Numerical control machine tool optimization design method and device, electronic equipment and storage medium

Abstract

The application provides a numerical control machine tool optimization design method and device, electronic equipment and storage medium, belongs to numerical control machine tool optimization design technical field, method includes constructing the dynamic model of numerical control machine tool, dynamic model includes numerical control machine tool main body, tool and workpiece;The transient dynamic characteristic analysis is carried out to the dynamic model, and the start-stop impact characteristic curve of the tool tip and the workpiece is obtained;According to the start-stop impact characteristic curve, whether the dynamic error curve of the tool tip relative to the workpiece satisfies the preset dynamic error index is judged, if not, the modal analysis is carried out to the numerical control machine tool main body according to the frequency domain characteristic curve of the start-stop impact characteristic curve, the weak link of the numerical control machine tool main body is determined and optimized, until the dynamic error index is satisfied.The dynamic error of numerical control machine tool is characterized by the dynamic error curve of tool tip relative to workpiece, the dynamic characteristics of numerical control machine tool can be more accurately evaluated, and high-precision machining of numerical control machine tool is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optimal design of numerical control machine tools, and particularly relates to a numerical control machine tool optimal design method and device, electronic equipment and a storage medium. BACKGROUND

[0002] With the increasing demand for precision and ultra-precision machining of numerical control machine tools in the manufacturing industry, the influence of dynamic error factors on the spatial positioning accuracy of numerical control machine tools is also more and more obvious. The machining accuracy of the numerical control machine tool determines the product quality of the machined workpiece, and improving the dynamic characteristics of the numerical control machine tool is an important aspect of improving the machining accuracy of the numerical control machine tool. In order to achieve high-precision machining of the numerical control machine tool, it is necessary to ensure that the numerical control machine tool has a small enough dynamic error. At present, in the research on the dynamic optimization design of numerical control machine tools, the target of dynamic characteristic analysis is still mainly to obtain modal and stiffness. Modal is used to reflect the dynamic response characteristics of the structure of the numerical control machine tool, and stiffness is used to reflect the anti-deformation characteristics of the structure of the numerical control machine tool. However, it cannot optimize the dynamic error generated by the numerical control machine tool in the machining stage, resulting in that the machining accuracy still needs to be improved. SUMMARY

[0003] The present application provides a numerical control machine tool optimal design method, device, electronic equipment and storage medium, which can solve the defects that the target of dynamic characteristic analysis of the existing numerical control machine tool is mainly to obtain modal and stiffness, and cannot optimize the dynamic error generated by the numerical control machine tool in the machining stage, resulting in that the machining accuracy still needs to be improved.

[0004] The present application provides a numerical control machine tool optimal design method, which comprises the following steps:

[0005] Constructing a dynamics model of the numerical control machine tool, wherein the dynamics model comprises a numerical control machine tool main body, a tool arranged on the numerical control machine tool main body, and a workpiece;

[0006] Performing transient dynamics characteristic analysis on the dynamics model to obtain a tool tip of the tool and a start-stop impact characteristic curve of the workpiece;

[0007] According to the start-stop impact characteristic curve corresponding to each of the tool tip and the workpiece, it is judged whether a dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index, and if not, modal analysis is performed on the numerical control machine tool main body according to a frequency domain characteristic curve of the start-stop impact characteristic curve to determine a weak link of the numerical control machine tool main body;

[0008] According to an optimal design scheme corresponding to the weak link, the step of constructing the dynamics model of the numerical control machine tool is returned until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

[0009] As an embodiment, the start-stop impact characteristic curve comprises a vibration decay characteristic curve, and correspondingly, the judging whether the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index comprises:

[0010] obtaining the dynamic error curve of the tool tip relative to the workpiece according to the amplitudes of the vibration decay characteristic curves of the tool tip and the workpiece at the same time node;

[0011] judging whether the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index according to the maximum amplitude of the dynamic error curve.

[0012] As an embodiment, the modal analysis of the numerical control machine tool body according to the frequency domain characteristic curve of the start-stop impact characteristic curve comprises:

[0013] determining the natural frequencies corresponding to at least one frequency domain peak value of the frequency domain characteristic curve of the start-stop impact characteristic curve;

[0014] performing modal analysis on the numerical control machine tool body to determine the vibration modes of the structural members of the numerical control machine tool body at the natural frequencies;

[0015] determining the weak links of the numerical control machine tool body according to the vibration modes of the structural members of the numerical control machine tool body at the natural frequencies.

[0016] As an embodiment, the determining the weak links of the numerical control machine tool body according to the vibration modes of the structural members of the numerical control machine tool body at the natural frequencies comprises:

[0017] determining the strain energy of the structural members of the numerical control machine tool body at the natural frequencies according to the vibration modes of the structural members of the numerical control machine tool body at the natural frequencies to construct a strain energy cloud map;

[0018] taking the structural members with strain energy reaching a preset value as the weak links of the numerical control machine tool body according to the strain energy cloud map.

[0019] As an embodiment, the constructing the dynamics model of the numerical control machine tool comprises:

[0020] determining the structural parameters and attribute parameters corresponding to the numerical control machine tool body, the tool and the workpiece respectively;

[0021] constructing the whole-machine finite element analysis model of the numerical control machine tool according to the structural parameters and attribute parameters corresponding to the numerical control machine tool body, the tool and the workpiece respectively;

[0022] The posture and constraint condition of the whole machine finite element analysis model are configured to obtain a dynamic model of the numerical control machine tool.

[0023] As an embodiment, the posture of the whole machine finite element analysis model is determined according to the position of the workpiece, and the constraint condition of the whole machine finite element analysis model is determined by the foot joint of the numerical control machine tool body.

