WO2003099497A1 - Procede et dispositif pour former des tourillons rainures - Google Patents

Procede et dispositif pour former des tourillons rainures Download PDF

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Publication number
WO2003099497A1
WO2003099497A1 PCT/US2003/016988 US0316988W WO03099497A1 WO 2003099497 A1 WO2003099497 A1 WO 2003099497A1 US 0316988 W US0316988 W US 0316988W WO 03099497 A1 WO03099497 A1 WO 03099497A1
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WO
WIPO (PCT)
Prior art keywords
electrode
fluid
bearing
journal bearing
gap
Prior art date
Application number
PCT/US2003/016988
Other languages
English (en)
Inventor
Dustin Cochran
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 WO2003099497A1 publication Critical patent/WO2003099497A1/fr

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Classifications

    • 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
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
    • F16C33/107—Grooves for generating pressure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H3/00—Electrochemical machining, i.e. removing metal by passing current between an electrode and a workpiece in the presence of an electrolyte
    • B23H3/04—Electrodes specially adapted therefor or their manufacture
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H9/00—Machining specially adapted for treating particular metal objects or for obtaining special effects or results on metal objects
    • 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
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
    • F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
    • 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
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/14—Special methods of manufacture; Running-in
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23H—WORKING OF METAL BY THE ACTION OF A HIGH CONCENTRATION OF ELECTRIC CURRENT ON A WORKPIECE USING AN ELECTRODE WHICH TAKES THE PLACE OF A TOOL; SUCH WORKING COMBINED WITH OTHER FORMS OF WORKING OF METAL
    • B23H2200/00—Specific machining processes or workpieces
    • B23H2200/10—Specific machining processes or workpieces for making bearings
    • 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 invention relates generally to the field of disc drives, and more particularly to an apparatus and method for forming hydrodynamic grooves in a disc drive.
  • Disc drives are capable of storing large amounts of digital data in a relatively small area.
  • Disc drives store information on one or more recording media.
  • the recording media conventionally takes the form of a circular storage disc, e.g., media, having a plurality of concentric circular recording tracks.
  • a typical disc drive has one or more discs for storing information. This information is written to and read from the discs using read/write heads mounted on actuator arms that are moved from track to track across surfaces of the discs by an actuator mechanism.
  • the discs are mounted on a spindle that is turned by a spindle motor to pass the surfaces of the discs under the read/write heads.
  • the spindle motor generally includes a shaft fixed to a base plate and a hub, to which the spindle is attached, having a sleeve into which the shaft is inserted.
  • Permanent magnets attached to the hub interact with a stator winding on the base plate to rotate the hub relative to the shaft.
  • one or more bearings are usually disposed between the hub and the shaft.
  • the read/write heads must be placed increasingly close to the surface of the storage disc. This proximity requires that the disc rotate substantially in a single plane. A slight wobble or run-out in disc rotation can cause the surface of the disc to contact the read/write heads. This is known as a "crash" and can damage the read/write heads and surface of the storage disc resulting in loss of data.
  • bearing assembly which supports the storage disc is of critical importance.
  • One typical bearing assembly comprises ball bearings supported between a pair of races which allow a hub of a storage disc to rotate relative to a fixed member.
  • ball bearing assemblies have many mechanical problems such as wear, run-out and manufacturing difficulties. Moreover, resistance to operating shock and vibration is poor because of low damping.
  • One alternative bearing design is a hydrodynamic bearing.
  • a lubricating fluid such as air or liquid provides a bearing surface between a fixed member of the housing and a rotating member of the disc hub.
  • typical lubricants include oil or other fluids.
  • Hydrodynamic bearings spread the bearing interface over a large surface area in comparison with a ball bearing assembly, which comprises a series of point interfaces. This is desirable because the increased bearing surface reduces wobble or run-out between the rotating and fixed members. Further, the use of fluid in the interface area imparts damping effects to the bearing which helps to reduce non-repeat run out.
  • Dynamic pressure-generating grooves i.e., hydrodynamic grooves
  • journals, thrust, and conical hydrodynamic bearings generate localized area of high fluid pressure and provide a transport mechanism for fluid or air to more evenly distribute fluid pressure within the bearing, and between the rotating surfaces.
  • the shape of the hydrodynamic grooves is dependant on the pressure uniformity desired.
