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

Abstract

The invention relates to the technical field of five-axis machine tool control, in particular to a numerical control machine tool space positioning thermal error compensation method and a five-axis machine tool, and the method comprises the steps: constructing a positioning precision thermal error model containing temperature term dependent variables for each motion axis of a machine tool to be compensated; actual positioning errors of the machine tool to be compensated are measured, and the positioning precision thermal error model is optimized according to the actual positioning errors to obtain an optimized model; and the optimization model is adopted to compensate the space positioning process of the machine tool to be compensated. In order to solve the problem that the overall machining precision is limited due to the fact that compensation for the positioning error of a machine tool is lacked in the prior art, a positioning precision thermal error model containing temperature term dependent variables is constructed for each motion axis before positioning, so that geometric errors and thermal errors are unified in the positioning process; and positioning deviation caused by geometric errors and thermal errors in the machine tool positioning process can be effectively compensated, and the machining precision of the machine tool is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of five-axis machine tool control, and in particular to a method for compensating thermal errors in spatial positioning of a numerically controlled machine tool and a five-axis machine tool. Background Art

[0002] CNC machine tools, short for Computer numerical control machine tools, are automated machine tools equipped with a program control system. The control system can logically process programs specified by control codes or other symbolic instructions, decode them, represent them in coded numbers, and input them into the CNC device through information carriers. After calculation and processing, the CNC device sends various control signals to control the movement of the machine tool, and automatically processes the parts according to the shape and size required by the drawing. In order to achieve better processing accuracy, it is usually necessary to consider the errors generated by the axes of the CNC machine tool during movement. Generally speaking, the errors mainly include the geometric errors generated by the moving parts of the machine tool during movement, and the thermal errors introduced by the heat elongation of the parts during the processing of the machine tool.

[0003] In the prior art, there are certain methods for compensating for geometric errors and thermal errors of machine tools during their motion.

[0004] For example, Chinese patent CN201610159196.8 discloses a method and system for online compensation of thermal errors of CNC machine tools; temperature data of key measuring points of CNC machine tools are collected, theoretical thermal error values ​​of CNC machine tools are calculated according to the multivariate linear regression thermal error model, compensation values ​​are calculated and it is judged whether the set upper and lower limits of compensation thresholds are met. By constructing a multivariate linear regression thermal error model, it is embedded into the human-computer interaction interface of the panel control unit as an online compensation subunit of thermal errors of CNC machine tools, without the need for an external compensator, which greatly improves the versatility of the system; at the same time, the compensation values ​​of CNC machine tools are calculated using fuzzy clustering analysis methods and multivariate linear regression theory, and online compensation is performed using external coordinate transformation, which is convenient to operate and highly real-time.

[0005] For another example, Chinese patent CN202110602232.4 discloses a geometric error compensation method for a five-axis machine tool, and the steps are as follows: error model establishment, based on the local exponential product formula, the full posture error model of the five-axis machine tool is established, and the full posture error model is separated to obtain the position error model; error data acquisition, the five-axis machine tool is set in linkage, so that the tool tip trajectory keeps a constant distance between the workpiece end and the spindle end, and the ballbar is used to measure the distance error data of four combinations of the forward and reverse operation of the two rotating axes; actual instruction generation, the four sets of distance error data are input into the position error model, the actual motion instructions of the five-axis machine tool are generated, and the actual motion instructions are input into the control system of the five-axis machine tool. The error caused by the reverse clearance of the transmission components of the five-axis machine tool is also effectively compensated by distinguishing the forward and reverse directions of the rotating axis.

[0006] However, in the actual implementation process, the inventor found that this type of technical solution mainly focuses on compensating the motion error of the machine tool's motion axis during actual control, while the error introduced by the positioning level is ignored during the long processing of the five-axis machine tool. This leads to the problem that the machine tool is prone to poor processing accuracy due to positioning errors during operation. Summary of the invention

[0007] In view of the above problems existing in the prior art, a method for compensating for thermal errors in spatial positioning of a CNC machine tool is provided. On the other hand, a memory for implementing the method for compensating for thermal errors in spatial positioning of a CNC machine tool is also provided.

