• Transactions of the Society of Information Storage Systems
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• v.9 no.2
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• pp.32-35
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• 2013

Nowadays, function related to anti-vibration and anti-shock of storage devices is required because of portability. Therefore, many hard disk drive (HDD) studies about external shock and vibration have been performed. Especially, many studies are performed with non-operational shock. Most studies have used the fixed condition between spindle system and base when they wanted to analyze dynamic behavior of inner parts in simulation. But spindle system has actually stiffness and damping coefficient. Maybe difference of value would be happened between fixed condition and spring condition. So, we measured FRF of spindle system to know stiffness and damping coefficient in HDD. And we studied on dynamic behavior of inner parts by using calculated stiffness and damping coefficient. As a result, we confirmed the difference as boundary condition of spindle system.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.160-166
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• 1997

The spindle motor in a computer hard disk drive can be modeled as a rotor-bearing system supported by the base plate. Ball bearing is the crucial element to determine the stiffness of the spindle motor, and its design parameters and operating conditions determine the dynamic characteristics of the spindle motor. In the analysis of a rotor-bearing system with a short shaft like a spindle motor, the stiffness of the base plate as well as ball bearings must be considered accurately to analyze the dynamic charateristics of a spindle motor. In this paper, the lateral and the axial vibration of the spindle motor were analyzed by the transfer matrix method for the dual-shaft rotor-bearing model and by d.o.f lumped parameter model, respectively. The simulation results had good agreements with the experimental modal testing. The dynamic characteristics were fully investigated for the change of the major design parameters of the spindle motor, i.e. the preload of ball bearings and the rotational speed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1183-1192
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• 2000

This paper relates to the flexural vibration analysis of the hard disk drive (HDD) spindle systems by means of the finite element method. In contrast to previous researches, every system componebt is here analytically modeled taking into account its flexibility and also the centrifugal effect particularly for the disk. To prove the effectiveness and accuracy of the proposed method, commercial HDD spindle systems with two and three identical disks are chosen as examples. Then, their major flexural natural modes are computed employing only a small number of element meshes as the shaft rotaional speed is varied, and compared with the bumerical or experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1601-1608
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• 2000

This paper is concerned with the forced flexural vibration analysis of hard disk drive (HDD) spindle systems with multiple thin disks, supported by two ball bearings based on the finite element model. This is the extension of the previous work which analytically modeled every system component taking into account its structural flexibility and also the centrifugal stiffening effect especially for the disks. Among the end results, the forced time response is expectedly useful for the vibration control of the spindle itself or the position servo control of the magnetic head. On the other hand, the steady state responses such as the frequency response function and the unbalance response are useful for system identification. Futhermore, through a coordinate transformation the equations of motion is also derived with respect to the inertial frame for convenient analyses of certain classes.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.11-15
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• 1999

Monitoring of the cutting force signals in cutting process has been well emphasized in machine tool communities. Although the cutting force can be directly measured by a tool dynamometer, this method is not always feasible because of high cost and limitations in setup. In this paper an indirect cutting force monitoring system is developed so that the cutting force in turning process is estimated based on a AC spindle drive model. This monitoring system considers the cutting force as a disturbance input to the spindle drive and estimates the cutting force based on the inverse dynamic model. The inverse dynamic model represents the dynamic relation between the cutting force, the motor torque and the motor power. The proposed monitoring system is realized on a CNC lathe and its estimation performance is evaluated experimentally.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.37-39
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• 2007

This paper compared with field weakening operation methods for the spindle motor of machine tool in which high speed drive is required. The maximum torque field weakening algorithm ensures the full utilization of the output torque capability of the machine over 1/Wr method. From simulation, the validity of the Max_Te method is confirmed. It is verified that the Max-Te algorithm provided the improved torque capability over 1/Wr method. So, It is applicable to provide high performance control involving fast acceleration and precise speed control for the adjustable speed drive system of spindle.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.379-380
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• 2006

Recently, in spindle motors for hard disk drive (HDD) devices, fluid dynamic bearings (FDB) with herringbone grooves have come to be used instead of ball bearings due to the demand for high density recording of the devices etc. In this study, a 5-lobe bearing with high bearing stiffness using a sintered material was developed, and the bearing performance was examined by simulated calculations and experiments. As a result, it was clarified that the 5-lobe bearing had the required performance for practical use in the spindle motor for HDD

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.11a
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• pp.372-377
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• 2000

Recently, fluid bearing have been studied to apply to spindle motors for hard disk drive, printer and others. Since fluid bearing have excellent stiffness and good load carrying capacity, the bearing proved to be suitable for those devices related to computer industry. In this paper, the friction and wear characteristics of the bearing were studied. The bearing appears good performance at a high temperature and high wear resistance.

• 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.16 no.1 s.106
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• pp.12-18
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• 2006

This research investigates the electromechanical characteristics of a spindle motor in a free-falling mobile hard disk drive before unexpected shock. Electromechanical simulation includes a time-stepping finite element analysis of the magnetic field in a speed controlled brushless DC motor and dynamic analysis of the stationary and rotating part linked by the fluid dynamic bearing under the free-falling condition. Analysis results show that the dynamic characteristics of the rotating spindle system during free-falling state have an effect on the relative motion between the stationary and rotating part of HDD. It results from the variation of reaction force in the bearing area due to the gravity force exerted on the rotating part of HDD, and the free-falling condition can be detected by observing the signal of the spindle motor and disk-head interface without using an accelerometer.