Numerical control machine tool space and thermal error synchronous detection device, system and method

Abstract

The invention discloses a numerical control machine tool space and thermal error synchronous detection device, system and method, and relates to the field of machine tool error detection. Comprising a substrate; a zero point positioning system; the standard ball measuring tools are arranged along the S-shaped curve and the heights of the standard ball measuring tools are increased progressively; the measuring head assembly comprises a cutter handle and a measuring head body installed at the end of the cutter handle, three displacement sensors are evenly distributed on the measuring head body along the circumference, and the axes of the three sensors are mutually orthogonal and point to the center of the measuring head body; the time-sharing driving control unit is used for controlling the three sensors to start sampling in sequence; and the upper computer is used for receiving the sampling data and performing spatial coupling analysis. According to the invention, the whole working space is covered through S-shaped space progressive increase layout, electromagnetic interference of multiple sensors is avoided by adopting time-sharing driving, rapid high-precision repeated clamping is realized by utilizing a zero point positioning system, and synchronous decoupling of space errors and thermal errors is realized through cold-state / hot-state repeated measurement.

Description

Technical Field

[0001] This invention relates to the field of machine tool error detection technology, specifically to a device, system, and method for synchronously detecting spatial and thermal errors in CNC machine tools. Background Technology

[0002] Five-axis CNC machine tools are core equipment in modern manufacturing, and their machining accuracy directly affects product quality. Among the many error sources affecting machine tool machining accuracy, spatial errors caused by machine tool geometric defects and thermal errors caused by heat source changes are the main factors. Thermal errors can account for 40% to 70% of the total error under certain precision machining conditions. Although thermal error compensation technology is widely used, its effective implementation requires efficient and accurate measurement of both spatial and thermal errors.

[0003] Currently widely used machine tool error detection devices, such as laser interferometers and ballbars, have inherent drawbacks: laser interferometers are expensive, complex to install and debug, and time-consuming to measure, and a single measurement cannot cover the entire working space and temperature range; while ballbars are relatively quick to install, they mainly perform two-dimensional planar circular trajectory tests, making it difficult to comprehensively characterize three-dimensional spatial errors, and they cannot simultaneously measure thermal errors. Existing technologies cannot simultaneously obtain the spatial and thermal errors of a machine tool during a single clamping and measurement process. Multiple measurements are not only inefficient, but the measurement data cannot truly reflect the actual "geometry-thermal coupling" working conditions.

[0004] Therefore, there is an urgent need in this field for an error detection scheme that can simultaneously measure spatial error and thermal error, in order to overcome the shortcomings of existing technologies such as cumbersome installation, low measurement efficiency, and difficulty in simultaneously measuring spatial error and thermal error. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a device, system and method for synchronous detection of spatial and thermal errors in CNC machine tools. Through the combined design of S-shaped spatial layout, three-sensor time-sharing drive and zero-point positioning system, it realizes the measurement of the entire working space in one clamping and the synchronous decoupling of spatial error and thermal error.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a device for synchronous detection of spatial and thermal errors in CNC machine tools, comprising: A substrate; a zero-point positioning system, including multiple zero-point positioner females fixed on the substrate; multiple standard ball gauges, each with a positioning pull stud integrated at its bottom that mates with the zero-point positioner females, the multiple standard ball gauges arranged along an S-shaped curve on the substrate and having increasing heights in a direction perpendicular to the substrate; a probe assembly, including a tool holder and a probe mounted on the end of the tool holder, the probe having three displacement sensors evenly distributed along its circumference, the axes of the three displacement sensors being orthogonal to each other and pointing towards the center of the probe; a time-division drive control unit, used to control the three displacement sensors to sequentially start sampling at each measurement position to avoid electromagnetic interference; a host computer, used to receive the sampling data from the displacement sensors and perform spatial coupling analysis to calculate the displacement difference between the center of the probe and the center of the standard ball.

[0008] Furthermore, the repeatability of the zero-point positioning system is ≤2μm, the tension of a single positioning rivet is ≥10kN, and the zero-point positioner female seat and the positioning rivet adopt a short cone fit structure or a steel ball locking structure.

