Dynamic Modeling And Stability Analysis In Milling Machining Process

Milling possessing with high efficiency,high precision and low cost has been widely utilized in key industries such as aerospace,shipping,die and mold,and automotive.Chatter in the milling process often occurs,which seriously affects the quality and efficiency of machining,shortens the tool life,and even causes part damage and equipment damage.Hence,it is of great significance to analyze the milling stability,predict and expand the milling stability region for suppressing chatter,ensuring the milling safety and improving the milling efficiency.In this paper,from the viewpoint of machining dynamics model,a precise integration-based thirdorder full-discretization method(PI-3rd FDM)is proposed to predict the milling stability with high efficiency and accuracy.The combined method for prediction of milling stability and surface location error is presented to reveal the influence of process damping and mode coupling on milling stability and surface location error.The active-and passive-suppression method is proposed.The influence of tool geometry parameters and spindle speed on milling stability is revealed,and the software for predicting the dynamic behavior of milling process is developed to study the application of milling dynamics and the active-and passive-suppression technology.The main research content are as follows:The PI-3rd FDM is proposed to predict the milling stability with high efficiency and accuracy via the direct integration scheme.The involved state term and time delay term is approximated by third-order Newton and Hermite interpolation polynomials,respectively.The exponential matrix is calculated with the precise integration method without the inverse matrix calculation,which obviously improves the numerical accuracy and computational efficiency of the traditional stability prediction method.At the same time,the method is extended to predict the variable speed and variable pitch milling stability.A 2-DOF milling dynamic model considering regenerative effect,process damping and mode coupling effect is proposed.The combined method for prediction of milling stability and surface location error is proposed.Based on this,the influence of process damping and mode coupling on milling stability and surface location error is revealed,and the proposed model has been verified with milling tests.The theoretical and experimental results both demonstrate that the process damping and mode coupling effect of the tool cannot be neglected for accurate and reliable prediction of the milling stability and surface location error.A helix angle-based 2-DOF milling model considering cutter pitch and spindle speed variation is developed.The active-and passive-chatter suppression method in milling process is proposed.The proposed model and method are verified with time domain simulations.Moreover,the numerical simulation is utilized to examine the effect of helix angle,variable pitch cutter and variable spindle speed on the milling stability boundaries.The dynamic behavior prediction system for milling process is developed successfully based on MATLAB platform,which can offer the simulations of cutting force,the prediction of dynamic machining error,the prediction of milling stability and time domain simulations.The interface is simple and friendly,which improves the simulation efficiency,and provides theoretical guidance for the technologist or the front-line worker to select chatter-free milling parameters.