Simulation And Optimization Of VMC850B Dynamic Characteristics Of CNC Machine Tools

Machinery manufacturing industry is the foundation of national economy.With the development of information technology and advanced manufacturing technology,the application of NC machine tools is more and more extensive.Therefore,the manufacturing industry in China has higher and higher requirements for the machining accuracy and quality of NC machine tools.The research shows that the dynamic characteristics of machine tools have a great influence on the machining accuracy of machine tools.Therefore,the dynamic characteristic simulation test and optimization of NC machine tools become an effective method to improve the processability of machine tools.This paper takes the VMC850B CNC machine tool produced by Shenyang Machine Tool Group as research object,carries on the hammering method experimental modal analysis,carries on the theoretical analysis and the topological optimization design using Ansys workbench software to the vertical column,finally carries on the dimensional sensitivity analysis to the sliding seat of the machine tool,on the basis of guaranteeing the dynamic characteristic,the quality is reduced.The main contents and conclusions of this paper are as follows:(1)Summarize the main research methods and predecessors'work on the dynamic characteristics of the whole machine,discuss the application and research of the parameter identification of the machine tool interface and the topological optimization design of the machine tool structure at home and abroad,and study the necessity of the dynamic characteristics analysis of the vertical machining center.(2)Based on the theory of structural dynamics,the dynamic response of the machine tool is analyzed;the equivalent model of the fixed and sliding interface of the machine tool is established by using spring-damping element,and the damping and stiffness of the interface are applied to the finite element model of the machine,which established foundation for the subsequent analysis of the dynamic characteristics of the machine tool.The simulation model can not only predict the actual processing situation,but also provide a reference for the performance optimization of machine tools.(3)First,single-point excitation multi-point response method is used to carry out experimental modal analysis of the whole machine;Then the frequency domain modal parameter identification method is used to extract the parameters.Finally,the natural frequency,damping and mode parameters of the whole machine are obtained,and the weak parts of the whole machine are obtained as column by analyzing the experimental data,which established foundation for the structural optimization design of the machine tool.(4)Finite element analysis of the whole machine is carried out,and the reliability of the finite element model is verified by comparing the results of experimental modal analysis.According to the results of column topology optimization,the stiffened plate of column are optimized.On the basis of ensuring the quality of the whole machine,the static and dynamic performances of the columns before and after optimization are compared,and the results show that the optimized structure is feasible.(5)Firstly,the static and dynamic characteristics of the sliding seat of the key component of the machining center are analyzed,then the static deformation,the first six natural frequencies and the corresponding vibration modes are obtained under the actual working conditions.Then,the dimension parameters of the sliding seat are optimized by response surface method using three-dimensional software UG and ANSYS workbench.The optimization results show that,without affecting the static and dynamic characteristics of the whole machine,the total mass of the sliding seat is reduced by 8.7%,which not only reduces the cost of the whole machine,but also improves the flexibility and load capacity of the machine tool system.