JP2023141733A - Spindle motor, hard disk drive device, and manufacturing method of spindle motor - Google Patents

Abstract

To provide a spindle motor having high joint force between a base plate and a support member.SOLUTION: A spindle motor 3 includes: a base plate 10 having a through hole 11; a support member which is inserted into the through hole 11; a rotor 30 supported so as to be rotatable relative to the support member; an annular groove 13 which is provided on an inner peripheral surface 11A of the through hole 11 facing an outer peripheral surface of the support member; and an epoxy system electrophoretic coating film 14 formed on the annular groove 13.SELECTED DRAWING: Figure 2

Description

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

A spindle motor that fixes a support member to a base plate is required to increase the axial load that the support member can support. One possible measure is to improve the bonding force between the base plate and the support member.

For example, Patent Document 1 discloses a technique for improving bonding force by forming a bonding groove on a bonding surface of a through hole of a base plate.

Japanese Patent Application Publication No. 2013-135604

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a spindle motor that has a high bonding force between a base plate and a support member.

In order to solve the above problems, we have provided a base plate having a through hole, a support member inserted into the through hole, a rotating part rotatably supported with respect to the support member, and an outer peripheral surface of the support member. A spindle motor is provided that includes an annular groove provided on the inner circumferential surface of the opposing through hole, and a resin-based electrodeposition coating film formed in the groove.

According to the present invention, the bonding force between the base plate of the spindle motor and the support member is high.

1 is a perspective view of a hard disk drive device 1. FIG. FIG. 3 is a cross-sectional view of a spindle motor 3 whose support member is a shaft 20. FIG. 3 is a cross-sectional view of the base plate 10. FIG. 3 is a side view of the shaft 20. FIG. 3 is an enlarged view of section V in FIG. 2. FIG. 3 is a flowchart of a method for manufacturing a spindle motor 3 whose supporting member is a shaft 20. FIG. 3 is a diagram showing a process in which an annular groove 13 and an epoxy electrodeposition coating film 14 are formed in a through hole 11. FIG. 3 is a cross-sectional view of the spindle motor 3 whose supporting member is a bearing sleeve 420. FIG. 4 is a sectional view of a base plate 410. FIG. 9 is an enlarged view of the X section in FIG. 8. FIG. 3 is a flowchart of a method for manufacturing a spindle motor 3 whose supporting member is a bearing sleeve 420. FIG. 5 is a diagram showing a process in which an annular groove 414 and an epoxy electrodeposition coating film 415 are formed in a through hole 411. FIG.

Embodiments of the present invention will be described below with reference to the drawings. However, although various limitations that are technically preferable for carrying out the present invention are attached to the embodiments described below, the scope of the present invention is not limited to the following embodiments and illustrated examples.

<Hard disk drive>
FIG. 1 is a perspective view showing the configuration of a hard disk drive device 1. As shown in FIG. The hard disk drive device 1 includes a case 2, a spindle motor 3, a recording disk 4, a bearing device 5, and a cover 6.

The case 2 has the shape of a substantially rectangular parallelepiped box with an open bottom on one side. Inside the case 2, a spindle motor 3, a recording disk 4, and a bearing device 5 are arranged. The spindle motor 3 rotatably supports a plurality of recording disks 4. The plurality of recording disks 4 are supported by the spindle motor 3 so that their respective disk surfaces face each other. A gap is formed between each recording disk 4. The bearing device 5 swingably supports a plurality of swing arms 7 arranged in gaps between the recording disks 4 . A magnetic head 8 is provided at the tip of the swing arm 7. The magnetic head 8 is a member that applies magnetism to the recording disk 4 or reads magnetism from the recording disk 4 . The cover 6 is a plate-shaped member that closes the open surface of the case 2. The cover 6 is sealed together with the case 2 by a sealing means to form a housing 9. An internal space S is formed inside the housing 9 . The internal space S is filled with air or helium gas, which has a lower density than air. Note that, in addition to air and helium gas, the internal space S may be filled with, for example, nitrogen gas or a mixed gas of helium and nitrogen.

When the spindle motor 3 rotates, the recording disk 4 also rotates. When the swing arm 7 swings in this state, the magnetic head 8 moves above the rotating recording disk 4. The magnetic head 8 applies magnetism to the recording disk 4 or reads magnetism from the recording disk 4 . In this way, the hard disk drive device 1 can record information on the recording disk 4 and read information recorded on the recording disk 4.

<Spindle motor>
Next, the detailed configuration of the spindle motor 3 will be explained.

