JPH08326749A - Fluid bearing device, and its manufacture - Google Patents

Abstract

PURPOSE: To provide a fluid bearing device and its manufacture where static pressure pockets and dynamic pressure generation sources can be formed easily with short processing time, and the formation of a bearing with a small diameter is possible, and further bearings different in length can be manufactured easily. CONSTITUTION: Circular firsts steel plates 44 and circular second steel plates 50, where recesses 48a-48d are partitioned off, are made a plural number of sheets each. The second steel plates 50 are stacked a specified number of sheets, and these stacked second steal plates 50 are caught with a specified number of sheets each of first steel plates 44 thereby being stacked. The recesses 48a-48d are stacked, being biased by a specified angle at a time in circumferential direction from each other, and the static pressure pockets 52a-52d being made by the recesses 48a-48d are partitioned off in the shape of being twisted in circumferential direction. The stacked first steel plates 44 and the second steel plates 50 are fixed together, thus a bearing is made, and the inside periphery of the bearing is polished and 6 rotary shaft is inserted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrodynamic bearing device for rotatably bearing a rotary shaft such as a main shaft of a machine tool through a pressure fluid and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, there are a hydrostatic bearing device and a hydrodynamic bearing device as a hydrodynamic bearing device that supports a rotary shaft by the pressure of a fluid. First, the case of a hydrostatic bearing device will be described.

As shown in FIG. 11, the hydrostatic bearing device 10 includes a cylindrical bearing 12 and a rotary shaft 14 inserted into the bearing 12. Rectangular static pressure pockets 16a to 16d are defined on the inner wall of the bearing 12, and lands 18a to 18d are formed between the static pressure pockets 16a to 16d (see FIG. 12). The static pressure pocket 16a
An edge portion that forms a boundary between 16d and the land portions 18a to 18d is formed parallel to the axial direction of the rotary shaft 14. Fluid supply passages 20a to 20d to which a pressure fluid is supplied are defined in substantially central portions of the static pressure pockets 16a to 16d, and the supply passages 20a to 20d communicate with a pressure fluid supply source (not shown).

In the above-mentioned structure, when a pressure fluid supply source (not shown) is energized, the pressure fluid has a constant pressure from the fluid supply passages 20a to 20d to the static pressure pocket 16a.
To 16d, the pressure of the fluid is applied to the outer circumference of the rotary shaft 14, and the rotary shaft 14 is levitationally supported by the fluid pressure.

A hydrostatic bearing device 1 according to such a conventional technique.
When manufacturing 0, the bearing 12 is first made of a material such as metal.
Is formed into a cylindrical shape, and the bearing 12 is attached to the index table 22 (see FIG. 13). Then, the milling machine 28 on which the end mill 26 is mounted is biased via the angle head 24, and the milling machine 28 and the index table 22 are operated to operate the bearing 12 and the end mill 26.
And the inner wall of the bearing 12 is cut to form the static pressure pockets 16a to 16d. In this case, milling machine 2
8 and the operation of the index table 22 are controlled by a program stored in a controller (not shown) connected to the milling machine 28 and the index table 22 in advance, and the bearing 12 and the end mill 26 are automatically moved.

Also, the angle head 24 and the end mill 2
In place of 6, a slot cutter (not shown) is used for the milling machine 2
There is also a manufacturing method in which the static pressure pockets 16a to 16d are attached to the machine No.

On the other hand, in the case of the dynamic pressure bearing device, the dynamic pressure generating groove is defined on either the bearing or the rotating shaft, but the spiral dynamic pressure generating groove should be defined on the inner wall of the bearing. Therefore, a spiral dynamic pressure generating groove is usually defined on the outer wall of the rotary shaft. That is, as shown in FIG. 14, a plurality of dynamic pressures are generated which are directed toward both sides in the axial direction from a predetermined position on the outer wall of the rotary shaft 32 of the dynamic pressure bearing device 30 and are inclined in the rotation direction (arrow A) of the rotary shaft 32. A groove 34 is defined. This rotating shaft 3
When 2 is inserted into the cylindrical bearing 36, the dynamic pressure generating groove 34 faces the inner wall of the cylindrical bearing 36.