[0008] The specific technical solutions are as follows:

[0009] A method for compensating thermal errors in spatial positioning of a numerically controlled machine tool, comprising:

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

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

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

[0013] On the other hand, before step S1, the method further includes:

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

[0015] Step A12: Filtering the machine tool temperature distribution data to obtain a plurality of significant temperature difference points;

[0016] Step A13: installing a temperature sensor at the point of significant temperature difference and collecting temperature data of the measuring point;

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

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

[0019] Step S11: using a polynomial to generate a temperature-based sensitivity coefficient for each geometric error of each of the motion axes;

[0020] Step S12: adding the temperature term 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, E is the error term of the X axis of the motion axis XX The sensitivity coefficient, T i (t) represents the reading of the ith temperature sensor at time t, k ij represents the thermal error polynomial fitting coefficient, b ij represents the thermal error polynomial fit bias.

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

[0024]

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

[0026] represents the transformation matrix of the motion axis X-axis coordinate system relative to the machine tool coordinate system, is a transformation matrix of the geometric error of the motion axis X-axis coordinate system relative to the machine tool coordinate system;

[0027] represents the transformation matrix of the motion axis Y axis coordinate system relative to the motion axis X axis coordinate system, is a transformation matrix of the geometric error of the motion axis Y-axis coordinate system relative to the motion axis X-axis coordinate system;

[0028] represents the transformation matrix of the motion axis Z axis coordinate system relative to the motion axis Y axis coordinate system, is a transformation matrix of the geometric error of the motion axis Z-axis coordinate system relative to the motion axis Y-axis coordinate system;

[0029] represents the transformation matrix of the rotation axis C-axis coordinate system relative to the motion axis Z-axis coordinate system, is a transformation matrix of the geometric error of the rotation axis C-axis coordinate system relative to the motion axis Z-axis coordinate system;

[0030] represents the transformation matrix of the rotation axis A axis coordinate system relative to the rotation axis C axis coordinate system, is the transformation matrix of the geometric error of the rotation axis A-axis coordinate system relative to the rotation axis C-axis coordinate system.

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

[0034] Indicates the X-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the Y-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the Z-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the X-direction angle error of the moving axis X-axis under the current temperature coordinate state; Indicates the Y-direction angle error of the moving axis X-axis under the current temperature coordinate state; Indicates the Z-direction angle error of the moving axis X-axis under the current temperature coordinate state.

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

[0036]

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

[0038] E is the error term of the X axis of the motion axis XX The sensitivity coefficient of

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

[0040] k ij represents the thermal error polynomial fitting coefficient;

[0041] b ij represents the thermal error polynomial fit bias;

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

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

[0044] Step S21: configuring different ambient temperatures and working conditions for the machine tool to be compensated, and collecting actual positioning errors of the end of the machine tool respectively;

[0045] Step S22: Optimizing 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 output as the optimization model.

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

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

[0048] Step S32: During the actual machining process, 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 comprising a control device, the control device comprising a processor and a memory;

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

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

[0052] In order to solve the problem that the existing technology lacks compensation for the positioning error of the machine tool, resulting in limited overall machining accuracy, in this solution, a positioning accuracy thermal error model containing a temperature term dependent variable is constructed for each moving axis before positioning, so that the geometric error and thermal error are unified in the positioning process, and the model is optimized in combination with the actual positioning error. In the subsequent actual positioning process, the positioning offset caused by the geometric error and thermal error in the machine tool positioning process can be effectively compensated, thereby improving the machining accuracy of the machine tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The embodiments of the present invention will be described more fully with reference to the attached drawings, which are provided for illustration and description only and are not intended to limit the scope of the present invention.

[0054] Figure 1 It 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 Schematic diagram of step S3 in an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0061] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0062] The present invention comprises:

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

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

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

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

[0067] Specifically, in order to address the problem in the prior art that the overall machining accuracy is limited due to the lack of compensation for the positioning error of the machine tool, in this embodiment, a positioning accuracy thermal error model including a temperature term dependent variable is constructed for each moving axis before positioning, so that the geometric error and the thermal error are unified during the positioning process, and the model is optimized in combination with the actual positioning error. In the subsequent actual positioning process, the positioning offset caused by the geometric error and the thermal error during the positioning process of the machine tool can be effectively compensated, 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 of X, Y, and Z and two rotation axes of A and C, and also includes control motors, transmission shafts, water cooling systems, electric spindles, control devices and other equipment.

