Model-based compensation method for bending-torsion blade three-coordinate contact ball radius

Abstract

The application provides a model-based bending-twisting blade three-coordinate contact measurement ball radius compensation method, which comprises the following steps: S1, cloud generation on a blade profile theoretical point: using existing commercial software, according to a blade detection technical requirement document, generating different-height equal-section measurement theoretical points on a blade theoretical model; S2, coordinate system transformation on the blade theoretical model; S3, radius compensation amount calculation; S4, three-coordinate contact measurement ball radius compensation. The application can theoretically eliminate the radius compensation error of the three-coordinate spherical probe contact measurement of a large bending-sweep blade by using the equal-section method, can be directly used for three-coordinate measurement ball radius compensation in an actual measurement process, thereby reducing the inherent error of the measurement ball radius compensation in the current large bending-sweep blade measurement, and improving the profile measurement precision of the large bending-sweep blade.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aero-engine blade detection, and particularly relates to a model-based three-coordinate contact measurement ball radius compensation method for a curved and twisted blade. BACKGROUND

[0002] When a three-coordinate measuring machine adopts a contact type spherical probe to perform point measurement on a complex free-form surface, a cosine error is easily generated by using a theoretical point normal on a numerical model to replace a real point normal for radius compensation because the real point normal is unknown.

[0003] When the machining precision of an actual part is very high, the real point normal is very close to the theoretical point normal on the numerical model, and the cosine error can be ignored.

[0004] However, for some special parts, such as an aero-engine blade with a large bending and sweeping in the blade direction, even if the measured blade surface is exactly the same as the theoretical model (i.e., there is no machining error), a significant radius compensation error still exists when the radius compensation is performed according to the two-dimensional projection normal of the theoretical normal on the equal section.

[0005] When the bending and sweeping of the blade is large, the radius compensation error still exists when the radius compensation is performed according to the two-dimensional projection normal of the theoretical normal on the equal section.

[0006] To reduce the radius compensation error, the present application designs a model-based three-coordinate contact measurement ball radius compensation method for a curved and twisted blade to improve the precision of the three-coordinate contact spherical probe in measuring the large bending and sweeping blade profile by using the equal section method. SUMMARY

[0007] The present application aims to solve the problem of inaccurate three-coordinate ball radius compensation when the equal section method is used to measure a large bending and sweeping blade in the prior art, and provides a model-based three-coordinate contact measurement ball radius compensation method for a curved and twisted blade.

[0008] The present application solves the above technical problem by the following technical scheme:

[0009] A model-based three-coordinate contact measurement ball radius compensation method for a curved and twisted blade, characterized in that the compensation method comprises the following steps:

[0010] S1, cloud generation for a blade profile theoretical point: using an existing commercial software, equal section measurement theoretical points at different heights are generated on a blade theoretical model according to a blade detection technical requirement file;

[0011] S2, coordinate system transformation for the blade theoretical model;

[0012] S3, radius compensation amount calculation;

[0013] S4, three-coordinate contact ball radius compensation.

[0014] According to an embodiment of the present application, the theoretical model in step S1 is a design model of the blade, and the Z-axis of the design coordinate system points in parallel to the stacking axis of the blade and points from the blade root to the blade tip.

[0015] According to an embodiment of the present application, the different-height equal-sections in step S1 are formed by intersecting the blade model with planes with different Z-coordinate values according to the technical requirement file of the detection.

[0016] According to an embodiment of the present application, the theoretical points on the same equal-section in step S1 are automatically generated by the special software.

[0017] According to an embodiment of the present application, the special software is PCDMIS-BLADE software, and the PCDMIS-BLADE software generates a nom file.

[0018] According to an embodiment of the present application, the special software generates theoretical measurement points corresponding to different heights and corresponding normal vectors of each point.

[0019] According to an embodiment of the present application, step S2 comprises:

[0020] S 21 , taking an arbitrary section as ZO, and taking the set of blade-type theoretical points on the ZO section generated according to step S1 as an example, assuming that the starting point in the point set is point Pnt_o, projecting the theoretical normal vector V_Pnt0 of point Pnt_o onto the plane ZO, and recording the normal vector as Vp_Pnt0;

[0021] S 22 , taking Pnt0 as the origin, recorded as O_Pnt0; taking Vp_Pnt0 as the X-axis, recorded as X_Pnt0; taking the Z-axis of the initial design coordinate system of the blade as the Z-axis of the newly-built coordinate, recorded as Z_Pnt0; thus, a new coordinate system can be created, recorded as OXYZ_Pnt0;

[0022] S 23 , performing coordinate system transformation on the blade theoretical model, from the original design coordinate system OXYZ to the coordinate system OXYZ_Pnt0.