In the above structure, when the rotary shaft 32 rotates, a fluid such as air is introduced from the outer end of the dynamic pressure generating groove 34 along the dynamic pressure generating groove 34 into the central portion of the bearing 36. , Substantially stays inside the dynamic pressure generating groove 34. The fluid pressure in the dynamic pressure generating groove 34 gradually increases, and this pressure causes the rotating shaft 32 to be supported in a floating manner.

The dynamic pressure generating groove 34 is defined by a cutting process using a milling machine or the like on the rotating shaft 32 formed in a cylindrical shape with a material such as metal.

[0010]

However, in the above-mentioned prior art, in the case of the hydrostatic bearing device 10, the index table 22 and the bearing 12 must be accurately centered, but this process cannot be automated. , Requires skill. Further, since the cutting process is performed inside the bearing 12, the cutting tool such as the end mill 26 is inevitably small, and if the cutting process is performed using the end mill 26 of this type, the processing time becomes long. Further, it is necessary to move the index table 22 and the milling machine 28 in a complicated manner, which requires a great number of man-hours for creating the control program. Further, in order to improve the performance such as the rotation accuracy of the hydrostatic bearing device 10, a hydrostatic pocket having a complicated shape may be required. When the hydrostatic pocket having the complicated shape is formed, the milling machine 28 is used. The operation of is more complicated, and it is extremely difficult to create a program, or the program cannot be created in some cases. Furthermore, when manufacturing the bearings 12 having different axial lengths, the bearings 12 to be manufactured
There is a problem that a program for controlling the operation of the index table 22 and the milling machine 28 must be created according to the length of, and the number of steps is increased.

Also in the case of the dynamic pressure bearing device 30, the index table and the milling machine must be moved intricately due to the shape of the dynamic pressure generating groove 34 as described above, and the number of steps for creating the control program is reduced. It will be extremely large. Furthermore, the dynamic pressure rigidity of the dynamic pressure bearing device 30,
In order to improve performance such as load capacity, a dynamic pressure generating groove with a more complicated shape may be required.However, with such a dynamic pressure generating groove, the movement of the milling machine becomes more complicated and programming is not possible. Various difficulties have been revealed, such as difficulty or making programming virtually impossible.

The present invention has been made in order to overcome the above-mentioned various inconveniences. The machining time is short, static pressure pockets and dynamic pressure generating grooves having complicated shapes can be easily formed, and the diameter can be increased. An object of the present invention is to provide a hydrodynamic bearing device capable of easily manufacturing a small bearing and a bearing having a different length, and a manufacturing method thereof.

[0013]

To achieve the above object, the present invention comprises a bearing for inserting a rotary shaft and a static pressure pocket defined on an inner wall of the bearing. In the hydrodynamic bearing device that rotatably supports the rotary shaft by the pressure of the fluid supplied to the plurality of annular first
And a ring-shaped second plate member that is sandwiched by the plurality of first plate members and that is laminated with the plurality of first plate members and has a recess on the inner peripheral surface thereof. It is characterized in that the respective recesses are defined as static pressure pockets by communicating with each other.

Further, the present invention is a method for manufacturing a hydrodynamic bearing device, which is constructed by laminating plate members formed in a predetermined shape and has static pressure pockets defined on the inner wall thereof. A first step of preparing a plurality of sheets, a second step of preparing a plurality of annular second plate materials having recesses on the inner peripheral surface, and a second plate material laminated by a plurality of the first plate materials By sandwiching the recesses, the respective recesses communicate with each other to define a static pressure pocket, and a fourth step of pressing and fixing the stacked first plate member and second plate member in the axial direction. And a process.