(First embodiment)
FIG. 2 is a sectional view showing the configuration of the spindle motor 3. As shown in FIG. The spindle motor 3 includes a base plate 10, a shaft 20, a rotor 30, and a stator core 40. A support member of this spindle motor 3 is a shaft 20.

Here, as shown in FIG. 2 and the like, the direction parallel to the central axis of the shaft 20, which will be described later, is the axial direction, the direction around the central axis of the shaft 20 is the circumferential direction, and the direction perpendicular to the axial direction is the radial direction. Further, for the sake of explanation, the axial direction is taken as the up-down direction, and the rotor 30 side with respect to the shaft 20 is taken as the top, and the base plate 10 side is taken as the bottom.

The base plate 10 is a metal member and is the bottom part of the case 2. As shown in FIG. 3, a through hole 11 and a circumferential wall portion 12 are formed in the base plate 10. As shown in FIG. The through hole 11 is a hole through which the end of the shaft 20 is inserted and fixed, and is provided so as to penetrate the base plate 10 in the axial direction. An annular groove 13 (an example of a groove) is provided in the inner peripheral surface 11A of the through hole 11. The annular grooves 13 are formed in the inner peripheral surface 11A in the circumferential direction, and are formed in two rows spaced apart in the axial direction. Note that the annular grooves 13 may be formed in only one row on the inner circumferential surface 11A, or may be formed in three or more rows spaced apart in the axial direction. As shown in FIG. 5, an epoxy electrodeposition coating film 14 (an example of a resin electrodeposition coating film) is formed in the two annular grooves 13. The circumferential wall portion 12 is formed in an annular shape so as to be concentric with the through hole 11 when viewed in the axial direction. The diameter of the circumferential wall portion 12 is larger than the diameter of the through hole 11.

The shaft 20 is a metal member formed in the shape of a cylindrical rod. FIG. 4 is a side view of the shaft 20. A through-hole insertion part 201, a first attachment part 202, and a second attachment part 203 are formed in the shaft 20 in this order from the end (lower side in FIG. 4). Each part is spaced apart in the axial direction. The outer diameter of the through-hole insertion portion 201 is smaller than the inner diameter of the through-hole 11.

The through-hole insertion part 201 is inserted so that the outer circumferential surface 201B of the through-hole insertion part 201 and the inner circumferential surface 11A of the through-hole 11 (see FIG. 3) face each other, and are joined with adhesive (see FIG. 2). . Note that the outer diameter of the through-hole insertion part 201 may be made larger than the inner diameter of the through-hole 11, and the through-hole insertion part 201 may be fitted into the through-hole 11 by press fitting and bonded with an adhesive.

The lower conical bearing member 21 is fixed to the first attachment part 202, and the upper conical bearing member 22 is fixed to the second attachment part 203 (see FIG. 2). The lower conical bearing member 21 and the upper conical bearing member 22 have conical outer surfaces, and the conical outer surfaces face outward in the radial direction.

The rotor 30 (an example of a rotating part) is a member attached to the shaft 20. The rotor 30 has a sleeve 31 and a hub 32. The sleeve 31 has a shaft insertion hole 310 into which the shaft 20 is inserted. The shaft insertion hole 310 has a lower conical inner surface 311 and an upper conical inner surface 312 at the lower and upper ends. The lower conical inner surface 311 faces the lower conical bearing member 21 with a small gap therebetween. The upper conical inner surface 312 faces the upper conical bearing member 22 through a small gap. A hub 32 is fixed to the outside of the sleeve 31 in the radial direction.

The minute gap between the lower conical bearing member 21 and the lower conical inner surface 311 and the minute gap between the upper conical bearing member 22 and the upper conical inner surface 312 are each filled with lubricating oil. Further, at least one of the lower conical inner surface 311 and the outer conical surface of the lower conical bearing member 21 and at least one of the upper conical inner surface 312 and the outer conical surface of the upper conical bearing member 22 are provided with dynamic pressure generating grooves. (not shown) is formed. As a result, a fluid dynamic pressure bearing 50 is formed.

The hub 32 has a disk portion 33, a cylindrical portion 34, and an outer edge portion 35. The disc portion 33 is a disc-shaped member, and a hub through hole 36 is provided at the center in the radial direction. The inner diameter of the hub through hole 36 is approximately equal to the outer diameter of the sleeve 31. The sleeve 31 is inserted into the hub through hole 36 such that the inner circumferential surface of the hub through hole 36 and the outer circumferential surface of the sleeve 31 face each other, and the hub 32 is fixed to the sleeve 31. The cylindrical portion 34 is a cylindrical member having a constant thickness in the radial direction, and extends in the vertical direction from the outer edge of the disk portion 33. An outer edge portion 35 is provided at the lower end of the lower cylindrical portion 34 . The outer edge portion 35 is a member that protrudes radially outward from the lower end portion of the cylindrical portion 34 when viewed in the axial direction, and extends in a flange shape over the entire circumference in the circumferential direction. A plurality of recording disks 4 are installed above the outer edge portion 35 and along the outer peripheral surface of the cylindrical portion 34 (see FIG. 1).

