Influence Of Instantaneous Contact Stiffness On Friction And Wear Of Milling Cutter Flank And Its Prediction

High efficiency milling is a sophisticated technology used in the manufacture of heavy machinery parts and key aircraft components.Instantaneous contact stiffness is an important parameter in nonlinear dynamic analysis of milling process,which directly affects the formation process of workpiece machining transition surface,and then leads to the difference of wear degree at different positions of flank.Controlling the wear of the flank of milling cutter,and improving the life of cutter teeth are important means to realize the cutting of high feed milling cutter.Under the project ’Multi-scale coupling mechanism of nonlinear friction dynamics and wear of high efficiency milling cutter(51875145)’,and the key project of Heilongjiang Natural Science Foundation ’Orderly multi-source flow evolution mechanism and key technology of high energy efficiency milling heavy machine tool basic components(ZD2020E008)’,the influence of instantaneous contact stiffness of tool-workpiece friction pair interface on friction force,friction coefficient and wear strength under cyclic cutting load was studied.Combined cutting experiment,the characteristics identification and prediction of instantaneous contact stiffness on friction and wear of flank under vibration were studied.Combined with the influence of cutting vibration,instantaneous contact state between tool and workpiece,surface morphology and other factors on the instantaneous contact stiffness of the flank,revealed the instantaneous deformation and wear area of flank during cutting,and the instantaneous deformation of the flank under external load is analyzed.According to Hertz theory,an equivalent contact model between the flank and the processing transition surface.Using fractal geometry theory,the roughness model of flank,and the influencing factors of the instantaneous contact stiffness of the asperity were studied.According to the theory of contact mechanics,the change of instantaneous contact stiffness of flank under different deformation conditions was analyzed.Provides a basis for studying the evolution of instantaneous contact stiffness of flank under vibration.The tool tooth wear area was selected based on the experimental results,and the feature points on the flank were selected to quantitatively analyze the stiffness at specific position.To describe the instantaneous contact state of the milling cutter when machining the workpiece.Infinitesimal method was used to describe the distribution state of instantaneous contact stiffness of the flank,and the distribution characteristics of the instantaneous contact stiffness during the cutting process were analyzed.The variation curve of instantaneous contact stiffness between flank and workpiece transition surface with the rotation angle of cutter tooth in the same period was solved,and the evolution characteristics of instantaneous contact stiffness of flank under vibration were studied.In order to study the influence of the instantaneous contact stiffness of the toolworkpiece friction pair interface on the friction force and friction coefficient under cyclic cutting load,the instantaneous friction coefficient and friction force were solved.The curve of friction force and friction coefficient with rotation angle was solved,and the instantaneous friction force and friction coefficient of flank under vibration were studied.The distribution state of instantaneous wear increment of flank was characterized,and the influence of rotation angle of cutter tooth on cutter tooth wear was studied.The change of the cumulative wear depth of the flank during the whole cutting process was characterized,and the cumulative wear evolution process of the flank was studied.Taking the instantaneous contact stiffness as the independent variable,the friction force and the wear increment as the dependent variable,the corresponding curves of the friction force and the wear increment with the instantaneous contact stiffness were drawn,and the influence of the instantaneous contact stiffness of the flank on the friction and wear under vibration was studied.Existing tool wear prediction models ignore the coupling effect of external force and internal force,and propose a positionable prediction tool flank wear model based on the instantaneous contact stiffness of the flank.To establish a tool surface wear prediction model,based on BP neural network.Taking the instantaneous contact stiffness,the coordinates of the feature points of the flank coordinate system,the instantaneous rotation angle and the vibration displacement as inputs,and the instantaneous wear increment was taken as the output.The training and verification of the wear prediction of the flank of the BP neural network.The accuracy of the instantaneous contact stiffness model and the simulation results of flank were verified.Finally,the morphology of the tool surface wear area were detected,and the calculation model of contact stiffness and the simulation results of tooth surface wear were verified.