Numerical control machine tool space positioning thermal error compensation method and five-axis machine tool

Abstract

The present application relates to five-axis machine tool control technical field, specifically relates to a kind of numerical control machine tool space positioning thermal error compensation method and five-axis machine tool, comprising: the positioning accuracy thermal error model containing temperature term dependent variable is respectively constructed to each movement axis of the machine tool to be compensated;Actual positioning error is measured to the machine tool to be compensated, and positioning accuracy thermal error model is optimized according to actual positioning error and obtains optimization model;Optimization model is used to compensate the space positioning process of the machine tool to be compensated.For the problem that the overall machining accuracy is limited in the prior art due to the lack of compensation for the positioning error of the machine tool, the positioning accuracy thermal error model containing temperature term dependent variable is respectively constructed before positioning for each movement axis, so that the geometric error and thermal error are unified during positioning, and the positioning deviation caused by geometric error and thermal error during machine tool positioning can be effectively compensated, and the machining accuracy of the machine tool is improved.

Description

Technical Field

[0001] This invention relates to the field of five-axis machine tool control technology, specifically to a method for compensating for thermal errors in spatial positioning of CNC machine tools and a five-axis machine tool. Background Technology

[0002] CNC machine tools, short for Computer Numerical Control machine tools, are automated machine tools equipped with a program control system. This control system logically processes programs with control codes or other symbolic instructions, decodes them, represents them with coded numbers, and inputs them into the CNC device via an information carrier. After processing, the CNC device sends various control signals to control the machine tool's movements, automatically machining parts according to the shape and dimensions required by the drawings. To achieve good machining accuracy, the errors generated by each axis of the CNC machine tool during movement must be considered. Generally, these errors mainly include geometric errors generated by the movement of the machine tool's moving parts, and thermal errors introduced by the thermal expansion of the parts during machining.

[0003] In the existing technology, there are already some methods for compensating for geometric errors and thermal errors in machine tools during the motion process.

[0004] For example, Chinese patent CN201610159196.8 discloses an online thermal error compensation method and system for CNC machine tools. This method collects temperature data from key measuring points of the CNC machine tool, calculates the theoretical thermal error value of the CNC machine tool based on a multiple linear regression thermal error model, calculates the compensation value, and determines whether it meets the set upper and lower limits of the compensation threshold. By constructing a multiple linear regression thermal error model and embedding it as an online thermal error compensation subunit into the human-machine interface of the control panel, an external compensator is not required, greatly improving the system's versatility. Simultaneously, fuzzy clustering analysis and multiple linear regression theory are used to calculate the CNC machine tool compensation value, and an external coordinate transformation method is employed to perform online compensation, resulting in convenient operation and strong real-time performance.

[0005] For example, Chinese patent CN202110602232.4 discloses a geometric error compensation method for a five-axis machine tool, the steps of which are as follows: Error model establishment: Based on the local exponential product formula, a full pose error model of the five-axis machine tool is established, and the position error model is obtained by separating the full pose error model; Error data acquisition: The five-axis machine tool is set to operate under linkage, keeping the distance between the tool tip trajectory and the workpiece end constant, and the distance error data of four combinations of forward and reverse rotation of the two rotating axes are measured using a ballbar; Actual command generation: The four sets of distance error data are input into the position error model to generate actual motion commands for the five-axis machine tool, and the actual motion commands are input into the control system of the five-axis machine tool. Furthermore, by distinguishing between the forward and reverse rotation of the rotating axes, the method effectively compensates for the error caused by the backlash of the transmission components of the five-axis machine tool.

[0006] However, in actual implementation, the inventors discovered that this type of technical solution mainly focuses on compensating for motion errors of the machine tool's motion axes during actual control, while errors introduced at the positioning level are ignored during the long machining process of a five-axis machine tool. This leads to poor machining accuracy due to positioning errors during machine tool operation. Summary of the Invention

[0007] To address the aforementioned problems in the prior art, a method for compensating for thermal errors in spatial positioning of CNC machine tools is provided; furthermore, a memory for implementing this method is also provided.

