Gantry machine tool thermal error compensation method, device, equipment and readable storage medium

Abstract

This disclosure relates to the field of machining technology, and proposes a method, device, equipment, and readable storage medium for thermal error compensation of a gantry milling machine. The method includes: determining the reference thermal deformation history data of the target gantry milling machine along the X-axis using a finite element simulation model of the target gantry milling machine and reference thermal boundary conditions; determining the heat-sensitive test points of the target gantry milling machine based on the reference thermal deformation history data, and acquiring the test temperature data of the heat-sensitive test points; correcting the reference thermal deformation history data using the test temperature data to generate target thermal deformation history data; and determining the target thermal error compensation model of the target gantry milling machine along the X-axis in segments using the target thermal deformation history data and preset segmentation points. The target thermal error compensation model is determined based on a multi-segment linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed. The technical solutions provided by one or more embodiments of this disclosure can improve the accuracy of thermal error compensation for gantry milling machines.

Description

Technical Field

[0001] This disclosure relates to the field of machining technology, specifically to a method, apparatus, equipment, and readable storage medium for thermal error compensation of a gantry milling machine. Background Technology

[0002] A gantry milling machine is a large CNC machining equipment, typically with a "gate"-shaped structure. It consists of main components such as a crossbeam, column, and worktable, and features high rigidity, long stroke, and strong load-bearing capacity. It is widely used in the machining of complex parts in aerospace, shipbuilding, and energy equipment industries. In the motion system of a gantry milling machine, each moving axis is usually defined according to internationally accepted standards. The "X-axis," as one of the key motion axes of a gantry milling machine, specifically refers to the main long-distance horizontal movement axis of the spindle or workpiece; its positioning accuracy directly determines the machining quality of the workpiece. Furthermore, "X-axis" is a technical term and usually does not require translation into Chinese.

[0003] During machining, heat sources such as motors, guide rails, and lead screws generate heat, and ambient temperature fluctuations can cause uneven thermal deformation of the machine tool structure, leading to a deviation between the actual relative position of the tool and the workpiece and its theoretical position. This geometric deviation caused by temperature changes can be called thermal error. Thermal error is one of the main factors affecting machine tool accuracy, especially in large-stroke equipment such as gantry milling machines. Due to the large range of motion and complex heat source distribution, the X-axis's thermally induced deformation is prone to nonlinear and time-varying characteristics, becoming a key bottleneck restricting the improvement of machining accuracy.

[0004] To suppress the impact of thermal errors, the industry typically employs thermal error compensation technology. This involves monitoring temperature or displacement changes using sensors and establishing a mathematical model between the thermal error and temperature or time. After predicting the error value in real time within the CNC system, the thermal error can be offset by software through methods such as instruction correction. However, the modeling process of traditional thermal error compensation methods relies heavily on experimental data, resulting in problems such as long modeling cycles, weak anti-interference capabilities, and insufficient model generalization. For the X-axis of long-stroke gantry milling machines, the complex error patterns make it difficult for traditional thermal error compensation methods to achieve stable and reliable compensation effects. Summary of the Invention

[0005] In view of this, one or more embodiments of this disclosure provide a method, apparatus, device and readable storage medium for thermal error compensation of a gantry milling machine, which can improve the accuracy and reliability of thermal error compensation of the gantry milling machine.

[0006] In a first aspect, this disclosure provides a thermal error compensation method for a gantry milling machine. The method includes: determining the reference thermal deformation history data of the target gantry milling machine along the X-axis using a finite element simulation model of the target gantry milling machine and reference thermal boundary conditions; determining the heat-sensitive test points of the target gantry milling machine based on the reference thermal deformation history data and acquiring the test temperature data of the heat-sensitive test points; correcting the reference thermal deformation history data using the test temperature data to generate target thermal deformation history data; and determining the target thermal error compensation model of the target gantry milling machine along the X-axis in segments using the target thermal deformation history data and preset segmentation points, wherein the preset segmentation points characterize the temperature difference between the lead screw nut and the machine bed, and the target thermal error compensation model is determined based on a multi-segment linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed.

