JP5309837B2 - Spindle motor and disk drive device - Google Patents

Description

  The present invention relates to a spindle motor that rotates a disk around a predetermined central axis, and a disk drive device including the spindle motor.

  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 fixed portion fixed to the housing of the apparatus and a rotating portion that rotates by mounting a disk. The spindle motor generates a circumferential torque centered on the central axis by a magnetic flux generated between the fixed portion and the rotating portion, whereby the disk mounted on the rotating portion and the rotating portion with respect to the fixed portion. Rotate.

  Also, some conventional spindle motors have a thrust yoke attached to the upper surface of the fixed portion. The thrust yoke serves to stabilize the rotational posture of the rotating part by attracting the rotating part to the fixed part side by a magnetic attraction generated between the thrust yoke and the rotor magnet fixed to the rotating part.

  A conventional spindle motor having a thrust yoke is disclosed in Patent Document 1, for example.

JP 2007-43893 A

  In a conventional spindle motor having a thrust yoke, the thrust yoke is fixed to the base member of the fixing portion with an adhesive. However, in the conventional spindle motor, since an adhesive is interposed between the flat upper surface of the base member and the flat lower surface of the thrust yoke, when the base member and the thrust yoke are brought close to each other, Only a small amount of adhesive could be held between the yoke. For this reason, it has been difficult to fix the base member and the thrust yoke with high adhesive strength.

  On the other hand, a magnetic attractive force acts strongly between the thrust yoke and the rotor magnet. For this reason, unless the base member and the thrust yoke are fixed with high adhesive strength, the thrust yoke may be peeled off from the base member by a magnetic attractive force.

  The present invention has been made in view of such circumstances, and a spindle motor and a disk drive capable of improving the adhesive strength between a base member and a thrust yoke and preventing the thrust yoke from peeling off from the base member. An object is to provide an apparatus.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a spindle motor that rotates a disk about a predetermined central axis, and has a fixed part and a mounting part for mounting the disk, and the central axis A rotating part that rotates about the central axis, and the fixing part is fixed to the base member and the base member via an adhesive. A thrust yoke that is axially opposed to the magnet, and at least one of the base member and the thrust yoke has a reservoir portion that holds the adhesive on a surface that contacts the adhesive. The pool portion is formed in at least a part of a region in which the magnet is projected in the axial direction.

  The invention according to claim 2 is the spindle motor according to claim 1, wherein the pool portion includes a plurality of recesses arranged on a surface in contact with the adhesive.

  The invention according to claim 3 is the spindle motor according to claim 2, wherein the plurality of recesses are arranged over the entire surface in contact with the adhesive.

  The invention according to claim 4 is the spindle motor according to any one of claims 1 to 3, wherein the pool portion is formed on a surface of the thrust yoke that contacts the adhesive. It is characterized by.

  The invention according to claim 5 is the spindle motor according to claim 4, wherein the thrust yoke is bonded to the base member in the axial direction and bonded to the base member in the radial direction. And the reservoir is formed on both the first adhesive surface and the second adhesive surface.

  The invention according to claim 6 is the spindle motor according to claim 4 or 5, wherein the surface of the thrust yoke that faces the magnet is a flat surface that does not include a shape equivalent to the reservoir portion. It is characterized by that.

  The invention according to claim 7 is the spindle motor according to any one of claims 1 to 6, wherein the thrust yoke is formed by punching, and the magnet of the thrust yoke is provided on the magnet. A projecting portion resulting from the punching process is disposed at an edge portion of the opposing surface, and a curved surface resulting from the punching process is provided at an edge portion of the surface facing the base member of the thrust yoke. The portion is arranged.

  The invention according to claim 8 is the spindle motor according to any one of claims 1 to 7, wherein a surface of the thrust yoke that contacts the adhesive is a surface modified by irradiation with ultraviolet rays. It is characterized by being.

  The invention according to claim 9 is the spindle motor according to any one of claims 1 to 8, wherein the base member covers a main body portion mainly made of aluminum and a surface of the main body portion. The surface of the base member that contacts the adhesive is an exposed surface from which the main body is exposed.

