A high-precision geometric error detection method and system for five-axis CNC machining

Abstract

The present invention relates to the technical field of five-axis CNC machining error detection, and specifically to a high-precision geometric error detection method and system for five-axis CNC machining, comprising: obtaining the height error value and height error matrix of the measurement point on the worktable surface through a laser interferometer; determining the ultimate probability of deformation of the height error matrix in the corresponding area of ​​the worktable surface; determining the deformation amount of the worktable surface at each measurement; determining the rate of change of the deformation amount of the worktable surface in the most recent measurement; determining the final deformation amount of the position of the workpiece on the worktable surface at each moment; and compensating the five-axis CNC machining machine according to the final deformation amount. The present invention reduces the dynamic influence of the deformation of the worktable surface that accumulates over time and the influence of the workpiece's own weight on the worktable surface, which is conducive to improving the overall machining performance of the five-axis CNC machining machine.

Description

Technical Field

[0001] The present invention relates to the technical field of five-axis CNC machining error detection, and in particular to a high-precision geometric error detection method and system for five-axis CNC machining. Background Art

[0002] Five-axis CNC machining technology, with its high efficiency, flexibility, and precision, has been widely used in fields such as mold processing. Five-axis CNC machine tools can simultaneously control the motion of five coordinate axes, enabling high-precision machining of complex curved surfaces and special-shaped parts. To meet increasingly stringent machining requirements and ensure part quality, high-precision deformation error detection during five-axis CNC machining has become crucial.

[0003] In the field of error detection for five-axis CNC machine tools, existing techniques for detecting deformation errors in the workpiece's position on the worktable surface use laser interferometers to measure the deformation error at each measurement point on the worktable surface, thereby inferring the deformation error of the workpiece's position. However, this method has certain limitations in its implementation: it fails to fully account for the dynamic characteristics of the worktable surface, which gradually increases in deformation over time, as well as the influence of the workpiece's own weight on the worktable surface. This results in a decrease in the accuracy of deformation error detection, which in turn affects the real-time and precision of subsequent compensation measures. Summary of the Invention

[0004] To solve the above problems, the present invention provides a high-precision geometric error detection method and system for five-axis CNC machining.

[0005] The present invention provides a high-precision geometric error detection method and system for five-axis CNC machining using the following technical solutions:

[0006] An embodiment of the present invention provides a high-precision geometric error detection method for five-axis CNC machining, the method comprising the following steps:

[0007] The height error values ​​of several preset measuring points on both sides of the support axis of the worktable of the five-axis CNC machine tool are measured multiple times by a laser interferometer. The height error values ​​of all measuring points on the worktable surface measured each time are used to form a height error matrix.

[0008] For the most recently measured height error matrix, obtain the symmetry axis corresponding to the support axis of the worktable surface in the height error matrix; obtain the distance between the workpiece on the worktable surface and the support axis at each moment; and determine the ultimate probability of deformation of the height error matrix in the corresponding area of ​​the worktable surface by analyzing the difference changes between adjacent height error values ​​along one side of the symmetry axis in each row of the height error matrix and the similarity of height error values ​​at symmetrical positions on both sides of the symmetry axis in each row.

[0009] The irregularity of the height error matrix in the corresponding area of ​​the workbench surface is determined by calculating the sum of the differences in the changes in adjacent height error values ​​in different rows in the height error matrix; the deformation of the workbench surface at each measurement is determined by combining the final probability and the irregularity; and the rate of change of the deformation of the workbench surface at the most recent measurement is determined based on the difference in deformation between the most recent measurement and historical measurements of the workbench surface.

[0010] Based on the deformation change rate of the most recent measurement, the deformation of the worktable surface at each moment from the most recent measurement to the next measurement is estimated; based on the estimated deformation and the distance of the workpiece from the support axis at each moment, the final deformation of the workpiece at each moment on the worktable surface is determined; and based on the final deformation, the five-axis CNC machining center is compensated.

[0011] Furthermore, the method determines the ultimate possibility of deformation of the height error matrix in the corresponding area of ​​the worktable surface by analyzing the difference changes between adjacent height error values ​​along one side of the symmetry axis in each row of the height error matrix and the similarity of the height error values ​​at symmetrical positions on both sides of the symmetry axis in each row, and includes the following specific steps:

[0012]

[0013] Where, is the height error matrix The number of height error values ​​of the row along the right side of the symmetry axis; is the height error matrix The row along the right side of the symmetry axis Height error value; is the height error matrix The row along the right side of the symmetry axis Height error value; is an exponential function with a natural constant as its base; is a linear normalization function; is the height error matrix The initial possibility of deformation of the corresponding area on the workbench surface to the right of the symmetry axis;

[0014] By analyzing the similarity of the height error values ​​of each row in the height error matrix at the symmetrical positions along the symmetry axis, the credibility of the deformation of the corresponding area on the worktable surface in each row is evaluated;

[0015] The final probability of deformation of the height error matrix in the corresponding area of ​​the workbench surface is determined by combining the initial possibility and credibility.

