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

Abstract

The invention provides a numerical control machine tool optimization design method and device, electronic equipment and a storage medium, and belongs to the technical field of numerical control machine tool optimization design. The method comprises the steps that a dynamic model of a numerical control machine tool is constructed, and the dynamic model comprises a numerical control machine tool body, a tool and a workpiece; performing transient dynamic characteristic analysis on the dynamic model to obtain a start-stop impact characteristic curve of a tool nose of the tool and a workpiece; according to the start-stop impact characteristic curve, whether the dynamic error curve of the tool nose relative to the workpiece meets a preset dynamic error index or not is judged, if not, modal analysis is conducted on the numerical control machine tool body according to a frequency domain characteristic curve of the start-stop impact characteristic curve, and weak links of the numerical control machine tool body are determined and optimized till the dynamic error index is met. The dynamic error curve of the tool nose relative to the workpiece is adopted to represent the dynamic error of the numerical control machine tool, the dynamic characteristics of the numerical control machine tool can be evaluated more accurately, and high-precision machining of the numerical control machine tool is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of CNC machine tool optimization design, and in particular to a CNC machine tool optimization design method, device, electronic equipment and storage medium. Background Art

[0002] As the manufacturing industry continues to increase its requirements for precision and ultra-precision machining of CNC machine tools, the impact of dynamic error factors on the spatial positioning accuracy of CNC machine tools is becoming more and more obvious. The machining accuracy of CNC machine tools determines the product quality of the workpiece being machined. Among them, improving the dynamic characteristics of CNC machine tools is an important aspect of improving the machining accuracy of CNC machine tools. In order to achieve high-precision machining of CNC machine tools, it is necessary to ensure that the CNC machine tools have sufficiently small dynamic errors. At present, in the research on the dynamic optimization design of CNC machine tools, the goal of dynamic characteristic analysis is still to obtain modalities and stiffness. The modalities are used to reflect the dynamic response characteristics of the CNC machine tool structure, and the stiffness is used to reflect the anti-deformation characteristics of the CNC machine tool structure. It cannot optimize the dynamic errors generated by CNC machine tools during the machining stage, resulting in the machining accuracy still needs to be improved. Summary of the invention

[0003] The present invention provides a method, device, electronic device and storage medium for optimizing the design of CNC machine tools, which can solve the defect that the goal of the existing dynamic characteristic analysis of CNC machine tools is mainly to obtain the mode and stiffness, but cannot optimize the dynamic errors generated by the CNC machine tools during the processing stage, resulting in the processing accuracy still needs to be improved.

[0004] The present invention provides a method for optimizing the design of a numerically controlled machine tool, comprising: Constructing a dynamic model of a numerically controlled machine tool, wherein the dynamic model includes a numerically controlled machine tool body, a tool disposed on the numerically controlled machine tool body, and a workpiece; Performing transient dynamic characteristic analysis on the dynamic model to obtain start-stop impact characteristic curves of the tool tip and the workpiece; According to the start-stop impact characteristic curves respectively corresponding to the tool tip and the workpiece, it is judged whether the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index; if not, a modal analysis is performed on the CNC machine tool body according to the frequency domain characteristic curve of the start-stop impact characteristic curve to determine the weak link of the CNC machine tool body; According to the optimization design scheme 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.

[0005] As an embodiment, the start-stop impact characteristic curve includes an oscillation decay characteristic curve. Correspondingly, determining whether the 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 includes: Obtaining the dynamic error curve of the tool tip relative to the workpiece according to the amplitudes of the oscillation decay characteristic curves corresponding to the tool tip and the workpiece at the same time node; 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.

[0006] As an embodiment, performing modal analysis on the main body of the CNC machine tool according to the frequency-domain characteristic curve of the start-stop impact characteristic curve to determine the weak links of the main body of the CNC machine tool includes: Determining the natural frequencies corresponding to at least one frequency-domain peak of the frequency-domain characteristic curve of the start-stop impact characteristic curve; Performing modal analysis on the main body of the CNC machine tool to determine the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies; Determining the weak links of the main body of the CNC machine tool according to the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies.

[0007] As an embodiment, determining the weak links of the main body of the CNC machine tool according to the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies includes: Determining the strain energy of the structural components of the main body of the CNC machine tool at each of the natural frequencies according to the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies to construct a strain energy contour map; Regarding the structural components with the strain energy reaching the preset value as the weak links of the main body of the CNC machine tool according to the strain energy contour map.

[0008] As an embodiment, constructing the dynamic model of the CNC machine tool includes: Determining the structural parameters and attribute parameters corresponding to the main body of the CNC machine tool, the tool, and the workpiece respectively; Constructing an overall finite element analysis model of the CNC machine tool according to the structural parameters and attribute parameters corresponding to the main body of the CNC machine tool, the tool, and the workpiece respectively; Configuring the attitude and constraint conditions of the overall finite element analysis model to obtain the dynamic model of the CNC machine tool.

[0009] As an embodiment, the attitude of the overall finite element analysis model is determined according to the position of the workpiece, and the constraint conditions of the overall finite element analysis model are determined by the foundation joint of the main body of the CNC machine tool.

[0010] As an embodiment, the transient dynamic characteristic analysis of the dynamic model includes: Determine the load type, load application position, damping parameter, duration, and step size for the transient dynamic characteristic analysis; According to the load type, load application position, damping parameter, duration, and step size, perform single-axis or multi-axis linkage start-stop shock characteristic analysis on the dynamic model.