A yoke 37 and a ring magnet 38 are attached to the inner peripheral surface of the lower cylindrical portion 34. The yoke 37 is a cylindrical member that suppresses leakage of magnetic flux from the ring magnet 38. The yoke 37 is attached to the inner peripheral surface of the cylindrical portion 34 over the entire circumference in the circumferential direction. The ring magnet 38 is a cylindrical member, and is a permanent magnet magnetized in a state in which the polarity is reversed in the circumferential direction as viewed in the axial direction as N, S, N, S, . . . . The ring magnet 38 is attached to the inner peripheral surface of the yoke 37 over the entire circumference in the circumferential direction. The ring magnet 38 faces a stator core 40 around which a coil 41 (described later) is wound with a gap in the radial direction.

The stator core 40 is a member in which a plurality of annular electromagnetic steel plates are laminated in the axial direction when viewed in the axial direction. Stator core 40 extends along the outer circumferential surface of circumferential wall portion 12 and is fixed to the outer circumferential surface of circumferential wall portion 12 by a method such as adhesion. Further, the stator core 40 extends radially outward and has a plurality of pole teeth (salient poles) arranged along the circumferential direction. A coil 41 is wound around the pole teeth. When current flows through the coil 41, the stator core 40 generates magnetic flux.

<Spindle motor operation>
By passing current through the coil 41 and switching its polarity, the magnetic attraction force and the magnetic repulsion force generated between the ring magnet 38 and the pole teeth of the stator core 40 are switched. As a result, rotor 30 rotates about shaft 20.

As the rotor 30 rotates at high speed, lubrication is filled in the minute gap between the lower conical bearing member 21 and the lower conical inner surface 311 and the minute gap between the upper conical bearing member 22 and the upper conical inner surface 312. The oil is pressurized by the dynamic pressure generating groove. As a result, dynamic pressure is generated in the fluid dynamic pressure bearing 50. Due to the generated dynamic pressure, the sleeve 31 rotates while being supported by the shaft 20, the lower conical bearing member 21, and the upper conical bearing member 22 in a non-contact state. That is, the rotor 30 rotates while being supported by the shaft 20 in a non-contact state.

<Manufacturing method of spindle motor>
Next, a method for manufacturing the spindle motor 3 and adhesion of the base plate 10 and the shaft 20 according to the present embodiment will be described with reference to FIGS. 2 to 7.

FIG. 6 is a flowchart showing a method for manufacturing the spindle motor 3 according to the first embodiment. The manufacturing method consists of three steps from S11 to S13. The manufacturing method is performed by, for example, a working robot.

(S11)
S11 is a step of forming an annular groove 13 in the inner circumferential surface 11A of the through hole 11.

The working robot cuts the inner peripheral surface 11A of the through hole 11 in the circumferential direction to form an annular groove 13, as shown in FIG. 7(a). The annular grooves 13 are formed in two rows at intervals in the axial direction on the inner circumferential surface 11A. Although FIGS. 2 and 5 show an example in which the annular grooves 13 are formed in two rows in the axial direction on the inner circumferential surface 11A, they may be formed in one row or three or more rows.

(S12)
S12 is a step of forming an epoxy electrodeposition coating film 14 in the annular groove 13.

As shown in FIG. 7(b), the working robot performs electrodeposition coating on the inner peripheral surface 11A and the annular groove 13, and applies epoxy electrodeposition on the inner peripheral surface 11A and the surface of the annular groove 13. A coating film 14 is formed. Here, electrodeposition coating is one of the coating methods in which paint is applied to the surface of an object. Specifically, a metal object is placed in an aqueous solution containing a water-soluble paint containing positive or negative ions, the paint is applied to the metal surface by passing electricity, and the paint is then washed with water, dried, heated, etc. The paint adheres to the surface of the metal object. Here, the paint used in this embodiment is an epoxy resin paint. Note that an acrylic resin paint may be used as the electrodeposition coating, and an acrylic electrodeposition coating film (an example of a resin electrodeposition coating film) may be formed instead of the epoxy electrodeposition coating film 14.

