Model-based curved-twisted blade three-coordinate contact measurement ball radius compensation method

Abstract

The invention provides a model-based curved and twisted blade three-coordinate contact measurement sphere radius compensation method, which comprises the following steps of S1, performing cloud generation on blade profile theoretical points: generating uniform-section measurement theoretical points with different heights on a blade theoretical model by utilizing existing commercial software according to a blade detection technical requirement file; s2, performing coordinate system transformation on the blade theoretical model; s3, calculating the radius compensation amount; and S4, compensating the radius of the three-coordinate probe. The method provided by the invention can theoretically eliminate the radius compensation error of the large-swept-curve blade measured by the three-coordinate spherical probe in a contact manner in a uniform-section method, and can be directly used for three-coordinate measuring sphere radius compensation in an actual measurement process, so that the inherent error of measuring sphere radius compensation during the measurement of the current large-swept-curve blade is reduced; and the blade profile measurement precision of the large-curved-swept blade is improved.

Description

Technical Field

[0001] The invention relates to the technical field of aero-engine blade detection, and in particular to a three-coordinate contact measuring ball radius compensation method for a bending and twisting blade based on a model. Background Art

[0002] The three-dimensional coordinate measuring machine uses a contact spherical stylus to measure points on complex free-form surfaces. Because the normal line of the actual measured point is unknown, the normal line of the theoretical point on the digital model is used instead for radius compensation, which is prone to cosine error.

[0003] When the actual parts processing accuracy is very high and the normal line of the measured point is very close to the normal line of the theoretical point on the digital model, this cosine error can usually be ignored.

[0004] However, for some special parts, such as aircraft engine blades with large sweep in the blade body direction, the current existing three-dimensional coordinate measurement using a contact spherical probe according to the equal section method will result in a large number of errors, even if the measured blade profile is exactly the same as the theoretical model (i.e. there is no processing error).

[0005] In places where the blade is bent and swept more, there will still be obvious radius compensation errors when the measuring ball radius compensation is performed according to the two-dimensional projection normal of the theoretical normal on the equal cross section.

[0006] In order to reduce the radius compensation error, the present invention designs a model-based three-coordinate contact ball radius compensation method for bending and twisting blades to improve the accuracy of measuring the blade profile of large curved and swept blades using a three-coordinate contact spherical probe using the equal-section method. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defect of inaccurate three-coordinate measuring ball radius compensation when measuring large swept blades by the equal-section method in the prior art, and to provide a model-based three-coordinate contact measuring ball radius compensation method for bent and torsion blades.

[0008] The present invention solves the above technical problems through the following technical solutions:

[0009] A model-based three-coordinate contact ball radius compensation method for bending and twisting blades, characterized in that the compensation method comprises the following steps:

[0010] S 1 1. Generate cloud of blade profile theoretical points: Use existing commercial software to generate equal cross-section measurement theoretical points of different heights on the blade theoretical model according to the blade detection technical requirements document;

[0011] S 2 , transform the coordinate system of the blade theoretical model;

[0012] S 3 , radius compensation calculation;

[0013] S 4 , three-coordinate probe radius compensation.

[0014] According to one embodiment of the present invention, the step S 1 The theoretical model described in the figure is a design model of the blade, and the Z-axis of its design coordinate system is parallel to the blade stacking axis and points from the blade root to the blade tip.

[0015] According to one embodiment of the present invention, the step S 1 The equal sections at different heights are formed by the intersection of planes with different Z coordinate values ​​specified in the detection technical requirements file and the blade model.

[0016] According to one embodiment of the present invention, the step S 1 The theoretical points on the same cross section are automatically generated by special software.

[0017] According to one embodiment of the present invention, the dedicated software is PCDMIS-BLADE software, and the PCDMIS-BLADE software generates a nom file.