Further, according to the present invention, a bearing for inserting the rotary shaft and a dynamic pressure generating groove defined on an inner wall of the bearing are provided, and the rotary shaft rotates to introduce a fluid into the dynamic pressure generating groove. In the hydrodynamic bearing device that rotatably supports the rotary shaft by the fluid pressure generated by the above, a plurality of annular first plate members and the plurality of first plate members are sandwiched and a plurality of them are stacked. And an annular second plate member having a recess on the inner peripheral surface thereof, and the recesses of the plurality of second plate members stacked together are defined as a dynamic pressure generating groove by communicating with each other. And

Furthermore, the present invention is a method for manufacturing a hydrodynamic bearing device, which is constructed by stacking plate members formed in a predetermined shape, and has a dynamic pressure generating groove defined on the inner wall thereof, which is the first annular shape. A first step of preparing a plurality of plate materials, a second step of preparing a plurality of annular second plate materials having recesses on the inner peripheral surface, and a plurality of stacked second plate materials by the plurality of second plate materials A third step of sandwiching one plate member so that the respective recesses communicate with each other to define a dynamic pressure generation groove, and the stacked first plate member and second plate member are pressed and fixed in the axial direction. And a fourth step.

[0017]

According to the present invention, in the case of the hydrostatic bearing device, the pressure fluid is introduced into the hydrostatic pocket defined by the laminated second plate members. The rotating shaft is evenly supported by the pressure fluid. This bearing is formed by laminating and fixing a first plate material and a second plate material, and a static pressure pocket is defined by a recess of a plurality of second plate materials that are laminated. Therefore, complicated processing by a milling machine, which has been conventionally required, becomes unnecessary. In addition, since the recesses are offset in the circumferential direction and stacked, a static pressure pocket having a complicated shape can be defined by a simple process.

In the case of the dynamic pressure bearing device, the fluid is introduced from the end side of the mountain-shaped dynamic pressure generating groove defined by the laminated second plate member, and the fluid is substantially introduced into the dynamic pressure generating groove. Stay As a result, the fluid pressure in the dynamic pressure generation groove gradually increases, and the rotating shaft is levitationally supported by this pressure fluid. In this bearing, since the second plate member is stacked by eccentrically arranging the second plate member in the circumferential direction so that the recess of the second plate member becomes a mountain shape with respect to the rotation direction of the rotating shaft, the dynamic pressure generated along the axial direction is generated. The groove can be easily defined on the inner wall side of the bearing.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A hydrodynamic bearing device according to the present invention will be described in detail below with reference to the accompanying drawings, with reference to preferred embodiments in relation to its manufacturing method.

First, a hydrostatic bearing device will be described as a first embodiment. 1 is a partial cross-sectional perspective view of a hydrostatic bearing device according to a first embodiment of the present invention, and FIG. 2 is a plan view of a steel plate as a first plate material constituting the hydrostatic bearing device shown in FIG. 3 is a plan view of a steel plate as a second plate material that constitutes the hydrostatic bearing device shown in FIG. 1, FIG. 4 is a perspective view showing the configuration of the hydrostatic bearing device shown in FIG. 1, and FIG. FIG. 6 is a sectional view of the hydrostatic bearing device shown in FIG. 1, and FIG. 6 is a development view of the hydrostatic bearing device shown in FIG.

In FIG. 1, reference numeral 40 indicates a hydrostatic bearing device according to the first embodiment. This hydrostatic bearing device 40
In manufacturing the first, first, a circular hole 42 is defined by press working, wire cutting, laser cutting, or the like.
A predetermined number of steel plates 44 are formed (see FIG. 2). On the other hand, the hole 46 having the same diameter as that of the first steel plate 44 is defined, and the recesses 48a to 48d are defined around the hole 46.
A predetermined number of steel plates 50 are formed (see FIG. 3).

