JPH084777A - Dynamic pressure bearing assembling method - Google Patents

Abstract

PURPOSE:To inject a lubricant without mixing bubbles by stopping insertion of a shaft body for constant time when the lubricant around the shaft body strides over a thrust receiving surface and a thrust plate, uniformly distributing the lubricant in a range of the shaft body, and blocking up the insertion of the shaft body after this stopping time. CONSTITUTION:A shaft, a suspending part 20 fitted around this shaft 4 and a sleeve body 16 having a thrust receiving surface orthogonal to this are provided. A part of the shaft 4 is inserted in the suspending part 20 of the sleeve body 16, and a lubricant 25 is arranged around the shaft 4 at an inlet of this suspending part 20. Afterward, the shaft 4 is inserted in the suspending part 20, and when the lubricant 25 around the shaft 4 strides over the thrust receiving surface and a thrust plate 11, insertion of the shaft 4 is stopped for constant time, and the lubricant 25 is uniformly distributed around the shaft 4. After this stopping time, the insertion of the shaft 4 is resumed. Thereby, the lubricant 25 is injected without mixing bubbles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of assembling a dynamic pressure bearing in which a sleeve body can freely rotate relative to a shaft body through a lubricant.

[0002]

2. Description of the Related Art As devices such as personal computers become smaller and have higher capacities, spindle motors for driving recording media (eg, hard disks) incorporated therein are required to be smaller and more accurate. There is. Along with this, the bearings of spindle motors are required to be further downsized and have higher accuracy.

Conventionally, a ball bearing has been used as a bearing for a spindle motor. However, as the spindle motor is made smaller, especially as its outer diameter is reduced, a ball bearing having a smaller outer diameter suitable for it is used. However, when the motor is assembled, the inner and outer races are likely to be deformed, it is difficult to obtain sufficient rotation accuracy, and problems such as noise and vibration occur. Particularly, in the case of a spindle motor for driving a recording medium, high speed rotation is required as the outer diameter becomes smaller, so these problems are further promoted.

Therefore, mainly as a small-sized spindle motor, a rotary sleeve portion is provided on the inner peripheral side of the base portion of the rotor hub portion, and the rotary sleeve portion is externally fitted to the shaft body and is rotatably supported. A spindle motor having a radial bearing has been proposed.

A spindle motor for driving a magnetic disk, which employs this kind of dynamic pressure bearing, is constructed, for example, as shown in FIG. That is, in FIG. 1, a base member 1 forming a part of the magnetic disk drive is made of, for example, an aluminum alloy, and a boss portion 2 projecting in an annular shape is integrally formed at the center of the base member 1. . This boss 2
A hole 3 is formed in the hole, and a lower end 4a of a shaft (shaft body) 4 is fitted and fixed in the hole 3. Shaft 4
Is formed of an iron-based alloy material or the like.

A stator 5 is externally fitted and fixed to the outer periphery of the upper end portion of the boss portion 2 of the base member 1. The stator 5 is
It is composed of a stator core 6 formed by laminating a plurality of electromagnetic steel plates, and a coil 7 wound around the stator core 6. The flexible circuit board 8 is provided under the base member 1.
Are attached and fixed, and an end portion of the circuit board 8 is extended to the outside of the motor. The coil wire 9 drawn from the coil 7 is connected to the circuit board 8 through a hole 10 formed in the base member 1 and led out to the outside of the motor.

The upper end portion 4b of the shaft 4 fixed to the base member 1 is formed to have a reduced diameter, and a hole (not shown) is bored in the axial center portion of the shaft 4 so that a magnetic disk (not shown) is formed. It is screwed and fixed to the upper lid of the drive unit. Shaft 4
On the upper end 4b side, a thrust plate 11 is formed coaxially and coaxially with the shaft 4 and is formed so as to project outward in the radial direction over the entire circumference. Thrust bearing surfaces 12 and 13 that are orthogonal to the axis of the shaft 4 are formed substantially parallel to the upper and lower surfaces of the thrust plate 11, and the thrust bearing surfaces 12 and 13 are not shown in the drawing. Herringbone-shaped dynamic pressure grooves provided at predetermined intervals are formed in the circumferential direction. A groove 14 having a substantially V-shaped cross section is formed on the entire outer peripheral end surface of the thrust plate 11.