[0024] As an embodiment, the transient dynamic characteristic analysis of the dynamic model comprises:

[0025] The load type, load application position, damping parameter, time length and step length of the transient dynamic characteristic analysis are determined;

[0026] According to the load type, load application position, damping parameter, time length and step length, uniaxial or multi-axis linkage start-stop impact characteristic analysis is performed on the dynamic model.

[0027] The application further provides a numerical control machine tool optimization design device, comprising:

[0028] A construction module is configured to construct a dynamic model of a numerical control machine tool, wherein the dynamic model comprises a numerical control machine tool body, a tool arranged on the numerical control machine tool body and a workpiece;

[0029] An analysis module is configured to perform transient dynamic characteristic analysis on the dynamic model to obtain start-stop impact characteristic curves of a tool tip of the tool and the workpiece;

[0030] A judgment module is configured to determine whether a dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index according to the respective start-stop impact characteristic curves of the tool tip and the workpiece, and if not, to perform modal analysis on the numerical control machine tool body according to frequency domain characteristic curves of the start-stop impact characteristic curves to determine a weak link of the numerical control machine tool body.

[0031] An optimization module is configured to return to the step of constructing the dynamic model of the numerical control machine tool according to an optimization design scheme corresponding to the weak link until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

[0032] The application further provides an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the numerical control machine tool optimization design method of any of the above embodiments when executing the computer program.

[0033] The application further provides a non-transitory computer readable storage medium having a computer program stored thereon, wherein the computer program is executable by a processor to implement the numerical control machine tool optimization design method of any of the above embodiments.

[0034] The numerical control machine tool optimization design method, device, electronic equipment and storage medium provided by the application perform transient dynamic characteristic analysis on a dynamic model to obtain an enable-stop impact characteristic curve of a tool tip and a workpiece, and determine whether a dynamic error curve of the tool tip relative to the workpiece in a machining stage meets a preset dynamic error index according to the enable-stop impact characteristic curve, so that the dynamic characteristics of the numerical control machine tool can be more accurately evaluated, and high-precision machining of the numerical control machine tool is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0036] Figure 1 is one of the flowcharts of the numerical control machine tool optimization design method provided by the application.

[0037] Figure 2 is the flowchart of constructing the whole machine finite element analysis model of the numerical control machine tool provided by the application.

[0038] Figure 3 a is the oscillation attenuation characteristic curve of the tool tip under the start-stop working condition of the machine tool provided by the application, Figure 3 b is the oscillation attenuation characteristic curve of the workpiece under the start-stop working condition of the machine tool provided by the application.

[0039] Figure 4 is the dynamic error curve of the tool tip relative to the workpiece provided by the application.

[0040] Figure 5 a is the Y-direction oscillation attenuation characteristic Fourier transform curve of the tool tip provided by the application, Figure 5 b is the Y-direction oscillation attenuation characteristic Fourier transform curve of the workpiece provided by the application.

[0041] Figure 6 is the schematic diagram of the optimization design scheme provided by the application.

[0042] Figure 7 is the second flowchart of the numerical control machine tool optimization design method provided by the application.

[0043] Figure 8 is the flowchart of identifying the structural weak link and improving and optimizing iteration provided by the application.

[0044] Figure 9 a- Figure 9c is a contrast chart of X, Y and Z three direction dynamic errors of the machine tool before and after optimization provided by the application.

[0045] Figure 10 is a structural schematic diagram of the numerical control machine tool optimization design device provided by the application.

[0046] Figure 11 is a structural schematic diagram of the electronic device provided by the application. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical scheme and advantages of the application clearer, the technical scheme in the application will be described clearly and completely in combination with the drawings in the application. Obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0048] It should be noted that all the actions of obtaining signals, information or data in the application are performed under the premise of complying with the corresponding data protection regulations and policies of the place and obtaining the authorization given by the owner of the corresponding device.

[0049] In actual machining process, the numerical control machine tool often has good geometric precision but insufficient machining precision, and the design personnel and process personnel of the numerical control machine tool cannot quickly and accurately find the root cause, thereby causing repeated version iteration of the numerical control machine tool, long research and development cycle, high cost and other problems. In terms of dynamic analysis and dynamic design optimization of complex mechanical structures, the finite element method has become the mainstream of dynamic analysis of numerical control machine tools. By using simulation technology, the dynamic error of the whole machine can be predicted and evaluated in the early stage of design of the numerical control machine tool, the weak link of the numerical control machine tool can be found in time and optimized and improved, the design quality of the product can be effectively improved, and then the machining quality can be ensured and the product research and development cycle can be shortened.

[0050] However, in the current research on dynamic optimization design of numerical control machine tools, the target of dynamic characteristic analysis is still mainly to obtain modal and stiffness, and little attention is paid to the problem that the dynamic error caused by start-stop impact characteristics of the numerical control machine tool causes insufficient machining precision of the workpiece, so that the dynamic characteristics of the numerical control machine tool cannot meet the needs of efficient and high-precision machining. In addition, the error of the numerical control machine tool includes static error and dynamic error, the static error includes geometric error, thermal error and assembly error, and the dynamic error is determined by mechanical dynamics characteristics and other parameters. The error of the tool tip measured by the machine tool interferometer includes static error and dynamic error, and the dynamic error caused by the mechanical structure cannot be stripped off, so it is difficult to accurately find the main factor affecting the machining precision. Although the use of grating ruler full closed loop control technology of the numerical control machine tool can ensure that the moving parts are in accurate position, it cannot ensure the position distance error between the grating ruler reading head and the tool tip and the workpiece, so that the machined workpiece surface appears defects such as concave indentation, convex ridge and characteristic size out-of-tolerance. The present application can effectively solve the distance change of the tool tip and the workpiece caused by the positive and negative impact force of the moving parts in the start-stop impact process, well compensate for the defect of the full closed loop control technology, improve the machining precision of the workpiece. The dynamic error caused by the start-stop impact of the machine tool can be quantitatively analyzed in the design stage, and the structure is optimized accordingly, so as to ensure the machining precision of the machined workpiece, and the final cutting effect can be met without multiple version iterations of the prototype in the later stage.