[0023] According to an embodiment of the present application, step S3 comprises:

[0024] S 31 , setting the contact range of the three-coordinate spherical probe on the surface of the blade, taking Z_Pnt0 as the center of the sphere, and taking the radius r of the three-coordinate spherical probe as the radius, generating a space sphere, and taking the curved surface of the blade model surrounded by the space sphere as the alternative area of the contact of the measurement ball, recorded as Area_Sr.

[0025] S 32 , under the coordinate system OXYZ_Pnt0, searching a point X_Pnt on the X_Pnt0 axis within the range of [r, 2r] so that the closest distance between X_Pnt and the surface of Area_Sr is r, and recording the coordinate value of X_Pnt on the X_Pnt0 axis at this time, which is the radius compensation amount of the point Pnt_o, denoted as R.

[0026] According to one embodiment of the present application, the step S4 comprises:

[0027] S 41 , after the blade profile measurement is completed, the measured spherical center coordinates Sp_O(x, y, z) corresponding to the theoretical measurement point Pnt_o are obtained, and the point Sp_O is projected to the ZO plane, and the projection point is denoted as Sp_Op(x, y, ZO);

[0028] S 42 , the point Sp_Op is moved by r_m in the direction opposite to the normal vector Vp_Pnt0 on the ZO plane to obtain a point m_Pnt0(x_m, y_m, ZO), and the point m_Pnt0 is the blade profile measured point after the final spherical radius compensation.

[0029] According to one embodiment of the present application, the step S4 further comprises:

[0030] S 43 , if the steps S 41 and S 42 are not used for compensation, other self-defined measurement section projection two-dimensional compensation methods are used, only the initial radius compensation amount is modified from r to R, and then R is substituted into the defined compensation method to complete the coordinate calculation of the blade profile measured point.

[0031] The positive progress effect of the present application is that:

[0032] The model-based bending-twisted blade three-coordinate contact measurement spherical radius compensation method can theoretically eliminate the radius compensation error of the equal-section method three-coordinate spherical probe contact measurement of large-camber-swept blades, can be directly used for three-coordinate spherical radius compensation in actual measurement process, thereby reducing the inherent error of the spherical radius compensation in the current large-camber-swept blade measurement, and improving the profile measurement accuracy of the large-camber-swept blade. BRIEF DESCRIPTION OF DRAWINGS

[0033] The above and other features, properties, and advantages of the present application will become more apparent through the following description with reference to the accompanying drawings and embodiments, in which the same reference numerals are used throughout to represent the same features, and wherein:

[0034] Figure 1 It is a large bending-twisted blade and profile measurement schematic diagram.

[0035] Figure 2 Fig. 1 is a schematic diagram of a ball radius compensation value R in a model-based bending-twisting blade three-coordinate contact ball radius compensation method of the present application.

[0036] Figure 3 Fig. 2 is a flowchart of an implementation of the model-based bending-twisting blade three-coordinate contact ball radius compensation method of the present application.

[0037] Figure 4 Fig. 3 is a schematic diagram of a blade profile discrete point and a point normal vector in the model-based bending-twisting blade three-coordinate contact ball radius compensation method of the present application.

[0038] Figure 5 Fig. 4 is a schematic diagram of a shortest distance search calculation process in the model-based bending-twisting blade three-coordinate contact ball radius compensation method of the present application. DETAILED DESCRIPTION

[0039] 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 with reference to the accompanying drawings.

[0040] Reference will now be made in detail to the 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.

[0041] Further, although the terms used in the present application are selected from publicly-known terms, some of the terms mentioned in the specification of the present application can be selected by the applicant in his or her judgment, and the detailed meanings thereof are described in the relevant part of the description herein.

[0042] Further, the present application is to be understood not only by the actual terms used but also by the meanings of each term implied therein.

[0043] As Figures 1 to 5 shown, the present application discloses a model-based bending-twisting blade three-coordinate contact ball radius compensation method, which comprises the following steps:

[0044] Step S1: cloud generation for blade profile theoretical points: using existing commercial software, according to the blade detection technical requirement file, generating different height equal-section measurement theoretical points on the blade theoretical model.

[0045] Preferably, the theoretical model in the step S1 is a design model of the blade, and the design coordinate system Z axis points in parallel to the blade stacking axis and points from the blade root to the blade tip.