[0007] Secondly, this disclosure provides a thermal error compensation device for a gantry milling machine. The device includes: a simulation analysis unit, used to determine the reference thermal deformation history data of the target gantry milling machine along the X-axis using a finite element simulation model of the target gantry milling machine and reference thermal boundary conditions; a test analysis unit, used to determine the heat-sensitive test points of the target gantry milling machine based on the reference thermal deformation history data, and to acquire the test temperature data of the heat-sensitive test points; a data correction unit, used to correct the reference thermal deformation history data using the test temperature data, and generate target thermal deformation history data; and an error compensation unit, used to determine the target thermal error compensation model of the target gantry milling machine along the X-axis in segments using the target thermal deformation history data and preset division points, wherein the preset division points characterize the temperature difference between the lead screw nut and the machine bed, and the target thermal error compensation model is determined based on a multi-segment linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed.

[0008] Thirdly, this disclosure provides an electronic device, which includes a memory and a processor. The memory is used to store a computer program, and when the computer program is executed by the processor, it implements the above-described thermal error compensation method for a gantry milling machine.

[0009] Fourthly, this disclosure provides a computer-readable storage medium for storing a computer program that, when executed by a processor, implements the above-described thermal error compensation method for a gantry milling machine.

[0010] This disclosure provides a technical solution through one or more embodiments, which effectively combines the simulated baseline thermal deformation history data with test temperature data to generate target thermal deformation history data for subsequent calculation of the target thermal error compensation model. Accurate target thermal deformation history data can be obtained with only a small amount of experimental test data. This method not only improves the thermal error compensation effect but also reduces the need for experimental data, lowers dependence on environmental factors, and improves the accuracy and reliability of the thermal error compensation model.

[0011] The technical solution provided by one or more embodiments of this disclosure accurately predicts and compensates for thermal errors by establishing a segmented thermal error compensation model, avoiding the need to continuously adjust and optimize the thermal error model parameters. This greatly simplifies the operation process and reduces the complexity and difficulty of operation.

[0012] The technical solutions provided by one or more embodiments of this disclosure predict and compensate for thermal errors by establishing a segmented thermal error compensation model. This model can provide a suitable thermal error compensation model based on different temperature changes in the gantry machining center, thus exhibiting good robustness. Furthermore, it can significantly improve the machining accuracy and quality of the gantry machining center. Attached Figure Description

[0013] The features and advantages of the embodiments of this disclosure will be more clearly understood by referring to the accompanying drawings, which are illustrative and should not be construed as limiting the present disclosure in any way. In the drawings: Figure 1 A schematic diagram illustrating the steps of a thermal error compensation method for a gantry milling machine in one embodiment of this disclosure is shown. Figure 2 A schematic diagram of a finite element simulation model of a target gantry milling machine is shown in one embodiment of this disclosure; Figure 3 A comparative schematic diagram of lead screw temperature rise data in one embodiment of this disclosure is shown; Figure 4 A comparative schematic diagram showing the thermal elongation error data of the lead screw in one embodiment of this disclosure is shown; Figure 5 This illustration shows a schematic diagram of the thermal error of a target gantry milling machine before compensation by the target thermal error compensation model in one embodiment of this disclosure; Figure 6 This illustration shows a schematic diagram of the thermal error of a target gantry milling machine after compensation by a target thermal error compensation model in one embodiment of this disclosure; Figure 7 A schematic diagram of the functional modules of a thermal error compensation device for a gantry milling machine in one embodiment of this disclosure is shown. Figure 8 A schematic diagram of the structure of an electronic device according to one embodiment of the present disclosure is shown. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0015] In related technologies, gantry milling machines may possess complex structural characteristics such as long stroke, lead screw pre-tension, and fixed ends on the lead screw, leading to extremely complex error patterns in X-axis thermal error. Therefore, existing thermal error compensation methods are ineffective in practice. On one hand, existing methods require extensive experimental data to establish mathematical models, which is not only time-consuming and labor-intensive but also easily affected by environmental factors, resulting in insufficient accuracy and reliability of the mathematical models. On the other hand, in practical applications, existing thermal error compensation methods typically require continuous adjustment and optimization of model parameters to achieve relatively satisfactory compensation results, significantly increasing the complexity and difficulty of operation.

[0016] In view of this, the thermal error compensation method for gantry milling machines provided by one or more embodiments of this disclosure not only solves the drawback of existing thermal compensation methods requiring a large amount of experimental data to establish a mathematical model, but also solves the drawback of existing thermal compensation methods requiring frequent adjustment and optimization of thermal error model parameters.

[0017] The thermal error compensation method for gantry milling machines provided in one or more embodiments of this disclosure can greatly reduce machining defects and scrap rates caused by thermal errors by accurately predicting and compensating for thermal errors, effectively improving the precision and quality of machine tool machining, thereby improving the production efficiency and economic benefits of machining.