[0008] The specific technical solution is as follows:

[0009] A method for compensating for thermal errors in spatial positioning of CNC machine tools, comprising:

[0010] Step S1: Construct a positioning accuracy thermal error model with a temperature dependent variable for each motion axis of the machine tool to be compensated;

[0011] Step S2: Measure the actual positioning error of the machine tool to be compensated, and optimize the positioning accuracy thermal error model according to the actual positioning error to obtain an optimized model;

[0012] Step S3: Use the optimization model to compensate for the spatial positioning process of the machine tool to be compensated.

[0013] On the other hand, prior to step S1, the following is also included:

[0014] Step A11: Collect temperature data for the machine tool to be compensated to fit the machine tool temperature distribution data;

[0015] Step A12: Based on the machine tool temperature distribution data, several significant temperature difference points are obtained;

[0016] Step A13: Set up temperature sensors at the points with significant temperature differences and collect temperature data at the measurement points;

[0017] In step S1, the positioning accuracy thermal error model is constructed based on the temperature data of the measuring point of the temperature sensor.

[0018] On the other hand, step S1 includes:

[0019] Step S11: For each geometric error of each of the motion axes, a temperature-based sensitivity coefficient is generated using a polynomial;

[0020] Step S12: Add the temperature term as a dependent variable to the motion axis position-related geometric error model according to the sensitivity coefficient to obtain the positioning accuracy thermal error model.

[0021] On the other hand, in step S11, the method for generating the sensitivity coefficient includes:

[0022] In the formula, For the motion axis X-axis error term E XX The sensitivity coefficient, T i (t) represents the reading of the i-th temperature sensor at time t, k ij b represents the polynomial fitting coefficients for thermal error. ij This represents the bias of the polynomial fitting of the thermal error.

[0023] On the other hand, in step S12, the motion axis position-related geometric error model includes:

[0024]

[0025] In the formula, This is the transformation matrix of the tool coordinate system relative to the machine coordinate system;

[0026] The transformation matrix represents the transformation of the X-axis coordinate system relative to the machine tool coordinate system. The transformation matrix represents the geometric error of the X-axis coordinate system relative to the machine tool coordinate system.

[0027] The transformation matrix represents the transformation of the Y-axis coordinate system relative to the X-axis coordinate system. The transformation matrix represents the geometric error of the Y-axis coordinate system relative to the X-axis coordinate system.

[0028] The transformation matrix represents the transformation of the Z-axis coordinate system relative to the Y-axis coordinate system. The transformation matrix represents the geometric error of the Z-axis coordinate system relative to the Y-axis coordinate system.

[0029] The transformation matrix represents the transformation of the C-axis coordinate system relative to the Z-axis coordinate system of the motion axis. The transformation matrix represents the geometric error of the rotation axis C-axis coordinate system relative to the motion axis Z-axis coordinate system.

[0030] The transformation matrix represents the transformation between the coordinate system along the rotation axis A and the coordinate system along the rotation axis C. The transformation matrix represents the geometric error of the coordinate system along the rotation axis A relative to the coordinate system along the rotation axis C.

[0031] On the other hand, in step S12, the process of adding the temperature term dependent variable to the transformation matrix of the geometric error of the motion axis X-axis coordinate system relative to the machine tool coordinate system includes:

[0032]

[0033] In the formula, The transformation matrix represents the geometric error of the X-axis coordinate system relative to the machine tool coordinate system.

[0034] This indicates the X-axis position error of the moving axis in the current temperature coordinate state; This indicates the position error of the X-axis in the Y direction under the current temperature coordinate system. This indicates the Z-direction position error of the X-axis of the moving axis under the current temperature coordinate system. This indicates the X-axis angular error of the moving axis under the current temperature coordinate system. This indicates the Y-direction angular error of the X-axis of the moving axis under the current temperature coordinate state; This indicates the Z-direction angular error of the X-axis of the moving axis under the current temperature coordinate system.

[0035] On the other hand, the process of generating the X-direction position error of the moving axis X-axis under the current temperature coordinate state includes:

[0036]

[0037] In the formula, This is the geometric error term;

[0038] For the motion axis X-axis error term E XX Sensitivity coefficient;

[0039] T i(t) represents the reading of the i-th temperature sensor at time t;

[0040] k ij Represents the polynomial fitting coefficients for thermal error;

[0041] b ij This represents the bias of the polynomial fitting of the thermal error.

[0042] E XX (X) represents the error term of the motion axis X-axis.

