JP2001041253A - Spindle motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase and stabilize adhesive strength between a shaft and a bearing by providing a first adhesive holding groove for holding adhesive for fixing the bearing and a second adhesive holding groove with width smaller than that of the first adhesive holding groove. SOLUTION: For bonding a shaft 3 to a bearing 4, outer peripheries 31, 32 of the shaft 3 are coated with adhesives, and then the bearing 4 is inserted outside the shaft 3. Most of applied adhesives are held in first adhesive holding grooves 311, 321, and bulging-out partial adhesives go to second adhesive holding grooves 312, 322 and are held there. After hardening the adhesive, the inner peripheral surfaces 41, 42 of the bearing 4 and adhesive outer peripheries 31, 32 of the shaft 3 are bonded and fixed to each other with the adhesive held in the first adhesive holding grooves 311, 321 and the adhesive held in the second adhesive holding grooves 312, 322. Therefore, the bearing 4 is fixed to the shaft 3 more strongly and stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spindle motor having a bearing, and more particularly, to a spindle motor for driving a hard disk rotation, in which a rotating hub and a bearing are fixed to each other and a fixed shaft and the bearing are fixed to each other by an adhesive. In this case, it relates to the structure of the bonding surface.

[0002]

2. Description of the Related Art The structure of a spindle motor for rotating a hard disk according to the prior art will be described with reference to FIGS.

In a side sectional view of a spindle motor for driving a hard disk according to the prior art shown in FIG. 5, a spindle motor (100) includes a base (110), a bearing (4), and a bearing (4). The rotor (12) rotatably attached to the base (110)
0).

[0004] A stator core (1) is adhered to the base (110). The stator core (1) has a plurality of salient poles (not shown), and a driving coil (2) is wound around each salient pole.

The shaft (3) is press-fitted to the base (110). The shaft (3) has a pair of bearings (4)
The hub (6) is rotatably mounted via the.

The outer periphery of the shaft (3) and the inner periphery of the bearing (4), and the inner periphery of the hub (6) and the outer periphery of the bearing (4) are fixed with an adhesive.

A cylindrical rotor yoke (7) and a magnet (8) are fixed to the lower surface (the surface facing the base portion (110)) of the flange portion (61) formed at the lower portion of the hub (6). I have.

A drive coil (2) wound around a stator core (1) mounted on a base (110) is connected to a control circuit (not shown) via a connection board (9).

A salient pole portion (not shown) of the stator core (1) and the magnet (8) are opposed at a predetermined interval, and the spindle motor (100) is operated in accordance with a current applied by a control circuit.
To give a turning force.

Next, a method for fixing the bearing (4) of the spindle motor according to the prior art will be described with reference to FIG.

FIG. 6A is a sectional view of a main part for explaining a method of fixing a bearing (4) of a conventional spindle motor. FIG.
It is an enlarged view centering on the adhesion surface in (A).

In FIGS. 6A and 6B, the bearing (4) and the shaft (3) are fixed to each other by fixing the inner peripheral surfaces (41) and (42) of the bearing (4) to the shaft ( This is performed by bonding the outer peripheral portions (31) and (32) of (3) with an adhesive.

[0013] Two bonded outer peripheral portions (31) of the shaft (3)
An adhesive holding groove (311) (321) for holding an adhesive is formed in each of the (32), and the bearing (4) is formed by the adhesive force of the adhesive (10) held therein. ) And the shaft (3) are fixed to each other.

[0014]

The recording density of a hard disk recording device has been improved year by year, and a disk drive motor mounted on the device is required to have improved mechanical rigidity.

In the spindle motor according to the prior art shown in FIG. 5, the base (110) and the shaft (3), and the hub (6) and the bearing (4) are fixed by press-fitting and bonding. The fixing strength is improved as compared with the fixing by only the fixing.

On the other hand, the shaft (3) and the bearing (4) are fixed only by bonding. The reason is that when the inner ring of the bearing (4) is fixed to the shaft (3), the inner ring portion (shaft (4) of the bearing (4) is used for the purpose of loosening the internal structure (balls and ball bearings) of the bearing (4). 3) Side that touches)
This is because it is necessary to bond under preload in the axial direction.