[0046] Further, the different height equal sections in the step S1 are planes with different Z coordinate values specified according to the detection technical requirement file, which are intersected with the blade model to form.

[0047] The theoretical points on the same equal section in the step S1 are automatically generated by a special software. The special software is PCDMIS-BLADE software, and the PCDMIS-BLADE software generates a nom file.

[0048] The special software generates the theoretical measurement points corresponding to different heights and the corresponding normal vectors of each point.

[0049] Step S2, coordinate system transformation is performed on the blade theoretical model.

[0050] Preferably, the step S2 includes:

[0051] Step S 21 , taking an arbitrary section as ZO, taking the blade theoretical point set on the ZO section generated according to the step S1 as an example, assuming that the starting point in the point set is point Pnt_o, projecting the theoretical normal vector V_Pnt0 of the point Pnt_o onto the plane ZO, and recording it as the normal vector Vp_Pnt0;

[0052]

[0053] Step S 22 , taking Pnt0 as the origin, recording it as O_Pnt0; taking Vp_Pnt0 as the X axis, recording it as X_Pnt0; taking the Z axis of the initial design coordinate system of the blade as the Z axis of the newly created coordinate, recording it as Z_Pnt0; thus, a new coordinate system can be created, recording it as OXYZ_Pnt0;

[0054] Step S 23 , coordinate system transformation is performed on the blade theoretical model, from the original design coordinate system OXYZ to the coordinate system OXYZ_Pnt0.

[0055] Step S3, radius compensation amount calculation.

[0056] Preferably, the step S3 includes:

[0057] Step S 31 , setting the touch range of the three-coordinate spherical probe on the surface of the blade, taking Z_Pnt0 as the center of the sphere, and taking the radius r of the three-coordinate spherical probe as the radius to generate a space sphere, and the curved surface of the blade model surrounded by the space sphere is taken as the alternative area of the measurement ball contact, recording it as Area_Sr.

[0058] Step S 32 ​, search a point X_Pnt on the X_Pnt0 axis in the range of [r, 2r] under the coordinate system OXYZ_Pnt0, so that the distance between X_Pnt and the surface of Area_Sr is r, record the coordinate value of X_Pnt on the X_Pnt0 axis at this time, which is the radius compensation of the point Pnt_o, denoted as R.

[0059] Step S4, three-coordinate contact ball radius compensation.

[0060] Preferably, the step S4 comprises:

[0061] Step S 41 After the blade profile measurement is completed, the measured ball center coordinates Sp_O(x, y, z) corresponding to the theoretical measurement point Pnt_o are obtained, and the point Sp_O is projected to the ZO plane, and the projection point is denoted as Sp_Op(x, y, ZO);

[0062] Step S 42 The point Sp_Op is moved by r_m in the direction opposite to the normal vector Vp_Pnt0 on the ZO plane to obtain a point m_Pnt0(x_m, y_m, ZO), and the point m_Pnt0 is the blade profile measured point after the final ball radius compensation.

[0063] Further, the step S4 further comprises:

[0064] Step S 43 If the steps S 41 and S 42 are not used, the method is compensated, and other self-defined measurement section projection two-dimensional compensation methods are used, only the initial radius compensation amount is modified from r to R, and then R is substituted into the defined compensation method to complete the coordinate calculation of the blade profile measured point.

[0065] The model-based bending-twisting blade three-coordinate contact ball radius compensation method has the following improvements:

[0066] I. Through theoretical model analysis, a radius compensation error model of the equal-section method three-coordinate spherical needle contact measurement of a large bending-sweep blade is established.

[0067] II. Under the constraint of the equal-section method measurement condition, the three-coordinate spherical measuring needle correction radius compensation amount is calculated by using the theoretical model of the blade.

[0068] III. The correction radius compensation amount obtained by the theoretical calculation is used to replace the spherical measuring needle radius for actual measurement radius compensation, and the accuracy of the radius compensation is improved.

[0069] In summary, the model-based bending-torsion blade three-coordinate contact ball radius compensation method can eliminate the radius compensation error of the three-coordinate spherical probe contact measurement of the large bending-sweep blade in theory, can be directly used for three-coordinate ball radius compensation in the actual measurement process, thereby reducing the inherent error of the ball radius compensation in the current large bending-sweep blade measurement, and improving the blade profile measurement accuracy of the large bending-sweep blade.