[0043] On the other hand, step S2 includes:

[0044] Step S21: Configure different ambient temperatures and operating conditions for the machine tool to be compensated, and collect the actual positioning error at the end of the machine tool respectively;

[0045] Step S22: Optimize the bias term of the positioning accuracy thermal error model according to the actual positioning error, so that the predicted value of the positioning accuracy thermal error model conforms to the actual positioning error and is then used as the output of the optimized model.

[0046] On the other hand, step S3 includes:

[0047] Step S31: Construct a compensation table for each motion axis error term of the machine tool to be compensated at different temperatures according to the optimization model;

[0048] Step S32: During the actual processing, the compensation table is retrieved according to the data collected by the temperature sensor to compensate the machine tool to be compensated.

[0049] A five-axis machine tool, the five-axis machine tool including a control device, the control device including a processor and a memory;

[0050] The memory stores computer instructions. When the processor executes the computer instructions, it performs the above-mentioned CNC machine tool spatial positioning thermal error compensation method on the five-axis machine tool.

[0051] The above technical solution has the following advantages or beneficial effects:

[0052] To address the problem of limited overall machining accuracy caused by the lack of compensation for machine tool positioning errors in existing technologies, this solution constructs a positioning accuracy thermal error model for each motion axis before positioning, incorporating a temperature-dependent variable. This unifies the geometric and thermal errors during positioning and optimizes the model based on actual positioning errors. Consequently, in subsequent actual positioning processes, it effectively compensates for positioning offsets caused by geometric and thermal errors, thereby improving the machining accuracy of the machine tool. Attached Figure Description

[0053] Embodiments of the invention will be described more fully with reference to the accompanying drawings. However, the drawings are for illustration and explanation only and do not constitute a limitation on the scope of the invention.

[0054] Figure 1 This is an overall schematic diagram of an embodiment of the present invention;

[0055] Figure 2 This is a schematic diagram of step A1 in an embodiment of the present invention;

[0056] Figure 3 This is a schematic diagram of step S1 in an embodiment of the present invention;

[0057] Figure 4 This is a schematic diagram of step S2 in an embodiment of the present invention;

[0058] Figure 5 This is a schematic diagram of step S3 in an embodiment of the present invention. Detailed Implementation

[0059] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0061] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0062] This invention includes:

[0063] A method for compensating for thermal errors in spatial positioning of CNC machine tools, such as Figure 1 As shown, it includes:

[0064] Step S1: Construct a positioning accuracy thermal error model with a temperature dependent variable for each motion axis of the machine tool to be compensated;

[0065] Step S2: Measure the actual positioning error of the machine tool to be compensated, and optimize the positioning accuracy thermal error model according to the actual positioning error to obtain the optimized model;

[0066] Step S3: Use an optimization model to compensate for the spatial positioning process of the machine tool to be compensated.

[0067] Specifically, in response to the problem that the lack of compensation for machine tool positioning errors in existing technologies leads to limited overall machining accuracy, this embodiment constructs a positioning accuracy thermal error model with a temperature dependent variable for each motion axis before positioning. This unifies the geometric and thermal errors during the positioning process and optimizes the model based on the actual positioning error. This allows for effective compensation for positioning offsets caused by geometric and thermal errors during subsequent actual positioning processes, thereby improving the machining accuracy of the machine tool.

[0068] Specifically, the machine tool to be compensated is a five-axis machine tool or other equivalent machine tool equipment, which has three motion axes (X, Y, Z) and two rotary axes (A, C), and also includes equipment such as control motors, transmission shafts, water cooling systems, electric spindles, and control devices.

[0069] Each motion axis and rotary axis is equipped with a positioning device, such as an optical grating sensor, magnetic scale, or other equivalent positioning device, which can detect the current position parameters of each axis and provide them as positioning data to the control device. The control device needs to use these position parameters in conjunction with relevant algorithms and machine tool modeling to achieve spatial positioning of the end effector of the machine tool, usually the cutting tool. Based on this, the control device then controls the cutting tool to perform machining according to a preset machining trajectory.

[0070] However, each motion axis and rotation axis itself will have certain geometric errors during the manufacturing process. For example, the actual length, curvature and other data are not completely consistent with the ideal model. This will cause the control device to produce a certain positioning deviation when performing end-effector spatial positioning according to the ideal model.