The rotor hub 15 which is rotatably supported on the shaft 4 is composed of a sleeve body 16, a hub 17, a rotor magnet 18 and a thrust cover 19.
The sleeve body 16 is formed of a copper-based alloy or the like, and has a cylindrical hanging portion 20, a cylindrical large-diameter peripheral wall 21 having a diameter larger than that of the hanging portion 20, and provided coaxially with the hanging portion 20. It is composed of an annular base portion 22 that connects the portion 20 and the large-diameter peripheral wall 21. On the inner peripheral surface of the hanging portion 20, herringbone-shaped dynamic pressure grooves arranged in the circumferential direction are provided in two upper and lower stages.

The inner peripheral surface of the hanging portion 20 of the sleeve body 16 and the outer peripheral surface of the shaft 4 are arranged so as to face each other along the axial direction with a slight clearance, and this clearance is filled with a lubricant such as oil. There is. As a result, the rotor hub 15 is supported by the dynamic pressure bearing in the radial direction with respect to the shaft 4. In FIG. 6, the dynamic pressure groove is provided on the sleeve body 16 side as the radial dynamic pressure bearing, but conversely, it may be provided on the shaft 4 side. The annular intermediate groove portion 4c formed on the shaft 4 faces between the upper and lower two-stage dynamic pressure grooves formed on the hanging portion 20, and is provided on the lower end portion side of the shaft 4 for preventing lubricant from flowing out. The annular groove 4d is
Corresponding to the vicinity of the lower end of the hanging portion 20, the inner surface of the hanging portion 20 is subjected to oil repellent treatment, and acts to prevent leakage of the lubricant.

The thrust cover 19 is substantially disk-shaped, and has a hole 23 at the center thereof, into which the reduced diameter upper end 4a of the shaft 4 is inserted. The thrust cover 19 is fixed to the sleeve body 16 on the outer peripheral side thereof. That is, the outer peripheral lower surface of the thrust cover 19 is placed on the annular base portion 22 of the sleeve body 16, and the outer peripheral surface of the thrust cover 19 and the upper inner peripheral surface of the large diameter peripheral wall 21 are held in contact with each other. In this state, the upper wall of the large-diameter peripheral wall 21 is swaged to the shaft side by plastic deformation, etc.
Are tightly fixed to the sleeve body 16.

At this time, the upper thrust receiving surface of the lower surface of the thrust cover 19 and the lower thrust receiving surface of the upper surface of the hanging portion 20 of the sleeve body 16 have a slight gap between them, and the thrust bearings above and below the thrust plate 11 are provided. Faces 12, 13
Are arranged so as to face each other, and the respective gaps are filled with a lubricant such as oil. Therefore, the upper thrust receiving surface of the thrust cover 19, the thrust bearing surface 12 of the thrust plate 11, and the thrust bearing surface 13 of the thrust plate 11.
A thrust dynamic pressure bearing means is constituted by the lower thrust receiving surface of the hanging portion 20. This restricts the position of the rotor hub 15 in the axial direction, and supports the rotary bearing in the axial direction by the dynamic pressure bearing. As a thrust dynamic pressure bearing, a dynamic pressure groove is provided on the upper thrust receiving surface of the lower surface of the thrust cover 19 and on the lower thrust receiving surface side of the upper surface of the hanging portion 20 in addition to the dynamic pressure groove provided on the thrust plate 11. May be.

A hub 17 made of an aluminum alloy or the like is fixed to the outer peripheral portion of the large-diameter peripheral wall 21 of the sleeve body 16, and an annular rotor magnet 18 is arranged on the inner periphery of the lower portion of the hub 17. . The rotor magnet 18 contacts the lower surface of the large-diameter peripheral wall 21 and is axially positioned, and is fixed to the hub 17 at a height corresponding to the stator 5. The magnetic disk not shown is the hub 17
It is fitted and mounted on the outer peripheral portion, is received by the collar portion 24 formed below, and is fixed by a clamping means (not shown).

