JPH10331841A - Dynamic pressure fluid bearing device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radial dynamic pressure bearing and a thrust dynamic pressure bearing easily at a low cost, and without requiring a complicated management. SOLUTION: A radial bearing 20 is composed of a shaft; and a bearing member 14 having a bearing hole 8 in order to arrange the shaft rotatable; a dynamic pressure groove 30 for generating the radial dynamic pressure is provided at least either one side of the peripheral surface of the shaft or the inner peripheral surface of the bearing hole, and the peripheral surface of the shaft or the inner peripheral surface of the bearing hole where the dynamic pressure groove 30 is provided is made of a metal for die-cast. The cross section form of the dynamic pressure groove 30 is within the scope surrounded by an isosceles triangle with the base of the groove width, and the height of the groove depth of 1 μm to 15 μm and an isosceles trapezoid with the base of the groove width, the height of the groove depth of 1 μm to 15 μm, and the angle made by the base and the hypotenuse is 30 deg., and the peripheral surface of the shaft providing the dynamic pressure groove, or the inner peripheral surface of the bearing hole is formed on a die-cast formation.

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 set for an apparatus having a rotating portion such as a motor, and a method of manufacturing the hydrodynamic bearing device.

[0002]

2. Description of the Related Art As an apparatus requiring a bearing, for example, a motor is used as an example. The motor is used for holding a disk-type information recording medium such as a hard disk or an optical disk for continuous rotation. In this type of motor, if the rotating shaft does not always rotate accurately with respect to the bearing, eccentricity occurs in the rotating information recording medium, and a signal is recorded on the information recording medium or the information recording medium is recorded. It becomes difficult to read the signal recorded in the memory. From such a viewpoint, it is necessary to set a dynamic pressure bearing in this type of motor and to rotate the motor with reduced friction between the shaft and the bearing. As described above, a dynamic pressure bearing is sometimes used for the purpose of rotating with reduced friction. The dynamic pressure bearing includes a radial dynamic pressure bearing and a thrust dynamic pressure bearing.

[0003]

However, as an example of forming a groove of a conventional radial dynamic pressure bearing, Japanese Patent Application Laid-open No.
Although it is disclosed in US Pat. No. 67129 or the like, there are problems that manufacturing equipment is expensive, processing time is long, complicated processing steps and secondary processing are required, and mass production of a radial dynamic pressure bearing at a low cost in a short time. There is a problem to do. When manufacturing grooves for radial dynamic pressure bearings, the shape accuracy of the grooves obtained by machining cannot be obtained to a sufficiently satisfactory degree.If the bearing is made of resin, the strength of the bearing is weak, and wear and deformation will occur. It becomes a problem. An example of manufacturing a groove of a thrust dynamic pressure bearing is disclosed in Japanese Patent Application Laid-Open No. 8-275446. However, any of the conventional methods has the same problem as the groove of the radial dynamic pressure bearing. A satisfactory groove cannot be obtained. Therefore, the present invention solves the above-mentioned problems, and provides a hydrodynamic bearing in which a hydrodynamic bearing device such as a radial hydrodynamic bearing or a thrust hydrodynamic bearing can be obtained reliably and easily at low cost and without requiring complicated management. It is an object of the present invention to provide a device and a method for manufacturing a hydrodynamic bearing device.

[0004]

According to the present invention, a radial bearing is constituted by a shaft and a bearing member having a bearing hole for rotatably arranging the shaft.
At least one of the peripheral surface of the shaft and the inner peripheral surface of the bearing hole is provided with a dynamic pressure groove for generating a radial dynamic pressure, and the peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is a metal for die casting. The cross-sectional shape of the dynamic pressure groove is based on the groove width,
An isosceles triangle having a groove depth of 1 μm to 15 μm as a height, and an isosceles trapezoid having a groove width as a base and an angle of 30 degrees between the base and the hypotenuse with a groove depth of 1 μm to 15 μm as a height The hydrodynamic bearing device is characterized in that the peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is formed by die casting.