[0069] Among them, each motion axis and rotation axis is equipped with a relevant positioning device, such as a grating sensor, a magnetic scale or other equivalent positioning device, which can detect the current position parameters of each axis and provide them to the control device as positioning data. The control device needs to realize the spatial positioning of the end of the machine tool, usually the tool, according to these position parameters combined with relevant algorithms and machine tool modeling, and then control the tool on this basis to make it process according to the preset processing trajectory.

[0070] However, there will be certain geometric errors in each motion axis and rotation axis during the processing. For example, the actual length, curvature and other data are not completely consistent with the ideal modeling. This leads to certain positioning deviations when the control device performs end space positioning according to the ideal modeling.

[0071] As the machining process progresses, the temperature of the machine tool will gradually rise, causing thermal expansion of each axis. This thermal error further causes the positioning deviation of the control device, affecting the machining accuracy.

[0072] To address this problem, the technical means introduced in this embodiment mainly include obtaining geometrically related positioning errors according to actual measurements, constructing a moving axis position-related geometric error model, and then adding a temperature term dependent variable to the moving axis position-related geometric error model to form a positioning accuracy thermal error model that can compensate for both geometric error and thermal error dimensions.

[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 consistent with reality.

[0074] Finally, when the machine tool is positioned, the positioning process can be compensated based on the optimization model, so that the end can be accurately positioned to improve the processing accuracy.

[0075] In one embodiment, Figure 2 As shown, before step S1, it also includes:

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

[0077] Step A12: Filter and obtain a plurality of significant temperature difference points according to the temperature distribution data of the machine tool;

[0078] Step A13: Setting a temperature sensor at a point with a significant temperature difference and collecting temperature data of the measuring point;

[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, in order to achieve a better thermal compensation effect, before modeling, temperature data is first collected for each part of the machine tool to be compensated, especially the location where the heat source exists and the moving axis, and then the machine tool temperature distribution data is fitted. The machine tool temperature distribution data may be static data or data that changes over time according to the embodiment. Then, a plurality of significant temperature difference points are obtained by screening according to the machine tool temperature distribution data, and temperature sensors are set at the significant temperature difference points and the temperature data of the measuring points are collected, so as to achieve a better collection and characterization of the temperature state of the machine tool. The subsequent modeling process and compensation process will be realized around the temperature sensor layout.

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

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

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

[0084] Specifically, in order to achieve better positioning compensation effect, in this embodiment, a polynomial is first used to generate a temperature-based sensitivity coefficient for each geometric error of each motion axis, and then the temperature term dependent variable is added to the motion axis position-related geometric error model to realize 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, E is the error term of the X axis of the motion axis XX The sensitivity coefficient of

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

[0089] k ij represents the thermal error polynomial fitting coefficient;

[0090] b ij represents the thermal error polynomial fit bias.

[0091] The fitting coefficient and fitting bias are calibrated according to the actual positioning error in the subsequent optimization process.

[0092] The polynomial fitting process is implemented based on the combination of multiple temperature sensors configured previously. The remaining axes, including the motion axis Y, motion axis Z, rotation axis A and rotation axis C, can all be fitted with the sensitivity coefficient according to the above formula. The sensitivity coefficient is mainly used to weight the thermal error degree of each axis in the future.

[0093] And, the motion axis position related geometric error model includes:

[0094]

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

[0096] Represents the transformation matrix of the X-axis coordinate system of the motion axis relative to the machine tool coordinate system, is the transformation matrix of the geometric error of the X-axis coordinate system of the motion axis relative to the machine tool coordinate system;

[0097] Represents the transformation matrix of the motion axis Y axis coordinate system relative to the motion axis X axis coordinate system, is the transformation matrix of the geometric error of the motion axis Y axis coordinate system relative to the motion axis X axis coordinate system;

[0098] Represents the transformation matrix of the motion axis Z axis coordinate system relative to the motion axis Y axis coordinate system, is the transformation matrix of the geometric error of the moving axis Z axis coordinate system relative to the moving axis Y axis coordinate system;

[0099] Represents the transformation matrix of the rotation axis C-axis coordinate system relative to the motion axis Z-axis coordinate system, is the transformation matrix of the geometric error of the rotating axis C-axis coordinate system relative to the moving axis Z-axis coordinate system;

[0100] Represents the transformation matrix of the rotation axis A axis coordinate system relative to the rotation axis C axis coordinate system, It is the transformation matrix of the geometric error of the rotation axis A-axis coordinate system relative to the rotation axis C-axis coordinate system.

