Machine tool cutter space pose on-machine measuring device and measuring method thereof

Abstract

The invention discloses a machine tool cutter space pose on-machine measurement device and a measurement method thereof, and the device comprises a calibration module which is installed at one side of a cutter handle of a cutter; a frequency-modulated continuous wave laser interference system and a galvanometer are installed on a vibration isolation workbench of the machine tool, light beams emitted by the frequency-modulated continuous wave laser interference system achieve conversion of a set angle through the galvanometer so as to cover the calibration module, and a space positioning algorithm is adopted to fit the plane where the target ball is located. And obtaining a deviation value between the mass center and the normal vector in two measurement results before and after machining, and taking the deviation value as the tool space pose error before and after machining of the machine tool, so that rapid and high-precision direct measurement of the tool space pose error is realized. The method has the advantages of being large in measurement range, high in measurement precision, simple in structure and low in cost, and the defect that in an existing method, the position and pose errors of the tool are indirectly calculated through an error model is overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of CNC machine tool processing error measurement and compensation, and specifically relates to an on-machine measurement device for the spatial posture of a machine tool tool and a measurement method thereof. Background Art

[0002] As the mother machine of industry, machine tools are one of the important indicators to measure a country's advanced manufacturing level. They are widely used in aerospace, aviation, navigation, automobile, national defense and other fields. Their precision indicators are an important embodiment of product quality assurance. The geometric error and thermal error of five-axis CNC machine tools are one of the main error sources affecting the machining accuracy, accounting for about 60% of the total manufacturing error of the machined parts. This is because in the actual machining process, when the process parameters and the external ambient temperature change, the dynamic motion error and thermal error value of the machine tool will change, which will directly cause the spatial posture error of the tool before and after machining, thereby comprehensively affecting the manufacturing error of the machined parts. Therefore, the measurement and compensation of the spatial posture error of machine tool tools is an important means to improve the accuracy of CNC machine tools. The spatial error of the comprehensive machining accuracy of five-axis machine tools is a key factor in determining its machining performance. In the existing commonly used machine tool measurement methods, offline measurement is mostly performed with the help of independent instruments (such as laser interferometers, laser trackers, ballbars, etc.). There is no effective means to achieve in-situ on-machine measurement of spatial errors that integrate multiple items such as geometric errors and thermal errors. Therefore, it is impossible to fundamentally monitor and correct spatial errors that affect machine tool processing accuracy. Therefore, it is of great significance to develop a device and method for measuring the spatial posture errors of machine tool tools. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an on-machine measurement device and method for the spatial posture of a machine tool tool in view of the deficiencies in the above-mentioned prior art, so as to solve the technical problem that the spatial posture error of the tool cannot be directly measured in the machine state.

[0004] The present invention adopts the following technical solutions: A method for measuring the spatial position and posture of a machine tool tool on a machine includes the following steps: Before the machine tool is processed, the frequency modulated continuous wave laser interference system is controlled to emit a beam, and the three target balls installed on the tool handle are scanned by the galvanometer. The beam outlet of the galvanometer is taken as the origin O, and a coordinate system is established to obtain the distance information OA, OB and OC between it and the laser interference system. According to the deflection angle of the galvanometer around the X-axis and Y-axis and , and obtain the three-dimensional coordinates of the three target balls at this position , , ; After the machine tool processing is completed, the frequency modulated continuous wave laser interferometer system is controlled to emit a beam, and the three target balls installed on the tool handle are scanned again by the galvanometer; according to the deflection angle of the galvanometer around the X-axis and Y-axis and , and obtain the three-dimensional coordinates of the three target balls at this position , , ; By comparing the position and posture changes before and after machine tool processing, six spatial posture errors of the tool are obtained respectively, and the error correction of the machine tool system is realized based on the obtained six spatial posture errors of the tool.

[0005] Preferably, before the machine tool is processed, the coordinates of the center point of the triangle formed by the three target balls are , the normal vectors of the three target sphere fitting planes for:

[0006] in, are two vectors that intersect in the fitting plane.

[0007] Preferably, after the machine tool processing is completed, the coordinates of the center point of the triangle formed by the three target balls are , the normal vectors of the three target sphere fitting planes for:

[0008] in, are two vectors that intersect in the fitting plane.

