on the improved scanning path, scanning and measuring each cross-section profile to output measured coordinate results of each measurement point; S4, based on the measured coordinate results, calculating a measured point normal vector; and S5, carrying out radius compensation on the measured coordinate results of the obtained measured point normal vector to output the measurement point coordinates of the compensated actual blade profile.

[0009] According to one embodiment of the present application, in the step S1: the cross section is an equal-Z-axis coordinate cross section, and the theoretical measurement point is obtained by cutting the 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 stacking axis of the blade and points from the blade root to the blade tip.

[0010] According to one embodiment of the present application, in the step S1: the cross sections at different heights are formed by intersecting the planes with different Z coordinate values specified in the detection technical requirement file with the blade model; and the theoretical measurement points on the scanning path corresponding to the same cross section are automatically generated by the special software.

[0011] According to one embodiment of the present application, in the step S1: the density of the theoretical measurement points on the created cross section scanning path is not less than 1 times the measurement density required by the blade airfoil detection technical file, including the theoretical measurement points corresponding to different heights and the theoretical normal vectors corresponding to each theoretical measurement point.

[0012] According to one embodiment of the present application, the step S2 comprises the following steps: 21 , taking an arbitrary cross section as Z0, processing the original theoretical scanning point set {Pnt}_Z0 on the cross section scanning path to obtain an 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 , repeating the step S 21 , the step S 22 , to complete the improvement of the cross section scanning path of the blade.

[0014] According to one embodiment of the present application, the step S 21 comprises the following steps: 211 , taking an arbitrary cross section as Z0, and taking the point set {Pnt}_Z0 composed of the theoretical measurement points on the cross section scanning path, and the cross section starting point is Pnt_0;S 212 , adding 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 cross section starting point Pnt_0 and the first theoretical measurement point Pnt_1 to obtain the first corrected point Pnt_1_d(x1, y1, z1+d01);S 213 , keeping the second theoretical measurement point Pnt_2 coordinate value unchanged;S 214, subtracting 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 modified point Pnt_3_d(x3, y3, z3-d23);S 215 , keeping the fourth theoretical measurement point Pnt_4 coordinate value unchanged;S 216 , repeating the step S 211 to the step S 215 until the processing of the point set {Pnt}_Z0 is completed, and an improved scanning path point set {Pnt}_Z0_d is obtained.

[0015] According to an embodiment of the present application, the step S3 comprises the following steps: S 31 , before scanning and measuring, aligning the blade measurement coordinate system to the theoretical model coordinate system;S 32 , performing according to the improved scanning path in step S2 during scanning;S 33 , turning off the probe radius compensation function during scanning, and outputting the measured coordinate result as the probe center coordinate.

[0016] According to an embodiment of the present application, the step S4 comprises the following steps: S 41 , the measured probe center coordinate point set corresponding to the improved scanning path point set {Pnt}_Z0_d of the cross section Z0 is {Pnt_c}_Z0_d, and the corresponding theoretical measurement point located on the cross section Z0 is selected in the point set {Pnt_c}_Z0_d to calculate the measured normal vector;S 42 , calculating the measured normal vector of the starting point Pnt_c_0, any certain intermediate point Pnt_c_i, and the last point Pnt_c_n in the point set {Pnt_c}_Z0_d which satisfy that the corresponding theoretical measurement point is located on the cross section Z0;S 43 , repeating the step S 41 and the step S 42 for the measured probe center coordinate point set of other cross sections to calculate the measured normal vector of the measured point on each cross section, and normalizing each measured normal vector to obtain the normalized measured normal vector.

[0017] According to an embodiment of the present application, the step S 42The normal vector of the point Pnt_c_0 is determined by the normal line of the plane 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 that the corresponding theoretical measurement point is located on the Z0 section, the plane fitted by the two previous points Pnt_c_i-2 and Pnt_c_i-1 of the point Pnt_c_i is Plan_i-1, the plane fitted by the two subsequent points Pnt_c_i+1 and Pnt_c_i+2 of the point Pnt_c_i is Plan_i, and the normal vector of the point Pnt_c_i is obtained by vector composition of the normal lines of the planes Plan_i-1 and Plan_i; the normal vector of the last point Pnt_c_n in the point set {Pnt_c}_Z0_d that satisfies that the corresponding theoretical measurement point is located on the Z0 section is determined by the normal line of the plane fitted by the point itself and its previous two points Pnt_c_n-1 and Pnt_c_n-2.

[0018] According to one embodiment of the present application, the step S5 comprises the following steps: 51 replacing the theoretical normal vector of the point on the blade theoretical model with the normalized measured normal vector; 52 for any point Pnt(x, y, z) and the normalized measured normal vector v(i, j, k) of the point, a radius value R is given, and a compensated point Pnt_v(x+R*i, y+R*j, z+R*k) is calculated; 53 the measured spherical center coordinates on each measurement section are subjected to radius compensation calculation, and the measurement point coordinates of the compensated actual blade profile are output.