[0011] The present invention also provides a numerical control machine tool optimization design device, including: A construction module for constructing a dynamic model of a numerical control machine tool, where the dynamic model includes the main body of the numerical control machine tool, a tool provided on the main body of the numerical control machine tool, and a workpiece; An analysis module for performing transient dynamic characteristic analysis on the dynamic model to obtain the start-stop shock characteristic curves of the tool tip of the tool and the workpiece; A judgment module for judging whether the dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index according to the start-stop shock characteristic curves corresponding to the tool tip and the workpiece respectively. If not, perform modal analysis on the main body of the numerical control machine tool according to the frequency domain characteristic curve of the start-stop shock characteristic curve to determine the weak link of the main body of the numerical control machine tool; An optimization module for returning to 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 of the tool relative to the workpiece meets the dynamic error index.

[0012] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, it implements the numerical control machine tool optimization design method as described in any one of the above.

[0013] The present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the numerical control machine tool optimization design method as described in any one of the above.

[0014] The numerical control machine tool optimization design method, device, electronic device, and storage medium provided by the present invention perform transient dynamic characteristic analysis on the dynamic model to obtain the start-stop shock characteristic curves of the tool tip and the workpiece, and judge whether the dynamic error curve of the tool tip relative to the workpiece in the machining stage meets the preset dynamic error index according to the start-stop shock characteristic curves, which can more accurately evaluate the dynamic characteristics of the numerical control machine tool and ensure high-precision machining of the numerical control machine tool. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the attached drawings required for the description of the embodiments or the prior art. Obviously, the attached drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other attached drawings can also be obtained based on these attached drawings.

[0016] Figure 1 It is one of the schematic flowcharts of the numerical control machine tool optimization design method provided by the present invention.

[0017] Figure 2 It is the schematic flowchart of constructing the overall finite element analysis model of the numerical control machine tool provided by the present invention.

[0018] Figure 3 a is the schematic diagram of the oscillation attenuation characteristic curve of the tool tip under the starting and stopping conditions of the machine tool provided by the present invention, Figure 3 b is the schematic diagram of the oscillation attenuation characteristic curve of the workpiece under the starting and stopping conditions of the machine tool provided by the present invention.

[0019] Figure 4 It is the schematic diagram of the dynamic error curve of the tool tip relative to the workpiece provided by the present invention.

[0020] Figure 5 a is the schematic diagram of the Fourier transform curve of the Y-direction oscillation attenuation characteristic of the tool tip provided by the present invention, Figure 5 b is the schematic diagram of the Fourier transform curve of the Y-direction oscillation attenuation characteristic of the workpiece provided by the present invention.

[0021] Figure 6 It is the schematic diagram of the optimization design scheme provided by the present invention.

[0022] Figure 7 It is the second schematic flowchart of the numerical control machine tool optimization design method provided by the present invention.

[0023] Figure 8 It is the flow chart of identifying the weak structural links and improving and optimizing the iteration provided by the present invention.

[0024] Figure 9 a- Figure 9 c is the comparison chart of the X, Y, and Z three-direction dynamic errors of the machine tool before and after optimization provided by the present invention.

[0025] Figure 10 It is the schematic diagram of the structure of the numerical control machine tool optimization design device provided by the present invention.

[0026] Figure 11 It is the schematic diagram of the structure of the electronic device provided by the present invention. Detailed implementation manners

[0027] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] It should be noted that all actions of obtaining signals, information or data in the present invention are carried out on the premise of complying with the corresponding data protection regulations and policies of the location and with the authorization given by the owner of the corresponding device.

[0029] During the actual machining process of a numerically controlled machine tool, it often occurs that the geometric accuracy of the numerically controlled machine tool is good but the machining accuracy is insufficient. However, designers and process engineers of numerically controlled machine tools cannot quickly and accurately find the root cause of the problem, resulting in repeated version iterations of numerically controlled machine tools, long R & D cycles, high costs and other problems. In the aspect of dynamic analysis and dynamic design optimization of complex mechanical structures, the finite element method has become the mainstream of the dynamic analysis of numerically controlled machine tools. By using simulation technology, the dynamic error of the whole machine can be predicted and evaluated at the initial stage of the design of numerically controlled machine tools, the weak links of numerically controlled machine tools can be found in time and optimized and improved, which can effectively improve the design quality of products, and then ensure the machining quality and shorten the product R & D cycle.

[0030] However, in the current research on the dynamic optimization design of numerically controlled machine tools, the goal of dynamic characteristic analysis is still mainly to obtain the mode and stiffness, and little attention is paid to the problem that the dynamic error caused by the start-stop impact characteristics of numerically controlled machine tools results in insufficient machining accuracy of workpieces, so that the dynamic characteristics of numerically controlled machine tools cannot meet the requirements of high-efficiency and high-precision machining. In addition, the error of a numerically controlled machine tool includes two parts: static error and dynamic error. The static error includes geometric error, thermal error and assembly error, and the dynamic error is determined by parameters such as mechanical dynamics characteristics. The error of the tool tip measured by a machine tool interferometer includes both static error and dynamic error, and the dynamic error caused by the mechanical structure cannot be separated, and it is difficult to accurately find the main cause affecting the machining accuracy. Although the full closed-loop control technology using grating scales on numerically controlled machine tools can ensure that the moving parts are in the accurate position, it cannot guarantee the position distance error between the grating scale reading head and the tool tip and the workpiece, resulting in defects such as dents, ridges and out-of-tolerance characteristic dimensions on the surface of the machined workpiece. The present invention can effectively solve the change in the distance between the tool tip and the workpiece caused by the positive and negative impact forces generated by the moving parts during the start-stop impact process, well make up for this defect of the full closed-loop control technology, and improve the machining accuracy of workpieces. It can quantitatively analyze the dynamic error caused by the start-stop impact of the machine tool at the design stage and carry out targeted structural optimization, so as to ensure the machining accuracy of the machined workpiece and meet the final cutting effect without multiple version iterations in the later stage of the prototype.