[0009] Preferably, the six spatial posture errors include position error and posture error. The spatial position error of the tool is the distance information of the horizontal displacement along the XYZ axis. ; The spatial posture errors of the tool are respectively the deflection errors around the XYZ axes The spatial position error of the tool is obtained by measuring the center of mass coordinates twice, and the spatial posture error of the tool is obtained by comparing the normal vectors obtained by the two measurements. and Sure.

[0010] Preferably, the distance information Specifically: .

[0012] Preferably, the spatial posture errors of the tool are respectively the deflection errors around the XYZ axes They are:

[0013] in, They are normal vectors and Projection vector on the YOZ plane; They are normal vectors and The projection vector on the XOZ plane, The normal vectors are and Projection vector on the YOX plane.

[0014] Another technical solution of the present invention is an on-machine measuring device for the spatial posture of a machine tool tool, which utilizes the on-machine measuring method for the spatial posture of a machine tool tool, including a calibration module, which is installed on one side of the tool handle of the tool; a frequency modulated continuous wave laser interference system and a galvanometer are installed on the vibration isolation workbench of the machine tool, and the light beam emitted by the frequency modulated continuous wave laser interference system is transformed through the galvanometer to achieve a set angle to cover the calibration module.

[0015] Preferably, the calibration module comprises a target ball tray, on which three target balls are equilaterally distributed, and a spatial positioning algorithm is used to fit the plane where the target balls are located to obtain absolute distance information of the three target balls.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: An on-machine measurement device for the spatial posture of a machine tool tool innovatively applies frequency-modulated continuous-wave laser interferometry and galvanometers to the on-machine measurement and evaluation of the spatial posture error of a CNC machine tool, thereby realizing absolute measurement of the spatial position and posture of the tool, and using a spatial positioning algorithm to fit the plane where the target sphere is located. The deviation between the centroid of the triangle and the normal vector of the fitting plane in the two measurement results before and after processing is used as the spatial posture error of the tool before and after processing by the machine tool, thereby realizing fast and high-precision spatial posture error measurement of the tool, which can meet the measurement and evaluation needs of spatial geometric errors of CNC machine tools.

[0017] Furthermore, since the laser interferometer system is used for non-contact measurement, there will be no mechanical contact interference with the tool or workpiece. This avoids physical deformation, wear or measurement errors that may be caused by contact measurement. In addition, non-contact measurement can also adapt to more complex environments and forms, especially under high temperature, high speed or high vibration conditions.

[0018] Furthermore, by measuring before and after machining, the spatial position change of the tool can be monitored in real time and compared and analyzed. This method can timely detect the possible offset or error of the tool during machining, so as to correct the error and improve the machining accuracy. Especially for complex machining tasks, it can better guarantee the machining quality.

[0019] Furthermore, precise control of the spatial position and posture errors of the tool can help reduce uneven wear or uneven force caused by errors on the tool. This can extend the service life of the tool and maintain the stability of the tool performance during the processing, thereby reducing downtime and reducing maintenance costs; by measuring and compensating the spatial position and posture errors of the tool, the tool's motion trajectory can be planned more accurately to avoid unnecessary offset or inaccurate feeding of the tool during the processing. This not only improves the processing accuracy, but also helps to improve the processing efficiency. The spatial position error of the tool is obtained by the two-measurement method, and the posture error is obtained by normal vector comparison, which can make the error measurement more reliable and accurate. The precise error measurement system can provide more objective data support and help improve the overall processing quality.

[0020] A device for measuring the spatial posture of a machine tool in-machine can emit a stable laser beam, measure the position of a target ball with high precision through interference effect, have very high spatial resolution, and can capture the spatial posture change of the tool at the micron level; the galvanometer changes the direction of the laser beam by precisely controlling its deflection angle around the X-axis and Y-axis, so as to cover the target ball on the calibration module. The high-precision control of the galvanometer enables the laser beam to cover the entire working area of ​​the machine tool tool and obtain comprehensive spatial posture data; it can monitor the spatial posture change of the tool in real time and compare it before and after processing. By measuring the three-dimensional coordinates of the tool before and after processing, the vibration isolation workbench can effectively reduce the influence of external vibration on the measurement results, making the spatial posture measurement of the tool more stable and accurate. The galvanometer and laser interference system work on a stable basis and can eliminate the errors caused by mechanical vibration; it can provide high-precision tool posture measurement, and can monitor and correct errors in real time through automation, thereby improving production efficiency, processing accuracy and product quality. At the same time, the vibration isolation design of the system enhances its stability in complex processing environments, providing effective guarantee for improving machine tool processing accuracy and production efficiency.

