JP2011024351A - Spindle motor, disk drive, and manufacturing method for spindle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bearing device in which an adhesive is interposed uniformly in an annual gap between a cylindrical portion of a hub and a magnetic member so that the presence of the adhesive prevents the distortion of the hub. <P>SOLUTION: A spindle motor 902 includes a stationary portion 903 and a rotating portion 904 supported rotatably relative to the stationary portion 903. The rotating portion 904 has a hub 942 having a disc portion 951 expanding radially relative to a vertically extending axis and a cylindrical portion 952 extending down from the outer edge of the disc portion 951, a magnetic member 943 fixed to the inner peripheral surface of the cylindrical portion 952 via an adhesive 961, an annual gap 970 including a radial gap between the inner peripheral surface of the cylindrical portion 952 and the outer peripheral surface of the magnetic member 943, and an annual lower opening 980 communicating with the lower end of the annual gap 970 and having a gap larger radially than the radial gap, the annual gap 970 and the annual lower opening 980 being formed between the hub 942 and the magnetic member 943. The volume of the annual lower opening 980 is equal to or larger than that of the annual gap 970. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a spindle motor, a disk drive device, and a spindle motor manufacturing method.

  A hard disk device or an optical disk device is equipped with a spindle motor for rotating the disk around its central axis. The spindle motor has a stationary part fixed to the housing of the apparatus and a rotating part that rotates while supporting the disk. The spindle motor generates torque about the central axis by the magnetic flux generated between the stationary part and the rotating part, and thereby rotates the rotating part with respect to the stationary part.

For example, Japanese Patent Application Laid-Open No. 2006-331558 describes a spindle motor in which a stator is fixed to a base, a rotor yoke and a rotor magnet are fixed to a rotor hub, and driven to rotate by the interaction between a magnetic field generated from the stator and the rotor magnet. Has been.
JP 2006-331558 A

  Paragraph 0030 of JP-A-2006-331558 describes that the rotor yoke is fixed to the inner peripheral surface of the cylindrical portion of the rotor hub with an adhesive. However, for example, when an adhesive is applied to the inner peripheral surface of the cylindrical portion of the rotor hub and then the rotor yoke is inserted and fixed, the adhesive is uniformly distributed over the entire circumference between the rotor hub and the rotor yoke. It is difficult. If the distribution of the adhesive is not uniform, the rotor hub is likely to be distorted as the adhesive is cured. Although such distortion is generally within the allowable range at the quality level required for a spindle motor, it is desirable to prevent the occurrence of distortion in the rotor hub in order to obtain a higher quality spindle motor. Yes.

  An object of the present invention is to provide a bearing device capable of uniformly interposing an adhesive in an annular gap between a cylindrical portion of a hub and a magnetic member, thereby preventing distortion of the hub.

  1st invention of this application is provided with the stationary part and the rotating part supported rotatably with respect to the said stationary part, The said rotating part is a disk part which spreads to radial direction with respect to the central axis extended in an up-down direction. And a hub having a cylindrical portion extending downward from an outer edge portion of the disk portion, and a magnetic member fixed to the inner peripheral surface of the cylindrical portion via an adhesive, and the hub and the magnetic member An annular gap including a radial gap between the inner circumferential surface of the cylindrical portion and the outer circumferential surface of the magnetic member, and a radial gap from the radial gap in communication with a lower end portion of the annular gap. The spindle motor has a large annular lower opening, and the volume of the annular lower opening is equal to or larger than the volume of the annular gap.

  The second invention of the present application is bonded to a hub having a disk part extending in a radial direction with respect to a central axis extending vertically and a cylindrical part extending downward from an outer edge part of the disk part, and an inner peripheral surface of the cylindrical part A method of manufacturing a spindle motor having a magnetic member fixed through an agent, wherein: a) a step of fitting and inserting the magnetic member into a radially inner side of the cylindrical portion of the hub; and b) the step a) the fitting insertion of a) is completed, and an annular gap including a radial gap between an inner circumferential surface of the cylindrical portion and an outer circumferential surface of the magnetic member between the hub and the magnetic member; A step of forming an annular lower opening communicating with the lower end of the gap and having a radial interval larger than the radial gap and having a volume equal to or larger than the volume of the annular gap; c) Supplying an adhesive to the annular lower opening after step b); ) After step c), a method for manufacturing a spindle motor and a step of heating the adhesive.

