JP2007102963A - Disk driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disk driving device equipped with a hub having high dimensional accuracy at a low cost. <P>SOLUTION: The lower end surface D1 of a disk D as an abutment surface is made to abut on a disk mounting surface 10d. The clamper 13 is fixed to a hub 10, and the clamper 13 is fastened to a shaft 2 by a screw 14, whereby the disk D receives clamping force from the clamper 13 and the hub 10 to be sandwiched and fixed. Simultaneously, the disk mounting surface 10d of the hub 10 receives pressing force from the lower end surface (abutment surface) D1 of the disk D. Thus, the disk D is fixed on the disk mounting surface 10d in a state where the disk mounting surface 10d is deformed along the lower end surface D1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a disk drive device including a hydrodynamic bearing device that supports a rotating member in a non-contact manner so as to be rotatable in a radial direction by a hydrodynamic action of a fluid generated in a radial bearing gap.

  In addition to high rotational accuracy, the disk drive device is required to have high speed, low cost, low noise, and the like. One of the components that determine the required performance is a bearing that supports the spindle of the motor. In recent years, the use of a hydrodynamic bearing having characteristics excellent in the required performance has been studied or actually used. Yes.

  For example, in a hydrodynamic bearing device incorporated in a disk drive device such as an HDD, both a radial bearing portion that supports a shaft member in the radial direction and a thrust bearing portion that supports the shaft member in the thrust direction may be configured by hydrodynamic bearings. As a radial bearing portion in this type of dynamic pressure bearing device, for example, a dynamic pressure groove as a dynamic pressure generating portion is formed on either the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member opposed to the bearing sleeve. In addition, there is known one that forms a radial bearing gap between both surfaces (see, for example, Patent Document 1).

Further, when the dynamic pressure bearing device is used by being incorporated in a disk drive device such as an HDD, a shaft is provided with a hub, and a disk-shaped information storage medium (hereinafter simply referred to as a disk) such as a magnetic disk is provided on the end surface of the hub. Is mounted and held (see, for example, Patent Document 2).
JP 2003-239951 A JP 2000-235766 A

  Incidentally, disk drive devices equipped with this type of hydrodynamic bearing device are required to have high rotational accuracy with the recent increase in accuracy of information equipment. The component parts are also required to have high dimensional accuracy. At the same time, it is necessary to reduce the manufacturing cost of the disk drive device as the price of information equipment decreases.

  In particular, when the disk drive device is used for an HDD, in order to obtain high disk reading accuracy, the dimensional accuracy of the hub that holds the disk, more precisely, the dimensional accuracy of the disk mounting surface on which the disk is placed is required. It becomes important. If the accuracy of the disk mounting surface is simply increased, high-accuracy machining of the disk mounting surface may be performed separately, but this increases the processing cost.

  The subject of this invention is providing the disk drive device provided with the hub part which has high dimensional accuracy at low cost.

  In order to solve the above-mentioned problems, the present invention provides a dynamic pressure action of a fluid generated in a rotary member having a shaft portion and a hub portion integrally or separately provided on the shaft portion, and a radial bearing gap facing the outer peripheral surface of the shaft portion. The hydrodynamic bearing device having a radial bearing portion that supports the rotating member in a non-contact manner so as to rotate freely in the radial direction, a disc that contacts the disc mounting surface of the hub portion and is fixed by a predetermined clamping force, and a disc mounted A disk drive device comprising a motor unit for rotating the rotating member, wherein the disk mounting surface is deformed following the contact surface of the disk by a clamping force.

  According to this configuration, when the disk is fixed, the disk mounting surface of the hub portion is corrected by the contact surface of the disk. Therefore, if a disk having such a contact surface finished with high accuracy is used, the dimensional accuracy of the disk mounting surface can be increased to the dimensional accuracy level of the disk without performing special high-precision processing. In particular, magnetic disks used in HDDs and the like are usually finished with high precision at their end faces in order to increase the reading accuracy of the disk head. The dimensional accuracy of the disk mounting surface can be increased in cost. Therefore, the disk can be fixed to the hub part while maintaining a high squareness with respect to the shaft part (rotating shaft), thereby improving the deflection accuracy of the disk during rotation.

  Moreover, it is preferable that the area including the disk mounting surface is molded of resin. Resin is generally less rigid than other materials (metals and ceramics), so depending on the thickness in the clamping direction, the disk mounting surface can be easily deformed to follow the disk contact surface. . For this reason, by forming with emphasis on formability (cycle time, etc.) rather than dimensional accuracy at the time of molding, it is possible to obtain a disk mounting surface that achieves both high dimensional accuracy and processing cost.