[0021] In summary, the present invention has the characteristics of large measurement range, high measurement accuracy, simple structure and low cost, and avoids the drawbacks of the existing method of indirectly calculating the tool position and posture errors through the error model.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings to be used in the description of the embodiments. 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 creative work.

[0024] Figure 1 It is an overall schematic diagram of the measurement scheme of the present invention; Figure 2 It is an exaggerated schematic diagram showing the comparison between the normal vector and the centroid of the fitted plane of the two measurement results; Figure 3 The figure is an exaggerated schematic diagram of the process of solving the three attitude errors, where (a) is the angle between the projection vectors on the YOZ plane, (b) is the angle between the projection vectors on the XOZ plane, and (c) is the angle between the projection vectors on the YOX plane.

[0025] Among them: 1. Target ball; 2. Target ball tray; 3. Frequency modulated continuous wave laser interferometer system; 4. Galvanometer. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0030] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0031] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0032] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0033] See also Figure 1 The present invention discloses an on-machine measuring device for spatial posture of a machine tool, comprising: a target ball 1, a target ball tray 2, a frequency modulated continuous wave laser interference system 3 and a galvanometer 4. The target balls 1 comprise three, and the three target balls 1 are equilaterally distributed on the target ball tray 2, and together with the target ball tray 2, constitute a calibration module, and the calibration module is installed on one side of the tool handle of the tool; the frequency modulated continuous wave laser interference system 3 and the galvanometer 4 are installed on a vibration isolation workbench of the machine tool, and the light beam emitted by the frequency modulated continuous wave laser interference system 3 is transformed through the galvanometer 4 to cover the three target balls 1 in the calibration module, and the absolute distance information of the three target balls 1 is obtained, and the plane where the target balls 1 are located is fitted by a spatial positioning algorithm, and the deviation between the center of mass and the normal vector in the two measurement results before and after processing is obtained, and the deviation is used as the spatial posture error of the tool before and after the machine tool processing, so as to realize fast and high-precision direct measurement of the spatial posture error of the tool.

[0034] A method for measuring the spatial position and posture of a machine tool tool on a machine includes the following steps: S1. Before the machine tool is processed, the light beam emitted by the frequency modulated continuous wave laser interference system 3 is scanned by the galvanometer 4 to scan the target ball 1 on the calibration module and the three target balls installed on the tool handle respectively; the light beam outlet of the galvanometer 4 is taken as the origin O, and a coordinate system is established to obtain the distance information OA, OB and OC between it and the laser interference system; according to the deflection angle of the galvanometer around the X-axis and the Y-axis and , the three-dimensional coordinates of the three target balls at this position can be obtained respectively , , ; See also Figure 2 , fit a plane through three points A, B, and C, and the positions between the three points A, B, and C are relatively fixed and can form a triangle, then the coordinates of the center point (center of mass) of the triangle are In addition, the normal vector of the plane fitted by points A, B, and C is It is obtained by the cross product operation of two vectors:

[0035] in, , .

[0036] S2. After the machine tool processing is completed, the frequency modulated continuous wave laser interference system 3 emits a light beam again, and the three target balls 1 on the calibration module are scanned by the galvanometer, and the three target balls installed on the tool handle are scanned respectively; at this time, the galvanometer also deflects the X-axis and Y-axis according to the deflection angle of the galvanometer. and , and obtain the three-dimensional coordinates of the three target balls at this position , , ; The coordinates of the center point (center of mass) of the triangle formed by points A, B, and C are obtained by solving the coordinates of the center point (center of mass) of the triangle formed by them. ,Depend on , , Normal vector of the plane fitted by the three points It can be obtained by the cross product operation of two vectors:

[0037] in, , .