In the present invention, since the cross-sectional shape of the dynamic pressure groove is set within a range surrounded by the above-mentioned isosceles triangle and isosceles trapezoid, the radial dynamic pressure groove can be reliably die-cast. If the groove depth is smaller than 1 μm, it is within the range of variation in the processing of the mold and variation in the molding of the mold, causing a problem that a molded product shape cannot be obtained properly, which is not practical. No groove depth 1
If it is larger than 5 μm or if the angle between the base and the oblique side exceeds 30 °, the molded product may be shaved by the undercut portion of the mold when the core pin is forcibly removed. As a result, the groove cross-sectional shape of the molded product is lost,
It is not preferable from the point that it is experimentally confirmed that the groove is not symmetrical within one groove cross-sectional shape and becomes a shape that is not preferable as the cross-sectional shape of the dynamic pressure groove.

The object of the present invention is to provide a thrust bearing comprising a first surface and a second surface opposed to each other, and a first surface and a second surface.
A dynamic pressure groove for generating thrust dynamic pressure is provided on at least one of the surfaces, and at least one of the first surface and the second surface provided with the dynamic pressure groove is made of a die casting metal, and a cross section of the dynamic pressure groove is provided. A range in which the shape is enclosed by an isosceles triangle having a groove width as a base and a groove depth of 1 μm to 30 μm in height, and a rectangle having a groove width as a base and a groove depth of 1 μm to 30 μm in height This is achieved by a hydrodynamic bearing device characterized in that at least one of the first surface and the second surface provided with the dynamic pressure groove is formed by die casting.

In the present invention, since the cross-sectional shape of the dynamic pressure groove is within a range surrounded by the isosceles triangle and the rectangle, the dynamic pressure groove of the thrust bearing can be reliably die-cast. If the groove depth is smaller than 1 μm, there is a problem that the processing variation of the mold and the variation in the molding of the mold fall within the range, and the shape of the molded product cannot be obtained properly.
It is not preferable in that it is not realistic, and if it exceeds 30 μm, it is not preferable because the molded product may be shaved by the undercut portion.

According to the present invention, a radial bearing is constituted by a shaft and a bearing member having a bearing hole for rotatably arranging the shaft. A dynamic pressure groove for generating radial dynamic pressure is provided on at least one of the inner peripheral surfaces, and the peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is made of metal for die casting, and the dynamic pressure The cross-sectional shape of the groove is such that the width of the groove is the base and the
It is surrounded by an isosceles triangle having a groove depth of 5 μm as a height and an isosceles trapezoid having a groove width as a base and an angle of 30 degrees between the base and an oblique side with a groove depth of 1 μm to 15 μm as a height. The peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is formed by die casting, and the opposed first surface and second surface constitute a thrust bearing. Second
At least one of the surfaces is provided with a dynamic pressure groove for generating thrust dynamic pressure, and this thrust bearing is arranged concentrically with the radial bearing, and at least one of the first surface and the second surface provided with the dynamic pressure groove is provided. It is made of die-casting metal, and the cross-sectional shape of the dynamic pressure groove is an isosceles triangle having a groove width as a base and a groove depth of 1 μm to 30 μm as a height, a groove width as a base and a groove width of 1 μm to 30 μm Wherein at least one of the first surface and the second surface provided with the dynamic pressure grooves is formed by die-casting. This is achieved by a bearing device. ADVANTAGE OF THE INVENTION In this invention, the dynamic pressure groove for radial bearings and the dynamic pressure groove for thrust bearings can be reliably die-cast.

The object of the present invention is to provide, in the present invention, a surface of a mold for forming a dynamic pressure groove for a radial bearing with respect to a shaft or a bearing hole for rotatably disposing the shaft. ,
An isosceles triangle having a groove width as a base and a height of 1 μm to 15 μm as a groove depth, and a groove width as a base and a groove width of 1 μm
A protrusion for forming a dynamic pressure groove is provided in which a groove depth of 15 to 15 μm is set as a height and an angle between the bottom side and the hypotenuse is within a range surrounded by an isosceles trapezoid of 30 degrees. The present invention is attained by a method of manufacturing a hydrodynamic bearing device, wherein an undercut portion on a mold is formed by forcibly removing a mold.