  According to the first invention of the present application, in the manufacturing process of the spindle motor, the adhesive can be supplied to the annular lower opening, and the supplied adhesive can penetrate into the annular gap. Since the adhesive can be supplied to the annular lower opening at a time, it is possible to prevent air bubbles from being mixed into the adhesive. Thereby, an adhesive agent can be uniformly interposed in the annular gap, and distortion of the hub can be prevented.

  According to the second invention of the present application, an adhesive can be supplied to the annular lower opening, and the supplied adhesive can penetrate into the annular gap. Since the adhesive can be supplied to the annular lower opening at a time, it is possible to prevent air bubbles from being mixed into the adhesive. Thereby, an adhesive agent can be uniformly interposed in the annular gap, and distortion of the hub can be prevented. Further, by heating the adhesive, the viscosity of the adhesive can be lowered and the penetration of the adhesive into the annular gap can be promoted.

FIG. 1 is a partial longitudinal sectional view of a spindle motor. FIG. 2 is a longitudinal sectional view of the disk drive device. FIG. 3 is a longitudinal sectional view of the spindle motor. FIG. 4 is an enlarged longitudinal sectional view of the cylindrical portion of the magnetic member holding portion, the yoke, the rotor magnet, and the vicinity thereof. FIG. 5 is a longitudinal sectional view showing the vicinity of the annular gap and the annular lower opening further enlarged than FIG. 4. FIG. 6 is a flowchart showing a procedure for fixing the hub and the yoke. FIG. 7 is a diagram showing how the yoke is fitted and inserted into the hub. FIG. 8 is a diagram illustrating a state in which an adhesive is supplied to the annular lower opening. FIG. 9 is a diagram showing how the adhesive penetrates into the annular gap.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In the following, the shape and positional relationship of each member will be described with the direction along the central axis 9 as the vertical direction and the direction in which the cylindrical portion extends from the outer edge of the disc portion of the hub as the downward direction. However, this is defined only in the vertical direction for convenience of explanation, and the installation posture when the bearing device, the spindle motor, and the disk drive device according to the present invention are mounted on an actual device. It is not limited.

<1. Spindle motor according to one embodiment>
FIG. 1 is a partial longitudinal sectional view of a spindle motor 902 according to an embodiment of the present invention. As shown in FIG. 1, the spindle motor 902 includes a stationary part 903 and a rotating part 904. The rotating unit 904 is supported rotatably with respect to the stationary unit 903.

  The rotating unit 904 includes a hub 942 and a magnetic member 943. The hub 942 includes a disc portion 951 and a cylindrical portion 952. The disc portion 951 is a portion that extends in the radial direction with respect to the central axis extending in the vertical direction. The cylindrical portion 952 is a portion extending downward from the outer edge portion of the disc portion 951. The magnetic member 943 is fixed to the inner peripheral surface of the cylindrical portion 952 with an adhesive 961.

  An annular gap 970 and an annular lower opening 980 are provided between the hub 942 and the magnetic member 943. The annular gap 970 is a space including a radial gap between the inner circumferential surface of the cylindrical portion 952 and the outer circumferential surface of the magnetic member 943. The annular lower opening 980 is a space that communicates with the lower end of the annular gap 970 and has a larger radial interval than the radial gap. The volume of the annular lower opening 980 is equal to or larger than the volume of the annular gap 970.

  In the manufacturing process of the spindle motor 902, first, the magnetic member 943 is fitted and inserted inside the cylindrical portion 952 of the hub 942 in the radial direction. When the fitting insertion of the magnetic member 943 into the hub 942 is completed, an annular gap 970 and an annular lower opening 980 are formed between the hub 942 and the magnetic member 943. Subsequently, an adhesive 961 is supplied to the annular lower opening 980. Thereafter, the adhesive 961 is heated.

  The adhesive 961 supplied to the annular lower opening 980 gradually penetrates into the annular gap 970 by capillary force. As described above, the volume of the annular lower opening 980 is equal to or larger than the volume of the annular gap 970. For this reason, the adhesive 961 interposed in the annular gap 970 can be supplied to the annular lower opening 980 at a time. Therefore, bubbles can be prevented from being mixed into the adhesive 961. Thereby, the adhesive 961 can be uniformly permeated into the annular gap 970. As a result, the distortion of the hub 942 that occurs when the adhesive 961 is cured can be suppressed.