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

[0102] On this basis, the corresponding temperature term dependent variable can be added to the transformation matrix part of the geometric error.

[0103] Still taking the X axis of the motion axis as an example, in step S12, the process of adding the temperature term dependent variable to the transformation matrix of the geometric error of the X axis coordinate system of the motion axis relative to the machine tool coordinate system includes:

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

[0105] Indicates the X-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the Y-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the Z-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the X-direction angle error of the moving axis X-axis under the current temperature coordinate state; Indicates the Y-direction angle error of the moving axis X-axis under the current temperature coordinate state; Indicates the Z-direction angle error of the moving axis X-axis under the current temperature coordinate state.

[0106] Specifically, in order to achieve a better evaluation of the thermal errors of each moving axis, in this embodiment, for each moving axis, such as the moving axis X, the position errors and angle errors in the X, Y, and Z directions at the corresponding temperature nodes are measured, thereby achieving compensation for the corresponding moving axis.

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

[0108]

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

[0110] E is the error term of the X axis of the motion axis XX The sensitivity coefficient of

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

[0112] k ij represents the thermal error polynomial fitting coefficient;

[0113] b ij represents the thermal error polynomial fit bias;

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

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

[0116] By repeatedly correcting the above formula, the position error and angle error of the moving axis X in the X, Y, and Z directions under the current temperature coordinate state can be obtained.

[0117] By further repeating the above process, the position error and angle error caused by geometric error and thermal error in the three directions of X, Y and Z of the moving axis Y, the moving axis Z, the rotating axis A and the rotating axis C can be compensated respectively.

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

[0119] Step S21: configuring different ambient temperatures and working conditions for the machine tool to be compensated, and collecting the actual positioning error of the end of the machine tool respectively;

[0120] Step S22: Optimizing 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 output as an optimized model.

[0121] Specifically, in order to achieve better positioning process compensation, in this embodiment, different ambient temperatures are first configured for the machine tool to be compensated as test scenarios, and the machine tool movement is controlled at the corresponding temperature nodes. Then, the actual spatial position of the end is measured and compared with the spatial position currently solved 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 is consistent with the actual positioning error and then output as the optimization model. Similarly, for multiple motion axes and rotation axes, they need to be controlled to move and calibrate parameters at different temperature nodes.

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

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

[0125] Step S32: During the actual machining process, 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-mentioned model construction, in order to simplify the 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. In the subsequent 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, and the compensation value is determined by looking up the table, and the spatial position of the positioning end is correctly calculated based on the actual positioning data and the compensation value.

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

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

[0129] Those skilled in the art will appreciate that various aspects of the present invention, or possible implementations of various aspects, can be specifically implemented as systems, methods or computer program products. Therefore, various aspects of the present invention, or possible implementations of various aspects, can adopt the form of complete hardware embodiments, complete software embodiments (including firmware, resident software, etc.), or combined software and hardware embodiments, all collectively referred to as "circuit", "module" or "system" here. In addition, various aspects of the present invention, or possible implementations of various aspects, can adopt the form of computer program products, which refer to computer-readable program codes stored in computer-readable media.

[0130] The computer readable medium may be a computer readable signal medium or a computer readable storage medium. The computer readable storage medium includes but is not limited to electronic, magnetic, optical, electromagnetic, infrared or semiconductor systems, devices or apparatuses, or any suitable combination of the foregoing, such as random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable read-only memory (CD-ROM).

[0131] The processor in the computer reads the computer-readable program code stored in the computer-readable medium, so that the processor can execute the functional actions specified in each step or the combination of steps in the flowchart; and generate a device for implementing the functional actions specified in each block or the combination of blocks in the block diagram.

[0132] It should be understood that the processor in the 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 codes.