That is, in order to loosen the bearing (4) by applying a preload to the bearing (4) and to realize smooth rotation of the bearing (4), the inner peripheral surface (4) of the bearing (4) is required.
1) It is necessary to precisely drive the relative position between (42) and the outer peripheral portions (31) and (32) of the shaft, and when the shaft (3) is press-fitted into the bearing (4), such precise position is required. This is because it is difficult to keep track of the position.

As described above, the shaft (3) and the bearing (4)
Is fixed only by bonding, and the fixing strength greatly depends on the bonding strength.

On the other hand, in the spindle motor according to the prior art described above, there are the following problems that become obstacles when trying to increase the above-mentioned adhesive strength.

That is, the radial gap at the bonding surface between the bearing (4) and the shaft (3) is at most several microns in order to realize high assembling accuracy of the motor. During the bonding operation, the outer peripheral portion (3) of the shaft (3) is bonded.
1) When the bearing (4) is extrapolated after applying the adhesive to (32), most of the adhesive cannot be held in the gap in the bonding surface between the bearing (4) and the shaft (3).
Except for the amount held in the adhesive holding grooves (311) and (321) in the enlarged cross-sectional view of the bonding portion shown in (B), it escapes to the outside of the bonding surface (10F).

Therefore, the adhesive holding grooves (311) (32)
Most of the adhesive fixing between the shaft (3) and the bearing (4) is performed only by the adhesive held in (1). For this reason, there is a possibility that the adhesive strength in the adhesive holding grooves (311) and (321) may vary depending on the degree of accumulation (amount or unevenness) of the adhesive.

In order to improve the adhesive strength, the width of the adhesive holding grooves (311) and (321) may be increased, or the adhesive holding grooves having the same shape may be formed in the outer peripheral portion of the shaft (3). 31) If it is attempted to provide a plurality in (32),
The following problems occur. That is, with such a configuration, the area of the bonded outer peripheral portions (31) and (32) in contact with the bearing (4) is greatly reduced, and necessary spindle motors such as the concentricity of the shaft (3) and the hub (6). (10
There is a problem that the assembly accuracy of 0) is reduced. Therefore, it was difficult to realize.

If the bonding strength between the shaft (3) and the bearing (4) is insufficient, in the worst case, the bearing (4) and the shaft (3) may be broken (peeling off at the bonding surface),
In that case, the preload applied to the bearing (4) disappears, the runout accuracy during rotation of the hub (6) deteriorates, and a head crash may occur.

The present invention has been made in view of the above circumstances, and has a spindle motor (100) having a large and stable adhesive strength between a shaft (3) and a bearing (4).
Is provided.

[0025]

In order to solve the above-mentioned problems, the present invention provides a base (110), a shaft member (3) standing and fixed to the base (110), and an inner peripheral part. Bearing (4) having an outer peripheral portion, a hub (6) rotatably mounted on the shaft member (3) via the bearing (4), and a magnet (8) mounted on the hub (6). ) And a stator core (1) mounted on the base portion (110) in opposition to the magnet (8), in the spindle motor (100) facing the bearing (4) of the hub (6). An adhesive (10) for fixing the bearing (4) is fixed to the inner peripheral surface and / or the outer peripheral surface (31) (32) of the shaft member (3) facing the bearing (4). One adhesive holding groove (311) (321) And a second adhesive holding groove (312) (322) having a smaller width than the first adhesive holding groove (311) (321). I do.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS.
A spindle motor for a hard disk, which is an embodiment of the present invention, will be described.

FIG. 1 is a structural diagram of a spindle motor according to the present embodiment. In the following description, the same reference numerals are given to components having the same functions as those of the spindle motor according to the related art described above with reference to FIGS. 5 and 6, and the description is omitted without repeating the same description. There are points.

The spindle motor of this embodiment shown in FIG. 1 is different from the spindle motor of the prior art shown in FIG. 5 only in the shape of the bonding surface of the shaft (3) facing the bearing (4). I do. The details of the difference will be described below with reference to FIG.

FIGS. 2A and 2B are a cross-sectional view and an enlarged view for explaining the bonding between the bearing (4) and the shaft (3) of the spindle motor according to the present embodiment.

