EP0912976A1 - Moteur de memoire a disque dont les roulements sont lubrifies avec un lubrifiant non susceptible d'etalement - Google Patents

Moteur de memoire a disque dont les roulements sont lubrifies avec un lubrifiant non susceptible d'etalement

Info

Publication number
EP0912976A1
EP0912976A1 EP96924561A EP96924561A EP0912976A1 EP 0912976 A1 EP0912976 A1 EP 0912976A1 EP 96924561 A EP96924561 A EP 96924561A EP 96924561 A EP96924561 A EP 96924561A EP 0912976 A1 EP0912976 A1 EP 0912976A1
Authority
EP
European Patent Office
Prior art keywords
disc
lubricant
disc drive
additive
bearing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP96924561A
Other languages
German (de)
English (en)
Inventor
Gregory I. Rudd
Raquib U. Khan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Seagate Technology LLC
Original Assignee
Seagate Technology LLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Seagate Technology LLC filed Critical Seagate Technology LLC
Publication of EP0912976A1 publication Critical patent/EP0912976A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B19/00—Driving, starting, stopping record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof; Control of operating function ; Driving both disc and head
    • G11B19/20—Driving; Starting; Stopping; Control thereof
    • G11B19/2009—Turntables, hubs and motors for disk drives; Mounting of motors in the drive
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/66—Special parts or details in view of lubrication
    • F16C33/6603—Special parts or details in view of lubrication with grease as lubricant
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/66—Special parts or details in view of lubrication
    • F16C33/6696—Special parts or details in view of lubrication with solids as lubricant, e.g. dry coatings, powder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16N—LUBRICATING
    • F16N15/00—Lubrication with substances other than oil or grease; Lubrication characterised by the use of particular lubricants in particular apparatus or conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2370/00—Apparatus relating to physics, e.g. instruments
    • F16C2370/12—Hard disk drives or the like

