Study On Chatter Stability Of Titanium Alloy Impeller Based On Process Damping Effect In Turning-milling

The impeller plays an important role in aero-engine.The dimension accuracy and surface quality determine the performance and service life of the engine.Titanium alloys are widely used because of the high strength and light weight.Titanium alloys are difficult to be machined and its poor machinability leads to chatter in the process of machining.The surface quality caused by this phenomenon can’t be guaranteed.Therefore,the study on chatter stability of impeller in turn-milling process is worth to be paid more focus in the field of mechanical engineering.Based on the problem of chatter stability of titanium alloy impeller in machining process,the cutting force,process damping and the chatter stability of impeller in turn-milling are modeled respectively in this paper and the influence of process damping on the prediction model of chatter stability is mainly considered.Process damping effect is often caused in cutting process.It is often neglected in most chatter stability studies due to the complexity of model.However,with the increase of tool wear,the process damping effect becomes more and more obvious.Therefore,the process damping factor is considered in the stability model to improve accuracy.The specific research contents of this paper are as follows:(1)The cutting force of ball-end milling cutter in multi-axis turn-milling process is modeled.The influence of tool inclination angle is considered and the cutting force is simulated.Meanwhile,the identification model of milling force coefficients of ball-end milling cutter is established.The milling force coefficients are obtained by groove milling on NC machine tools.Besides,the validity of the cutting force model is verified by comparing the experimental cutting force with the simulated results.(2)The process damping model is established.According to the relationship between process damping force and the indentation area,the calculation method of process damping force is obtained by computing the indentation area.Additionally,by means of energy equivalence,the nonlinear process damping force is equivalent to the linear process damping force,and the process damping coefficient is identified.Finally,the influence of cutting parameters on the process damping coefficient is analyzed.(3)Considering the effect of process damping on the stability,the regenerative chatter model is established for turn-milling the titanium alloy impeller.The multi-frequency method is used to solve the dynamic equation of the tool-impeller machining system,and the chatter stability prediction model is obtained.According to modal parameters obtained through modal experiment,stability lobes is simulated.The accuracy of the model is verified by different parameters in the process of impeller machining.(4)The surface quality of impeller is completed and the influence of different machining parameters on the surface quality is analyzed.The chatter stability model is designed as a user interface through the GUI module in MATLAB,and the predicted lobes diagram can be acquried by inputting parameters,which makes the model established in this paper more convenient for application.