A predetermined number of the second steel plates 50 are laminated, and a predetermined number of the second steel plates 50 are laminated.
It is sandwiched by and laminated (see FIG. 4). Accordingly, the recesses 48a to 48d communicate with each other so that the static pressure pocket 52 is formed.
a to 52d, each static pressure pocket 52a.
The first edge portions 54a to 54d in the circumferential direction and the second edge portions 56a to 56d on the other side are formed in the to 52d (see FIG. 5). At this time, each recess 48 of the second steel plate 50 is
a to 48d are stacked so as to be offset from each other by a predetermined angle in the circumferential direction, and one first corner portion 58a to 58d of the first edge portions 54a to 54d and the other second corner portion 60a to 60d.
It is displaced in the circumferential direction by a length B with respect to d, and similarly, the third corner corner portions 62a to 62d of the second edge portions 56a to 56d are different from the other fourth corner corner portions 64a to 64d. The static pressure pockets 52a to 52d are formed in a twisted shape along the circumferential direction (see FIG. 6).

The interval between the first corner portion 58a and the third corner portion 62b adjacent to the first corner portion 58a is formed to be narrower than the length B. Similarly, the first corner portion 58a is formed. 58b and third
Corner portion 62c, first corner portion 58c and third corner portion 62d,
The distance between the first corner portion 58d and the third corner portion 62a is smaller than the length B. Therefore, the first edge portions 54a-5
The vicinity of the first corner portions 58a to 58d of 4d is the second edge portion 56.
The vicinity of the fourth corner portions 64b to 64a of b to 56a overlaps the length C in the axial direction.

The first steel plate 44 and the second steel plate 44 thus laminated
The steel plate 50 is pressed in the thickness direction thereof, and is bolted or fixed by adhesion to form the bearing 66. As the method of fixing by adhesion, the laminated first steel plate 44 and the second steel plate 50 are vacuum impregnated with synthetic resin, or the first steel plate 44 and the second steel plate 50 are heated to be vacuum impregnated with the low temperature molten metal. There is also a method of
An adhesive may be applied to the steel plate 44 and the second steel plate 50, and after stacking, pressure may be applied to fix them.

Fluid supply passages 68a to 68d into which a pressure fluid is introduced are defined at substantially central portions of the static pressure pockets 52a to 52d thus constructed. The fluid supply passages 68a to 68d are defined by using a drill or the like from the outer wall of the bearing 66. The fluid supply passages 68a to 68
d is connected to a pressure fluid supply source (not shown).

Next, the inner circumference of the bearing 66 is polished to make the first
Burrs of the steel plate 44 and the second steel plate 50, adhesives, etc. are scraped off. Then, the rotary shaft 70 is inserted into the bearing 66.

Next, the operation of the hydrostatic bearing device 40 according to this embodiment will be described.

When a pressure fluid supply source (not shown) is energized, a fluid such as oil is introduced from the fluid supply passages 68a to 68d into the static pressure pockets 52a to 52d at a constant pressure, and the fluid is provided on the outer periphery of the rotary shaft 70. Pressure is applied to the rotary shaft 7
Zero is levitated and supported by this fluid pressure. Therefore, the rotary shaft 70 can rotate inside the bearing 66 with extremely small friction.

When the rotating shaft 70 has irregularities or circularity distortion along its axial direction, for example, if a minute convex portion 72 extends in the axial direction of the rotating shaft 70, the convex portion 72 will be formed. When facing the static pressure pocket 52a, the rotary shaft 70 tends to be displaced in the direction opposite to the convex portion 72 due to the fluid pressure applied to the convex portion 72 (see FIG. 5). In this case, the rotary shaft 7
When 0 rotates, the protrusion 72 engages with the second corner portion 60a of the static pressure pocket 52a (see FIG. 6), and when further rotated, the protrusion 72 relatively moves the first edge 54a,
The area of the convex portion 72 facing the static pressure pocket 52a gradually decreases. Therefore, the fluid pressure applied to the convex portion 72 is gradually reduced, and the rotary shaft 70 is displaced toward the center of its axis.

