Research On Dynamic Characteristics Of Turning Tool Bar System Based On Damping And Vibration Reduction

With the proposal of "made in China 2025",China's manufacturing industry once again based on a new starting point,which puts forward higher requirements for the field of mechanical processing.When machining the parts of the rotating body,the turning process has been widely used because of its unique processing mode.But in the process of turning,vibration will occur due to the influence of system structure.Chatter is a kind of violent self-excited vibration among lathe,workpiece and tool in the cutting system.The chatter of lathe has a great influence on the quality of workpiece.In this paper,based on the principle of damping vibration reduction,the dynamic model of constrained damping single degree of freedom and impact damping two degree of freedom vibration reduction turning tool bar is established.The influence of system parameters on the vibration characteristics of the system is numerically simulated.The bifurcation diagram,phase diagram and Poincaré section diagram of the system are analyzed in detail through the chaos bifurcation theory.which provides a theoretical basis for parameter selection and optimization during actual cutting.The details are as follows:Taking constrained damping vibration reduction lathe tool bar system as the research object,the single-degree-of-freedom dynamic model is established.The dynamic equation is obtained by Newton's second law and lumped mass method and dimensionless.The equation of state is simulated numerically.After a lot of simulation,the bifurcation diagram,phase diagram and Poincaré section diagram are obtained by selecting certain parameters to analyze the motion of the system The stability of the system is judged by the largest Lyapunov exponent.It is found that the system is dominated by chaos at low frequency and low damping.With the increase of harmonic force frequency and constrained damping value,some conventional bifurcation behaviors occur,such as period doubling and counter-period doubling bifurcation,Neimark-Sacher bifurcation,and periodic bubble structure appears.When the constraint stiffness is taken as the bifurcation parameter,the system is dominated by periodic motion at low value,and the chaotic window increases with the increase of the constraint stiffness.Taking the impact damping and vibration reduction tool bar system as the research object,the two-degree-of-freedom dynamic model is established.The dynamic equations are obtained by Newton's second law,the law of conservation,and the law of collision,then dimensionless.The effects of exciting force frequency,clearance,mass ratio and stiffness coefficient on the chaotic characteristics of the system are numerically simulated.It is found that when the gap is small,it is the mutual transformation of periodic and chaotic motion.With the increase of the gap,the system presents the characteristics of periodic motion.When the mass ratio changes,the system presents chaotic motion in most intervals and chaotic bubble structure appears.With the change of exciting force frequency and stiffness coefficient,multiple attractors coexist in the system and keep in the process of attractor contraction and expansion for a long time,showing complex dynamic characteristics.