[0009] Furthermore, the standard ball gauge includes a standard ball, a ball rod, and the positioning pull pin. The standard ball is threadedly connected to the ball rod, the ball rod is threadedly connected to the positioning pull pin, and the connection between the ball rod and the positioning pull pin is provided with a stop positioning structure or a cylindrical pin positioning structure.

[0010] Furthermore, the displacement sensor is an eddy current displacement sensor with linearity ≤ ±0.1%FS, resolution ≤ 0.05%FS, and a range of 0.5mm-2mm.

[0011] Furthermore, the time-sharing drive control unit includes a high-frequency switching circuit, which controls the three displacement sensors to sequentially complete single-channel sampling within a microsecond time.

[0012] Secondly, the present invention provides a CNC machine tool spatial and thermal error synchronous detection system, including the CNC machine tool spatial and thermal error synchronous detection device as described above, as well as a measurement path control module and an error decoupling module; the measurement path control module is used to control the machine tool spindle to drive the probe assembly to sequentially pass through each standard ball gauge along the S-shaped machining program for measurement; the error decoupling module is used to execute the first measurement program in the cold state of the machine tool to obtain the reference spatial error, and to repeatedly execute the measurement program in different thermal states after the machine tool is running and heating up to obtain the comprehensive spatial error of coupled thermal error, and to identify the time-varying thermal error through data comparison and separation algorithm, thereby realizing the synchronous decoupling of spatial error and thermal error.

[0013] Furthermore, the error decoupling module specifically includes: a machine tool kinematic chain modeling unit, used to establish a kinematic chain based on the machine tool structure and clarify the error transmission path; an error element analysis unit, used to clarify geometric error elements and thermal error elements; a comprehensive error model construction unit, used to establish a comprehensive error mathematical model based on forward kinematics operations and homogeneous coordinate transformation matrices; and an error separation unit, used to separate pure spatial error and pure thermal error by performing decoupling calculations with the comprehensive error mathematical model based on the time-invariant characteristics of spatial error and the time-varying characteristics of thermal error through repeated measurement data.

[0014] Thirdly, the present invention provides a method for synchronous detection of spatial and thermal errors in CNC machine tools, applied to the aforementioned synchronous detection device or system for spatial and thermal errors in CNC machine tools, comprising the following steps: S1. Multiple standard ball gauges are mounted on the base plate along an S-shaped curve with increasing height using a zero-point positioning system; S2. Install the probe assembly on the machine tool spindle, and calibrate the installation eccentricity of the three displacement sensors by the spindle rotation self-calibration method to generate a calibration matrix; S3. When the machine tool is cold, the spindle is controlled to drive the probe assembly to pass through each standard ball gauge in sequence along the S-shaped machining program. The three displacement sensors are controlled by the time-sharing drive control unit to start sampling in sequence at each measurement position to obtain the ball center coordinates of each standard ball gauge as reference data. S4. Run the machine tool to the heating state, repeat step S3, and obtain the center coordinate data of each standard ball gauge under different heating states; S5. Based on the data obtained in steps S3 and S4, and combined with the comprehensive error mathematical model, spatial error and thermal error are separated.

[0015] Further, the spindle rotation self-calibration method described in step S2 includes: aligning the probe assembly with any standard spherical gauge and keeping the coordinates fixed, controlling the spindle to rotate 360 ​​degrees; recording the waveform data of the readings of the three displacement sensors as the rotation angle changes; performing least-squares circle fitting on the waveform data to calculate the eccentricity and phase deviation between the actual rotation center of the probe and the sensing surface of each displacement sensor; and generating a calibration matrix based on the calculation results to automatically deduct installation errors in subsequent measurements.

[0016] Furthermore, the mathematical model for the comprehensive error described in step S5 is as follows:

[0017] in, This represents the overall error at temperature T. For spatial error, The coefficient of thermal distortion, This refers to the change in temperature. By solving the system of cold-state measurement data and at least two different hot-state measurement data, we obtain... and This achieves decoupling of spatial error and thermal error.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention can complete the error measurement of the entire working space with a single clamping. Combined with repeated cold / hot state measurements, it achieves synchronous measurement and decoupling of spatial error and thermal error, improving the measurement efficiency by more than 90% compared with traditional methods.