In the present invention, the surface of a mold member for forming a dynamic pressure groove for a shaft or a bearing hole for rotatably disposing the shaft is surrounded by the isosceles triangle and the isosceles trapezoid. Since the projections for forming the dynamic pressure grooves within the range to be provided are provided, the undercut portion on the die molding corresponding to the dynamic pressure grooves can be surely formed by forcibly removing the mold. If the groove depth is smaller than 1 μm, it is within the range of variation in the processing of the mold and variation in the molding of the mold, causing a problem that a molded product shape cannot be obtained properly, which is not practical. If the groove depth is larger than 15 μm or the angle between the bottom and the oblique side exceeds 30 °, the molded product may be cut off by the undercut of the mold when the core pin is forcibly removed. I do. As a result, it has been experimentally confirmed that the groove cross-sectional shape of the molded product is lost and is not symmetrical within one groove cross-sectional shape, resulting in an undesirable shape as the cross-sectional shape of the dynamic pressure groove. Not preferred.

In the present invention, the first and second surfaces opposing each other constitute a thrust bearing, and the first surface and the second surface are provided.
On the surface of a mold for forming a dynamic pressure groove for generating thrust dynamic pressure on at least one of the surfaces, the sectional shape of the dynamic pressure groove has a groove width as a base and a groove depth of 1 μm to 30 μm. An isosceles triangle with a height of
A method for manufacturing a hydrodynamic bearing device, comprising: forming a projection for molding within a range surrounded by a rectangle having a height of a groove depth of from 30 μm to 30 μm, and forming the hydrodynamic groove by a mold. Is achieved.

In the present invention, the dynamic pressure groove for the thrust bearing is
Molding can be reliably performed on at least one of the first surface and the second surface. If the groove depth is smaller than 1 μm, it is within the range of variation in the processing of the mold and variation in the molding of the mold, causing a problem that a molded product shape cannot be obtained properly, which is not practical. No groove depth 3
If it is larger than 0 μm, it is not preferable because the molded product is shaved by the undercut portion.

[0013]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIG. 1 shows a hydrodynamic bearing device 100 according to the present invention.
1 shows an example of a motor to which the preferred embodiment of the present invention is applied. This motor is a spindle motor,
For example, it is an electric motor for rotating a disk-shaped information recording medium such as a CD-ROM (read-only compact disk) disk and a mini disk (MD). This disk 6 can be detachably attached to the turntable 7.

The motor 10 is, roughly speaking, a rotor unit 1.
0a, the stator portion 10b and the hydrodynamic bearing device 100
have. The rotor portion 10a is also called a rotor, and includes a permanent magnet 2, a yoke 3, a boss 5, a shaft 4, a turntable 7,
have. The turntable 7 is a table for mechanically clamping the disc 6 in a detachable manner as described above, and is fixed to the boss 5 by press-fitting. The yoke 3 is made of a magnetic material, for example, a metal such as iron, and the yoke 3 is fixed to the boss 5 by press fitting or caulking. The permanent magnet 2 is fixed to the inner peripheral surface of the yoke 3. As the permanent magnet 2, for example, a plastic magnet or the like can be used. On the inner surface of the permanent magnet 2, N poles and S poles are alternately multi-polarized.

Next, the stator section 10b will be described. The stator section 10b is also called a stator, and has a substrate 13, a housing 14, a coil 12, an iron core 11, and the like.
The substrate 13 is provided with a wiring portion and the like for supplying electricity to the coil 12 from the outside. Coil 12 is iron core 1
For example, a plurality of coils 12 are arranged at equal intervals along a circumferential direction around the shaft 4. The coil 12 and the iron core 11 are fixed to the housing 14. Each coil 12 is arranged at an interval facing the permanent magnet 2.

The shaft 4 of the rotor section 10a is
b for the hydrodynamic bearing device 100
Are supported so as to be able to rotate continuously. The hydrodynamic bearing device 100 includes a radial bearing 20 and a thrust bearing 2.
Two. The radial bearing 20 is a part that receives the rotation of the shaft 4 in the radial direction RL, and the thrust bearing 22 is a part that receives the shaft 4 in the thrust direction ST.