  As described above, according to the present invention, it is possible to provide a disk drive device including a hub portion having high dimensional accuracy at low cost.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 conceptually shows a configuration example of a disk drive device according to an embodiment of the present invention. This disk drive device is used, for example, in an HDD or the like. The disk drive device is connected to a hydrodynamic bearing device 1 that supports a rotating member 3 having a shaft portion 2 and a hub portion 10 in a non-contact manner in the radial direction, and, for example, via a radial gap. A motor unit including a stator coil 4 and a rotor magnet 5 opposed to each other, a bracket 6 and a disk D are provided. The stator coil 4 is attached to a bracket 6, and the rotor magnet 5 is fixed to the hub portion 10 via a yoke 12. The bearing member 7 of the fluid dynamic bearing device 1 is fixed to the inner periphery of the bracket 6. One or a plurality of disks D (one sheet in this example) are fixed to the hub portion 10. In this embodiment, the disk D is clamped and fixed by the hub portion 10 and the clamper 13. In the spindle motor configured as described above, when the stator coil 4 is energized, the rotor magnet 5 is rotated by the exciting force generated between the stator coil 4 and the rotor magnet 5. The disk D fixed to the portion 10 rotates integrally with the shaft portion 2.

  FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 mainly includes a bearing member 7, a lid member 11 that closes one end of the bearing member 7, and a rotating member 3 that rotates relative to the bearing member 7 and the lid member 11. For the sake of convenience of explanation, of the openings of the bearing member 7 formed at both ends in the axial direction, the side closed by the lid member 11 will be described as the lower side, and the side opposite to the closed side will be described as the upper side.

  The bearing member 7 has a shape in which both ends in the axial direction are open, and is a substantially cylindrical sleeve portion 8 and a housing portion that is positioned on the outer diameter side of the sleeve portion 8 and that is formed integrally with or separately from the sleeve portion 8. 9 and.

  The sleeve portion 8 is formed in a cylindrical shape with a porous body made of, for example, a metal non-porous body or sintered metal. In this embodiment, the sleeve portion 8 is formed in a cylindrical shape with a sintered metal porous body mainly composed of copper, and includes, for example, adhesion (including loose adhesion and press-fit adhesion) to the inner peripheral surface 9 c of the housing portion 9. ), Press-fitting, welding (for example, ultrasonic welding), or the like, and the like. Of course, the sleeve portion 8 can be formed of a material other than metal, such as resin or ceramic.

  A region where a plurality of dynamic pressure grooves are arranged as a radial dynamic pressure generating portion is formed on the entire inner surface or a partial cylindrical region of the inner peripheral surface 8 a of the sleeve portion 8. In this embodiment, for example, as shown in FIG. 3, two regions where a plurality of dynamic pressure grooves 8a1 and 8a2 are arranged in a herringbone shape are formed apart from each other in the axial direction.

  As shown in FIG. 4, for example, as shown in FIG. 4, a region in which a plurality of dynamic pressure grooves 8 b 1 are arranged in a spiral shape is formed on the entire lower surface 8 b of the sleeve portion 8 or a partial annular region.

  The housing part 9 is formed in a substantially cylindrical shape from metal or resin. In this embodiment, the housing part 9 has a shape in which both ends in the axial direction are opened, and one end side is sealed with the lid member 11. As the thrust dynamic pressure generating portion, for example, although not shown, a region where a plurality of dynamic pressure grooves are arranged in a spiral shape is formed on the entire end surface (upper end surface) 9a or a partial annular region on the other end side. . On the outer periphery of the upper portion of the housing portion 9 (the outer periphery of the end portion on the upper end surface 9a side), an annular tapered surface 9b that gradually increases in diameter upward is formed.

  The lid member 11 that seals the lower end side of the housing part 9 is made of metal or resin, and is fixed to a step part 9 d provided on the inner peripheral side of the lower end of the housing part 9. Here, the fixing means is not particularly limited. For example, means such as adhesion (including loose adhesion and press-fit adhesion), press-fit, welding (for example, ultrasonic welding), welding (for example, laser welding), combinations of materials and requirements Can be appropriately selected in accordance with the fixing strength, sealing performance, and the like.

  In this embodiment, the rotating member 3 mainly includes a shaft portion 2 inserted into the inner periphery of the sleeve portion 8 and a hub portion 10 provided at the upper end of the shaft portion 2 and disposed on the opening side of the bearing member 7. In preparation.