[0016] Furthermore, the reliability of deformation of the corresponding area of ​​each row on the worktable surface is evaluated by analyzing the similarity of the height error values ​​of the symmetrical positions of each row along the symmetry axis in the height error matrix, including the following specific steps:

[0017]

[0018] Where, is the height error matrix The number of height error values ​​along one side of the symmetry axis; is the height error matrix The left side of the symmetry axis Height error value; To take the absolute value; is the preset hyperparameter; is the height error matrix The reliability of the deformation of the corresponding area on the workbench surface.

[0019] Furthermore, the above-mentioned initial possibility and credibility are integrated to determine the final possibility of deformation of the height error matrix in the corresponding area of ​​the worktable surface, including the following specific steps:

[0020]

[0021] Where, is the number of rows in the height error matrix; is the height error matrix The credibility of the deformation of the corresponding area on the workbench surface; is the final possibility of deformation of the corresponding area of ​​the workbench surface due to the height error matrix.

[0022] Furthermore, the irregularity of the height error matrix in the corresponding area of ​​the workbench surface is determined by calculating the sum of the differences in the changes in adjacent height error values ​​between different rows in the height error matrix, which includes the following specific steps:

[0023]

[0024] Where, is the number of rows in the height error matrix; is the number of height error values ​​contained in a single row in the height error matrix; is the height error matrix No. within the line The height error value is the same as the The absolute difference of the height error values; is the height error matrix No. within the line The height error value is the same as the The absolute difference of the height error values; To take the absolute value; is the irregularity of the height error matrix in the corresponding area of ​​the workbench surface.

[0025] Furthermore, the comprehensive final probability and irregularity are used to determine the deformation amount of the workbench surface at each measurement, including the following specific steps:

[0026]

[0027] Where, is the final possibility of deformation in the corresponding area on the worktable surface along the right side of the symmetry axis in the height error matrix; is the flatness of the corresponding area of ​​the height error matrix on the workbench surface; It is the most recently measured deformation of the workbench surface.

[0028] Furthermore, the method of determining the change rate of the deformation variable of the workbench surface measured most recently based on the difference between the deformation variables of the workbench surface measured most recently and those measured historically includes the following specific steps:

[0029]

[0030] Where, The number of historical measurements closest to the most recent measurement. It is the fixed interval between two adjacent measurements on the workbench surface; The history of the workbench surface closest to the most recent measurement The deformation amount of the secondary measurement; The history of the workbench surface closest to the most recent measurement The deformation amount of the secondary measurement; To take the absolute value; It is the rate of change of deformation of the workbench surface measured most recently.

[0031] Furthermore, the method of estimating the deformation of the workbench surface at each moment between the last measurement and the next measurement based on the deformation change rate of the last measurement includes the following specific steps:

[0032]

[0033] Where, is the most recently measured deformation of the workbench surface; The rate of change of the deformation of the workbench surface measured most recently; The period from the last measurement to the next measurement on the workbench surface. a moment; It is the fixed interval between two adjacent measurements on the workbench surface; The period from the last measurement to the next measurement on the workbench surface. The deformation at a moment.

[0034] Furthermore, the method of determining the final deformation of the workpiece at each moment on the worktable surface based on the estimated deformation and the distance between the workpiece and the support axis at each moment includes the following specific steps:

[0035]

[0036] Where, The period from the last measurement to the next measurement on the workbench surface. The deformation at each moment; The workpiece on the workbench surface is The distance from the position at each moment to the support axis; The maximum distance from the measuring point on the workbench surface to the support axis; The position of the workpiece on the workbench surface is The final deformation at a certain moment.

[0037] The present invention also proposes a high-precision geometric error detection system for five-axis CNC machining, comprising a memory and a processor, wherein the processor executes a computer program stored in the memory to implement the steps of the aforementioned method.

[0038] The beneficial effect of the technical solution of the present invention is as follows: according to the present invention, in the process of detecting the deformation error of the workpiece at the position on the worktable surface of the five-axis CNC machining machine, the dynamic characteristics of the deformation of the worktable surface that gradually increases with time and the influence of the workpiece's own weight on the worktable surface can be fully considered, and by analyzing the estimated deformation and the distance between the position of the workpiece on the worktable surface and the support axis, the final deformation of the position of the workpiece on the worktable surface at each moment is determined, and then the five-axis CNC machining machine is compensated based on the final deformation. When determining that the worktable surface has been deformed, by analyzing the difference between the adjacent height error values ​​along one side of the symmetry axis in each row of the height error matrix and the similarity of the height error values ​​of the symmetrical positions on both sides of the symmetry axis in each row, the final possibility of deformation of the height error matrix in the corresponding area of ​​the worktable surface is determined, thereby improving the scientificity, accuracy and objectivity of the deformation analysis. When determining the estimated deformation, the deformation change rate of the worktable surface measured most recently is analyzed, and then the estimated deformation at each time before the next measurement is determined based on the deformation change rate. This reduces the impact of the dynamic characteristics of the worktable surface deformation that accumulates over time on the detection, which is beneficial to improving the overall processing performance of the five-axis CNC machining center. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 A flowchart of a high-precision geometric error detection method for five-axis CNC machining provided by one embodiment of the present invention;