By the way, in such a dynamic pressure bearing type spindle motor, in order to ensure smooth and highly accurate rotation, a radial dynamic pressure bearing portion and a thrust plate between the shaft 4 and the sleeve body 16 are provided. It is necessary to sufficiently spread the lubricant on each of the thrust dynamic pressure bearing portions between 11 and the sleeve body 16 and the thrust cover 19.

For this reason, conventionally, the lubricant is injected according to the procedure shown in FIG. 7, which shows each assembling process. Note that FIG. 7 shows the dynamic pressure bearing structure in a simplified manner for convenience, but the same reference numerals as those in FIG. 1 denote the same or corresponding ones.

When assembling the spindle motor, FIG.
As shown in (a), insertion of the shaft 4 into the hanging portion 20 of the sleeve body 16 is started from the lower end portion 4a thereof, and as shown in (b) of the figure, an annular groove 4d for preventing lubricant outflow.
When it is inserted to the upper side, the lubricant 25 is arranged around the shaft 4 at the upper entrance of the hanging part 20.
The lubricant 25 is gradually drawn between the inner peripheral surface of the hanging portion 20 and the outer peripheral surface of the shaft 4 when the insertion of the lubricant is advanced.

As the insertion of the shaft 4 proceeds, the same figure (c)
As shown in FIG.
At the time of passing through the entrance of, the lubricant 25 taken in there is taken in and inserted into the hanging part 20. As a result, as shown in FIG. 3D, the lubricant 25 is applied to the intermediate groove portion 4c and the upper and lower radial dynamic pressure bearing portions sandwiching the intermediate groove portion 4c between the inner peripheral surface of the hanging portion 20 and the outer peripheral surface of the shaft 4. Spread enough. When the insertion of the shaft 4 is almost completed, a part of the lubricant 25 disposed at the entrance of the hanging part 20 that has not been injected into the intermediate groove part 4c and the upper and lower radial dynamic pressure bearing parts sandwiching the middle groove part 4c is left on the upper surface of the hanging part 20. It is injected between the lower thrust receiving surface and the thrust bearing surface 13 of the thrust plate 11.

The annular groove 4d on the lower end 4a side of the shaft 4 is inserted into the hanging portion 20 before the lubricant 25 is placed at the entrance of the hanging portion 20, and the inner surface of the groove is oil repellent. Since the treatment has been performed, the surface tension prevents the lubricant 25 from flowing out into the annular groove 4d when the shaft 4 is inserted. Therefore, it is possible to prevent the lubricant 25 from adhering to the lower end portion 4a side of the shaft 4.

[0018]

However, the above-mentioned assembling method has the following problems. That is, at the upper entrance of the hanging part 20, the shaft 4
A lubricant supply nozzle is used when the lubricant 25 is arranged around the nozzle, and its tip is, for example, as shown by an arrow in FIG.
The lubricant 25 is supplied toward the upper entrance of the hanging part 20, but the distribution of the supplied lubricant 25 may be biased toward the supply nozzle side as shown in FIG. 8B. .

Then, when the shaft 4 is inserted in such a state, the lubricant 25 is deviated and the lubricant 25 is drooped.
8 is drawn in between the inner peripheral surface of the shaft 0 and the outer peripheral surface of the shaft 4, but as shown in FIG. 8A, the lubricant 25 at the upper inlet of the drooping part 20 does not contact the lower thrust receiving surface of the drooping part 20. When straddling the lower surface of the thrust plate 11 and the thrust bearing surface 13, the lubricant 25 between the lower thrust receiving surface and the thrust bearing surface 13 rapidly abuts on the outer side due to the capillary phenomenon as the shaft 4 is inserted thereafter. Spread to.

In this case, the spreading speed of the lubricant 25 to the outside differs depending on the size of the distribution of the lubricant 25, and as shown by the alternate long and short dash line in FIG. The spread speed of the lubricant 25 is high, and the lubricant 25
The spreading speed of the lubricant 25 becomes slower in the portion where the amount is small. Therefore, the distribution of the lubricant 25 in the thrust plate 11 changes rapidly, and the lubricant 25 in the part where the spread speed of the lubricant 25 is fast wraps around the outside of the part in which the spread speed of the lubricant 25 is slow from both sides in the circumferential direction. Eventually, the generation of bubbles will occur.