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

[0019] According to one embodiment of the present invention, the step S 2 include:

[0020] S 21 , take any section as ZO, take the blade profile theoretical point set generated according to step S1 on the ZO section as an example, assume that the starting point in the point set is point Pnt_o, project the theoretical normal vector V_Pnt0 of point Pnt_o onto plane ZO, and record it as normal vector Vp_Pnt0;

[0021] S 22 , take Pnt0 as the origin, recorded as O_Pnt0; take Vp_Pnt0 as the X-axis, recorded 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, recorded as Z_Pnt0; thus, a new coordinate system can be created, recorded as OXYZ_Pnt0;

[0022] S 23 , transform the coordinate system of the blade theoretical model from the original design coordinate system OXYZ to the coordinate system OXYZ_Pnt0.

[0023] According to one embodiment of the present invention, the step S 3 include:

[0024] S 31, set the touch range of the three-coordinate spherical probe on the blade surface, take Z_Pnt0 as the sphere center and the radius r of the three-coordinate spherical probe as the radius, generate a space sphere, and the blade model surface surrounded by the space sphere is used as the candidate area for the probe sphere to contact, recorded as Area_Sr;

[0025] S 32 , in the coordinate system OXYZ_Pnt0, search for a point X_Pnt in the range of [r, 2r] on the X_Pnt0 axis, so that the closest distance between X_Pnt and the surface of Area_Sr is r, and record the coordinate value of X_Pnt on the X_Pnt0 axis at this time. The coordinate value is the radius compensation amount of point Pnt_o, recorded as R.

[0026] According to one embodiment of the present invention, the step S 4 include:

[0027] S 41 After the blade profile measurement is completed, the measured sphere center coordinates Sp_O (x, y, z) corresponding to the theoretical measurement point Pnt_o will be obtained, and the point Sp_O will be projected onto the ZO plane, and the projection point is recorded as Sp_Op (x, y, ZO);

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

[0029] According to one embodiment of the present invention, the step S 4 Also included:

[0030] S 43 If step S is not adopted 41 and step S 42 The method is used for compensation, while other customized measurement section projection two-dimensional compensation methods are used. It is only necessary to correct the initial radius compensation amount from r to R, and then substitute R into the defined compensation method to complete the coordinate calculation of the actual measured point of the blade profile.

[0031] The positive and progressive effects of the present invention are:

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

[0033] 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:

[0034] Figure 1 Schematic diagram of large twist blade and blade profile measurement.

[0035] Figure 2 It is a schematic diagram of the measuring ball radius compensation value R in the three-coordinate contact measuring ball radius compensation method for bending and twisting blades based on the model of the present invention.

[0036] Figure 3 The present invention is a flow chart for implementing the model-based three-coordinate contact ball radius compensation method for bending and twisting blades.

[0037] Figure 4 It is a schematic diagram of the blade profile discrete points and the normal vectors of each point in the three-coordinate contact measurement sphere radius compensation method of the bending and twisting blade based on the model of the present invention.

[0038] Figure 5 The diagram is a schematic diagram of the shortest distance search calculation process in the three-coordinate contact measuring sphere radius compensation method for bending and twisting blades based on the model of the present invention. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] like Figures 1 to 5 As shown, the present invention discloses a model-based three-coordinate contact ball radius compensation method for bending and twisting blades, which includes the following steps:

[0044] Step S 12. Generate cloud of blade profile theoretical points: Use existing commercial software to generate equal-section measurement theoretical points of different heights on the blade theoretical model in accordance with the blade detection technical requirements document.

[0045] Preferably, the step S 1 The theoretical model described in the figure is a design model of the blade, and the Z-axis of its design coordinate system is parallel to the blade stacking axis and points from the blade root to the blade tip.

[0046] Furthermore, the step S 1 The equal sections at different heights are formed by the intersection of planes with different Z coordinate values ​​specified in the detection technical requirements file and the blade model.

[0047] The step S 1 The theoretical points on the same cross section are automatically generated by special software. The special software is PCDMIS-BLADE software, and the PCDMIS-BLADE software generates a nom file.

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

[0049] Step S 2 , transform the coordinate system of the blade theoretical model.