[0041] Figure 2 A schematic diagram of a five-axis CNC machine tool provided by one embodiment of the present invention;

[0042] Figure 3 A basic schematic diagram of the measurement principle of a laser interferometer provided by one embodiment of the present invention;

[0043] Figure 4 A schematic diagram of a scenario in which a laser interferometer is used to measure the height error value of a measuring point on the surface of a five-axis CNC machine tool worktable according to an embodiment of the present invention;

[0044] Figure 5 A schematic diagram of obtaining a height error matrix according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] To further illustrate the technical means and effectiveness of the present invention in achieving its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail a high-precision geometric error detection method and system for five-axis CNC machining according to the present invention, including its specific implementation, structure, features, and effectiveness. In the following description, references to different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0046] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0047] The following describes in detail a high-precision geometric error detection method and system for five-axis CNC machining provided by the present invention with reference to the accompanying drawings.

[0048] See also Figure 1 , which shows a flowchart of a high-precision geometric error detection method for five-axis CNC machining provided by one embodiment of the present invention, the method comprising the following steps:

[0049] Step S001: Use a laser interferometer to measure the height error values ​​of several preset measurement points on the worktable surface of a five-axis CNC machine tool along both sides of the support axis multiple times. The height error values ​​of all measurement points on the worktable surface measured each time constitute a height error matrix.

[0050] It should be noted that the main purpose of this embodiment is to detect the final deformation of the workpiece at each moment on the surface of the five-axis CNC machining center's worktable. The final deformation reflects the geometric error of the five-axis CNC machining center. Before starting the detection, the height error values ​​of several preset measurement points on both sides of the support axis on the surface of the five-axis CNC machining center's worktable are first measured multiple times by a laser interferometer for subsequent error detection and analysis.

[0051] It should be noted that this implementation mainly analyzes the worktable surface of the X-axis of the five-axis CNC machining center and a support shaft under the worktable surface. Figure 2 , Figure 2 Schematic diagram of the five-axis CNC machining center of this embodiment. Figure 2 Our five-axis CNC machining centers include:

[0052] X-axis: The main axis of the machine tool, which moves in the horizontal direction and is responsible for radial cutting of the workpiece.

[0053] Y-axis: perpendicular to the X-axis, usually moves on the horizontal plane, responsible for the lateral cutting of the workpiece.

[0054] Z-axis: perpendicular to the X-axis and Y-axis, it is the vertical axis of the machine tool and is responsible for the depth of cutting of the workpiece.

[0055] A-axis: Rotation axis, runs the tool to rotate around the X-axis.

[0056] C-axis: Tool axis, allows the tool or workpiece to rotate around the Z-axis, providing convenience for processing various complex surfaces.

[0057] The long platform between the X-axis and the Y-axis is the workbench analyzed in this embodiment, and the two sliding force-bearing tracks parallel to the X-axis are the support axes analyzed in this embodiment. This embodiment mainly analyzes one of the force-bearing tracks, i.e., one support axis. For details about the sliding force-bearing track, please refer to Figure 4 The content in.

[0058] It should be further explained that, in this embodiment, the height error values ​​of several preset measuring points on both sides of the support axis of the worktable surface of the five-axis CNC machine tool are measured multiple times by a laser interferometer. The specific measurement principle is a well-known technology and will not be described in detail in this embodiment. Figure 3 , Figure 3 This is a basic diagram of the laser interferometer measurement principle. Figure 3It includes a laser head, an interferometer and a reflector. The laser head is the light source of the laser interferometer. It emits a monochromatic, highly coherent laser beam. This laser beam is the basis for the operation of the interferometer. Interferometer: The interferometer is usually a beam splitter. It splits the laser beam into two beams, one of which is reflected and the other is transmitted. These two beams propagate along different paths. Reflector: The reflector is used to reflect the laser beam. In the interferometer, there are usually two reflectors, one fixed and the other movable. The position change of the movable reflector will cause an optical path difference, thereby generating interference. The laser interferometer has a high-precision acquisition effect and can measure and analyze a variety of geometric quantities and dynamic characteristics, that is, it can obtain the change data of the height of the worktable surface. Therefore, this embodiment uses a laser interferometer to repeatedly measure the height error values ​​of several preset measurement points on the surface of the five-axis CNC machine tool along both sides of the support axis.

