Research On Dynamic Modeling Of Double Flexible Milling System And Stability Of Blade Processing

Thin-walled titanium alloy parts represented by aero-engine blades are widely used in aerospace and other fields because of their light weight and high specific strength.However,the weak rigidity of thin-walled parts,the difficulty of cutting materials,and the regenerative effect of the milling process during machining can easily lead to the instability of the process system and chatter,which in turn reduces the machining accuracy and surface quality of the workpiece.In view of the chattering problem of milling,the stability of the process system is studied.The main work is as follows:(1)Research on dynamic modeling of double flexible milling and solution of stability domain.The milling process system is classified,and the single flexible and double flexible process system models are established respectively.For the milling of thin-walled parts,a double flexible process system that considers the machine tool tip point and the dynamic characteristics of the workpiece is proposed.The cutting force model of the ball-end milling cutter is established.The improved frequency domain zeroorder component method and the time-domain semi-discrete method are used to study the milling stable domain solution method,which provides a theoretical basis for ensuring that the milling process remains in the stable region.(2)Analysis of dynamic characteristics of milling technology system considering material removal.Based on the analysis of the principles and methods of modal research,a matrix perturbation method considering the material removal to obtain time-varying dynamic parameters is proposed for the dynamic characteristics of the thin-walled workpiece subsystem.By segmenting the blade finishing process,the rapid acquisition of time-varying dynamic parameters of the workpiece is achieved.And obtain the corresponding stable leaflet maps in different stages,which provides a reliable theoretical basis for the optimization of the processing parameters of the blade.Establish a modal hammering experiment platform,and obtain the dynamic parameters of the machine tool tip point.(3)Cutting force modeling and identification of titanium alloy cutting force coefficients.Based on the analysis of the cutting force coefficient identification strategy and principle,the identification model was established,and the corresponding average cutting force was obtained through the slot milling experiment of titanium alloy parts under different process parameters.Based on the equivalent relationship between the experimental value and the theoretical value of the cutting force,the cutting force coefficient of the titanium alloy material was obtained by the least square method.(4)Titanium alloy blade milling stability experiment.Based on the modal simulation analysis and the hammering experiment method,the input parameters of the milling stability model,that is,the dynamic parameters of the titanium alloy blade,are obtained.Use the theory proposed in this paper to obtain the milling stability leaflet map.Using VERICUT machining simulation software to simulate the blade milling process,the correctness of the NC program was verified.Through the actual milling experiment,the validity of the milling stability model established in this paper is verified.