[0133] Computer readable program code can be executed completely on the local computer of the user, partially on the local computer of the user, as a separate software package, partially on the local computer of the user and partially on the remote computer, or executed completely on the remote computer or server.It should also be noted that in some alternative embodiments, the functions noted in each step in the flow chart or each block in the block diagram may not occur in the order noted in the figure.For example, depending on the function involved, two steps shown in succession or two blocks may actually be executed roughly simultaneously, or these blocks may sometimes be executed in reverse order.

[0134] The above are only 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 be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for compensating thermal errors in spatial positioning of CNC machine tools, characterized in that: include: Step S1: constructing a positioning accuracy thermal error model including a temperature dependent variable for each motion axis of the machine tool to be compensated; Step S2: measuring the actual positioning error of the machine tool to be compensated, and optimizing the positioning accuracy thermal error model according to the actual positioning error to obtain an optimized model; Step S3: using the optimization model to compensate for the spatial positioning process of the machine tool to be compensated.

2. The method for compensating the spatial positioning thermal error of a CNC machine tool according to claim 1, characterized in that: Before step S1, the following steps are also included: Step A11: collecting temperature data of the machine tool to be compensated to fit the temperature distribution data of the machine tool; Step A12: Filtering the machine tool temperature distribution data to obtain a plurality of significant temperature difference points; Step A13: installing a temperature sensor at the point of significant temperature difference and collecting temperature data of the measuring point; In the step S1, the positioning accuracy thermal error model is constructed based on the temperature data of the measuring points of the temperature sensor.

3. The method for compensating the spatial positioning thermal error of a CNC machine tool according to claim 1, characterized in that: The step S1 comprises: Step S11: using a polynomial to generate a temperature-based sensitivity coefficient for each geometric error of each of the motion axes; Step S12: adding the temperature term dependent variable to the motion axis position related geometric error model according to the sensitivity coefficient to obtain the positioning accuracy thermal error model.

4. The method for compensating the spatial positioning thermal error of a CNC machine tool according to claim 3, characterized in that: In step S11, the method for generating the sensitivity coefficient includes: In the formula, E is the error term of the X axis of the motion axis XX The sensitivity coefficient, T i (t) represents the reading of the ith temperature sensor at time t, k ij represents the thermal error polynomial fitting coefficient, b ij represents the thermal error polynomial fit bias.

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

6. The method for compensating the spatial positioning thermal error of a CNC machine tool according to claim 5, characterized in that: 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: In the formula, is a transformation matrix of the geometric error of the motion axis X-axis coordinate system relative to the machine tool coordinate system; Indicates the X-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the Y-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the Z-direction position error of the moving axis X-axis under the current temperature coordinate state; Indicates the X-direction angle error of the moving axis X-axis under the current temperature coordinate state; Indicates the Y-direction angle error of the moving axis X-axis under the current temperature coordinate state; Indicates the Z-direction angle error of the moving axis X-axis under the current temperature coordinate state.

7. The method for compensating the spatial positioning thermal error of a CNC machine tool according to claim 6, characterized in that: The process of generating the X-direction position error of the moving axis X-axis under the current temperature coordinate state includes: In the formula, is the geometric error term, E is the error term of the X axis of the motion axis XX The sensitivity coefficient, T i (t) represents the reading of the ith temperature sensor at time t, k ij represents the thermal error polynomial fitting coefficient, b ij represents the thermal error polynomial fit bias, E XX (X) is the X-axis error term of the motion axis.

8. The method for compensating thermal errors of CNC machine tools according to claim 1, characterized in that: The step S2 comprises: Step S21: configuring different ambient temperatures and working conditions for the machine tool to be compensated, and collecting actual positioning errors of the end of the machine tool respectively; Step S22: Optimizing 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 output as the optimization model.

9. The method for compensating thermal errors of CNC machine tools in spatial positioning according to claim 1, characterized in that: The step S3 comprises: Step S31: constructing a compensation table corresponding to the error terms of each motion axis 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 for the spatial positioning parameters of the machine tool to be compensated.

10. A five-axis machine tool, characterized in that: The five-axis machine tool includes a control device, and the control device includes a processor and a memory; The memory stores computer instructions. When the processor executes the computer instructions, the method for compensating for thermal errors in spatial positioning of a CNC machine tool as described in any one of claims 1 to 9 is performed on the five-axis machine tool.

Images