[0059] For further explanation, please refer to Figure 4 , Figure 4 This is a schematic diagram of a scenario in which a laser interferometer is used to measure the height error value of a measuring point on the surface of a five-axis CNC machine tool worktable in this embodiment. Figure 4 The laser head, interferometer and reflector are already in Figure 3 The laser head and the interferometer are fixed, and the reflector is fixed on the surface of the workbench. In this embodiment, multiple reflectors are included. Figure 4 Only one reflector is shown in the figure. Multiple reflectors are in the same plane and parallel to the moving direction of the workbench. Each reflector position is regarded as a measuring point. During subsequent measurements, each measuring point has a height error value each time. Multiple reflectors are arranged at equal intervals. In this embodiment, the interval between adjacent reflectors is 15 mm, which can be adjusted according to actual implementation conditions and is not limited in this embodiment.

[0060] Specifically, the height error values ​​of several preset measuring points on both sides of the support axis of the worktable surface of the five-axis CNC machine tool are measured multiple times by a laser interferometer. The height error values ​​of all measuring points on the worktable surface measured each time constitute a height error matrix, which is as follows:

[0061] The above respectively introduces the measurement principle of laser interferometer and the scenario of measuring the height error value of the measuring point on the surface of the worktable of a five-axis CNC machine tool by laser interferometer. During the specific measurement, the worktable of the five-axis CNC machine tool is first moved to one side, and then moved to the other side to start obtaining the height error value. The moving speed of the worktable in this embodiment is a uniform motion of 1000mm / min. As the worktable moves, the reflector fixed on the worktable also starts to move. The laser head can irradiate multiple reflectors in turn, and then obtain a column of height error values. The specific reference to the acquisition of height error values ​​is "The height error value is obtained by referring to the article published by the authors Ji Zeping, Tian Chunmiao, Guo Shijie, Tang Shufeng and Lan Yuezheng in the journal "Mechanical and Electrical Engineering" in January 2024. The content disclosed on page 170 of "Single-axis five-time measurement and identification method of geometric errors of CNC machine tools"; then continue to move the multiple reflectors toward the support axis, each movement is also 15 mm, and again move the workbench of the five-axis CNC machine tool to one side, and then move to the other side to start obtaining height error values, and then obtain another column of height error values, and so on, to obtain multiple columns of height error values, form a height error matrix, and complete a measurement. This embodiment requires multiple measurements, and the time interval between two adjacent measurements is 2 days, that is, 48 ​​hours.

[0062] It should be noted that if the five-axis CNC machining center is used for the first time, since the machine tool has been used for a short time and the deformation is small, the data of the first five measurements are ignored in this embodiment, that is, the measurement data of the initial use of the machine tool is not analyzed.

[0063] For clarification, please refer to Figure 5 , Figure 5 This is a schematic diagram of obtaining the height error matrix in this embodiment. Figure 5 It includes multiple measurement points, each measurement point corresponds to a height error value, and then a height error matrix can be determined. Figure 5 The dotted line in the middle is the support axis corresponding to the workbench. It should be noted that this embodiment mainly analyzes one support axis of the workbench, that is, only half of the workbench surface is analyzed. The analysis method for the other half of the workbench surface is the same, and the two parts are structurally symmetrical.

[0064] At this point, the height error values ​​of several preset measurement points on the surface of the five-axis CNC machine tool worktable along both sides of the support axis are measured multiple times by laser interferometer. The height error values ​​of all measurement points on the worktable surface measured each time constitute a height error matrix.

[0065] Step S002: for the height error matrix measured most recently, obtain the symmetry axis corresponding to the support axis of the worktable surface in the height error matrix; obtain the distance between the position of the workpiece on the worktable surface and the support axis at each moment; and determine the final possibility of deformation of the height error matrix in the corresponding area of ​​the worktable surface by analyzing the difference changes between adjacent height error values ​​along one side of the symmetry axis in each row of the height error matrix and the similarity of the height error values ​​at symmetrical positions on both sides of the symmetry axis in each row.

[0066] It should be noted that, in order to facilitate subsequent analysis, the symmetry axis of the height error matrix is ​​first obtained based on the support axis of the workbench surface.

[0067] Specifically, for the height error matrix measured most recently, the symmetry axis corresponding to the support axis of the worktable surface in the height error matrix is ​​obtained.

[0068] It should be noted that all the measuring points on the workbench surface can be regarded as a measuring point matrix. The support axis of the workbench surface is located at the symmetry axis of the measuring point matrix. For details, please refer to Figure 5 , Figure 5 The dotted line in the middle is the support axis corresponding to the workbench, that is, the corresponding symmetry axis position in the height error matrix.

[0069] Furthermore, the distance between the position of the workpiece on the worktable surface and the support shaft at each moment is obtained.

[0070] It should be noted that obtaining the distance between the workpiece on the worktable surface and the support axis at each moment is an existing method and will not be repeated in this embodiment. It can be determined by measuring the Euclidean distance from the center of mass of the workpiece to the support axis.

[0071] It should be noted that for measurement points symmetrically located on either side of the support axis, deformation generally occurs to a similar degree within the same timeframe. Furthermore, measurement points farther from the support axis tend to deform more, while measurement points closer to the support axis tend to deform less. The greater the deformation, the greater the height error value of the measurement point. Therefore, by analyzing the similarity between the deformation changes at measurement points on one side of the support axis and the deformation changes at symmetrical locations on both sides, we determine the ultimate probability of deformation occurring in the corresponding area of ​​the worktable surface within the height error matrix. This deformation change is reflected in the height error value.