[0071] Furthermore, as the machining process proceeds, the machine tool temperature gradually rises, causing thermal expansion of each axis. This thermal error further leads to positioning deviation of the control device, affecting machining accuracy.

[0072] To address this issue, the technical means introduced in this embodiment mainly include constructing a motion axis position-related geometric error model based on the geometrically related positioning error obtained from actual measurements, and then adding a temperature term as a dependent variable to the motion axis position-related geometric error model to form a positioning accuracy thermal error model that can compensate for both geometric and thermal errors.

[0073] Then, the actual positioning error is obtained by designing corresponding test conditions, and the model is corrected based on the actual positioning error to make it conform to reality.

[0074] Finally, when the machine tool is positioned, the positioning process can be compensated based on the optimization model, thereby accurately positioning the end effector and improving machining accuracy.

[0075] In one embodiment, such as Figure 2 As shown, the procedure before step S1 also includes:

[0076] Step A11: Collect temperature data of the machine tool to be compensated to fit the machine tool temperature distribution data;

[0077] Step A12: Based on the machine tool temperature distribution data, several significant temperature difference points were identified;

[0078] Step A13: Set up temperature sensors at points with significant temperature differences and collect temperature data at the measurement points;

[0079] In step S1, a positioning accuracy thermal error model is constructed based on the temperature data of the measuring points of the temperature sensor.

[0080] Specifically, to achieve better thermal compensation, before modeling, temperature data is first collected for various parts of the machine tool to be compensated, especially locations with heat sources and moving axes, and then fitted to obtain machine tool temperature distribution data. This machine tool temperature distribution data may be static data or data that changes over time, depending on the embodiment. Then, based on the machine tool temperature distribution data, several significant temperature difference points are identified. Temperature sensors are then installed at these significant temperature difference points to collect temperature data, achieving a good acquisition and characterization of the machine tool's temperature state. Subsequent modeling and compensation processes will be implemented around the layout of these temperature sensors.

[0081] In one embodiment, such as Figure 3 As shown, step S1 includes:

[0082] Step S11: Generate a temperature-based sensitivity coefficient using a polynomial for each geometric error of each motion axis;

[0083] Step S12: Add a temperature term as a dependent variable to the motion axis position-related geometric error model according to the sensitivity coefficient to obtain the positioning accuracy thermal error model.

[0084] Specifically, in order to achieve a better positioning compensation effect, in this embodiment, a temperature-based sensitivity coefficient is first generated using a polynomial for each geometric error of each motion axis, and then a temperature term is added as a dependent variable to the motion axis position-related geometric error model to realize the model construction.

[0085] Specifically, in step S11, taking the motion axis X-axis as an example, the method for generating the sensitivity coefficient of the X-axis includes:

[0086]

[0087] In the formula, For the motion axis X-axis error term E XX Sensitivity coefficient;

[0088] Ti (t) represents the reading of the i-th temperature sensor at time t;

[0089] k ij Represents the polynomial fitting coefficients for thermal error;

[0090] b ij This represents the bias of the polynomial fitting of the thermal error.

[0091] The fitting coefficients and fitting biases are calibrated according to the actual positioning error during subsequent optimization.

[0092] The polynomial fitting process is based on a combination of multiple previously configured temperature sensors. The remaining axes, including the Y-axis, Z-axis, A-axis, and C-axis, can also be fitted to the sensitivity coefficients using the aforementioned formula. These sensitivity coefficients are subsequently used to weight the degree of thermal error for each axis.

[0093] In addition, the geometric error model related to the position of the motion axis includes:

[0094]

[0095] In the formula, This is the transformation matrix of the tool coordinate system relative to the machine coordinate system;

[0096] This represents the transformation matrix of the X-axis coordinate system relative to the machine tool coordinate system. This is the transformation matrix representing the geometric error of the X-axis coordinate system relative to the machine tool coordinate system;

[0097] This represents the transformation matrix between the Y-axis coordinate system and the X-axis coordinate system. This is the transformation matrix representing the geometric error between the Y-axis coordinate system and the X-axis coordinate system.

[0098] This represents the transformation matrix between the Z-axis coordinate system and the Y-axis coordinate system. This is the transformation matrix for the geometric error of the Z-axis coordinate system relative to the Y-axis coordinate system.