In FIG. 1, when the disk 6 is mounted on the turntable 7 and the turntable 7 is rotated, the disk 6 is prevented from floating in the thrust direction ST, that is, the rotor portion 10a is moved in the thrust direction. In order to keep the position about ST constant,
Between the permanent magnet 2 and the iron core 11, the magnetic force (attraction force) of the permanent magnet 2 causes the end of the shaft 4 and the thrust bearing surface 9 to approach the rotor 10 a in the axial direction with respect to the stator 10 b. Thrust load is added. Housing 14 including bearing hole 8, thrust bearing surface 9 at the bottom of bearing hole 8
Is formed by die-casting using a metal for die-casting, for example, zinc die-casting, more specifically, ZDC-2 alloy.

FIG. 2 shows a state where the shaft 4 is removed from the housing 14 in FIG. A radial bearing 20 and a thrust bearing 22 are formed in the bearing hole 8 of the housing 14. As the radial bearing 20, the bearing hole 8
Along the inner peripheral surface 8a of the radial dynamic pressure generating groove 3
0 is formed. This dynamic pressure groove 30 is
In the example of FIG. 2, the dynamic pressure groove 30 for generating dynamic pressure is a Herring Bone (herring bone) type. Two sets are formed at predetermined intervals along the direction. 2, the dynamic pressure grooves 30 are shown in black, and the dynamic pressure grooves 30 are formed along the inner peripheral surface 8a of the bearing hole 8. On the other hand, as the thrust bearing 22, a dynamic pressure groove 40 is formed on the thrust bearing surface 9 as shown in FIG. This dynamic pressure groove 40
Is a spiral groove (spiral groove), for example.

The formation of the dynamic pressure groove 30 in the bearing hole 8 shown in FIG. 2 needs to be performed as follows. The core pin 200 shown in FIG. 4 is necessary for forming the dynamic pressure groove 30 for generating the radial dynamic pressure on the inner peripheral surface (also referred to as an inner diameter surface or a cylindrical surface) 8 a of the bearing hole 8. This core pin 2
Although the protrusions 210 and 220 are formed on 00, the protrusions 210 and 220 must be convex portions corresponding to the shapes of the dynamic pressure grooves 30 and 40 in FIG. By the way, in the embodiment of the present invention, this core pin is also used. However, in die casting, after the molten metal melt for die casting is cast into the cavity of the mold, the core pin is pulled out of the housing and the housing is taken out. In addition, the projection of the core pin is undercut in the direction in which the core pin is extracted. For this reason, when removing the core pin and removing the housing, the core pin must be forcibly removed (forcibly removed). At this time, the core pin may not come out of the product or even if it comes off, Since it is expected that the undercut portion cuts the inside of the housing and a dynamic pressure groove of a predetermined shape cannot be obtained, a radial dynamic pressure groove by die casting cannot be formed conventionally.

However, in the embodiment of the present invention, the present inventor has devised the shape of the dynamic pressure groove to be formed, and the above-mentioned undercut portion of the core pin at the time of die casting is formed inside the housing. This eliminates the problem that a dynamic pressure groove having a predetermined shape cannot be obtained by shaving. That is, as shown in FIG. 6, the cross-sectional shape of the dynamic pressure groove 30 of the radial bearing 20 shown in FIG.
Is an isosceles triangle having a height of a groove depth D of 1 μm to 15 μm and a groove depth D of 1 μm to 15 μm or less with a groove width W of 2 mm or less as a base as shown in FIG.
Is set within a range surrounded by an isosceles trapezoid having an angle θ formed by the base 50 and the hypotenuse 51 at 30 degrees, so that the core pin shown in FIGS. 4 and 5 is die-cast. By forcibly removing (forcibly removing) from the mold, molding was possible, and a dynamic pressure groove 30 having a predetermined shape was obtained.

FIG. 8A shows a dynamic pressure groove 30 within a range surrounded by the above-mentioned isosceles triangle and isosceles trapezoid.
Shows an example of the shape of a core pin 200 for forming
FIG. 8B shows an example of the shape of the dynamic pressure groove 30 of the bearing hole 8 formed by the core pin 200. The core pin 200 in FIG. 8A has a protrusion 210, and the dynamic pressure groove 30 in FIG. 8B is formed in the bearing hole 8 corresponding to the protrusion 210. In the cross-sectional shape of the dynamic pressure groove 30 in FIG. 8B, for example, the groove width W1 is 0.5 mm and the groove depth D1 is 7 μm, which is a substantially semicircular cross section. The width W10 of the protrusion 210 of the core pin 200 is also 0.5 m.
m, and the height D10 of the projection 210 is also 7 μm.