[0051] Figure 1 is one of the flowcharts of the numerical control machine tool optimization design method provided by the present application, as shown in Figure 1 The present application provides a numerical control machine tool optimization design method based on start-stop impact characteristics, which is suitable for optimization and improvement in the design stage or actual use process of the numerical control machine tool, and the method comprises steps S100-S400.

[0052] Step S100, a dynamic model of the numerical control machine tool is constructed, and the dynamic model comprises a numerical control machine tool main body, a tool arranged on the numerical control machine tool main body and a workpiece.

[0053] The dynamic model is preferably a finite element analysis model, which is constructed based on the finite element analysis model, is used for simulating the numerical control machine tool, and simulates the actual behavior through numerical calculation. Preferably, the present application can use the dynamic model to perform simulation test, calculate the dynamic error of the machine tool, quantitatively evaluate the dynamic precision of the machine tool, determine the structure parts causing large dynamic error, and guide the machine tool designer to optimize and improve the related parts, so as to greatly improve the dynamic error of the machine tool, improve the machining precision and surface roughness of the machined workpiece, replace the traditional large number of actual cutting tests after the completion of the prototype assembly, thereby reducing the research and development cost and various resource waste, reducing blind version iteration, and improving the market competitiveness of the machine tool.

[0054] In step S200, transient dynamic characteristic analysis is performed on the dynamic model to obtain the start-stop impact characteristic curves of the tool tip and the workpiece.

[0055] Transient dynamic characteristic analysis is used to study the dynamic response process of a structure or system under the action of rapidly changing loads over time (such as impact, explosion, vibration, sudden start-stop, etc.), and the core goal is to predict the variation law of the displacement, stress, strain, acceleration and other parameters of the structure over time. In the present application, transient dynamic characteristic analysis is performed on the dynamic model, specifically, the start-stop impact characteristics of the dynamic model are analyzed to obtain the three-dimensional start-stop impact characteristic curves of the tool tip and the workpiece under the preset working condition, three-dimensional referring to the X-axis direction, Y-axis direction and Z-axis direction in the XYZ coordinate system. The start-stop impact characteristic curves are used to evaluate the start-stop impact characteristics of the numerical control machine tool.

[0056] In step S300, whether the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index is determined according to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively. If not, modal analysis is performed on the numerical control machine tool body according to the frequency domain characteristic curves of the start-stop impact characteristic curves to determine the weak link of the numerical control machine tool body.

[0057] The dynamic error curve of the tool tip relative to the workpiece is determined based on the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively. The machining accuracy of the machine tool is closely related to the dynamic error caused by the start-stop impact characteristics of the machine tool. However, in the existing research on dynamic optimization design of machine tools, the target of dynamic characteristic analysis is still mainly to obtain modal and stiffness. The present application provides a new technical index for dynamic error evaluation of numerical control machine tools, i.e., the dynamic error of the tool tip relative to the workpiece, which solves the problem that the dynamic error caused by the start-stop impact characteristics is ignored in the previous dynamic characteristic analysis, and the machining accuracy cannot be guaranteed. In addition, the dynamic error of the tool tip relative to the workpiece is related to the mechanical structure of the numerical control machine tool, which is conducive to determining the main structural parts that affect the machining accuracy.

[0058] Optionally, the numerical control machine tool body includes a single-axis or multi-axis linkage motion shaft, which is used to drive the moving part to translate or rotate according to numerical control instructions, thereby driving the tool and the workpiece to move and / or rotate in a relative motion along a set direction at a set speed / acceleration in the XYZ coordinate system, so as to obtain a workpiece that meets the requirements. Correspondingly, the dynamic error index includes a dynamic error index under a design requirement acceleration condition, and the acceleration condition includes a rapid feed condition G00 and a cutting feed condition G01. The cutting feed condition G01 includes but is not limited to different feed speeds, spindle speeds, cutting depths and other information. The manifestation form of the dynamic error index includes but is not limited to under-cutting, over-cutting, surface vibration, and reduced positioning accuracy of the feature size of the workpiece surface.

[0059] Modal analysis is a core technology for studying the dynamic characteristics of a structure, used to determine the natural frequency, mode shape (modal shape) and damping ratio of the structure, to help understand the vibration behavior of the structure under dynamic load, to provide key basis for avoiding frequency, reducing vibration and optimization by identifying the "vibration fingerprint" (frequency and mode shape) of the structure, and modal analysis can be realized based on finite element analysis software. According to the start-stop impact characteristic curve, the modal analysis of the numerical control machine tool body is carried out, and the weak link of the numerical control machine tool body is determined, specifically, the natural frequency of the place with larger dynamic error is determined according to the start-stop impact characteristic curve, and the modal shape corresponding to the natural frequency is obtained by combining modal analysis to determine the weak link.

[0060] Step S400, according to the optimization design scheme corresponding to the weak link, return to the step of constructing the dynamic model of the numerical control machine tool, until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

[0061] According to the optimization design scheme, the dynamic model is reconstructed, and the reconstructed dynamic model is verified to determine whether it meets the design requirements. If it meets the design requirements, the optimization is completed, otherwise, steps S100-S400 are repeatedly executed until the reconstructed dynamic model meets the design requirements. In step S300, if the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index, it is determined that the dynamic model does not need to be optimized, and the process is ended.