[0019] 2. The present invention adopts an S-shaped spatial incremental layout to simulate the real machining trajectory, which can fully stimulate the dynamic error of the machine tool when multiple axes are linked, and the measurement results are closer to the actual machining conditions.

[0020] 3. The zero-point positioning system used in this invention enables rapid and high-precision repeated clamping of standard ball gauges without the need for repeated manual calibration, which greatly shortens the measurement preparation time, reduces the dependence on the operator's skills, and significantly improves the overall measurement efficiency.

[0021] 4. Compared to expensive laser interferometer systems, the device of this invention has a simpler structure and lower manufacturing and maintenance costs. Furthermore, the time-sharing drive strategy of the three displacement sensors physically cuts off the source of electromagnetic field superposition, effectively eliminating mutual interference when multiple sensors are densely arranged, thus ensuring measurement accuracy. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of the CNC machine tool spatial and thermal error synchronous detection device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the tool holder structure with a displacement sensor probe in an embodiment of the present invention; Figure 3 This is a schematic diagram showing the positional relationship between the sensor and the standard ball in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the error value measurement principle in an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the standard ball measuring tool in an embodiment of the present invention; Figure 6 This is a schematic diagram comparing the height of the standard ball gauge in an embodiment of the present invention; Figure 7 This is a schematic diagram showing the angle between the probe and the standard ball in an embodiment of the present invention; Figure 8 This is a schematic diagram of the measurement path of the probe in an embodiment of the present invention.

[0024] In the figure: 1-base plate, 2-standard ball gauge, 21-standard ball, 22-ball rod, 23-positioning pull stud, 3-zero point positioner female seat, 4-tool handle, 41-probe, 42-displacement sensor, 10-probe center, 20-standard ball center. Detailed Implementation

[0025] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0026] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Example 1 like Figure 1-5 As shown, this embodiment provides a CNC machine tool spatial and thermal error synchronous detection device, including a base plate 1, a zero-point positioning system, multiple standard ball gauges 2, a probe assembly, a time-sharing drive control unit, and a host computer.

[0028] The zero-point positioning system includes multiple zero-point locator female seats 3 fixed on the base plate 1. Each standard ball gauge 2 has a positioning pull stud 23 integrated at its bottom that mates with the zero-point locator female seat 3. The zero-point positioning system employs a precision short-cone fit structure conforming to EROWA or SYSTEM 3R standards, with a repeatability accuracy ≤2μm, ensuring that the reference position does not shift after the standard ball is assembled or disassembled, guaranteeing measurement consistency. The tension force of a single positioning pull stud is ≥10kN, ensuring connection rigidity and preventing micro-movements during measurement. Exemplarily, the interface between the zero-point locator female seat and the positioning pull stud uses a short-cone fit structure or a steel ball locking structure. As a preferred example, the short-cone fit structure can use a 1:10 taper, which has a self-centering function, ensuring that the axis of the standard ball gauge precisely coincides with the reference position on the base plate during each clamping. The steel ball locking structure provides a stable tension force, preventing micro-displacement during measurement.

[0029] like Figure 5 As shown, each standard ball gauge includes a standard ball 21, a ball rod 22, and a positioning pull pin 23. The standard ball is made of tungsten carbide or ceramic, possessing high hardness and a low coefficient of thermal expansion, enabling it to maintain shape accuracy over a long period. The ball rod is made of stainless steel, providing good rigidity and corrosion resistance. The standard ball 21 is threaded to the ball rod 22, and the ball rod 22 is threaded to the positioning pull pin 23. The connection between the ball rod 22 and the positioning pull pin 23 is equipped with a stop positioning structure or a cylindrical pin positioning structure. The stop positioning structure ensures the coaxiality of the ball rod axis and the pull pin axis. In this embodiment, the coaxiality is controlled within 0.005 mm, thereby ensuring the consistency of the geometric center of the standard ball gauge with the positioning datum.

[0030] like Figure 1 and Figure 6 As shown, multiple standard ball gauges are arranged along an S-curve on the base plate, with increasing heights in the direction perpendicular to the base plate. The shape of the S-curve is based on the shape of the S-shaped specimen in ISO 10791-7:1998. This layout can cover the entire working space of the machine tool's XY plane. The height difference in the Z-direction between the standard ball gauges is achieved by replacing ball rods of different lengths. The height difference value can be set to increase equidistantly according to the machine tool's Z-axis travel, thus covering the complete error space in the Z-axis direction. The core function of this layout design is that the S-curve simulates the machining trajectory of typical complex curved surface parts, which can fully stimulate the dynamic error of the machine tool in multi-axis linkage; the Z-direction increasing layout allows spatial error data at different height positions to be obtained in a single measurement without repeated clamping or adjustment.

