Study on Rotor Dynamics Characteristics of High Speed Aerostatic Motorized Spindle during Fly-cutter Milling Process

doi:10.3901/JME.2021.13.045

Abstract

Abstract: In the actual machining process, cutting force, unbalanced magnetic pull and centrifugal force caused by unbalance distribution of rotor mass will cause rotor vibration, which will directly reduce the quality of the machined surface. In order to deeply analyze the problem, the rotor dynamic characteristics of aerostatic bearing motorized spindle in high-speed flying milling process are studied. A five degree of freedom rotor dynamic milling model is established considering the above forces. The calculation formula of unbalanced magnetic pull is given. The linear perturbation method of small whirl of rotor is assumed. The dynamic film thickness and the dynamic film force are substituted into the Reynolds equation, which is used to derive the formulas for calculating the translational stiffness, the damping and the angular stiffness and the angular damping of the bearing. The rotor dynamic equations are derived based on Newton Euler equation, which are solved by combining the state space model, characteristic equation, impedance method and initial condition of the system. The numerical program is compiled to simulate the dynamic characteristics of the rotor for empty cutting and interrupted cutting. It is found that the radial trajectory of the centroid is circular for empty cutting when the rotor reaches the stable operation state; during the cutting process, the vibration characteristics of the rotor are affected by the centrifugal force caused by the rotor mass eccentricity and the periodic cutting force.

Key words: fly-cutter milling, bearing-rotor system, dynamic characteristics, unbalanced magnetic pull

CLC Number:

TH133

LEI Qun, YUAN Yage, DU Jianjun, LI Liyi. Study on Rotor Dynamics Characteristics of High Speed Aerostatic Motorized Spindle during Fly-cutter Milling Process[J]. Journal of Mechanical Engineering, 2021, 57(13): 45-54.

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