  A tenth aspect of the present invention is a disk drive device that performs one or both of reading and writing information while rotating a disk, and the spindle motor according to any one of the first to ninth aspects, An access unit that reads and / or writes information to and from the disk, and a housing that houses the spindle motor and the access unit are provided.

  According to the first to tenth aspects of the present invention, at least one of the base member and the thrust yoke is formed with a reservoir for holding the adhesive on the surface in contact with the adhesive. For this reason, the adhesive strength between the base member and the thrust yoke can be improved, and the thrust yoke can be prevented from peeling off from the base member. According to the first to tenth aspects of the present invention, the reservoir is formed in at least a part of a region in which the magnet is projected in the axial direction. For this reason, the adhesive strength between the base member and the thrust yoke can be improved in the region where the magnetic force of the magnet acts greatly.

  In particular, according to the second aspect of the present invention, the reservoir portion includes a plurality of concave portions arranged on the surface in contact with the adhesive. For this reason, a large amount of adhesive can be held while suppressing the depth of each recess.

  In particular, according to the third aspect of the present invention, the plurality of recesses are arranged over the entire area in contact with the adhesive. For this reason, the adhesive strength between the base member and the thrust yoke can be improved over the entire area of the adhesive surface.

  In particular, according to the fourth aspect of the present invention, the reservoir is formed on the surface of the thrust yoke that contacts the adhesive. For this reason, the reservoir can be easily formed in the process of manufacturing the thrust yoke.

  In particular, according to the invention described in claim 5, the thrust yoke has a first adhesive surface that is bonded to the base member in the axial direction and a second adhesive surface that is bonded to the base member in the radial direction. The reservoir portion is formed on both the first adhesive surface and the second adhesive surface. For this reason, the adhesive strength between the base member and the thrust yoke can be further improved.

  In particular, according to the sixth aspect of the present invention, the surface of the thrust yoke that faces the magnet is a flat surface that does not include the same shape as the reservoir. For this reason, the adhesive strength between the thrust yoke and the base member can be improved while stabilizing the magnetic field between the magnet and the thrust yoke.

  In particular, according to the seventh aspect of the present invention, the projecting portion resulting from the punching process is arranged at the edge of the surface of the thrust yoke facing the magnet, and faces the base member of the thrust yoke. A curved surface portion resulting from the punching process is disposed at the edge portion of the surface. For this reason, an adhesive agent can be hold | maintained between a curved surface part and a base member, and, thereby, the adhesive strength between a base member and a thrust yoke can further be improved.

  In particular, according to the eighth aspect of the invention, the surface of the thrust yoke that contacts the adhesive is a surface that has been modified by irradiation with ultraviolet rays. For this reason, the wettability of the adhesive with respect to the thrust yoke is improved, and the adhesive strength between the base member and the thrust yoke can be further improved.

  In particular, according to the ninth aspect of the present invention, the base member has a main body portion mainly composed of aluminum and an electrodeposition coating portion that covers the surface of the main body portion, and contacts the adhesive of the base member. The surface to be exposed is an exposed surface from which the main body is exposed. For this reason, the main-body part of a base member can be protected by an electrodeposition coating part, without reducing the adhesive strength of a base member and a thrust yoke.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, the shape and positional relationship of each member will be described with the direction along the central axis A as the vertical direction, the rotation part 4 side as “upper” and the fixing part 3 side as “lower”. However, this is defined only in the vertical direction for convenience of explanation, and does not limit the installation posture when the spindle motor or the disk drive device of the present invention is mounted on an actual device.

<1. Configuration of disk drive>
FIG. 1 is a longitudinal sectional view of a disk drive device 2 according to an embodiment of the present invention. The disk drive device 2 is a hard disk device that reads information from the magnetic disk 22 and writes information to the magnetic disk 22 while rotating the two magnetic disks 22. As shown in FIG. 1, the disk drive device 2 mainly includes a device housing 21, two magnetic disks (hereinafter simply referred to as “disks”) 22, an access unit 23, and a spindle motor 1.