[0031] like Figure 2 As shown, the probe assembly includes a tool holder 4 and a probe 41 mounted on the end of the tool holder. The tool holder uses a standard BT or HSK interface, enabling quick connection to the machine tool spindle. Three displacement sensors 42 are evenly distributed along the circumference of the probe 41. The axes of the three displacement sensors 42 are mutually orthogonal and point towards the center of the probe 41. This design allows the three orthogonally arranged displacement sensors 42 to simultaneously sense the relative displacement components of the standard ball 21 in three orthogonal directions (X, Y, Z) when the probe 41 contacts or approaches the standard ball 21. If the displacement sensor axes do not point towards the center, the measured value will include systematic errors caused by the eccentric installation of the displacement sensors; if the displacement sensors are not mutually orthogonal, the displacement components in the three directions will be coupled, making it impossible to directly calculate the three-dimensional coordinates of the ball's center. Therefore, this structural design is the geometric basis for achieving accurate three-dimensional spatial position measurement.

[0032] like Figure 3As shown, the positional relationship between the displacement sensor 42 and the standard sphere 21 illustrates the relative geometric relationship during the measurement process. In this embodiment, the displacement sensor is an eddy current displacement sensor, with a linearity ≤ ±0.1%FS, a resolution ≤ 0.05%FS, and a measurement range of 0.5mm-2mm. The eddy current displacement sensor is a non-contact measurement device, which will not cause wear on the surface of the standard sphere 21; it has a fast response speed and can meet the requirements of high-speed measurement.

[0033] The time-sharing drive control unit includes a high-frequency switching circuit for controlling three displacement sensors to sequentially start sampling at each measurement position to avoid electromagnetic interference. In this embodiment, the high-frequency switching circuit controls the three sensors to complete single-channel sampling sequentially within microseconds. For example, the single-channel sampling time is 50μs, the switching interval is 10μs, and the time to complete a set of data acquisition is less than 200μs; the sampling time and switching time can be set according to specific requirements, and this embodiment is not limited to this. Specifically, the device described in this embodiment adopts a time-sharing drive control strategy. At each detection position, the high-frequency switching circuit controls the three displacement sensors to start sequentially: displacement sensor A starts sampling at time T1, displacement sensor B starts sampling at time T2, and displacement sensor C starts sampling at time T3. The sampling time of each displacement sensor and the switching interval of the displacement sensors are as described above, completing a set of sampling (three channels A, B, and C).

[0034] The working principle of this time-division driving strategy is based on a clear physical mechanism: eddy current displacement sensors rely on alternating magnetic fields to operate. When three displacement sensors are closely arranged, if they are energized simultaneously, the magnetic fields will superimpose, generating crosstalk and leading to a decrease in measurement accuracy. With the time-division driving strategy, at any given time T, only one displacement sensor coil is energized, while the other two are either off or in a high-impedance state. This physically cuts off the source of magnetic field superposition, thus theoretically eliminating mutual interference completely. Compared to conventional synchronous driving methods, the signal-to-noise ratio improvement of this scheme depends on the inherent noise floor of a single sensor, rather than interference noise, significantly improving measurement accuracy.

[0035] The host computer receives the sampling data from the displacement sensors and performs spatial coupling analysis to calculate the displacement difference between the probe center (i.e., the intersection point of the three displacement sensor axes) and the center of the standard sphere. For example... Figure 4As shown in the diagram, the error measurement schematic illustrates the positional deviation between the probe center 10 and the standard sphere center 20. The host computer, through coordinate system transformation and spatial geometric calculations, synthesizes the displacement measurements from the three displacement sensors into a three-dimensional sphere center deviation vector. Specifically, after the three displacement sensors complete their independent measurements, the host computer performs spatial coupling analysis on the three sets of data received. In this way, the positional difference between the probe center 10 and the standard sphere center 20 is calculated, which is the spatial and thermal coupling error. By repeatedly measuring under different temperature conditions, the two can be separated.

