JP2008305471A - Spindle motor for driving disk, and disk driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spindle motor for driving a disk, and a disk driving device in which a manufacturing cost can be lowered while productivity can be improved. <P>SOLUTION: The material of a disk supporting member 43 of a spindle motor 1 is thermoplastic resin having lower cutting resistance than a metal material constituting a hub member 42. Therefore, highly accurate finish working can be performed for the disk supporting member 43 suppressing damage of cutlery due to cutting resistance also in a short time. Thereby, the manufacturing cost of the spindle motor 1 can be reduced, also, productivity of the spindle motor 1 can be improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a disk drive spindle motor and a disk drive apparatus for rotating a disk such as a magnetic disk or an optical disk around a predetermined central axis.

  A hard disk device used for a personal computer, car navigation, or the like is equipped with a spindle motor that rotates a magnetic disk around its central axis. FIG. 5 is a longitudinal sectional view showing a configuration example of a conventional spindle motor. As shown in FIG. 5, the conventional spindle motor 9 includes a stator portion 91 having a stator core 911 and a coil 912, and a rotor portion 92 having a rotor magnet 921. The spindle motor 9 generates torque by the action of magnetic flux between the stator core 911 and the rotor magnet 921, and rotates the rotor portion 92 around the central axis L.

  The rotor portion 92 of the spindle motor 9 includes a shaft 922 provided along the central axis L, and a hub member 923 that is fixed to the shaft 922 and extends around the central axis L. The hub member 923 has support surfaces 923 a and 923 b for supporting the magnetic disk 93. The spindle motor 9 supports the magnetic disk 93 in a state where the lower surface and the inner peripheral end surface of the magnetic disk 93 are in contact with the support surfaces 923a and 923b, respectively, and the shaft 922 and the hub member 923 are integrated around the central axis L. By rotating, the magnetic disk 93 is rotated.

  Such a conventional spindle motor is disclosed in Patent Document 1, for example.

International Publication No. 02/004825 Pamphlet

  The hub member 923 of the conventional spindle motor 9 has been obtained by cutting a metal material such as aluminum or stainless steel with high accuracy. However, if the entire shape of the hub member 923 is formed by cutting, the hub member 923 has a high processing cost, which hinders inexpensive manufacture of the spindle motor. Further, conventionally, since a metal material having a high cutting resistance has been cut, the cutting blade is worn quickly, and it has been difficult to shorten the processing time. This has further increased the manufacturing cost of the spindle motor and has been a factor of deteriorating productivity.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a disk drive spindle motor and a disk drive apparatus that can reduce manufacturing costs and improve productivity. .

  The disk drive spindle motor according to claim 1 is a disk drive spindle motor that mounts a disk having a hole in the center and rotates the disk around a predetermined center axis, wherein the fixed part and the center shaft A hub member extending radially in the periphery, a bearing mechanism that supports the hub member rotatably relative to the fixed portion, and a disc that is fixed relative to the hub member and supports the disc A support member, and the disc support member is disposed so as to surround the central axis, and contacts a main surface on one axial side of the disc, and extends from the base in the axial direction and extends the central axis. A positioning portion that surrounds and is in contact with an inner peripheral surface or an inner peripheral edge of the hole of the disc, and the disc support member includes the hub member. Than the material formed, characterized in that the cutting resistance and a small material.

  In the spindle motor for driving a disk according to claim 2, the hub member has a cylindrical portion positioned radially inward of the positioning portion, and the positioning portion is spaced from the cylindrical portion via a gap in the radial direction. It is characterized by facing.

  The disk drive spindle motor according to claim 3 is characterized in that the base portion and the positioning portion are made of a resin material.

  The disk drive spindle motor according to claim 4 is characterized in that the resin material does not substantially contain a filler.

  In the disk drive spindle motor according to claim 5, the base is joined to the hub member at a portion opposite to a portion contacting the main surface of the disc, and the positioning portion is formed on the base portion. It is characterized in that it is located on the radially inner side of the portion joined to the hub member.

  The disk drive spindle motor according to claim 6 is characterized in that the base portion is joined to the hub member by heat welding.

