Research On Nonlinear Dynamic Analysis And Vibration Control Of Boring Bar

Boring is one of the basic ways of cutting.The vibration during the boring process greatly limits the machining accuracy and production efficiency of the parts.As the connecting rod between the boring machine and the corresponding boring head,the boring bar is an important part of the cutting process.In the process of parts processing,the cutting force received by the boring cutter will be transmitted to the boring bar,thereby causing the vibration of the boring bar.The vibration of the boring bar not only affects the accuracy of the processed surface,but also reduces the service life of the tool.When the vibration is too large,it may even affect the safety of the operator and the service life of the machine tool.When the magnetorheological fluid is introduced into the boring bar system,the in-depth study on the vibration reduction of the boring bar system is carried out.The choice of the magnetorheological fluid damper model is crucial to the results.The application of fractional calculus theory in viscoelastic materials in recent years has laid the foundation for the establishment of a fractional order model of magnetorheological fluid dampers.The force-displacement curve and velocity-displacement curve of the fractional order Bingham model and the Bingham model of the magnetorheological fluid damper are analyzed,and the better hysteretic characteristics of the fractional order Bingham model under low frequency vibration are verified.When only considering the bending vibration of the boring bar and ignoring the axial vibration and torsional vibration.Establish a nonlinear dynamic model of the boring bar system.According to the type of boring bar and the position of the magnetorheological fluid damper added,the dynamic model of the single-degree-of-freedom and two-degree-of-freedom boring bar system is established.The main resonance response of the system is studied in depth,and the approximate analytical solution is obtained by the averaging method.By comparing the amplitude and frequency response curves of the numerical solution and the analytical solution,the accuracy of the approximate analytical solution is verified.Among them,when studying the two-degree-of-freedom vibration reduction boring bar system,the effects of the mass of the vibration reduction block and the equivalent rigidity of the dynamic vibration absorber on the system vibration were analyzed in detail.Since the magnetorheological fluid damper has the characteristics of continuous controllability,the magnetic field can be changed by controlling the magnitude of the current to change the damping force provided by the magnetorheological fluid damper.Therefore,this paper uses a semi-active control strategy to suppress vibration.Semi-active control is a parameter control.The current is adjusted by judging the motion state of the magnetorheological fluid damper,thereby changing the damping force provided by the magnetorheological fluid damper.Under the semi-active control strategy,the average method is used to solve the steady-state solution of the system,and the power series method is used for numerical verification.Different semi-active control strategies are adopted for different types of boring bars,and the effects of semi-active control and passive control are compared.