<2. More specific embodiment>
<2-1. Configuration of disk drive>
Subsequently, a more specific embodiment of the present invention will be described.

  FIG. 2 is a longitudinal sectional view of the disk drive device 1. The disk drive device 1 is a device that reads and writes information on the disk 12 while rotating a magnetic disk 12 (hereinafter simply referred to as “disk 12”). As shown in FIG. 2, the disk drive device 1 includes an apparatus housing 11, two disks 12, an access unit 13, and a spindle motor 2.

  The device housing 11 is a housing that accommodates the two disks 12, the access unit 13, and the spindle motor 2. The access unit 13 reads and writes information from and to the disk 12 by moving the head 131 along the recording surface of the disk 12 supported by the spindle motor 2. The access unit 13 may perform only one of reading and writing of information with respect to the disk 12.

<2-2. Spindle motor configuration>
Next, the configuration of the spindle motor 2 will be described. FIG. 3 is a longitudinal sectional view of the spindle motor 2. As shown in FIG. 3, the spindle motor 2 includes a stationary part 3 and a rotating part 4.

  The stationary part 3 includes a base member 31, a stator unit 32, and a stationary bearing unit 33.

  The base member 31 is a part of the device housing 11 (see FIG. 2) of the disk drive device 1 and is formed integrally with other parts of the device housing 11. However, the base member 31 and the device housing 11 may be separate members fixed to each other. The base member 31 includes a flat plate portion 311 extending in a radial direction (a direction orthogonal to the central axis 9; the same applies hereinafter), and a substantially cylindrical holder portion 312 protruding upward from an inner edge portion of the flat plate portion 311. The base member 31 is made of a metal such as an aluminum alloy, for example.

  The stator unit 32 has a stator core 321 and a coil 322. The stator unit 32 has a function of generating magnetic flux according to the drive current applied to the coil 322. The stator core 321 includes a ring-shaped core back 321a and a plurality of teeth portions 321b projecting radially outward from the core back 321a. The core back 321 a is fixed to the outer peripheral surface of the holder portion 312 of the base member 31. The stator core 321 is formed of, for example, a laminated steel plate in which electromagnetic steel plates are laminated in the axial direction (a direction along the central axis 9; the same applies hereinafter). In addition, the coil 322 is configured by a conductive wire wound around each tooth portion 321 b of the stator core 321.

  The stationary bearing unit 33 is a mechanism for rotatably supporting the shaft 41 on the rotating unit 4 side. The stationary bearing unit 33 includes a sleeve 331 and a cap 332. The sleeve 331 is a substantially cylindrical member fixed to the inner peripheral surface of the holder portion 312 of the base member 31. The cap 332 is a member that closes the lower opening of the sleeve 331. The inner peripheral surface of the sleeve 331 and the outer peripheral surface of the shaft 41 oppose each other in the radial direction. The gap between the inner peripheral surface of the sleeve 331 and the outer peripheral surface of the shaft 41 is filled with lubricating oil.

  The rotating unit 4 includes a shaft 41, a hub 42, a yoke 43, and a rotor magnet 44.

  The shaft 41 is a substantially cylindrical member that extends in the vertical direction along the central axis 9. The shaft 41 is rotatably supported with respect to the stationary bearing unit 33 while being inserted inside the sleeve 331. An annular flange 411 is formed at the lower end of the shaft 41. The collar portion 411 is located between the lower surface of the sleeve 331 and the upper surface of the cap 332. The collar portion 411 plays a role of preventing the shaft 41 from coming out of the sleeve 331.

  The hub 42 is a member that is fixed to the shaft 41 and rotates together with the shaft 41. The hub 42 includes a bush 421 that is fixed to the upper end portion of the shaft 41 and a magnetic member holding portion 422 that is fixed to the outer peripheral surface of the bush 421. The magnetic member holding part 422 includes a disk part 51, a cylindrical part 52, and a flange part 53. The disc portion 51 is a portion that is fixed to the bush 421 and expands outward in the radial direction. The cylindrical portion 52 is a portion extending downward from the outer edge portion of the disc portion 51. Further, the flange portion 53 is a portion that protrudes radially outward from the lower end portion of the cylindrical portion 52.