  In the disk drive spindle motor according to claim 7, the portion of the base that contacts the disk main surface continuously makes a round around the central axis in the circumferential direction, and the disk inner peripheral surface of the positioning portion or The portion that contacts the inner peripheral edge makes one round of the central axis continuously in the circumferential direction.

  The spindle motor for driving a disk according to an eighth aspect is characterized in that the hub member is obtained by press-molding a metal material.

  A disk drive device according to a ninth aspect includes a housing, a spindle motor for driving the disk according to any one of claims 1 to 8 which is fixed inside the housing and rotates the disk, and information on a required position of the disk. And an access unit for writing or reading.

  According to invention of Claims 1-9, the disk support member is comprised from the material whose cutting resistance is smaller than the material which comprises a hub member. For this reason, it is possible to perform highly accurate finish cutting on the support surface of the disk in a short time while suppressing damage to the blade due to cutting resistance. Thereby, the manufacturing cost of the spindle motor can be reduced, and the productivity of the spindle motor can be improved.

  In particular, according to the second aspect of the present invention, the positioning portion of the disk support member faces the cylindrical portion of the hub member in the radial direction with a gap therebetween. For this reason, the deformation | transformation by the thermal expansion of a positioning part can be escaped to radial direction.

  In particular, according to the third aspect of the present invention, the base portion and the positioning portion of the disk support member are made of a resin material. For this reason, a disk support member can be obtained at low cost. Further, the cutting resistance of the disk support member can be reduced as compared with the case where a soluble material or a metal material is used.

  Particularly, according to the invention described in claim 4, the resin material does not substantially contain a filler. For this reason, generation | occurrence | production of the foreign material resulting from a filler can be suppressed.

  In particular, according to the fifth aspect of the present invention, the base portion of the disc support member is joined to the hub member at a portion opposite to the portion that contacts the main surface of the disc, and the positioning portion is attached to the hub member. It is located radially inward from the part to be joined. For this reason, the disk support member makes good contact with the main surface of the disk and the inner peripheral surface or the inner peripheral edge, and can support the disk stably. Further, it is possible to prevent the positioning portion from being affected by the joining of the disk support member and the hub member. Moreover, the displacement amount to the radial direction outer side by the thermal expansion of a positioning part can be suppressed.

  In particular, according to the invention described in claim 6, the base is joined to the hub member by heat welding. For this reason, the base is easily and firmly joined to the hub member.

  In particular, according to the seventh aspect of the present invention, the portions of the base portion and the positioning portion that are in contact with the disk continuously make a round around the central axis in the circumferential direction. For this reason, a disk can be supported stably.

  In particular, according to the invention described in claim 8, the hub member is obtained by press-molding a metal material. For this reason, the hub member can be obtained at low cost, and the manufacturing cost of the spindle motor can be further reduced.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, for convenience of explanation, terms such as “upper”, “lower”, “upper surface”, and “lower surface” are used in the vertical direction in FIGS. 1 and 2. However, this does not limit the installation posture of the disk drive device and the disk drive spindle motor of the present invention.

<1. Configuration of disk drive>
FIG. 1 is a longitudinal sectional view of a disk drive device 2 including a disk drive spindle motor 1 according to an embodiment of the present invention. The disk drive device 2 is a hard disk device that reads and writes information while rotating the disk 21. As shown in FIG. 1, the disk drive device 2 mainly includes a disk 21, a spindle motor 1, an access unit 22, and a housing 23. The disk 21 is a disk-shaped information recording medium having a hole in the center. The spindle motor 1 holds and rotates the disk 21. The access unit 22 reads and writes information from and to the disk 21. The housing 23 accommodates the disk 21, the spindle motor 1, and the access unit 22 in the internal space 233 and isolates them from the outside of the housing 23.

  The housing 23 includes a cup-shaped first housing member 231 and a plate-shaped second housing member 232. The first housing member 231 has an opening at the top. The spindle motor 1 and the access unit 22 are installed on the bottom surface inside the first housing member 231. The second housing member 232 is joined to the first housing member so as to cover the upper opening of the first housing member 231, thereby forming an internal space 233 of the housing 23. The internal space 233 of the housing 23 is a clean space with extremely little dust.