  The shaft portion 2 is made of metal in this embodiment, and is formed separately from the hub portion 10. The outer peripheral surface 2 a of the shaft portion 2 faces the dynamic pressure grooves 8 a 1 and 8 a 2 forming regions formed on the inner peripheral surface 8 a of the sleeve portion 8 in a state where the shaft portion 2 is inserted into the inner periphery of the sleeve portion 8. The outer peripheral surface 2a forms radial bearing gaps of first and second radial bearing portions R1 and R2, which will be described later, between the dynamic pressure grooves 8a1 and 8a2 when the shaft portion 2 rotates (FIG. 2). See).

  A flange portion 2b is provided separately at the lower end of the shaft portion 2 as a retaining member. The flange portion 2b is made of metal and is fixed to the shaft portion 2 by means such as screw connection. An upper end surface 2b1 of the flange portion 2b is opposed to a dynamic pressure groove 8b1 formation region formed in the lower end surface 8b of the sleeve portion 8, and a later-described second gap is formed between the dynamic pressure groove 8b1 formation region when the shaft portion 2 rotates. A thrust bearing gap of one thrust bearing portion T1 is formed (see FIG. 2).

  The hub part 10 projects to the outer diameter side from the disk part 10a that covers the opening side (upper side) of the bearing member 7, the cylindrical part 10b that extends downward in the axial direction from the outer peripheral part of the disk part 10a, and the cylindrical part 10b. A flange portion 10c and a disk mounting surface 10d formed at the upper end of the flange portion 10c are provided.

  The lower end surface 10a1 of the disk portion 10a is opposed to the upper end surface 9a (dynamic pressure groove 9a1 formation region) provided on the one end opening side of the housing portion 9, and when the shaft portion 2 rotates, A thrust bearing gap of a second thrust bearing portion T2 described later is formed therebetween (see FIG. 2).

  An inner peripheral surface 10b1 of the cylindrical portion 10b is opposed to a tapered surface 9b provided at the upper end of the outer periphery of the housing portion 9, and has a tapered shape in which the radial dimension gradually decreases upward between the tapered surface 9b. A seal space S is formed. In a state in which the lubricating oil described later is filled in the hydrodynamic bearing device 1, the oil level of the lubricating oil is always within the range of the seal space S.

  The hub portion 10 having the above-described configuration is formed of a resin composition using, as a base resin, a crystalline resin such as LCP, PPS, or PEEK, or an amorphous resin such as PPSU, PES, or PEI. In this embodiment, the hub portion 10 provided integrally with the shaft portion 2 is formed by injection molding using the shaft portion 2 as an insert part. Examples of fillers that can be added to the resin include fibrous fillers such as carbon fibers and glass fibers, whisker-like fillers such as potassium titanate, scaly fillers such as mica, carbon black, graphite, and carbon nano Examples thereof include conductive fillers such as materials and various metal powders. An appropriate amount of these fillers is blended with the base resin in accordance with the purpose such as reinforcement of the hub 10 or imparting conductivity.

  By fixing the yoke 12, made of a magnetic material, the rotor magnet 5, and the disk D to the hub portion 10 formed in this way, the sub-assembly of the disk drive device is completed. Hereinafter, the fixing operation of the disk D to the hub portion 10 will be mainly described.

  First, a cylindrical surface 10e formed on the outer periphery of the cylindrical portion 10b is fitted into a hole D2 provided in the center of the disk D, and the lower end surface D1 of the disk D serving as a contact surface is brought into contact with the disk mounting surface 10d. Make contact. Then, from this state, for example, the clamper 13 shown in FIG. 2 is mounted from the inside of the bearing 10 opposite to the bearing, and the clamper 13 is fastened to the shaft 2 with the screw 14, whereby the disk D is connected to the clamper 13 and the hub 10. It is clamped and fixed by receiving the clamping force.

  At the same time, the disk mounting surface 10d of the hub portion 10 receives a pressing force from the lower end surface (contact surface) D1 of the disk D. Thereby, the disk mounting surface 10d is deformed following the lower end surface D1, and the disk mounting surface 10d is corrected by the lower end surface D1 of the disk D. Therefore, even if the dimensional accuracy at the time of molding of the resin hub portion 10 (disc mounting surface 10d) is not so high, the dimensional accuracy of the disc mounting surface 10d becomes the dimensional accuracy of the lower end surface D1 as the disc D is fixed. Can be increased to the same level. Accordingly, the disk D can be fixed on the disk mounting surface 10d in a state where the perpendicularity to the shaft portion 2 is maintained at a high level.