[0099] This represents the transformation matrix between the C-axis coordinate system (representing the rotation axis) and the Z-axis coordinate system (representing the motion axis). The transformation matrix represents the geometric error of the rotation axis C-axis coordinate system relative to the motion axis Z-axis coordinate system.

[0100] This represents the transformation matrix between the coordinate system along the rotation axis A and the coordinate system along the rotation axis C. Let be the transformation matrix representing the geometric error of the coordinate system along the rotation axis A relative to the coordinate system along the rotation axis C.

[0101] The five-axis machine tool spatial positioning error model has a total of 46 geometric error terms. Among them, each of the three linear axes has 6 geometric error terms, the three linear axes themselves have 6×3=18 error terms, there are 3 perpendicular errors between the linear axes, the two rotary axes themselves have 6×2=12 error terms, the rotary axes are independent of the position errors of other axes and have 4×2=8 error terms, and the machine tool spindle has 5 geometric error terms. Therefore, there are a total of 46 geometric error terms.

[0102] Based on this, a corresponding temperature term can be added as a dependent variable to the transformation matrix of the geometric error.

[0103] Taking the X-axis as an example, step S12, which involves adding a temperature term as a dependent variable to the transformation matrix of the geometric error between the X-axis coordinate system and the machine tool coordinate system, includes:

[0104] In the formula, This is the transformation matrix representing the geometric error of the X-axis coordinate system relative to the machine tool coordinate system;

[0105] This indicates the X-axis position error of the moving axis in the current temperature coordinate state; This indicates the position error of the X-axis in the Y direction under the current temperature coordinate system. This indicates the Z-direction position error of the X-axis of the moving axis under the current temperature coordinate system. This indicates the X-axis angular error of the moving axis under the current temperature coordinate system. This indicates the Y-direction angular error of the X-axis of the moving axis under the current temperature coordinate state; This indicates the Z-direction angular error of the X-axis of the moving axis under the current temperature coordinate system.

[0106] Specifically, in order to achieve a better assessment of the thermal error of each motion axis, in this embodiment, for each moving axis, such as the X-axis, the positional and angular errors in the X, Y, and Z directions generated at the corresponding temperature nodes are measured, thereby achieving compensation for the corresponding motion axis.

[0107] The process of generating the X-axis position error of the moving axis in the current temperature coordinate state includes:

[0108]

[0109] In the formula, This is the geometric error term;

[0110] For the motion axis X-axis error term E XX Sensitivity coefficient;

[0111] T i (t) represents the reading of the i-th temperature sensor at time t;

[0112] k ij Represents the polynomial fitting coefficients for thermal error;

[0113] b ij This represents the bias of the polynomial fitting of the thermal error.

[0114] E XX (X) represents the error term of the motion axis X-axis.

[0115] Based on the above formula, by adjusting the fitting coefficient and fitting bias, it is possible to estimate the error of the corresponding moving axis in the corresponding direction or angle.

[0116] By repeating the correction to the above formula, we can obtain the position and angle errors of the X-axis in the X, Y, and Z directions under the current temperature coordinate system.

[0117] By repeating the above process, position and angle errors caused by geometric and thermal errors in the X, Y, and Z directions of the motion axis Y-axis, motion axis Z-axis, rotation axis A-axis, and rotation axis C-axis can be compensated respectively.

[0118] In one embodiment, such as Figure 4 As shown, step S2 includes:

[0119] Step S21: Configure the machine tool to be compensated with different ambient temperatures and operating conditions, and collect the actual positioning error at the end of the machine tool respectively;

[0120] Step S22: Optimize the bias term of the positioning accuracy thermal error model according to the actual positioning error, so that the predicted value of the positioning accuracy thermal error model matches the actual positioning error and is then used as the output of the optimized model.

[0121] Specifically, in order to achieve better positioning process compensation, in this embodiment, different ambient temperatures are first configured as test scenarios for the machine tool to be compensated, and the machine tool movement is controlled at the corresponding temperature nodes. Then, the actual spatial position of the end effector is measured and compared with the spatial position currently calculated by the control device to obtain the actual positioning error.