  The device housing 21 includes a cup-shaped first housing member 211 and a plate-shaped second housing member 212. The first housing member 211 has an opening in the upper part, and the spindle motor 1 and the access unit 23 are installed on the bottom surface inside the first housing member 211. The second housing member 212 is joined to the first housing member 211 so as to cover the upper opening of the first housing member 211, and the interior of the device housing 21 surrounded by the first housing member 211 and the second housing member 212. In the space 213, two disks 22, the access unit 23, and the spindle motor 1 are accommodated. The internal space 213 of the device housing 21 is a clean space with less dust and dirt.

  Each of the two disks 22 is a disc-shaped information recording medium having a hole in the center. Each disk 22 is mounted on the hub 42 of the spindle motor 1 and is stacked up and down via a spacer 221. On the other hand, the access unit 23 includes four heads 231 facing the upper and lower surfaces of the two disks 22, an arm 232 that supports each head 231, and a swing mechanism 233 that swings the arm 232. Yes. The access unit 23 swings the four arms 232 along the disk 22 by the swing mechanism 233 and causes the four heads 231 to access a required position of the disk 22, thereby recording the recording surface of each rotating disk 22. Read and write information. Note that the head 231 may perform only one of reading and writing of information with respect to the recording surface of the disk 22.

<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. As shown in FIG. 2, the spindle motor 1 includes a fixed portion 3 that is fixed to the device housing 21 of the disk drive device 2, and a rotating portion 4 that mounts the disk 22 and rotates about the central axis A. ing.

  First, the structure of the fixing | fixed part 3 is demonstrated. The fixed portion 3 mainly includes a base member 31, a stator core 32, a coil 33, a sleeve 34, and a thrust yoke 35.

  The base member 31 is a part of the first housing member 211 (see FIG. 1) of the disk drive device 2, and is formed integrally with other portions of the first housing member 211 using aluminum as a main material. The base member 31 is formed with a substantially cylindrical holder portion 311 that protrudes in the axial direction (a direction along the central axis A; the same applies hereinafter) around the central axis A. A through-hole for inserting the sleeve 34 is formed on the inner side of the holder portion 311 in the radial direction (a direction orthogonal to the central axis A; the same applies hereinafter). Further, the outer surface in the radial direction of the holder portion 311 is an attachment surface on which the stator core 32 is fitted.

  In this embodiment, the base member 31 and the first housing member 211 are integrally formed. However, the base member 31 and the first housing member 211 may be separate members fixed to each other. Good.

  The stator core 32 and the coil 33 function as a magnetic flux generator that generates a magnetic flux according to the drive current. The stator core 32 has an annular core back 321 fitted to the outer peripheral surface of the holder portion 311 of the base member 31 and a plurality of teeth portions 322 protruding outward from the core back 321 in the radial direction. ing. The stator core 32 is obtained, for example, by punching a laminated steel sheet in which electromagnetic steel sheets are laminated in the axial direction.

  The coil 33 is constituted by a conductive wire wound around each tooth portion 322 of the stator core 32. The coil 33 is connected to a power supply device (not shown) via a connector (not shown). When a drive current is applied to the coil 33 from the power supply device via the connector, a radial magnetic flux is generated in the tooth portion 322. The magnetic flux generated in the tooth portion 322 interacts with the magnetic flux of the rotor magnet 43 described later, and generates torque for rotating the rotating portion 4 about the central axis A.

  The sleeve 34 is a substantially cylindrical member that is disposed on the outer peripheral side of the shaft 41 and whose inner peripheral surface 34 a faces the outer peripheral surface 41 a of the shaft 41. The sleeve 34 is formed of a metal material such as stainless steel or copper alloy, for example. The sleeve 34 is inserted inside the holder portion 311 of the base member 31 and is fixed to the holder portion 311 with an adhesive. A projecting portion 341 that protrudes downward is formed on the lower surface of the sleeve 34. In addition, a cap 37 for sealing the opening on the lower end side of the sleeve 34 is fixed to the protruding portion 341.

  In a minute gap (for example, about several μm) between the inner circumferential surface 34 a of the sleeve 34 and the outer circumferential surface 41 a of the shaft 41 and a minute gap between the lower surface of the shaft 41 and the upper surface of the cap 37, The lubricating oil 51 is continuously filled. As the lubricating oil 51, for example, an oil mainly composed of an ester such as a polyol ester oil or a diester oil is used.