After the epoxy electrodeposition coating film 14 is fixed on the inner peripheral surface 11A and the surface of the annular groove 13, the working robot applies the epoxy electrodeposition coating film 14 only on the annular groove 13, as shown in FIG. 7(c). The inner circumferential surface 11A is cut to remove the epoxy electrodeposition coating film 14 from the inner circumferential surface 11A.

(S13)
S13 is a step of inserting the shaft 20 into the through hole 11 and joining the shaft 20 to the base plate 10 with an adhesive.

The work robot applies adhesive to at least one of the outer circumferential surface 201B of the through-hole insertion portion 201 of the shaft 20 and the inner circumferential surface 11A of the through-hole 11. The adhesive applied here is an epoxy adhesive or an acrylic adhesive. Then, the working robot inserts the shaft 20 into the through hole 11 from above the through hole 11 so that the outer circumferential surface 201B and the inner circumferential surface 11A face each other. As the work robot inserts the shaft 20, the adhesive applied to the outer peripheral surface 201B and the inner peripheral surface 11A is pushed out into the annular groove 13. Since the epoxy electrodeposition coating film 14 is formed on the surface of the annular groove 13, the adhesive pushed out into the annular groove 13 is mixed with the epoxy electrodeposition coating film 14, as shown in FIG. 7(d). Contact. The work robot stops inserting the shaft 20 when the lower end of the shaft 20 reaches the lower end of the inner peripheral surface 11A.

After the step S13 is completed, the adhesive is cured by leaving at room temperature, heating, or the like. As the adhesive hardens, the base plate 10 and shaft 20 are fixed. That is, the base plate 10 and the shaft 20 are joined with adhesive.

Note that in this embodiment, the base plate 10 and the shaft 20 are joined with adhesive, but the outer diameter of the through-hole insertion part 201 of the shaft 20 is made larger than the inner diameter of the through-hole 11, so that the through-hole insertion part 201 may be fitted into the through hole 11 by press-fitting, and may also be joined using an adhesive.

<Effect>
In the above embodiment, the spindle motor 3 includes a base plate 10 having a through hole 11, a support member inserted into the through hole 11, a rotor 30 rotatably supported with respect to the support member, and an outer peripheral surface of the support member. It includes an annular groove 13 provided on the inner circumferential surface 11A of the opposing through hole 11, and an epoxy electrodeposition coating film 14 formed in the annular groove 13.

Further, the support member of the spindle motor 3 according to the present embodiment is a columnar shaft 20 having an outer circumferential surface 201B, and the outer circumferential surface 201B is fixed to the inner circumferential surface 11A, and the rotor 30 rotates around the shaft 20. Possibly supported.

It is known that intermolecular forces act more strongly between the epoxy electrodeposition coating film 14 and the adhesive than on the processed surface of the metal material. According to the above configuration, since the epoxy electrodeposition coating film 14 is formed in the annular groove 13 provided on the inner peripheral surface 11A, the shaft 20 is inserted into the through hole 11, and the shaft 20 and the base plate 10 are separated. When these are bonded together using an adhesive, strong intermolecular forces act between the epoxy electrodeposition coating film 14 and the adhesive. As a result, base plate 10 and shaft 20 are more firmly joined. In other words, the bonding force between the base plate 10 and the shaft 20 is high.

Further, by firmly joining the base plate 10 and the shaft 20, the sealing performance between the base plate 10 and the shaft 20 is improved. As a result, gas is less likely to leak through the through hole 11.

Furthermore, by firmly joining the base plate 10 and the shaft 20, the shaft 20 can support a larger axial load.

Further, the hard disk drive device 1 according to this embodiment includes the spindle motor 3 described above.

According to this configuration, the hard disk drive device 1 includes the spindle motor 3 that can support a larger axial load, so the number of recording disks 4 supported by the spindle motor 3 can be increased. In other words, the recording capacity of the hard disk drive 1 can be increased. Since a larger axial load can be supported, the height of the housing 9 can be increased and the length of the shaft 20 in the axial direction can be increased. As a result, in a hard disk drive 1 in which the height of the casing 9 is between 3.81 cm (1.5 inches) and 5.08 cm (2.0 inches), more recording disks 4 can be mounted. can do.

Further, the hard disk drive device 1 according to the present embodiment further includes a housing 9, the spindle motor 3 is disposed within the housing 9, and the inside of the housing 9 is sealed.

According to such a configuration, the inside of the casing 9 is sealed and the spindle motor 3 is disposed in the internal space S, so that foreign substances such as dust are difficult to enter from the outside of the casing 9. As a result, the spindle motor 3 is less likely to fail.

