The Research Of Mechanism Of Workpiece Material Surface Layer Formation During High Speed Machining

Component reliability is not only influenced by surface micro quality,but also by deep surface layer microstructure performance.Because parts of all external characteristics are determined by the surface layer microstructure,the organization decided to performance.So,it is very important to study the formation mechanism of the surface.In this paper,theoretical analysis,experiment research and finite element simulation are adopted to study the topic,the main contents and conclusions are as follows:(1)In this paper,single factor and orthogonal tests are adopted to design the experiments.Then measure surface roughness and analysis the relation between surface roughness and cutting parameters.The results show that feed rate,cutting speed and cutting depth has the most effect,a greater effect and the least effect on surface roughness,respectively among cutting parameters.With the feed rate and cutting depth increase,surface roughness increases linearly and gradually,with the cutting speed increases,surface roughness decreases slowly.(2)Theoretical calculation and experiment validation are taken for the formula,which can measure how difficult the adiabatic shear phenomenon happened.It proved that for the same kind of material,the more of cutting speed and the less of cutting depth,the stronger of adiabatic shear sensitivity.For different kinds of materials with the same cutting parameter,the greater of the material strength and the smaller of thermal diffusion coefficient,the stronger of adiabatic shear sensitivity.At the same time,relationship between adiabatic shear sensitivity and surface roughness is established.The stronger the adiabatic shear sensitivity,the smaller the surface roughness.(3)The surface layer microhardness survey shows that for different materials,the degree of strain hardening varies widely.Which speculates that the greater of material strength and the smaller of thermal conductivity,the larger degree of strain hardening.Different cutting speeds and cutting depths will cause surface work hardening rule changes.(4)Workpiece surface microstructure show that ? phase exists angle deflection inthe direction of the cutting speed,supposedly in the process of machining process,the tool flank surface has a large friction with the work surface.Cutting parameters have a little effects on surface microstructure morphology without tool wear.