Milling Stability Analysis And Process Parameter Optimization Based On Fillet-end Milling Cutter

Milling is an important machining method,which is widely used in aerospace,automobile manufacturing,die manufacturing and other fields.However,in the process of milling,due to the improper selection of processing parameters,chatter easily occurs in the process of milling,resulting in the instability of milling.Chatter will cause tool damage and decrease the accuracy of workpiece surface processing.In order to avoid chatter and achieve high efficiency and high precision,it is necessary to study the stability of milling process thoroughly and systematically.In this paper,the stability of fillet-end milling cutter in processing 7075 aluminium alloy is studied by means of MATLAB simulation,finite element analysis and experiment,and the processing parameters are optimized by genetic algorithm to meet the requirements of high efficiency and precision.The main contents of this paper are as follows:Firstly,The cutting force model of fillet-end milling cutter is established.The cutting edge of the fillet-end milling cutter is discretized into several tiny cutting edges along the cutter axis.Based on the oblique cutting model,the instantaneous rigid mechanical cutting force model of the fillet-end milling cutter is established.The five-axis cutting force model of annular milling cutter is established by coordinate transformation.Secondly,the dynamic model of fillet-end milling cutter is established.On the basis of cutting force model,considering the dynamic cutting thickness caused by regenerative chatter effect,and considering the vibration of tool system and workpiece system respectively,the dynamic model of annular milling cutter is established.The modal parameters of the tool system are obtained through the modal experiments of the laser vibrometer and the force hammer.The first natural frequencies and modes obtained are compared with the first natural frequencies and modes obtained by the finite element simulation,and the correctness of the finite element model is verified.Thirdly,the solution method of milling stability.Referring to the idea of numerical integration method,a numerical method based on 3/8 Simpson formula is proposed to solve the milling stability.Under the single DOF milling model and the two DOF milling model,compared with the first-order semi-discrete method and the second-order full-discrete method,the proposed method has higher accuracy and efficiency.The validity of the proposed method is verified by stability experiments.Finally,optimization of milling process parameters.stability and processing parameters are proposed as constraints,maximum material removal rate and minimum surface roughness as optimization objectives,and genetic algorithm is used to optimize milling process parameters(spindle speed,feed rate,axial and radial depth of cut)to achieve high efficiency and high precision processing requirements.