[0036] Example 2 This embodiment provides a CNC machine tool spatial and thermal error synchronous detection system, including the device described in Embodiment 1, as well as a measurement path control module and an error decoupling module.

[0037] The measurement path control module controls the machine tool spindle to drive the probe assembly along the S-shaped machining program, sequentially passing through each standard ball gauge for measurement. For example... Figure 7 The diagram shows the angle between the probe 41 and the standard sphere 21. The line connecting the probe axis and the center of the standard sphere forms a 45-degree angle. This angle setting helps the displacement sensor maintain its optimal linear operating range during measurement. Figure 8 The diagram shows the measurement path of the probe. Probe 41 measures along paths 1-7 in the diagram: first, it circles the standard sphere once (path 1-4) to obtain the sphere's contour information in the horizontal plane; then, it moves back and forth along the X direction once (path 5-6) to obtain the sphere's center offset data in the X direction; finally, it moves once along the Y direction (path 7) to obtain the sphere's center offset data in the Y direction. This path design can acquire complete three-dimensional information of the standard sphere's center within a limited time.

[0038] The error decoupling module is used to execute the first measurement program when the machine tool is cold to obtain the reference spatial error. The measurement program is repeatedly executed under different thermal states after the machine tool is running and heating up to obtain the comprehensive spatial error of coupled thermal error. The time-varying thermal error is identified through data comparison and separation algorithms, thereby achieving synchronous decoupling of spatial error and thermal error.

[0039] The error decoupling module specifically includes: Machine tool kinematic chain modeling unit: Based on the machine tool structure, the kinematic chain is established to clarify the error transmission path between the tool and the workpiece. For a five-axis CNC machine tool, the kinematic chain includes a series combination of linear axes (X, Y, Z) and rotary axes.

[0040] Error Element Analysis Unit: Identifies geometric error elements and thermal error elements. Geometric errors include positioning errors, straightness errors, and angular errors of each motion axis; thermal errors include thermal deformation displacement and thermal deformation angle of each motion axis due to temperature changes.

[0041] The comprehensive error model construction unit establishes a comprehensive error mathematical model based on forward kinematics operations and a homogeneous coordinate transformation matrix. Ideally, the position of the tool center point in the working coordinate system can be obtained through homogeneous transformation of the theoretical displacements of each motion axis. In reality, the actual poses of each motion axis deviate from the theoretical values, and these deviations are introduced into the kinematic chain through the error transformation matrix. Ignoring infinitesimals of second order and above, the influence of each error source is linearly superimposed to obtain the comprehensive error mathematical model.

[0042] Error separation unit: Based on the time-invariant characteristics of spatial error and the time-varying characteristics of thermal error, the pure spatial error and the pure thermal error are separated by decoupling calculation through repeated measurement data and comprehensive error mathematical model.

[0043] Example 3 This embodiment provides a method for synchronously detecting spatial and thermal errors in CNC machine tools, using the device described in Embodiment 1 or the system described in Embodiment 2, including the following steps: S1. Install standard ball gauge Multiple standard ball gauges are mounted on a base plate along an S-shaped curve with increasing height using a zero-point positioning system. The specific operation is as follows: First, fix the base plate to the machine tool table. Align the positioning pins of each standard ball gauge with the zero-point locator female on the base plate. Utilize the self-centering function of the short cone to automatically center the standard ball gauges. Apply a tension force of ≥10kN through the steel ball locking mechanism to ensure connection rigidity. After installation, the standard ball gauges are distributed in an S-shape in the XY plane and increase in height in the Z direction, forming a three-dimensional measurement array covering the entire working space of the machine tool.

[0044] S2, Calibration sensor installation misalignment The probe assembly is mounted on the machine tool spindle, and the mounting eccentricity of the three displacement sensors is calibrated using the spindle rotation self-calibration method to generate a calibration matrix. Specific steps include: Align the probe assembly with any standard ball gauge, keep the coordinates stationary, and control the spindle to rotate 360 ​​degrees. Record the waveform data of the readings of the three displacement sensors as the rotation angle changes; The waveform data is fitted with least squares circle to calculate the eccentricity and phase deviation between the actual rotation center of the probe and the sensing surface of each sensor. A calibration matrix is ​​generated based on the calculation results, which is used to automatically deduct installation errors in subsequent measurements.