  The disk 21 is mounted on a disk support member 43 of the spindle motor 1 and is fixed to the spindle motor 1 by a clamper 44 and a ring wire 45. The access unit 22 includes a head 221, an arm 222, and a head moving mechanism 223. The head 221 is close to the main surface of the disk 21 and magnetically reads and writes information from and to the disk 21. The arm 222 swings along the main surface of the disk 21 while supporting the head 221. The head moving mechanism 223 is installed on the side of the disk 21. The head moving mechanism 223 moves the head 221 relative to the disk 21 and the spindle motor 1 by swinging the arm 222. As a result, the head 221 accesses a required position of the disk 21 in the state of being close to the main surface of the rotating disk 21, and reads and writes information.

<2. Spindle motor configuration>
Next, a detailed configuration of the spindle motor 1 will be described. FIG. 2 is a longitudinal sectional view of the spindle motor 1. FIG. 3 is a top view of the hub member 42 and the disk support member 43 that are components of the spindle motor 1. The spindle motor 1 mainly includes a stator portion 3 fixed to the housing 23 of the disk drive device 2 and a rotor portion 4 for mounting the disk 21 and rotating it around a predetermined central axis L.

  The stator unit 3 includes a fixed frame 31, a bearing sleeve 32, a stator core 33, and a coil 34.

  The fixed frame 31 is formed of a metal material such as aluminum and is fixed to the housing 23 of the disk drive device 2 by screwing or the like. The fixed frame 31 is formed with a substantially cylindrical bearing holder 311 protruding in the axial direction (a direction along the central axis L; the same applies hereinafter) around the central axis L. The inner peripheral side of the bearing holder 311 (the inner peripheral side with respect to the central axis L. The same applies hereinafter) is a through hole 312 for holding the bearing sleeve 32. Further, the outer peripheral side of the bearing holder 311 (the outer peripheral side with respect to the central axis L; the same applies hereinafter) is an attachment surface on which the stator core 33 is fitted.

  Note that the fixed frame 31 and the first housing member 231 may be formed of a single member. In this case, the first housing member 231 also includes a bearing holder 311.

  The bearing sleeve 32 is a substantially cylindrical fixed bearing member for holding a shaft 41 (to be described later) relatively rotatably with respect to the stator portion 3. The bearing sleeve 32 is inserted into the through hole 312 of the bearing holder 311 and is fixed to the bearing holder 311 by press-fitting or shrink fitting. A through hole 321 through which the shaft 41 is inserted is formed on the inner peripheral side of the bearing sleeve 32. A herringbone-shaped groove (not shown) for generating dynamic pressure in the lubricating oil filled between the outer peripheral surface of the shaft 41 and the inner peripheral surface of the bearing sleeve 32 is formed on the inner peripheral surface of the bearing sleeve 32. ) Is engraved.

  The stator core 33 has a yoke portion 331 fitted to the outer peripheral surface of the bearing holder 311 and a plurality of stator cores 33 that protrude from the yoke portion 331 toward the outside in the radial direction (the radial direction with respect to the central axis L; the same applies hereinafter). And a tooth portion 332. The stator core 33 is formed of, for example, a laminated steel plate in which electromagnetic steel plates are laminated in the axial direction.

  The coil 34 is wound around each tooth portion 332 of the stator core 33. The coil 34 is connected to a power supply device (not shown). When a drive current is applied to the coil 34 from the power supply device, a radial magnetic flux is generated in the tooth portion 332. The magnetic flux generated in the tooth portion 332 interacts with the magnetic flux of a rotor magnet 46 described later, and generates torque for rotating the rotor portion 4 around the central axis L.

  On the other hand, the rotor unit 4 includes a shaft 41, a hub member 42, a disk support member 43, a clamper 44, a ring wire 45, and a rotor magnet 46.