[0018] Please see Figure 1 The present disclosure provides a method for thermal error compensation of a gantry milling machine, which may include the following steps.

[0019] S1: Using the finite element simulation model and reference thermal boundary conditions of the target gantry machine tool, determine the reference thermal deformation history data of the target gantry machine tool along the X-axis.

[0020] In this embodiment, by creating a finite element simulation model of the target gantry milling machine and setting the reference thermal boundary conditions of the target gantry milling machine (i.e., the standardized thermal load borne by the machine tool under preset working conditions and environment, which may include the heat generation rate of key heat sources such as the spindle, guide rails, and motor, ambient temperature, and convective heat transfer coefficient), the reference thermal deformation history data of the machine tool in the X-axis direction can be simulated. The reference thermal deformation history data refers to the continuous curve or sequence of the thermal displacement of the machine tool structure in the X-axis direction over time under continuous thermal action. The reference thermal deformation history data can reflect the dynamic evolution characteristics of the X-axis thermal deformation of the machine tool from its initial state to thermal equilibrium, and can serve as a benchmark reference for evaluating the thermal accuracy of the machine tool and for performing thermal error compensation.

[0021] In this embodiment, the baseline thermal boundary condition refers to a set of standardized and representative thermal input parameters set for simulation analysis. It typically includes parameters such as a constant ambient temperature (e.g., 25°C), the standard heating power of key heat sources (e.g., spindle, lead screw motor) at a specific idle speed, and a preset convective heat transfer coefficient. The core purpose of setting the baseline thermal boundary condition is to establish a unified and reproducible evaluation benchmark for the thermal deformation analysis of the same or different machine tools, thereby ensuring the comparability and consistency of simulation results.

[0022] In some implementations, determining the reference thermal deformation history data of the target gantry milling machine along the X-axis using the finite element simulation model and reference thermal boundary conditions of the target gantry milling machine includes: establishing the finite element simulation model containing multiple target machine tool components based on the static physical structure of the target gantry milling machine; calculating the transient thermal analysis data of each target machine tool component based on the thermodynamic modeling of each target machine tool component; and importing the transient thermal analysis data into the finite element simulation model to determine the reference thermal deformation history data.

[0023] Specifically, based on the static physical structure of the target gantry milling machine (including the geometric features of components and their connection relationships), the structural characteristics of the target gantry milling machine can be simulated with high fidelity, thereby ensuring that the thermal deformation behavior predicted by the simulation has high physical realism and accuracy, providing a reliable structural foundation for subsequent thermal characteristic analysis and thermal error compensation. Transient thermal analysis data based on thermodynamic modeling can analyze the temperature field of the machine tool under operating conditions, as well as the heat generation and heat transfer of each component. By importing the transient thermal analysis data into the finite element simulation model in a shared manner, the thermal distribution history data of the machine tool components obtained from the transient thermal analysis over time can be transformed into thermal deformation history data of the machine tool components over time.

[0024] In some embodiments, establishing the finite element simulation model containing multiple target machine tool components based on the static physical structure of the target gantry milling machine includes: establishing component simulation models of the target machine tool components; setting component connection relationships of the target machine tool components; setting structural boundary conditions of the target gantry milling machine; and establishing the finite element simulation model based on the component simulation models, the component connection relationships, and the structural boundary conditions.

[0025] Specifically, please refer to Figure 2 The component simulation model can include, but is not limited to, simulation results of components such as the machine bed, motor housing, bearing housing, bearing, motor, guide rail, slider, lead screw, lead screw nut, lead screw socket, and worktable. Structural boundary conditions can include, but are not limited to, applying pre-tension to the lead screw and applying fixed constraints to the machine bed's anchor bolt holes. Component connection relationships can include, but are not limited to: a bonded connection between the machine bed and bearing housing, motor housing, and guide rail; frictional contact between bearing housings and bearings; a non-separating connection between the guide rail and slider; a bonded connection between the slider and worktable; a bonded connection between the worktable and lead screw socket; a bonded connection between the lead screw socket and lead screw nut; and a bonded connection between the lead screw nut and lead screw rod.