  A radial dynamic pressure groove array (not shown) for generating fluid dynamic pressure in the lubricating oil 51 interposed between the outer peripheral surface 41 a of the shaft 41 and the inner peripheral surface 34 a of the sleeve 34 is formed on the inner peripheral surface 34 a of the sleeve 34. ) Is formed. The radial dynamic pressure groove array is, for example, a so-called “herringbone” groove array in which a plurality of bowl-shaped grooves are arranged in the circumferential direction. When the shaft 41 rotates with respect to the sleeve 34, the lubricating oil 51 is pressurized by the radial dynamic pressure groove array, and the shaft 41 rotates while being supported in the radial direction by the fluid dynamic pressure generated in the lubricating oil 51. The radial dynamic pressure groove array may be formed on either the inner peripheral surface 34 a of the sleeve 34 or the outer peripheral surface 41 a of the shaft 41.

  In addition, fluid dynamic pressure is generated in the lubricating oil 51 interposed between the upper surface 411a of the flange 411 and the inner lower surface 34b of the sleeve 34 on the inner lower surface 34b of the sleeve 34 facing the upper surface 411a of the flange 411 described later. A thrust dynamic pressure groove array (not shown) is formed. The thrust dynamic pressure groove array is constituted by, for example, a plurality of spiral grooves centered on the central axis A. When the shaft 41 rotates with respect to the sleeve 34, the lubricating oil 51 is pressurized by the thrust dynamic pressure groove array, and the shaft 41 rotates while being supported in the axial direction by the fluid dynamic pressure generated in the lubricating oil 51. The thrust dynamic pressure groove array may be formed on either the inner lower surface 34 b of the sleeve 34 or the upper surface 411 a of the flange portion 411.

  As described above, the sleeve 34 and the cap 37 serve as a fixed bearing portion (a bearing member on the fixed portion side) that allows the shaft 41 to rotate about the central axis A while supporting the shaft 41 in the radial direction and the axial direction. Function. The sleeve 34, the cap 37, the shaft 41, and the lubricating oil 51 constitute a bearing unit that connects the fixed portion 3 and the rotating portion 4 in a relatively rotatable state about the central axis A.

  The thrust yoke 35 is an annular member fixed to the upper surface of the base member 31. The thrust yoke 35 serves to stabilize the rotational posture of the rotating unit 4 by attracting the rotating unit 4 to the fixed unit 3 side by a magnetic attractive force generated between the thrust yoke 35 and a rotor magnet 43 described later. The thrust yoke 35 is press-fitted inside an annular raised portion 312 formed on the upper surface of the base member 31, and is fixed to the upper surface of the base member 31 with an adhesive.

  The thrust yoke 35 is formed of a magnetic material such as an electromagnetic steel plate (for example, a silicon steel plate), a ferromagnetic stainless steel (for example, SUS430), or a cold rolled steel plate (for example, SPCC, SPCE). Further, the surface of the thrust yoke 35 is subjected to electroless nickel plating for preventing the generation of rust as necessary.

  Next, the configuration of the rotating unit 4 of the spindle motor 1 will be described. The rotating part 4 mainly has a shaft 41, a hub 42, and a rotor magnet 43.

  The shaft 41 is a substantially columnar member disposed along the central axis A. The shaft 41 is supported so as to be rotatable with respect to the sleeve 34 in a state of being inserted into the inside (bearing hole) of the sleeve 34. A flange portion 411 for preventing the shaft 41 from slipping out of the sleeve 34 is formed at the lower end portion of the shaft 41. The flange portion 411 protrudes in the radial direction from the outer peripheral surface of the shaft 41, and the upper surface 411 a of the flange portion 411 faces the inner lower surface 34 b of the sleeve 34.

  When an upward force is applied to the rotating portion 4, the upper surface 411a of the flange portion 411 contacts the inner lower surface 34b of the sleeve 34 (or is interposed between the inner lower surface 34b of the sleeve 34 and the upper surface 411a of the flange portion 411). Thus, the upward force of the flange portion 411 is attenuated by the lubricating oil 51 that is performed), thereby preventing the fixed portion 3 and the rotating portion 4 from being separated.

