Analysis And Research On Machining Stability Of XK7132 Vertical CNC Milling Machine

In order to solve the problem of regenerative chatter which affects the machining stability of XK7132 vertical CNC milling machine,a dynamic model of two-degree-of-freedom milling system considering regenerative effect is established based on regenerative chatter theory and modern control theory.On the basis of the dynamic cutting thickness theory,the dynamic milling force is modeled and simulated,and the milling force coefficients of the workpiece material are obtained by means of average milling force model and linear regression analysis,which lays a foundation for predicting the chatter stability domain.According to the analytical method and the semi-discretization method,the simulation algorithms are compiled,and the stability lobe diagrams(SLD)are drawn successfully.The influence trends of the processing conditions on the chatter stability domain are summarized.In addition,an attempt was made to construct a three-dimensional lobe diagram.Aiming at the dynamic characteristics such as regeneration effect,cut-in effect and falling effect,which significantly affect the cutting chatter,the 2D and 3D dynamic simulation of the milling process are carried out by using the finite element analysis software ABAQUS.The relationship between milling force and chip formation and the effect of some parameters on dynamic milling force are analyzed emphatically,which provides guidance for optimizing process parameters and improving milling stability.The finite element analysis software ANSYS is used to conduct the numerical modal analysis of end milling cutter with different overhang lengths and diameters.The variation of natural frequencies and mode shapes of the tools under different modes are mainly studied,which provides a reference for avoiding chatter caused by cutting resonance and mode coupling.The modal test is designed and accomplished,and the frequency response function curve of XK7132 vertical CNC milling machine tool system is obtained.Then the modal parameters such as natural frequency,modal stiffness and damping ratio are identified,and the real parameter lobe diagram of the milling machine is constructed accordingly.Finally,the chatter stability domain verification test is carried out.With the axial cutting depth is gradually increased at a specific spindle speed,the stable limit axial cutting depth is obtained,which is basically consistent with the simulation and confirms the accuracy and reliability of the prediction.Based on the above research,a dynamic simulation system is developed,and the programs are modularized and visualized,which is convenient for scientific research and engineering use.The work of this paper provides a reliable theoretical basis for the machine tool to avoid chatter hazards,improve machining quality,efficiency and stability in actual production.At the same time,it has a general guiding significance for improving the level of CNC milling technology.