Core pin 2 as a mold shown in FIGS. 4 and 5
00 on the surface 205 as described above.
10 are formed. As described above, the cross-sectional shape of these projections 210 is equal to or almost equal to the cross-sectional shape of the dynamic pressure groove 30 to be formed. For example, a groove width of 2 mm or less is used as a base and a groove of 1 μm to 15 μm or less is used. An isosceles triangle with depth as height and, for example, 2 mm
With the following groove width as the base, the groove depth is 1 μm to 15 μm or less, and the height θ is within a range surrounded by an isosceles trapezoid having an angle θ of 30 degrees between the base and the hypotenuse. On the other hand, as shown in FIG. 5, another projection 220 is formed at the tip of the core pin 200. The projection 220 is a projection for forming the dynamic pressure groove 40 formed on the thrust bearing surface 9 shown in FIG.

The dynamic pressure groove 40 of the thrust bearing surface 9 shown in FIGS. 2 and 3 is, for example, a spiral groove, and the sectional shape of the dynamic pressure groove 40 is, for example, 1 μm with a groove width of 2 mm or less as a base.
An isosceles triangle whose height is a groove depth of not more than 30 μm and 1 μm to 3 μm whose bottom is a groove width of not more than 2 mm, for example.
It is formed so as to be within a range surrounded by a rectangle having a height of a groove depth of 0 μm or less. And the dynamic pressure groove 40 of the thrust bearing surface 9 is formed by die casting. In order to form the dynamic pressure groove 40 for the thrust bearing 22, the cross-sectional shape of the projection 220 of the core pin 200 shown in FIGS. 4 and 5 is, for example, 1 μm with a groove width of 2 mm or less as a base.
An isosceles triangle whose height is a groove depth of not more than 30 μm and 1 μm to 3 μm whose bottom is a groove width of not more than 2 mm, for example.
It is within a range surrounded by a rectangle having a height of the groove depth of 0 μm or less. Thrust bearing surface 9 having this dynamic pressure groove 40
Is formed by die casting using the core pin 200.

FIG. 9 shows an example of a motor provided with another embodiment of the hydrodynamic bearing device of the present invention. The motor 10 in FIG. 9 differs from the motor 10 in FIG. 1 in the structure of the hydrodynamic bearing device 300. The other parts of the motor 10 in FIG. 9 are the same as the motor 10 in FIG. Is omitted. This hydrodynamic bearing device 300 is the same as the motor 10 of FIG. 1 in having the radial bearing 20, but the hydrodynamic bearing device 300 has a thrust bearing 322 having a different structure. I have. This thrust bearing 3
22 is formed separately from the housing 14, and the thrust bearing 322 is fixed to the lower portion of the housing 14 by caulking. A thrust bearing surface 9 is formed on the upper surface of the thrust bearing 322, and a dynamic pressure groove 40 as shown in FIG. 3 similar to the thrust bearing surface 9 of the motor of FIG. Have been.

In the above-described embodiment, as shown in FIG. 2, a herringbone type dynamic pressure groove 3 for the radial bearing 20 is used.
Although 0 is formed, a spiral type radial bearing 420 may be provided on the inner peripheral surface 8a of the bearing surface 8 of the housing 14 as shown in FIG. The radial bearing 420 has a spiral dynamic pressure groove 430. Further, as shown in FIG. 11, the thrust bearing surface 9 on the inner bottom surface of the housing 14 may be provided with a herringbone type dynamic pressure groove 440 as shown in FIG.

The core pins 500 shown in FIGS. 12 and 13 correspond to the shapes of the dynamic pressure grooves 430 and 440 in FIGS.
, A spiral projection 510 and a herringbone projection 520 are formed. The motor housing 14 shown in FIGS. 1 and 9 and the thrust bearing 32 shown in FIG.
2 is made of a die-casting metal, and can be made by selecting from materials such as zinc die-cast, tin die-cast, aluminum die-cast, and magnesium die-cast.