[0038] S3. By comparing the position and posture changes of the machine tool tool before and after work, the six spatial posture errors of the tool are obtained respectively, providing accurate information for the error correction of the machine tool system to effectively improve the processing accuracy.

[0039] The six spatial posture errors include position error and posture error. The spatial position error of the tool is the distance information of the horizontal displacement along the XYZ axis. ; The spatial posture errors of the tool are respectively the deflection errors around the XYZ axes .

[0040] The spatial position error of the tool is expressed by obtaining the center of mass coordinates through two measurements:

[0041] The spatial posture error of the tool is calculated by comparing the normal vectors obtained from the two measurements. and It is known that, for the convenience of expression, , .

[0042] See also Figure 3 The spatial posture errors of the tool are respectively the deflection errors around the XYZ axes It is expressed as:

[0043] in, They are normal vectors and Projection vector on the YOZ plane; They are normal vectors and The projection vector on the XOZ plane, The normal vectors are and Projection vector on the YOX plane.

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention described and shown in the drawings here can usually be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0045] During the simulation process, numerical simulation tools (such as MATLAB, ANSYS, SolidWorks, etc.) can be used to simulate the behavior of the laser interferometer system and the galvanometer, as well as the spatial motion of the tool in the machine tool. The simulation model is based on the following aspects: The geometric relationship between the machine tool tool and the galvanometer system: By establishing a mathematical model between the machine tool coordinate system and the laser interference system and the galvanometer coordinate system, the process of the laser beam scanning the target ball through the galvanometer is simulated.

[0046] Beam transmission of laser interferometer system: simulate the beam path of laser interferometer system, including the emission, propagation and interference effect of the beam, to ensure that the three-dimensional coordinates of the target sphere position can be accurately measured.

[0047] Control accuracy of the galvanometer: The deflection angle of the galvanometer and its error should be considered in the simulation, which will affect the final measurement results.

[0048] Error analysis: By comparing the changes in the position of the machine tool tool before and after operation, the simulation can calculate the spatial posture error of the machine tool tool and verify the effectiveness of error correction.

[0049]

[0050] By comparing the pose changes obtained from the simulation with the theoretical values, an optimization analysis of the error correction can be performed.

[0051] Example The target ball is mounted on the tool holder, and the laser beam is emitted by the frequency modulated continuous wave laser interferometer system and scanned by the galvanometer. The measured position of the target ball should be recorded at different time points.

[0052] Before measurement: The laser interferometer system scans the target balls on the calibration module through the galvanometer to obtain the three-dimensional coordinates of the three target balls.

[0053] After measurement: After the machine tool processing is completed, the same measurement is performed again to obtain the position of the target ball after processing.

[0054] Data analysis: Compare the three-dimensional coordinate changes between the initial position and the final position, and calculate the posture error.

[0055]

[0056] Spatial posture error: By calculating the coordinate difference of each target ball before and after measurement, the change of the center of mass coordinates and the angular deviation of the normal vector are calculated, and the six spatial posture errors of the machine tool tool (ΔX, ΔY, ΔZ, θ_x, θ_y, θ_z) are obtained. These errors can be used to calibrate the accuracy of the machine tool system, thereby improving the processing accuracy.

[0057]

[0058] Through these experimental data, the spatial error of each target ball is analyzed, thus providing data support for the precision correction of the machine tool.

[0059] By combining simulation and examples, the accuracy and effectiveness of the method of the present invention in measuring the spatial posture of machine tool tools are verified; through error analysis and correction, the machining accuracy of the machine tool system can be significantly improved, providing reliable technical support for actual industrial applications.

[0060] In summary, the present invention provides an on-machine measurement device and method for the spatial posture of a machine tool tool. The absolute distance measurement between a target ball and an interference system can be completed quickly and accurately by using a frequency-modulated continuous wave laser interferometer ranging. The light beam can be adjusted in combination with a galvanometer to obtain the absolute distance information of three target balls. The plane where the target balls are located is fitted with a spatial positioning algorithm to obtain the difference between the normal vector and the center of mass, which is used as the spatial posture error of the tool before and after machine tool processing, thereby realizing fast and high-precision measurement of the spatial posture error of the tool. The frequency-modulated continuous wave laser interferometer ranging and the galvanometer are innovatively applied to the on-machine measurement and evaluation of the spatial posture of CNC machine tool tools, and the spatial posture error of the machine tool tool is directly obtained, thereby avoiding the disadvantage of indirectly calculating the position and direction error of the tool through an error model in the existing method. The device has the characteristics of large measurement range, high measurement accuracy, simple structure and low cost. The embedded system is easy to be integrated into CNC machine tools, and can meet the measurement and evaluation requirements of the spatial geometric errors of machine tool tools.