[0031] Figure 1 is one of the flow schematic diagrams of the numerical control machine tool optimization design method provided by the present invention. As Figure 1 shown, the present invention provides an optimization design method for a numerical control machine tool based on the start-stop impact characteristics, which is applicable to the optimization and improvement during the design stage or actual use process of the numerical control machine tool. The method includes steps S100 - S400.

[0032] Step S100, construct a dynamic model of the numerical control machine tool, where the dynamic model includes the main body of the numerical control machine tool, a tool provided on the main body of the numerical control machine tool, and a workpiece.

[0033] Preferably, the dynamic model is a finite element analysis model, which is constructed based on the finite element analysis model, used to simulate the numerical control machine tool, and simulate the actual behavior through numerical calculation. Preferably, the present invention can use the dynamic model to conduct simulation tests, calculate the dynamic error of the whole machine of the machine tool, quantitatively evaluate the dynamic accuracy of the whole machine, determine the structural components that cause larger dynamic errors, and on this basis, guide the machine tool designer to conduct targeted optimization and improvement on the relevant components, which can greatly improve the dynamic error of the whole machine of the machine tool, improve the machining accuracy and surface roughness of the machined workpiece, replace a large number of actual cutting tests after the traditional prototype assembly is completed, thereby reducing the R & D cost and various resource wastes, reducing blind version iterations, and improving the market competitiveness of the machine tool.

[0034] Step S200, conduct transient dynamic characteristic analysis on the dynamic model to obtain the start-stop impact characteristic curves of the tool tip of the tool and the workpiece.

[0035] Transient dynamic characteristic analysis is used to study the dynamic response process of a structure or system under the action of loads that change rapidly with time (such as impact, explosion, vibration, sudden start and stop, etc.). The core goal is to predict the variation laws of parameters such as displacement, stress, strain, and acceleration of the structure with time. In the present invention, conducting transient dynamic characteristic analysis on the dynamic model specifically means analyzing the start-stop impact characteristics of the dynamic model to obtain the three-dimensional start-stop impact characteristic curves of the tool tip and the workpiece under preset working conditions. The three dimensions refer 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.

[0036] Step S300, according to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively, judge whether the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index. If not, conduct modal analysis on the main body of the numerical control machine tool according to the frequency domain characteristic curves of the start-stop impact characteristic curves to determine the weak links of the main body of the numerical control machine tool.

[0037] 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 a machine tool is closely related to the dynamic error generated by the start-stop impact characteristics of the machine tool. However, in the existing research on the dynamic optimization design of machine tools, the goal of dynamic characteristic analysis is still mainly to obtain the modal and stiffness. The present invention provides a new technical index for the dynamic error evaluation of CNC machine tools, that is, the dynamic error of the tool tip relative to the workpiece, which solves the problem that in the previous dynamic characteristic analysis, the natural frequency and dynamic stiffness were used as the optimization objectives, ignoring the dynamic error generated by the start-stop impact characteristics and unable to guarantee the machining accuracy. In addition, the dynamic error of the tool tip relative to the workpiece is related to the mechanical structure of the CNC machine tool, which is beneficial to determining the main structural components affecting the machining accuracy.

[0038] Optionally, the main body of the CNC machine tool includes a single-axis or multi-axis linkage motion axis. The single-axis or multi-axis linkage motion axis is used to drive the moving part to translate or rotate according to the NC instruction, and then drive the tool and the workpiece to move and / or rotate relatively in the XYZ coordinate system and other coordinate systems along the set direction and at the set speed / acceleration, so as to obtain the workpiece that meets the requirements. Correspondingly, the dynamic error index includes the dynamic error index under the acceleration condition of the design requirement. The acceleration conditions include the rapid feed condition G00 and the cutting feed condition G01. The cutting feed condition G01 includes, but is not limited to, information such as different feed speeds, spindle speeds, and cutting depths. The manifestation forms of the dynamic error index include, but are not limited to, undercutting, overcutting, surface vibration marks, and reduced positioning accuracy of the surface feature dimensions of the workpiece.

[0039] Modal analysis is the core technology for studying the dynamic characteristics of structures, which is used to determine the natural frequency, vibration mode (modal shape), and damping ratio of the structure, help understand the vibration behavior of the structure under dynamic loads, and provide key basis for frequency avoidance, vibration reduction, and optimization by identifying the "vibration fingerprints" (frequency and vibration mode) of the structure. Modal analysis can be realized based on finite element analysis software. Perform modal analysis on the main body of the CNC machine tool according to the start-stop impact characteristic curve to determine the weak links of the main body of the CNC machine tool. Specifically, it means to determine the natural frequency at the location with a large dynamic error according to the start-stop impact characteristic curve, and combine modal analysis to obtain the modal vibration mode corresponding to the natural frequency to determine the weak links.