[0062] It can be understood that the present application takes the dynamic error of the tool tip relative to the workpiece as the evaluation standard of the machining accuracy of the numerical control machine tool, provides a direct technical index to represent the dynamic error of the machine tool, can determine the dynamic error in the machining stage, and further determines the feed axis causing larger dynamic error, so as to guide the designer to optimize and improve the related parts, which is beneficial to more accurately evaluate the dynamic characteristics of the numerical control machine tool, and solves the problem that the natural frequency and dynamic stiffness are taken as the optimization target in the past dynamic characteristic analysis, the start-stop impact characteristics are ignored, and the machining accuracy cannot be guaranteed.

[0063] As an optional embodiment, the dynamic model of the numerical control machine tool comprises steps S110-S130.

[0064] Step S110, determine the structure parameters and attribute parameters corresponding to the numerical control machine tool body, the tool and the workpiece respectively.

[0065] The structural parameters of the CNC machine tool body are used to characterize the parameters of all the structural parts and joints that make up the CNC machine tool body, and the property parameters of the CNC machine tool body are used to characterize the material property parameters of each structural part and assembly. The material property parameters of each structural part can be provided by the supplier or obtained through experiments, including elastic modulus, Poisson's ratio, density parameters, etc. The joints include but are not limited to machine tool screw joints, linear motor joints, guide rail slider joints, bearing joints, screw nut joints, anchor joints, etc. The property parameters such as stiffness and damping of the joints can be obtained through actual experiments or machine tool database files. The damping parameters of the dynamic model are determined by the damping of the structural parts themselves and the damping of the joints. Preferably, the equivalent method of the joint includes but is not limited to one or more of the node coupling method, spring method, spring-damper method, and virtual material method to ensure that the analysis model is consistent with the mechanical properties of the actual assembled machine tool.

[0066] The structural parameters and property parameters of the tool and workpiece are provided by the supplier or determined by actual experiments or manual settings. Specifically, the weight and size of the workpiece are determined according to the design requirements and the actual workpiece to be processed.

[0067] Step S120 , constructing a finite element analysis model of the entire CNC machine tool according to the structural parameters and property parameters corresponding to the CNC machine tool body, the tool, and the workpiece.

[0068] like Figure 2 As shown, the joints used to form the main body of the CNC machine tool include fixed joints and movable joints. According to the actual mechanical structure of the CNC machine tool, the structural parts and the fixed joints / movable joints formed between the structural parts are combined to obtain the CNC machine tool main body. The tool and the workpiece are combined with the CNC machine tool main body to obtain the substructure model of the CNC machine tool. The substructure module is then combined with the anchor joint to obtain the finite element analysis model of the entire machine.

[0069] Step S130 , configuring the posture and constraint conditions of the whole machine finite element analysis model to obtain a dynamic model of the CNC machine tool.

[0070] Optionally, the posture of the finite element analysis model of the whole machine is determined according to the position of the machining process (i.e., the position of the workpiece), and the constraint conditions of the finite element analysis model of the whole machine are determined by the foot joint of the CNC machine tool body, and the support mode of the foot joint includes two states: free support or fixed support.

[0071] It is understandable that the present invention applies finite element technology to the analysis of the dynamic characteristics of machine tool structures. The dynamic model fully considers the material properties and joint parameters of the CNC machine tool, which can ensure that the dynamic model has sufficiently high accuracy.

[0072] As an optional embodiment, the step of performing transient dynamics characteristic analysis on the dynamic model comprises steps S210-S220.

[0073] In step S210, the load type, load application position, damping parameter, time length and step length of the transient dynamics characteristic analysis are determined.

[0074] The load type of the transient dynamics characteristic analysis includes but is not limited to step load, sinusoidal load, square wave load, pulse load, etc., and the load size can be determined by actual experiment or the weight, acceleration, jerk, etc. of the moving part (single-axis or multi-axis linkage motion shaft).

[0075] The load application position of the transient dynamics characteristic analysis includes but is not limited to the screw nut joint, the primary and secondary coupling node of the linear motor.

[0076] The damping parameter of the transient dynamics characteristic analysis includes the viscous damping, damping ratio and energy dissipation rate of the structural member and joint, which can be obtained by experiment or joint database, etc.

[0077] The time length of the transient dynamics characteristic analysis is determined by experiment and related analysis standards.

[0078] The transient dynamics analysis is completed based on the modal superposition method, which is to solve the mode shape of each frequency to the system response of the load and then combine them according to a certain algorithm. The step length of the transient dynamics characteristic analysis should be less than 1 / 4 of the reciprocal of the maximum modal natural frequency.

[0079] In step S220, the single-axis or multi-axis linkage start-stop impact characteristic analysis is performed on the dynamic model according to the load type, load application position, damping parameter, time length and step length.

[0080] The single-axis or multi-axis linkage start-stop impact characteristic analysis on the dynamic model according to the load type, load application position, damping parameter, time length and step length means that the load type, load application position, damping parameter, time length and step length are input as boundary conditions of the transient dynamics analysis to realize the single-axis or multi-axis linkage start-stop impact characteristic analysis on the dynamic model.

[0081] It can be understood that, on the basis of fully considering the actual structure, material parameter and joint of the machine tool, the dynamic model reflecting the dynamic characteristics of the machine tool is obtained, and the start-stop impact characteristic analysis is performed on the basis, so that the dynamic error of the machine tool under the start-stop working condition is conveniently and quickly identified.