  The outer peripheral surface of the cylindrical portion 52 serves as a contact surface that contacts the inner peripheral portions of the two disks 12. Further, the upper surface of the flange portion 53 is a mounting surface on which the lower disk 12 is mounted. The lower disk 12 is placed on the upper surface of the flange portion 53, and the upper disk 12 is placed on the upper part via a spacer 121. Thus, the cylindrical portion 52 and the flange portion 53 are support portions that support the two disks 12.

  The disk 12 of this embodiment is formed of an aluminum alloy, and the magnetic member holding portion 422 is also formed of an aluminum alloy. For this reason, the linear expansion coefficient of the disk 12 and the linear expansion coefficient of the magnetic member holding part 422 are the same or approximate. Thereby, the stress which generate | occur | produces between the disk 12 and the magnetic member holding | maintenance part 422 at the time of a temperature change is suppressed. On the other hand, the bush 421 of the present embodiment is formed of stainless steel with high hardness. For this reason, the bush 421 is firmly fixed to the shaft 41.

  The yoke 43 and the rotor magnet 44 are magnetic members provided on the rotating unit 4 side. The yoke 43 is fixed to the inner peripheral surface of the cylindrical portion 52 of the hub 42 with an adhesive. The rotor magnet 44 is fixed to the inner peripheral surface of the yoke 43 with an adhesive. Both the yoke 43 and the rotor magnet 44 have a substantially cylindrical shape with the central axis 9 as the center. The inner peripheral surface of the rotor magnet 44 faces the outer peripheral surface of the plurality of tooth portions 321b of the stator core 321 in the radial direction. The inner peripheral surface of the rotor magnet 44 is a magnetic pole surface in which N poles and S poles are alternately arranged.

  As described above, the magnetic member holding portion 422 of this embodiment is formed of an aluminum alloy. For this reason, the magnetic member holding | maintenance part 422 can be obtained cheaply compared with the case where stainless steel is used. However, the aluminum alloy itself hardly functions as a yoke. Therefore, in the present embodiment, the rotor magnet 44 is attached to the magnetic member holding portion 422 via a magnetic yoke 43. Thereby, the directivity of the magnetic flux generated from the rotor magnet 44 is improved. Thus, in the present embodiment, the cylindrical portion 52 of the magnetic member holding portion 422, the yoke 43, and the rotor magnet 44 are configured to overlap in the radial direction.

  In such a spindle motor 2, when a drive current is applied to the coil 322 of the stationary part 3, a radial magnetic flux is generated in the plurality of teeth 321 b of the stator core 321. Then, a torque in the circumferential direction is generated by the action of magnetic flux between the tooth portion 321 b and the rotor magnet 44, and the rotating portion 4 rotates about the central axis 9 with respect to the stationary portion 3. The disk 12 supported by the hub 42 rotates around the central axis 9 together with the shaft 41 and the hub 42.

<2-3. About the structure of the yoke and its vicinity>
Subsequently, the structure of the yoke 43 and the vicinity thereof will be further described. FIG. 4 is an enlarged vertical sectional view of the yoke 43 and its vicinity.

  As shown in FIG. 4, the inner peripheral surface of the cylindrical portion 52 of the magnetic member holding portion 422 includes a first inner peripheral surface 52a, a second inner peripheral surface 52b, and a third inner peripheral surface 52c. The second inner peripheral surface 52b is located above the first inner peripheral surface 52a, and the inner diameter thereof is smaller than the inner diameter of the first inner peripheral surface 52a. The third inner peripheral surface 52c is located above the second inner peripheral surface 52b, and the inner diameter thereof is smaller than the inner diameter of the third inner peripheral surface 52c. That is, the cylindrical part 52 of the magnetic member holding part 422 has an inner peripheral surface whose inner diameter is gradually reduced upward.

  The yoke 43 has a body portion 431 having a substantially cylindrical shape. An outer convex portion 432 protruding outward in the radial direction is formed at the lower end portion of the body portion 431. In addition, an inner convex portion 433 that protrudes inward in the radial direction is formed at the upper end portion of the body portion 431. The lower surface of the inner convex portion 433 is in contact with the upper surface of the rotor magnet 44.