  The shaft 41 is a substantially columnar member provided along the central axis L. The shaft 41 is inserted through the through hole 321 of the bearing sleeve 32. The outer peripheral surface of the shaft 41 and the inner peripheral surface of the bearing sleeve 32 face each other with a minute gap (for example, about several μm), and the gap is filled with lubricating oil. For this reason, the shaft 41 can rotate around the central axis L while being held in the through hole 321. When the shaft 41 rotates, the lubricating oil is pressurized by a herringbone-shaped groove formed on the inner peripheral surface of the bearing sleeve 32. For this reason, the shaft 41 rotates while slightly floating due to the dynamic pressure of the lubricating oil.

  The hub member 42 is a member that is fixed to the shaft 41 and rotates together with the shaft 41. The hub member 42 has a shape that expands in the radial direction around the central axis L. More specifically, the hub member 42 includes a flat plate portion 421 that extends along a plane orthogonal to the central axis L, and a first cylindrical portion 422 that protrudes upward from an inner peripheral edge of the flat plate portion 421. And a second cylindrical portion 423 that hangs down from the outer edge of the flat plate portion 421. In addition, a cylindrical joint portion 424 that is joined to the shaft 41 by press-fitting or shrink fitting is further formed on the inner peripheral side of the first cylindrical portion 422.

  The hub member 42 is obtained by press-molding a metal material such as aluminum, magnetic SUS (stainless steel), cold-rolled steel plate (for example, SPCC, SPCD, SPCE) into the above shape. For this reason, the hub member 42 can be obtained at a lower cost than the hub member obtained by cutting. The surface of the hub member 42 is plated with nickel in order to prevent damage such as rust. The flat plate portion 421 of the hub member 42 is formed with a plurality of through holes 421a into which the leg portions 433 of the disc support member 43 are inserted.

  The disk support member 43 is a member for supporting the disk 21 on the upper surface side of the hub member 42. The disk support member 43 includes a base portion 431 that is fixed to the flat plate portion 421 of the hub member 42, and a positioning portion 432 that protrudes in the axial direction from the inner peripheral edge of the base portion 431. The base portion 431 and the positioning portion 432 are both arranged in an annular shape so as to surround the central axis L. When the disk 21 is supported on the disk support member 43, the lower surface (the main surface on one side in the axial direction) of the disk 21 comes into contact with the upper surface 431a of the base 431, and the axial position of the disk 21 is restricted. When the outer peripheral surface of the positioning portion 431 contacts the inner peripheral surface or the inner peripheral edge of the disc 21, the position of the disc 21 in the plane perpendicular to the central axis L is regulated. Both the upper surface 431a of the base portion 431 and the outer peripheral surface of the positioning portion 431 continuously make a round around the central axis L in the circumferential direction. For this reason, the disk support member 43 can stably support the disk 21.

  Further, the disk support member 43 has leg portions 433 that protrude in the axial direction from the lower surface of the base portion 431. The disk support member 43 is formed by inserting a plurality of leg portions 433 into the plurality of through holes 421a of the hub member 42 and thermally welding the tips of the leg portions 433 protruding from the lower surface side of the hub member 42 to the flat plate portion 421. The hub member 42 is joined. The base portion 431, the positioning portion 432, and the leg portion 433 are obtained as a single member by injection molding a thermoplastic resin such as polyacetal or nylon.

  The surface of the disk support member 43 that contacts the disk 21, that is, the upper surface 431 a of the base portion 431 and the outer peripheral surface 432 a of the positioning portion 432 are cutting surfaces that are finished with high precision by cutting. For this reason, the disk 21 can be rotated with high rotational accuracy. The disk support member 43 is made of a thermoplastic resin having a cutting resistance lower than that of the metal material constituting the hub member 42. For this reason, high-precision finishing can be performed on the disk support member 43 in a short time while suppressing damage to the blade due to cutting resistance. Thereby, the manufacturing cost of the spindle motor 1 can be reduced, and the productivity of the spindle motor 1 can be improved.

  The disk support member 43 is made of a thermoplastic resin such as polyacetal or nylon. A part made of this resin exhibits a smaller cutting resistance when turning under the same conditions as compared to turning a part made of a metal material constituting the hub member 42. For this reason, high-precision finishing can be performed on the disk support member 43 in a short time while suppressing damage to the cutting tool due to cutting.

