Research On Milling Force Modeling And Milling Cutter Optimization

Thin-walled rib is an important component to ensure the strength of rocket fuel tank,which vibrates easily during milling process because of the property of thin wall.Thin-walled parts have become a hot research topic in manufacturing field.This paper researches on the milling of thin-walled parts,focusing on vibration suppression cutter.On one hand,a milling force analytical model is established,which is suitable for variable helix end mill.On the other hand,the structure of milling cutter is optimized.The main contents are as follows:(1)Based on the cutting mechanism,a milling force analytical model is established connecting cutting parameters,cutter structure with cutting forces during the cutting process,which considers the pitch angle and the helix angle of each flute.The helical flutes are decomposed into a set of infinitesimal oblique cutting edges.Three-dimensional infinitesimal oblique cutting model is established based on energy method,expressing the relation of infinitesimal cutting angles,cutting velocities and differential cutting forces clearly.By integrating the differential cutting forces along each cutting edge,which considers the effect of the feed velocity,static milling forces can be predicted.Considering regenerative effect,dynamic forces can be predicted.(2)Applying the theory of milling force model established,the pitch and cutting thickness of variable end mill are analyzed,and the trend of cutting forces with variable end mill is obtained.Transforming milling forces from time domain to frequency domain by Fourier transform,the vibration suppression mechanism of variable end mill is elaborated.Based on the even distribution of milling forces in frequency domain,the structure of variable end mill is optimized.The mathematical model is established,with even distribution of milling forces in frequency domain as the main goal,with cutting force,cutting heat and balance of end mill as the constraints.Optimal pitch angle and helix angle are obtained by the application of genetic algorithm.Specific structure of variable helix end mill is designed.Optimal design of end mill is checked by finite element software.(3)Milling force experimental program is designed.Milling tests with equal pitch end mill and variable pitch end mill are conducted.The simulated and measured cutting forces match well.It proves the accuracy of milling force model established.The optimal design variable end mill is machined.Thin-walled parts milling vibration tests with optimal design variable end mill and equal pitch end mill are conducted to certificate the reliability from milling vibration displacement and frequency domain of milling force.