  • the quality of the fluid displacement and therefore the pressure uniformity is generally dependant upon the groove depth and dimensional uniformity. For example, a hydrodynamic groove having a non-uniform depth may lead to pressure differentials and subsequent premature hydrodynamic bearing or journal failure.
  • ECM electrochemical machining
  • the work piece may be misaligned with the electrode causing an uneven gap and a correspondingly uneven depth hydrodynamic groove. Therefore, it is almost impossible to make a tool with fixed electrodes that will guarantee a continued consistent work piece to electrode gap to form dimensionally consistent hydrodynamic grooves.
  • Embodiments of the present invention relate to a method and apparatus for electromechanically etching grooves in a surface of a conical bearing'.
  • the invention provides a method for aligning an electrode haying one or more hydrodynamic bearing groove patterns thereon within a hydrodynamic bearing. The method includes positioning the electrode within a hydrodynamic bearing, and providing a fluid pressure between the electrode and the hydrodynamic bearing to align the electrode and the hydrodynamic bearing.
  • the invention provides an apparatus for forming grooves within a hydrodynamic bearing.
  • the apparatus includes a fluidstatic bearing configured to support at least a portion of an electrode having at least one surface carrying a groove pattern to electrochemically etch on an inner surface'of the hydrodynamic bearing.
  • the fluid static bearing utilizes a pressurable medium which may comprise liquid or air.
  • the apparatus includes a fluid input configured to couple a fluid flow in a gap between at least some of the electrode and an inner surface of the hydrodynamic bearing to adjust the width of the gap, and a source of electrolyte to be pumped within the gap.
  • the invention provides an apparatus for electrochemically forming grooves on a hydrodynamic bearing, including means for fluidly supporting an electrode having a groove pattern thereon, and means for fluidly aligning the electrode within a hydrodynamic bearing.
  • Figure 1 depicts a plan view of one embodiment of a disc drive for use with aspects of the invention.
  • Figure 2 is a vertical sectional depicting one embodiment of a dual conical bearing utilized in the disc drive of Figure 1 for use with aspects of the invention.
  • Figure 3 depicts a simplified sectional view of an electrochemical machining system for use with aspects of the invention.
  • Figure 4 depicts a partial sectional view of an electrochemical machining system for use with aspects of the invention.
  • Figure 1 depicts a plan view of one embodiment of a disc drive 10 for use with embodiments of the invention.
  • the disc drive 10 includes a housing base 12 and a top cover 14.
  • the housing base 12 is combined with top cover 14 to form a sealed environment to protect the internal components from contamination by elements from outside the sealed environment.
  • the base and top cover arrangement shown in Figure 1 is well known in the industry. However, other arrangements of the housing components have been frequently used, and aspects of the invention are not limited to the configuration of the disc drive housing. For example, disc drives have been manufactured using a vertical split between two housing members.
  • Disc drive to further includes a disc pack 16 which is mounted on a hub 202 (See Figure 2) for rotation on a spindle motor (not shown) by a disc clamp 18.
  • Disc pack 16 includes a plurality of individual discs that are mounted for co-rotation about a central axis. Each disc surface has an associated read/write head 20 which is mounted to disc drive 10 for communicating with the disc surface.
  • read/write heads 20 are supported by flexures 22 which are in turn attached to head mounting arms 24 of an actuator body 26.
  • the actuator shown in Figure 1 is of the type known as a rotary moving coil actuator and includes a voice coil motor (VCM), shown generally at 28.
  • VCM voice coil motor
  • Voice coil motor 28 rotates actuator body 26, with its attached read/write heads 20 about a pivot shaft 30 to position read/write heads 20 over a desired data track along a path 32.
  • Figure 2 is a vertical sectional view of a hub 202 supported by dual conical and journal bearing 200 for rotation about a shaft not shown.
  • the hub 202 is integrated with the sleeve 204.
  • the sleeve 204 includes internal surfaces 206 having grooved regions 214, 216 forming the hydrodynamic bearing to support the hub during rotation.
  • a shaft (not shown) is inserted within the sleeve 204 and has dual conical surfaces which face the conical regions 210, 212 at the upper and lower ends of the journal bearing 200.
  • the shaft would further include a smooth center section which would cooperate with a portion of the journal bearing 200 defined by the grooved regions 214, 216.
  • fluid will fill the gap between the stationary shaft and the inner grooved surfaces of the sleeve 204.
  • FIG 3 is a simplified illustration of a groove forming apparatus 300 and method for making hydrodynamic grooves 222.
  • Figure 2 may be referenced as needed in the discussion of Figure 3.
  • the illustrative apparatus and method are described in terms of hydrodynamic grooves 222.
  • the present invention is not limited to making this particular combination of hydrodynamic grooves 222.
