Dynamic Characteristics Analysis And Optimization Design Of Dynamic Damping Boring Bar

Deep hole boring is a difficult problem in the field of mechanical processing.The long overhang length reduces the stiffness of boring bars and results in chatter.Dynamic damping boring bar is an effective approach to avoid chatter in deep hole boring.In this paper,a simplified dynamic model of damping boring bar is established,and the relevant equivalent parameters of the model are identified.The results of experimental studies are shown that the different dynamic characteristics between domestic boring bars and foreign boring bars.The model of dynamic cutting process system is built,and the stability of the boring bars is analyzed using MATLAB Simulink software.To improve the chatter stability,optimum parameters of the vibration absorber and optimum length of mass block are designed.Moreover,the accurate finite element model of Dynamic damping boring bar is established for dynamic simulation analysis.The main contents in this paper are as follows.(1)The structure of dynamic damping boring bar is designed,and its simplified dynamic model is established.Based on the beam theory and energy conservation principle,the equivalent parameters of the model are identified,and then validated through ABAQUS finite element simulation.According to the traditional design method of vibration absorber,the design parameters of vibration absorber built in boring bar are calculated,and the vibration response characteristics are analyzed.(2)Modal experiments and cutting experiments are carried out between domestic boring bars and foreign boring bars.According to the experimental results,the differences in dynamic characteristics and its reasons are found,and some useful plans are proposed to improve the domestic boring bars.(3)Based on the regenerative chatter principle,a time-delay closed-loop dynamics model for the dynamic cutting process is established for analyzing the chatter stability of boring bar and drawing the stability lobe diagram.MATLAB Simulink software is used to simulate the dynamic cutting process of dynamic damping boring bar.And the simulation results show that the chatter stability can be presented by limited cutting width.(4)In order to improve the chatter stability,the optimal design formulas for the vibration absorber parameters are derived,which improving the stability by 102% compared with traditional method.Moreover,the optimum length of mass block are designed using MATLAB,and the stability is increased by 18%.Using ABAQUS software,the accurate finite element model of Dynamic damping boring bar is established for dynamic simulation analysis.And the simulation results are compared with theoretical calculations and experimental results to verify the finite element model.