Chatter System Dynamic Characteristics Analysis

Machining chatter is an intensive and relative vibration, a kind of self-excited vibration between the cutting tool and the workpiece in cutting processes. It is of significant importance to analyze and control chatter because it decreases the efficiency of processing and cutting, shortens life expectancies of cutting tools and machine tools and inevitably brings about noise pollution, even results in great accidents and casualties.Firstly, fundamental conceptions of dynamic system and linear theory of cutting vibration are mentioned, which is used as the mainstay of nonlinear theory in the dissertation. The conceptions of balance point, limited cycle and their stability are introduced as the basis of the author's discussion on the properties and mechanism of self-excited vibration. In the cutting process, because of the different qualities and means of feedbacks, there are different types of vibration and instability. Linear models about velocity feedback, displacement feedback and mode coupling are given and their mechanisms are analyzed fully.Secondly, achievements of nonlinear vibration are explained. By introducing a non-linear cutting vibration model put forward by some experts, which is about the non-linear stiffness, the achievements, problems and difficulties of the model are pointed out. Then by presenting the nonlinear factor of cutting tool out of the workpiece, a new nonlinear model is made and analyzed which leads to the conclusions, such as amplitude stability and influence of cutting parameters on the cutting vibration and so on. After that, we make a perfect model according to two essential non-linear factors: non-linear stiffness and the cutting tool out of the workpiece .This model gives some clues about two phenomena: amplitude stability and limited amplitude instability.Lastly, we verify the non-linear model through experiments and it shows that the results of the experimental analysis are in accordance with the conclusions of theory. In the mean time, we reveal the whole process of cutting vibration through the non-linear data model and emulation. In order to predict and control vibration, we study the influence of cutting value on vibrations, so that theoretical basis is provided to detect and control vibration online in blisk NC machining.