[0045] This self-calibration method does not rely on high-precision machining to ensure the absolute installation position of the sensor. Instead, it compensates for installation errors through algorithms, which greatly reduces the manufacturing difficulty and assembly requirements of the device.

[0046] S3, Cold State Measurement With the machine tool in a cold state, the control spindle drives the probe assembly along an S-shaped machining program, sequentially passing through each standard spherical gauge. A time-sharing drive control unit controls three displacement sensors to sequentially activate sampling at each measurement position, acquiring the center coordinates of each standard spherical gauge as reference data. In this step, the trajectory of the S-shaped machining program matches the S-shaped layout of the standard spherical gauges, ensuring that the probe sequentially passes through each measurement point.

[0047] S4, Thermal Measurement Run the machine tool until it reaches a heated state, and repeat step S3 to obtain the center coordinate data of each standard spherical gauge under different heated states. In this embodiment, multiple heated state measurement points can be set, for example, measurements can be taken after the machine tool has been running for 30 minutes, 60 minutes, and 120 minutes, to obtain dynamic data on the change of thermal error with temperature.

[0048] S5, Error Separation Based on the data obtained in steps S3 and S4, and combined with the comprehensive error mathematical model, spatial error and thermal error are separated.

[0049] The process of establishing the comprehensive error mathematical model is as follows: The kinematic chain is established based on the machine tool structure, and the pose of the tool relative to the workpiece is described by the homogeneous coordinate transformation matrix. Ignoring infinitesimals of order two and above, the comprehensive error mathematical model is established as follows:

[0050] in, This represents the overall error at temperature T. For spatial error, This represents the thermal error at temperature T. Based on the time-invariant properties of spatial error and the time-varying properties of thermal error, the thermal error is expressed as... ,in The coefficient of thermal distortion, If the change in temperature is taken as the mathematical model for the overall error, then:

[0051] Through cold state measurement data ( )get Then, by simultaneously solving the system of at least two different thermal measurement data, we can obtain... and This achieves decoupling of spatial error and thermal error.

[0052] The device, system, and method proposed in this invention achieve full workspace coverage through an S-shaped incremental spatial layout. Combined with a time-sharing drive control strategy, it effectively suppresses electromagnetic interference between multiple sensors and utilizes a zero-point positioning system for rapid, high-precision, and repeatable clamping. Furthermore, through repeated cold and hot state measurements and an error decoupling algorithm, it can simultaneously acquire the machine tool's spatial and thermal errors under a single clamping condition. Compared with existing technologies, this solution is expected to have significant advantages in measurement efficiency, realism of working condition simulation, and ease of operation, making it suitable for widespread application in workshop environments.

[0053] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the embodiments of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A device for synchronously detecting spatial and thermal errors in CNC machine tools, characterized in that, include: substrate; The zero-point positioning system includes multiple zero-point positioner females fixed on the substrate; Multiple standard ball gauges, each with a positioning rivet integrated at its bottom that mates with the zero-point locator base, the multiple standard ball gauges arranged along an S-shaped curve on the base plate and having increasing height in a direction perpendicular to the base plate; The probe assembly includes a tool holder and a probe mounted on the end of the tool holder. Three displacement sensors are evenly distributed along the circumference of the probe, and the axes of the three displacement sensors are orthogonal to each other and point towards the center of the probe. The time-sharing drive control unit is used to control the three displacement sensors to sequentially start sampling at each measurement position in order to avoid electromagnetic interference. The host computer is used to receive the sampling data from the displacement sensor and perform spatial coupling analysis to calculate the displacement difference between the center of the probe and the center of the standard ball.

2. The CNC machine tool spatial and thermal error synchronous detection device according to claim 1, characterized in that, The repeatability of the zero-point positioning system is ≤2μm, the tension of a single positioning rivet is ≥10kN, and the zero-point positioner female seat and the positioning rivet adopt a short cone fit structure or a steel ball locking structure.