[0026] In some embodiments, the calculation of transient thermal analysis data for each of the target machine tool components based on thermodynamic modeling includes at least one of the following: calculating the bearing heat load based on the total bearing friction torque and bearing speed; calculating the guide rail and slider heat load based on the dynamic friction coefficient, friction surface load, and relative motion speed between the guide rail and slider; calculating the lead screw and nut heat load based on the lead screw motor speed and the total friction torque of the lead screw and nut; calculating the air natural convection heat transfer load based on a first Nusselt number, fluid thermal conductivity coefficient, and fixed dimensions, wherein the first Nusselt number is determined based on the Grashof number, Prandtl number, heat transfer surface shape, and air flow state; and calculating the air forced convection heat transfer load based on a second Nusselt number, fluid thermal conductivity coefficient, and fixed dimensions, wherein the second Nusselt number is determined based on the Reynolds number of the rotating shaft and the Prandtl number.

[0027] In a practical application example, the thermal load generated by the bearing is theoretically calculated according to the following formula: ; In the formula, M is the total frictional torque of the bearing, in N·m; n is the bearing speed, in r / min.

[0028] In a practical application example, the thermal load generated by the guide rail and slider is theoretically calculated according to the following formula: ; In the formula, μ is the coefficient of kinetic friction; F is the load on the friction surface, in N; and v is the relative speed between the guide rail and the slider, in m / s.

[0029] In a practical application example, the thermal load generated by the lead screw and nut is theoretically calculated according to the following formula: ; In the formula, n is the speed of the lead screw motor; M is the total frictional torque of the lead screw and nut pair.

[0030] In a practical application example, the natural convection heat transfer load of air is theoretically calculated according to the following formula: ; ; ; ; In the formula, h is the convective heat transfer coefficient; The first Nuschelt number; L is the standard dimension in meters; Gr is the Grashof number; Pr is the Prandtl number; g is the acceleration due to gravity in meters. 2 / s;a v The coefficient of volumetric expansion of air, expressed in cubic centimeters (C). -1 △T is the temperature difference between the structural surface and the ambient temperature, in °C; ν is the kinematic viscosity of air, in mm. 2 / s;c p ρ is the isobaric specific heat capacity of air, expressed in J / kg·°C; ρ is the density of air, expressed in kg / m³. 3 ; k is the thermal conductivity coefficient of the fluid, with units of W / (m2·°C); the values ​​of C and n are related to the shape of the heat transfer surface and the air flow state.

[0031] In a practical application example, the forced air convection heat transfer load is theoretically calculated according to the following formula: ; ; ; In the formula, is the second Nusselt number; Re is the Reynolds number of the rotation axis; Pr is the Prandtl number, the formula of which can be found in the previous application example; w The angular velocity of the lever axis is expressed in rad / s. d 0 represents the nominal diameter of the lead screw shaft; The kinematic viscosity of air is expressed in cst.

[0032] S2: Based on the reference thermal deformation history data, determine the thermally sensitive test points of the target gantry milling machine and obtain the test temperature data of the thermally sensitive test points.

[0033] In this embodiment, the simulated baseline thermal deformation history data can qualitatively reflect the thermal change characteristics of different locations on the target gantry milling machine. However, since the baseline thermal deformation history data is determined by baseline thermal boundary conditions, there are numerical differences between this data and the thermal boundary conditions in actual machine tool application. Therefore, by acquiring test temperature data from some heat-sensitive test points, the theoretical baseline thermal deformation history data can be corrected to target thermal deformation history data that highly conforms to actual working conditions using a small amount of experimental test data. Furthermore, the baseline thermal deformation history data also provides guidance for the arrangement of temperature measurement points during thermal error testing.

[0034] In some implementations, determining the heat-sensitive test points of the target gantry milling machine based on the reference thermal deformation history data includes: for each candidate test point of the target gantry milling machine, calculating the candidate correlation between temperature rise data and thermal error change law based on the reference thermal deformation history data; and determining a preset number of heat-sensitive test points from the candidate test points based on the magnitude of the candidate correlation.

[0035] Specifically, candidate test points are locations on the target gantry milling machine where temperature sensors can be placed. Based on the baseline thermal deformation history data obtained from simulation, the temperature rise data of different candidate test points on the target gantry milling machine can be examined, and correlation calculations can be performed with the thermal error variation law to screen out several heat-sensitive test points with high correlation to thermal error. For example, the thermal error of the X-axis moving parts of the target gantry milling machine in the X direction is mainly caused by the thermal deformation of the leadscrew in the X direction. Therefore, extracting the X-axis thermal deformation data of multiple heat-sensitive test points on the leadscrew can represent the thermal deformation data of the X-axis moving parts in the X direction.