[0040] Step S400, according to the optimization design scheme 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 of the tool relative to the workpiece meets the dynamic error index.

[0041] According to the optimized design scheme, reconstruct the dynamic model, and verify the reconstructed dynamic model to determine whether it meets the design requirements. If it meets the design requirements, the optimization is completed; otherwise, repeat steps S100 - S400 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 further, and the process ends.

[0042] It can be understood that the present invention uses the dynamic error of the tool tip relative to the workpiece as the evaluation standard for the machining accuracy of the CNC machine tool, provides an intuitive technical index to characterize the dynamic error of the machine tool, can determine the dynamic error in the machining stage, and further determine the feed axis with a larger dynamic error, so as to guide the designer to carry out targeted optimization and improvement on relevant components, which is beneficial to more accurately evaluate the dynamic characteristics of the CNC machine tool, and solves the problem that in the past, the natural frequency and dynamic stiffness were used as the optimization objectives in the dynamic characteristic analysis, ignoring the start-stop impact characteristics and unable to guarantee the machining accuracy.

[0043] As an optional embodiment, the construction of the dynamic model of the CNC machine tool includes steps S110 - S130.

[0044] Step S110, determine the respective structural parameters and attribute parameters of the CNC machine tool body, the tool, and the workpiece.

[0045] The structural parameters of the CNC machine tool body are used to characterize the parameters of all structural components and joints that make up the CNC machine tool body, and the attribute parameters of the CNC machine tool body are used to characterize the material attribute parameters of each structural component and combination part. The material attribute parameters of each structural component 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, lead screw nut joints, foundation joints, etc. The attribute parameters such as stiffness and damping of the joints can be obtained through actual experiments or machine tool database files, etc. The self-damping of the structural components and the damping of the joints determine the damping parameters of the dynamic model. Preferably, the equivalent methods of the joints include but are not limited to one or several of the node coupling method, spring method, spring-damping method, virtual material method, etc., to ensure that the analysis model is consistent with the mechanical characteristics of the actually assembled machine tool.

[0046] The structural parameters and attribute parameters of the tool and the workpiece are determined by the supplier, actual experiments, or manual setting. Specifically, the weight and size of the workpiece are determined according to the design requirements and the actual workpiece to be machined.

[0047] Step S120, construct a whole-machine finite element analysis model of the CNC machine tool according to the respective structural parameters and attribute parameters of the CNC machine tool body, the tool, and the workpiece.

[0048] As shown Figure 2 in the figure, the joints for forming the main body of the CNC machine tool include fixed joints and movable joints. According to the mechanical structure of the actual CNC machine tool, the fixed joints / movable joints formed between the structural parts and each structural part are combined to obtain the main body of the CNC machine tool. The tool and the workpiece are combined onto the main body of the CNC machine tool to obtain the sub-structure model of the CNC machine tool. Then, the sub-structure module is combined with the floor joint to obtain the finite element analysis model of the whole machine.

[0049] Step S130, configure the attitude and constraint conditions of the finite element analysis model of the whole machine to obtain the dynamic model of the CNC machine tool.

[0050] Optionally, the attitude of the finite element analysis model of the whole machine is determined according to the position during 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 floor joint of the main body of the CNC machine tool. The support modes of the floor joint include two states: free support or fixed support.

[0051] It can be understood that the present invention applies the finite element technology to the analysis of the dynamic characteristics of the machine tool structure. The dynamic model fully considers parameters such as the material properties and joints of the CNC machine tool, which can ensure that the dynamic model has a sufficiently high accuracy.

[0052] As an optional embodiment, the transient dynamic characteristic analysis of the dynamic model includes steps S210 - S220.

[0053] Step S210, determine the load type, load application position, damping parameters, duration, and step size of the transient dynamic characteristic analysis.

[0054] The load types of the transient dynamic characteristic analysis include but are not limited to step load, sine load, square wave load, pulse load, etc. The magnitude of the load can be obtained from actual experiments or determined by parameters such as the weight, acceleration, and jerk of the moving parts (single-axis or multi-axis linkage moving axes).

[0055] The load application positions of the transient dynamic characteristic analysis include but are not limited to the screw-nut joint and the primary-secondary coupling node of the linear motor.

[0056] The damping parameters of the transient dynamic characteristic analysis include the viscous damping, damping ratio, and energy dissipation rate of the structural parts and joints, which can be obtained through experiments or the joint database, etc.

[0057] The duration of the transient dynamic characteristic analysis is determined by experiments and relevant analysis standards.

[0058] The transient dynamic analysis is completed based on the mode superposition method. The mode superposition method is to solve the system responses of the vibration modes at each frequency to the load respectively and then combine them together according to a certain algorithm. The step size of the transient dynamic characteristic analysis should be less than 1 / 4 of the reciprocal of the maximum modal natural frequency it intercepts.

[0059] Step S220: According to the load type, load application position, damping parameter, duration and step size, perform single-axis or multi-axis linkage start-stop shock characteristic analysis on the dynamic model.