  Further, by forming the region including the disk mounting surface 10d with resin as in this embodiment, the disk mounting surface 10d side can be easily moved against the pressing from the disk D, which is usually formed of aluminum or glass. The disk D can be deformed following the contact surface D1.

  As the lubricating oil filled in the hydrodynamic bearing device 1, various types of lubricating oil can be used, but the lubricating oil provided to the hydrodynamic bearing device for a disk drive device such as an HDD may be used at the time of use or Considering temperature changes during transportation, ester-based lubricating oils excellent in low evaporation rate and low viscosity, such as dioctyl sebacate (DOS), dioctyl azelate (DOZ) and the like can be suitably used.

  In the hydrodynamic bearing device 1 having the above-described configuration, when the shaft portion 2 rotates, the dynamic pressure grooves 8a1 and 8a2 forming regions formed on the inner peripheral surface 8a of the sleeve portion 8 are in contact with the outer peripheral surface 2a of the opposing shaft portion 2. A radial bearing gap is formed between them. As the shaft portion 2 rotates, the lubricating oil in the radial bearing gap is pushed toward the axial center of the dynamic pressure grooves 8a1 and 8a2, and the pressure rises. In this manner, the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft portion 2 in a non-contact manner in the radial direction are configured by the dynamic pressure action of the lubricating oil generated by the dynamic pressure grooves 8a1 and 8a2. .

  At the same time, a thrust bearing gap between the lower end surface 8b of the sleeve portion 8 (region where the dynamic pressure groove 8b1 is formed) and the upper end surface 2b1 of the flange portion 2b facing the lower end surface 8b and the upper end surface 9a of the housing portion 9 are formed. The pressure of the lubricating oil film formed in the thrust bearing gap between the region where the dynamic pressure groove 9a1 is formed and the lower end surface 10a1 of the hub portion 10 opposite to the region is increased by the dynamic pressure action of the dynamic pressure grooves 8b1 and 9a1. The first thrust bearing portion T1 and the second thrust bearing portion T2 that support the rotating member 3 (hub portion 10) in a non-contact manner in the thrust direction are configured by the pressure of these oil films.

  In this case, the disk D rotates while maintaining a high squareness with respect to the shaft portion 2 (rotating shaft), thereby improving the deflection accuracy of the disk D during rotation. Accordingly, it is possible to increase the reading accuracy of the disk D while maintaining the distance between the disk head and the disk head with high accuracy.

  Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and can also be applied to a disk drive device according to another configuration.

  In the above embodiment, the hub portion 10 having the disk mounting surface 10d is formed of resin. However, the disk mounting surface 10d follows the lower end surface (contact surface) D1 of the disk D by pressing from the disk D. As long as it is deformed, the region of the hub portion 10 including at least the disk mounting surface 10d can be formed of another material. Alternatively, the disk mounting surface 10d and its peripheral shape can be appropriately designed so that the disk mounting surface 10d is deformed following the lower end surface D1.

  As a means for introducing the disk D into the disk mounting surface 10d while maintaining a high squareness with respect to the shaft part 2 (rotating shaft), for example, the cylinder of the hub part 10 fitted into the hole D2 of the disk D Various means such as a means for increasing the accuracy of the surface 10e (coaxiality, cylindricity, etc. with respect to the rotation axis) and a means for improving the fixing accuracy of the clamper 13 with respect to the hub portion 10 holding the disk D can be adopted.

  Moreover, in the said embodiment, although the case where the hub part 10 was injection-molded integrally with the shaft part 2 by the injection molding of the resin which uses the metal shaft part 2 as an insert part, for example, only the hub part 10 is formed. After that, the end portion of the shaft portion 2 formed separately from the hub portion 10 can be integrated by being press-fitted into a hole provided in the center of the hub portion 10. Alternatively, the shaft portion 2 can be integrally formed of the same material as the hub portion 10.

  In the above embodiment, the thrust bearing portions T1 and T2 are provided between the upper end surface 2b1 of the flange portion 2b and the lower end surface 8b of the sleeve portion 8 and between the hub portion 10 and the housing portion 9, respectively. As described above, the present invention is applicable regardless of the locations where the thrust bearing portions T1 and T2 are formed. That is, it does not matter whether or not the lower end surface 10a1 of the hub portion 10 forms a thrust bearing gap. For example, although illustration is omitted, both the thrust bearing portions T1 and T2 have both end surfaces of the flange portion 2b and these surfaces. It may be formed between the surface and the opposite surface.

