Research On Structural Design And Vibration Control Of Magnetorheological Vibration Damping Boring Bar

Boring bar are widely used for deep hole machining,and the increased length of the bar can lead to a reduction in its own stability,and during machining the bar enters the workpiece and the working conditions are closed to allow direct observation of the bar in real time.Boring bar vibration is complicated by the effects of cutting heat and cutting forces,which can have an impact on the surface roughness of the workpiece.In this paper,a magnetorheological fluid vibration damping boring bar is designed to ensure the stability of the boring process,and a system platform is established to monitor the machining status of the bar in real time.Firstly,the self-excited vibration during the boring process is described and the factors influencing the damping are analyzed.The basic characteristics and mechanical models of magnetorheological fluid are then introduced,and the working conditions and mechanical models of magnetorheological fluid are selected to meet the requirements of this study,providing the basis for the structural design and theoretical analysis of the vibration damping boring bar.Secondly,the structure of the magnetorheological fluid vibration damping boring bar is designed,and a dynamics model is established based on the vibration damping boring bar to analyze the effect of different basic parameters on the vibration damping effect of the vibration damping boring bar;the damping analysis of the magnetorheological fluid absorber inside the vibration damping boring bar is carried out to obtain the effect of different magnetic field strength on the damping of the magnetorheological fluid absorber;from the direction of optimizing the magnetorheological fluid absorber structure,the change of current in the magnetorheological fluid absorber is analyzed The effect of changes in current in the magnetorheological fluid absorber on the magnetic field strength of key components is analyzed to optimize the structure of the magnetorheological fluid absorber and improve the damping effect on the vibration damping boring bar.A monitoring system and control system is then built for the vibration damping boring bar.The main functions of the monitoring and control system are defined: the monitoring system collects the displacement,velocity and acceleration signals from the tip of the boring bar,and through the designed data analysis module,obtains the excitation frequency of the vibration damping boring bar.The control system regulates the damping of the damping bar.Afterwards,the hardware suitable for the monitoring and control system is selected and its parameters are presented.The overall architecture of the monitoring and control system is proposed,and the monitoring and control system is designed based on the LABVIEW software platform.Finally,the vibration control of the magnetorheological fluid vibration damping boring bar is experimentally verified.Firstly,the magnetic field of the conductor is measured by a magnetic field measuring instrument,which shows that the magnetic field strength increases as the current increases,and the overall error is less than 15%compared with the simulation in Chapter 3;the basic parameters of the boring bar and the magnetorheological fluid absorber can be obtained by testing the dynamic parameters of the vibration damping boring bar,and the amplitude multiplier surface under the current vibration damping boring bar basic parameters is plotted;the magnetorheological fluid absorber is tested,which proves the good vibration damping effect of the magnetorheological fluid absorber.Secondly,the experimental conditions of the vibration damping boring bar were carried out,and the performance of the bar was analyzed by different boring parameters,using vibration acceleration and surface roughness as evaluation indexes,and the results showed that the maximum decrease in vibration acceleration of the bar was 38.7% and the maximum decrease in surface roughness was 42.2%.The feasibility of the vibration damping effect of the magnetorheological fluid vibration damping boring bar was verified.