[0070] The above-described disclosure is merely exemplary in nature and is not intended to limit the present application. Although the present application has been described in considerable detail with reference to certain exemplary embodiments thereof, various modifications, improvements and alterations will occur to those skilled in the art upon reading the foregoing description. Such modifications, improvements and alterations are intended to be within the spirit and scope of the exemplary embodiments of the present application. Therefore, it is intended that the exemplary embodiments of the present application be construed as including all such modifications, improvements and alterations.

[0071] Also, the present application uses certain terminology in describing the embodiments of the present application. As used herein, the terms "one embodiment," "an embodiment," "some embodiments," or "one alternative" are intended to mean that a certain feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Therefore, it is emphasized and should be appreciated that a varied "embodiment" or "one alternative" described in various places of this specification can not be to refer to the same embodiment. In addition, certain features, structures, or characteristics of one or more embodiments of the present application can be suitably combined in a single embodiment.

[0072] Although the specific embodiments of the present application have been described above, those skilled in the art will understand that these are merely exemplary, and the scope of protection 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 such changes and modifications fall within the scope of protection of the present application.

Claims

1. A model-based bend-twist-blade three-coordinate contact measurement ball radius compensation method, characterized in that, The compensation method comprises the following steps: S1, cloud generation is performed on a theoretical point of a blade profile: a special software is used to generate theoretical points of equal sections at different heights on a theoretical model of a blade according to a blade detection technical requirement document; The special software is PCDMIS-BLADE software, and the PCDMIS-BLADE software generates a nom file; S2, coordinate system transformation is performed on the theoretical model of the blade; The step S2 comprises: S 21 In step S1, the point set of the airfoil theory is generated. In step S2, the point set of the airfoil theory is projected onto the plane ZO. In step S3, the point set of the airfoil theory is projected onto the plane ZO. In step S4, the point set of the airfoil theory is projected onto the plane ZO. In step S5, the point set of the airfoil theory is projected onto the plane ZO. In step S6, the point set of the airfoil theory is projected onto the plane ZO. In step S7, the point set of the airfoil theory is projected onto the plane ZO. In step S8, the point set of the airfoil theory is projected onto the plane ZO. In step S9, the point set of the airfoil S 22 , take Pnt0 as the origin, record as O_Pnt0; take Vp_Pnt0 as the X axis, record as X_Pnt0; take the Z axis of the initial design coordinate system of the blade as the Z axis of the newly created coordinate, record as Z_Pnt0; thus a new coordinate system can be created, record as OXYZ_Pnt0; S 23 , coordinate system transformation is performed on the blade theoretical model, from the original design coordinate system OXYZ to the coordinate system OXYZ_Pnt0. S3, radius compensation amount calculation; The step S3 comprises: S 31 , set the touch range of the three-coordinate spherical probe on the surface of the blade, take Z_Pnt0 as the center of the sphere and the three-coordinate spherical probe radius r as the radius to generate a space sphere, and the curved surface of the blade model surrounded by the space sphere is taken as the alternative area of the probe ball contact, denoted as Area_Sr; S 32 , under the coordinate system OXYZ_Pnt0, searching a point X_Pnt on the X_Pnt0 axis in the range of [r, 2r] such that the closest distance between X_Pnt and the surface of Area_Sr is r, recording the coordinate value of X_Pnt on the X_Pnt0 axis at this time, which is the radius compensation amount of the point Pnt_o, denoted as R; S4, three-coordinate contact measurement ball radius compensation; The step S4 comprises: S 41 After the blade profile measurement is completed, the measured spherical center coordinates Sp_O(x, y, z) corresponding to the theoretical measurement point Pnt_o are obtained, and the point Sp_O is projected to the ZO plane, and the projection point is denoted as Sp_Op(x, y, ZO). S 42 , moving the point Sp Op on the ZO plane along the direction opposite to the normal vector Vp Pnt0 by r_m, obtaining a point m_Pnt0(x_m, y_m, ZO), the point m_Pnt0 being the measured point of the blade profile after the final compensation of the measured ball radius.

2. The model-based bend-twist vane three-coordinate contact measurement ball radius compensation method of claim 1, wherein, In the step S1, the theoretical model is a design model of the blade, a design coordinate system of which has a Z-axis pointing in parallel to a stacking axis of the blade and pointing from a blade root to a blade tip.

3. The model-based bend-twist vane three-coordinate contact measurement ball radius compensation method of claim 1, wherein, In the step S1, different-height equal sections are planes intersecting with the blade model according to different Z-coordinate values specified in the detection technical requirement document.

4. The model-based bend-twist vane three-coordinate contact measurement ball radius compensation method of claim 1, wherein, The special software generates theoretical measurement points corresponding to different heights and corresponding normal vectors of each point.

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