Online measurement and analysis method for five-axis numerical control machine tool

Abstract

The invention discloses an online measurement and analysis method for a five-axis numerical control machine tool, which comprises the following steps of: 1, modeling a kinematics theory and errors of a multi-body system, and determining four structural errors of the five-axis machine tool; 2, analyzing the errors of the four structures, and optimizing the verification errors of the measuring head of the machine tool; step 3; and error factors are removed, a related kinematic model is derived, and the error factors are substituted into the kinematic model for correction, so that error compensation of the five-axis machine tool is realized. The method has the beneficial effects that the error of the numerical control machine tool can be detected on line by establishing a multi-body system kinematics theory and an error model, manual detection is not needed, the measurement efficiency is improved, error reasons can be determined by analyzing four structural errors, a related kinematics model can be deduced, error compensation is obtained, and the error detection accuracy is improved. Therefore, the error factors are corrected and removed, and the on-line measurement precision of the countershaft numerical control machine tool is further improved.

Description

Technical Field

[0001] The present invention relates to the technical field of on-line measurement of five-axis numerical control machine tools. Specifically, it relates to a method for on-line measurement and analysis of five-axis numerical control machine tools. Background Technique

[0002] Five-axis linkage numerical control machine tools are machine tools with high technological content, high precision, and are specifically used for processing complex curved surfaces. Such machine tool systems have a crucial influence on industries such as a country's aviation, aerospace, military, scientific research, precision instruments, high-precision medical equipment, etc. The five-axis linkage numerical control machine tool system is a means to solve the processing of impellers, blades, marine propellers, heavy generator rotors, steam turbine rotors, large diesel engine crankshafts, etc.

[0003] To prevent large working errors in five-axis linkage numerical control machine tools, the existing five-axis linkage numerical control machine tools need to be manually detected before use, which is time-consuming and has low detection efficiency.

[0004] Regarding the problems in the related technology, no effective solution has been proposed yet. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for on-line measurement and analysis of five-axis numerical control machine tools to solve the problems proposed in the above background technique.

[0006] To achieve the above purpose, the present invention provides the following technical solution: A method for on-line measurement and analysis of five-axis numerical control machine tools includes the following steps: Step 1: Model the kinematics theory and error of the multi-body system to determine the four structural errors of the five-axis machine tool; Step 2: Analyze the four structural errors and optimize the error of the machine tool probe calibration; Step 3; Remove the error factors, derive the relevant kinematic model, and bring the error factors into the kinematic model for correction, so as to realize the error compensation of the five-axis machine tool.

[0007] Furthermore, the method for modeling the kinematics theory and error of the multi-body system is as follows: The first step: Determine the moving axes and coordinate systems of the machine tool; Combine the forward kinematics theory of the robot and the low-order body theory of the multi-body system to establish the forward motion topology structure of the tool of the five-axis numerical control machine tool; The second step: Based on the theory of differential motion relationship between coordinate systems, obtain the homogeneous transformation matrix between adjacent bodies of each moving part of the five-axis numerical control machine tool; The third step: According to the kinematics theory of the six degrees of freedom of a rigid body, analyze the geometric error terms of each axis of the five-axis numerical control machine tool, and determine the differential motion vectors of the geometric errors of the translational axis and the rotational axis.

[0008] Step 4: Combine the differential motion vectors of the geometric error terms of the above-mentioned motion axes and the homogeneous transformation matrices of each component in the tool coordinate system, and calculate the differential motion matrix of each moving component relative to the tool through MATLAB; Step 5: Multiply the differential motion vectors of the geometric error terms of each axis by the corresponding differential motion matrix to obtain the vector forms of the geometric error terms of each axis in the tool coordinate system. After superimposing these vectors, the kinematic theory and error model of the multi-body system in the tool coordinate system are obtained.

[0009] Furthermore, the kinematic theory of the six degrees of freedom of the rigid body includes translation along the X-axis, rotation around the X-axis, translation along the Y-axis, rotation around the Y-axis, translation along the Z-axis, and rotation around the Z-axis.

[0010] Furthermore, the method for analyzing the four structural errors of the five-axis machine tool is as follows; Establish the low-order body array of the five-axis CNC machine tool and derive the homogeneous characteristic matrix between adjacent bodies. Based on the homogeneous characteristic matrix, establish the motion error model of the five-axis CNC machine tool, and derive the actual position error equation and attitude deviation equation of the tool forming point.

[0011] Furthermore, the on-line measurement and analysis method for the five-axis CNC machine tool also includes the step of verifying the established error model.

[0012] Furthermore, the verification steps include the precision gauge block verification method, the standard ring gauge verification method, and the standard ball gauge verification method.

[0013] Furthermore, the specific steps of the precision gauge block verification method: Move the machine tool probe to both sides of the standard gauge block, sample points on the parallel side surfaces, and calculate the true value and error of the probe from the relative coordinate values between two points.

