The Dynamic Characteristics Evaluation And Optimization Design Of The Dual-drive Feed System

With the continuous development of machine tools towards high speed and high accuracy at home and abroad,the dynamic performance of machine tools is increasingly demanding.As the core part of machine tools,feed system has a direct impact on the performance of machine tools.Taking the feed system of MCH63 machining center as the research object,the following aspects are studied in the following aspects:dynamic characteristic evaluation of feed system,establishment of dynamic mathematical model,finite element modeling analysis,modal test and structural parameter optimization.First,the dynamic performance evaluation system of machine tool feed system is set up from the aspects of vibration resistance and transient response performance.The judgment matrix and evaluation matrix are established by intuitionistic fuzzy analytic hierarchy process(AHP),and the MCH63 NC machine tool is evaluated.The evaluation results show that the evaluation grade of the comprehensive dynamic performance of the machine tool is "good",and the membership degree is 32.78%.Secondly,the dynamic mathematical model of multi degree of freedom of machine tool feed system is established.The expression of kinetic energy,potential energy and energy dissipation equation of the feed system is established by using the energy method,and the differential equation of vibration is derived by the Lagrange equation.The first six order natural frequencies of the machine tool are obtained by solving the differential equation.The finite element method and modal test are used to verify the differential equation of vibration.The maximum error is 11.3%,which shows the correctness of the modeling method.By solving the vibration differential equation,the relationship between the structure parameters of the machine tool and the natural frequency is obtained.The results show that the axial stiffness of the screw nut,the axial stiffness of the bearing,the diameter and length of the screw and the position of the worktable have a great influence on the first natural frequency,and the influence of the weight of the worktable,the span of the guide rail and the contact stiffness of the slideway and the slider on the natural frequency value is related to the modal shape.Finally,taking the weight of the worktable,the contact stiffness between the slideway and the slider,the axial contact stiffness between the screw and nut,the axial stiffness of the bearing,the diameter of the lead screw and the length of the screw rod as the design variables,and tanking the optional speed range of the spindle of the machine tool as the optimization target.Three sets of optimized parameters are obtained by genetic algorithm optimization.The optimized spindle speed of the machine tool can be chosen arbitrarily in the range of 4000r/min?5000r/min and will not be affected by resonance,so the dynamic performance of the machine tool can be improved.