[0082] As an optional embodiment, the start-stop impact characteristic curve comprises an oscillation decay characteristic curve, and correspondingly, the step of judging whether the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index according to the respective oscillation decay characteristic curves of the tool tip and the workpiece comprises steps S310-S320.

[0083] In step S310, the dynamic error curve of the tool tip relative to the workpiece is obtained according to the amplitudes of the respective oscillation decay characteristic curves of the tool tip and the workpiece at the same time node.

[0084] In step S320, whether the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index is judged according to the maximum amplitude of the dynamic error curve.

[0085] Figure 3 a is a schematic diagram of an oscillation decay characteristic curve of a tool tip under a start-stop working condition of a machine tool provided by the application, Figure 3 b is a schematic diagram of an oscillation decay characteristic curve of a workpiece under a start-stop working condition of a machine tool provided by the application, as shown in Figure 3 a and Figure 3 b, the respective oscillation decay characteristic curves of the tool tip and the workpiece are oscillation decay characteristic curves in a given time, and the type of the three-way oscillation decay characteristic curve can be speed, acceleration, displacement, etc. under different excitations.

[0086] Figure 4 The dynamic error curve of the tool tip relative to the workpiece is obtained according to the difference between the amplitudes of the respective oscillation decay characteristic curves of the tool tip and the workpiece at the same time node. The maximum amplitude in the transient characteristic curve directly affects the geometric accuracy of the machine tool in processing the workpiece, and may cause the machining accuracy of the numerical control machine tool to be unqualified. Therefore, the maximum amplitude of the dynamic error curve of the tool tip relative to the workpiece is determined, and whether the maximum amplitude meets the preset dynamic error index is judged. The embodiment of the application takes the type of the three-way oscillation decay characteristic curve as displacement as an example for description, and the preset dynamic error index can be that the three-way dynamic error of the tool tip relative to the workpiece under the maximum start-stop acceleration is controlled within 5 2 , that is, whether the maximum amplitude of the dynamic error curve is controlled within 5 um . um

[0087] It can be understood that the dynamic error curve of the tool tip relative to the workpiece is obtained through the respective oscillation decay characteristic curves of the tool tip and the workpiece, the problem that the machining accuracy cannot be guaranteed when the natural frequency and the dynamic stiffness are taken as the optimization target in the previous dynamic characteristic analysis is solved, the dynamic characteristics of the numerical control machine tool can be more accurately evaluated, and the high-speed and high-precision machining of the numerical control machine tool is ensured.

[0088] ​As an optional embodiment, the step of performing modal analysis on the numerical control machine tool body according to the frequency domain characteristic curve of the start-stop impact characteristic curve to determine the weak link of the numerical control machine tool body comprises steps S330-S350.

[0089] In step S330, the natural frequency corresponding to at least one frequency domain peak value of the frequency domain characteristic curve of the start-stop impact characteristic curve is determined.

[0090] The Fourier transform is performed on the vibration attenuation characteristic curve corresponding to each of the tool tip and the workpiece, respectively, to obtain the vibration attenuation characteristic Fourier transform curve corresponding to each of the tool tip and the workpiece, i.e. the frequency domain characteristic curve of the start-stop impact characteristic curve. According to the Fourier transform curve, the three-direction frequency domain amplitude with a larger value and the corresponding natural frequency corresponding to each of the tool tip and the workpiece can be obtained.

[0091] The target number of the amplitude with a larger value in the frequency domain is selected according to the dynamic error evaluation of the machine tool. The start-stop impact characteristic of the machine tool is determined by the comprehensive action of multiple modes. If the dynamic error is out of tolerance, the main modal frequency causing the dynamic error out of tolerance cannot be determined only in the time domain. By the three-direction FFT change, the main modal frequency causing the dynamic error out of tolerance can be found, and the corresponding modal shape is found. The main reason causing the modal to appear is found through the strain energy, so that the target-oriented optimization is performed. Figure 5 a and Figure 5 b, the natural frequency corresponding to the larger frequency domain amplitude of the tool tip in the Y-axis direction is 70 Hz, and the natural frequency corresponding to the larger frequency domain amplitude of the workpiece in the Y-axis direction is 4 Hz and 49 Hz.

[0092] In step S340, the modal analysis is performed on the numerical control machine tool body to determine the vibration mode of the structural part of the numerical control machine tool body at each natural frequency.

[0093] The modal analysis includes but is not limited to the prestressed modal analysis under the working conditions of the temperature field, the self-weight and the lead screw stretching of the numerical control machine tool body. The modal analysis is performed on the numerical control machine tool body to obtain the vibration mode and the natural frequency of each order of the machine tool in the frequency range of interest, wherein the modal order is ensured to be greater than 90% of the three-direction effective mass parameter coefficient of the machine tool. The vibration mode corresponding to the natural frequency is selected from the modal analysis result, so as to ensure that the finite element analysis model has high enough precision. If the extracted modal order is not enough, the analysis requirement cannot be met.

[0094] Table 1: Table of natural frequencies of the first 9 orders obtained by modal analysis of the machine tool

[0095]

[0096] The peak frequency of the tool tip and the workpiece corresponds to the 3rd order and the 5th order of the machine tool.

[0097] Step S350, according to the mode shape of the structural member of the numerical control machine tool body at each natural frequency, determining the weak link of the numerical control machine tool body.

[0098] Optionally, the determining the weak link of the numerical control machine tool body according to the mode shape of the structural member of the numerical control machine tool body at each natural frequency comprises steps S351-S352.

[0099] Step S351, according to the mode shape of the structural member of the numerical control machine tool body at each natural frequency, determining the strain energy of the structural member of the numerical control machine tool body at each natural frequency to construct a strain energy cloud map.

