Unbalance Dynamics Modeling And Vibration Feature Identification Of Motorized Spindle Affected By Eccentricity

High-grade CNC machine tool is the main equipment for manufacturing of key parts and components.It is an indispensable equipment in modern precision machining and also an indispensable part of national industry.As the core power output component of CNC machine tool,the vibration of motorized spindle during operation will seriously affect the machining quality and machining accuracy of parts of CNC machine tool.Motorized spindle in processing and manufacturing process due to the density distribution of the rotor material,can guarantee the quality of absolute symmetric distribution caused by the eccentric mass,the installation may cause errors in the centroid of the stator and rotor misalignment produce static eccentricity,these factors will make an imbalance motorized spindle vibration,exacerbated the vibration of the motorized spindle decrease stability.In order to analyze the dynamic behavior of unbalanced fault of motorized spindle caused by eccentricity and improve the operation stability of motorized spindle,this paper takes the eccentric motorized spindle developed by the research group as the research object and conducts the following research:(1)The background and significance of the research on dynamic modeling and vibration feature identification of motorized spindle affected by eccentricity are described,and the current research status of dynamic modeling of motorized spindle faults and the research status of vibration feature identification methods of motorized spindle are analyzed.(2)The effects of mass eccentricity,static eccentricity,gyro moment,bearing contact force and preload force were considered,and the dynamic model was established by using Lagrange equation.The effects of relative eccentricity on unbalance magnetic tension,speed on vibration,mass eccentricity on vibration and static eccentricity on vibration are studied.It is found that the influence of static eccentricity on the axle path decreases with the increase of rotational speed.Analysis in time domain and frequency domain shows that the frequency of fundamental frequency vibration will increase and the peak value will increase with the increase of rotational speed.(3)An improved all-phase fast Fourier transform method is proposed to identify the characteristics of unbalanced vibration signals of motorized spindle.The vibration signal calculated by the dynamic model is used for signal processing.Through the comparison with Fourier transform method,mutual power method,cross correlation method processing results.The results show that the improved all-phase fast Fourier transform method has high accuracy in the identification of amplitude and phase,and has advantages over the other three methods in the identification of fault features of eccentric motorized spindle.(4)By building an eccentric motorized spindle test platform,the vibration test of motorized spindle under different eccentricity conditions is carried out.The experimental results show that the greater the eccentricity,the greater the unbalance vibration of motorized spindle.Through the spectrum analysis,it is found that there is also a large amplitude at 0Hz.The experimental results are close to the simulation results in a certain range,which indicates that the model is more accurate and can simulate the motorized spindle in the eccentric state to a certain extent.The improved all-phase fast Fourier transform method is used to identify the vibration characteristics under experimental conditions,and the identification results are taken as the input of dynamic balancing parameters.The dynamic balancing effect is remarkable,and the balancing accuracy is improved by 10.2% compared with the algorithm of the balancing machine.The research results lay a theoretical foundation for fault analysis and diagnosis of motorized spindle with coupling faults.