[0050] Preferably, the step S 2 include:

[0051] Step S 21 , take any section as ZO, take the blade profile theoretical point set generated according to step S1 on the ZO section as an example, assume that the starting point in the point set is point Pnt_o, project the theoretical normal vector V_Pnt0 of point Pnt_o onto plane ZO, and record it as normal vector Vp_Pnt0;

[0052] Step S 22 , take Pnt0 as the origin, recorded as O_Pnt0; take Vp_Pnt0 as the X-axis, recorded 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, recorded as Z_Pnt0; thus, a new coordinate system can be created, recorded as OXYZ_Pnt0;

[0053] Step S 23 , transform the coordinate system of the blade theoretical model from the original design coordinate system OXYZ to the coordinate system OXYZ_Pnt0.

[0054] Step S 3 , calculation of radius compensation.

[0055] Preferably, the step S 3 include:

[0056] Step S 31 , set the touch range of the three-coordinate spherical probe on the blade surface, take Z_Pnt0 as the sphere center and the radius r of the three-coordinate spherical probe as the radius, generate a space sphere, and the blade model surface surrounded by the space sphere is used as the candidate area for the probe sphere to contact, recorded as Area_Sr;

[0057] Step S 32 , in the coordinate system OXYZ_Pnt0, search for a point X_Pnt in the range of [r, 2r] on the X_Pnt0 axis, so that the closest distance between X_Pnt and the surface of Area_Sr is r, and record the coordinate value of X_Pnt on the X_Pnt0 axis at this time. The coordinate value is the radius compensation amount of point Pnt_o, recorded as R.

[0058] Step S 4 , three-coordinate probe radius compensation.

[0059] Preferably, the step S 4 include:

[0060] Step S 41 After the blade profile measurement is completed, the measured sphere center coordinates Sp_O (x, y, z) corresponding to the theoretical measurement point Pnt_o will be obtained, and the point Sp_O will be projected onto the ZO plane, and the projection point is recorded as Sp_Op (x, y, ZO);

[0061] Step S 42 , on the ZO plane, move the point Sp_Op by r_m in the direction opposite to the normal vector Vp_Pnt0 to obtain a point m_Pnt0 (x_m, y_m, ZO). The point m_Pnt0 is the actual measured point of the blade profile after the final measuring sphere radius compensation.

[0062] Furthermore, the step S 4 Also included:

[0063] Step S 43 If step S is not adopted 41 and step S 42 The method is used for compensation, while other customized measurement section projection two-dimensional compensation methods are used. It is only necessary to correct the initial radius compensation amount from r to R, and then substitute R into the defined compensation method to complete the coordinate calculation of the actual measured point of the blade profile.

[0064] The model-based three-coordinate contact ball radius compensation method for bending and twisting blades of the present invention has the following improvements:

[0065] First, through theoretical model analysis, a radius compensation error model for three-coordinate spherical needle contact measurement of large swept blades using the equal-section method was established.

[0066] 2. Using the theoretical model of the blade, the radius compensation of the three-coordinate spherical probe is calculated under the constraints of the equal-section method.

[0067] Third, the corrected radius compensation amount obtained by the theoretical calculation is used instead of the spherical probe radius to perform actual measurement radius compensation, thereby improving the accuracy of radius compensation.

[0068] To sum up, the model-based three-coordinate contact sphere radius compensation method for bent and twisted blades of the present invention can theoretically eliminate the radius compensation error of the equal-section method three-coordinate spherical probe contact measurement of large swept blades, and can be directly used for three-coordinate sphere radius compensation in the actual measurement process, thereby reducing the inherent error of the sphere radius compensation in the current measurement of large swept blades and improving the blade profile measurement accuracy of large swept blades.

[0069] For those skilled in the art, the above invention disclosure is only used as an example and does not constitute a limitation of the present application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements and amendments to the present application. Such modifications, improvements and amendments are suggested in the present application, so such modifications, improvements and amendments still belong to the spirit and scope of the exemplary implementation of the present application.