When bubbles are mixed in the lubricant 25 in the dynamic pressure bearing portion, the pressure in this portion does not rise when the dynamic pressure is generated,
In the thrust dynamic pressure bearing part, pressure imbalance occurs in the circumferential direction, and smooth rotation support cannot be performed.
There is a problem that the lubricant 25 leaks out due to large expansion of bubbles when the temperature or the atmospheric pressure changes, especially when the temperature rises.

Here, in order to spread the lubricant 25 between the inner peripheral surface of the hanging part 20 and the outer peripheral surface of the shaft 4, after the lubricant 25 is injected into the upper inlet of the hanging part 20, or is injected. However, it is possible to rotate the hanging part 20 and the shaft 4 relatively.

However, since there is a gap between the hanging portion 20 and the shaft 4 for generating a dynamic pressure, as shown in FIG. When the shaft 4 is displaced with respect to the shaft 4, the injected lubricant 25 has a small gap between the hanging part 20 and the shaft 4 due to a capillary phenomenon as shown in FIG. It is drawn deep into the part.

Therefore, when the hanging portion 20 and the shaft 4 are rotated relative to each other in this state, the lubricant 25 deeply drawn in rotates in the rotational direction as shown by the alternate long and short dash line in FIG. To the underside of the shallow portion of the lubricant 14 via the void portion, resulting in generation of bubbles, and the same problem as described above occurs.

The present invention has been made in view of the above problems of the prior art, and its purpose is to introduce a lubricant such as oil into the dynamic pressure bearing portion to cause bubbles to be mixed therein. It is an object of the present invention to provide a method for assembling a dynamic pressure bearing, which can surely inject the fluid without increasing the reliability and productivity.

[0026]

In order to achieve the above object, in a method for assembling a dynamic pressure bearing according to the present invention, a shaft body and an inner peripheral portion of a substantially cylindrical surface shape on which the shaft body is fitted. And a sleeve body having a thrust receiving surface orthogonal to this, and in the dynamic pressure bearing in which the sleeve body can freely rotate relative to the shaft body via a lubricant, a part of the shaft body After inserting it into the inner circumference and disposing a lubricant around the shaft at the entrance of this inner circumference, insert the shaft into the inner circumference of the sleeve body, and the lubricant around the shaft will absorb the thrust receiving surface. When the shaft body is straddled, the insertion of the shaft body is stopped for a certain period of time, and the lubricant is evenly distributed around the shaft body.
It is characterized in that the insertion of the shaft body is restarted after the rest time.

In this case, the radial dynamic pressure bearing portion is formed by the outer peripheral surface of the shaft body and the inner peripheral surface of the inner peripheral portion of the sleeve body,
A thrust dynamic pressure bearing portion is formed by the thrust plate and the thrust receiving surface.Lubricant is mainly injected into the radial dynamic pressure bearing portion before the pause time in the shaft insertion process, and the thrust dynamic pressure bearing portion is mainly thrust after the pause time. It is preferable to inject a lubricant into the dynamic pressure bearing portion.

Further, an annular groove is provided coaxially outside the radial bearing corresponding position on the surface of the shaft body, and the lubricant is injected around the shaft body so that at least the shaft body uses the annular groove in the sleeve body. It is desirable to perform after the insertion to the position to be positioned in the inner peripheral portion of the above, and it is preferable to apply the oil repellent to the inner surface of this annular groove.

Further, after the insertion of the shaft body is completed, a lubricant may be supplied to the upper surface of the thrust plate, and the sleeve body may be equipped with a thrust holding plate forming another thrust dynamic pressure bearing portion between the thrust plate and the thrust plate. .

