Experimental And Simulation Research On Meso-scale Machining Process Of Al7075Base On MSG Theory

There is a growing need for micro parts in the aerospace, micro-electronics,environment, communications, automotive, biotechnology and many other fields, soscholars pay attention to the phenomena and mechanisms of meso-scale cutting process.Meso-scale cutting is not just the size reduction of macro-scale and the new theoretical andtechnological problems were put forward, for example the size effect and the minimumthickness of cutting. Traditional plasticity mechanics theory can not describe the straingradient effect in meso-scale cutting process, so micro plasticity mechanics theory andmaterial dislocations have to be put forwarded for simulation analysis and experimentalresearch.The material constitutive model based on the mechanism-based strain gradient (MSG)plasticity theory is established to describe the mechanical behavior of materials, which canrepresent size effect in meso-scale cutting process; ABAQUS FEM material subroutine isdeveloped by Fortran based on the material constitutive model; Using an arbitraryLagrangian-Eulerian (ALE) adaptive meshing technique, a2D dynamical modle for themeso-scale machining process is built and verified by the orthogonal milling experiments.With the simulation model, minimum chip thickness, specific cutting force, strain gradienteffect and equivalent stress are studied for the meso-scale cutting process of aluminum.The results show that the modified constitutive model can effectively predict themeso-scale cutting process based on the mechanism-based strain gradient plasticity theoryand it is closer to the experimental values about cutting force and cutting force units thanthe classical JC model. Minimum chip thickness is dependent on the tool edge radius andsuggested to be about0.25to0.3times of cutting edge radius for cutting aluminum withPCD tools; The strain gradient are found to be the main cause of the size effect ofmeso-scale machining and the specific cutting force and cutting force significantlyincreases as the uncut chip thickness decreases; The maximum stress of the cutting areadecreases as cutting velocity increases and the maximum stress of the cutting area increasesas rake angle and the tool edge radius increases; Cutting speed has small effect on thecutting force, the cutting force decreases as rake angle increases and the cutting forceincreases as the tool edge radius increases.