[0019] The positive progress effect of the present application is that:

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

[0021] I. A scanning strategy is proposed, which takes the to-be-measured section of the blade profile as the center and follows a triangular waveform, and the existing blade profile section scanning method is improved.

[0022] II. Based on the proposed scanning strategy, an approximate calculation method of the real normal of the blade profile is given.

[0023] III. The scanning method only scans along the section once, and in the case of ensuring the measurement efficiency, the real normal is obtained, the cosine error is reduced, and the measurement accuracy of the spherical radius compensation is improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] The above and other features, aspects and advantages of the present application will become more apparent from the following description in conjunction with the accompanying drawings, in which like reference numerals refer to like elements throughout the drawings, and in which:

[0025] Figure 1 is the implementation flow diagram of the blade profile scanning method based on the measured profile normal correction of the present application.

[0026] Figure 2 is the improved isometric section measurement scanning path diagram of the blade profile scanning method based on the measured profile normal correction of the present application.

[0027] Figure 3A is the normal line calculation diagram of the starting point Pnt_c_0 on the profile section of the blade profile scanning method based on the measured profile normal correction of the present application.

[0028] Figure 3B is the normal line calculation diagram of any intermediate point Pnt_c_i on the profile section of the blade profile scanning method based on the measured profile normal correction of the present application.

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

[0030] In order to make the above objectives, features and advantages of the present application more apparent, the specific embodiments of the present application will be described in detail below in conjunction with the accompanying drawings.

[0031] Reference will now be made in detail to the embodiments of the present application, examples of which are illustrated in the accompanying drawings. The detailed description of the present application will be made in detail with reference to the preferred embodiments of the present application, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0032] In addition, although the terms used in the present application are selected from the commonly used terms, some of the terms mentioned in the specification of the present application can be selected by the applicant according to his or her judgment, and the detailed meanings thereof are described in the relevant part of the description.

[0033] In addition, the present application is required to be understood not only by the actual terms used, but also by the meanings implied by each term.

[0034] The purpose of the present application is to solve the problem of the measured ball radius compensation cosine error caused by replacing the actual blade profile normal with the theoretical normal of the three-coordinate contact spherical probe, and the problem that the three-dimensional normal of the blade profile cannot be calculated by the traditional three-coordinate contact isometric section scanning measurement.

[0035] As shown in Figure 1 The present application provides a kind of based on measured blade profile normal correction blade profile scanning method, the scanning method includes the following steps:

[0036] Step S1, based on blade theoretical model, select cross section, generate different cross section theoretical measurement point.

[0037] Step S2, based on the theoretical measurement point, improve scanning path.

[0038] Step S3, based on the improved scanning path described above, scan each cross section blade profile, output the measured coordinate result of each measurement point.

[0039] Step S4, based on the measured coordinate result described above, calculate measured point normal vector.

[0040] Step S5, the measured coordinate result of the measured point normal vector obtained above is compensated by radius, and the measurement point coordinate of the actual blade profile after compensation is output.

[0041] As a preferred embodiment of the blade profile scanning method based on measured blade profile normal correction of the present application, in the step S1:

[0042] The cross section is equal Z-axis coordinate cross section, and the theoretical measurement point is obtained by cutting at the specified Z-axis height of blade theoretical model.

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

[0044] As a preferred embodiment of the blade profile scanning method based on measured blade profile normal correction of the present application, in the step S1:

[0045] The cross section of different height is formed by the intersection of plane with different Z coordinate values specified according to detection technical requirement document and blade model.

[0046] The theoretical measurement point on scanning path corresponding to the same cross section is automatically generated by special software, such as nom file generated by PCDMIS-BLADE software, that is, including different height corresponding theoretical measurement point and corresponding normal vector of each point.

[0047] As a preferred embodiment of the blade profile scanning method based on measured blade profile normal correction of the present application, in the step S1:

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

[0049] As a preferred embodiment of the blade profile scanning method based on the measured profile normal correction of the present application, the step S2 comprises the following steps:

[0050] Step S 21 , taking an arbitrary cross section as Z0, processing the original theoretical scanning point set {Pnt}_Z0 composed of the theoretical measurement points on the cross section scanning path to obtain the improved scanning path point set {Pnt}_Z0_d.

[0051] Step 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.

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

[0053] As a preferred embodiment of the blade profile scanning method based on the measured profile normal correction of the present application, the step S 21 comprises the following steps:

[0054] Step S 211 , taking an arbitrary cross section as Z0, processing the original theoretical scanning point set {Pnt}_Z0 composed of the theoretical measurement points on the cross section scanning path to obtain the improved scanning path point set {Pnt}_Z0_d.

