Research On Characteristic And Performance Of Cutting Surface In Machining Hardened Steel

Hardened steel is a typically difficult-to-machine material,it is widely used in high-level equipment due to its high mechanical strength and physical property.However,the surface features,e.g.hardened steel cutting surface topography,white layer and residual stress distribution,affect the precision,wear resistance,fatigue strength and life of the parts.Therefore,it is very neces Sary for spread the hardened steel cutting technology to study the generation mechanism and performance of machining surface.The variation regulation of the surface characteristics of hard cutting machining is explored,as well as the relationship between surface characteristics and fatigue life is explored taking hardened steel machining surface characteristics as the research object.Presents the impact rules of cutting parameters and tool wear on the surface characteristics e.g.the residual stress,the white layer and the surface morphology.Also the influence of the surface characteristics to the fatigue life is analyzed.Models of predict and evaluation are established for the characteristics of the cutting surface.Firstly,the experiment is carried out for characteristics of the hard cutting surface,where scanning electron microscopy,X-ray diffraction(XRD),confocal microscope,super depth of field microscopy and other detection equipment are applied to detect surface micro-machining characteristics.The thesis also presents surface layer generation mechanism and the influence of cutting parameters on the surface features.The results demonstrate that feed has the greatest influence on the surface morphology,and the white layer and the residual stress are sensitive with the tool flank wear.Secondly,hard cutting fatigue performance test is carried out,and the fatigue property of Samples are observed.The influence regulation of machining surface characteristics on the fatigue property is obtained,under the condition of different cutting parameters and tool wear.Thesis proposes the influence of thedamage morphology and surface characteristics of fatigue specimen on the fatigue property.Finally,based on the data obtained from cutting experiments of hardened steel,the model of surface characteristics is established to predict the surface characteristics under the condition of different cutting parameters and tool wear according to BP neural network.Combing with the results of fatigue performance test,by using the method of fuzzy comprehensive evaluation,the model is established to evaluate the surface characteristics.