Further, when the internal space S is filled with helium gas or the like having a lower density than air, the gas resistance in the internal space S is reduced, so that uneven rotation and vibration of the recording disk 4 are reduced. As a result, the recording disks 4 can be operated with higher precision, so the number of recording disks 4 mounted on the hard disk drive device 1 can be increased. In other words, the recording capacity of the hard disk drive 1 can be increased.

Further, the manufacturing method of the spindle motor 3 configured by attaching the shaft 20 to the base plate 10 having the through hole 11 in the above embodiment includes a step of providing an annular groove 13 on the inner circumferential surface 11A of the through hole 11, 13, and a step of inserting the shaft 20 into the through hole 11 and joining the shaft 20 to the base plate 10 with an adhesive.

According to this method, the annular groove 13 in which the epoxy electrodeposition coating film 14 is formed is provided in the through hole 11 . By inserting the shaft 20 into such a through hole 11 and joining it with an adhesive, the base plate 10 and the shaft 20 can be firmly joined.

(Second embodiment)
Next, a spindle motor 3 whose supporting member is a bearing sleeve will be described.

FIG. 8 is a sectional view showing the configuration of the spindle motor 3. As shown in FIG. The spindle motor 3 includes a stationary part 402 and a rotating part 403 that rotates with respect to the stationary part 402.

<Stationary part>
Stationary portion 402 includes a base plate 410, a bearing sleeve 420, and a stator core 440.

The base plate 410 is a metal member and is the bottom part of the case 2. As shown in FIGS. 8 and 9, the base plate 410 is formed with a through hole 411, a circumferential groove portion 412, and a circumferential wall portion 413. The through hole 411 is a hole for fixing the bearing sleeve 420, and is provided to penetrate the base plate 410 in the axial direction. The inner diameter of the through hole 411 is approximately the same as or larger than the outer diameter of the bearing sleeve 420. An annular groove 414 is provided in the inner peripheral surface 411A of the through hole 411. The annular grooves 414 are formed in the inner peripheral surface 411A in the circumferential direction, and are formed in two rows spaced apart in the axial direction. Note that the annular grooves 414 may be formed in only one row on the inner circumferential surface 411A, or may be formed in three or more rows spaced apart in the axial direction. As shown in FIG. 10, an epoxy electrodeposition coating film 415 is formed in the two annular grooves 414. The circumferential groove portion 412 is formed on the outer side of the through hole 411 in the radial direction. The circumferential groove portion 412 is an annular groove provided coaxially with the center axis of the through hole 411 . Further, the circumferential wall portion 413 is formed as an annular wall portion that protrudes upward in the axial direction from the bottom surface of the circumferential groove portion 412 along the through hole 411. The circumferential wall portion 413 partitions the through hole 411 and the circumferential groove portion 412.

The bearing sleeve 420 is a cylindrical member that rotatably supports a shaft 430, which will be described later. The bearing sleeve 420 is inserted into the through hole 411 (see FIG. 8). In the state shown in FIGS. 8 and 10, the outer peripheral surface 420B of the bearing sleeve 420 faces the inner peripheral surface 411A of the through hole 411. The bearing sleeve 420 is fixed to the through hole 411 by an adhesive applied between the outer circumferential surface 420B and the inner circumferential surface 411A.

A shaft 430 is disposed inside the bearing sleeve 420. The inner circumferential surface 420A of the bearing sleeve 420 surrounds the outer circumferential surface 430B of the shaft 430, and the inner circumferential surface 420A and the outer circumferential surface 430B face each other with a small gap in between. This minute gap is filled with lubricating oil (not shown). A radial dynamic pressure generating groove 431 is provided in at least one of the inner circumferential surface 420A and the outer circumferential surface 430B. In the embodiment shown in FIG. 8, the radial dynamic pressure generating grooves 431 are formed in a continuous row in the circumferential direction on the inner circumferential surface 420A, and are formed in two rows spaced apart in the axial direction.

Furthermore, a large-diameter recess 423 that opens downward and a small-diameter recess 424 that opens upward from the top surface of the large-diameter recess 423 are formed on the lower end side of the bearing sleeve 420.

A counter plate 422 is attached to the large diameter recess 423 . The counter plate 422 is a disc-shaped lid that closes the small diameter recess 424 and the large diameter recess 423 from the lower end side of the bearing sleeve 420. The counter plate 422 is circular, and its outer diameter is approximately equal to the inner diameter of the large diameter recess 423. Further, the thickness of the counter plate 422 in the axial direction is approximately equal to the depth of the large diameter recess 423. The counter plate 422 is fixed to the bearing sleeve 420 without any gaps by press fitting, adhesion, welding, or the like, and closes the large diameter recess 423 and the small diameter recess 424.