  • the apparatus and method described could be used to make the hydrodynamic grooves (e.g., grooves) 222 inside a single cone or a single cone cooperating with a single journal bearing or dual cones cooperating with one or more journal bearings 200.
  • each of the conical bearings could have one or more sets of hydrodynamic grooves 222.
  • a fluid dynarhic bearing generally comprises two relatively rotating members having juxtaposed surfaces between which a layer or film or fluid is maintained to form a dynamic cushion with an antifriction medium.
  • a fluid dynarhic bearing generally comprises two relatively rotating members having juxtaposed surfaces between which a layer or film or fluid is maintained to form a dynamic cushion with an antifriction medium.
  • the surfaces in this case the interior surfaces of sleeve 204, are provided with the hydrodynamic grooves 222 which induce fluid flow in the interfacial region and generate a localized region of dynamic high pressure.
  • groove-forming apparatus 300 includes an fluidstatic bearing 306.
  • Fluidstatic bearing 306 includes an air inlet 308 to receive fluid 310 such as pressurized air, clean dry air (CDA), liquid and the like.
  • Internal surfaces 307 of fluidstatic bearing 306 define a longitudinal bore 309.
  • Longitudinal bore 309 inside diameter is sized to hold a floating electrode 302 therein.
  • Floating electrode 302 has an outside diameter sized smaller than longitudinal bore 307 to define a gap 316 there between.
  • Fluid flow through inlet 308 into gap 316 is at sufficient viscosity or pressure provides force FX1 between internal surfaces 307 and floating electrode 302.
  • FX1 is of a magnitude capable of supporting floating electrode 302 to maintain gap 316.
  • pressure within gap 316 between internal surfaces 307 and floating electrode 302 center and support such floating electrode 302 within longitudinal bore 309.
  • Fluidstatic bearing 306 may include one or more end walls not shown to prevent floating electrode 306 from moving outside longitudinal bore 309.
  • Floating electrode 302 includes an extension 304 extending from one end thereof.
  • Extension 304 has an outside diameter sized to fit within an inside diameter of journal bearing 200 (i.e., work piece) to form a fluid gap 322 there between.
  • the journal bearing 200 is rigidly held in place by a clamping apparatus not shown.
  • Extension 304 is configured with a hydrodynamic journal pattern 324 juxtaposed to inside surfaces 206.
  • Hydrodynamic journal pattern 324 may be used to form hydrodynamic grooves 222 on the journal bearing 200, for example.
  • electrolyte 320 is pumped through an electrolyte inlet 321 into fluid gap 322.
  • electrolyte 320 is generally non- compressible, electrolyte 320 fills fluid gap 322 centering electrode extension 304 within journal bearing 200.
  • electrolyte 320 is used to center the extension 304 within journal bearing 200.
  • Floating electrode 302 may further include a fluid delivery bore 315 extending axially there through, and at least partially through extension 304.
  • Fluid delivery bore 315 includes a positioning fluid inlet 314 on one end and a plurality of fluid jets 328A-C coupled to an opposite end of fluid bore 315.
  • Fluid jets 328A-C are disposed so that positioning fluid 312 received from fluid inlet 314 exits at least partially against an inside surfaces 206 of journal bearing 200.
  • Fluid jets 328A-C may be angled at an angle ⁇ approximately 45 degrees relative the inside surfaces 206 they contact.
  • Positioning fluid 312 may be any fluid configured to work with electrolyte 320, and may be an electrolyte similar to or the same as electrolyte 320.
  • fluid jets 328A-C may be radially spaced approximately uniformly about extension 304 so that positioning fluid 312 discharged from fluid jets 328A-C provide uniform centering forces FX2 and FY2 against the journal bearing 200. Positioning fluid 312 exits from fluid gap 322 via an end of journal bearing 200. During another alignment operation of extension 304 within journal bearing 200, positioning fluid 312 is pumped though fluid inlet 314 and forced through fluid jets 328A-C. Fluid forces FX2 and FY2 balance force FX1 in an equilibrium condition so that extension 304 is horizontally and vertically centered within journal bearing 200.
  • fluid jets 328A-C are illustrated spaced so the angle ⁇ is approximately 120 degrees apart to provide an equal fluid force FX2 to center the extension 304 within the journal bearing 200, any number or configuration of fluid jets 328 may be used to provide such centering and aligning forces.
  • the ECM process can then be executed by then applying an electrical potential to the work piece 200 and floating electrode 302, the work piece receiving the positive potential and the floating electrode 302 serving as the cathode and receiving the negative potential.
  • an imprint in the form of the groove patterns 222 shown in Fig. 2 are placed on the work piece 200.
  • the width and depth of the resulting hydrodynamic grooves 222 - is controlled by the duration and level of current applied to the work piece 200 and the floating electrode 302.
  • the current level being modified primarily by the fluid gap 322 which has now been adjusted by fluidstatic bearing 306, electrolyte 320, and positing fluid 312 via fluid jets 328A-C.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Manufacturing & Machinery (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Sliding-Contact Bearings (AREA)
  • Magnetic Bearings And Hydrostatic Bearings (AREA)