[0122] Then, the bias term of the positioning accuracy thermal error model is optimized according to the actual positioning error, so that the predicted value of the positioning accuracy thermal error model matches the actual positioning error and is then used as the output of the optimized model. Similarly, for multiple motion axes and rotation axes, their motion needs to be controlled and parameters calibrated at different temperature nodes.

[0123] In one embodiment, such as Figure 5 As shown, step S3 includes:

[0124] Step S31: Construct a compensation table for each motion axis error term of the machine tool to be compensated at different temperatures according to the optimization model;

[0125] Step S32: During the actual processing, the compensation table is retrieved according to the data collected by the temperature sensor to compensate the machine tool to be compensated.

[0126] Specifically, after completing the above model construction, in order to simplify control, a compensation table corresponding to the error terms of each motion axis of the machine tool to be compensated at different temperatures can be constructed according to the optimization model. Subsequently, in the positioning process, the current temperature node is first determined according to the temperature sensor, and then the positioning data of each motion axis and rotation axis is collected through the positioning device. The compensation value is determined by looking up the table. Based on the actual positioning data and the compensation value, the spatial position of the positioning end is correctly calculated.

[0127] A five-axis machine tool, the five-axis machine tool including a control device, the control device including a processor and a memory;

[0128] The memory stores computer instructions. When the processor executes the computer instructions, it performs the above-mentioned CNC machine tool spatial positioning thermal error compensation method on the five-axis machine tool.

[0129] Those skilled in the art will understand that various aspects, or possible implementations of various aspects, of the present invention can be embodied as systems, methods, or computer program products. Therefore, various aspects, or possible implementations of various aspects, of the present invention can take the form of entirely hardware embodiments, entirely software embodiments (including firmware, resident software, etc.), or embodiments combining software and hardware aspects, all collectively referred to herein as "circuit," "module," or "system." Furthermore, various aspects, or possible implementations of various aspects, of the present invention can take the form of computer program products, which are computer-readable program codes stored on a computer-readable medium.

[0130] Computer-readable media can be computer-readable signal media or computer-readable storage media. Computer-readable storage media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, or apparatuses, or any suitable combination thereof, such as random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, and portable read-only memory (CD-ROM).

[0131] A processor in a computer reads computer-readable program code stored in a computer-readable medium, enabling the processor to perform the functional actions specified in each step or combination of steps in a flowchart; and to generate means for implementing the functional actions specified in each block or combination of blocks in a flowchart.

[0132] It should be understood that a processor in a computer can be understood as one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers (MCUs), microprocessors, or other electronic components implemented to execute the aforementioned computer-readable program code.

[0133] Computer-readable program code may execute entirely on the user's local computer, partially on the user's local computer, as a separate software package, partially on the user's local computer and partially on a remote computer, or entirely on a remote computer or server. It should also be noted that in some alternative implementations, the functions indicated by the steps in the flowchart or the blocks in the block diagram may not occur in the order shown in the diagram. For example, depending on the functions involved, two consecutive steps or blocks may actually be executed approximately simultaneously, or these blocks may sometimes be executed in reverse order.

[0134] The above are merely preferred embodiments of the present invention and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should recognize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for compensating for thermal errors in spatial positioning of CNC machine tools, characterized in that, include: Step S1: Construct a positioning accuracy thermal error model with a temperature dependent variable for each motion axis of the machine tool to be compensated; Step S2: Measure the actual positioning error of the machine tool to be compensated, and optimize the positioning accuracy thermal error model according to the actual positioning error to obtain an optimized model; Step S3: Use the optimization model to compensate for the spatial positioning process of the machine tool to be compensated; Step S1 includes: Step S11: For each geometric error of each of the motion axes, a temperature-based sensitivity coefficient is generated using a polynomial; Step S12: Add the temperature term as a dependent variable to the motion axis position-related geometric error model according to the sensitivity coefficient to obtain the positioning accuracy thermal error model; In step S11, the method for generating the sensitivity coefficient includes: ； In the formula, For the motion axis X-axis error term The sensitivity coefficient, Indicates the first A temperature sensor in Readings at time, Represents the polynomial fitting coefficients for thermal error. This represents the bias of the polynomial fitting of the thermal error.