The stator core 440 is a member in which a plurality of annular electromagnetic steel plates are laminated in the axial direction when viewed in the axial direction. Stator core 440 is disposed inside circumferential groove 412 and fixed to the outer circumferential surface of circumferential wall 413 by a method such as adhesion. Further, stator core 440 extends radially outward and has a plurality of pole teeth (salient poles) arranged along the circumferential direction. A coil 441 is wound around the pole teeth. When current flows through coil 441, stator core 440 generates magnetic flux.

<Rotating part>
The rotating section 403 includes a shaft 430, a rotor hub 450, and a rotor magnet 460.

The shaft 430 is a columnar member that serves as the rotation axis of the spindle motor 3, and is arranged inside the bearing sleeve 420. Further, the upper end of the shaft 430 protrudes from the bearing sleeve 420. Note that the radial dynamic pressure generating groove 431 may be provided not on the inner circumferential surface 420A of the bearing sleeve 420 but on a portion of the outer circumferential surface 430B of the shaft 430 that faces the inner circumferential surface 420A. A thrust plate 421 is attached to the lower end of the shaft 430.

The thrust plate 421 is an annular flange member that expands in the radial direction when viewed in the axial direction. The thrust plate 421 is fixed to the shaft 430 by being press-fitted into the shaft 430 or bonded with an adhesive. Thrust plate 421 is arranged in small diameter recess 424 . By disposing the thrust plate 421 between the lower surface 424C of the bearing sleeve 420 formed in the small diameter recess 424 and the counter plate 422, the thrust plate 421 and the shaft 430 are prevented from moving in the axial direction. The outer diameter of the thrust plate 421 is smaller than the inner diameter of the small diameter recess 424. Further, the axial thickness of the thrust plate 421 is thinner than the axial depth of the small diameter recess 424 .

In the state shown in FIGS. 8 and 10, the upper surface of the thrust plate 421 and the lower surface 424C face each other with a small gap in between. Further, the lower surface of the thrust plate 421 and the upper surface of the counter plate 422 face each other with a small gap in between. These minute gaps are filled with lubricating oil (not shown).

A thrust dynamic pressure generating groove is provided on at least one of the upper surface of the thrust plate 421 and the lower surface 424C of the bearing sleeve 420 (the upper surface of the thrust plate 421 in this embodiment). Further, a thrust dynamic pressure generating groove is also provided on at least one of the lower surface of the thrust plate 421 and the upper surface of the counter plate 422 (in the present embodiment, the lower surface of the thrust plate 421).

Rotor hub 450 is attached to the upper end of shaft 430 and rotates with shaft 430. The rotor hub 450 has a disk portion 451, a cylindrical portion 452, and an outer edge portion 453. The disc portion 451 is a disc-shaped member that is disposed above the bearing sleeve 420 and is coaxial with the central axis of the shaft 430 when viewed in the axial direction. A through hole 454 is provided in the center of the disc portion 451. The disk portion 451 is fixed to the shaft 430 by fixing the upper end of the shaft 430 to the through hole 454 by press fitting, adhesion, or the like. Note that the lower surface of the disc portion 451 and the upper surface of the bearing sleeve 420 face each other with a gap between them. The cylindrical part 452 is a cylindrical member having a constant thickness in the radial direction, and extends downward from the outer edge of the lower surface of the disc part 451. The inner diameter of the cylindrical portion 452 is larger than the outer diameter of the bearing sleeve 420, and the inner circumferential surface and the outer circumferential surface 420B of the cylindrical portion 452 face each other with a gap between them. The outer diameter of the cylindrical portion 452 is the same as the outer diameter of the disk portion 451. The outer edge portion 453 is a member that protrudes radially outward at the lower end of the cylindrical portion 452 when viewed in the axial direction, and extends in a flange shape over the entire circumference in the circumferential direction.