[0036] S3: Using the test temperature data, correct the reference thermal deformation history data to generate the target thermal deformation history data.

[0037] In this embodiment, by arranging heat-sensitive test points on an actual machine tool, measured temperature data of key locations under real operating conditions can be obtained. Comparing and analyzing these measured temperature data with the baseline thermal boundary conditions used in the simulation allows for the identification and quantification of numerical differences. Subsequently, based on these numerical differences, correction relationships or coefficients are established to scale and adjust the simulated baseline thermal deformation history data, ultimately generating target thermal deformation history data that highly matches the actual thermal state of the machine tool.

[0038] In some implementations, the step of using the test temperature data to correct the reference thermal deformation history data and generate target thermal deformation history data includes: using the test temperature data to correct the reference thermal boundary conditions to obtain target thermal boundary conditions; and using the finite element simulation model and the target thermal boundary conditions to determine the target thermal deformation history data.

[0039] Specifically, by comparing the actual temperature data at the temperature test points with the simulated temperature field, key parameters in the baseline thermal boundary conditions (such as convective heat transfer coefficient, heat source power, or ambient temperature) can be adjusted in reverse, ensuring that the generated simulated temperature field replicates the measured results. The essence of this step is to establish a "target thermal boundary condition" that conforms to the physical world, replacing the original theoretical or empirical assumptions. Subsequently, this modified target thermal boundary condition is input into a pre-established and verified finite element simulation model. Running the model again for calculation, the thermal input used in the simulation now closely approximates real-world conditions, resulting in more accurate "target thermal deformation history data." The core advantage of this method is that it calibrates the input source of the entire simulation system using a small amount of measured data, thereby giving the system's predicted output higher engineering reliability.

[0040] In some practical experiments, by organizing and analyzing simulation data and thermal error test data, conclusions can be drawn that the simulation and experiment show a high degree of consistency. For example, please refer to... Figure 3 and Figure 4 The data includes the temperature rise and thermal expansion error of the leadscrew when the X-axis moving component is in the middle position in a practical application example. The data analysis shows that the finite element method can effectively simulate the thermal deformation of the X-axis in a gantry machining center, thereby predicting the generation and trend of thermal errors. Therefore, when testing the thermal errors of other machine models, thermal simulation analysis can be used first to predict the structural thermal deformation law, and then appropriate temperature measurement points can be selected to correct the baseline thermal deformation history data, in order to better compensate for thermal errors.

[0041] S4: Using the target thermal deformation history data and preset segmentation points, the target thermal error compensation model of the target gantry machine tool on the X-axis is determined in segments. The preset segmentation points represent the temperature difference between the lead screw nut and the machine bed. The target thermal error compensation model is determined based on a multi-segment linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed.

[0042] In this embodiment, when organizing and analyzing the thermal error test data, it was found that the thermal error variation pattern is usually not linear. If a linear compensation model is used to match the thermal error variation pattern, its compensation effect is limited. Therefore, this disclosure considers using a piecewise compensation model to better reflect the authenticity of the thermal error variation pattern and improve the thermal error compensation effect.

[0043] In this embodiment, through extensive experimental research, this disclosure has found that the thermal error variation law is related to the temperature difference between the lead screw nut and the bed temperature (temperature difference = lead screw nut temperature - bed temperature). Therefore, some special temperature differences between the lead screw nut and the bed are determined as preset dividing points to segment the target thermal error compensation model, thereby improving the accuracy and reliability of the target thermal error compensation model.

[0044] In this embodiment, the thermal expansion of the bed (workpiece side) and the thermal expansion of the leadscrew nut (tool side) generally have some offsetting effects. Therefore, in each segment, the linear combination of the temperature change of the leadscrew nut and the temperature change of the bed accurately describes the thermally induced changes in the relative position between the tool and the workpiece, rather than viewing the deformation of a single component in isolation.

[0045] In some implementations, a thermal error compensation program can be written into the gantry machining center. After monitoring the temperature changes at the test points of the gantry machining center in real time through temperature sensors, the current segmented thermal error compensation model can be automatically solved, and the compensation amount can be automatically adjusted to perform thermal error compensation.

[0046] In some embodiments, the step of using the target thermal deformation history data and preset division points to segmentally determine the target thermal error compensation model of the target gantry machine tool on the X-axis includes: if the temperature difference between the lead screw nut and the machine bed in the target thermal deformation history data is located between the first division point and the second division point, then a first linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed is determined based on the target thermal deformation history data; if the temperature difference between the lead screw nut and the machine bed in the target thermal deformation history data is located between the second division point and the third division point, then a second linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed is determined based on the target thermal deformation history data.