[0072] Specifically, by analyzing the difference between the adjacent height error values ​​along one side of the symmetry axis in each row of the height error matrix and the similarity of the height error values ​​at symmetrical positions on both sides of the symmetry axis in each row, the final possibility of deformation of the height error matrix in the corresponding area of ​​the worktable surface is determined. The steps include:

[0073] First, by analyzing the difference changes between adjacent height error values ​​along one side of the symmetry axis in each row of the height error matrix, the initial possibility of deformation in the corresponding area of ​​the workbench surface along one side of the symmetry axis in each row is evaluated.

[0074] Secondly, by analyzing the similarity of the height error values ​​of each row in the height error matrix at the symmetrical positions on both sides of the symmetry axis, the credibility of the deformation of each row in the corresponding area of ​​the workbench surface is evaluated.

[0075] Finally, the initial possibility and credibility are combined to determine the final possibility of deformation of the height error matrix in the corresponding area of ​​the workbench surface.

[0076] Specifically, by analyzing the difference between the adjacent height error values ​​along the symmetry axis of each row in the height error matrix, the initial possibility of deformation in the corresponding area of ​​the worktable surface along the symmetry axis of each row is evaluated, as follows:

[0077]

[0078] Where, is the height error matrix The number of height error values ​​of the row along the right side of the symmetry axis; is the height error matrix The row along the right side of the symmetry axis Height error value; is the height error matrix The row along the right side of the symmetry axis Height error value; is an exponential function with a natural constant as its base; is a linear normalization function used for normalization processing; is the height error matrix The initial possibility of deformation of the corresponding area on the workbench surface to the right of the symmetry axis.

[0079] What needs to be explained is that Indicates the deformation trend change between adjacent measuring points far away from the support axis, which is reflected by the difference between the height error values. Since the deformation trend of the measuring points far away from the support axis on the workbench surface is larger, if The larger the value, the greater the deformation trend of the measurement point far away from the support axis. The exponential function is used to amplify the deformation trend change and accumulate the height error matrix. The increasing trend of deformation occurs in the corresponding area on the workbench surface along the right side of the symmetry axis, and the The initial possibility of deformation of the corresponding area on the workbench surface to the right of the symmetry axis, The larger it is, the greater the initial probability of deformation.

[0080] Furthermore, by analyzing the similarity of the height error values ​​of the symmetrical positions along the symmetry axis in each row of the height error matrix, the credibility of the deformation of the corresponding area on the worktable surface in each row is evaluated as follows:

[0081]

[0082] Where, is the height error matrix The number of height error values ​​along one side of the symmetry axis. It should be noted that the number of height error values ​​along both sides of the symmetry axis in the height error matrix is ​​equal; is the height error matrix The row along the right side of the symmetry axis Height error value; is the height error matrix The left side of the symmetry axis Height error value; To take the absolute value; is a preset hyperparameter, the purpose of which is to prevent the denominator from being 0. In this embodiment, to give a narrative; is the height error matrix The reliability of the deformation of the corresponding area on the workbench surface.

[0083] What needs to be explained is that Indicates the similarity of the height error values ​​of the symmetrical measuring points on the worktable surface along the support axis. For the symmetrical measuring points on both sides of the support axis, the degree of deformation in the same time is generally similar. The smaller the height error matrix is, the The higher the confidence level, the more likely the deformation occurs in the corresponding area of ​​the workbench surface.

[0084] It should be noted that the above evaluation and analysis separately evaluated the initial possibility of each row in the height error matrix being deformed in the corresponding area of ​​the workbench surface along one side of the symmetry axis, and the credibility of each row being deformed in the corresponding area of ​​the workbench surface. These two indicators are combined to more accurately determine the final possibility of the height error matrix being deformed in the corresponding area of ​​the workbench surface.

[0085] Furthermore, the final probability of deformation of the height error matrix in the corresponding area of ​​the worktable surface is determined by combining the initial probability and credibility, as follows:

[0086]

[0087] Where, is the number of rows in the height error matrix; is the height error matrix The initial possibility of deformation of the corresponding area on the workbench surface to the right of the symmetry axis; is the height error matrix The credibility of the deformation of the corresponding area on the workbench surface; is the final possibility of deformation of the corresponding area of ​​the workbench surface due to the height error matrix.

[0088] What needs to be explained is that when the height error matrix The greater the initial possibility of deformation in the corresponding area on the worktable surface along the right side of the symmetry axis, the greater the initial possibility of deformation in the corresponding area on the worktable surface. The higher the confidence that the row is deformed in the corresponding area of ​​the workbench surface, the greater the possibility that the height error matrix is ​​deformed in the corresponding area of ​​the workbench surface, that is, the greater the final probability.