[0014] Furthermore, the specific steps of the standard ring gauge verification method: The ring gauge verification method uses a standard ring gauge fixed on the machine base, the probe moves, touches the inner ring or the outer ring, and samples points in a plane and calculates the coordinate values.

[0015] Furthermore, the specific steps of the standard ball gauge verification method: The azimuth where the probe touches the standard ball can be the entire spherical surface. The least squares evaluation method can be used to fit an enveloping spherical surface. Using the standard ball gauge to verify the probe, 5-point calibration or 9-point calibration can be performed on the standard ball.

[0016] Compared with the prior art, the present invention has the following beneficial effects: By establishing the kinematics theory and error model of the multi-body system, the error of the CNC machine tool can be detected online without manual detection, improving the measurement efficiency. By analyzing the four structural errors, the error causes can be clarified, the relevant kinematic models can be deduced, and the error compensation can be obtained, so as to correct the error factors and further improve the online measurement accuracy of the CNC machine tool for shafts. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0018] Figure 1 is the main flowchart of a five-axis CNC machine tool online measurement and analysis method according to an embodiment of the present invention; Figure 2 is the flowchart of the kinematics theory and error modeling method for the multi-body system in a five-axis CNC machine tool online measurement and analysis method according to an embodiment of the present invention; Figure 3 is the flowchart of the method for analyzing the four structural errors of a five-axis machine tool in a five-axis CNC machine tool online measurement and analysis method according to an embodiment of the present invention; Figure 4 is the flowchart of the verification of the kinematics theory and error model of the multi-body system in a five-axis CNC machine tool online measurement and analysis method according to an embodiment of the present invention; Figure 5 is the flowchart of the quasi-measurement verification method in a five-axis CNC machine tool online measurement and analysis method according to an embodiment of the present invention; Figure 6 is the flowchart of the standard ring gauge verification method in a five-axis CNC machine tool online measurement and analysis method according to an embodiment of the present invention; Figure 7 is the flowchart of the standard ball gauge verification method in a five-axis CNC machine tool online measurement and analysis method according to an embodiment of the present invention; Figure 8 is the flowchart of the six degrees of freedom of a rigid body in a five-axis CNC machine tool online measurement and analysis method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Next, in combination with the drawings and the specific embodiments, the invention will be further described: Embodiment

[0020] Please refer to Figure 1, A five-axis CNC machine tool on-line measurement and analysis method according to an embodiment of the present invention includes the following steps: Step 1: Model the kinematics theory and errors of the multi-body system to determine the four structural errors of the five-axis machine tool; Step 2: Analyze the four structural errors and optimize the errors in the machine tool probe calibration; Step 3: Remove the error factors, derive the relevant kinematic model, and substitute the error factors into the kinematic model for correction, so as to realize the error compensation of the five-axis machine tool.

[0021] In a further embodiment, the method for modeling the kinematics theory and errors of the multi-body system is as follows: The first step: Determine the motion axes and coordinate systems of the machine tool; combine the forward kinematics theory of the robot and the low-order body theory of the multi-body system to establish the forward motion topology structure of the tool of the five-axis CNC machine tool; The second step: Based on the differential motion relationship theory between coordinate systems, obtain the homogeneous transformation matrix between adjacent bodies of each moving part of the five-axis CNC machine tool; The third step: According to the six-degree-of-freedom kinematics theory of a rigid body, analyze the geometric error terms of each axis of the five-axis CNC machine tool, and determine the differential motion vectors of the geometric errors of the translation axis and the rotation axis.

[0022] The fourth step: Combine the differential motion vectors of the geometric error terms of each motion axis and the homogeneous transformation matrix of each part in the tool coordinate system, and calculate the differential motion matrix of each moving part relative to the tool through MATLAB; The fifth step: Multiply the differential motion vectors of the geometric error terms of each axis by the corresponding differential motion matrix to obtain the vector form of the geometric error terms of each axis in the tool coordinate system. After superimposing these vectors, the kinematics theory and error model of the multi-body system in the tool coordinate system are obtained.

[0023] In a further embodiment, the six-degree-of-freedom kinematics theory of the rigid body includes translation along the X axis, rotation about the X axis, translation along the Y axis, rotation about the Y axis, translation along the Z axis, and rotation about the Z axis In a further embodiment, the method for analyzing the four structural errors of the five-axis machine tool is as follows; An array of low-order bodies of a five-axis CNC machine tool is established, and the homogeneous characteristic matrix between adjacent bodies is derived. Based on the homogeneous characteristic matrix, a motion error model of the five-axis CNC machine tool is established, and the actual position error equation and attitude deviation equation of the tool forming point are derived. In a further embodiment, the on-line measurement and analysis method of the five-axis CNC machine tool further includes the step of verifying the established error model. The verification steps include the precision block verification method, the standard ring gauge verification method, and the standard ball gauge verification method. The specific steps of the precision block verification method are as follows: Move the machine tool probe to both sides of the standard block, sample points on the parallel side surfaces, and calculate the true value and error of the probe from the relative coordinate values between two points. The specific steps of the standard ring gauge verification method are as follows: The ring gauge verification method uses a standard ring gauge fixed on the machine base, the probe moves, touches the inner ring or the outer ring, takes points in a plane and calculates the coordinate values. The specific steps of the standard ball gauge verification method are as follows: The orientation where the probe touches the standard ball can be the entire spherical surface. The least squares evaluation method can be used to fit an enveloping spherical surface. Using the standard ball gauge to verify the probe, 5-point calibration or 9-point calibration can be performed on the standard ball.

