A machine tool cutter spatial pose on-machine measuring device and a measuring method thereof

Abstract

The application discloses a machine tool cutter space position in-machine measurement device and a measurement method thereof, and comprises a calibration module, which is installed on one side of a tool shank of the cutter; a frequency-modulated continuous wave laser interference system and a vibrating mirror are installed on a vibration isolation workbench of a machine tool; a light beam emitted by the frequency-modulated continuous wave laser interference system is transformed at a set angle through the vibrating mirror to cover the calibration module; a space positioning algorithm is adopted to fit a plane where a target ball is located, and a deviation value between a centroid and a normal vector in two measurement results before and after machining is obtained, which is taken as a cutter space position error before and after machining of the machine tool, so that direct measurement of the cutter space position error is realized quickly and with high precision. The application has the characteristics of large measurement range, high measurement precision, simple structure and low cost, and avoids the disadvantages of indirectly calculating the cutter position and position error through an error model in the prior art.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of numerical control machine tool machining error measurement and compensation, and particularly relates to a machine tool cutter space posture on-machine measurement device and a measurement method thereof. BACKGROUND

[0002] Machine tools are important symbols of measuring the advanced manufacturing level of a country and are widely used in aerospace, aviation, navigation, automobiles, national defense and other fields. The precision index of machine tools is an important embodiment of guaranteeing product quality. The geometric error and thermal error of five-axis numerical control machine tools are one of the main error sources affecting machining precision, accounting for about 60% of the total manufacturing error of machined parts. This is because when the process parameters and the ambient temperature change in the actual machining process, the machine tool dynamic motion error and thermal error value will change, thus directly causing the space posture error of the cutter before and after machining, and thus affecting the manufacturing error of the machined part. Therefore, the measurement and compensation of the space posture error of the machine tool cutter are important means to improve the precision of numerical control machine tools. The spatial error of the comprehensive machining precision of five-axis machine tools is a key factor determining the machining performance. In the existing commonly used machine tool measurement methods, independent instruments (such as laser interferometers, laser trackers, ball bar instruments, etc.) are used for offline measurement. For the spatial error of multiple items such as geometric error and thermal error, there is no effective means to realize on-site in-machine measurement, so it is impossible to fundamentally monitor and correct the spatial error affecting the machining precision of machine tools. Therefore, it is of great significance to develop a machine tool cutter space posture error measurement device and method. SUMMARY

[0003] The technical problem to be solved by the application is to provide a machine tool cutter space posture on-machine measurement device and a measurement method thereof for solving the technical problem that the space posture error of the cutter cannot be directly measured in the on-machine state.

[0004] The application adopts the following technical scheme:

[0005] A machine tool cutter space posture on-machine measurement method comprises the following steps:

[0006] Before machine tool machining, a frequency-modulated continuous wave laser interference system emits a light beam, and three target balls installed on a cutter shank are scanned by a galvanometer respectively; the light beam outlet of the galvanometer is taken as an origin O, and a coordinate system is established to obtain distance information OA, OB and OC of the galvanometer and the laser interference system; according to the deflection angles of the galvanometer around the X axis and the Y axis and , three-dimensional coordinates , , of the three target balls at this position are obtained respectively;

[0007] After the machine tool processing is finished, the control frequency-modulated continuous wave laser interference system sends a light beam, and the three target balls installed on the tool holder are scanned again by the galvanometer respectively and , and three-dimensional coordinates of the three target balls at this position are obtained respectively 、 、 ;

[0008] By comparing the position and attitude changes before and after the machine tool processing, six spatial pose errors of the tool are obtained respectively, and error correction of the machine tool system is realized based on the obtained six spatial pose errors of the tool.

[0009] Preferably, before the machine tool processing, the center point coordinates of the triangle composed of the three target balls are , and the normal vector of the fitting plane of the three target balls is :

[0010]

[0011] wherein are two intersecting vectors in the fitting plane respectively.

[0012] Preferably, after the machine tool processing, the center point coordinates of the triangle composed of the three target balls are , and the normal vector of the fitting plane of the three target balls is :

[0013]

[0014] wherein are two intersecting vectors in the fitting plane respectively.