Definitions

  • the present invention relates to disc drives. More specifically, the present invention relates to a motor used in a disc drive.
  • a typical disc drive includes one or more magnetic discs mounted for rotation on a hub or spindle.
  • a typical disc drive also includes one or more transducers supported by a hydrodynamic air bearing which flies above each magnetic disc. The transducers and the hydrodynamic air bearing are collectively referred to as a data head.
  • a drive controller is conventionally used for controlling the disc drive system based on commands received from a host system. The drive controller controls the disc drive to retrieve information from the magnetic discs and to store information on the magnetic discs.
  • An electromechanical actuator operates within a negative feedback, closed-loop servo system.
  • the actuator moves the data head radially over the disc surface for track seek operations and holds the transducer directly over a track on the disc surface for track following operations.
  • Information is typically stored on the magnetic discs by providing a write signal to the data head to encode flux reversals on the surface of the magnetic disc representing the data to be stored.
  • the drive controller controls the electromechanical actuator so that the data head flies above the magnetic disc, sensing the flux reversals on the magnetic disc, and generating a read signal based on those flux reversals.
  • the read signal is then decoded by the drive controller to recover the data represented by flux reversals stored on a magnetic disc, and consequently represented in the read signal provided by the data head.
  • the most commonly used type of actuator is a rotary moving coil actuator.
  • the discs themselves are typically mounted in a "stack" on the hub structure of a brushless DC spindle motor.
  • the rotational speed of the spindle motor is precisely controlled by motor drive circuitry which controls both the timing and the power of commutation signals directed to the stator windings of the motor.
  • the hub structure is rotatably coupled to a shaft via a set of bearings.
  • the hub includes a sleeve or back iron portion which carries a magnet. Interaction between the magnet and the stator causes controlled rotation of the hub about the shaft.
  • the bearings in the spindle motor are typically lubricated with a material that provides a fluid film which separates the bearing surfaces.
  • Such bearings are conventionally small, grease lubricated ball bearings, self-pumping hydrodynamic fluid bearings, or oil-saturated porous metal bushings.
  • barrier films have also been used in an attempt to control migration. Such films repel oil and are typically applied to surfaces where oil is not desired. However, barrier films are usually invisible and are therefore difficult to apply with any reasonable degree of control. Further, application of such films requires an additional manufacturing step, which is also undesirable.
  • Non-spreading oils referred to as "autophobic" oils are also known in other industries. These oils are principally used in the clock making industry. Autophobic oils do not readily wet their own films and therefore show much less tendency to spread.
  • clock oils have relatively high viscosity and surface tensions and are formulated with natural oils containing polar compounds such as esters and fatty acids . These oils are not suitable for the lifetime lubrication of a computer disc drive spindle bearing due to the high power consumption associated with the high viscosity properties of the oils and because the oils are incompatible with the head disc interface.
  • a disc drive includes a disc and a motor having a rotatable portion and a fixed portion.
  • the fixed portion and the rotatable portion are separated by a bearing, and the rotatable portion supports the disc.
  • a data transducer is coupled to an actuator to move relative to the disc to access different portions of the disc.
  • the bearing includes a lubricant having an additive of perfluoropolyether with a reactive end group.
  • FIG. 1 is a block diagram of disc drive 10 according to the present invention.
  • FIG. 2 is a side sectional view of one embodiment of a disc drive motor according to the present invention.
  • FIG. 1 is a block diagram of disc drive 10 according to the present invention.
  • Disc drive 10 includes drive controller 12, servo control processor 14, power amplifier 16, actuator assembly 18, disc stack assembly 20, preamplifier 22, data and clock recovery circuit 24, and error detection circuit 26.
  • Drive controller 12 is typically a microprocessor, or digital computer, and is coupled to a host system, or another drive controller which controls a plurality of drives.
  • Disc stack assembly 20 includes spindle 28 which supports a plurality of coaxially arranged discs 30. The discs are mounted for rotation with spindle 28 about axis of rotation 29. Each of the discs 30 has a first surface 32 and a second surface 34.
  • Surfaces 32 and 34 both include concentric tracks for receiving and storing data in the form of flux reversals encoded on the tracks.
  • a group of tracks which includes one track per surface 32 and 34, wherein each track in the group is located a common radial distance from the inner diameter of the corresponding disc 30 upon which it resides, is referred to as a cylinder.
  • Actuator assembly 18 includes an actuator 36 supporting a plurality of actuator arms 38. Each of the actuator arms 38 is rigidly coupled to at least one head gimbal assembly 40. Each head gimbal assembly includes a load beam, or flexure arm, rigidly coupled to actuator arm 38 at a first end thereof, and to a gimbal at a second end thereof. The gimbal is, in turn, coupled to a hydrodynamic air bearing which supports a data head above the corresponding disc surface, 32 or 34, for accessing data within the tracks on the disc surface.
  • Actuator 36 is rotatably mounted with respect to discs 30. As actuator 36 rotates, it moves the transducers coupled to the head gimbal assemblies 40 either radially inward, toward an inner radius of the corresponding disc 30, or radially outward, toward an outer radius of the corresponding disc 30. In this way, actuator 38 positions the transducers on head gimbal assemblies 40 over a desired track (and cylinder) on the discs 30.
  • drive controller 12 typically receives a command signal from a host system which indicates that a certain portion of a disc 30 on disc stack assembly 20 is to be accessed.
  • drive controller 12 provides servo control processor 14 with a position signal which indicates a particular cylinder over which actuator 36 is to position head gimbal assemblies 40.
  • Servo control processor 14 converts the position signal into an analog signal which is amplified by power amplifier 16 and provided to actuator assembly 18.
  • actuator 18 positions head gimbal assemblies 40 over a desired cylinder.
  • the command signal from drive controller 12 also indicates the particular sector to be read from or written to. If the particularly identified disc and sector are to be read, the read transducer on the corresponding head gimbal assembly 40 generates a read signal containing the data.