3. The CNC machine tool spatial and thermal error synchronous detection device according to claim 1, characterized in that, The standard ball gauge includes a standard ball, a ball rod, and the positioning pull pin. The standard ball is threadedly connected to the ball rod, and the ball rod is threadedly connected to the positioning pull pin. The connection between the ball rod and the positioning pull pin is provided with a stop positioning structure or a cylindrical pin positioning structure.

4. The CNC machine tool spatial and thermal error synchronous detection device according to claim 1, characterized in that, The displacement sensor is an eddy current displacement sensor with linearity ≤ ±0.1%FS, resolution ≤ 0.05%FS, and a range of 0.5mm-2mm.

5. The CNC machine tool spatial and thermal error synchronous detection device according to claim 1, characterized in that, The time-sharing drive control unit includes a high-frequency switching circuit, which controls the three displacement sensors to sequentially complete single-channel sampling within a microsecond time.

6. A synchronous detection system for spatial and thermal errors in CNC machine tools, characterized in that, include: The CNC machine tool spatial and thermal error synchronous detection device as described in any one of claims 1-5; as well as The measurement path control module is used to control the machine tool spindle to drive the probe assembly to sequentially pass through each standard ball gauge along the S-shaped machining program for measurement; The error decoupling module is used to execute the first measurement program when the machine tool is cold to obtain the reference spatial error, and to repeatedly execute the measurement program under different thermal states after the machine tool is running and heating up to obtain the comprehensive spatial error of coupled thermal error. It also identifies the time-varying thermal error through data comparison and separation algorithms, thereby achieving synchronous decoupling of spatial error and thermal error.

7. The CNC machine tool spatial and thermal error synchronous detection system according to claim 6, characterized in that, The error decoupling module specifically includes: The machine tool kinematic chain modeling unit is used to establish kinematic chains based on the machine tool structure and define error propagation paths. Error element analysis unit, used to identify geometric error elements and thermal error elements; The integrated error model construction unit is used to establish a comprehensive error mathematical model based on forward kinematics operations and homogeneous coordinate transformation matrices. The error separation unit is used to separate pure spatial error and pure thermal error by decoupling the calculations from the comprehensive error mathematical model based on the time-invariant characteristics of spatial error and the time-varying characteristics of thermal error through repeated measurement data.

8. A method for synchronously detecting spatial and thermal errors in a CNC machine tool, applied to the device as described in any one of claims 1-5 or the system as described in any one of claims 6-7, characterized in that, Includes the following steps: S1. Multiple standard ball gauges are mounted on the base plate along an S-shaped curve with increasing height using a zero-point positioning system; S2. Install the probe assembly on the machine tool spindle, and calibrate the installation eccentricity of the three displacement sensors by the spindle rotation self-calibration method to generate a calibration matrix; S3. When the machine tool is cold, the spindle is controlled to drive the probe assembly to pass through each standard ball gauge in sequence along the S-shaped machining program. The three displacement sensors are controlled by the time-sharing drive control unit to start sampling in sequence at each measurement position to obtain the ball center coordinates of each standard ball gauge as reference data. S4. Run the machine tool to the heating state, repeat step S3, and obtain the center coordinate data of each standard ball gauge under different heating states; S5. Based on the data obtained in steps S3 and S4, and combined with the comprehensive error mathematical model, spatial error and thermal error are separated.

9. The method for synchronous detection of spatial and thermal errors in CNC machine tools according to claim 8, characterized in that, The spindle rotation self-calibration method described in step S2 includes: Align the probe assembly with any standard ball gauge and keep the coordinates stationary while controlling the spindle to rotate 360 ​​degrees. Record the waveform data of the readings of the three displacement sensors as the rotation angle changes; The waveform data is fitted with least squares circle to calculate the eccentricity and phase deviation between the actual rotation center of the probe and the sensing surface of each displacement sensor. A calibration matrix is ​​generated based on the calculation results, which is used to automatically deduct installation errors in subsequent measurements.

10. The method for synchronous detection of spatial and thermal errors in CNC machine tools according to claim 8, characterized in that, The mathematical model for the comprehensive error described in step S5 is as follows: in, This represents the overall error at temperature T. For spatial error, The coefficient of thermal distortion, This refers to the change in temperature. By solving the system of cold-state measurement data and at least two different hot-state measurement data, we obtain... and This achieves decoupling of spatial error and thermal error.

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