Non-symmetrical three-lobe bearing spindle technology: a drive technology to increase aerial density

Yoshida, Shinobu; Kohno, Tohru; Saegusa, Shozo; Terayama, Takao; Yoshida, Takeshi; Hirai, Hiromu; Hamada, Yosuke; Yamaguchi, Takashi

doi:10.1109/20.492855

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…It is clearly seen from equation ( 14) that the piezoelectric compliance can be controlled by adjusting the shunt circuit admittance. By replacing the compliance term of the flexural stiffness D 11 of equation (7) with the shunted compliance, the flexural stiffness of the shunted piezoelectric bimorph can be obtained as…”

Section: Modeling Of the Shunted Drivementioning

confidence: 99%

“…To overcome this vibration problem, fluid dynamic bearings and squeeze air bearing dampers were frequently adopted [5][6][7], and shock analysis of the head-disk interface was undertaken in the suspension design process [8]. However, these research activities on the vibration suppression of HDDs were mainly concentrated upon dynamic characteristics analysis of the suspension or disk-spindle system only.…”

Section: Introductionmentioning

confidence: 99%

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Vibration control of an HDD disk-spindle system utilizing piezoelectric bimorph shunt damping: I. Dynamic analysis and modeling of the shunted drive

Lim¹,

Choi²

2007

Smart Mater. Struct.

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This work proposes a new piezoelectric shunt damping methodology to control the vibration of a computer hard disk drive (HDD) disk-spindle system. The first part of this work (part I) deals with dynamic modeling of the piezoelectric shunted drive, while the second part of this work (part II) covers experimental implementation of the proposed shunt circuits. In the modeling, a target vibration mode which significantly restricts the recording density increment of the drive is determined by analyzing the dynamic characteristics of the conventional drive. This is achieved by undertaking both modal testing and finite element (FE) analysis. In order to effectively suppress the unwanted vibration of the target mode, a piezoelectric bimorph is then designed and integrated to the drive by considering the mode shapes of the target vibration mode. The mechanical impedance of the shunted bimorph is derived from lamination theory and piezoelectric constitutive equations. In this derivation, the electromechanical coupling coefficient of the shunted drive is analytically incorporated with the mechanical impedance. Using the coupling coefficient, the shunt damping performance for the target vibration mode is predicted and evaluated by presenting the displacement transmissibility.

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Section: Modeling Of the Shunted Drivementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vibration control of an HDD disk-spindle system utilizing piezoelectric bimorph shunt damping: I. Dynamic analysis and modeling of the shunted drive

Lim¹,

Choi²

2007

Smart Mater. Struct.

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“…In order to satisfy such strict specifications, the spindle should be supported by a noncontact bearing system in both of the axial and radial directions, in place of conventional ball bearings, which inherently cause NRRO due to the geometrical imperfections of ball bearing elements (Takao, 1996). There have been numerous presentations about the noncontact bearing system for HDD spindle during the past few years, and most of such designs were about the bearing systems applying oil lubricated hydrodynamic bearings in both of the radial and axial supports (Roger Ku, 1996Ku, , 1997Swann and Talke, 1996;Zang and Hatch, 1995;Richter and Talke, 1998;Bouchard et al, 1987;Chen and Zhang, 1997;Yoshida, 1996;Futamota, 1996). The oil lubricated bearings have higher bearing stiffness than the gas lubricated bearings do.…”

Section: Introductionmentioning

confidence: 97%

Analysis and design of hydrodynamic journal air bearings for high performance HDD spindle