Abstract

Certains modes de réalisation de l'invention concernent un procédé et un dispositif pour former des rainures sur des paliers hydrodynamiques utilisés dans un lecteur de disques. Un mode de réalisation de l'invention concerne un procédé et un dispositif pour aligner une électrode sur laquelle est formé un motif de rainure hydrodynamique, dans un palier de tourillon. L'invention comprend une électrode flottante sur laquelle sont formés des motifs de rainure. L'électrode flottante est insérée dans le palier de tourillon et alignée de façon fluide pour maintenir un espacement uniforme entre les deux.
PCT/US2003/016988 2002-05-28 2003-05-28 Procede et dispositif pour former des tourillons rainures WO2003099497A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US38394902P 2002-05-28 2002-05-28
US60/383,949 2002-05-28
US10/242,336 US20030221959A1 (en) 2002-05-28 2002-09-11 Method and apparatus for forming grooved journals
US10/242,336 2002-09-11

Publications (1)

Publication Number Publication Date
WO2003099497A1 true WO2003099497A1 (fr) 2003-12-04

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WO (1) WO2003099497A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7144482B2 (en) * 2003-01-21 2006-12-05 Seagate Technology Llc Method and apparatus for forming grooves within journals and on flat plates
US20040140226A1 (en) * 2003-01-21 2004-07-22 Cochran Dustin Alan Critical orifice gap setting for ECM grooving of flat plates
DE102011014364A1 (de) * 2011-03-17 2012-09-20 Stoba Präzisionstechnik Gmbh & Co. Kg Verfahren und Vorrichtung zum elektrochemischen Bearbeiten von Werkstücken
US9070007B2 (en) * 2013-01-11 2015-06-30 Datalogic ADC, Inc. Adjustable data reader with pivot mount

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1054934A (fr) * 1962-10-04
US3637481A (en) * 1968-09-24 1972-01-25 Anocut Eng Co Electrolytic demetallizing apparatus having electrolyte-pressure-responsive load-compensating means
GB2319741A (en) * 1996-11-28 1998-06-03 Loadpoint Limited Method and apparatus for forming recesses in a bearing surface
JPH10180545A (ja) * 1996-12-24 1998-07-07 Sankyo Seiki Mfg Co Ltd 動圧軸受における動圧溝の電解加工方法及び電解加工装置
US6251257B1 (en) * 1999-01-29 2001-06-26 Seagate Technology Llc Apparatus and method for electrochemically etching grooves in an outer surface of a shaft
US20010050235A1 (en) * 1998-06-04 2001-12-13 Seagate Technology Llc. Electrode design for electrochemical machining of grooves
US6358394B1 (en) * 1999-05-07 2002-03-19 Seagate Technology Llc Apparatus and method for manufacturing fluid dynamic bearings

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH462981A (fr) * 1967-04-28 1968-09-30 Charmilles Sa Ateliers Dispositif d'avance et de guidage rectilignes de l'électrode dans une machine à usiner par électro-érosion
US5104237A (en) * 1990-11-08 1992-04-14 Advanced Engineering Systems Operations & Products, Inc. (Aesop) Self-compensating hydrostatic linear motion bearing
US5616259A (en) * 1994-12-27 1997-04-01 Ford Motor Company Apparatus for preparing a surface of a cylinder bore by electrical discharge machining

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1054934A (fr) * 1962-10-04
US3637481A (en) * 1968-09-24 1972-01-25 Anocut Eng Co Electrolytic demetallizing apparatus having electrolyte-pressure-responsive load-compensating means
GB2319741A (en) * 1996-11-28 1998-06-03 Loadpoint Limited Method and apparatus for forming recesses in a bearing surface
JPH10180545A (ja) * 1996-12-24 1998-07-07 Sankyo Seiki Mfg Co Ltd 動圧軸受における動圧溝の電解加工方法及び電解加工装置
US20010050235A1 (en) * 1998-06-04 2001-12-13 Seagate Technology Llc. Electrode design for electrochemical machining of grooves
US6251257B1 (en) * 1999-01-29 2001-06-26 Seagate Technology Llc Apparatus and method for electrochemically etching grooves in an outer surface of a shaft
US6358394B1 (en) * 1999-05-07 2002-03-19 Seagate Technology Llc Apparatus and method for manufacturing fluid dynamic bearings

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 1998, no. 12 31 October 1998 (1998-10-31) *

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