[0030]

[Operation] A part of the shaft is inserted into the inner peripheral part of the sleeve body, a lubricant is arranged around the shaft at the entrance of the inner peripheral part, and then the shaft body is inserted into the inner peripheral part of the sleeve body. Then, the lubricant is gradually drawn between the inner peripheral surface of the inner peripheral portion of the sleeve body and the outer peripheral surface of the shaft body. When the lubricant around the shaft straddles the thrust receiving surface and the thrust plate and the insertion of the shaft is stopped for a certain period of time, for example, the lubricant distributed to the lubricant supply nozzle side is biased around the shaft. Evenly distributed in. Then, when the insertion of the shaft body is restarted after the rest time, the lubricant around the shaft body is spread radially evenly between the thrust receiving surface and the thrust plate, and is supplied to the outer peripheral edge of the thrust plate.

Here, when the lubricant is injected around the shaft body, at least the annular groove formed on the outer side of the position corresponding to the radial bearing portion of the shaft body is inserted to the position where it is located inside the inner peripheral portion of the sleeve body. If this is done, the lubricant will not be drawn into the tip side of the annular groove of the shaft during the lubricant injection process. Especially, if the oil repellent is applied to the inner surface of the annular groove, it will move from the annular groove to the tip side. The leakage of the lubricant can be prevented more reliably.

[0032]

Embodiments of the present invention will be described with reference to FIGS. FIG. 1 shows a spindle motor for rotating a disk using this kind of dynamic pressure bearing, and its configuration has already been described, and will be omitted. Moreover, FIGS.
Shows the procedure for assembling the dynamic pressure bearing portion of the present spindle motor, focusing on the injection of the lubricant 25. The assembling method will be described below.

When assembling the dynamic pressure bearing portion, first, referring to FIG.
As shown in FIG. 5, the shaft 4 integrally provided with the thrust plate 11 is inserted into the inside of the hanging portion 20 of the sleeve body 16 of the rotor hub 15 from the lower end portion 4 a (press-fitting portion into the base member 1). This insertion is at least an annular groove 4d
Is performed up to a position located within the inner peripheral portion of the sleeve body 16. Actually, as shown in FIG. 3, the intermediate groove portion 4 c of the shaft 4 is inserted to a state in which the intermediate groove portion 4 c is located slightly above the upper surface of the hanging portion 20.

Next, the shaft 4 is inserted into the intermediate groove portion 4c.
4 is reached to a position slightly above the upper surface of the hanging part 20, the lubricant 25 is injected around the shaft 4 at the upper entrance of the hanging part 20 in this state, as shown in FIG. By this injection, a part of the lubricant 25 arranged around the shaft 4 enters between the inner peripheral surface of the hanging portion 20 and the outer peripheral surface of the shaft 4 due to a capillary phenomenon. Is. That is, the annular groove 4d drastically increases the gap between the inner peripheral surface of the hanging portion 20 and the outer peripheral surface of the shaft 4, and since the annular groove 4d is subjected to oil repellent treatment, the lubricant 25 has a surface tension. By this, it is possible to prevent it from spreading below that.

Thereafter, when the shaft 4 is further inserted, the lubricant 25 is gradually drawn between the inner peripheral surface of the hanging portion 20 and the outer peripheral surface of the shaft 4 as the shaft 4 descends.
In particular, when the intermediate groove portion 4c of the shaft 4 passes through the entrance of the drooping portion 20, a large amount of the lubricant 25 disposed therein is taken in and injected into the drooping portion 20. As a result, the lubricant 25 is sufficiently distributed between the inner peripheral surface of the hanging portion 20 and the outer peripheral surface of the shaft 4 to the intermediate groove portion 4c and the upper and lower radial dynamic pressure bearing portions that sandwich the intermediate groove portion 4c.

Then, as shown in FIG. 5, the shaft 4 is inserted to a position where the lubricant 25 around the shaft 4 straddles the thrust receiving surface of the hanging portion 20 and the thrust plate 11 at this point. The insertion of the shaft 4 is stopped for a fixed time. When the lubricant 25 straddles the thrust receiving surface of the hanging portion 20 and the thrust plate 11, the movement of the lubricant 25 in the circumferential direction of the shaft becomes relatively free, so that the insertion or movement of the shaft 4 is stopped and the lubricant 25 By promoting the movement of itself in the circumferential direction, the lubricant 25 is evenly distributed around the shaft 4.

