Surface Topography Characteristics And Influencing Factors Analysis And Prediction Of Ball-end Milling Hardened Steel

With the continuous expansion of manufacturing demand,high-speed milling with ball-end milling cutter has become one of the main processing methods for automotive mold cover parts,the surface quality after processing has significant influence on the working performance of the mold.Affected by processing parameters,tool size,the surface after processing will form pit-like topography with regular arrangement of textures,and the fluctuation of the milling force during the machining process inevitably causes tool vibration,different milling parameters,tool vibration and other factors comprehensively affect the formation of surface topography.Conventional research methods are mostly to establish empirical formulas for milling parameters and workpiece surface quality,while ignoring the inherent influence mechanism between them.This paper through the forming mechanism of the surface topography,establish surface topography prediction model considering the influence of milling parameters and tool vibration,the surface topography of hardened steel Cr12Mo V in high-speed milling of the ball-end milling cutter is analyzed by the combination of experiment and simulation,Obtain tool vibration parameters,explore the influence of tool vibration and machining parameters on surface topography,and analyze the change law of milling force in the milling process including vibration,verify the accuracy of the simulation model by experiment,and established a prediction model of roughness and milling force.The specific research includes the following parts:Firstly,the forming mechanism of the surface topography of the workpiece during the milling process are analyzed,the two-dimensional geometric profile of the machined surface under different vibration amplitudes is studied;By building coordinate systems of the tool,machine tool,and workpiece,combined with the tool vibration matrix,the movement trajectory of the discrete points of the cutting edge in the tool milling process is obtained;Discrete the cutting edge and time of the ball-end milling cutter by Z-map method,and mesh the workpiece,using MATLAB software and the established cutting edge motion trajectory to program the machined surface topography simulation model,the established simulation model of surface topography under tool vibration gives theoretical basis for the research of different machining parameters and tool vibration on the change laws of surface topography.Secondly,through the design of single factor milling Cr12Mo V experiment,obtain the surface topography under the influence of different processing parameters,the microcosmic surface topography of the workpiece are observed through super deep scene 3D microscope and white light interferometer,explain the reason for the dislocation of the surface texture between adjacent toolpaths;Through the established simulation model and experimental results,analyze the change of surface topography with the processing parameters without the influence of vibration,and conduct in-depth analysis of the causes;The change of surface topography caused by the vibration is observed by the white light interferometer,substitute the measured amplitude and frequency parameters into the surface topography simulation model,compare with the processed surface topography obtained from the experiment;Taking the three-dimensional surface roughness as the evaluation index,the error analysis of the milling profile simulation model and the experimental data is carried out.Then,three-dimensional finite element milling simulation model is established for the milling process through ABAQUS software.By setting the amplitude,the stress and strain of the workpiece under different amplitudes and the change of milling force are studied;The orthogonal test table combined with the analysis of variance method was designed to study the influence of different parameters on the milling force.Finally,through LSSVM,the prediction model of the maximum height S_z,the three-dimensional arithmetic average height S_a and the milling force F is established.Using improved PSO to search for the optimal solution of the kernel width coefficient and regularization parameter in LSSVM,program the prediction model of improved PSO-LSSVM.The results show that the proposed prediction model can offer basis for the selection of experimental parameters of actual milling processing.