[0055] Step S 212 , adding 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 cross section starting point Pnt_0 and the first theoretical measurement point Pnt_1 to obtain the first corrected point Pnt_1_d(x1, y1, z1+d01).

[0056] Step S 213 , keeping the second theoretical measurement point Pnt_2 coordinate value unchanged.

[0057] Step S 214 , subtracting 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 corrected point Pnt_3_d(x3, y3, z3-d23).

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

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

[0060] As shown in Figure 2 , C represents the blade profile, the dashed line represents the position of the cross section Zi, L1 is the original theoretical scanning path of the cross section Zi, and L2 is the improved measured scanning path of the cross section Zi.

[0061] As a preferred embodiment of the blade profile scanning method based on the measured blade profile normal correction, the step S3 comprises the following steps:

[0062] The step S 31 , before scanning measurement, align the blade measurement coordinate system to the theoretical model coordinate system.

[0063] The step S 32 , during scanning, perform according to the improved scanning path in the step S2.

[0064] The step S 33 , during scanning, turn off the ball radius compensation function, and the output measured coordinate result is the ball center coordinate.

[0065] As a preferred embodiment of the blade profile scanning method based on the measured blade profile normal correction, the step S4 comprises the following steps:

[0066] The step S 41 , the measured ball center coordinate point set corresponding to the cross section Z0 and the improved scanning path point set {Pnt}_Z0_d of the cross section Z0 is {Pnt_c}_Z0_d, and the point corresponding to the theoretical measurement point located on the cross section Z0 is selected in the point set {Pnt_c}_Z0_d for the calculation of the measured normal vector.

[0067] The step S 42 , the measured normal vector of each of the starting point Pnt_c_0, any certain intermediate point Pnt_c_i, and the last point Pnt_c_n in the point set {Pnt_c}_Z0_d which satisfy that the corresponding theoretical measurement point is located on the cross section Z0 is calculated.

[0068] The step S 43 , the measured ball center coordinate point set of other cross sections repeats the step S 41 and the step S 42 , the measured normal vector of the measured point on each cross section is calculated, and each measured normal vector is normalized to obtain the normalized measured normal vector.

[0069] As shown in Figures 3A-3CThe diagram shown illustrates the calculation of point normals on the blade section under different conditions.

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

[0071] like Figure 3A As shown, for the starting point Pnt_c_0 in the point set {Pnt_c}_Z0_d that satisfies the condition that the corresponding theoretical measurement point 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 two subsequent 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 condition that the corresponding theoretical measurement point is located on the Z0 section, the plane fitted by 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 point Pnt_c_i and its two subsequent points Pnt_c_i+1 and Pnt_c_i+2 is Plan_i. The normal vector of point Pnt_c_i is obtained by vector synthesis of the normals of plane Plan_i-1 and 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 condition that the corresponding theoretical measurement point 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] In a preferred embodiment of the blade shape scanning method based on measured blade shape normal correction of the present invention, step S5 includes the following steps:

[0075] Step S 51 The center coordinates of the sphere obtained above are compensated for by radius compensation, that is, the theoretical normal vectors of the points on the blade theoretical model are replaced with the normalized measured normal vectors.

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

[0077] Step S 53The measured ball center coordinates on each measuring section are compensated in radius, and the compensated measured point coordinates of the actual blade profile are output.

[0078] The blade profile scanning method based on measured profile normal correction improves the cosine error caused by the radius compensation of the measuring ball when the traditional equal-section method is used to measure the blade profile by the three-coordinate spherical needle contact, and the normal on the theoretical model is replaced by the real normal. The normal of each point on the actual blade profile is calculated by the measured data obtained by the triangular waveform scanning, so as to reduce the large cosine error caused by the traditional equal-section method when the deviation between the actual object and the model is large, and improve the measurement accuracy of the blade profile.

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

[0080] I. A scanning strategy is proposed, which takes the measured section of the blade profile as the center and scans along the triangular waveform, and the existing equal-section scanning method of the blade profile is improved.

[0081] II. Based on the proposed scanning strategy, an approximate calculation method of the real normal of the blade profile is given.

[0082] III. The scanning method only scans along the equal-section once, and in the case of ensuring the measurement efficiency, the real normal is obtained compared with the traditional equal-section method, the cosine error is reduced, and the radius compensation accuracy of the measuring ball is improved.