[0047] Specifically, the segment between the first and second segmentation points constitutes a target thermal error compensation model, where the thermal error pattern can be approximated as linear for numerical solution. Similarly, the segment between the second and third segmentation points constitutes another target thermal error compensation model, where the thermal error pattern can also be approximated as linear for numerical solution. With pre-set reasonable segmentation points, the accuracy of each segment of the target thermal error compensation model can be fully guaranteed, and the overall computational complexity of the model is controllable. Thus, compared to a simple overall linear compensation model, a target thermal error compensation model formed by combining multiple segments can better fit the thermal error pattern. For example, compared to fitting a target curve with a single line segment, the combination of multiple line segments obviously provides a better fit to the curve.

[0048] In a practical application example, the three mathematical expressions of the target thermal error compensation model are as follows: ΔE1=A1·ΔT 丝杠螺母 –B1·ΔT 床身 , 0 < ΔT 差值 ≤T1; ΔE2=A2·ΔT 丝杠螺母 –B2·ΔT 床身 T1 < ΔT 差值 ≤T2; ΔE3=A3·ΔT 丝杠螺母 –B3·ΔT 床身 T2 < ΔT 差值 ≤T3; Where ΔE1, ΔE2, and ΔE3 are thermal error compensation quantities, and ΔT 差值 The temperature difference between the lead screw nut and the machine bed is represented by T1, T2, and T3, which are three dividing points. ΔT 丝杠螺母 The change in temperature of the lead screw nut is ΔT. 床身 The change in bed temperature is represented by A1, A2, A3, B1, B2, and B3, which are linear coefficients that can be obtained from the analysis of test data (e.g., by least squares fitting).

[0049] In this practical application example, the three-segment target thermal error compensation model is used to conduct thermal error compensation tests on the machine tool. The error before compensation can be found in [reference needed]. Figure 5 The compensated error can be found in [reference]. Figure 6 The final compensation effect reached approximately 50%.

[0050] This disclosure provides a technical solution through one or more embodiments, which effectively combines the simulated baseline thermal deformation history data with test temperature data to generate target thermal deformation history data for subsequent calculation of the target thermal error compensation model. Accurate target thermal deformation history data can be obtained with only a small amount of experimental test data. This method not only improves the thermal error compensation effect but also reduces the need for experimental data, lowers dependence on environmental factors, and improves the accuracy and reliability of the thermal error compensation model.

[0051] The technical solution provided by one or more embodiments of this disclosure accurately predicts and compensates for thermal errors by establishing a segmented thermal error compensation model, avoiding the need to continuously adjust and optimize the thermal error model parameters. This greatly simplifies the operation process and reduces the complexity and difficulty of operation.

[0052] The technical solutions provided by one or more embodiments of this disclosure predict and compensate for thermal errors by establishing a segmented thermal error compensation model. This model can provide a suitable thermal error compensation model based on different temperature changes in the gantry machining center, thus exhibiting good robustness. Furthermore, it can significantly improve the machining accuracy and quality of the gantry machining center.

[0053] Please see Figure 7 This disclosure also provides a thermal error compensation device for a gantry milling machine, the device comprising: The simulation analysis unit 100 is used to determine the reference thermal deformation history data of the target gantry machine tool in the X-axis by using the finite element simulation model and reference thermal boundary conditions of the target gantry machine tool. The test analysis unit 200 is used to determine the heat-sensitive test points of the target gantry milling machine based on the reference thermal deformation history data, and to acquire the test temperature data of the heat-sensitive test points. The data correction unit 300 is used to correct the reference thermal deformation history data using the test temperature data and generate target thermal deformation history data. Error compensation unit 400 is used to determine the target thermal error compensation model of the target gantry machine tool on the X-axis in segments using the target thermal deformation history data and preset division points. The preset division points represent the temperature difference between the lead screw nut and the machine bed. The target thermal error compensation model is determined based on a multi-segment linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed.

[0054] In one embodiment, the simulation analysis unit 100 is specifically used to: establish a finite element simulation model containing multiple target machine tool components based on the static physical structure of the target gantry machine tool; calculate the transient thermal analysis data of each target machine tool component based on the thermodynamic modeling of each target machine tool component; and import the transient thermal analysis data into the finite element simulation model to determine the reference thermal deformation history data.