The convex portion 72 has the first corner portion 58a.
Immediately before reaching the second edge 56b adjacent to the second edge 56b.
Of the static pressure pocket 52a and the static pressure pocket 52b is applied to the convex portion 72.

When the rotary shaft 70 further rotates, the area of the convex portion 72 facing the static pressure pocket 52b increases, the fluid pressure applied to the convex portion 72 gradually increases, and the rotary shaft 70 again has the convex portion 72. And deviate in the opposite direction. Then, the convex portion 72 reaches the position facing the static pressure pocket 52b through the third corner portion 62b.

As described above, the pressure applied to the convex portion 72 is the first
Since the edge portions 54a to 54d and the second edge portions 56a to 56d are gradually changed, the deviation from the axis of the rotating shaft 70 does not suddenly occur, and the rotating shaft 70 rotates without center runout. Also,
The convex portion 72 always has one of the static pressure pockets 52a to 52d.
Since the fluid pressure is applied from the above, the deviation amount of the rotating shaft 70 is suppressed, and the rotation accuracy is improved.

Hydrostatic bearing device 40 having different axial lengths
In the case of manufacturing, the hydrostatic bearing device 40 having a desired length can be obtained by the same manufacturing method only by changing the number of laminated first steel plates 44 and second steel plates 50.

Next, a dynamic pressure bearing device will be described as a second embodiment.

FIG. 7 is a partial cross-sectional perspective view of a hydrodynamic bearing device according to a second embodiment of the present invention, and FIG. 8 is a steel plate as a third plate material constituting the hydrodynamic bearing device shown in FIG. FIG. 9 is a plan view of a steel plate as a fourth plate material forming the dynamic pressure bearing device shown in FIG. 7, and FIG. 10 is a perspective view showing the structure of the dynamic pressure bearing device shown in FIG. 7. .

In FIG. 7, reference numeral 80 indicates a hydrodynamic bearing device according to the second embodiment. This dynamic pressure bearing device 80
In manufacturing the same, first, similarly to the first embodiment, a third steel plate 84 in which a circular hole 82 is defined, and the third steel plate 8 are formed.
A hole 86 having the same diameter as that of No. 4 is defined, and a predetermined number of fourth steel plates 90 having a plurality of recesses 88 defined around the hole 86 are formed (see FIGS. 8 and 9).

Next, a predetermined number of the third steel plates 84 are laminated, and a predetermined number of the fourth steel plates 84 are laminated.
It is sandwiched by steel plates 90 and laminated (see FIG. 10). At this time, the recesses 88 of the fourth steel plate 90 are stacked so as to be offset from each other by a predetermined angle in the circumferential direction, so that the recesses 88 communicate with each other and are defined as the dynamic pressure generating grooves 92. . Further, the dynamic pressure generation groove 9 formed of the fourth steel plate 90 stacked on one end side of the stacked third steel plate 84.
2 and the dynamic pressure generating groove 92 formed of the fourth steel plate 90 laminated on the other end side are arranged so that the deviation directions thereof are opposite to each other so as to be inclined in the opposite directions along the axis. Stack. As a result, the recess 88 of the fourth steel plate 90 stacked on one end side and the recess 8 of the fourth steel plate 90 stacked on the other end side.
8, the dynamic pressure generating groove 92 is defined in a chevron shape. In this case, since the third steel plate 84 is sandwiched by the fourth steel plates 90 on one end side and the other end side, the recesses 88 on the one end side and the other end side are blocked by the third steel plate 84, respectively. Become.

The third steel plate 84 and the fourth steel plate laminated in this way
The bearing 94 is formed by pressing the steel plate 90 in its thickness direction and fastening it by bolting or adhering.

Next, the inner circumference of the bearing 94 is polished to make a third
Burrs of the steel plate 84 and the fourth steel plate 90, adhesives, etc. are scraped off. Then, the rotary shaft 96 is inserted into the bearing 94.