[0015] Preferably, the six spatial pose errors include position errors and attitude errors, the spatial position errors of the tool are distance information along the XYZ axes respectively; the spatial attitude errors of the tool are deflection errors around the XYZ axes respectively, the spatial position errors of the tool are determined by the centroid coordinates obtained by twice measurement, and the spatial attitude errors of the tool are determined by comparing the normal vectors and obtained by twice measurement.

[0016] Preferably, the distance information is specifically

[0017]

[0018] Preferably, the spatial attitude errors of the tool are deflection errors around the XYZ axes respectively.

[0019]

[0020] wherein, are normal vectors and are projection vectors on the YOZ plane; are normal vectors and are projection vectors on the XOZ plane, are normal vectors and are projection vectors on the YOX plane.

[0021] Another technical solution of the present application is a machine tool cutter space position in-machine measurement device, which utilizes the machine tool cutter space position in-machine measurement method, and comprises a calibration module, which is installed on one side of a tool holder of a cutter.

[0022] Preferably, the calibration module comprises a target ball tray, three target balls are equilateral distributed on the target ball tray, a spatial positioning algorithm is used to fit a plane where the target balls are located, and absolute distance information of the three target balls is obtained.

[0023] Compared with the prior art, the present application has at least the following beneficial effects:

[0024] A machine tool cutter space position in-machine measurement device, which innovatively applies frequency-modulated continuous wave laser interference ranging and a galvanometer to in-machine measurement and evaluation of tool space posture error of a numerical control machine tool, realizes absolute measurement of tool space position and posture, and uses a spatial positioning algorithm to fit a plane where target balls are located, so that a deviation between a centroid of a triangle and a normal vector of the fitted plane in two measurement results before and after machining is taken as tool space posture error before and after machining of the machine tool, realizes fast and high-precision tool space posture error measurement, and can meet the demand of measurement and evaluation of spatial geometric error of the numerical control machine tool.

[0025] Further, since non-contact measurement is performed by using the laser interference system, no mechanical contact interference is caused to the cutter or the workpiece. In this way, physical deformation, wear or measurement error caused by contact measurement is avoided. In addition, non-contact measurement can also adapt to more complex environments and forms, especially in high temperature, high speed or high vibration conditions.

[0026] Further, by measuring before and after machining respectively, the spatial pose change of the tool can be monitored in real time, and comparative analysis can be carried out. This method can timely find the possible deviation or error of the tool in the machining process, so as to correct the error and improve the machining precision. Especially for complex machining tasks, the machining quality can be better guaranteed.

[0027] Further, accurate control of the spatial position and attitude error of the tool can help to reduce the uneven wear or uneven force of the tool caused by error. In this way, the service life of the tool can be prolonged, the stability of the tool performance in the machining process can be maintained, the downtime can be reduced, and the maintenance cost can be reduced; by measuring and compensating the spatial position and attitude error of the tool, the motion trajectory of the tool can be more accurately planned, and unnecessary deviation or inaccurate feeding of the tool in the machining process can be avoided. This not only improves the machining precision, but also helps to improve the machining efficiency. The spatial position error of the tool is obtained by the twice measurement method, and the attitude error is obtained by the normal vector comparison, so that the error measurement is more reliable and accurate. The precise error measurement system can provide more objective data support, and help to improve the overall machining quality.

[0028] A machine tool tool spatial pose in-machine measurement device can emit a stable laser beam, measure the position of the target ball with high precision through interference effect, has very high spatial resolution, and can capture the spatial pose change of the tool at the micron level; the galvanometer changes the direction of the laser beam by accurately controlling the deflection angles thereof around the X axis and the 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 comprehensive spatial pose data is obtained; the spatial pose change of the tool can be monitored in real time, and comparison can be made before and after machining; by measuring the three-dimensional coordinates of the tool before and after machining respectively, the vibration isolation table can effectively reduce the influence of external vibration on the measurement result, so that the spatial pose measurement of the tool is more stable and accurate. The galvanometer and the laser interference system work on a stable basis, and the error caused by mechanical vibration can be eliminated; high-precision tool pose measurement can be provided, and the error can be monitored and corrected in real time in an automatic manner, so as to improve the production efficiency, machining precision and product quality. At the same time, the vibration isolation design of the system enhances its stability in a complex machining environment, and provides effective protection for improving the machining precision of the machine tool and production benefit.