[0024] Through the above solution of the present invention, by establishing the multi-body system kinematics theory and error model, the error of the CNC machine tool can be detected online without manual detection, improving the measurement efficiency. By analyzing the four structural errors, the error causes can be clarified, the relevant kinematic models can be derived, and the error compensation can be obtained, so as to correct the error factors and remove the error factors, further improving the online measurement accuracy of the CNC machine tool.

[0025] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An on-line measurement and analysis method for a five-axis numerical control machine tool, characterized in that It includes the following steps: Step 1: Conduct kinematic theory and error modeling for the multi-body system to determine the four structural errors of the five-axis machine tool; Step 2: Analyze the four structural errors and optimize the errors in the machine tool probe calibration; Step 3; Remove the error factors, derive the relevant kinematic model, and substitute the error factors into the kinematic model for correction, so as to achieve error compensation for the five-axis machine tool.

2. The on-line measurement and analysis method of a five-axis CNC machine tool according to claim 1, characterized in that The method for kinematic theory and error modeling of the multi-body system is as follows: The first step: Determine the motion axes and coordinate systems of the machine tool; combine the forward kinematic theory of the robot and the low-order body theory of the multi-body system to establish the forward motion topological structure of the tool of the five-axis CNC machine tool; The second step: Based on the differential motion relationship theory between coordinate systems, obtain the homogeneous transformation matrix between adjacent bodies of each moving part of the five-axis CNC machine tool; The third step: According to the kinematic theory of the six degrees of freedom of a rigid body, analyze the geometric error terms of each axis of the five-axis CNC machine tool, and determine the differential motion vectors of the geometric errors of the translational axis and the rotational axis.

3. The fourth step: Combine the differential motion vectors of the geometric error terms of each motion axis and the homogeneous transformation matrix of each component in the tool coordinate system, and calculate the differential motion matrix of each moving part relative to the tool through MATLAB; The fifth step: Multiply the differential motion vectors of the geometric error terms of each axis by the corresponding differential motion matrix to obtain the vector form of the geometric error terms of each axis in the tool coordinate system. After superimposing these vectors, the kinematic theory and error model of the multi-body system in the tool coordinate system are obtained.

4. A method for on-line measurement and analysis of a five-axis numerical control machine tool according to claim 2, characterized in that, The kinematic theory of the six degrees of freedom of the rigid body includes translation along the X axis, rotation around the X axis, translation along the Y axis, rotation around the Y axis, translation along the Z axis, and rotation around the Z axis.

5. A five-axis CNC machine tool on-line measurement and analysis method according to claim 1, characterized in that, The method for analyzing the four structural errors of the five-axis machine tool is as follows; Establish the low-order body array of the five-axis CNC machine tool and derive the homogeneous characteristic matrix between adjacent bodies. According to the homogeneous characteristic matrix, establish the motion error model of the five-axis CNC machine tool, and derive the actual position error equation and attitude deviation equation of the tool forming point.

6. The on-line measurement and analysis method of a five-axis numerical control machine tool according to claim 1, characterized in that, The online measurement and analysis method of the five-axis CNC machine tool also includes the step of verifying the established error model.

7. A five-axis CNC machine tool on-line measurement and analysis method according to claim 5, characterized in that The verification steps include the standard gauge verification method, the standard ring gauge verification method, and the standard ball gauge verification method.

8. A method for on-line measurement and analysis of a five-axis CNC machine tool according to claim 6, characterized in that, The specific steps of the standard gauge verification method: Move the machine tool probe to both sides of the standard gauge, take points and sample on the parallel side surfaces, and calculate the true value and error of the probe from the relative coordinate values between two points.

9. A method for on-line measurement and analysis of a five-axis numerical control machine tool according to claim 6, characterized in that The specific steps of the standard ring gauge verification method: The ring gauge verification method uses a standard ring gauge fixed on the machine base. The probe moves and touches the inner ring or the outer ring, takes points in a plane, and calculates the coordinate values.

10. A method for on-line measurement and analysis of a five-axis CNC machine tool according to claim 6, characterized in that, The specific steps of the standard ball gauge verification method: The orientation where the probe touches the standard ball can be the entire spherical surface. The least squares evaluation method can be used to fit an envelope spherical surface. Using the standard ball gauge to verify the probe, 5-point calibration or 9-point calibration can be performed on the standard ball.

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