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

Claims

1. A method for blade profile scanning based on a measured profile normal correction, characterized by, The scanning method comprises the following steps: S1. Selecting a cross section based on a blade theoretical model to generate theoretical measurement points of different cross sections; S2. Improving a scanning path based on the theoretical measurement points; S3. Scanning and measuring each cross section blade profile based on the improved scanning path, and outputting measured coordinate results of each measurement point; S4. Calculating a measured point normal vector based on the measured coordinate results; S5. Performing radius compensation on the measured coordinate results of the obtained measured point normal vector, and outputting measurement point coordinates of the actual blade profile after compensation. The step S2 comprises the following steps: S 21 , taking any cross section as Z0, the original theoretical scanning point set {Pnt}_Z0 composed of the theoretical measurement points on the cross section scanning path is processed to obtain the improved scanning path point set {Pnt}_Z0_d; S 22 , the improved measurement scanning path is generated by replacing the original theoretical scanning point set {Pnt}_Z0 with the improved scanning path point set {Pnt}_Z0_d. S 23 , repeating the step S 21 , the step S 22 , to complete the improvement of the scanning path of each section of the blade. The step S 21 comprising the steps of: S 211 , take any cross section as Z0, the set of theoretical measurement points on the cross section scanning path is {Pnt}_Z0, and the cross section starting point is Pnt_0; S 212 , the Z coordinate value of the first theoretical measurement point Pnt_1(x1, y1, z1) on the scanning path is added to the interval d01 between the cross-section starting point Pnt_0 and the first theoretical measurement point Pnt_1, to obtain the first corrected point Pnt_1_d(x1, y1, z1+d01); S 213 , keeping the second theoretical measurement point Pnt_2 coordinate value unchanged; S 214 , subtracting the Z coordinate value of the third theoretical measurement point Pnt_3(x3, y3, z3) on the scanning path from the distance d23 between the third theoretical measurement point Pnt_3 and the second theoretical measurement point Pnt_2, to obtain a third corrected point Pnt_3_d(x3, y3, z3-d23); S 215 , keeping the fourth theoretical measurement point Pnt_4 coordinate value unchanged; S 216 , repeat the step S 211 to the step S 215 until the processing of the point set {Pnt}_Z0 is completed, and an improved scanning path point set {Pnt}_Z0_d is obtained. The step S4 comprises the following steps: S 41 The measured spherical center coordinate point set corresponding to the improved scanning path point set {Pnt}_Z0_d of the cross section Z0 is {Pnt_c}_Z0_d. In the point set {Pnt_c}_Z0_d, the point corresponding to the theoretical measurement point located on the cross section Z0 is selected to calculate the measured normal vector. S 42 , the measured normal vector of the starting point Pnt_c_0, the measured normal vector of the any intermediate point Pnt_c_i, and the measured normal vector of the last point Pnt_c_n in the point set {Pnt_c}_Z0_d are calculated respectively. S 43 , repeating the step S 41 and the step S 42 , calculating the measured normal vectors of the measured points on each section, and normalizing each measured normal vector to obtain a normalized measured normal vector; The step S 42 includes: For a starting point Pnt_c_0 in the point set {Pnt_c}_Z0_d that satisfies that the corresponding theoretical measurement point is located on the Z0 cross section, the normal vector of the point Pnt_c_0 is determined by the normal of a plane 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 that the corresponding theoretical measurement point is located on the Z0 cross section, the plane fitted by the point Pnt_c_i and its previous two 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 composition of the normals of the planes Plan_i-1 and Plan_i; For a last point Pnt_c_n in the point set {Pnt_c}_Z0_d that satisfies that the corresponding theoretical measurement point is located on the Z0 cross section, the normal vector of the point Pnt_c_n is determined by the normal of a plane fitted by the point itself and its previous two points Pnt_c_n-1 and Pnt_c_n-2.

2. The blade profile scanning method based on the measured profile normal correction of claim 1, wherein, In the step S1: The cross section is an equal-Z-axis-coordinate cross section, and the theoretical measurement points are obtained by cutting the blade theoretical model at a specified Z-axis height; The blade theoretical model is a design model of the blade, and the design coordinate system Z-axis 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 the measured profile normal correction of claim 2, wherein, In the step S1: The cross sections at different heights are formed by intersecting planes with different Z-coordinate values specified according to the detection technical requirement file with the blade model; The theoretical measurement points on the scanning path corresponding to the same cross section are automatically generated by a special software.

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

5. The blade profile scanning method based on the measured profile normal correction of claim 1, wherein, The step S3 comprises the following steps: S 31 , before scanning measurement, align the blade measurement coordinate system to the theoretical model coordinate system; S 32 , the scanning is performed according to the improved scanning path in step S2; S 33 , the measured ball radius compensation function is closed during scanning, and the output measured coordinate result is the measured ball center coordinate.

6. The blade profile scanning method based on the measured profile normal correction of claim 1, wherein, 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, a radius value R is given, and the compensated point Pnt_v(x+R*i, y+R*j, z+R*k) is calculated. S 53 The measured coordinates of the center of the sphere are compensated for radius on each measuring section, and the measured point coordinates of the actual blade profile after compensation are output.

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