2. The CNC machine tool spatial positioning thermal error compensation method according to claim 1, characterized in that, The procedure preceding step S1 also includes: Step A11: Collect temperature data for the machine tool to be compensated to fit the machine tool temperature distribution data; Step A12: Based on the machine tool temperature distribution data, several significant temperature difference points are obtained; Step A13: Set up temperature sensors at the points with significant temperature differences and collect temperature data at the measuring points; In step S1, the positioning accuracy thermal error model is constructed based on the temperature data of the measuring point of the temperature sensor.

3. The CNC machine tool spatial positioning thermal error compensation method according to claim 1, characterized in that, In step S12, the motion axis position-related geometric error model includes: ； In the formula, This is the transformation matrix of the tool coordinate system relative to the machine coordinate system; The transformation matrix represents the transformation of the X-axis coordinate system relative to the machine tool coordinate system. The transformation matrix represents the geometric error of the X-axis coordinate system relative to the machine tool coordinate system. The transformation matrix represents the transformation of the Y-axis coordinate system relative to the X-axis coordinate system. The transformation matrix represents the geometric error of the Y-axis coordinate system relative to the X-axis coordinate system. The transformation matrix represents the transformation of the Z-axis coordinate system relative to the Y-axis coordinate system. The transformation matrix represents the geometric error of the Z-axis coordinate system relative to the Y-axis coordinate system. The transformation matrix represents the transformation of the C-axis coordinate system relative to the Z-axis coordinate system of the motion axis. The transformation matrix represents the geometric error of the rotation axis C-axis coordinate system relative to the motion axis Z-axis coordinate system. The transformation matrix represents the transformation between the coordinate system along the rotation axis A and the coordinate system along the rotation axis C. The transformation matrix represents the geometric error of the coordinate system along the rotation axis A relative to the coordinate system along the rotation axis C.

4. The CNC machine tool spatial positioning thermal error compensation method according to claim 3, characterized in that, In step S12, the process of adding the temperature term as a dependent variable to the transformation matrix of the geometric error between the motion axis X-axis coordinate system and the machine tool coordinate system includes: ； In the formula, The transformation matrix represents the geometric error of the X-axis coordinate system relative to the machine tool coordinate system. This indicates the X-axis position error of the moving axis in the current temperature coordinate system. This indicates the position error of the X-axis in the Y direction under the current temperature coordinate system. This indicates the Z-direction position error of the X-axis of the moving axis under the current temperature coordinate system. This indicates the X-axis angular error of the moving axis under the current temperature coordinate system. This indicates the Y-direction angular error of the X-axis of the moving axis under the current temperature coordinate state; This indicates the Z-direction angular error of the X-axis of the moving axis under the current temperature coordinate system.

5. The CNC machine tool spatial positioning thermal error compensation method according to claim 4, characterized in that, The process of generating the X-axis position error of the moving axis in the current temperature coordinate state includes: ； In the formula, For geometric error terms, For the motion axis X-axis error term The sensitivity coefficient, Indicates the first A temperature sensor in Readings at time, Represents the polynomial fitting coefficients for thermal error. This represents the bias of the polynomial fitting for thermal error. This is the error term for the X-axis of the motion axis.

6. The CNC machine tool spatial positioning thermal error compensation method according to claim 1, characterized in that, Step S2 includes: Step S21: Configure different ambient temperatures and operating conditions for the machine tool to be compensated, and collect the actual positioning error at the end of the machine tool respectively; Step S22: Optimize the bias term of the positioning accuracy thermal error model according to the actual positioning error, so that the predicted value of the positioning accuracy thermal error model conforms to the actual positioning error and is then used as the output of the optimized model.

7. The CNC machine tool spatial positioning thermal error compensation method according to claim 1, characterized in that, Step S3 includes: Step S31: Construct a compensation table for each motion axis error term of the machine tool to be compensated at different temperatures according to the optimization model; Step S32: During the movement of the machine tool to be compensated, the compensation table is retrieved according to the data collected by the temperature sensor to compensate the spatial positioning parameters of the machine tool to be compensated.

8. A five-axis machine tool, characterized in that, The five-axis machine tool includes a control device, which includes a processor and a memory; The memory stores computer instructions. When the processor executes the computer instructions, it performs the CNC machine tool spatial positioning thermal error compensation method as described in any one of claims 1-7 on the five-axis machine tool.

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