A method for characterizing the dynamic characteristics of CNC machine tools based on tracing the sources of geometric errors in machined parts.

Abstract

This invention discloses a method for characterizing the dynamic characteristics of CNC machine tools based on tracing the geometric errors of machined parts. This method can guide machine tool designers in optimizing the design of relevant components. The technical solution of this invention involves detecting the normal deviation of side-milled parts and then using mathematical methods to calculate the mutual moment of error between the theoretical and actual tangential contact lines during workpiece machining. For parts machined in a single-layer side-milling process, there exists a theoretical tangential contact line, i.e., the straight generatrix of that section, in any cutting section. Points are placed on the straight generatrix and its actual three-dimensional coordinates are measured. In three-dimensional space, the theoretical and actual tangential contact lines are fitted based on the theoretical and actual measurement points, respectively. The mutual moment of error between the two spatial lines can be calculated using mathematical methods. This invention solves the problem of the difficulty in characterizing the dynamic characteristics of CNC machine tools and has guiding significance for machine tool design.

Description

Technical Field

[0001] This invention relates to the field of machine tool equipment, and more specifically to a method for characterizing the dynamic characteristics of CNC machine tools based on tracing the source of geometric errors in machined parts. Background Technology

[0002] With the rapid development of the manufacturing industry, the improvement of part geometric accuracy is increasingly constrained by the dynamic characteristics of CNC machine tools. However, the dynamic characteristics of CNC machine tools are affected by a variety of factors, making it difficult to form a unified index to characterize them. This leads to difficulties in evaluating and comparing the performance of different CNC machine tools. The dynamic characteristics of CNC machine tools are influenced by various factors, such as the machine tool topology, the stiffness and stiffness distribution of key components, changes in the feed speed of each axis during machining, and the phase difference of each axis feed system. The diversity and complexity of these factors make accurately evaluating the dynamic characteristics of machine tools a technical challenge. Existing methods for evaluating the dynamic characteristics of CNC machine tools are often based on theoretical models, which may not fully reflect the performance of CNC machine tools under actual machining conditions. The difference between the theoretical model and the actual machining state may lead to deviations between the evaluation results and actual performance. In the continuous development of CNC machine tools, accurately evaluating and characterizing their dynamic characteristics is particularly important because it directly affects the geometric accuracy of parts. Existing technologies have limitations in evaluating the dynamic characteristics of CNC machine tools, such as the difficulty in tracing the source of errors. Furthermore, existing methods for evaluating the dynamic characteristics of CNC machine tools cannot fully and objectively reflect the actual working state of the machine tool in the production environment. An objective and accurate assessment of the machine tool's performance during actual machining is crucial for improving manufacturing accuracy and production efficiency. Therefore, in the evaluation of the dynamic characteristics of CNC machine tools, there is currently a lack of a single and intuitive technical indicator to represent the dynamic characteristics of machine tools. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing technologies by characterizing the dynamic characteristics of CNC machine tools based on the geometric error characteristics of machined parts. This provides a new index for evaluating the comprehensive dynamic characteristics of CNC machine tools and a new approach for tracing the source of machine tool errors. This invention provides a method for characterizing the dynamic characteristics of CNC machine tools based on tracing the source of geometric errors in machined parts. The calculation of the dynamic characteristics of CNC machine tools based on test piece cutting can more objectively and realistically assess the actual working state of the CNC machine tool. Since in side milling, the ideal tool contact line coincides with the straight generatrix of the part, the geometric error of the part can be represented by points on the ideal contact line and actual measured points. Furthermore, by fitting the points on the ideal contact line and the actual measured points of the part, two spatial straight lines can be obtained. By calculating the error cross moments of the two straight lines, the spatial positional relationship between the two straight lines at this cross-section can be obtained, thus characterizing the dynamic characteristics of the machine tool at this time.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A method for characterizing the dynamic characteristics of CNC machine tools based on tracing the source of geometric errors in machined parts, used to characterize the dynamic characteristics of CNC machine tools, includes:

[0006] 1) Perform isoparametric point layout on the machined parts, with a point count of m×n, where m is the number of measurement points in the u direction and n is the number of measurement points in the v direction; perform coordinate measuring machine (CMM) inspection to obtain the theoretical point cloud P of the measurement points. T And the actual 3D coordinate point cloud P M ;

[0007] 2) in u i In the cross section, based on the spiral theory, a spatial linear fit is performed on the theoretical and actual measurement points in the v-direction, and the Plücker coordinates of the two lines are calculated to obtain the theoretical tangent line in the cross section. and the actual tangent line

[0008] 3) Calculate the mutual moments of the errors between the two lines:

[0009] Furthermore, the error cross-moment originates from the geometric error distribution pattern of the parts processed by the machine tool.