[0060] Performing single-axis or multi-axis linkage start-stop shock characteristic analysis on the dynamic model according to the load type, load application position, damping parameter, duration and step size specifically means inputting the load type, load application position, damping parameter, duration and step size as the boundary conditions of the transient dynamic analysis to realize single-axis or multi-axis linkage start-stop shock characteristic analysis on the dynamic model.

[0061] It can be understood that based on fully considering the actual structure, material parameters and joints of the machine tool, the present invention obtains a dynamic model that can reflect the dynamic characteristics of the machine tool, and performs start-stop shock characteristic analysis on this basis, quickly and conveniently identifying the dynamic error under the start-stop conditions of the whole machine tool.

[0062] As an optional embodiment, the start-stop shock characteristic curve includes an oscillatory decay characteristic curve. Correspondingly, judging whether the dynamic error curve of the tool tip relative to the workpiece meets the preset dynamic error index according to the start-stop shock characteristic curves corresponding to the tool tip and the workpiece respectively includes steps S310 - S320.

[0063] Step S310: Obtain the dynamic error curve of the tool tip relative to the workpiece according to the amplitudes of the oscillatory decay characteristic curves corresponding to the tool tip and the workpiece at the same time node.

[0064] Step S320: Judge 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.

[0065] Figure 3 a is a schematic diagram of the oscillatory decay characteristic curve of the tool tip under the start-stop conditions of the machine tool provided by the present invention. Figure 3 b is a schematic diagram of the oscillatory decay characteristic curve of the workpiece under the start-stop conditions of the machine tool provided by the present invention. As Figure 3 a and Figure 3 b show, the oscillatory decay characteristic curves corresponding to the tool tip and the workpiece respectively are oscillatory decay characteristic curves within a given time. The types of the three-dimensional oscillatory decay characteristic curves can be speed, acceleration, displacement, etc. under different excitations.

[0066] Figure 4 It shows the dynamic error curve of the tool tip relative to the workpiece obtained from the difference in amplitudes at the same time point according to the respective shock attenuation characteristic curves of the tool tip and the workpiece. The maximum amplitude value in the transient characteristic curve directly affects the geometric accuracy of the workpiece machined by the machine tool, and may cause the machining accuracy of the CNC machine tool to be unqualified. Therefore, the present invention determines the maximum amplitude of the dynamic error curve of the tool tip relative to the workpiece, and judges whether the maximum amplitude meets the preset dynamic error index. In the embodiment of the present invention, the type of the three-direction shock attenuation characteristic curve is taken as displacement for illustration, and the preset dynamic error index may be that the three-direction dynamic error of the tool tip relative to the workpiece under the maximum start-stop acceleration of 10 m / s 2 is controlled within 5 um That is, it is judged whether the maximum amplitude of the dynamic error curve is controlled within 5 um .

[0067] It can be understood that the present invention obtains the dynamic error curve of the tool tip relative to the workpiece through the respective shock attenuation characteristic curves of the tool tip and the workpiece, solves the problem that the machining accuracy cannot be guaranteed when the natural frequency and dynamic stiffness are used as the optimization objectives in the previous dynamic characteristic analysis, and can more accurately evaluate the dynamic characteristics of the CNC machine tool to ensure high-speed and high-precision machining of the CNC machine tool.

[0068] As an optional embodiment, performing modal analysis on the main body of the CNC machine tool according to the frequency-domain characteristic curve of the start-stop shock characteristic curve to determine the weak links of the main body of the CNC machine tool includes steps S330-step S350.

[0069] Step S330, determining the natural frequency corresponding to at least one frequency-domain peak value of the frequency-domain characteristic curve of the start-stop shock characteristic curve.

[0070] Performing Fourier transform on the respective shock attenuation characteristic curves of the tool tip and the workpiece respectively to obtain the respective shock attenuation characteristic Fourier transform curves of the tool tip and the workpiece, that is, the frequency-domain characteristic curves of the start-stop shock characteristic curve. According to the Fourier transform curves, the three-direction frequency-domain larger frequency-domain amplitudes and the corresponding natural frequencies of the tool tip and the workpiece can be obtained.

[0071] The number of target intercepts of the larger amplitudes in the frequency domain is selected after the dynamic error of the machine tool is evaluated. The start-stop shock characteristic of the machine tool is determined by the combined action of multiple modes. If the dynamic error exceeds the standard, the main modal frequencies causing the dynamic error to exceed the standard cannot be determined only through the time domain. Through the three-direction FFT transformation, the main modal frequencies causing the dynamic error to exceed the standard can be found, and then the corresponding modal vibration modes can be found. The main reasons for the appearance of this mode can be found through the strain energy, so as to perform targeted optimization. Such as Figure 5 a and Figure 5As shown in Figure 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 frequencies corresponding to the larger frequency domain amplitudes of the workpiece in the Y-axis direction are 4 Hz and 49 Hz.

[0072] Step S340: Perform modal analysis on the main body of the CNC machine tool to determine the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies.

[0073] Modal analysis includes, but is not limited to, analyzing the prestressed modes under conditions such as the temperature field, self-weight, and lead screw stretching of the main body of the CNC machine tool; performing modal analysis on the main body of the CNC machine tool to obtain the vibration modes and natural frequencies of each order of the machine tool within the frequency range of interest of the machine tool. Among them, the modal order ensures that the three-dimensional effective mass parameter coefficient of the machine tool is greater than 90%. The vibration modes corresponding to the natural frequencies are screened from the modal analysis results to ensure that the finite element analysis model has a sufficiently high accuracy. If the extracted modal order is insufficient, it cannot meet the analysis requirements.