[0061] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for measuring the spatial posture of a machine tool on a machine, characterized in that: The following steps are involved: Before the machine tool is processed, the frequency modulated continuous wave laser interference system is controlled to emit a beam, and the three target balls installed on the tool handle are scanned by the galvanometer. The beam outlet of the galvanometer is taken as the origin O, and a coordinate system is established to obtain the distance information OA, OB and OC between it and the laser interference system. According to the deflection angle of the galvanometer around the X-axis and Y-axis and , and obtain the three-dimensional coordinates of the three target balls at this position , , ; After the machine tool processing is completed, the frequency modulated continuous wave laser interferometer system is controlled to emit a beam, and the three target balls installed on the tool handle are scanned again by the galvanometer; according to the deflection angle of the galvanometer around the X-axis and Y-axis and , and obtain the three-dimensional coordinates of the three target balls at this position , , ; By comparing the position and posture changes before and after machine tool processing, six spatial posture errors of the tool are obtained respectively, and the error correction of the machine tool system is realized based on the obtained six spatial posture errors of the tool.

2. The on-machine measurement method for the spatial posture of a machine tool according to claim 1, characterized in that: Before the machine tool is processed, the coordinates of the center point of the triangle formed by the three target balls are , the normal vectors of the three target sphere fitting planes for: in, are two vectors that intersect in the fitting plane.

3. The on-machine measurement method for the spatial posture of a machine tool according to claim 1, characterized in that: After the machine tool processing is completed, the coordinates of the center point of the triangle formed by the three target balls are , the normal vectors of the three target sphere fitting planes for: in, are two vectors that intersect in the fitting plane.

4. The on-machine measurement method for the spatial position and posture of a machine tool according to claim 1, characterized in that: The six spatial posture errors include position error and posture error. The spatial position error of the tool is the distance information of the horizontal displacement along the XYZ axis. ; The spatial posture errors of the tool are respectively the deflection errors around the XYZ axes The spatial position error of the tool is obtained by measuring the center of mass coordinates twice, and the spatial posture error of the tool is obtained by comparing the normal vectors obtained by the two measurements. and Sure.

5. The on-machine measurement method for the spatial position and posture of a machine tool according to claim 4, characterized in that: Distance information Specifically: 。 6. The on-machine measurement method for the spatial position and posture of a machine tool according to claim 4, characterized in that: The spatial posture errors of the tool are respectively the deflection errors around the XYZ axes They are: in, They are normal vectors and Projection vector on the YOZ plane; They are normal vectors and The projection vector on the XOZ plane, The normal vectors are and Projection vector onto the YOX plane.

7. An on-machine measuring device for the spatial position of a machine tool, characterized in that: The on-machine measurement method for the spatial posture of a machine tool tool according to any one of claims 1 to 7 is characterized in that it includes a calibration module, which is installed on one side of the tool handle of the tool; a frequency modulated continuous wave laser interferometer system (3) and a galvanometer (4) are installed on the vibration isolation workbench of the machine tool, and the light beam emitted by the frequency modulated continuous wave laser interferometer system (3) is transformed through the galvanometer (4) to achieve a set angle to cover the calibration module.

8. The on-machine measuring device for the spatial position and posture of a machine tool according to claim 7, characterized in that: The calibration module comprises a target ball tray (2), on which three target balls (1) are equilaterally distributed. A spatial positioning algorithm is used to fit the plane where the target balls (1) are located to obtain absolute distance information of the three target balls (1).

9. A computer-readable storage medium storing one or more programs, characterized in that: The one or more programs include instructions, which, when executed by a computing device, cause the computing device to perform the method of any one of claims 1 to 6.

10. A computing device, characterized in that include: One or more processors, a memory and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, and the one or more programs include steps for executing the method described in any one of claims 1 to 6.

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