  Further, the resin material such as polyacetal and nylon constituting the disk support member 43 does not substantially contain a filler. In a normal resin material, in order to improve the characteristics of the material, a powder called filler or fiber may be added to the base resin. However, when a resin material containing a filler is cut, the filler is exposed on the cut surface and may be peeled off in some cases. The filler that has been peeled off becomes a foreign matter that is not preferable for the hard disk drive. Whether or not the filler is peeled off is affected by the type of resin used as the base, the added filler, and the addition method, and therefore the resin material containing the filler is not necessarily usable as the material of the disk support member 43. However, when a problem caused by the filler occurs, the use of a resin material without a filler should be considered.

  The material constituting the disk support member 43 is not limited to the thermoplastic resin. Any material can be used as long as the cutting resistance is smaller than that of a normal metal material and a smooth cutting surface can be obtained. For example, the hub member 42 may be made of austenitic stainless steel, and the disk support member 43 may be made of brass having excellent machinability. Moreover, even when using a thermoplastic resin, it is not limited to polyacetal or nylon. Engineering plastics such as liquid crystal polymers can be widely used.

  Further, the disk support member 43 is a separate member from the hub member 42 as described above. For this reason, the hub member 42 and the disk support member 43 can be obtained at low cost by using suitable materials.

  2 and 3, the positioning portion 432 of the disk support member 43 faces the first cylindrical portion 422 of the hub member 42 in the radial direction with a gap therebetween. For this reason, even when the positioning portion 432 expands due to heat generation during operation or an increase in ambient environmental temperature, the deformation can be released radially inward.

  FIG. 4 is a longitudinal cross-sectional view showing the state in which the disc support member is deformed due to thermal expansion, with a slight exaggeration. In FIG. 4, the disk support member 43 before expansion is indicated by a temporary line, and the disk support member 43 after expansion is indicated by a solid line. Since the disk support member 43 is made of a thermoplastic resin having a higher linear expansion coefficient than the hub member 42 and the disk 21, it tends to expand larger than the hub member 42 and the disk 21 when the temperature rises. However, the positioning portion 432 of the disk support member 43 is separated from the first cylindrical portion 422 of the hub member 42. For this reason, the positioning part 432 can be bent slightly inward in the radial direction. As a result, the pressure applied from the positioning portion 432 to the disk 21 is reduced, and deformation of the disk 21 is suppressed.

  Further, the outer peripheral surface 432 a of the positioning portion 432 is located on the radially inner side of the leg portion 433 joined to the hub member 42. For this reason, the influence on the positioning part 432 by the joining with the hub member 42 can be prevented. In addition, since the leg portion 433 positioned radially outward from the positioning portion 432 is fixed to the hub member 42, the amount of displacement of the positioning portion 432 outward in the radial direction due to thermal expansion is further suppressed.

  The hub member 42 is preferably made of a material having the same or approximate linear expansion coefficient as the main material constituting the disk 21. For example, when the main material constituting the disk 21 is aluminum, the hub member 42 is preferably made of aluminum. When the main material constituting the disk 21 is glass, the hub member 42 is preferably made of stainless steel having a linear expansion coefficient close to that of the glass. In this way, the expansion coefficient of the hub member 42 and the expansion coefficient of the disk 21 when the temperature rises can be made substantially coincident. Thereby, the pressure applied to the disk 21 can be further reduced.

  Returning to FIG. The clamper 44 contacts the upper surface of the disk 21 supported on the disk support member 43, and fixes the disk 21 on the disk support member 43. The clamper 44 is connected to the first cylindrical portion 422 of the hub member 42 via the ring wire 45. The clamper 44 presses the upper surface of the disk 21 by the elastic force of the ring wire 45. Both the clamper 44 and the ring wire 45 are made of a conductive metal material. For this reason, the clamper 44 and the ring wire 45 can release electricity from the disk 21 to the hub member 42. Thereby, charging of the disk 21 is prevented.