[0029] In summary, the present application has the characteristics of large measurement range, high measurement precision, simple structure and low cost, and avoids the disadvantages of indirectly calculating the tool position and pose error through an error model in the prior art.

[0030] The technical solutions of the present application will be further described in detail below with reference to the drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the accompanying drawings used in the relative embodiment description are briefly introduced as follows. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without any creative effort based on these drawings also belong to the protection scope of the present application.

[0032] Figure 1 The overall schematic diagram of the measurement scheme of the present application;

[0033] Figure 2 The exaggerated schematic diagram of the fitting plane normal vector and the centroid comparison of the two measurement results;

[0034] Figure 3 The exaggerated schematic diagram in the process of solving the three attitude errors, wherein (a) is the included angle between the projected vectors on the YOZ plane, (b) is the included angle between the projected vectors on the XOZ plane, and (c) is the included angle between the projected vectors on the YOX plane.

[0035] Wherein: 1. Target ball; 2. Target ball tray; 3. Frequency-modulated continuous wave laser interference system; 4. Galvanometer. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative effort belong to the protection scope of the present application.

[0037] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "one side", "one end", "one edge" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and thus cannot be understood as indicating or implying that the device or element indicated must have a particular orientation, be constructed and operated in a particular orientation, and thus cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0038] In the description of the application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "linking" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0039] It should be understood that when used in the specification and the appended claims, the terms "comprise" and "include" indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0040] It should also be understood that the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in the specification and the appended claims of the application, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0041] It should be further understood that the term "and / or" used in the specification and the appended claims of the application means any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0042] Various structural diagrams according to the disclosed embodiments of the application are shown in the drawings. These figures are not drawn to scale, in which certain details are exaggerated for the purpose of clear expression, and certain details can be omitted. The shapes of various regions, layers and their relative size and positional relationship shown in the figures are only exemplary, and in actuality there can be deviations due to manufacturing tolerances or technical limitations, and a person skilled in the art can additionally design regions / layers with different shapes, sizes, relative positions according to actual needs.

[0043] Please refer to Figure 1The application discloses a machine tool cutter space position in-machine measurement device, which comprises a target ball 1, a target ball tray 2, a frequency-modulated continuous wave laser interference system 3 and a galvanometer 4. The target ball 1 comprises three target balls which are equilateral distributed on the target ball tray 2 and jointly form a calibration module with the target ball tray 2, and the calibration module is installed on one side of a cutter handle of a cutter. The frequency-modulated continuous wave laser interference system 3 and the galvanometer 4 are installed on a vibration isolation workbench of a machine tool, the light beam emitted by the frequency-modulated continuous wave laser interference system 3 is transformed at a set angle through the galvanometer 4 to cover the three target balls 1 in the calibration module, the absolute distance information of the three target balls 1 is obtained, a space positioning algorithm is adopted to fit the plane where the target ball 1 is located, and the deviation value between the mass center and the normal vector in the measurement results before and after machining is obtained and taken as the cutter space position error before and after machining of the machine tool, so that the direct measurement of the cutter space position error is realized quickly and with high precision.

[0044] A machine tool cutter space position in-machine measurement method, comprising the following steps:

[0045] S1, before machining of the machine tool, the light beam emitted by the frequency-modulated continuous wave laser interference system 3 is scanned on the target ball 1 on the calibration module through the galvanometer 4, and the three target balls installed on the cutter handle are scanned respectively; the light beam outlet of the galvanometer 4 is taken as an origin O, and a coordinate system is established to obtain the distance information OA, OB and OC of the galvanometer 4 and the laser interference system; according to the deflection angles of the galvanometer around the X axis and the Y axis and , the three-dimensional coordinates of the three target balls at the position can be obtained respectively 、 、 ;

[0046] Referring to Figure 2 , a plane is fitted through the points A, B and C, and the positions of the points A, B and C are relatively fixed and can form a triangle, so that the coordinates of the center point (mass center) of the triangle are . In addition, the normal vector of the plane fitted by the points A, B and C is , which is obtained through the cross product operation of two vectors:

[0047]

[0048] Among them, , .