  • the read signal is provided to a preamplifier 22 which amplifies the read signal and provides it to data and clock recovery circuit 24.
  • Data and clock recovery circuit 24 recovers data, which is encoded on the disc surface when the data is written to the disc surface. The data is recovered from the read signal provided by preamplifier 22. Data and clock recovery circuit 24 operates in a known manner.
  • error detection circuit 26 which, in this preferred embodiment, is based on an error correction code (ECC) , such as a Reed-Solomon code. Error detection circuit 26 detects whether any errors have occurred in the data read back from the disc.
  • ECC error correction code
  • drive controller 12 provides a position signal to servo control processor 14 causing actuator assembly 18 to position the head gimbal assemblies 40 over a selected cylinder (for coarse positioning) , and at a desired relative position within a track (for fine positioning) .
  • FIG. 2 is a side sectional view of a disc drive motor 42 according to the present invention.
  • Drive motor 42 is used as a spindle motor to rotate spindle 28 and includes a base 44 and a shaft 46 fixedly attached to base 44.
  • An axis of rotation 48 is generally defined by the longitudinal axis of shaft 46.
  • Motor 42 also includes rotor assembly 50.
  • Rotor assembly 50 includes bearings 52 and 54, bearing holder 56, hub 58 and magnet 60.
  • Bearings 52 and 54 are disposed about shaft 46 and are supported by bearing holder 56.
  • Labyrinth seal 62 and Ferro-fluid seal 64 are disposed generally at opposite axial ends of bearing holder 56 and seal a bearing compartment 66 which holds bearings 52 and 54.
  • Hub 58 is fixedly coupled to bearing holder 56 and has a flange 68.
  • Flange 68 supports magnetic discs 30 for rotation about axis 48.
  • Bearing holder 56 includes a back iron or sleeve portion 70 which is generally cylindrical in shape and is preferably formed integrally with bearing holder 56.
  • Seal holder 72 is formed of a non-magnetic material and is mounted to an inner surface of sleeve 70 to support Ferro-fluid seal 64.
  • Sleeve 70 has an outer periphery defined by a generally cylindrical surface 74.
  • Magnet 76 is coupled to outer surface 74 of sleeve 70.
  • Magnet 76 is a generally annular-shaped magnet disposed about outer surface 74.
  • Stator windings 78 are rigidly attached to base 44 and are selectively provided with commutation signals. Interaction between the magnetic field generated by stator 78 and magnet 76 causes controlled rotation of rotor assembly 50 about shaft 46.
  • Bearings 52 and 54 are lubricated with one of a number of commercially available lubricants .
  • the disc drive industry has developed several lubricants (liquids and greases, such as Multe p SRL) that have excellent properties in miniature bearings including excellent compatibility with the head-disc interface. These lubricants are based primarily on natural and synthetic hydrocarbons and synthetic ester lubricants. All show varying, but similar, tendency to migrate from bearings 52 and 54.
  • the PFPEs that provide this benefit include reactive end groups .
  • the reactive end group is a chemical structure that is intended to chemically bond to a surface, anchoring the PFPE molecule in place .
  • Examples of PFPEs with reactive end groups are commercially available as a series of PFPEs under the commercial designation FOMBLIN Z produced by Montefluos SpA/Ausimont , of Morristown, New Jersey.
  • Other PFPEs with reactive end groups are commercially available under the commercial designation DEMNUM from Daikin Chemical Company, of Osaka, Japan.
  • the particular commercial designation, and the chemical structure, along with the typical characteristics of a number of the PFPEs are shown in Table 1.
  • the above PFPEs shown in Table 1 have been tested and adequately perform according to the present invention. Also, the above PFPEs are compatible with the head-disc interface in the disc drive.
  • the additive FOMBLIN Z-DOL was blended into a commercially available refined paraffinic petroleum hydrocarbon that has otherwise been proven suitable as a hydrodynamic bearing fluid.
  • the additive was blended in several amounts between, and including, about 0.05% by volume and 1% by volume of the additive with respect to the bulk lubricant material. The spreading and migration tendency of the mixture was greatly reduced over that of the original oil lubricant. The area covered by a droplet of the lubricant containing the additive after
  • FOMBLIN AM-2001 was blended into the same refined paraffinic petroleum hydrocarbon. The results were the same as for the lubricant containing the FOMBLIN Z-DOL additive.
  • FOMBLIN AM-2001 was blended into a commercially available synthetic ester lubricant that has been found to be a superior fluid for use in miniature self-pumping hydrodynamic bearings.
  • the fluid was found to have a slightly greater tendency to migrate than did the refined paraffinic petroleum fluid containing the additive.
  • significant improvement was obtained over lubricants containing no additive.
  • a number of concentrations were mixed such that the additive made up between (and including) about 0.05% and 1% by volume of the bulk lubricant material.
  • the area covered by a droplet containing the additive after 96 hours at room temperature on a stainless steel block was only about 40% of that covered by the oil with no antimigration additive under the same conditions. Also, the fluid with the additive climbed a glass capillary only 70% as high as the fluid without the additive.
  • FOMBLIN Z-Dol was blended into a commercially available synthetic ester lubricant that has been found to be a superior fluid for use in miniature self-pumping hydrodynamic bearings.
  • the fluid was found to have a slightly greater tendency to migrate than did the -lirefined paraffinic petroleum fluid containing the additive.
  • significant improvement was obtained over lubricants containing no additive.
  • a number of concentrations were mixed such that the additive made up between (and including) about 0.05% and 1% by volume of the bulk lubricant material .
  • the area covered by a droplet containing the additive after 96 hours at room temperature on a stainless steel block was only about 40% of that covered by the oil with no antimigration additive under the same conditions. Also, the fluid with the additive climbed a glass capillary only 70% as high as the fluid without the additive.
  • FOMBLIN Z-DOL was blended with a high quality, commercially known and available, synthetic ester-based grease presently used in computer hard disc ball bearing spindle motors.
  • a small amount of grease (approximately 0.1 to 3 milligrams) was placed on a highly polished stainless steel block in a 70°C oven for 24 hours.
  • the grease without the additive showed oil spreading over an area equal to approximately 3-5 times the area covered by the grease. Substantially no base oil spreading was observed for grease containing the Z- DOL additive.
  • various concentrations of the additive were tried in a range of about 0.05% to 1% by volume.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Lubricants (AREA)