  The rotor magnet 46 is fixed to the inner peripheral surface of the second cylindrical portion 423 of the hub member 42. The rotor magnet 46 is arranged in an annular shape so as to surround the central axis L. The inner peripheral surface of the rotor magnet 46 is a magnetic pole surface and faces the outer peripheral surface of the plurality of teeth portions 332 of the stator core 33.

  In such a spindle motor 1, when a drive current is applied to the coil 34 of the stator portion 3, a radial magnetic flux is generated in the plurality of teeth portions 332 of the stator core 33. Torque is generated by the action of magnetic flux between the tooth portion 332 and the rotor magnet 46, and the rotor portion 4 rotates around the central axis L with respect to the stator portion 3. The disk 21 supported on the disk support member 43 rotates around the central axis L together with the shaft 41, the hub member 42, and the disk support member 43.

<3. Modification>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to said example. For example, the above spindle motor 1 is for rotating the magnetic disk 21, but the disk driving spindle motor of the present invention may be for rotating other recording disks such as an optical disk. Good. Further, the disk drive device 2 described above is a hard disk device including the disk 21 as a component, but the disk drive device of the present invention does not necessarily include a disk as a component. For example, the disk drive apparatus of the present invention may be an optical disk apparatus in which an optical disk such as a CD-ROM, CD-R, CD-RW, DVD-ROM or the like is mounted when used.

It is a longitudinal cross-sectional view of a disk drive device. It is a longitudinal cross-sectional view of a spindle motor It is a top view of a hub member and a disk support member. It is the longitudinal cross-sectional view which showed a mode that a disk support member deform | transforms by thermal expansion. It is the longitudinal cross-sectional view which showed the structural example of the conventional spindle motor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spindle motor 2 Disk drive device 3 Stator part 4 Rotor part 21 Disk 22 Access part 23 Housing 31 Fixed frame 32 Bearing sleeve 33 Stator core 34 Coil 41 Shaft 42 Hub member 43 Disk support member 44 Clamper 45 Ring wire 46 Rotor magnet 431 Base part 432 Positioning part 433 Leg L Center axis

Claims (9)

A spindle motor for driving a disk, which is equipped with a disk having a hole in the center and rotates the disk around a predetermined center axis,
A fixed part;
A hub member extending radially around the central axis;
A bearing mechanism that rotatably supports the hub member relative to the fixed portion;
A disk support member fixed relative to the hub member and supporting the disk;
The disk support member is
A base that surrounds the central axis and contacts a main surface on one axial side of the disk;
A positioning portion extending in the axial direction from the base portion and surrounding the central axis and contacting an inner peripheral surface or an inner peripheral edge of the hole of the disc, and the disc support member includes the hub member. A spindle motor for driving a disk, characterized in that it is made of a material having a cutting resistance smaller than that of the constituent material. The hub member has a cylindrical portion located radially inward of the positioning portion,
The disk drive spindle motor according to claim 1, wherein the positioning portion faces the cylindrical portion via a gap in a radial direction.   3. The disk drive spindle motor according to claim 1, wherein the base portion and the positioning portion are made of a resin material.   4. The disk drive spindle motor according to claim 3, wherein the resin material contains substantially no filler. The base is joined to the hub member at a portion opposite to the portion that contacts the main surface of the disc,
5. The disk drive spindle motor according to claim 1, wherein the positioning portion is located radially inward of a portion of the base portion joined to the hub member.   6. The disk drive spindle motor according to claim 5, wherein the base is joined to the hub member by thermal welding. The portion of the base that comes into contact with the disk main surface continuously makes a round around the central axis in the circumferential direction,
7. The disk drive according to claim 1, wherein a portion of the positioning portion that contacts the inner peripheral surface or the inner peripheral edge of the positioning portion makes a round around the central axis continuously in the circumferential direction. Spindle motor.   The disk drive spindle motor according to any one of claims 1 to 7, wherein the hub member is obtained by press molding a metal material. A disk drive for rotating the disk,
A housing;
The disk drive spindle motor according to any one of claims 1 to 8, wherein the disk is fixed inside the housing and rotates the disk.
A disk drive device comprising: an access unit for writing or reading information at a required position of the disk.

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