[0100] The mode shape of the structural member of the numerical control machine tool body at each natural frequency is post-processed to obtain the strain energy of the structural member of the numerical control machine tool body at each natural frequency, and all strain energies are combined to obtain a strain energy cloud map.

[0101] Step S352, according to the strain energy cloud map, the structural member with a strain energy reaching a preset value is taken as the weak link of the numerical control machine tool body.

[0102] Optionally, the structural member with the maximum strain energy can be taken as the weak link of the numerical control machine tool body.

[0103] It can be understood that the present application intuitively obtains the corresponding natural frequency and modal shape affecting the tool tip and the workpiece to generate a larger dynamic error in the machine tool design stage or actual use process, and the weak link is identified on this basis, so as to perform a target-oriented dynamic optimization design.

[0104] As shown in Figure 6 , as an optional embodiment, the optimization design scheme corresponding to the weak link includes but is not limited to topology optimization, size optimization, joint parameter optimization, damping parameter optimization, etc.

[0105] It can be understood that the present application modifies the numerical control machine tool structure in combination with the joint parameter optimization, the damping parameter optimization, etc. for the weak link, which fully utilizes the advantages of numerical simulation analysis, such as easy modification of the geometric model and equivalent of the joint dynamic characteristic parameters.

[0106] The preferred embodiments of the present application will be described below with reference to the accompanying drawings.

[0107] As shown in Figure 7 , the present application provides a numerical control machine tool optimization design method based on start-stop impact characteristics, comprising steps A-J.

[0108] A. Define the dynamic error index under the design requirement acceleration.

[0109] B. Establishing a finite element analysis model of the machine tool, and obtaining a dynamic model.

[0110] C. Carrying out transient dynamic characteristic analysis on the dynamic model.

[0111] D. According to the transient dynamic characteristic analysis result, determining a three-way start-stop impact characteristic curve of the tool tip and the workpiece under a preset working condition.

[0112] E. According to the start-stop impact characteristic curve, judging the start-stop impact characteristic of the machine tool, and determining whether the start-stop impact characteristic of the machine tool meets a dynamic error index.

[0113] F. The start-stop impact characteristic curve includes an oscillation decay curve, and the Fourier transform curve is obtained by carrying out Fourier transform on the oscillation decay curve of the tool tip and the workpiece under the condition that the dynamic error index is not met.

[0114] G. According to the Fourier transform curve, determining an inherent frequency corresponding to a larger peak value in a frequency domain.

[0115] H. In combination with modal analysis, obtaining information such as a modal vibration mode corresponding to different peak inherent frequencies of the numerical control machine tool.

[0116] I. Identifying and optimizing and improving a weak link of the numerical control machine tool.

[0117] J. Comparing and verifying the optimized result until a machine tool structure meeting a design requirement is obtained.

[0118] As shown in the figure, the steps B-I of the present application are repeated until a machine tool structure meeting a design requirement is obtained, and the optimization of the weak link includes optimization of a structural member and optimization of a joint part. Figure 8 According to the a-c, it can be known that the dynamic error of the machine tool structure in X, Y and Z three directions is improved by the optimization of the present application. Figure 9 Figure 9

[0119] ​​The application can analyze and compare the dynamic performance of the optimized machine tool, can quickly predict the improvement effect, greatly saves the development cycle of the machine tool, shortens the time for troubleshooting and other problems in actual use, ensures that the evaluation result is closer to the actual production, and thus ensures the geometric precision of the machine tool processing. The application plays a good guiding role in identifying and optimizing the weak links of the dynamic error evaluation and the machine tool, reduces the iteration times of the machine tool version, and improves the competitiveness of the machine tool on the market. In addition, the application also considers the material physical parameters and the parameters such as the joint surface of the structural part, establishes a dynamic analysis model which can reflect the actual machining precision of the machine tool, is simple and convenient, and has better universality; and can identify the weak links of the structure corresponding to the dynamic precision of the machine tool, the analysis result is accurate and reliable, and has strong persuasiveness, and plays a good guiding role in the optimization design of the machine tool; the weak links and process parameters of the structural part are modified by using the convenient and fast finite element modeling technology, the dynamic characteristics and other parameters of the optimized machine tool are directly obtained, the universality and comparability of the dynamic error evaluation result of the machine tool are enhanced, technical support is provided for the structural optimization and design of the machine tool, and the development cycle of the machine tool is greatly shortened.

[0120] The numerical control machine tool optimization design device provided by the application is described below, and the numerical control machine tool optimization design device described below can be correspondingly referred to the numerical control machine tool optimization design method described above.

[0121] Figure 10 The structure diagram of the numerical control machine tool optimization design device provided by the application is shown in Figure 10 The application also provides a numerical control machine tool optimization design device, which comprises the following modules.

[0122] The construction module 1010 is configured to construct a dynamic model of the numerical control machine tool, wherein the dynamic model comprises a numerical control machine tool body, a tool arranged on the numerical control machine tool body, and a workpiece.

[0123] The analysis module 1020 is configured to perform transient dynamic characteristic analysis on the dynamic model to obtain a tool tip of the tool and a start-stop impact characteristic curve of the workpiece.

[0124] The judgment module 1030 is configured to determine whether a dynamic error curve of the tool tip relative to the workpiece satisfies a preset dynamic error index according to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively, and if not, perform modal analysis on the numerical control machine tool body according to a frequency domain characteristic curve of the start-stop impact characteristic curve to determine a weak link of the numerical control machine tool body.