[0049] S2, after machining of the machine tool, the light beam is emitted by the frequency-modulated continuous wave laser interference system 3 again, and the three target balls 1 on the calibration module are scanned through the galvanometer respectively, and the three target balls installed on the cutter handle at this time are scanned respectively; at this time, according to the deflection angles of the galvanometer around the X axis and the Y axis and , the three-dimensional coordinates of the three target balls at the position can be obtained respectively 、 、 ;

[0050] The coordinates of the center point (centroid) of the triangle composed of points A, B and C are obtained by solving the coordinates of the three points , 、 、 The normal vector of the plane fitted by the three points The cross product operation of two vectors can be obtained:

[0051]

[0052] Wherein, , .

[0053] S3, by comparing the position and attitude change of the machine tool cutter before and after work, respectively, the six spatial pose errors of the cutter are obtained, which provides accurate information for error correction of the machine tool system, so as to effectively improve the machining precision.

[0054] The six spatial pose errors include position error and attitude error, wherein the spatial position error of the cutter is the distance information of the transverse movement along the XYZ axis ; The spatial attitude error of the cutter is the deflection error around the XYZ axis .

[0055] The spatial position error of the cutter is represented by the centroid coordinates obtained by two measurements:

[0056]

[0057] The spatial attitude error of the cutter is obtained by comparing the normal vectors and , in order to facilitate expression, let , .

[0058] Please refer to Figure 3 , the spatial attitude error of the cutter is the deflection error around the XYZ axis , which is expressed as:

[0059]

[0060] Wherein, are the projection vectors of the normal vectors and on the YOZ plane, respectively; are the projection vectors of the normal vectors and on the XOZ plane, respectively, the normal vectors are and Projection vector on YOX plane.

[0061] For the purposes of the embodiments of the present application, the technical solutions and advantages, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application.

[0062] During the simulation, numerical simulation tools such as MATLAB, ANSYS, SolidWorks, etc. can be used to simulate the behavior of the laser interference 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:

[0063] Geometric relationship between machine tool and galvanometer system: by establishing the mathematical model between the machine tool coordinate system and the laser interference system, galvanometer coordinate system, the process of laser beam scanning the target ball through the galvanometer is simulated.

[0064] Beam transmission of laser interference system: simulate the beam path of the laser interference system, including the emission, propagation and interference effect of the beam, to ensure accurate measurement of the three-dimensional coordinates of the target ball position.

[0065] Control accuracy of galvanometer: the deflection angle and its error of the galvanometer should be considered in the simulation, which will affect the final measurement results.

[0066] Error analysis: by comparing the position changes before and after the machine tool, the simulation can calculate the spatial pose error of the machine tool, and verify the effectiveness of the error correction.

[0067]

[0068] By comparing the pose changes obtained by simulation with the theoretical values, optimization analysis of error correction can be carried out.

[0069] Embodiment

[0070] Install the target ball on the tool holder and emit laser beams through the frequency-modulated continuous wave laser interference system, using the galvanometer for scanning. The measured position of the target ball should be recorded at different time points.

[0071] Before measurement: The laser interferometer system scans the target balls on the calibration module by galvanometer, obtaining the three-dimensional coordinates of the three target balls.

[0072] After measurement: After the machine tool processing is completed, the same measurement is performed again to obtain the positions of the target balls after processing.

[0073] Data analysis: Compare the three-dimensional coordinate changes of the initial positions and the final positions, and calculate the pose error.

[0074]

[0075] Spatial pose error: By calculating the coordinate differences of each target ball before and after measurement, the changes in centroid coordinates and the angular deviations of normal vectors are calculated to obtain the six spatial pose errors (ΔX, ΔY, ΔZ, θ_x, θ_y, θ_z) of the machine tool cutter. These errors can be used to correct the precision of the machine tool system, thereby improving the processing precision.

[0076]

[0077] Through these experimental data, the spatial error of each target ball is analyzed to provide data support for the precision correction of the machine tool.

[0078] By combining simulation and examples, the accuracy and effectiveness of the method in measuring the spatial pose of the machine tool cutter are verified; through error analysis and correction, the processing precision of the machine tool system can be significantly improved, providing reliable technical support for actual industrial applications.

