【作者】 李洪来；

【导师】 林树忠；

【作者基本信息】 河北工业大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 高速的微小型旋转机械(如硬盘驱动器)对动态性能有非常高的要求。螺旋槽动压滑动轴承由于具有出色的动力学特性,得到广泛的应用。本论文以高速硬盘微小型滑动轴承—主轴系统变温条件下的稳定性为主要研究目标,首先对耦合径向和推力轴承的刚度和阻尼系数进行了分析计算,将径向和推力轴承的雷诺方程及其扰动方程转化为有限元方程,不仅考虑径向和推力轴承之间交界处压力和流量的连续性,还包括雷诺边界条件的数值分析以及空穴现象的模拟。分析表明:此方法可以高效稳定的计算耦合径向和推力轴承的动态特性系数。径向和推力轴承的耦合效应的研究还表明,此方法可以计算出径向推力轴承径向与轴向上交叉耦合动态特性系数。之后,在小偏心距条件下,推导出硬盘主轴系统稳定性判据以确定系统的临界转速和临界质量。通过求解硬盘主轴系统动压滑动轴承的雷诺方程以及系统的五自由度运动方程研究其动态特性。首先,应用有限元法求解雷诺方程确定油膜压力分布,得出油压分布规律;对油膜压力和剪切应力积分得支承力和摩擦力矩,然后使用Runge-Kutta法求解系统的非线性运动方程,确定了硬盘主轴的涡动及偏摆等动态特性。随着工作温度的升高,润滑油的粘度和轴承间隙显著减小。本文应用非线性膨胀理论精确计算轴承间隙,修正了热流体动力润滑模型。环境温度确定后计算相应的润滑油的粘度和轴承间隙,然后求解变温条件下的雷诺方程可得硬盘驱动器主轴轴承的静态和动态特性参数,得出主轴系统静、动态特性随温度变化的规律。结果表明,环境温度的变化是影响硬盘驱动器主轴轴承动态特性的重要因素。更多还原

【Abstract】 A micro-rotating machinery such as hard disk drive (HDD) requires high efficiency and robust dynamics in high operating speed. Small-sized herringbone grooved journal bearings (HGJBs) are widely used for this application thanks to their excellent dynamic characteristics.The analysis herein on small-sized herringbone grooved journal bearings in hard disk drive is expected to distill design guidelines with main goals of reaching larger stability margin. To fulfill the aforementioned goal, the present study starts with proposing a method to calculate the stiffness and the damping coefficients of the coupled journal and thrust bearings. Reynolds equations and their perturbation equations of journal and thrust bearings 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 cavitations phenomenon. The stiffness and damping coefficients of the proposed mathematical method are compared with those of the numerical differentiation of the bearing force with respect to finite displacements and finite velocities of bearing center. It shows that the proposed method can calculate the dynamic coefficients of a coupled journal and thrust bearing more numerically stable and computationally efficient than the differentiation method. It also investigates the coupling effect of the coupled journal and thrust bearing and it shows that the proposed method makes it possible to calculate the cross-coupled dynamic coefficients in the radial-axial direction of the coupled journal and thrust bearing. After the linearized stiffness and damping coefficients are evaluated, The threshold speed parameter and whirl frequency ratio are computed using the linearized stability analysis.This paper investigates the dynamic behavior of a HDD spindle system with fluid dynamic bearings (FDBs) by solving the Reynolds equation and the equations of a motion of a HDD spindle system in five degrees of freedom. FEM is used to solve the Reynolds equation in order to calculate the pressure distribution in fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors of a HDD spindle system, such as the whirling and the tilting motion, are determined by solving its nonlinear equations of motion with the Runge-Kutta method. Finally, this paper presents a method to investigate the characteristics of hydrodynamic bearings of a HDD spindle motor considering the variation of the clearance as well as the lubricant viscosity due to elevated temperature. This research shows that elevated temperature changes the clearance as well as the lubricant viscosity of the hydrodynamic bearings of a HDD spindle motor. In this article, the thermal expansion of the sleeve’s inner radius was determined by Luo Zai’s method. Once the viscosity and clearance of hydrodynamic bearings of a HDD spindle motor are determined, finite element analysis of the Reynolds equation is performed to investigate the static and dynamic characteristics of hydrodynamic bearings of a HDD spindle motor at elevated temperature. It shows that elevated temperature is an important design consideration which affects the dynamic characteristics of the hydrodynamic bearing of a HDD spindle motor.更多还原