[0074] Table 1 Natural frequency table of the first 9 orders obtained from the modal analysis of the machine tool

[0075] Among them, the peak frequencies of the tool tip and the workpiece correspond to the 3rd and 5th orders of the whole machine of the machine tool.

[0076] Step S350: Determine the weak links of the main body of the CNC machine tool according to the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies.

[0077] Optionally, the determining the weak links of the main body of the CNC machine tool according to the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies includes steps S351 - S352.

[0078] Step S351: Determine the strain energy of the structural components of the main body of the CNC machine tool at each of the natural frequencies according to the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies to construct a strain energy contour map.

[0079] Perform post-processing on the vibration modes of the structural components of the main body of the CNC machine tool at each of the natural frequencies to obtain the strain energy of the structural components of the main body of the CNC machine tool at each of the natural frequencies, and combine all the strain energies to obtain a strain energy contour map.

[0080] Step S352: According to the strain energy contour map, use the structural components with the strain energy reaching the preset value as the weak links of the main body of the CNC machine tool.

[0081] Optionally, the structural component with the maximum strain energy can be used as the weak link of the main body of the CNC machine tool.

[0082] It can be understood that during the machine tool design stage or the actual use process, the corresponding natural frequencies and modal vibration modes that affect the tool tip and the workpiece to generate large dynamic errors can be intuitively obtained, and on this basis, the weak links are identified, so as to carry out targeted dynamic optimization design.

[0083] As Figure 6 shown, as an optional embodiment, the optimization design scheme corresponding to the weak link includes but is not limited to topology optimization, dimension optimization, joint parameter optimization, damping parameter optimization, etc.

[0084] It can be understood that for the weak links that appear, the structure of the CNC machine tool is modified by combining joint parameter optimization, damping parameter optimization, etc., giving full play to the advantages of numerical simulation analysis in facilitating the modification of the geometric model and equivalent the dynamic characteristic parameters of the joints.

[0085] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0086] As Figure 7 shown, the present invention provides an optimization design method for a CNC machine tool based on the start-stop impact characteristics, including steps A - step J.

[0087] A. Define the dynamic error index under the design requirement acceleration.

[0088] B. Establish a finite element analysis model of the whole machine tool to obtain the dynamic model.

[0089] C. Conduct a transient dynamic characteristic analysis on the dynamic model.

[0090] D. According to the results of the transient dynamic characteristic analysis, determine the three-way start-stop impact characteristic curves of the tool tip and the workpiece under the preset working conditions.

[0091] E. According to the start-stop impact characteristic curves, evaluate the start-stop impact characteristics of the machine tool, and judge whether the start-stop impact characteristics of the machine tool meet the dynamic error index.

[0092] F. The start-stop impact characteristic curves include oscillatory decay curves. Fourier transform is performed on the oscillatory decay curves of the tool tip and the workpiece in the case where the dynamic error index is not met to obtain the Fourier transform curves.

[0093] G. According to the Fourier transform curves, determine the natural frequencies corresponding to the larger peaks in the frequency domain.

[0094] H. Combining with modal analysis, obtain information such as the modal vibration modes corresponding to different peak natural frequencies of the CNC machine tool.

[0095] I. Identify and optimize the weak links of the CNC machine tool.

[0096] J. Compare and verify the optimized results until a machine tool structure that meets the design requirements is obtained.

[0097] As Figure 8 shown, the present invention repeats step B-I until a machine tool structure that meets the design requirements is obtained. The optimization of the weak links includes the optimization of structural components and the optimization of joints. According to Figure 9 a- Figure 9 c, it can be seen that the dynamic errors of the machine tool structure optimized by the present invention in the X, Y, and Z directions are all improved.

[0098] The present invention analyzes and compares the dynamic performance of the optimized whole machine tool, can quickly predict the improvement effect, greatly saves the research and development cycle of the machine tool, and shortens the time for troubleshooting and other problems in the actual use process; ensures that the evaluation results are closer to actual production, thereby guaranteeing the geometric accuracy of machine tool processing. It plays a very good guiding role in the dynamic error assessment of the machine tool, the identification and optimization improvement of weak links, reduces the iteration times of machine tool versions, and improves the competitiveness of the machine tool in the market. In addition, the present invention also considers parameters such as the material physical properties of structural components and joint surfaces, establishes a dynamic analysis model that can reflect the actual machining accuracy of the machine tool, which is simple and convenient and has better universality; and can identify the weak links of the corresponding structures that affect the dynamic accuracy of the machine tool, and the analysis results are accurate, reliable, and persuasive, playing a very good guiding role in the optimal design of the machine tool; uses the convenient and fast finite element modeling technology to modify the weak links of structural components and process parameters, and directly obtains parameters such as the dynamic characteristics of the whole machine of the optimized machine tool, enhancing the universality and comparability of the dynamic error assessment results of the machine tool, providing technical support for the structural optimization and design of the whole machine tool, and greatly shortening the research and development cycle of the machine tool.

[0099] The following describes the numerical control machine tool optimization design device provided by the present invention. The numerical control machine tool optimization design device described below can be mutually referred to the numerical control machine tool optimization design method described above.