[0070] At the same time, the present application uses specific words to describe the embodiments of the present application. For example, "one embodiment", "an embodiment", and / or "some embodiments" refer to a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that "one embodiment" or "an embodiment" or "an alternative embodiment" mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.

[0071] 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 model-based three-coordinate contact ball radius compensation method for bending and twisting blades, characterized in that: The compensation method comprises the following steps: S1. Generate cloud of blade profile theoretical points: Generate equal cross-section measurement theoretical points of different heights on the blade theoretical model using existing commercial software according to the blade detection technical requirements document; S2, transforming the coordinate system of the blade theoretical model; S3, radius compensation calculation; S4, three-coordinate measuring probe radius compensation.

2. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 1 is characterized in that: The theoretical model in step S1 is a design model of the blade, and the Z axis of its design coordinate system is parallel to the blade stacking axis and points from the blade root to the blade tip.

3. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 1 is characterized in that: In step S1, the equal cross sections at different heights are formed by the intersection of planes with different Z coordinate values ​​specified in the inspection technical requirement file and the blade model.

4. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 3 is characterized in that: The theoretical points on the same cross section in step S1 are automatically generated by dedicated software.

5. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 4 is characterized in that: The dedicated software is PCDMIS-BLADE software, and the PCDMIS-BLADE software generates a nom file.

6. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 5 is characterized in that: The dedicated software generates theoretical measurement points corresponding to different heights and the corresponding normal vectors of each point.

7. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 1 is characterized in that: The step S2 comprises: S 21 , take any section as ZO, take the blade profile theoretical point set generated according to step S1 on the ZO section as an example, assume that the starting point in the point set is point Pnt_o, project the theoretical normal vector V_Pnt0 of point Pnt_o onto plane ZO, and record it as normal vector Vp_Pnt0; S 22 , take Pnt0 as the origin, recorded as O_Pnt0; take Vp_Pnt0 as the X-axis, recorded 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, recorded as Z_Pnt0; thus, a new coordinate system can be created, recorded as OXYZ_Pnt0; S 23 , transform the coordinate system of the blade theoretical model from the original design coordinate system OXYZ to the coordinate system OXYZ_Pnt0.

8. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 1 is characterized in that: The step S3 comprises: S 31 , set the touch range of the three-coordinate spherical probe on the blade surface, take Z_Pnt0 as the sphere center and the radius r of the three-coordinate spherical probe as the radius, generate a space sphere, and the blade model surface surrounded by the space sphere is used as the candidate area for the probe sphere to contact, recorded as Area_Sr; S 32 , in the coordinate system OXYZ_Pnt0, search for a point X_Pnt in the range of [r, 2r] on the X_Pnt0 axis, so that the closest distance between X_Pnt and the surface of Area_Sr is r, and record the coordinate value of X_Pnt on the X_Pnt0 axis at this time. The coordinate value is the radius compensation amount of point Pnt_o, recorded as R.

9. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 1, characterized in that: The step S4 comprises: S 41 After the blade profile measurement is completed, the measured sphere center coordinates Sp_O (x, y, z) corresponding to the theoretical measurement point Pnt_o will be obtained, and the point Sp_O will be projected onto the ZO plane, and the projection point is recorded as Sp_Op (x, y, ZO); S 42 , on the ZO plane, move the point Sp_Op by r_m in the direction opposite to the normal vector Vp_Pnt0 to obtain a point m_Pnt0 (x_m, y_m, ZO). The point m_Pnt0 is the actual measured point of the blade profile after the final measuring sphere radius compensation.

10. The model-based three-coordinate contact ball radius compensation method for bending and twisting blades according to claim 9, characterized in that: The step S4 also includes: S 43 If step S is not adopted 41 and step S 42 The method is used for compensation, while other customized measurement section projection two-dimensional compensation methods are used. It is only necessary to correct the initial radius compensation amount from r to R, and then substitute R into the defined compensation method to complete the coordinate calculation of the actual measured point of the blade profile.

Images