  In the present embodiment, the shaft 41 and the flange portion 411 are integrally formed, but the shaft 41 and the flange portion 411 may be separate members fixed to each other.

  The hub 42 includes a bush 44 that is joined to the head of the shaft 41 by press-fitting or shrink fitting, and a hub main body 45 that is fixed to the outer peripheral surface of the bush 44 and holds the two disks 22. The bush 44 and the hub main body 45 rotate around the central axis A together with the shaft 41.

  The hub main body 45 is fixed to the outer peripheral surface of the bush 44 and spreads outward in the radial direction, a cylindrical portion 452 extending downward from an outer edge portion of the flat plate portion 451, and a cylindrical portion 452. And a flange portion 453 extending from the lower end portion toward the outside in the radial direction. The outer peripheral surface 45 a of the cylindrical portion 452 serves as a contact surface that contacts the inner peripheral portion (inner peripheral surface or inner peripheral edge) of the disk 22. The upper surface 45b of the flange portion 453 serves as a mounting surface on which the disk 22 is mounted.

  The two disks 22 are stacked in a horizontal posture on the upper surface 45 b of the flange portion 453. That is, the lower disk 22 is placed on the upper surface 45 b of the flange portion 453, and the upper disk 22 is placed thereon via the spacer 221. The inner peripheral portion of each disk 22 is in contact with the outer peripheral surface 45a of the cylindrical portion 452, whereby the radial movement of each disk 22 is restricted.

  The disk 22 of the present embodiment is made of aluminum as a main material, and the hub main body 45 is also made of aluminum. For this reason, the linear expansion coefficient of the disk 22 and the linear expansion coefficient of the hub main body 45 are the same or approximate. Therefore, even when the environmental temperature or the temperature inside the spindle motor 1 changes, no excessive stress is generated between the disk 22 and the hub main body 45. On the other hand, the bush 44 of the present embodiment is made of stainless steel having a high hardness in order to maintain a state of being firmly fixed to the shaft 41.

  The hub 42 of the present embodiment is configured by two members, the bush 44 and the hub main body 45, but the hub 42 may be configured by a single member. For example, when using a disk mainly made of glass, the hub 42 may be formed as a single member from a material such as stainless steel having a linear expansion coefficient close to that of the disk.

  The rotor magnet 43 is attached to the inner peripheral surface of the cylindrical portion 452 of the hub main body 45 via a back yoke 431. The rotor magnet 43 has an annular shape so as to surround the central axis A. The inner peripheral surface of the rotor magnet 43 is a magnetic pole surface in which N poles and S poles are alternately arranged, and faces the outer peripheral surfaces of the plurality of teeth portions 322 of the stator core 32 in the radial direction. The lower surface of the rotor magnet 43 faces the upper surface of the thrust yoke 35 fixed to the upper surface of the base member 31 in the axial direction.

  In such a spindle motor 1, when a drive current is applied to the coil 33 of the fixed portion 3, a radial magnetic flux is generated in the plurality of teeth portions 322 of the stator core 32. A circumferential torque is generated by the action of the magnetic flux between the tooth portion 322 and the rotor magnet 43, and the rotating portion 4 rotates about the central axis A with respect to the fixed portion 3. The two disks 22 mounted on the hub main body 45 rotate about the central axis A together with the shaft 41, the bush 44, and the hub main body 45.

<3. Adhesion between base member and thrust yoke>
FIG. 3 is a partial longitudinal sectional view of the spindle motor 1 showing the configuration of the thrust yoke 35 and the vicinity thereof. As described above, the thrust yoke 35 is press-fitted inside the annular raised portion 312 formed on the upper surface of the base member 31, and is fixed to the upper surface of the base member 31 with the adhesive 36.

  As the adhesive 36, for example, a thermosetting adhesive can be used. Note that as the adhesive 36, an adhesive having ultraviolet curable properties and thermosetting properties, and an adhesive having anaerobic properties, ultraviolet curable properties, and thermosetting properties may be used. If an adhesive having an ultraviolet curable property and anaerobic property is used as the adhesive 36, the adhesive 36 is temporarily cured after being temporarily cured by irradiation of ultraviolet rays. Therefore, the thrust yoke 35 can be fixed without reducing the production tact of the spindle motor 1. If an adhesive having a large amount of epoxy component is used, the adhesive strength between the base member 31 and the thrust yoke 35 can be further improved.