[0089] It should be noted that, in this embodiment, the height error matrix The initial possibility of deformation on the corresponding area on the workbench surface on the right side of the symmetry axis is used to replace the initial possibility of deformation on the corresponding area on the workbench surface on both sides. When deformation occurs, the deformation conditions on both sides of the symmetry axis are similar.

[0090] At this point, the final possibility of deformation of the corresponding area of ​​the workbench surface in the height error matrix is ​​determined.

[0091] Step S003: Determine the irregularity of the height error matrix in the corresponding area of ​​the workbench surface by calculating the sum of the differences in the changes in adjacent height error values ​​between different rows in the height error matrix; determine the deformation of the workbench surface each time measured based on the final probability and the irregularity; determine the rate of change of the deformation of the workbench surface in the most recent measurement based on the difference in deformation between the most recent measurement and the historical measurement.

[0092] It should be noted that, under normal circumstances, the distance from the measuring point to the support axis is the same, and the change in the height error value of adjacent measuring points along the support axis is also similar. If the change in the height error value of adjacent measuring points along the support axis is significantly different, it means that the deformation of the workbench surface is irregular.

[0093] Specifically, the irregularity of the height error matrix in the corresponding area of ​​the workbench surface is determined by calculating the sum of the differences in the changes in the adjacent height error values ​​between different rows in the height error matrix, as follows:

[0094]

[0095] Where, is the number of rows in the height error matrix; is the number of height error values ​​contained in a single row in the height error matrix; is the height error matrix No. within the line The height error value is the same as the The absolute difference of the height error values; is the height error matrix No. within the line The height error value is the same as the The absolute difference of the height error values; To take the absolute value; is the irregularity of the height error matrix in the corresponding area of ​​the workbench surface.

[0096] What needs to be explained is that It indicates that the changes in the height error values ​​of two adjacent measurement points parallel to the worktable surface and the support axis are similar. If the changes in the height error values ​​of adjacent measurement points along the support axis are significantly different, it means that the irregularity of the worktable surface is greater.

[0097] It should be noted that the irregular deformation of the workbench surface is caused by a combination of various reasons. The irregularity combined with the final possibility can be used to obtain the deformation of the workbench surface in the current measurement.

[0098] Furthermore, the deformation amount of the workbench surface at each measurement is determined by combining the final probability and irregularity, as follows:

[0099]

[0100] Where, is the final possibility of deformation in the corresponding area on the worktable surface along the right side of the symmetry axis in the height error matrix; is the flatness of the corresponding area of ​​the height error matrix on the workbench surface; It is the most recently measured deformation of the workbench surface.

[0101] It should be noted that the analysis process of the deformation variables of other measurements on the workbench surface is the same as that of the most recent measurement. The above analysis analyzes the deformation variables of the most recent measurement on the workbench surface. Similarly, the deformation variables of other measurements can also be obtained, and then the deformation variables of each measurement on the workbench surface can be determined. The details will not be repeated here.

[0102] Furthermore, based on the difference between the deformation variables of the workbench surface measured most recently and those measured historically, the deformation variable change rate of the workbench surface measured most recently is determined, as follows:

[0103]

[0104] Where, is the preset number of historical measurements closest to the most recent measurement. For explanation, the number of historical measurements includes the most recent measurement; The fixed interval between two adjacent measurements on the workbench surface is in hours. In this embodiment, ; The history of the workbench surface closest to the most recent measurement The deformation amount of the secondary measurement; The history of the workbench surface closest to the most recent measurement The deformation amount of the secondary measurement; To take the absolute value; It is the rate of change of deformation of the workbench surface measured most recently.

[0105] It should be noted that by calculating the average deformation change of the five historical measurements, the deformation change rate of the workbench surface in the most recent measurement is obtained, which can reflect the change of the deformation during the next measurement. In this embodiment, it is assumed that the deformation change rate remains constant from the most recent measurement to the next measurement period.

[0106] At this point, the rate of change of the deformation of the workbench surface measured most recently is determined.

[0107] Step S004: Estimate the deformation of the worktable surface at each moment from the most recent measurement to the next measurement based on the deformation change rate of the most recent measurement; determine the final deformation of the workpiece on the worktable surface at each moment based on the estimated deformation and the distance of the workpiece from the support axis at each moment; and compensate the five-axis CNC machining center based on the final deformation.

[0108] It should be noted that the above determines the rate of change of the deformation variable of the worktable surface at the most recent measurement. Next, based on the rate of change of the deformation variable, the final deformation variable at any moment during the next measurement in the future is predicted. The final deformation variable reflects the geometric error of the five-axis CNC machining machine tool, and then the five-axis CNC machining machine tool is compensated according to the final deformation variable of the position of the workpiece on the worktable surface at each moment.

[0109] Specifically, based on the deformation change rate of the most recent measurement, the deformation of the workbench surface at each moment from the most recent measurement to the next measurement is estimated as follows:

[0110]

[0111] Where, is the most recently measured deformation of the workbench surface; The rate of change of the deformation of the workbench surface measured most recently; The period from the last measurement to the next measurement on the workbench surface. a moment; It is the fixed interval between two adjacent measurements on the workbench surface; The period from the last measurement to the next measurement on the workbench surface. The deformation at a moment.

