Nonlinear Dynamics Analysis In Turning Process

Machine tool machining is an important part of modern industrial production,and turning chatter is a common destructive phenomenon in the process of machine tool turning machining,and the occurrence of chatter can seriously reduce the turning efficiency.Therefore,this paper takes the nonlinear factors in the turning process as the research object,and uses a combination of dynamics modeling and numerical simulation to analyze the influence of nonlinear factors on the dynamic response characteristics of the system during the chattering process.Firstly,the current state of domestic and foreign research on the nonlinear dynamics of turning chatter is analyzed,its nonlinear factors are described,the concept of possible chaotic bifurcation and the theory of numerical simulation are summarized,the theoretical analysis of forced regenerative chatter is carried out,and the main research content of this paper is clarified.Secondly,the machine tool and the workpiece are flexibly combined as a whole,and the chattering model is simplified to a single-degree-of-freedom forced chattering system.The effect of amplitude and frequency on the dynamic response characteristics of the system is analyzed by using Matlab numerical simulation and bifurcation diagrams and local analysis diagrams at different amplitudes and frequencies,and it is found that under certain conditions,the system states corresponding to different parameters are selected differently,and the main way to the chaotic path of the single-degree-of-freedom turning system is accomplished by multiplication,inverse multiplication and mutation,and the energy of the periodic motion is concentrated in the periodic The energy of the periodic motion is concentrated in the periodic state while the energy of the non-periodic motion is uniformly and chaotically distributed,and the effect of frequency on the system is found to be greater than that of amplitude.The effect of different amplitudes on the stability of the system is compared and analyzed,and it is found that the reduction of the amplitude is beneficial to improve the stability of the system under certain conditions.Considering that the workpiece also has nonlinear factors,a two-degree-of-freedom forced chattering system dynamics model is established,and based on the basic principles of Newton’s law of motion and Hooke’s law to describe the system motion,the two-degree-of-freedom differential equations are listed,and the effect of the turning width on the stability of the system is analyzed.Using the amplitude and turning width as the bifurcation parameters,it is found that the two-degree-of-freedom forced chattering system has more complex dynamic response characteristics,and various forms of motion such as Hopf bifurcation,multiplication bifurcation,annular multiplication bifurcation and abrupt change occur during the transition between periodic and non-periodic motion.By keeping the other parameters constant and changing only the turning width,it is found that an appropriate reduction of the turning width is beneficial to reduce the vibration amplitude and increase the stability of the tool operation,but it does not necessarily make the system exit from the proposed periodic and chaotic motion.Finally,a three-degree-of-freedom turning system model is established by considering a more comprehensive turning whole consisting of machine tool,tool and workpiece.Numerical simulations reveal that its path to chaos occurs in the form of Hopf bifurcation and abrupt change of motion.For different damping ratios of the system,it is found that a larger damping ratio is beneficial to improve the stability of the system,but does not necessarily free the system from non-periodic motion.In this paper,the effect of system parameters on the turning system is studied by analyzing the dynamical behavior of the turning forced chattering system model,which provides a theoretical basis for improving the stability of the turning system.