  Further, the components of the hydrodynamic bearing device 1 excluding the hub portion 10 and the shaft portion 2 need not be limited to the above embodiment. For example, although not shown in the drawings, the present invention is also applied to those in which the housing part 9 and the sleeve part 8 are integrally formed of the same material (the bearing member 7 is made into a single product) so as to be integrated between the respective components. Can be applied.

  In the above embodiment, the radial bearing portions R1 and R2 and the thrust bearing portions T1 and T2 are exemplified by the configuration in which the dynamic pressure action of the lubricating oil is generated by the dynamic pressure grooves having a herringbone shape or a spiral shape. However, the present invention is not limited to this.

  For example, although not shown as radial bearing portions R1 and R2, a so-called step-like dynamic pressure generating portion in which axial grooves are formed at a plurality of locations in the circumferential direction, or a plurality of circular arc surfaces in the circumferential direction. A so-called multi-arc bearing in which wedge-shaped radial gaps (bearing gaps) are formed between the opposed shaft portions 2 and the perfect circular outer peripheral surface 2a may be employed.

  In addition, one or both of the first thrust bearing portion T1 and the second thrust bearing portion T2 are also omitted in the drawing, but the region where the dynamic pressure generating portion is formed (for example, the lower end surface 8b of the sleeve portion 8 and the housing portion 9). Is formed of a so-called step bearing or corrugated bearing (in which the step shape is a corrugated shape) in which a plurality of radial groove-shaped dynamic pressure grooves are provided at predetermined intervals in the circumferential direction. You can also.

  In the above embodiment, the radial dynamic pressure generating portion (dynamic pressure grooves 8a1 and 8a2) is provided on the sleeve portion 8 side, and the thrust dynamic pressure generating portion (dynamic pressure groove is provided on the sleeve portion 8 and housing portion 9 side. 8b1) has been described. The regions where the dynamic pressure generating portions are formed are, for example, the outer peripheral surface 2a of the shaft portion 2 and the upper end surface 2b1 of the flange portion 2b, or the hub portion 10 opposed thereto. It can also be provided on the lower end surface 10a1 side.

  In the above embodiment, the disk D mounted on the disk mounting surface 10d is exemplified by a magnetic disk used in, for example, an HDD, but other than this, a CD-ROM, CD-R / RW, DVD- An optical disk such as a ROM / RAM or a magneto-optical disk such as MD or MO is applicable.

  Further, in the above description, the lubricating oil is exemplified as the fluid that fills the inside of the hydrodynamic bearing device 1 and causes the hydrodynamic action in the radial bearing gap or the thrust bearing gap. A fluid capable of generating a dynamic pressure action, for example, a gas such as air, a fluid lubricant such as a magnetic fluid, or lubricating grease may be used.

1 is a cross-sectional view of a disk drive device according to an embodiment of the present invention. It is sectional drawing of the hydrodynamic bearing apparatus which comprises a disk drive device. It is a longitudinal cross-sectional view of a sleeve part. It is the lower end surface of a sleeve part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing apparatus 2 Shaft part 3 Rotating member 4 Stator coil 5 Rotor magnet 7 Bearing member 8 Sleeve part 8a1, 8a2, 8b1 Dynamic pressure groove 9 Housing part 10 Hub part 10a Disk part 10b Cylindrical part 10c Eave part 10d Disk mounting Surface 12 Yoke 13 Clamper 14 Screw D Disk D1 Lower end surface (contact surface)
S Seal space R1, R2 Radial bearing part T1, T2 Thrust bearing part

Claims (2)

A rotating member having a shaft portion and a hub portion integrally or separately provided on the shaft portion, and the dynamic pressure action of fluid generated in a radial bearing gap facing the outer peripheral surface of the shaft portion rotates the rotating member in the radial direction. A hydrodynamic bearing device including a radial bearing portion that freely supports non-contact;
A disk that contacts the disk mounting surface of the hub portion and is fixed by a predetermined clamping force;
In a disk drive device comprising a motor unit that rotationally drives the rotating member on which the disk is mounted,
The disk drive device according to claim 1, wherein the disk mounting surface is deformed following the contact surface of the disk by the clamping force.   The disk drive device according to claim 1, wherein an area including the disk mounting surface is formed of a resin.

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