When the insertion of the shaft 4 is restarted after a certain period of rest, the lubricant 25 is gradually drawn between the inner peripheral surface of the hanging portion 20 and the outer peripheral surface of the shaft 4 as the shaft 4 descends. The lubricant 25 spreads rapidly and evenly in the radial direction between the thrust receiving surface of the hanging portion 20 and the thrust bearing surface 13 of the thrust plate 11. Then, as shown in FIG. 6, when the insertion of the shaft 4 is almost completed, the entire radial bearing portion between the inner peripheral surface of the hanging portion 20 and the outer peripheral surface of the shaft 4, and the thrust receiving surface and the thrust of the hanging portion 20. The lubricant 25 is supplied to the entire lower thrust bearing portion between the plate 11 and the thrust bearing surface 13.

After completion of the above-mentioned assembly process, the lubricant 25 is injected into the upper thrust bearing portion. That is, FIG.
At, the lubricant is supplied onto the thrust bearing surface 12 of the thrust plate 11 so as to continue in a predetermined amount in the circumferential direction, and then the thrust cover 19 is fixed to the rotor hub 15. When the outer peripheral edge of the thrust cover 19 is attached to the upper surface of the inner peripheral portion of the sleeve body 16, the lower surface on the outer peripheral side of the thrust cover 19 is placed on the annular base portion 22 of the sleeve body 16, and the outer peripheral surface of the thrust cover 19 and the large diameter are larger. The upper inner peripheral surface of the peripheral wall 21 is brought into contact with and held.

At this time, the upper thrust receiving surface of the lower surface of the thrust cover 19 and the thrust bearing surface 1 of the thrust plate 11
The lubricant supplied to the thrust bearing surface 12 spreads in the inner and outer circumferential directions between the upper thrust receiving surface of the thrust cover 19 and the thrust bearing surface 12 of the thrust plate 11. Are filled in to form the upper thrust bearing portion. Then, in this state, the upper wall of the large-diameter peripheral wall 21 is caulked to the shaft side by plastic deformation processing,
The thrust cover 19 is tightly fixed to the sleeve body 16.

In the assembly process described above, the insertion of the shaft 4 into the sleeve body 16 is actually performed by the hanging portion 20.
The lower end surface of the shaft 4 is supported by a jig that is passed from the inside, and this jig is gradually lowered. The shaft 4 is lowered by its own weight, and the insertion operation is performed. If this method is adopted, the surface of the shaft 4 or the hanging portion 2
If foreign matter such as dust or dirt adheres to the inner surface of 0, etc., even if the jig is lowered, the foreign matter is caught in the slight gap between the shaft 4 and the hanging portion 20 and the shaft 4 does not descend. Therefore, it is possible to detect the presence / absence of foreign matter by detecting the presence / absence of the lowering of the shaft 4 accompanying the lowering of the jig.

Although the embodiment of the method for assembling the dynamic pressure bearing of the present invention has been described above, the design can be freely changed or modified without departing from the spirit of the present invention. That is, the various partial structures shown in the present embodiment can be used in combination, and the form and quantity of the dynamic pressure groove of the dynamic pressure bearing can be freely selected.

[0042]

Since the method of assembling the dynamic pressure bearing of the present invention has the above-mentioned structure, it has the following effects.

A part of the shaft body is inserted into the inner peripheral part of the sleeve body, a lubricant is arranged around the shaft body at the entrance of the inner peripheral part, and the shaft body is inserted into the inner peripheral part of the sleeve body. When the lubricant is drawn between the inner peripheral surface of the inner peripheral portion of the sleeve body and the outer peripheral surface of the shaft body, when the lubricant around the shaft body straddles the thrust receiving surface and the thrust plate, Since the insertion is paused for a certain period of time, the lubricant can be evenly distributed around the shaft body even if the lubricant is distributed to the lubricant supply nozzle side, for example. The lubricant around the shaft can be spread evenly radially between the thrust receiving surface and the thrust plate when the insertion of the is resumed, and the lubricant can be injected without causing the inclusion of air bubbles. .