  As shown in FIG. 3, an undercut portion 313 for preventing the outer peripheral edge of the lower surface of the thrust yoke 35 from climbing is formed inside the raised portion 312 of the base member 31.

  A plurality of recesses 351 are formed on the lower surface of the thrust yoke 35 (the surface in contact with the adhesive 36). The plurality of recesses 351 serve as a reservoir for holding a part of the adhesive 36 interposed between the base member 31 and the thrust yoke 35. That is, the plurality of recesses 351 serve to secure a space in which the adhesive 36 is held between the base member 31 and the lower surface of the thrust yoke 35 even when the base member 31 is close to the lower surface. A larger amount of adhesive 36 is held between the member 31 and the thrust yoke 35 than in the prior art. Therefore, in the spindle motor 1 of the present embodiment, the base member 31 and the thrust yoke 35 are fixed with high adhesive strength, and the thrust yoke 35 is prevented from peeling off from the base member 31.

  FIG. 4 is a view of the thrust yoke 35 of the present embodiment as viewed from the lower surface side. As shown in FIG. 4, the plurality of recesses 351 are regularly arranged on the entire lower surface of the thrust yoke 35. In the present embodiment, each recess 351 is a conical recess, but may be a recess having another shape such as a hemisphere. The diameter of each recessed part 351 should just be about 0.1-0.2 mm, for example, and the depth of each recessed part 351 should just be about 0.02-0.05 mm, for example. Further, the pitch of the plurality of recesses 351 (the distance between the centers of the two nearest recesses 351) may be about 0.5 mm, for example.

  As described above, in the present embodiment, the plurality of recesses 351 are regularly arranged on the entire lower surface of the thrust yoke 35. For this reason, the adhesive strength between the base member 31 and the thrust yoke 35 can be improved over the entire adhesive surface. However, the plurality of recesses 351 are not necessarily formed on the entire lower surface of the thrust yoke 35, and may be formed in at least a part of the region S (see FIG. 3) in which the rotor magnet 43 is projected in the axial direction. . In this way, the adhesive strength between the base member 31 and the thrust yoke 35 can be improved in a region where the magnetic force of the rotor magnet 43 is particularly large.

  On the other hand, as shown in FIG. 3, the upper surface of the thrust yoke 35 (the surface facing the rotor magnet 43) is a flat surface that does not include the same shape as the recess 351. If a concavo-convex shape is formed on the upper surface of the thrust yoke 35, the magnetic field generated between the rotor magnet 43 and the thrust yoke 35 is disturbed, which causes rotational vibration and vibration of the spindle motor 1. In the spindle motor 1 of the present embodiment, since the upper surface of the thrust yoke 35 is a flat surface, the magnetic field between the rotor magnet 43 and the thrust yoke 35 is not disturbed.

  In the manufacturing process of the spindle motor 1, for example, when the thrust yoke 35 is formed by punching using a progressive die, the plurality of recesses 351 may be formed by pressing in the progressive die before punching. . In that case, a plurality of recesses 351 may be formed on the entire surface of one side of the progressive die before punching, or a plurality of recesses 351 may be formed only in a region to be the thrust yoke 35 on one side of the progressive die. Also good. As described above, if the plurality of recesses 351 are formed in the progressive die before punching, the plurality of recesses 351 can be easily formed without reducing the dimensional accuracy of the thrust yoke 35 after punching.

  Further, it is desirable to modify the lower surface of the thrust yoke 35 by irradiating the lower surface of the thrust yoke 35 with ultraviolet rays before fixing the punched thrust yoke 35 to the base member 31. Specifically, for example, in a known UV ozone cleaning device, the lower surface of the thrust yoke 35 may be irradiated with ultraviolet rays for a predetermined time. When the ultraviolet ray is irradiated, the lower surface of the thrust yoke 35 is in a state where the organic compound is reduced and the hydrophilicity (wetting property) is improved. Thereby, the adhesiveness of the adhesive 36 to the lower surface of the thrust yoke 35 is improved, and the adhesive strength between the base member 31 and the thrust yoke 35 can be further improved.