[0010] Furthermore, the actual measuring points of the machined parts are approximately linearly distributed in the v direction of the u-section of the machined parts.

[0011] Furthermore, the actual three-dimensional coordinate point cloud of the processed part can be linearly fitted into an actual tangent line in space.

[0012] Furthermore, the Plücker coordinates of the actual tangential line can be solved based on the spiral theory.

[0013] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the program to implement the steps of the CNC machine tool dynamic characteristic characterization method.

[0014] A computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of the CNC machine tool dynamic characteristic characterization method.

[0015] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0016] 1. This invention reflects the dynamic characteristics of machine tools from the perspective of the error distribution law of processed parts. It can provide a basis for machine tool manufacturers to improve their designs and provide machine tool users with actual parameter performance of the machine tool.

[0017] 2. Provides more accurate dynamic characteristic evaluation: By using a test piece-based cutting method, this invention can more accurately evaluate the dynamic characteristics of CNC machine tools, especially their performance in side milling.

[0018] 3. Addressing the shortcomings of existing technologies: To address the lack of unified dynamic characteristic evaluation indicators in existing technologies, a new evaluation method is proposed, which enhances the universality and comparability of the evaluation results.

[0019] 4. Improved measurement effect in terms of geometric accuracy: By comparing the ideal tangent line with the actual measuring point, the present invention can more accurately characterize the geometric error of the part, thereby improving the geometric accuracy of the machined part.

[0020] 5. Better integration of theory and actual working conditions: This invention bridges the gap between theoretical models and actual machining conditions by using actual cutting of test pieces, ensuring that the evaluation results are closer to actual production conditions.

[0021] 6. Improve the machining efficiency and quality of CNC machine tools: Through more accurate dynamic characteristic evaluation, this invention helps to optimize the operating parameters and machining strategies of CNC machine tools, thereby improving machining efficiency and the quality of produced parts.

[0022] 7. Promote technological progress in manufacturing: The application of this invention helps to promote technological progress in manufacturing, especially in the field of high-precision manufacturing, and provides more efficient and accurate production solutions for related industries. Attached Figure Description

[0023] Figure 1 It is a single-layer side milling machine tool. i Cross-sectional diagram;

[0024] Figure 2 is u i Schematic diagrams of the theoretical and actual tangent lines of the cross-section;

[0025] Figure 3 This is a schematic diagram of the mutual moments of two straight lines in space. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0027] This embodiment provides a method for characterizing the dynamic characteristics of CNC machine tools based on part geometric errors, which can be used to guide CNC machine tool designers in optimizing the design of relevant components. Specifically, it detects the normal deviation of the side-milled part and then uses mathematical methods to calculate the mutual moment of error between the theoretical and actual tangential contact lines during workpiece machining. For parts machined in a single-layer side milling process, there exists a theoretical tangential contact line, i.e., the straight generatrix of that section, in any cutting section. Points are placed on the straight generatrix and its actual three-dimensional coordinates are measured. In three-dimensional space, the theoretical and actual tangential contact lines are fitted based on the theoretical and actual measurement points, respectively. The mutual moment of error between the two spatial lines can be calculated using mathematical methods.

[0028] Specifically, the CNC machine tool dynamic characteristic characterization method provided in this embodiment includes the following steps:

[0029] 1) Perform isoparametric point layout on the side-milled part, with a point count of m×n, where m is the number of measurement points in the u direction and n is the number of measurement points in the v direction. Perform coordinate measuring machine (CMM) inspection to obtain the theoretical point cloud of the measurement points. and actual 3D coordinate point cloud Where i∈[1,m], j∈[1,n]. The surface in parameter (u i ,v j At point ), the theoretical coordinates of the measuring point are: The actual measuring points are

[0030] 2) in u i In the cross section, spatial linear fitting is performed on all theoretical and actual measurement points in the v-direction to solve for the theoretical tangent line. Make it satisfy Distance along the straight line The nearest point; similarly, solve for the actual tangent line. Make it satisfy Distance along the straight line The nearest point. Calculated based on spiral theory. and The Plücker coordinates are used to obtain u. i Theoretical tangent line in the cross section and the actual tangent line in,

[0031] 3) Calculate the angles at u for the two lines according to equation (1). i Cross-sectional error mutual moment:

[0032]

[0033] Specifically, such as Figure 1In this embodiment, a CNC machine tool is used to process the curved surface S. Points are arranged along the u and v directions (equal parameters) on the surface S to be measured, and a coordinate measuring machine is used to obtain point cloud data of theoretical points and measured points. In this embodiment, a segment of data is extracted for analysis; the extracted data is shown in the table below.