[0100] Figure 10 is a schematic structural diagram of the numerical control machine tool optimization design device provided by the present invention. As Figure 10 shown, the present invention also provides a numerical control machine tool optimization design device, including the following modules.

[0101] A construction module 1010 for constructing a dynamic model of the numerical control machine tool, where the dynamic model includes the main body of the numerical control machine tool, a tool provided on the main body of the numerical control machine tool, and a workpiece; An analysis module 1020 for performing transient dynamic characteristic analysis on the dynamic model to obtain the start-stop impact characteristic curves of the tool tip of the tool and the workpiece; A judgment module 1030, configured to judge whether a dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index according to start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively. If not, perform a modal analysis on the main body of the numerical control machine tool according to a frequency-domain characteristic curve of the start-stop impact characteristic curve to determine a weak link of the main body of the numerical control machine tool; An optimization module 1040, configured to return steps of constructing a 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 of the tool relative to the workpiece meets the dynamic error index.

[0102] As an embodiment, the start-stop impact characteristic curve includes a shock attenuation characteristic curve. Correspondingly, the judgment module 1030 is further configured to: Obtain a dynamic error curve of the tool tip relative to the workpiece according to amplitudes of the shock attenuation characteristic curves corresponding to the tool tip and the workpiece respectively at the same time node; Judge whether the dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index according to a maximum amplitude of the dynamic error curve.

[0103] As an embodiment, the judgment module 1030 is further configured to: Determine a natural frequency corresponding to at least one frequency-domain peak value of a frequency-domain characteristic curve of the start-stop impact characteristic curve; Perform a modal analysis on the main body of the numerical control machine tool to determine vibration modes of structural members of the main body of the numerical control machine tool at each of the natural frequencies; Determine a weak link of the main body of the numerical control machine tool according to the vibration modes of the structural members of the main body of the numerical control machine tool at each of the natural frequencies.

[0104] As an embodiment, the judgment module 1030 is further configured to: Determine strain energies of structural members of the main body of the numerical control machine tool at each of the natural frequencies according to the vibration modes of the structural members of the main body of the numerical control machine tool at each of the natural frequencies to construct a strain energy nephogram; Take a structural member with a strain energy reaching a preset value as a weak link of the main body of the numerical control machine tool according to the strain energy nephogram.

[0105] As an embodiment, the construction module 1010 is further configured to: Determine structural parameters and attribute parameters corresponding to the main body of the numerical control machine tool, the tool, and the workpiece respectively; Construct an overall finite element analysis model of the numerical control machine tool according to the structural parameters and attribute parameters corresponding to the main body of the numerical control machine tool, the tool, and the workpiece respectively. Configure the attitude and constraint conditions of the overall machine finite element analysis model to obtain the dynamic model of the CNC machine tool.

[0106] As an embodiment, the analysis module 1020 is further configured to: Determine the load type, load application position, damping parameter, duration, and step size for transient dynamic characteristic analysis; According to the load type, load application position, damping parameter, duration, and step size, perform single-axis or multi-axis linkage start-stop impact characteristic analysis on the dynamic model.

[0107] It should be noted that the CNC machine tool optimization design device provided by the present invention can execute the CNC machine tool optimization design method described in any of the above embodiments during specific operation, and has the corresponding technical effects of the method, which will not be elaborated in this embodiment.

[0108] Figure 11 An example of the physical structure diagram of an electronic device is shown as Figure 11 shown. The electronic device may include: a processor 1110, a communication interface 1120, a memory 1130, and a communication bus 1140. Among them, the processor 1110, the communication interface 1120, and the memory 1130 complete communication with each other through the communication bus 1140. The processor 1110 can call the logical instructions in the memory 1130 to execute the CNC machine tool optimization design method, which includes: constructing a dynamic model of the CNC machine tool, where the dynamic model includes the main body of the CNC machine tool, a tool provided on the main body of the CNC machine tool, and a workpiece; performing transient dynamic characteristic analysis on the dynamic model to obtain the start-stop impact characteristic curves of the tool tip of the tool and the workpiece; according to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively, determine whether the dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index. If not, perform modal analysis on the main body of the CNC machine tool according to the frequency domain characteristic curve of the start-stop impact characteristic curve to determine the weak link of the main body of the CNC machine tool; according to the optimization design scheme 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 of the tool relative to the workpiece meets the dynamic error index.

[0109] In addition, when the logical instructions in the above-mentioned memory 1130 are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or a part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The foregoing storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0110] On the other hand, the present invention also provides a computer program product. The computer program product includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the numerical control machine tool optimization design method provided by the above-mentioned various methods. The method includes: constructing a dynamic model of the numerical control machine tool, where the dynamic model includes the main body of the numerical control machine tool, a tool provided on the main body of the numerical control machine tool, and a workpiece; performing transient dynamic characteristic analysis on the dynamic model to obtain the start-stop impact characteristic curves of the tool tip of the tool and the workpiece; according to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively, determining whether the dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index. If not, performing modal analysis on the main body of the numerical control machine tool according to the frequency domain characteristic curve of the start-stop impact characteristic curve to determine the weak link of the main body of the numerical control machine tool; according to the optimization design scheme corresponding to the weak link, returning 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.

