| The motorized spindle is the core component of high speed precision machining,such as high speed machine tool and high speed machining center.Its running state is closely related to the processing ability and dynamic performance.Bearings,spindles and motor rotors in the motorized spindle are the main rotary components.The dynamic performance of the bearing-rotor system determines the performance of the motorized spindle.The establishment of the system dynamics model,the study of the influence of high speed on the dynamic performance,and the explanation of the energy distribution law of the system combined with the power flow theory are helpful to guide and promote the design and optimization of the motorized spindle,and improve the level of the motorized spindle industry in China.In this paper,a domestic type of C01 motorized spindle is taken as the research object.Combined with the quasi-static theory of angular contact ball bearing and the finite element modeling method of rotor dynamics,the dynamic model of bearing-rotor system of motorized spindle is established.Through the combination of theoretical modeling,numerical simulation and vibration experiment,the performance of angular contact ball bearing,the dynamic performance and energy distribution law of motorized spindle bearing-rotor system under high speed are studied.Specific research work is as follows :First of all,the structural characteristics of the motorized spindle and the setting of the spindle bearing are analyzed.The bearing-rotor system is determined as the research object.The bearing analysis model is established through the quasi-static theory of angular contact ball bearing,and the dynamic model of the motorized spindle bearingrotor system is established combined with the Timoshenko beam theory,which provides a theoretical basis for the later simulation analysis.Then,based on the three-dimensional model of C01 motorized spindle,the node is divided and defined.The simulation program is written by Mat Lab software,and the influence of rotational speed on contact angle,radial and axial stiffness of inner and outer rings of angular contact ball bearings is analyzed by numerical simulation.Based on the bearing simulation,the natural frequency and vibration mode of the bearing-rotor system are simulated,and the influence of bearing stiffness on the natural frequency of the system is analyzed.The vibration test platform of C01 motorized spindle is built in the laboratory,and the vibration test experiment of motorized spindle is designed and completed to verify the correctness of theoretical analysis.Finally,the harmonic response analysis of the motorized spindle bearing-rotor system is carried out to further analyze the dynamic performance of the system,and the response of the bearing support is mainly analyzed.In order to realize the application of power flow theory in motorized spindle,combined with the characteristics of Timoshenko beam element,the power flow is divided into bending power flow and shear power flow,and the corresponding calculation formula is deduced.The power flow distribution of motorized spindle bearing-rotor system is calculated by using the harmonic response analysis results,and the energy distribution of bearing-rotor system is obtained.Different bearing stiffness values are set to simulate the power flow of bearing-rotor system,and the influence of bearing stiffness on the power flow response of bearing-rotor system is obtained. |
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