The Study Of Dynamic Stability And Model Of Boring Bar

Metal cutting is an important process of mechanical manufacturing technology. But cutting vibration often decreases the processing quality of work piece. Cutting chatter, one of the cutting vibrations, has direct and key impact on metal cutting. Boring is an important method of inner hole process. However, the poor stiffness of boring bar can lead to cutting chatter, which can damage machining surface easily.The core content of this thesis has two parts: the analysis of the dynamic stability of boring bar and the study of the dynamic model of the vibration absorption boring bar. The aim of this thesis is to provide theoretical basis for monitoring, prevention and reduction on boring chatter. The main content of this thesis includes the following parts:Based on Euler-Bernoulli beam theory, the linear dynamic model of regenerative chatter of boring bar is established. The dynamic stability of regenerative chatter of boring bar is analyzed. The dynamic stability diagram of boring bar is obtained. Based on dynamic stability diagram, the impact of spindle speed, boring bar damping ration and cutting stiffness coefficient on dynamic stability of regenerative chatter of boring bar is analyzed.Base on the linear dynamic model of regenerative chatter of boring bar, the nonlinear dynamic model of regenerative chatter of boring bar is established, including the nonlinear relation between cutting force and cutting thickness. The dynamic stability is studied. The condition of critical stability of linear dynamic and the cutting chatter amplitude are obtained.Based on Euler-Bernoulli beam theory and non-uniform beam theory, the dynamic model of vibration absorber boring bar based on intelligent magnetorheological(MR) fluids is set up. The rigid-flexible coupling dynamic model of vibration absorber boring bara based on intelligent MR fluids is established by Automatic Dynamic Analysis of Mechanical Systems(ADAMS). Through control variate method, the dynamic characteristics of two kinds of method are being contrasted respectively when excitation frequency and intelligent MR fluids damping are changing. The result shows that the dynamic model of vibration absorber boring bar which is based on Euler-Bernoulli beam theory and non-uniform beam theory is reasonable.