[0055] In one embodiment, the simulation analysis unit 100 includes a simulation modeling subunit, which is specifically used for: establishing a component simulation model of the target machine tool component; setting the component connection relationship of the target machine tool component; setting the structural boundary conditions of the target gantry milling machine; and establishing the finite element simulation model based on the component simulation model, the component connection relationship, and the structural boundary conditions.

[0056] In one embodiment, the simulation analysis unit 100 includes a thermal analysis subunit, which is specifically used for: calculating the bearing heat load based on the total bearing friction torque and bearing speed; calculating the guide rail and slider heat load based on the dynamic friction coefficient, friction surface load, and relative motion speed between the guide rail and slider; calculating the lead screw and nut heat load based on the lead screw motor speed and the total friction torque of the lead screw nut; calculating the air natural convection heat transfer load based on a first Nusselt number, fluid thermal conductivity coefficient, and fixed dimensions, wherein the first Nusselt number is determined based on the Grashof number, Prandtl number, heat transfer surface shape, and air flow state; and calculating the air forced convection heat transfer load based on a second Nusselt number, fluid thermal conductivity coefficient, and fixed dimensions, wherein the second Nusselt number is determined based on the rotating shaft Reynolds number and the Prandtl number.

[0057] In one embodiment, the test analysis unit 200 is further configured to: calculate, for each candidate test point of the target gantry milling machine, a candidate correlation between the temperature rise data and the thermal error change law based on the reference thermal deformation history data; and determine a preset number of the heat-sensitive test points among the candidate test points based on the magnitude of the candidate correlation.

[0058] In one embodiment, the data correction unit 300 is specifically used to: correct the reference thermal boundary conditions using the test temperature data to obtain the target thermal boundary conditions; and determine the target thermal deformation history data using the finite element simulation model and the target thermal boundary conditions.

[0059] In one embodiment, the error compensation unit 400 is specifically used to: if the temperature difference between the lead screw nut and the bed is located between the first and second dividing points in the target thermal deformation history data, then determine a first linear combination of the temperature change of the lead screw nut and the temperature change of the bed based on the target thermal deformation history data; if the temperature difference between the lead screw nut and the bed is located between the second and third dividing points in the target thermal deformation history data, then determine a second linear combination of the temperature change of the lead screw nut and the temperature change of the bed based on the target thermal deformation history data.

[0060] The various units described in the above embodiments can be implemented by a computer chip or by a product with a certain function. A typical implementation device is a computer. Specifically, the computer can be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smartphone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or any combination of these devices.

[0061] For ease of description, the above devices are described separately by function as various units. Of course, in implementing this application, the functions of each unit can be implemented in one or more software and / or hardware.

[0062] Please see Figure 8 This disclosure also provides an electronic device, which includes a memory and a processor. The memory is used to store a computer program, and when the computer program is executed by the processor, it implements the above-described thermal error compensation method for a gantry milling machine.

[0063] This disclosure also provides a computer-readable storage medium for storing a computer program that, when executed by a processor, implements the above-described thermal error compensation method for a gantry milling machine.

[0064] The processor can be a central processing unit (CPU). It can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations thereof.

[0065] Memory, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the methods in the embodiments of this disclosure. The processor executes various functional applications and data processing by running the non-transitory software programs, instructions, and modules stored in the memory, thereby implementing the methods in the above-described embodiments.

[0066] The memory may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created by the processor, etc. Furthermore, the memory may include high-speed random access memory and non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory may optionally include memory remotely located relative to the processor, which can be connected to the processor via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0067] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0068] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, embodiments of apparatus, devices, and storage media are basically similar to method embodiments, so the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0069] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

[0070] Although embodiments of the present disclosure have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present disclosure, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for thermal error compensation of a gantry milling machine, characterized in that, The method includes: Using the finite element simulation model and reference thermal boundary conditions of the target gantry milling machine, the reference thermal deformation history data of the target gantry milling machine along the X-axis are determined; Based on the reference thermal deformation history data, determine the thermally sensitive test points of the target gantry milling machine and obtain the test temperature data of the thermally sensitive test points; Using the test temperature data, the reference thermal deformation history data is corrected to generate the target thermal deformation history data; Using the target thermal deformation history data and preset segmentation points, the target thermal error compensation model of the target gantry machine tool on the X-axis is determined in segments. The preset segmentation points represent the temperature difference between the lead screw nut and the machine bed. The target thermal error compensation model is determined based on a multi-segment linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed.

