• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.175-178
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• 2007

This paper is presented for the design of the thrust yoke for the spindle motors. HDD spindle motors are rotated by fluid dynamic bearing which consists of the shaft and the sleeve with the groove to generate the pressure. Because the thrust and journal clearances between shaft and sleeve is too small, around 8um and 2.5um, respectively, it is very difficult to design the bearing to come up to the disks to read and write the data. By the way, it is also so hard to overcome the load of the disks with only the thrust bearing. So, the paper is proposed for the trust yoke to come up to the disks considering of the force of the thrust bearing. In this paper, we proposed the thrust yoke with an unique fluid dynamic bearing in comparison with the motors without thrust yoke. Experimental results show the performance of the thrust yoke of the spindle motors for an HDD.

• KSTLE International Journal
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• v.2 no.2
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• pp.93-102
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• 2001

Ball bearings have been widely used for the spindle motor bearing in various kinds of information storage devices. Recently many researchers have been trying to replace ball bearings with fluid film bearings because of their superior NRRO(non-repeatable runout) characteristics. In this study, a numerical analysis has been conducted for the complicate bearing system composed of herringbone groove journal bearing and spiral groove thrust bearing for the spindle motor of the information storage device. At first, spindle motor bearing is modeled as journal bearing part and thrust bearing part separately, and then observed various influences of geometric parameters. Previous studies had considered only the translational motion of the journal bearing. However, this study takes the additional 2-degree of freedom rotation into consideration to attempt to describe the real motion of the spindle bearing. As a result, rotational stiffness coefficients and rotational damping coefficients are obtained. In addition, a spindle bearing system made up of four bearings is modeled and interpreted at once and coefficients of dynamic characteristics of each bearing are obtained. Finally, an eigen analysis of bearing system is made with these results. Through this analysis, it is possible to estimate an unstable condition of the system for given geometric parameters and to propose a method which is able to avoid the unstable condition by a proper adjustment of geometric parameters.

• The KSFM Journal of Fluid Machinery
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• v.9 no.5 s.38
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• pp.7-13
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• 2006

In the present study, we develop an analysis module to be applicable to design of sliding thrust bearings. The pressure equation is solved by using the finite element method. Average lubricant temperature is obtained from using the energy balance method. The module developed has been applied to three types of thrust bearing, such as tapered-land thrust bearings of angular and diamond types, and tilting-pad thrust bearings. Effects of the dam of the tapered-lad thrust bearings have also been investigated. It has been seen that the tapered-land thrust bearings of angular type result in the highest load capacity, while the tilting pad thrust bearings result in the lowest lubricant temperature. It has also been seen that the dam in the tapered-land thrust bearings increases both the load capacity and lubricant temperature.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.235-242
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• 2000

In this paper, the dynamic characteristics of coupled herringbone groove journal bearings and spiral groove thrust bearings with conical motion were numerically analyzed, The bearing performance characteristics were calculated by the perturbation method and are solved by FDM. Stability of bearing was obtained from the threshold of instability.

• Tribology and Lubricants
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• v.23 no.3
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• pp.109-116
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• 2007

A scroll compressor is on the increase in the use for the cooling and ambition machinery because of the advantages about high efficiency, low vibration and low noise. The design of thrust bearing for scroll compressor has depended on the experience. The lubrication considering the squeeze flow was applied for high side shell and low side shell of scroll thrust bearing. This work was based on governing fluid lubrication equation at the general coordinate. It shows the behavior for an orbiting scroll with direct numerical analysis using FDM. This study obtained the theoretical design value by finding load capacity and tilting angle of an orbiting scroll for thrust bearing in a scroll compressor. Especially this work performed the analysis about the design parameter. The program was written using Visual C++ to enhance user to change the design parameter easily. In particular the result value and the pressure profile were displayed as windows in every step for user to understand without difficulty.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.136-145
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• 1999

This paper describes the surface roughness effect in parallel thrust bearing. In mixed lubrication, some contacts will take place between asperities, and partial lubrication will occur. An average Reynolds Equation is utilized to determine effects of surface roughness on partially lubricated contacts. By using an autocorrelation function for the surface profile, surface model is generated numerically Although the two surfaces are parallel in thrust bearing separated by thin film, the pressure peak is formed due to asperites. By means of surface profile parameters, it is shown that which surface is optimal for the parallel thrust bearing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.478-483
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• 2005

This paper presents the comparison analysis of a Journal and thrust FDB (fluid dynamic bearing) and a conical FDB in a HDD spindle motor. The Reynolds equation is appropriately transformed to describe journal, thrust and conical bearing. Finite element method is applied to analyze the FDB by satisfying the continuity of mass and pressure at the interface between the hearings. The pressure field of the bearings is numerically approximated by applying the Reynolds boundary condition. The load and friction torque are obtained by integrating the pressure and the velocity gradient along the fluid film. The flying height of the spindle motor is measured to verify the proposed analytical result. This research shows that the conical bearing generates bigger load capacity and less friction torque than the journal and thrust bearing in a HDD spindle motor.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.87-95
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• 2005

This paper proposes a method to calculate the characteristics of a coupled hydrodynamic journal and thrust bearing of a HDD spindle motor. The governing equations for the journal and thrust bearings are the two dimensional Reynolds equations in $\theta z$ and $ r\theta$ planes, respectively. Finite element method is appropriately applied to analyze the coupled journal and thrust bearing by satisfying the continuity of mass and pressure at the interface between the journal and thrust bearings. The pressure in a coupled bearing is calculated by applying the Reynolds boundary condition and compared with that by using the Half-Sommerfeld boundary condition. The static characteristics are obtained by integrating the pressure along the fluid film. The flying height of spindle motor is measured to verify the proposed analytical result. This research shows that the proposed method can describe HDB in a HDD system more accurately and realistically than the separate analysis of a journal or thrust bearing.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.1997-2007
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• 2002

Composite air spindles are appropriate for the high-speed and the high-precision machining as small hole drilling of printed circuit board (PCB) or wafer cutting for manufacturing semiconductors because of the low rotational inertia, the high damping ratio and the high fundamental natural frequency of composite shaft. The axial load and stiffness of composite air spindles fur drilling operation are determined by the thrust ben ring composed of the air supply part mounted on the housing and the rotating part mounted on the rotating shaft. At high-speed rotation, the rotating part of the thrust bearing should be designed considering the stresses induced by centrifugal force as well as the axial stiffness and the natural frequency of the rotating shaft to void the shaft from failure due to the centrifugal force and resonant vibration. In this work, the air supply part of the thrust bearing was designed considering the bending stiffness of the bearing and the applied load. The rotating part of the thrust bearing was designed through finite element analysis considering the cutting forces during manufacturing as well as the static and dynamic characteristics under both the axial and con trifugal forces during high-speed rotation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.846-852
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• 2004

This paper proposes a method to calculate the characteristics of a coupled hydrodynamic journal and thrust bearing of a HDD spindle motor. The governing equations for the journal and thrust bearings are the two dimensional Reynolds equations in ${\theta}z$ and $r\theta$ planes, respectively. Finite element method is appropriately applied to analyze the coupled journal and thrust bearing by satisfying the continuity of mass and pressure at the interface between the journal and thrust bearings. The pressure in a coupled bearing is calculated by applying the Reynolds boundary condition and compared with that by using the Half-Sommerfeld boundary condition. The static characteristics are obtained by integrating the pressure along the fluid film. The flying height of spindle motor is measured to verify the proposed analytical result. This research shows that the proposed method can describe HDB in a HDD system more accurately and realistically than the separate analysis of a journal or thrust bearing.