Analysis of the influence of force and moment dynamic coefficients on lubricated thrust bearings

This paper proposes a method to calculate the stiffness and the damping coefficients of the coupled journal and thrust bearings considering tilting motion. The Reynolds equations and their perturbation equations are derived by linearization of bearing reaction with respect to the general five degrees of freedom, i.e. the tilting displacement and angular velocity as well as the translational displacement and velocity. Reynolds equations and their perturbation equations are transformed to the finite element equations by considering the continuity of pressure and flow at the interface between the journal and the thrust bearings. It also includes the Reynolds boundary condition in the numerical analysis to simulate the cavitation phenomena. The stiffness and the damping coefficients of the proposed method are compared with those of the numerical differentiation of the loads with respect to finite displacements and velocities of bearing center. It shows that the proposed method can calculate the dynamic coefficients of a coupled journal and thrust bearing more accurately and efficiently than the differentiation method.

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Calculation of Dynamic Coefficients in a Hydrodynamic Bearing Considering Five Degrees of Freedom for a General Rotor-Bearing System

Journal of Tribology ◽

10.1115/1.2834095 ◽

1999 ◽

Vol 121 (3) ◽

pp. 499-505 ◽

Cited By ~ 68

Author(s):

G. H. Jang ◽

Y. J. Kim

Keyword(s):

Degrees Of Freedom ◽

Disk Drive ◽

Spindle Motor ◽

Hydrodynamic Bearing ◽

Thrust Bearings ◽

Dynamic Coefficients ◽

Rotor Bearing ◽

The Moment ◽

Wedge Effect ◽

Bearing System

A complete method is presented to calculate the stiffness and the damping coefficients in a hydrodynamic bearing considering five degrees of freedom for a general rotor-bearing system. Perturbation equations are obtained from Reynolds equation by assuming the small amplitude motion of a bearing center, and are solved by the finite element method. Their characteristics due to eccentricity and misalignment are investigated for herringbone groove journal and thrust bearings in the spindle motor of a hard disk drive. This research shows that the dynamic coefficients increase with increasing the misalignment as well as the eccentricity due to the wedge effect. It also shows that the moment coefficients, which have been neglected in most of the previous analyses, are of significant magnitude in a journal bearing and have even bigger values for the thrust bearing when they are compared with the ball bearing in the same type of a spindle motor.

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Determination of the Dynamic Coefficients of the Coupled Journal and Thrust Bearings by the Perturbation Method

Transactions of the Korean Society for Noise and Vibration Engineering ◽

10.5050/ksnvn.2006.16.7.746 ◽

2006 ◽

Vol 16 (7) ◽

pp. 746-753

Keyword(s):

Perturbation Method ◽

Thrust Bearings ◽

Dynamic Coefficients

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Dynamic analysis of water-lubricated motorized spindle considering tilting effect of thrust bearing

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406216652437 ◽

2016 ◽

Vol 231 (20) ◽

pp. 3780-3790 ◽

Cited By ~ 7

Author(s):

Huihui Feng ◽

Shuyun Jiang

Keyword(s):

Reynolds Equation ◽

Thrust Bearing ◽

Dynamic Performance ◽

Large Diameter ◽

Machining Process ◽

Motorized Spindle ◽

Thrust Bearings ◽

Dynamic Coefficients ◽

Key Issues ◽

Dynamic Performances

The dynamic modeling for the rotor with large diameter thrust bearings is one of the key issues in the design and operation of water-lubricated motorized spindle. In the machining process, the spindle not only translates along the x, y, z directions, but also tilts about the x and y axes under the cutting forces. As a result, the tilting effect of the thrust bearing on the dynamic performances of the motorized spindle should be considered. A five degree-of-freedom dynamic model for the spindle is established based on the Newton’s Laws and the principle of Angular Momentum. The translational and tilting dynamic coefficients for both the journal and thrust water-lubricated bearings were obtained by using Reynolds equation. The computed results show that the tilting effect of the thrust bearing on the dynamic performance of the motorized spindle should be considered when a large diameter thrust bearing is employed.

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