Dynamics And Machined Surface Topography Of High Strength And Toughness Mold Steel In Peripheral Milling

Chatter and tool deformation in milling process were the main reasons for the reduction of product surface quality and production efficiency.In this thesis,for the peripheral milling process of high strength and toughness mold steel,taking some influential factors such as tool deformation and chatter into consideration,the cutting force,the cutting stability and the formation mechanism of the three-dimensional topography of the machined surface were analyzed by the combination of analytical modeling,simulation and experimental research.Based on the analysis of the interaction mechanism between tool deformation and instantaneous cutting thickness and the cutting path of the cutting edge,the instantaneous cutting thickness model considering the instantaneous deformation of the tool during peripheral milling and the residual height of the previous tooth cutting under the real tooth trajectory was proposed.Based on the traditional instantaneous cutting force algorithm,a nested iterative convergence algorithm of cutting force was derived.According to the above analytical model,the simulation calculation of peripheral milling force was carried out,and the correctness of the model and simulation was verified by experiments,and the prediction of instantaneous cutting force in peripheral milling was realized.The dynamic force model and the dynamic model considering the helical angle effect of cutting tool were established,which were expressed by the time delay differential equation with periodic directional coefficient.The dynamic characteristics of the machining system were obtained by experimental modal analysis,and the dynamic model was solved by full-discretization method.The chatter stability lobes was obtained by simulation and verified by cutting experiments,which provides a theoretical basis for the chatter suppression by optimizing machining parameters.The surface topography of the peripheral milling of mold steel was studied and analyzed by the combination of analytical modeling and experiment.The dynamic model was solved by numerical method in time domain,and the effect of forced vibration on displacement of tool center point was obtained.Taking tool eccentricity,deformation and forced vibration into consideration,the relative motion trajectory equation of the cutting edge and the workpiece in peripheral milling was established.The prediction model of three-dimensional surface topography considering cutting tool parameters,processing parameters and error factors was established.The orthogonal experiment of mold steel peripheral milling was designed.The response and sensitivity relationship between the characterization parameters of machined surface topography and cutting parameters were obtained by using statistical methods.Based on the prediction model,the influence of tool parameters on surface topography was analyzed,and the influence rule and control mechanism of cutting parameters and tool parameters on surface topography characteristics were clarified,providing a theoretical guidance for parameters optimization direction and interval.