Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic phosphorus compound – wherein the phosphorus is...
Reexamination Certificate
1998-12-22
2001-02-27
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic phosphorus compound, wherein the phosphorus is...
C508S100000, C360S099080, C360S099040, C360S098070, C310S06700R, C310S090000
Reexamination Certificate
active
06194360
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic recording device having an improved spindle motor lubricant.
2. Description of the Background Art
Current growth rates for digital magnetic recording data storage industry show a significant annual increase in recording densities and transfer rate and a decrease in seek time. To continue on this growth rate curve, the recording industry is being forced to make a number of significant changes in the design and operation of the magnetic recording device. Digital magnetic recording devices for data storage generally comprise a thin film magnetic recording disk, a spindle motor for rotating the disk, and a head or transducer which is moved along or above the surface of the rotating disk to read and write information on the disk. The thin film magnetic recording disks generally comprise a substrate, a magnetic layer such as a cobalt-based metal alloy, a protective amorphous carbon layer and a layer of perfluoropolyether disposed on the carbon overcoat. The magnetic recording disks are mounted on a spindle motor which rotates the disk at a high rotational speed. The spindle motor generally comprises (i) a spindle shaft attached to a housing, (ii) a spindle hub rotatably mounted on the shaft, and (iii) lubricated ball bearings positioned in races formed in the shaft and/or hub.
The head or transducer is attached to a carrier or slider having an air bearing surface which is supported during operation adjacent the data surface of the disk by a cushion of air generated by the rotating disk.
The recording device also comprises a positioning actuator connected to the carrier for moving the head to the desired location on the disk during reading or writing operations.
Conventional magnetic recording devices are operated at a rotational speed of about 3,600 RPM to 7,000 RPM. It has been discovered that during normal operation of the disk drive at higher rotational speeds, e.g., >7,500 RPM, the recording device begins to undergo acoustic vibrations associated with chemical breakdown of the spindle bearing grease lubricant within a short period of time. Continued operation of the recording device in the presence of the acoustic vibrations leads to mechanical failure of the spindle bearing.
It is an object of the present invention to provide an improved magnetic recording device which operates for extended periods of time at higher rotational speeds without unacceptable acoustic vibrations.
Other objects and advantages will be apparent from the following disclosure.
SUMMARY OF THE INVENTION
The present invention relates to a digital magnetic recording data storage device which can operate effectively at high rotational speeds. The magnetic recording device of the present invention comprises (a) a magnetic recording disk; (b) a spindle motor associated with the disk operable for rotating the disk at selected rotational speeds of 3,000 RPM to >7,000 RPM, e.g., 10,000-20,000 RPM; (c) a head supported on an air bearing carrier (head and carrier are an integral member) for magnetically writing data to or magnetically reading data from the magnetic layer on the disk; and (d) an actuator connected to the head carrier for moving the head across the rotating disk. The spindle motor is preferably a brushless direct current spindle motor comprising (i) a spindle shaft attached to a housing, (ii) a spindle hub rotatably mounted on the shaft, and (iii) ball bearings positioned in races formed in the shaft and/or hub and lubricated by an improved grease. The improved grease is the key feature of the present invention. The improved grease comprises a polymeric amine and bis or tris (alkyl phenyl)phosphate. The grease improves the rotational operation of the disk drive.
REFERENCES:
patent: 3869394 (1975-03-01), Daniels et al.
patent: 3970570 (1976-07-01), Pratt et al.
patent: 4096079 (1978-06-01), Pardee
patent: 4551258 (1985-11-01), Ikeda et al.
patent: 4780229 (1988-10-01), Mullin
patent: 4841393 (1989-06-01), MacLeod et al.
patent: 4879052 (1989-11-01), Mullin
patent: 4894740 (1990-01-01), Chhabra et al.
patent: 5296981 (1994-03-01), Ogawa
patent: 5438467 (1995-08-01), Dorius et al.
patent: 5448119 (1995-09-01), Kono et al.
patent: 5489711 (1996-02-01), Lai
patent: 5502605 (1996-03-01), Myokan
patent: 5560849 (1996-10-01), Shankwalkar et al.
patent: 5641841 (1997-06-01), Diaz et al.
patent: 5744431 (1998-04-01), Diaz et al.
patent: 5907456 (1999-05-01), Khan et al.
patent: 5930075 (1999-07-01), Khan
patent: 5940247 (1999-08-01), Karis et al.
patent: 11228985 (1999-08-01), None
patent: 11269475 (1999-10-01), None
R.L. Cottington et al., “Interactions in Neopentyl Polyol-Ester—Tricresyl Phosphate—Iron Systems at 500 F”, ASLE Transactions 12, Oct. 1969, pp. 280-286, Date unavailable.
F. Lockwood et al., “Ester Oxidation—The effect of an Iron Surface”, ASLE Transactions, vol. 25, 2, 1982, pp. 236-244, Date unavaiable.
Karis Thomas Edward
Nagaraj Holavanahally S.
Howard Jacqueline V.
International Business Machines - Corporation
Martin Robert B
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