[0079] In summary, the machine tool cutter spatial pose in-machine measurement device and its measurement method can quickly and accurately complete the absolute distance measurement between the target ball and the interferometer system through frequency-modulated continuous wave laser interferometry, and can realize the adjustment of the light beam to obtain the absolute distance information of the three target balls in combination with the galvanometer. A spatial positioning algorithm is used to fit the plane where the target ball is located to obtain the difference between the normal vector and the centroid, which is used as the spatial pose error of the machine tool cutter before and after processing. The method realizes fast and high-precision measurement of the spatial pose error of the cutter, innovatively applies frequency-modulated continuous wave laser interferometry and galvanometer to the in-machine measurement and evaluation of the spatial attitude of the machine tool cutter, directly obtains the spatial pose error of the machine tool cutter, avoids the drawbacks of indirectly calculating the position and direction error of the cutter through the error model in the existing method, has the characteristics of large measurement range, high measurement precision, simple structure, low cost, and is easy to integrate into the numerical control machine tool, and can meet the demand of machine tool cutter spatial geometric error measurement and evaluation.

[0080] The above content only illustrates the technical idea of the present application and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solution falls within the protection scope of the claims of the present application.

Claims

1. A method for on-machine measurement of the spatial pose of a machine tool cutting tool, characterized in that, Includes the following steps: Before the machine tool begins machining, the frequency-modulated continuous wave laser interferometer system emits a beam, which is then scanned by a galvanometer to three target spheres mounted on the tool holder. A coordinate system is established with the beam exit of the galvanometer as the origin O, and the distances OA, OB, and OC between the target spheres and the laser interferometer system are obtained. Based on the galvanometer's deflection angles around the X and Y axes... and The three-dimensional coordinates of the three target balls at this position were obtained respectively. , , Before the machine tool begins machining, the coordinates of the center point of the triangle formed by the three target spheres are: The normal vectors of the fitting plane of the three target spheres for: in, These are two intersecting vectors in the fitting plane; After the machine tool finishes machining, the frequency-modulated continuous wave laser interferometer system emits a beam, which is then scanned again by a galvanometer on the three target spheres mounted on the tool holder. The beam is then adjusted according to the galvanometer's deflection angles around the X and Y axes. and The three-dimensional coordinates of the three target balls at this position were obtained respectively. , , After the machine tool finishes machining, the coordinates of the center point of the triangle formed by the three target spheres are: The normal vectors of the fitting plane of the three target spheres for: in, These are two intersecting vectors in the fitting plane; By comparing the changes in position and orientation before and after machining, six spatial pose errors of the tool are obtained. Based on these six spatial pose errors, error correction of the machine tool system is implemented. These six spatial pose errors include position error and orientation error. The spatial position error of the tool is defined as the distance traveled laterally along the XYZ axes. The spatial attitude errors of the tool are respectively the deflection errors around the XYZ axes. The spatial position error of the tool was obtained by measuring the centroid coordinates twice, and the spatial attitude error of the tool was obtained by comparing the normal vectors obtained from the two measurements. and Sure.

2. The method for on-machine measurement of the spatial pose of a machine tool according to claim 1, characterized in that, Distance information Specifically: 。 3. The method for on-machine measurement of the spatial pose of a machine tool according to claim 1, characterized in that, The spatial attitude errors of the tool are respectively the deflection errors around the XYZ axes. They are respectively: in, Normal vectors and The projection vector on the YOZ plane; Normal vectors and The projection vector on the XOZ plane. The normal vectors are respectively and The projection vector onto the YOX plane.

4. An on-machine measurement device for the spatial pose of a machine tool cutting tool, characterized in that, The machine tool spatial pose measurement method according to claim 1, 2 or 3 is characterized in that it includes a calibration module, which is installed on one side of the tool holder; a frequency-modulated continuous wave laser interferometer (3) and a galvanometer (4) are installed on the vibration isolation worktable of the machine tool, and the beam emitted by the frequency-modulated continuous wave laser interferometer (3) is transformed by the galvanometer (4) to cover the calibration module.

5. The machine tool tool spatial pose measurement device according to claim 4, characterized in that, The calibration module includes 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 the absolute distance information of the three target balls (1).

6. A computer-readable storage medium for storing one or more programs, characterized in that, The one or more programs include instructions that, when executed by a computing device, cause the computing device to perform the method of claim 1, 2, or 3.

7. 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, the one or more programs including steps for performing the method of claim 1, 2, or 3.

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