[0111] In another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the optimized design method for a numerically controlled machine tool provided by the above-mentioned various methods. The method includes: constructing a dynamic model of the numerically controlled machine tool, where the dynamic model includes the main body of the numerically controlled machine tool, a tool provided on the main body of the numerically controlled machine tool, and a workpiece; performing transient dynamic characteristic analysis on the dynamic model to obtain the start-stop impact characteristic curves of the tool tip of the tool and the workpiece; according to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively, determining whether the dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index. If not, performing modal analysis on the main body of the numerically controlled machine tool according to the frequency domain characteristic curve of the start-stop impact characteristic curve to determine the weak link of the main body of the numerically controlled machine tool; according to the optimization design scheme corresponding to the weak link, returning to the step of constructing the dynamic model of the numerically controlled machine tool until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

[0112] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative effort.

[0113] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on such an understanding, the above technical solutions, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disc, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the 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 invention.

Claims

1. An optimization design method for a numerically controlled machine tool, characterized in that, Including: Construct a dynamic model of a numerically controlled machine tool, where the dynamic model includes the main body of the numerically controlled machine tool, a tool provided on the main body of the numerically controlled machine tool, and a workpiece; Conduct a transient dynamic characteristic analysis on the dynamic model to obtain the start-stop impact characteristic curves of the tool tip of the tool and the workpiece; According to the start-stop impact characteristic curves corresponding to the tool tip and the workpiece respectively, determine whether the dynamic error curve of the tool tip relative to the workpiece meets a preset dynamic error index. If not, conduct a modal analysis on the main body of the numerically controlled machine tool according to the frequency-domain characteristic curve of the start-stop impact characteristic curve to determine the weak links of the main body of the numerically controlled machine tool; According to the optimization design scheme corresponding to the weak links, return to the step of constructing the dynamic model of the numerically controlled machine tool until the dynamic error curve of the tool tip relative to the workpiece meets the dynamic error index.

2. The optimized design method of the numerical control machine tool according to claim 1, characterized in that The start-stop impact characteristic curve includes an oscillation decay characteristic curve. Correspondingly, the step of determining whether the 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 includes: Obtain the dynamic error curve of the tool tip relative to the workpiece according to the amplitudes of the oscillation decay characteristic curves corresponding to the tool tip and the workpiece at the same time node; Judge 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.

3. The optimized design method of the numerical control machine tool according to claim 2, characterized in that The step of conducting a modal analysis on the main body of the numerically controlled machine tool according to the frequency-domain characteristic curve of the start-stop impact characteristic curve to determine the weak links of the main body of the numerically controlled machine tool includes: 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; Conduct a modal analysis on the main body of the numerically controlled machine tool to determine the vibration modes of the structural components of the main body of the numerically controlled machine tool at each of the natural frequencies; Determine the weak links of the main body of the numerically controlled machine tool according to the vibration modes of the structural components of the main body of the numerically controlled machine tool at each of the natural frequencies.

4. The optimized design method of the numerical control machine tool according to claim 3, characterized in that The step of determining the weak links of the main body of the numerically controlled machine tool according to the vibration modes of the structural components of the main body of the numerically controlled machine tool at each of the natural frequencies includes: Determine the strain energy of the structural components of the main body of the numerically controlled machine tool at each of the natural frequencies according to the vibration modes of the structural components of the main body of the numerically controlled machine tool at each of the natural frequencies to construct a strain energy nephogram; According to the strain energy nephogram, regard the structural components with strain energy reaching a preset value as the weak links of the main body of the numerically controlled machine tool.

5. The optimized design method of the numerical control machine tool according to claim 1, characterized in that, The step of constructing the dynamic model of the numerically controlled machine tool includes: Determine the structural parameters and attribute parameters corresponding to the main body of the numerically controlled machine tool, the tool, and the workpiece respectively; Construct a whole-machine finite element analysis model of the numerically controlled machine tool according to the structural parameters and attribute parameters corresponding to the main body of the numerically controlled machine tool, the tool, and the workpiece respectively; Configure the attitude and constraint conditions of the whole-machine finite element analysis model to obtain the dynamic model of the numerically controlled machine tool.

6. The optimized design method of the numerical control machine tool according to claim 5, characterized in that, The attitude 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 floor joint of the main body of the numerically controlled machine tool.

7. The optimized design method of the numerical control machine tool according to claim 1, characterized in that Performing transient dynamic characteristic analysis on the dynamic model includes: Determining the load type, load application position, damping parameter, duration, and step size for transient dynamic characteristic analysis; Performing 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, duration, and step size.

8. An optimized design device for a numerical control machine tool, characterized in that, Including: A construction module for constructing a dynamic model of a numerically controlled machine tool, where the dynamic model includes the main body of the numerically controlled machine tool, a tool provided on the main body of the numerically controlled machine tool, and a workpiece; An analysis module for performing transient dynamic characteristic analysis on the dynamic model to obtain the start-stop impact characteristic curves of the tool tip of the tool and the workpiece; A judgment module for judging whether the 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 main body of the numerically controlled machine tool according to the frequency domain characteristic curves of the start-stop impact characteristic curves to determine the weak links of the main body of the numerically controlled machine tool; An optimization module for returning to the step of constructing the dynamic model of the numerically controlled machine tool according to the optimization design scheme corresponding to the weak links until the dynamic error curve of the tool tip of the tool relative to the workpiece meets the dynamic error index.

9. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the numerically controlled machine tool optimization design method according to any one of claims 1 to 7.

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

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