Ono

2003

Microsystem Technologies

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In this paper, we proposed the design concept of NRRO-free non-contact bearings for a high performance hard disk drive (HDD) spindle. We numerically analyzed three types of hydrodynamic journal air bearings [gas dynamic bearing (GDB)], such as a partial herringbone groove, a sinusoidal wave, and a taper-flat type. And we compared their performances in terms of pressure distribution, load capacity, radial stiffness, unbalance response, and stability threshold. For the design examples, we examined the Case 1 with 2.0 lm bearing clearance and 10000 rpm, and the Case 2 with 1.0 lm clearance and 15000 rpm. As a result of numerical analysis, we found that the taper-flat type was the most promising for high performance HDD spindle compared with the other types. It can have the bearing stiffness of about 3.0 · 10 6 N/m in Case 1 and of about 2.0 · 10 7 N/m in Case 2. We also discussed the allowance of parameters for the optimal design of the taper-flat type journal bearing. List of symbolsb g ðgÞ width of groove for groove type GDB [mm] b g ðtfÞ width of groove for taper-flat type GDB [mm] b f ðtfÞ width of flat part for taper-flat type GDB [mm] b t ðtfÞ width of taper part for taper-flat type GDB [mm] d g ðgÞ depth of groove for groove type GDB [mm] d g ðtfÞ depth of groove for taper-flat type GDB [mm] d r ðtfÞ depth of taper for taper-flat type GDB [mm] D diameter of GDB [mm] e quantity of static eccentricity of rotor [mm] K radial stiffness of GDB [N/m] K f tangential stiffness of GDB [N/m] L length of GDB [mm] m mass of rotor [kg] m 0 mass of unbalance [kg] " M M dimensionless stable mass NðgÞ number of grooves for groove type GDB NðtfÞ number of pairs for taper-flat type GDB P dimesionless hydrodynamic pressure P g dimensionless atmospheric pressure r 0 radial position of unbalanced mass [m] R radius of GDB [mm] W s ðwÞ amplitude of wave for wave type GDB [lm] W n ðwÞ number of wave for wave type GDB a position angle of static eccentricity of rotor [°] b g ðgÞ declined angle of groove for groove type GDB [°] l viscous coefficient [kg/ms] h circumfrential position angle of GDB [°] x external angular frequency [rpm] x 0 angular frequency of rotor [rpm] L bearing number W onset ratio (x/x 0 ) IntroductionRecently, HDD came to be a representative storage device by maintaining its remarkable market share in data storage devices, and it needs to have much higher recording density and performances. One of the core technologies for realizing higher performance in HDD may be the design and development of a high-speed spindle motor supported by a non-contact bearing system. When the area recording density is about 20 Gb/in 2 , the track density has to be about 50000 tracks per inch (TPI) at least, which means the requirement of under 0.03 lm of non-repeatable runout (NRRO) of a spindle. In order to satisfy such strict specifications, the spindle should be supported by a noncontact bearing system in both of the axial and radial directions, in place of conventional ball bearings, which inherently cause NRRO due to the geometric...

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“…A ball bearing is low in cost but has weak points in terms of non-repeatable run out, vibration, noise and poor durability to external shocks compared with a hydrodynamic bearing. Therefore hydrodynamic bearings such as spiral or herringbone groove type Hatch 1995, 1996;Ku 1996Ku , 1997, three-lobe type (Yoshida et al 1996) and others (Ono et al 1998;Zhu and Ono 1999) have been studied for application in hard disk drives. Since the reliability of lubricant sealing has been improved, a fluid bearing is now being widely used for hard disk drives not only in mobile computers but also in high-end computers.…”

Section: Introductionmentioning

confidence: 99%

Stability analysis of a disk-spindle supported by a plain journal bearing and pivot bearing

2005

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A hydrodynamic bearing is widely used for hard disk drives, and it is better than a ball bearing in terms of vibration suppression, noise reduction and shock resistance. However, its cost to performance ratio should be further improved. In this study we analyzed the stability of a disk-spindle assembly supported by a hydrodynamic plain journal bearing and a pivot bearing at the bottom of the shaft. As a result, we found that a half-frequency whirl of a vertical spindle caused by the plain journal bearing becomes stable if the gyro factor of the rotor is larger than 0.5. We examined the effects of the bearing design parameters on the stability of the diskspindle assembly, including the flexibility of the shaft. We also compared the stability of a disk-spindle assembly supported by two plain journal bearings and found that the vertical spindle is always unstable. Thus, the bottom end of the shaft should be supported as a fulcrum.

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Non-symmetrical three-lobe bearing spindle technology: a drive technology to increase aerial density

Cited by 5 publications

References 5 publications

Vibration control of an HDD disk-spindle system utilizing piezoelectric bimorph shunt damping: I. Dynamic analysis and modeling of the shunted drive

Vibration control of an HDD disk-spindle system utilizing piezoelectric bimorph shunt damping: I. Dynamic analysis and modeling of the shunted drive

Analysis and design of hydrodynamic journal air bearings for high performance HDD spindle

Stability analysis of a disk-spindle supported by a plain journal bearing and pivot bearing

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