  The adhesive 61 is held in an annular gap 70 including a radial gap 71 between the outer peripheral surface of the yoke 43 and the inner peripheral surface of the cylindrical portion 52 of the magnetic member holding portion 422. The radial gap 71 has a first gap 711, a second gap 712, and a third gap 713. The first gap 711 is located between the outer peripheral surface of the outer convex portion 432 of the yoke 43 and the first inner peripheral surface 52 a of the magnetic member holding portion 422. The first gap 711 communicates directly with an annular lower opening 80 described later. The second gap 712 is located between the outer peripheral surface of the body portion 431 of the yoke 43 and the second inner peripheral surface 52 b of the magnetic member holding portion 422. The radial gap between the second gaps 712 is smaller than the radial gap between the first gaps 711. The third gap 713 is located between the outer peripheral surface of the trunk portion 431 of the yoke 43 and the third inner peripheral surface 52 c of the magnetic member holding portion 422. The radial gap of the third gap 713 is even smaller than the radial gap of the second gap 712. As described above, the radial interval of the radial gap 71 gradually decreases upward.

  The body portion 431 of the yoke 43 is fitted inside the third inner peripheral surface 52c of the magnetic member holding portion 422. In many cases, the outer peripheral surface of the trunk portion 431 of the yoke 43 and the third inner peripheral surface 52c of the magnetic member holding portion 422 are partially in contact with each other. A third gap 713 is provided in a portion where the outer peripheral surface of the body portion 431 of the yoke 43 and the third inner peripheral surface 52 c of the magnetic member holding portion 422 are separated from each other. The third inner peripheral surface 52c serves as an alignment surface that limits the radial position of the yoke 43 within a predetermined error range. Thereby, the space | interval of the 1st clearance gap 711 and the 2nd clearance gap 712 is maintained substantially uniform over the perimeter.

  A tapered surface 52 d is formed below the first inner peripheral surface 52 a of the magnetic member holding portion 422, that is, at the lower end portion of the inner peripheral surface of the cylindrical portion 52. The inner diameter of the tapered surface 52d gradually increases downward. An annular lower opening 80 is provided between the outer peripheral surface of the outer convex portion 432 of the yoke 43 and the tapered surface 52 d of the magnetic member holding portion 422. The annular lower opening 80 communicates with the lower end portion of the annular gap 70, and the radial interval thereof is larger than the radial interval of the radial gap 71.

  The volume of the annular lower opening 80 is equal to or larger than the volume of the annular gap 70. For this reason, in step S <b> 3 of the manufacturing process described later, the annular lower opening 80 can hold the entire amount of the adhesive 61 interposed in the annular gap 70. Therefore, a necessary amount of the adhesive 61 can be supplied to the annular lower opening 80 at a time, and the supplied adhesive 61 can penetrate into the annular gap 70.

  FIG. 5 is a longitudinal sectional view showing the vicinity of the annular gap 70 and the annular lower opening 80 further enlarged than FIG. In the present embodiment, the portion indicated by cross hatching in FIG. 5, that is, the volume of the portion 80 a located above the lower end portion of the yoke 43 in the annular lower opening 80 is equal to the volume of the annular gap 70, Bigger than that. For this reason, the total amount of the adhesive 61 interposed in the annular gap 70 can be sufficiently retained. Thus, in the annular lower opening 80, the volume of the portion located above the higher one of the lower end of the magnetic member holding portion 422 and the lower end of the yoke 43 is equal to the volume of the annular gap 70, It is desirable to set the dimensions of the magnetic member holding portion 422 and the yoke 43 so as to be larger than that.

  The upper surface of the yoke 43 is abutted against the lower surface of the disk portion 51 of the magnetic member holding portion 422. However, when viewed microscopically, a minute axial gap 72 exists partially between the upper surface of the yoke 43 and the lower surface of the disk portion 51 of the magnetic member holding portion 422. A small amount of adhesive 61 is also present in the axial gap 72. Thereby, the magnetic member holding part 422 and the yoke 43 are more firmly fixed. The axial gap 72 constitutes a part of the annular gap 70.

  In the present embodiment, an annular groove 51 a is formed on the lower surface of the disk portion 51 of the magnetic member holding portion 422. The radially outer edge of the annular groove 51 a is positioned near the radially inner end of the axial gap 72. Further, the corner of the inner edge portion of the upper surface of the yoke 43 is formed in a curved surface shape. For this reason, the opening inside the radial gap 72 in the radial direction, that is, the upper opening of the annular gap 70 is tapered toward the radially inner side. When the adhesive 61 before curing penetrates to the upper opening, the adhesive 61 is attracted to the axial gap 72 side by the surface tension. Thereby, it is prevented that the adhesive 61 before hardening protrudes radially inward from the axial gap 72.