  Also, as shown in FIG. 3, a resin electrodeposition coating 31b (EB coating) is formed on the surface of the main body 31a of the base member 31 mainly made of aluminum. The electrodeposition coating portion 31b protects the base member 31 from adhesion of particles and energization, and contributes to improvement of the aesthetic appearance of the base member 31. However, in this embodiment, the electrodeposition coating part 31b is not formed in the part which contacts the adhesive agent 36 among the upper surfaces of the base member 31, and the main-body part 31a is exposed. For this reason, the adhesiveness of the adhesive 36 with respect to the base member 31 is not reduced by the electrodeposition coating portion 31b.

  FIG. 5 is an enlarged vertical sectional view of the vicinity of the end edge portion of the thrust yoke 35. When the thrust yoke 35 is formed by punching as described above, a protruding portion 352 (so-called “burr”) is formed on the edge of one surface of the thrust yoke 35, and the other end of the thrust yoke 35 is formed. A curved surface portion 353 (so-called “sag”) is formed at the edge of the surface. In the present embodiment, the thrust yoke 35 is disposed so that such a protruding portion 352 is located on the upper surface side and the curved surface portion 353 is located on the lower surface side. For this reason, the adhesive 36 is held by the capillary force (surface tension) between the upper surface of the base member 31 and the curved surface portion 353 of the thrust yoke 35. Thereby, the adhesive strength between the base member 31 and the thrust yoke 35 is further improved.

<4. Modification>
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment.

  In the above embodiment, the plurality of recesses 351 are formed only on the lower surface of the thrust yoke 35, but the recesses 351 may also be formed on the side surfaces of the thrust yoke 35 as shown in FIG. Further, as shown in FIG. 7, the recessed portion 351 may be opposed to the raised portion 312 by bending the thrust yoke 35 after punching.

  In the example of FIGS. 6 and 7, the thrust yoke 35 is bonded to the upper surface of the base member 31 in the axial direction, and the second bonded to the raised portion 312 of the base member 31 in the radial direction. Adhesive surface 35b. A plurality of recesses 351 are formed on both the first adhesive surface 35a and the second adhesive surface 35b. For this reason, the adhesive strength between the base member 31 and the thrust yoke 35 can be further improved.

  In particular, in the form of FIG. 6, a plurality of recesses 351 can be formed in the progressive die before punching, and therefore the recesses 351 can be formed relatively easily in the manufacturing process of the thrust yoke 35. Moreover, in the form of FIG. 6, the rigidity of the thrust yoke 35 itself is also improved.

  Further, in the above embodiment, the plurality of recesses 351 are formed in the thrust yoke 35, but a plurality of recesses 351 may be formed on the upper surface of the base member 31, as shown in FIG. As a method for forming the plurality of recesses 351 on the base member 31 side, for example, when the base member 31 is cast, the plurality of recesses 351 may be formed together with other shapes. Or you may make it form the recessed part 351 by the press work in the base member 31 after casting.

  In other words, the recess 351 may be formed on the surface that contacts the adhesive 36 of at least one of the base member 31 and the thrust yoke 35.

  In the above-described embodiment, the plurality of recesses 351 are formed as the reservoir for holding the adhesive 36, but the reservoir does not necessarily have to be the plurality of recesses 351. For example, as shown in FIG. 9, an annular groove 354 may be formed on the lower surface of the thrust yoke 35 as a reservoir for holding the adhesive 36. In other words, it is only necessary to form a reservoir for holding the adhesive 36 between the base member 31 and the thrust yoke 35 by forming an uneven shape on at least one of the base member 31 and the thrust yoke 35. However, as in the above-described embodiment, if a plurality of concave portions 351 are formed as the reservoir portions of the adhesive 36, it is desirable that a large amount of adhesive can be held while suppressing the depth of each concave portion 351.

  The spindle motor 1 of the above embodiment is a so-called “shaft rotation” type spindle motor in which the shaft 41 rotates together with the hub 42. However, the spindle motor of the present invention is based on the shaft fixed to the base member. A so-called “shaft fixed” type spindle motor in which the sleeve and the hub rotate may be used.

