Finite Element Simulation And Experimental Study On Diamond Cutting Of Curved Surface Of Crystalline Copper

Ultra-smooth surface is a key factor to improve the performance of metal parts,and ultra-precision diamond cutting is an important method to prepare ultrasmooth metal surface.Metal parts include not only flat surfaces,but also various curved surfaces.At present,the processing of ultra-smooth metal flat surfaces has been realized.However,how to use diamond cutting to process ultra-smooth metal curved surfaces needs to be solved urgently,which is one of the frontiers and hot topics of current international research.In ultra-precision cutting,the mechanical properties and deformation behavior of microstructures inside the metal material will have a serious impact on machined surface quality.Therefore,it is necessary to use simulation and experimental methods of micro-scale material removal to deeply study the ultra-precision machining of ultra-smooth curved surfaces.This thesis takes diamond cutting of crystalline copper curved surfaces as the research object,and conducts below research work through the combination of crystal plastic finite element simulations and experiment of ultra-precision diamond cutting.The establishment of a two-dimensional finite element model of diamond cutting of a crystalline copper curved surface is the technical basis for the subsequent simulation research.In the finite element simulation model,the crystal plastic constitutive model based on the dislocation slip theory is used to describe anisotropic deformation behavior of various microstructures of the crystalline copper under ultra-precision cutting.The formation of chips during metal cutting is simulated by the Jahnson-Cook damage model combined with element deletion technology.Based on the two-dimensional finite element model,finite element simulations of diamond cutting of crystalline copper curved surface are carried out.By processing the results obtained from finite element simulations,a comprehensive analysis is conducted in terms of chip morphology,stress field distribution,cutting force,residual stress distribution on the surface,and surface roughness.The diamond cutting processes of single crystal copper and bi-crystal copper curved surface are studied systematically.In order to obtain the influence mechanism of processing parameters on the cutting process of crystalline copper curved surfaces,a comprehensive finite element simulation study is carried out through.For single crystal copper,the influence mechanism of cutting edge radius,crystal orientation and cutting speed on the cutting process of crystalline copper curved surface is emphasized;for bicrystal copper,the influence mechanism of grain boundary on the process is addressed.The influence mechanism of cutting edge radius,cutting speed and misorientation angle of adjacent grains on the machining of bi-crystal copper curved surface is comprehensively studied.The effect of different machining parameters on the suppression of the grain boundary height difference and the overall roughness of the machined surface is focused on.Experimental research is carried out to study the influence of crystal orientation,feed rate and cutting depth on the surface quality of single crystal copper curved surface under diamond cutting,which is also compared with simulation results.