<2-4. Fixing procedure between hub and yoke>
Next, a procedure for fixing the hub 42 and the yoke 43 in the manufacturing process of the spindle motor 2 will be described with reference to the flowchart of FIG. 6 and FIGS. 7 to 9.

  When fixing the hub 42 and the yoke 43, first, as shown in FIG. 7, the yoke 43 is fitted and inserted inside the cylindrical portion 52 of the magnetic member holding portion 422 (step S1). The body portion 431 of the yoke 43 is fitted inside the third inner peripheral surface 52c of the magnetic member holding portion 422. Thereby, the radial position of the yoke 43 is determined. When the fitting insertion of the yoke 43 into the magnetic member holding part 422 is completed, an annular gap 70 and an annular lower opening 80 are formed between the magnetic member holding part 422 and the yoke 43 (step S2).

  Subsequently, as shown in FIG. 8, the adhesive 61 is supplied to the annular lower opening 80 (step S3). As described above, the volume of the annular lower opening 80 is equal to or larger than the volume of the annular gap 70. For this reason, in step S <b> 3, the entire amount of the adhesive 61 interposed in the annular gap 70 can be supplied to the annular lower opening 80 at a time. Thereby, it is possible to prevent bubbles from being mixed into the adhesive 61.

  Thereafter, the entire hub 42 and yoke 43 are carried into a heating furnace, and the adhesive 61 is heated (step S4). In the present embodiment, an adhesive 61 whose viscosity is lowered by heating is used. For this reason, the adhesive 61 held in the annular lower opening 80 gradually permeates the annular gap 70 as shown in FIG. As described above, in the present embodiment, the adhesive 61 is held in the annular lower opening 80 and the adhesive 61 penetrates into the annular gap 70 using the capillary force. For this reason, the adhesive 61 can be uniformly interposed in the annular gap 70.

  In particular, the radial gap 71 of the annular gap 70 gradually decreases in the radial direction from the first gap 711 toward the third gap 713. For this reason, the penetration of the adhesive 61 into the radial gap 71 is further promoted.

  The heating intensity and heating time in the heating furnace are adjusted in consideration of the penetration speed of the adhesive 61. Eventually, when the adhesive 61 penetrates the entire annular gap 70, the heating is stopped and the adhesive 61 is cured. The adhesive 61 is in a state of being uniformly distributed over the entire circumference of the annular gap 70. For this reason, the deformation of the magnetic member holding portion 422 accompanying the curing of the adhesive 61 is suppressed.

  Further, since the adhesive 61 is uniformly distributed in the circumferential direction, the rotational accuracy of the spindle motor 2 is also improved. Further, the magnetic member holding portion 422 and the yoke 43 are firmly fixed over the entire circumference. For this reason, the structural rigidity of the magnetic member holding part 422 and the yoke 43 is also improved.

  In particular, the magnetic member holding portion 422 of this embodiment is formed of an aluminum alloy. For this reason, compared with the case where stainless steel with high rigidity is used, distortion is likely to occur in the magnetic member holding portion 422. Further, since the cylindrical portion 52, the yoke 43, and the rotor magnet 44 of the magnetic member holding portion 422 overlap in the radial direction, the radial thickness of the cylindrical portion 52 is relatively limited. Therefore, in such a structure, it has a particularly high technical significance that the adhesive 61 is uniformly distributed in the circumferential direction so that the distortion of the magnetic member holding portion 422 can be prevented.

<3. Modification>
As mentioned above, although exemplary embodiment of this invention was described, this invention is not limited to said embodiment.

  The hub 42 may be composed of two members, the bush 421 and the magnetic member holding portion 422, as in the above embodiment, or may be composed of a single member. For example, the entire hub 42 may be formed of stainless steel as a single member. The disk 12 may be formed of other materials such as glass.

  Further, the rotor magnet 44 that is a magnetic member may be directly fixed to the inside of the cylindrical portion 52 of the hub 42 via an adhesive 61. That is, the yoke 43 may not be interposed between the cylindrical portion 52 of the hub 42 and the rotor magnet 44. In this case, an annular gap 70 and an annular lower opening 80 are provided between the cylindrical portion 52 of the hub 42 and the rotor magnet 44. The volume of the annular lower opening 80 may be equal to or greater than the volume of the annular gap 70.

