| Plunge milling is an efficient material removal method in milling process,which can significantly improve the production efficiency of complex parts so as to reduce the production costs and has been widely used in aerospace industries.Plunge milling mainly bears the axial force and can solve these problems such as the low efficiency and high cost in the process of hard-to-cut materials,complex surfaces,deep grooves and thin-walled parts.However there is a chattering problem in the plunge milling process when cutting parameters are unreasonable or the tool overhang is large,which maybe seriously affects the workpiece quality.Therefore,the main research contents are the cutting mechanism and stability of plunge milling:(1)The dynamic model of cutting width for the three types of plunge milling is established.And the correctness of the model is verified by MATLAB,which provides a theoretical basis for the dynamic milling force model and experimental research of the plunge milling.(2)The milling force model for plunge milling based on the force analysis of the plunge milling process is established.The cutting force of the micro-element is solved by discretizing the inserting cutter,and the milling force is obtained by superposition and coordinate transformation.The milling force coefficient of 30CrMnSiNi2 A is obtained by the average milling force method.Then the dynamic milling force coefficients model of the quadratic polynomial of cutting parameters is established.The milling force under different cutting parameters is solved by MATLAB,and the accuracy of the dynamic milling force coefficient model and the milling force model is verified by comparison with the experiments.(3)The modal test of the ultra-high-strength steel 30CrMnSiNi2 A is carried out,and the modal parameters of the plunge milling system are obtained by modal analysis.The three-degree-of-freedom dynamic model of plunge milling is solved by the full discretizationmethod,and the stability chart of the plunge milling process is obtained by MATLAB.The influence of the number of tooth,the stiffness,natural frequency,damping ratio of system and the milling force coefficient on the plunge milling stability chart is investigated by the control variable method.(4)In order to improve the cutting efficiency and ensure the stability of the plunge milling process,the cutting parameter optimization model of the plunge milling based on the milling force model and the stability chart is established.The optimization goal of this model is the maximum material removal rate,and the optimization parameters such as the cutting speed,feed rate,radial width and milling step is obtained.The research of this dissertation can realize the milling force prediction and stability chart prediction of ultra-high-strength steel 30CrMnSiNi2 A in the plunge milling,which has some significance for selecting of the best plunge milling parameters. |
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