Research On Chatter Stability Of Milling Process Based On Rényi Entropy

As an efficient cutting method,milling has a wide range of applications.Whether it is rough machining,finishing,or is widely used in aviation,aerospace,automobile manufacturing and other fields,milling can be seen everywhere.However,in the process of milling,the cutting chatter caused by the characteristics of the machining system itself will seriously affect the quality and efficiency of milling.Chatter refers to the phenomenon of self-excited vibration caused by the characteristics of the machining system in the cutting process.Whether chatter directly affects the surface quality of parts,damages the cutter teeth or the machine tool spindle,or the cutter teeth or the machine tool spindle,chatter will have a serious impact on it.The most effective way to avoid chatter is to select the cutting parameters according to the chatter stability lobe diagram.In this paper,a new method for predicting chatter stability is proposed,which uses the time domain simulation data of milling process,and realizes the prediction of stability lobe diagram by a new time domain stability discrimination method.The main research contents are as follows: in order to realize chatter free milling,the most effective method is to carry out dynamic modeling of the cutting process,solve and judge its stability,draw chatter stability lobe diagram,and select parameters from it,so as to realize chatter free milling.Among all the methods,the numerical method has the highest prediction accuracy,but the criterion of the numerical method is not universal,so it needs to be improved.The main contents of this paper are as follows:Firstly,considering the regenerative effect in the milling process,the dynamic differential equation of milling process is established.On this basis,the Runge Kutta method with variable step size is used to solve the dynamic differential equation of milling process,and the time-domain signals such as cutting force and tool tip amplitude are obtained.The differences between the two methods are compared,and then the Runge Kutta method with variable step size is solved through a simulation example The results were verified.Secondly,in order to solve the problem of generality of time-domain stability criterion,Rényi entropy,Shannon entropy and Sevick dimension are used to detect and analyze the cutting signal and chatter signal in the stable cutting stage,to judge whether it can judge the chatter timely and accurately,and to judge the chatter The appropriate method is used as the criterion of chatter stability,and the threshold of chatter occurrence is determined.Based on MATLAB platform,the time domain simulation interface of chatter stability in milling process is developed,and the lobe diagram of chatter stability is drawn to realize the accurate prediction of chatter stability in milling process.Finally,the chatter verification test is carried out,and the test results are compared with the simulation results.The hammer test and cutting force coefficient identification test are carried out to obtain the machine tool modal parameters and cutting force coefficient required by the simulation.The results of cutting experiments are compared with the chatter stability lobe diagram,which verifies the accuracy of the time-domain stability solution method and stability criterion proposed in this paper.The feasibility of the selected chatter identification method and the accuracy of the threshold are analyzed.