Further, when the lubricant is injected around the shaft body, at least the annular groove formed on the outer side of the position corresponding to the radial bearing portion of the shaft body is inserted to a position to be positioned inside the inner peripheral portion of the sleeve body. By doing so, the lubricant will not be drawn into the tip side of the annular groove of the shaft during the lubricant injecting process. Especially, if the oil repellent is applied to the inner surface of the annular groove, it will move from the annular groove to the tip side. The leakage of the lubricant can be prevented more reliably.

[Brief description of drawings]

FIG. 1 is a sectional view showing an entire spindle motor to which the present invention is applied.

FIG. 2 is an enlarged cross-sectional view of a main part immediately before the shaft is inserted, showing an embodiment of the method for assembling the dynamic pressure bearing according to the present invention.

FIG. 3 is an enlarged sectional view of an essential part showing the shaft insertion process in the embodiment.

FIG. 4 is an enlarged cross-sectional view of a main part when a lubricant is injected in the example.

FIG. 5 is an enlarged cross-sectional view of a main part showing a time of temporarily holding the shaft insertion in the example.

FIG. 6 is an enlarged cross-sectional view of an essential part showing the state when the shaft has been inserted in the embodiment.

7A and 7B are partially enlarged cross-sectional views showing a conventional method for assembling a dynamic pressure bearing, in which FIG. 7A is immediately before shaft insertion, FIG. 7B is lubricant injection, and FIG. Injection process, (d) is when the shaft insertion is completed.

8A and 8B are views for explaining the bubble mixing phenomenon in FIG. 7, where FIG. 8A is a partially enlarged sectional view, and FIG. 8B is a sectional plan view of FIG.

9A and 9B are views for explaining a bubble mixing phenomenon by another conventional assembling method, in which FIG. 9A is a cut plan view and FIG. 9B is a cut front view.

[Explanation of symbols]

 4 shaft 11 thrust plate 12, 13 thrust bearing surface 16 sleeve body 19 thrust cover 20 hanging part 25 lubricant

Claims (5)

[Claims] 1. A shaft body, and a sleeve body having a substantially cylindrical inner peripheral portion on which the shaft body is fitted and a thrust receiving surface orthogonal to the inner peripheral portion, and the shaft body. A method of assembling a dynamic pressure bearing, wherein the sleeve body is capable of freely rotating relative to each other via a lubricant, wherein a part of the shaft body is inserted into an inner peripheral portion of the sleeve body, and an inlet of the inner peripheral portion is provided. In after disposing a lubricant around the shaft body, the shaft body is inserted into the inner peripheral portion, and when the lubricant around the shaft body straddles the thrust receiving surface and the thrust plate, A method for assembling a dynamic pressure bearing, characterized in that the insertion of the shaft is suspended for a certain period of time so that the lubricant is evenly distributed around the shaft, and the insertion of the shaft is restarted after the suspension. 2. A radial dynamic pressure bearing portion is formed by the outer peripheral surface of the shaft body and an inner peripheral surface of the inner peripheral portion, and a thrust dynamic pressure bearing portion is formed by the thrust plate and the thrust receiving surface. A lubricant is mainly injected into the radial dynamic pressure bearing portion before the pause time in the insertion process of the shaft body, and a lubricant is mainly injected into the thrust dynamic pressure bearing portion after the pause time. Item 1. A method for assembling a dynamic pressure bearing according to item 1. 3. An annular groove is provided coaxially outside the radial bearing portion corresponding position on the surface of the shaft body, and the lubricant is injected around the shaft body at least in the shaft body. The method for assembling a dynamic pressure bearing according to claim 1, which is performed after the annular groove is inserted to a position where the annular groove is located inside the inner peripheral portion. 4. The method of assembling a dynamic pressure bearing according to claim 3, wherein an oil repellent is applied to the inner surface of the annular groove. 5. A thrust retainer plate, which is provided with a lubricant on the upper surface of the thrust plate after completion of insertion of the shaft body and forms another thrust dynamic pressure bearing portion between the sleeve body and the thrust plate. The method for assembling a dynamic pressure bearing according to claim 1, wherein the bearing is mounted.