  Further, a tapered surface may be provided at the lower end portion of the outer peripheral surface of the yoke 43, and the annular lower opening 80 may be provided between the tapered surface and the cylindrical portion 52. However, for example, when the magnetic member holding portion 422 is formed by cutting and the yoke 43 is formed by pressing, it is easier to manufacture a taper surface on the magnetic member holding portion 422 side.

  As the adhesive 61, a thermosetting resin can be used. For example, an acrylic resin, an epoxy resin, or a mixture thereof can be used. The adhesive 61 does not necessarily have to be reduced in viscosity by heating. The adhesive 61 may be any adhesive that can penetrate the radial gap 71 by capillary force in a state before being cured.

  The present invention can also be applied to a spindle motor for rotating a disk such as an optical disk.

  The present invention can be used in a spindle motor, a disk drive device, and a method of manufacturing a spindle motor.

DESCRIPTION OF SYMBOLS 1 Disc drive device 2,902 Spindle motor 3,903 Static part 4,904 Rotation part 9 Central axis 11 Apparatus housing 12 Disc 13 Access part 31 Base member 32 Stator unit 33 Static bearing unit 41 Shaft 42,942 Hub 43 York 44 Rotor Magnet 421 Bushing 422 Magnetic member holding part 431 Body part 432 Outer convex part 433 Inner convex part 51,951 Disk part 51a Annular groove 52,952 Cylindrical part 52a First inner peripheral surface 52b Second inner peripheral surface 52c Third inner periphery Surface 52d Tapered surface 53 Flange portion 61,961 Adhesive 70,970 Annular gap 71 Radial gap 72 Axial gap 80,980 Annular lower opening 711 First gap 712 Second gap 713 Third gap 943 Magnetic member

Claims (8)

A stationary part;
A rotating part that is rotatably supported with respect to the stationary part,
The rotating part is
A hub having a disk part extending in a radial direction with respect to a central axis extending in the vertical direction and a cylindrical part extending downward from an outer edge part of the disk part;
A magnetic member fixed to the inner peripheral surface of the cylindrical portion via an adhesive;
Between the hub and the magnetic member,
An annular gap including a radial gap between the inner circumferential surface of the cylindrical portion and the outer circumferential surface of the magnetic member;
An annular lower opening communicating with the lower end of the annular gap and having a larger radial interval than the radial gap;
A spindle motor having a volume of the annular lower opening equal to or larger than a volume of the annular gap. The spindle motor according to claim 1,
The magnetic member has a magnet and a yoke,
The cylindrical portion, the yoke, and the magnet overlap in the radial direction,
The hub is a spindle motor formed of an aluminum alloy. The spindle motor according to claim 1 or 2,
The radial clearance is
A first gap directly communicating with the annular lower opening;
A spindle motor including a second gap positioned above the first gap and having a smaller radial interval than the first gap. The spindle motor according to claim 3, wherein
The radial clearance is
A spindle motor further comprising a third gap positioned above the second gap and having a smaller radial interval than the second gap. In the spindle motor according to any one of claims 1 to 4,
A spindle motor in which the upper opening of the annular gap is tapered. In the spindle motor according to any one of claims 1 to 5,
The hub is a spindle motor having a tapered surface facing the annular lower opening. A spindle motor according to any one of claims 1 to 6,
An access unit that performs at least one of reading and writing of information on the disk supported by the hub of the spindle motor;
A housing for housing the spindle motor and the access unit;
A disk drive device comprising: A hub having a disk part extending in a radial direction with respect to a central axis extending vertically and a cylindrical part extending downward from an outer edge part of the disk part, and an inner peripheral surface of the cylindrical part are fixed via an adhesive A method of manufacturing a spindle motor having a magnetic member,
a) fitting and inserting the magnetic member inside the cylindrical portion of the hub in the radial direction;
b) An annular gap including the radial gap between the inner peripheral surface of the cylindrical portion and the outer peripheral surface of the magnetic member between the hub and the magnetic member after completing the fitting insertion in the step a). And a lower annular opening communicating with the lower end portion of the annular gap and having a larger radial interval than the radial gap and having a volume equal to or larger than the volume of the annular gap; ,
c) after the step b), supplying an adhesive to the annular lower opening;
d) after the step c), heating the adhesive;
A method for manufacturing a spindle motor comprising:

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