[0034]

[0035]

[0036] like Figure 2 Based on the least squares principle, in u i Spatial linear fitting is performed on all theoretical and actual measuring points in the v-direction on the cross section to solve for the theoretical tangent line. and actual contact line And calculate based on spinor theory and The Plücker coordinates are used to obtain u. i Theoretical tangent line in the cross section and the actual tangent line The results are shown in the table below.

[0037]

[0038] Calculate the two lines at u according to equation (2). i Cross-sectional error mutual moment:

[0039]

[0040] In this embodiment, each u i The cross-sectional error moments are shown in the table below;

[0041]

[0042] Figure 3 middle, and They are u i In the cross section, the theoretical tangent line is... and actual contact line The radius vector; the common perpendicular vector of the two lines is in Unit vector, It is the perpendicular distance between two straight lines; It is the angle of twist between the two lines; points A and B are the two feet of the common perpendicular between the two lines.

[0043] Preferably, embodiments of this application also provide a specific implementation of an electronic device capable of implementing all steps in the CNC machine tool dynamic characteristic characterization method based on the traceability of geometric errors in machined parts described in the above embodiments. The electronic device specifically includes the following:

[0044] Processor, memory, communications interface, and bus;

[0045] The processor, memory, and communication interface communicate with each other via a bus; the communication interface is used to realize information transmission between server-side devices, metering devices, and user-side devices.

[0046] The processor is used to call the computer program in the memory. When the processor executes the computer program, it implements all the steps in the CNC machine tool dynamic characteristic characterization method based on the geometric error of the machined part in the above embodiments.

[0047] The embodiments of this application also provide a computer-readable storage medium capable of implementing all steps of the CNC machine tool dynamic characteristic characterization method based on the geometric error of the machined parts in the above embodiments. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements all steps of the multi-axis CNC machine tool dynamic characteristic characterization method based on the geometric error of the machined parts in the above embodiments.

[0048] The foregoing has described specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be performed in a different order than that shown in the embodiments and may still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired result. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0049] While this application provides method operation steps as shown in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-inventive labor. The order of steps listed in the embodiments is merely one possible execution order among many and does not represent the only execution order. In actual device or client product execution, the method can be executed sequentially as shown in the embodiments or drawings, or in parallel (e.g., in a parallel processor or multi-threaded processing environment).

[0050] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0051] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0052] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0053] This invention is not limited to the embodiments described above. The above description of specific embodiments is intended to illustrate and explain the technical solutions of this invention. The specific embodiments described above are merely illustrative and not restrictive. Without departing from the spirit and scope of the claims, those skilled in the art can make many specific modifications based on the teachings of this invention, and these modifications all fall within the scope of protection of this invention.

Claims

1. A method for characterizing the dynamic characteristics of CNC machine tools based on tracing the source of geometric errors in machined parts, characterized in that, Used to characterize the dynamic characteristics of CNC machine tools, including: 1) Perform isoparametric point layout on the machined parts, with a point count of m×n, where m is the number of measurement points in the u direction and n is the number of measurement points in the v direction; perform coordinate measuring machine (CMM) inspection to obtain the theoretical point cloud of the measurement points. and actual 3D coordinate point cloud ; Surface in parameters At this location, the theoretical coordinates of the measuring point are: The actual measuring points are ; 2) in u i In the cross section, spatial linear fitting is performed on all theoretical and actual measurement points in the v-direction to solve for the theoretical tangent line. To satisfy , Distance along the straight line The nearest point; similarly, solve for the actual tangent line. To satisfy , Distance along the straight line The nearest point; calculated based on spiral theory and The Plücker coordinates are used to obtain u. i Theoretical tangent line in the cross section and the actual tangent line ; 3) Calculate the mutual moments of the errors between the two lines: .

2. The method for characterizing the dynamic characteristics of CNC machine tools according to claim 1, characterized in that, The error cross-moment originates from the geometric error distribution pattern of the parts processed by the machine tool.

3. The method for characterizing the dynamic characteristics of CNC machine tools according to claim 1, characterized in that, Actual measuring points on the machined parts u cross section v It tends to be approximately linearly distributed.

4. The method for characterizing the dynamic characteristics of CNC machine tools according to claim 1, characterized in that, The actual three-dimensional coordinate point cloud of the machined part can be linearly fitted into an actual tangent line in space.

5. The method for characterizing the dynamic characteristics of a CNC machine tool according to claim 4, characterized in that, The actual tangential line can be solved for its Plücker coordinates based on the spiral theory.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the CNC machine tool dynamic characteristic characterization method according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the CNC machine tool dynamic characteristic characterization method according to any one of claims 1 to 5.

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