2. The method according to claim 1, characterized in that, The determination of the reference thermal deformation history data of the target gantry milling machine along the X-axis using the finite element simulation model and reference thermal boundary conditions of the target gantry milling machine includes: Based on the static physical structure of the target gantry milling machine, a finite element simulation model containing multiple target machine tool components is established; Based on the thermodynamic modeling of each of the target machine tool components, the transient thermal analysis data of each of the target machine tool components are calculated; The transient thermal analysis data is imported into the finite element simulation model to determine the baseline thermal deformation history data.

3. The method according to claim 2, characterized in that, The step of establishing a finite element simulation model containing multiple target machine tool components based on the static physical structure of the target gantry milling machine includes: Establish a component simulation model of the target machine tool component; Configure the component connection relationships of the target machine tool components; Set the structural boundary conditions for the target gantry milling machine; The finite element simulation model is established based on the component simulation model, the component connection relationship, and the structural boundary conditions.

4. The method according to claim 2, characterized in that, The calculation of transient thermal analysis data for each of the target machine tool components based on thermodynamic modeling includes at least one of the following: Calculate the bearing heat load based on the total frictional torque and bearing speed; Calculate the thermal load on the guide rail and slider based on the coefficient of dynamic friction between the guide rail and slider, the load on the friction surface and the relative motion speed. Calculate the thermal load generated by the lead screw and nut based on the speed of the lead screw motor and the total frictional torque of the lead screw and nut; The natural convection heat transfer load of air is calculated based on the first Nusselt number, the fluid thermal conductivity coefficient, and the fixed dimensions. The first Nusselt number is determined according to the Grashof number, Prandtl number, heat transfer surface shape, and air flow state. The forced convection heat transfer load of air is calculated based on the second Nusselt number, the fluid thermal conductivity, and the fixed dimensions. The second Nusselt number is determined based on the Reynolds number of the rotating shaft and the Prandtl number.

5. The method according to claim 1, characterized in that, The step of determining the thermally sensitive test points of the target gantry milling machine based on the reference thermal deformation history data includes: For each candidate test point of the target gantry milling machine, based on the reference thermal deformation history data, the candidate correlation between the temperature rise data and the thermal error change law is calculated. Based on the numerical value of the candidate correlation, a preset number of the heat-sensitive test points are determined from the candidate test points.

6. The method according to claim 1, characterized in that, The step of using the test temperature data to correct the reference thermal deformation history data and generate target thermal deformation history data includes: Using the test temperature data, the reference thermal boundary conditions are corrected to obtain the target thermal boundary conditions; The thermal deformation history data of the target are determined using the finite element simulation model and the target thermal boundary conditions.

7. The method according to claim 1, characterized in that, The step of using the target thermal deformation history data and preset segmentation points to segmentally determine the target thermal error compensation model of the target gantry milling machine on the X-axis includes: If the temperature difference between the lead screw nut and the bed is located between the first and second dividing points in the target thermal deformation history data, then a first linear combination of the temperature change of the lead screw nut and the temperature change of the bed is determined based on the target thermal deformation history data. If the temperature difference between the lead screw nut and the bed is located between the second and third dividing points in the target thermal deformation history data, then a second linear combination of the temperature change of the lead screw nut and the temperature change of the bed is determined based on the target thermal deformation history data.

8. A thermal error compensation device for a gantry milling machine, characterized in that, The device includes: The simulation analysis unit is used to determine the reference thermal deformation history data of the target gantry milling machine in the X-axis by using the finite element simulation model and reference thermal boundary conditions of the target gantry milling machine. The test analysis unit is used to determine the heat-sensitive test points of the target gantry milling machine based on the reference thermal deformation history data, and to acquire the test temperature data of the heat-sensitive test points. The data correction unit is used to correct the reference thermal deformation history data using the test temperature data and generate target thermal deformation history data. The error compensation unit is used to determine the target thermal error compensation model of the target gantry machine tool on the X-axis in segments using the target thermal deformation history data and preset division points. The preset division points represent the temperature difference between the lead screw nut and the machine bed. The target thermal error compensation model is determined based on a multi-segment linear combination of the temperature change of the lead screw nut and the temperature change of the machine bed.

9. An electronic device, characterized in that, The electronic device includes a memory and a processor, the memory being used to store a computer program that, when executed by the processor, implements the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store a computer program that, when executed by a processor, implements the method as described in any one of claims 1 to 7.

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