[0112] What needs to be explained is that Represents the increment of deformation over time. The larger the value, the greater the increment of the deformation variable. .

[0113] Furthermore, based on the estimated deformation amount and the distance between the workpiece and the support axis at each moment, the final deformation amount of the workpiece at each moment on the worktable surface is determined as follows:

[0114]

[0115] Where, The period from the last measurement to the next measurement on the workbench surface. The deformation at each moment; The workpiece on the workbench surface is The distance from the position at each moment to the support axis; The maximum distance from the measuring point on the workbench surface to the support axis; The position of the workpiece on the workbench surface is The final deformation at a certain moment.

[0116] It should be noted that the farther the workpiece is from the support shaft, the weaker the support shaft is, and the greater the final deformation of the workpiece is. The larger the size, the higher the position of the workpiece on the worktable surface. The larger the final deformation at a moment, the more the final deformation reflects the geometric error of the five-axis CNC machining machine tool.

[0117] It should be noted that the above determines the final deformation of the workpiece at each moment on the worktable surface. Next, the five-axis CNC machining machine is compensated based on the final deformation.

[0118] Specifically, the five-axis CNC machining machine tool is compensated according to the final deformation amount.

[0119] It should be noted that the existing method is to compensate the five-axis CNC machining center according to the final deformation of the workpiece on the worktable surface at each moment. For details, please refer to the "Error Compensation Experiment" section on pages 136 to 137 of the article "Geometric Error Analysis and Compensation of the Rotating Axis of Five-Axis Machine Tools" published by authors Guo Shijie and Zhang Dongsheng in the journal "Engineering Science and Technology" in March 2020.

[0120] Through the above steps, a high-precision geometric error detection method for five-axis CNC machining is completed.

[0121] Another embodiment of the present invention provides a high-precision geometric error detection system for five-axis CNC machining, the system comprising a memory and a processor, wherein when the processor executes a computer program stored in the memory, the processor performs the following operations:

[0122] The laser interferometer is used to measure the height error values ​​of several preset measuring points on both sides of the support axis of the worktable surface of the five-axis CNC machining center multiple times. The height error values ​​of all measuring points on the worktable surface measured each time constitute a height error matrix; for the height error matrix of the most recent measurement, the symmetry axis corresponding to the support axis of the worktable surface in the height error matrix is ​​obtained; the distance between the position of the workpiece on the worktable surface and the support axis at each moment is obtained; by analyzing the difference changes between the adjacent height error values ​​along one side of the symmetry axis of each row in the height error matrix and the similarity of the height error values ​​of the symmetrical positions on both sides of the symmetry axis of each row, the final possibility of deformation of the height error matrix in the corresponding area of ​​the worktable surface is determined; by calculating the height error The sum of the differences in the changes in the adjacent height error values ​​between different rows in the matrix is ​​used to determine the irregularity of the height error matrix in the corresponding area of ​​the worktable surface; the deformation of the worktable surface measured each time is determined by combining the final possibility and the irregularity; the rate of change of the deformation of the worktable surface measured in the most recent measurement is determined based on the difference in the deformation between the most recent measurement and the historical measurement; the deformation of the worktable surface at each moment from the most recent measurement to the next measurement is estimated based on the rate of change of the deformation in the most recent measurement; the final deformation of the workpiece at each moment on the worktable surface is determined based on the estimated deformation and the distance from the workpiece to the support axis at each moment; and the five-axis CNC machining machine is compensated based on the final deformation.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high-precision geometric error detection method for five-axis CNC machining, characterized in that: The method comprises the following steps: The height error values ​​of several preset measuring points on both sides of the support axis of the worktable of the five-axis CNC machine tool are measured multiple times by a laser interferometer. The height error values ​​of all measuring points on the worktable surface measured each time are used to form a height error matrix. For the most recently measured height error matrix, obtain the symmetry axis corresponding to the support axis of the worktable surface in the height error matrix; obtain the distance between the workpiece on the worktable surface and the support axis at each moment; and determine the ultimate probability of deformation of the height error matrix in the corresponding area of ​​the worktable surface by analyzing the difference changes between adjacent height error values ​​along one side of the symmetry axis in each row of the height error matrix and the similarity of height error values ​​at symmetrical positions on both sides of the symmetry axis in each row. The irregularity of the height error matrix in the corresponding area of ​​the workbench surface is determined by calculating the sum of the differences in the changes in adjacent height error values ​​in different rows in the height error matrix; the deformation of the workbench surface at each measurement is determined by combining the final probability and the irregularity; and the rate of change of the deformation of the workbench surface at the most recent measurement is determined based on the difference in deformation between the most recent measurement and historical measurements of the workbench surface. Based on the deformation change rate of the most recent measurement, the deformation of the worktable surface at each moment between the most recent measurement and the next measurement is estimated; based on the estimated deformation and the distance of the workpiece from the support axis at each moment, the final deformation of the workpiece at each moment on the worktable surface is determined; and the five-axis CNC machining tool is compensated based on the final deformation. The method of determining the irregularity of the height error matrix in the corresponding area of ​​the workbench surface by calculating the sum of the differences in the changes in adjacent height error values ​​between different rows in the height error matrix includes the following specific steps: Where, is the number of rows in the height error matrix; is the number of height error values ​​contained in a single row in the height error matrix; is the height error matrix No. within the line The height error value is the same as the The absolute difference of the height error values; is the height error matrix No. within the line The height error value is the same as the The absolute difference of the height error values; To take the absolute value; is the irregularity of the height error matrix in the corresponding area of ​​the workbench surface; The above-mentioned comprehensive final probability and irregularity are used to determine the deformation amount of the workbench surface at each measurement, and the specific steps include the following: Where, is the final possibility of deformation in the corresponding area on the worktable surface along the right side of the symmetry axis in the height error matrix; is the flatness of the corresponding area of ​​the height error matrix on the workbench surface; is the most recently measured deformation of the workbench surface; The method of determining the change rate of the deformation variable of the workbench surface measured most recently based on the difference between the deformation variables of the workbench surface measured most recently and those measured historically includes the following specific steps: Where, The number of historical measurements closest to the most recent measurement. It is the fixed interval between two adjacent measurements on the workbench surface; The history of the workbench surface closest to the most recent measurement The deformation amount of the secondary measurement; The history of the workbench surface closest to the most recent measurement The deformation amount of the secondary measurement; To take the absolute value; The rate of change of the deformation of the workbench surface measured most recently; The method of estimating the deformation of the workbench surface at each moment from the last measurement to the next measurement based on the deformation change rate of the last measurement includes the following specific steps: Where, is the most recently measured deformation of the workbench surface; The rate of change of the deformation of the workbench surface measured most recently; The period from the last measurement to the next measurement on the workbench surface. a moment; It is the fixed interval between two adjacent measurements on the workbench surface; The period from the last measurement to the next measurement on the workbench surface. The deformation at each moment; The method of determining the final deformation of the workpiece at each moment on the worktable surface based on the estimated deformation and the distance between the workpiece and the support axis at each moment includes the following specific steps: Where, The period from the last measurement to the next measurement on the workbench surface. The deformation at each moment; The workpiece on the workbench surface is The distance from the position at each moment to the support axis; The maximum distance from the measuring point on the workbench surface to the support axis; The position of the workpiece on the workbench surface is The final deformation at a certain moment.

