Constitutive Relationship Modeling And Cutting Force Model In Milling Of Al-50wt%Si Alloy Considering Particle Effects

With its excellent comprehensive performance such as high thermal conductivity and low coefficient of expansion,Al-50wt%Si alloy meets the development requirements of increasingly miniaturized,lightweight and high power density of electronic packaging modules,and is being used more and more widely in electronic equipment at home and abroad.Milling as one of the most important material removal methods,milling is widely used in the manufacturing process of Al-50wt%Si alloy parts.Since the cutting force has an important influence on the surface roughness of the parts,tool life,and cutting energy consumption,it is especially important to control the cutting force reasonably.By theoretical modeling of cutting forces during milling,it is important to provide theoretical guidance for achieving reasonable control of cutting forces,which will help reduce the cost of optimizing the machining process of Al-50wt%Si alloy parts.The machining process of cutting is a violent impact deformation process that contains large strains and high strain rates.In order to achieve a reasonable prediction of the cutting force in Al-50wt%Si alloy milling,this paper first carried out a study of the mechanical properties of Al-50wt%Si alloy under high-speed impact loading.The particle strengthening and damage softening effects were found to exist in Al-50wt%Si alloy under high speed impact loading.The intrinsic constitutive equations of Al-50wt%Si alloy at high strain rate and high temperature were established based on Eshelby’s equivalent inclusions theory and Weibull damage estimation model considering the particle effect.Meanwhile,the correlation coefficient between the intrinsic constitutive equations and experimental results was calculated to be 0.992 with an average relative error of 4.93%,indicating that the proposed intrinsic constitutive model can better describe the rheological behavior of Al-50wt%Si alloy under high speed impact loading.Secondly,during the milling of Al-50wt%Si alloy,the cutting edge of the helical milling cutter is considered as bevel cutting,and the transient cutting process is analyzed based on the bevel cutting model,and the intrinsic constitutive equation of Al-50wt%Si alloy considering the particle effect established earlier is used to construct a chip formation force model for milling Al-50wt%Si alloy with the helical end mill considering the particle effect.The tool-chip interface friction in Al-50wt%Si alloy machining is considered to be composed of three contact regions,including two-body sliding contact,three-body rolling contact and substrate adhesion contact.Based on the friction model of the above three contact regions,the theoretical model of friction force and friction coefficient for milling Al-50wt%Si alloy is constructed.Finally,the milling force model for milling Al-50wt%Si alloy was established by combining the chip formation force model of the bevel cutting theory and the friction force model based on the three-phase friction model.Finally,the milling force model of Al-50wt%Si alloy considering the particle effect is experimentally validated.The results show that the established milling force prediction model can predict the Al-50wt%Si alloy milling force well.At the same time,the influencing factors of the three milling fractional forces were analyzed,including the influence law and mechanism of each milling parameter on each milling fractional force.The results show that the cutting parameters affecting the milling forces are mainly: axial depth of cut and feed per tooth.The milling forces in all three directions increased significantly with the increase of feed and axial depth of cut,and the milling forces in the three directions of Al-50wt%Si alloy did not change significantly with the change of spindle speed.This phenomenon can be attributed to the combined effect of strain-rate hardening properties and strain-rate dependent damage softening properties.