Abstract

Une mémoire à disque (10) comprend un disque (30) et un moteur présentant une partie rotative (50) et une partie fixe (46). La partie fixe (46) et la partie rotative (50) sont séparées par un roulement (52, 54), la partie rotative (50) soutenant le disque (30). Un transducteur de données est couplé à un actionneur (36) pour se déplacer par rapport au disque (30) afin d'accéder à différentes parties du disque (30). Le roulement (52, 54) est pourvu d'un lubrifiant comprenant un additif constitué de perfluoropolyéther avec un groupe terminal réactif.
EP96924561A 1996-07-17 1996-07-17 Moteur de memoire a disque dont les roulements sont lubrifies avec un lubrifiant non susceptible d'etalement Withdrawn EP0912976A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1996/011820 WO1998002880A1 (fr) 1996-07-17 1996-07-17 Moteur de memoire a disque dont les roulements sont lubrifies avec un lubrifiant non susceptible d'etalement

Publications (1)

Publication Number Publication Date
EP0912976A1 true EP0912976A1 (fr) 1999-05-06

Family

ID=22255468

Family Applications (1)

Application Number Title Priority Date Filing Date
EP96924561A Withdrawn EP0912976A1 (fr) 1996-07-17 1996-07-17 Moteur de memoire a disque dont les roulements sont lubrifies avec un lubrifiant non susceptible d'etalement

Country Status (3)

Country Link
EP (1) EP0912976A1 (fr)
JP (1) JP2000514903A (fr)
WO (1) WO1998002880A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111173841A (zh) * 2020-01-03 2020-05-19 上海大学 高温滚动轴承气相和气/固相原位聚合固体润滑系统

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2001173667A (ja) 1999-12-20 2001-06-26 Koyo Seiko Co Ltd 転動装置
JP5347242B2 (ja) * 2007-06-04 2013-11-20 Ｄｉｃ株式会社 グリース基油拡散防止剤
JP2013014786A (ja) * 2012-10-24 2013-01-24 Dic Corp グリース基油拡散防止剤及びグリース基油
JP5780336B2 (ja) * 2014-04-21 2015-09-16 Dic株式会社 グリース基油拡散防止剤及びグリース基油

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US4604229A (en) * 1985-03-20 1986-08-05 Ferrofluidics Corporation Electrically conductive ferrofluid compositions and method of preparing and using same
GB8612983D0 (en) * 1986-05-28 1986-07-02 Chambers R D Polyether compounds
US4789913A (en) * 1987-08-03 1988-12-06 International Business Machines Corporation Method and apparatus for lubricating a magnetic disk continuously in a recording file
US5271631A (en) * 1989-05-31 1993-12-21 Atsushi Yokouchi Magnetic fluid seal apparatus
JP2580344B2 (ja) * 1989-10-25 1997-02-12 日本精工株式会社 磁性流体組成物とその製造方法及び磁性流体シ―ル装置
EP0515687A4 (en) * 1990-10-25 1993-11-24 Ebara Corporation Gas dynamic bearing
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US5663127A (en) * 1994-07-29 1997-09-02 Minnesota Mining And Manufacturing Company Perfluoropolyether lubricating compositions

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111173841A (zh) * 2020-01-03 2020-05-19 上海大学 高温滚动轴承气相和气/固相原位聚合固体润滑系统
CN111173841B (zh) * 2020-01-03 2022-01-07 上海大学 高温滚动轴承气相和气/固相原位聚合固体润滑系统

Also Published As

Publication number Publication date
WO1998002880A1 (fr) 1998-01-22
JP2000514903A (ja) 2000-11-07

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