Next, the operation of the dynamic pressure bearing device 80 according to this embodiment will be described.

When the rotary shaft 96 rotates in the direction of arrow D,
A fluid such as air around the rotary shaft 96 is introduced from the opening 98 of the dynamic pressure generating groove 92 by friction with the rotary shaft 96 (see FIG. 7). This fluid moves along the dynamic pressure generating groove 92 to reach the end portion 100 of the dynamic pressure generating groove 92, and the fluid is supplied from the dynamic pressure generating groove 92, so that the fluid becomes high pressure at the end portion 100. The rotating shaft 96 is levitationally supported by this pressure, and the rotating shaft 96 can rotate inside the bearing 94 with extremely small friction.

Dynamic bearing device 80 having different axial lengths
In the case of manufacturing, the hydrodynamic bearing device 80 having a desired length can be obtained by the same manufacturing method only by changing the number of stacked third steel plates 84 and fourth steel plates 90.

[0043]

According to the hydrodynamic bearing device and the manufacturing method thereof according to the present invention, the following effects and advantages can be obtained.

The bearing is formed by laminating and fixing the first steel plate and the second steel plate, and the static pressure pocket and the dynamic pressure generating groove are defined by the recess of the second steel plate. For this reason, complicated machining with a cutting tool such as a milling machine is not required, and the machining time can be shortened and the manufacturing cost can be reduced. Further, since the recesses are eccentrically stacked to be stacked, static pressure pockets and dynamic pressure generating grooves having a complicated shape can be defined by a simple process, and improvement in performance such as rotation accuracy is achieved. . Further, a bearing having a small diameter can be easily manufactured, and it becomes possible to manufacture a bearing having a different axial length by simply changing the number of laminated first steel plates and second steel plates.

[Brief description of drawings]

FIG. 1 is a partial sectional perspective view of a hydrostatic bearing device according to a first embodiment of the present invention.

2 is a plan view of a first steel plate forming the hydrostatic bearing device shown in FIG. 1. FIG.

FIG. 3 is a plan view of a second steel plate forming the hydrostatic bearing device shown in FIG.

4 is a perspective view showing the configuration of the hydrostatic bearing device shown in FIG. 1. FIG.

5 is a cross-sectional view of the hydrostatic bearing device shown in FIG.

6 is a development view of the hydrostatic bearing device shown in FIG. 1. FIG.

FIG. 7 is a partial cross-sectional perspective view of a dynamic pressure bearing device according to a second embodiment of the present invention.

8 is a plan view of a third steel plate forming the dynamic pressure bearing device shown in FIG. 7. FIG.

9 is a plan view of a fourth steel plate forming the dynamic pressure bearing device shown in FIG. 7. FIG.

10 is a perspective view showing the structure of the dynamic pressure bearing device shown in FIG. 7. FIG.

FIG. 11 is a partial cross-sectional perspective view of a hydrostatic bearing device according to a conventional technique.

12 is a sectional view of the hydrostatic bearing device shown in FIG.

13 is a front view of an apparatus for manufacturing the hydrostatic bearing device shown in FIG.

FIG. 14 is a partial cross-sectional perspective view of a dynamic pressure bearing device according to a conventional technique.

[Explanation of symbols]

40 ... Hydrostatic bearing device 44, 50, 8
4, 90 ... Steel plates 48a to 48d, 88 ... Recesses 52a to 52d ...
Hydrostatic pockets 66, 94 ... Bearings 70, 96 ... Rotating shaft 80 ... Dynamic pressure bearing device 92 ... Dynamic pressure generating groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuneo Takiguchi 1-10-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd.