In FIGS. 2A and 2B, the outer peripheral portion (3) of the shaft (3) facing the bearing (4) is shown.
1) (32) The first adhesive holding grooves (311) and (321) for holding the adhesive on each surface, and the width is smaller than the first adhesive holding grooves (311) and (321). ,
Second adhesive holding grooves (312) and (322) are formed.

When the shaft (3) formed as described above is bonded to the bearing (4), an adhesive is applied to the bonding outer peripheral portions (31) and (32) of the shaft (3), and then the bearing (4). 4) is extrapolated to axis (3). Most of the applied adhesive is held in the first adhesive holding grooves (311) and (321), and a part of the adhesive that protrudes therefrom is transferred to the second adhesive holding grooves (312) and (322). Go to) and be held there.

After the adhesive is cured, the inner peripheral surfaces (41) and (42) of the bearing (4) and the outer peripheral portion (31) of the shaft (3) are bonded.
(32) means the first adhesive holding groove (311) (32)
The adhesive held in 1) and the second adhesive holding groove (31)
2) Adhesively fixed with the adhesive held in (322). Therefore, the first adhesive holding grooves (311) (32)
The bearing (4) and the shaft (3) are firmly and stably fixed compared to the spindle motor according to the related art having only 1).

FIG. 3 shows a conventional spindle motor having the structure shown in FIG. 6 and a spindle motor according to the present embodiment having the structure shown in FIG. 2 showing the bonding strength between the shaft (3) and the bearing (4). It is the data compared in the motor.

In FIG. 3, the frequency distribution is shown with the axis-pulling strength, which is the strength in the axial direction at which the adhesive breaks after the adhesive is cured, on the vertical axis and the frequency on the horizontal axis. FIG. 3A is a frequency distribution graph of the conventional spindle motor, and FIG. 3B is a frequency distribution graph of the spindle motor of the present embodiment. According to FIG. 3, it is clear that the spindle motor according to the present embodiment has improved shaft removal strength as compared with the spindle motor according to the related art.

By the way, the first adhesive holding groove (311)
If another groove having the same width as (321) is formed on the outer peripheral surface of the shaft (3), the contact area between the shaft (3) and the inner ring of the bearing (4) is reduced, which affects the assembling accuracy of the spindle motor. That was explained earlier. However, the above-described second adhesive holding groove (31)
2) and (322) are the first adhesive holding grooves (311) and (3).
Since it can be formed with a width smaller than that of 21), the above-described problem does not occur. The reason will be described below.

In the structure of the present embodiment shown in FIG.
The first adhesive holding groove (311) (321) is
It has a function to hold much of the adhesive applied first to the tank like a tank, and to allow the overflowing adhesive to move to other holding grooves, so make the width and depth large enough for it. There must be. However, the second adhesive holding grooves (312) and (322) have an inner peripheral surface (41) of the bearing (4) where the adhesive moved from the other stays there.
It suffices if a sufficient amount of adhesive can be held to adhesively fix the (42) and the outer peripheral portions (31) and (32) of the shaft (3). Therefore, the second adhesive holding groove (312) (32
The width and the depth of the second adhesive holding groove (311) (311)
21) can be a smaller value.

Next, in the present embodiment, an example in which the first adhesive holding grooves (311) (321) and the second adhesive holding grooves (312) (322) are formed in a shape different from that of FIG. Will be described with reference to FIG.

FIG. 4 shows the structure of the bonding surface of the shaft (3) facing the bearing (4) in the spindle motor of this embodiment shown in FIG. 1 which is different from the structure described above with reference to FIG. 4A is a cross-sectional view of a main part, and FIG. 4B is an enlarged view of the main part.
It is shown.

4 (A) and 4 (B), the outer peripheral portion (3) of the shaft (3) facing the bearing (4) is shown.
1) and (32) include a plurality of first adhesive holding grooves (31).
A plurality of second adhesive holding grooves (312) having different widths and depths from 1) and the first adhesive holding groove (312) are formed.

The adhesive applied to the outer peripheral portions (31) and (32) is held in the plurality of first adhesive holding grooves (311) and the plurality of second adhesive holding grooves (312), After curing, the adhesive (10) held in the holding grooves (311) (312) bonds and fixes the shaft (3) and the bearing (4).