2. A high-precision geometric error detection method for five-axis CNC machining according to claim 1, characterized in that: The method determines the final possibility of deformation of the height error matrix in the corresponding area of ​​the worktable surface by analyzing the difference changes between adjacent height error values ​​along one side of the symmetry axis in each row of the height error matrix and the similarity of the height error values ​​at symmetrical positions on both sides of the symmetry axis in each row, and includes the following specific steps: Where, is the height error matrix The number of height error values ​​of the row along the right side of the symmetry axis; is the height error matrix The row along the right side of the symmetry axis Height error value; is the height error matrix The row along the right side of the symmetry axis Height error value; is an exponential function with a natural constant as its base; is a linear normalization function; is the height error matrix The initial possibility of deformation of the corresponding area on the workbench surface to the right of the symmetry axis; By analyzing the similarity of the height error values ​​of each row in the height error matrix at the symmetrical positions along the symmetry axis, the credibility of the deformation of the corresponding area on the worktable surface in each row is evaluated; The final probability of deformation of the height error matrix in the corresponding area of ​​the workbench surface is determined by combining the initial possibility and credibility.

3. A high-precision geometric error detection method for five-axis CNC machining according to claim 2, characterized in that: The reliability of deformation of the corresponding area of ​​the worktable surface in each row is evaluated by analyzing the similarity of the height error values ​​of the symmetrical positions of each row along the symmetry axis in the height error matrix, including the following specific steps: Where, is the height error matrix The number of height error values ​​along one side of the symmetry axis; is the height error matrix The left side of the symmetry axis Height error value; To take the absolute value; is the preset hyperparameter; is the height error matrix The reliability of the deformation of the corresponding area on the workbench surface.

4. A high-precision geometric error detection method for five-axis CNC machining according to claim 2, characterized in that: The above-mentioned initial possibility and credibility are combined to determine the final possibility of deformation of the height error matrix in the corresponding area of ​​the worktable surface, including the following specific steps: Where, is the number of rows in the height error matrix; is the height error matrix The credibility of the deformation of the corresponding area on the workbench surface; is the final possibility of deformation of the corresponding area of ​​the workbench surface due to the height error matrix.

5. A high-precision geometric error detection system for five-axis CNC machining, the system comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is executed by a processor, the steps of a high-precision geometric error detection method for five-axis CNC machining as described in any one of claims 1 to 4 are implemented.

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