The rotor magnet 460 is an annular member having a magnetic pole structure in which the polarity is reversed as N, S, N, S, . . . along the circumferential direction when viewed in the axial direction. In this embodiment, the rotor magnet 460 is attached to the inner peripheral surface of an annular yoke 461 attached to the lower end of the outer edge portion 453. Rotor magnet 460 is located at approximately the same position as stator core 440 in the axial direction, and located between stator core 440 and the inner peripheral surface of circumferential groove 412 in radial direction. Yoke 461 suppresses leakage of magnetic flux from rotor magnet 460. Note that the cylindrical portion 452 or the outer edge portion 453 is disposed between the stator core 440 and the inner circumferential surface of the circumferential groove portion 412, and the annular yoke 461 is disposed between the inner circumferential surface of the cylindrical portion 452 or the inner circumferential surface of the outer edge portion 453. It may be attached. In that case, rotor magnet 460 is attached to the inner peripheral surface of yoke 461 so as to face stator core 440 .

<Spindle motor operation>
When the coil 441 is energized, the magnetic attraction force and the magnetic repulsion force generated between the magnetic poles of the rotor magnet 460 and the pole teeth of the stator core 440 are switched. As a result, the rotating section 403 rotates with respect to the stationary section 402 using the shaft 430 as the rotation axis.

Shaft 430 rotates relative to bearing sleeve 420. At this time, the lubricating oil is pressurized by the radial dynamic pressure generating groove 431, so that dynamic pressure is generated in the lubricating oil. Due to the generated dynamic pressure, the shaft 430 is supported in a radial direction with respect to the bearing sleeve 420 in a non-contact state.

As shaft 430 rotates, thrust plate 421 rotates relative to bearing sleeve 420 and counterplate 422. At this time, a thrust dynamic pressure generating groove provided on at least one of the upper surface or the lower surface 424C of the thrust plate 421 and a thrust dynamic pressure generation groove provided on at least one of the lower surface of the thrust plate 421 or the upper surface of the counter plate 422 Dynamic pressure is generated by pressurizing the lubricating oil with the generation groove. Due to the generated dynamic pressure, the thrust plate 421 is supported in the axial direction without contacting the bearing sleeve 420 and the counter plate 422.

<Manufacturing method of spindle motor>
Next, a method of manufacturing the spindle motor 3 according to the present embodiment and adhesion of the base plate 410 and the bearing sleeve 420 will be described with reference to FIGS. 8 to 12.

FIG. 11 is a flowchart showing a method for manufacturing the spindle motor 3 according to the second embodiment. The manufacturing method includes three steps from S111 to S113. The manufacturing method is performed by, for example, a working robot.

(S111)
S111 is a step of forming an annular groove 414 in the inner peripheral surface 411A of the through hole 411.

The work robot cuts the inner circumferential surface 411A of the through hole 411 in the circumferential direction to form an annular groove 414, as shown in FIG. 12(a). Two rows of annular grooves 414 are formed on the inner circumferential surface 411A at intervals in the axial direction. Although FIGS. 8 and 10 show an example in which the annular grooves 414 are formed in two rows in the axial direction on the inner circumferential surface 411A, they may be formed in one row, or three or more rows.

(S112)
S112 is a step of forming an epoxy electrodeposition coating film 415 in the annular groove 414.

As shown in FIG. 12(b), the working robot performs electrodeposition coating on the inner circumferential surface 411A and the annular groove 414, and coats the inner circumferential surface 411A and the annular groove 414 with an epoxy electrodeposited coating film 415. Form. Here, the paint used as the epoxy electrodeposition coating film 415 in this embodiment is an epoxy resin paint. Note that an acrylic resin paint may be used as the electrodeposition coating, and an acrylic electrodeposition coating film may be formed instead of the epoxy electrodeposition coating film 415.

After the epoxy electrodeposition coating film 415 on the inner circumferential surface 411A and the surface of the annular groove 414 is fixed, the working robot applies the epoxy electrodeposition coating film 415 only on the annular groove 414, as shown in FIG. 12(c). The inner circumferential surface 411A is cut to remove the epoxy electrodeposition coating film 415 from the inner circumferential surface 411A.

(S113)
S113 is a step of inserting the bearing sleeve 420 into the through hole 411 and joining the bearing sleeve 420 to the base plate 410 with adhesive.

The work robot applies adhesive to at least one of the outer peripheral surface 420B of the bearing sleeve 420 and the inner peripheral surface 411A of the through hole 411. The adhesive applied here is an epoxy adhesive or an acrylic adhesive. Then, the working robot inserts the bearing sleeve 420 into the through hole 411 from above the through hole 411 so that the outer peripheral surface 420B and the inner peripheral surface 411A face each other. As the working robot inserts the bearing sleeve 420, the adhesive applied to the outer circumferential surface 420B and the inner circumferential surface 411A is pushed out into the annular groove 414. Since the epoxy electrodeposition coating film 415 is formed on the surface of the annular groove 414, the adhesive pushed out into the annular groove 414 is mixed with the epoxy electrodeposition coating film 415, as shown in FIG. 12(d). Contact. The work robot stops inserting the bearing sleeve 420 when the lower end of the bearing sleeve 420 reaches the lower end of the inner peripheral surface 411A.