With the structure of the bonding surface shown in FIG. 4, the number of points to be bonded and fixed, that is, the number of grooves holding the adhesive is shown in FIG.
Since it is possible to increase the number of structures, the effect of improving the bonding strength can be obtained. Further, the structure shown in FIG. 4 is provided with a plurality of first adhesive holding grooves (311) for holding and moving the adhesive to another place, instead of a single groove. Since the second adhesive holding groove (312) is provided adjacent to (311), the first adhesive holding groove (311) is connected to the second adhesive holding groove (31).
Since the transfer of the adhesive to 2) can be performed more smoothly, there is an effect of further stabilizing the adhesive strength between the shaft (3) and the bearing (4).

In the spindle motor of this embodiment described with reference to FIGS. 1 to 4, the first adhesive holding grooves (311) and (321) and the second adhesive holding groove (311)
12 and (322) have been described as being provided on the bonded outer peripheral portions (31) and (32) of the shaft (3) facing the bearing (4).

However, in practicing the present invention, the present invention is not limited to the above description, but may be applied to the inner peripheral surfaces (41) and (42) of the bearing (4) or the inner peripheral surfaces (41) and (42) of the bearing (4). ) And shaft (3) bonding outer peripheral portion (31)
The same effect can be obtained by providing the first adhesive holding groove and the second adhesive holding groove in both (32).

Further, according to the present invention, the first adhesive holding groove and the first adhesive holding groove are provided on the outer peripheral surface of the bearing (4) and / or the inner peripheral portion of the hub (6) which is opposed to the bearing (4). When the second adhesive holding groove having a width smaller than that of the adhesive holding groove is formed, the bonding strength between the bearing (4) and the hub (6) is improved, and the bonding strength is stabilized. Is what you do.

The reason why the above-mentioned effect is exhibited is the same as that of the embodiment of the present invention described above with reference to FIGS. That is, the adhesive is held in the first adhesive holding groove and the second adhesive holding groove, and the bearing (4) and the hub (6) are bonded and fixed by the held adhesive. Strength and stability are realized.

[0046]

As described in detail above, the spindle motor according to the present invention comprises a shaft (3) and a bearing (4).
This has the effect of improving the adhesive strength with the adhesive and stabilizing the adhesive strength. Further, the spindle motor according to the present invention has the effects of improving the bonding strength between the hub (6) and the bearing (4) and stabilizing the bonding strength.

[Brief description of the drawings]

FIG. 1 is a sectional view of a spindle motor according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the spindle motor according to one embodiment of the present invention.

FIG. 3 is a frequency graph for comparing the adhesive strength between the spindle motor according to one embodiment of the present invention and the spindle motor according to the related art.

FIG. 4 is a sectional view of a main part of another example of a spindle motor according to an embodiment of the present invention.

FIG. 5 is a sectional view of a spindle motor according to the related art.

FIG. 6 is a sectional view of a main part of a spindle motor according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator core 2 Coil 3 Axis 4 Bearing 5 Magnetic disk 6 Hub 7 Rotor yoke 8 Magnet 9 Connection board 10 Adhesive 10F Adhered adhesive 31 Adhesive outer peripheral part 32 Adhesive outer peripheral part 41 Bearing inner peripheral surface 42 Bearing inner peripheral surface 61 Flange 100 Spindle motor 110 Base part 120 Rotor part 311 First adhesive holding groove 312 Second adhesive holding groove 321 First adhesive holding groove 322 Second adhesive holding groove

Claims (1)

[Claims] 1. A base member, a shaft member standing and fixed to the base member, a bearing having an inner peripheral portion and an outer peripheral portion, and a hub rotatably mounted on the shaft member via the bearing. A spindle motor having a magnet mounted on the hub and a stator core mounted on the base member facing the magnet, wherein the inner peripheral surface of the hub facing the bearing and / or the shaft member has On the outer peripheral surface facing the bearing,
It has a first adhesive holding groove for holding an adhesive for fixing the bearing, and a second adhesive holding groove smaller in width than the first adhesive holding groove. Spindle motor.