[0125] The optimization module 1040 is configured to return the step of constructing the dynamic model of the numerical control machine tool according to the optimization design scheme corresponding to the weak link until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

[0126] As an embodiment, the start-stop impact characteristic curve comprises an oscillation decay characteristic curve, and the judging module 1030 is further configured to:

[0127] obtain the dynamic error curve of the tool tip relative to the workpiece according to the amplitudes of the oscillation decay characteristic curves of the tool tip and the workpiece at the same time node;

[0128] determine whether the dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index according to the maximum amplitude of the dynamic error curve.

[0129] As an embodiment, the judging module 1030 is further configured to:

[0130] determine the natural frequencies corresponding to at least one frequency domain peak of the frequency domain characteristic curve of the start-stop impact characteristic curve;

[0131] perform modal analysis on the numerical control machine tool body to determine the vibration modes of the structural members of the numerical control machine tool body at the natural frequencies;

[0132] determine the weak link of the numerical control machine tool body according to the vibration modes of the structural members of the numerical control machine tool body at the natural frequencies.

[0133] As an embodiment, the judging module 1030 is further configured to:

[0134] determine the strain energy of the structural members of the numerical control machine tool body at the natural frequencies according to the vibration modes of the structural members of the numerical control machine tool body at the natural frequencies to construct a strain energy cloud map;

[0135] determine the structural member with a strain energy reaching a preset value as the weak link of the numerical control machine tool body according to the strain energy cloud map.

[0136] As an embodiment, the constructing module 1010 is further configured to:

[0137] determine the structural parameters and attribute parameters corresponding to the numerical control machine tool body, the tool and the workpiece respectively;

[0138] construct a whole machine finite element analysis model of the numerical control machine tool according to the structural parameters and attribute parameters corresponding to the numerical control machine tool body, the tool and the workpiece respectively;

[0139] The posture and constraint condition of the whole machine finite element analysis model are configured to obtain a dynamic model of the numerical control machine tool.

[0140] As an embodiment, the analysis module 1020 is further configured to:

[0141] determine a load type, a load application position, a damping parameter, a time length and a step length for transient dynamic characteristic analysis;

[0142] perform uniaxial or multi-axis linkage start-stop impact characteristic analysis on the dynamic model according to the load type, the load application position, the damping parameter, the time length and the step length.

[0143] It should be noted that the numerical control machine tool optimization design device provided by the present application can perform the numerical control machine tool optimization design method described in any of the above embodiments during actual operation, and has the technical effects corresponding to the method, which will not be described here.

[0144] Figure 11 An example of a schematic diagram of a physical structure of an electronic device is shown in Figure 11 The electronic device can include a processor 1110, a communications interface 1120, a memory 1130 and a communications bus 1140, wherein the processor 1110, the communications interface 1120 and the memory 1130 communicate with each other through the communications bus 1140. The processor 1110 can invoke a logical instruction in the memory 1130 to execute a numerical control machine tool optimization design method, which includes: constructing a dynamic model of a numerical control machine tool, the dynamic model including a numerical control machine tool body, a tool disposed on the numerical control machine tool body and a workpiece; performing transient dynamic characteristic analysis on the dynamic model to obtain start-stop impact characteristic curves of a tool tip of the tool and the workpiece; determining whether a dynamic error curve of the tool tip relative to the workpiece satisfies a preset dynamic error index according to the respective start-stop impact characteristic curves of the tool tip and the workpiece, and if not, performing modal analysis on the numerical control machine tool body according to frequency domain characteristic curves of the start-stop impact characteristic curves to determine a weak link of the numerical control machine tool body; returning to the step of constructing the dynamic model of the numerical control machine tool according to an optimization design scheme corresponding to the weak link until the dynamic error curve of the tool tip relative to the workpiece satisfies the dynamic error index.

[0145] In addition, the logic instructions in the memory 1130 described above can be implemented in the form of a software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or the part that contributes to the prior art or part of the technical solutions can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0146] In another aspect, the present application also provides a computer program product, which comprises a computer program, the computer program can be stored on a non-transitory computer readable storage medium, and the computer program can be executed by a processor, so that the computer can execute the numerical control machine tool optimization design method provided by the above-mentioned method, which comprises the following steps: constructing a dynamic model of a numerical control machine tool, the dynamic model comprising a numerical control machine tool body, a tool arranged on the numerical control machine tool body, and a workpiece; performing transient dynamic characteristic analysis on the dynamic model to obtain a start-stop impact characteristic curve of a tool tip of the tool and the workpiece; judging whether a dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index according to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively, if not, performing modal analysis on the numerical control machine tool body according to a frequency domain characteristic curve of the start-stop impact characteristic curve to determine a weak link of the numerical control machine tool body; returning to the step of constructing the dynamic model of the numerical control machine tool according to an optimization design scheme corresponding to the weak link until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

[0147] In yet another aspect, the present application also provides a non-transitory computer readable storage medium having stored thereon a computer program, which, when executed by a processor, implements the numerical control machine tool optimization design method provided by the above method, and the method comprises: constructing a dynamic model of a numerical control machine tool, the dynamic model comprising a numerical control machine tool body, a tool arranged on the numerical control machine tool body, and a workpiece; performing transient dynamic characteristic analysis on the dynamic model to obtain a start-stop impact characteristic curve of a tool tip of the tool and the workpiece; determining whether a dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index according to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively, and if not, performing modal analysis on the numerical control machine tool body according to a frequency domain characteristic curve of the start-stop impact characteristic curve to determine a weak link of the numerical control machine tool body; and returning to the step of constructing the dynamic model of the numerical control machine tool according to an optimization design scheme corresponding to the weak link until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