  In the above embodiment, the spindle motor 1 for rotating the magnetic disk 22 has been described. However, the present invention can also be applied to a spindle motor for rotating another disk such as an optical disk.

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 fragmentary longitudinal cross-sectional view of the spindle motor which showed the structure of the thrust yoke and its vicinity. It is the figure which looked at the thrust yoke from the lower surface side. It is an enlarged vertical sectional view near the end edge portion of the thrust yoke. It is a fragmentary longitudinal cross-sectional view of the spindle motor which concerns on a modification. It is a fragmentary longitudinal cross-sectional view of the spindle motor which concerns on a modification. It is a fragmentary longitudinal cross-sectional view of the spindle motor which concerns on a modification. It is a fragmentary longitudinal cross-sectional view of the spindle motor which concerns on a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Spindle motor 2 Disc drive device 3 Fixing part 4 Rotating part 21 Apparatus housing 22 Disk 23 Access part 31 Base member 31a Main body part 31b Electrodeposition coating part 32 Stator core 33 Coil 34 Sleeve 35 Thrust yoke 35a 1st adhesion surface 35b 2nd Adhesive surface 36 Adhesive 41 Shaft 42 Hub 43 Rotor magnet 44 Bush 45 Hub body 51 Lubricating oil 351 Recess 352 Protruding part 353 Curved part 354 Groove A Central axis S Area where the rotor magnet is projected in the axial direction

Claims (10)

A spindle motor that rotates a disc around a predetermined central axis,
A fixed part;
A rotating portion that has a mounting portion for mounting the disc and rotates about the central axis;
With
The rotating part has a magnet disposed around the central axis,
The fixing portion includes a base member, and a thrust yoke fixed to the base member via an adhesive and facing the magnet in the axial direction,
At least one of the base member and the thrust yoke is formed with a reservoir for holding the adhesive on a surface that contacts the adhesive,
The spindle motor according to claim 1, wherein the pool portion is formed in at least a part of a region in which the magnet is projected in the axial direction. The spindle motor according to claim 1,
The spindle motor according to claim 1, wherein the pool portion includes a plurality of recesses arranged on a surface in contact with the adhesive. The spindle motor according to claim 2,
The spindle motor according to claim 1, wherein the plurality of recesses are arranged over the entire surface in contact with the adhesive. A spindle motor according to any one of claims 1 to 3,
The spindle motor according to claim 1, wherein the pool portion is formed on a surface of the thrust yoke that contacts the adhesive. The spindle motor according to claim 4,
The thrust yoke has a first bonding surface bonded in the axial direction to the base member and a second bonding surface bonded in the radial direction to the base member,
The spindle motor, wherein the pool portion is formed on both the first adhesive surface and the second adhesive surface. The spindle motor according to claim 4 or 5, wherein
The spindle motor according to claim 1, wherein a surface of the thrust yoke that faces the magnet is a flat surface that does not include a shape equivalent to the reservoir portion. A spindle motor according to any one of claims 1 to 6,
The thrust yoke is created by punching,
On the edge portion of the surface of the thrust yoke that faces the magnet, a protruding portion resulting from the punching process is disposed,
A spindle motor characterized in that a curved surface portion resulting from the punching process is disposed at an edge portion of a surface of the thrust yoke facing the base member. A spindle motor according to any one of claims 1 to 7,
The spindle motor according to claim 1, wherein a surface of the thrust yoke that contacts the adhesive is a surface that has been modified by irradiation with ultraviolet rays. A spindle motor according to any one of claims 1 to 8,
The base member has a main body part mainly made of aluminum, and an electrodeposition coating part covering the surface of the main body part,
The spindle motor according to claim 1, wherein the surface of the base member that contacts the adhesive is an exposed surface from which the main body is exposed. A disk drive device that performs one or both of reading and writing information while rotating a disk,
A spindle motor according to any one of claims 1 to 9,
An access unit for performing one or both of reading and writing information on the disk;
A housing for housing the spindle motor and the access unit;
A disk drive device comprising:

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