Claims (10)

[Claims] 1. A bearing having a rotary shaft inserted therethrough, and a static pressure pocket defined on an inner wall of the bearing. The rotary shaft is rotatably supported by the pressure of a fluid supplied to the static pressure pocket. In the hydrodynamic bearing device, a plurality of annular first plate members, and an annular second plate member that is sandwiched by the plurality of first plate members, is stacked, and has a recess on the inner peripheral surface, A hydrodynamic bearing device comprising: a plurality of second plate members, wherein the recesses of the laminated second plate members communicate with each other so as to be defined as static pressure pockets. 2. The hydrodynamic bearing device according to claim 1, wherein the recesses of each of the plurality of laminated second plate members are circumferentially offset from each other and laminated, and the hydrostatic pocket has an axial line of the second plate member. A hydrodynamic bearing device, wherein the hydrodynamic bearing device is defined by being twisted along a direction. 3. A hydrodynamic bearing device according to claim 2, wherein the start end of one static pressure pocket overlaps with the end of another static pressure pocket which is adjacent to each other in the circumferential direction in the axial direction of the second plate member. A hydrodynamic bearing device characterized by the above. 4. A method for manufacturing a hydrodynamic bearing device, which is constructed by stacking plate members formed in a predetermined shape and has static pressure pockets defined on the inner wall thereof, and a plurality of annular first plate members are prepared. A first step; a second step of preparing a plurality of annular second plate members having recesses on the inner peripheral surface; and a sandwiching of a plurality of second plate members laminated by the plurality of first plate members. A third step in which the respective recesses communicate with each other to define a static pressure pocket, and the stacked first plate member and second plate member are pressed in the axial direction,
A fourth step of fixing, and a method of manufacturing a hydrodynamic bearing device, comprising: 5. The method for manufacturing a hydrodynamic bearing device according to claim 4, wherein in the third step, the recesses of the plurality of second plate materials are circumferentially offset from each other and stacked. A method of manufacturing a hydrodynamic bearing device, wherein the recess is defined as a static pressure pocket twisted along the axial direction of the second plate member. 6. A bearing which passes through a rotary shaft, and a dynamic pressure generating groove defined on an inner wall of the bearing, wherein the rotary shaft rotates to introduce a fluid into the dynamic pressure generating groove. In a hydrodynamic bearing device that rotatably supports the rotary shaft by a fluid pressure, a plurality of annular first plate members and a plurality of the first plate members are sandwiched, and a plurality of the first plate members are laminated and an inner peripheral surface is formed. And a second annular plate member having a recess, and the recesses of the plurality of laminated second plate members communicate with each other to define a dynamic pressure generating groove. apparatus. 7. The hydrodynamic bearing device according to claim 6, wherein the dynamic pressure generating groove defined by the plurality of laminated second plate members is formed in a mountain shape in the rotation direction of the rotary shaft. A hydrodynamic bearing device characterized by the above. 8. The hydrodynamic bearing device according to claim 7, wherein the dynamic pressure generating groove is blocked by disposing the first plate member on the mountain-shaped top of the dynamic pressure generating groove. Hydrodynamic bearing device. 9. A method of manufacturing a hydrodynamic bearing device, comprising a plurality of plate members formed in a predetermined shape laminated together, wherein a dynamic pressure generating groove is defined on an inner wall, wherein a plurality of annular first plate members are prepared. And a second step of preparing a plurality of annular second plate members having recesses on the inner peripheral surface thereof, and sandwiching a plurality of first plate members stacked by the plurality of second plate members. Thus, a third step in which the respective recesses communicate with each other to define a dynamic pressure generation groove, and the stacked first plate member and second plate member are pressed in the axial direction,
A fourth step of fixing, and a method of manufacturing a hydrodynamic bearing device, comprising: 10. The method for manufacturing a hydrodynamic bearing device according to claim 9, wherein in the third step, each recess of the plurality of second plate members is formed in a mountain shape in the rotation direction of the rotation shaft. A method of manufacturing a hydrodynamic bearing device, comprising stacking the second plate members so as to be offset from each other in the circumferential direction so as to form a dynamic pressure generating groove.