[0148] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, i.e., can be located in one place, or can be distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiment according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0149] From the above description of the embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software and necessary universal hardware platforms, and of course can also be realized by hardware. Based on such understanding, the above technical solutions can be embodied in the form of a software product, which can be stored in a computer readable storage medium, such as a ROM / RAM, a magnetic disk, an optical disk, etc., and includes a plurality of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0150] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements to some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for optimizing the design of a CNC machine tool, characterized in that: include: Constructing a dynamic model of a CNC machine tool, the dynamic model including a CNC machine tool body, a tool provided on the CNC machine tool body, and a workpiece; Performing transient dynamic characteristic analysis on the dynamic model to obtain a start-stop impact characteristic curve of the tool tip and the workpiece; Based on the start-stop impact characteristic curves corresponding to the tool tip and the workpiece, it is determined whether a dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index. If not, a modal analysis is performed on the CNC machine tool body based on a frequency domain characteristic curve of the start-stop impact characteristic curve to determine the weak links of the CNC machine tool body. The dynamic error curve of the tool tip relative to the workpiece is determined based on the start-stop impact characteristic curves corresponding to the tool tip and the workpiece. The dynamic error of the tool tip relative to the workpiece is used as an evaluation standard for the machining accuracy of the CNC machine tool to determine the dynamic error during the machining stage and the feed axis causing the dynamic error. According to the optimization design solution corresponding to the weak link, return to the step of constructing the dynamic model of the CNC machine tool until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

2. The CNC machine tool optimization design method according to claim 1, characterized in that: The start-stop impact characteristic curve includes an oscillation attenuation characteristic curve. Correspondingly, judging whether a dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index based on the start-stop impact characteristic curves corresponding to the tool tip and the workpiece, includes: Obtaining a dynamic error curve of the tool tip relative to the workpiece based on the amplitudes of the oscillation attenuation characteristic curves corresponding to the tool tip and the workpiece at the same time node; According to the maximum amplitude of the dynamic error curve, it is determined whether the dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index.

3. The CNC machine tool optimization design method according to claim 2, characterized in that: The performing modal analysis on the CNC machine tool body according to the frequency domain characteristic curve of the start-stop impact characteristic curve to determine the weak links of the CNC machine tool body includes: Determining a natural frequency corresponding to at least one frequency domain peak of a frequency domain characteristic curve of the start-stop impact characteristic curve; Performing modal analysis on the CNC machine tool body to determine vibration modes of structural components of the CNC machine tool body at each of the natural frequencies; The weak links of the CNC machine tool body are determined according to the vibration modes of the structural components of the CNC machine tool body at the natural frequencies.

4. The CNC machine tool optimization design method according to claim 3, characterized in that: Determining the weak links of the CNC machine tool body according to the vibration modes of the structural components of the CNC machine tool body at the natural frequencies includes: determining the strain energy of the structural components of the CNC machine tool body at each of the natural frequencies according to the vibration modes of the structural components of the CNC machine tool body at each of the natural frequencies to construct a strain energy cloud map; According to the strain energy cloud diagram, the structural parts whose strain energy reaches a preset value are regarded as the weak links of the CNC machine tool body.

5. The CNC machine tool optimization design method according to claim 1, characterized in that: The construction of the dynamic model of the CNC machine tool includes: Determining structural parameters and property parameters corresponding to the CNC machine tool body, the tool, and the workpiece; Constructing a finite element analysis model of the entire CNC machine tool according to the structural parameters and property parameters corresponding to the CNC machine tool body, the tool, and the workpiece; The posture and constraint conditions of the whole machine finite element analysis model are configured to obtain the dynamic model of the CNC machine tool.

6. The CNC machine tool optimization design method according to claim 5, characterized in that: The posture of the whole machine finite element analysis model is determined according to the position of the workpiece, and the constraint conditions of the whole machine finite element analysis model are determined by the foot joint of the CNC machine tool body.

7. The CNC machine tool optimization design method according to claim 1, characterized in that: The performing transient dynamic characteristics analysis on the dynamic model includes: Determine the load type, load application location, damping parameters, duration, and step size for transient dynamic characteristics analysis; According to the load type, load application position, damping parameters, duration and step length, the dynamic model is subjected to single-axis or multi-axis linkage start-stop impact characteristic analysis.

8. A CNC machine tool optimization design device, characterized in that: include: A construction module, configured to construct a dynamic model of a CNC machine tool, wherein the dynamic model includes a CNC machine tool body, a tool provided on the CNC machine tool body, and a workpiece; an analysis module, configured to perform transient dynamic characteristic analysis on the dynamic model to obtain a start-stop impact characteristic curve of the tool tip and the workpiece; a judgment module for judging whether a dynamic error curve of the tool tip relative to the workpiece satisfies a preset dynamic error index based on the start-stop impact characteristic curves corresponding to the tool tip and the workpiece, and if not, performing a modal analysis on the CNC machine tool body based on a frequency domain characteristic curve of the start-stop impact characteristic curve to determine a weak link of the CNC machine tool body; the dynamic error curve of the tool tip relative to the workpiece is determined based on the start-stop impact characteristic curves corresponding to the tool tip and the workpiece, and the dynamic error of the tool tip relative to the workpiece is used as an evaluation standard for the machining accuracy of the CNC machine tool to determine the dynamic error during the machining stage and the feed axis causing the dynamic error; The optimization module is used to return to the step of constructing the dynamic model of the CNC machine tool according to the optimization design scheme corresponding to the weak link, until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the CNC machine tool optimization design method according to any one of claims 1 to 7 is implemented.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the CNC machine tool optimization design method according to any one of claims 1 to 7 is implemented.

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