Research Of Cutting Chatter Suppression Based On Intelligent Control Strategy

Cutting chatter is a strongly relative vibration occurring among machine tool, cutting tool and workpiece. In mechanical processing, it not only affects the machining accuracy of workpiece and reduces the machining efficiency, but also leads to the damage of machine parts and cutting tools, increases noise and pollution of the environment. Especially in high speed and high precision machining process, cutting chatter is of great harm and it is necessary to suppress it.Passive control is traditional in cutting chatter control methods. Using method of active or semi-active actuator to suppress chatter has developed with the progress of new sensors, advanced technology of signal processing and the emergence of modern control theory in the past30years. The research of active and the semi-active control technology on cutting chatter has made certain achievements at home and abroad so far.The main work of this paper is about the research on cutting chatter model of concentrated mass system and continuous mass system and the method using piezoelectric intelligent material combining with BP neural network PID control to suppress chatter.Firstly, stability condition of system is analyzed based on occurrence mechanism of cutting chatter and differential equation of cutting chatter with concentrated mass. The close relationship between limit cutting width and cutting stability is discussed, the influence of various system parameters on chatter stability is also discussed as theoretical basis of weakening chatter. Simulation of cutting chatter signal in time domain is accomplished through MATLAB/SIMULINK, and the correctness of the theory analysis conclusion is proved. Further calculation formula of minimum limit of cutting width is derived.Then, the boring bar and boring can be looked as cantilever beam structure excited by chatter excitation considering the limitation of lumped parameter model on the background of boring chatter suppression problem. At the same time, a piezoelectric smart beam is formed when pasting piezoelectric patches on the boring bar in order to realize the active suppression of cutting chatter. Dynamics modeling of piezoelectric intelligent cutting chatter suppression system with distributed mass is built through combining the vibration differential equation of piezoelectric sensor actuator and cantilever beam. Using transfer matrix method to solve vibration modal of stepped beam after pasting piezoelectric patches and analyzing the impact of piezoelectric element size, location and quantity on beam characteristics are further discussed.Finally, the intelligent control strategy which combining BP neural network combined with classical PID control is focused on, it can be found that the strategy possesses the advantages of both PID and BP neural network based on the theory analysis and derivation, which provides a new method for intelligent control of cutting chatter. Traditional PID and PID control of BP neural network are used respectively to control the piezoelectric intelligent cutting chatter suppression system in MATLAB. Analysis result shows that PID control of BP neural network is more effective and adaptive compared with classic PID control.