After the step S113 is completed, the adhesive is cured by leaving at room temperature, heating, or the like. As the adhesive hardens, base plate 410 and bearing sleeve 420 are fixed. That is, the base plate 410 and the bearing sleeve 420 are bonded together using an adhesive.

Note that in this embodiment, the base plate 410 and the bearing sleeve 420 are joined with adhesive, but the outer diameter of the bearing sleeve 420 is made larger than the inner diameter of the through hole 411, and the bearing sleeve 420 is inserted into the through hole by press fitting. 411 and may be joined using an adhesive.

<Effect>
The support member of the spindle motor 3 according to this embodiment is a cylindrical bearing sleeve 420, the rotating part 403 has a columnar shaft 430 extending in the axial direction, and the bearing sleeve 420 rotatably supports the shaft 430. .

According to the above configuration, since the epoxy electrodeposition coating film 415 is formed in the annular groove 414 provided on the inner peripheral surface 411A, the bearing sleeve 420 is inserted into the through hole 411 and the bearing sleeve 420 and When bonding the base plate 410 with an adhesive, strong intermolecular forces act between the epoxy electrodeposition coating film 415 and the adhesive. As a result, base plate 410 and bearing sleeve 420 are more firmly joined. In other words, the bonding force between the base plate 410 and the bearing sleeve 420 is high.

Moreover, since the base plate 410 and the bearing sleeve 420 are firmly joined, the sealing performance between the base plate 410 and the bearing sleeve 420 is improved. As a result, gas is less likely to leak through the through hole 411.

Furthermore, by firmly joining the base plate 410 and the bearing sleeve 420, the shaft 430 can support a larger axial load.

In addition, the manufacturing method of the spindle motor 3 configured by attaching the bearing sleeve 420 to the base plate 410 having the through hole 411 in the above embodiment includes a step of providing an annular groove 414 in the inner circumferential surface 411A of the through hole 411; The steps include forming an epoxy electrodeposition coating film 415 in the groove 414, inserting the bearing sleeve 420 into the through hole 411, and joining the bearing sleeve 420 to the base plate 410 with an adhesive.

According to such a method, an annular groove 414 in which an epoxy electrodeposition coating film 415 is formed is provided in the through hole 411 . By inserting the bearing sleeve 420 into such a through hole 411 and joining it with an adhesive, the base plate 410 and the bearing sleeve 420 can be firmly joined.

DESCRIPTION OF SYMBOLS 1... Hard disk drive device, 3... Spindle motor, 9... Housing, 10, 410... Base plate, 11, 411... Through hole, 11A, 411A... Inner peripheral surface, 13, 414... Annular groove (groove), 14, 415 ...Epoxy electrodeposition coating film (resin electrodeposition coating film), 20...Shaft, 30...Rotor (rotating part), 201B, 420B...Outer peripheral surface, 403...Rotating part, 420...Bearing sleeve, 430...Shaft

Claims (6)

a base plate having a through hole;
a support member inserted into the through hole;
a rotating part rotatably supported with respect to the support member;
an annular groove provided in an inner circumferential surface of the through hole facing an outer circumferential surface of the support member;
a resin-based electrodeposition coating film formed in the groove;
A spindle motor equipped with. The support member is a columnar shaft having the outer peripheral surface,
The spindle motor according to claim 1, wherein the outer circumferential surface is fixed to the inner circumferential surface, and the rotating section is rotatably supported around the shaft. The support member is a cylindrical bearing sleeve,
The spindle motor according to claim 1, wherein the rotating part has a columnar shaft extending in the axial direction, and the bearing sleeve rotatably supports the shaft. A hard disk drive device comprising the spindle motor according to any one of claims 1 to 3. The hard disk drive further includes a housing,
5. The spindle motor according to claim 4, wherein the spindle motor is disposed within the casing, the inside of the casing is sealed, and the height of the casing is 3.81 cm or more and 5.08 cm or less. hard disk drive. A method for manufacturing a spindle motor comprising a support member attached to a base plate having a through hole, the method comprising:
providing an annular groove on the inner peripheral surface of the through hole;
forming a resin-based electrodeposition coating film in the groove;
inserting the support member into the through hole and bonding the support member to the base plate with an adhesive;
A method of manufacturing a spindle motor, including:

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