Incidentally, the present invention also includes the following embodiments. As an embodiment of the present invention, a radial bearing is constituted by a shaft and a bearing member having a bearing hole for rotatably arranging the shaft, and either a peripheral surface of the shaft or an inner peripheral surface of the bearing hole is formed. In at least one of them, a dynamic pressure groove for generating radial dynamic pressure is provided, and the peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is made of die casting metal, and the sectional shape of the dynamic pressure groove is , With the groove width at the bottom and 1 μm to 1 μm
It is surrounded by an isosceles triangle having a groove depth of 5 μm as a height and an isosceles trapezoid having a groove width as a base and an angle of 30 degrees between the base and an oblique side with a groove depth of 1 μm to 15 μm as a height. The peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is formed by die casting.

In this embodiment, since the cross-sectional shape of the dynamic pressure groove is set within a range surrounded by the above-described isosceles triangle and isosceles trapezoid, the radial dynamic pressure groove is reliably formed by die casting. be able to. If the groove depth is smaller than 1 μm, it is within the range of variation in the processing of the mold and variation in the molding of the mold, causing a problem that a molded product shape cannot be obtained properly, which is not practical. If the groove depth is larger than 15 μm or the angle between the bottom and the oblique side exceeds 30 °, the molded product may be cut off by the undercut of the mold when the core pin is forcibly removed. I do. As a result, it has been experimentally confirmed that the groove cross-sectional shape of the molded product is lost and is not symmetrical within one groove cross-sectional shape, resulting in an undesirable shape as the cross-sectional shape of the dynamic pressure groove. Not preferred.

According to an embodiment of the present invention, a first surface and a second surface oppose each other to constitute a thrust bearing, and at least one of the first surface and the second surface has a dynamic pressure groove for generating a thrust dynamic pressure. The first surface and the second surface on which the dynamic pressure grooves are provided are made of a die-casting metal, and the cross-sectional shape of the dynamic pressure grooves has a groove width as a bottom and a groove depth of 1 μm to 30 μm. An isosceles triangle with a groove width of the bottom and 1 μm to 30 μm
The first surface and the second surface provided with the dynamic pressure grooves are formed by die-casting.

In this embodiment, since the cross-sectional shape of the dynamic pressure groove is within the range surrounded by the isosceles triangle and the rectangle, the dynamic pressure groove of the thrust bearing can be reliably die-cast. . If the groove depth is smaller than 1 μm, it is within the range of variation in the processing of the mold and variation in the molding of the mold, causing a problem that a molded product shape cannot be obtained properly, which is not practical. No, 3
If it exceeds 0 μm, it is not preferable because the molded product is shaved by the undercut portion.

As still another embodiment of the present invention,
A shaft and a bearing member having a bearing hole for rotatably arranging the shaft constitute a radial bearing, and at least one of a peripheral surface of the shaft and an inner peripheral surface of the bearing hole for generating a radial dynamic pressure. The peripheral surface of the shaft on which the dynamic pressure groove is provided or the inner peripheral surface of the bearing hole is made of die-casting metal, and the cross-sectional shape of the dynamic pressure groove has a groove width of the bottom side and 1 μm.
an isosceles triangle having a height of a groove depth of m to 15 μm;
With the groove width as the base and the groove depth of 1 μm to 15 μm as the height, the angle between the base and the hypotenuse is within a range surrounded by an isosceles trapezoid of 30 degrees, and the shaft having the dynamic pressure groove is provided. The peripheral surface or the inner peripheral surface of the bearing hole is formed by die casting. Moreover, a thrust bearing is constituted by the opposing first surface and second surface, and a dynamic pressure groove for generating thrust dynamic pressure is provided on at least one of the first surface and the second surface, and this thrust bearing is the same as the radial bearing. The first surface and the second surface provided with a dynamic pressure groove arranged in a core shape are made of a metal for die casting, and the cross-sectional shape of the dynamic pressure groove has a groove width as a base and a groove depth of 1 μm to 30 μm. Isosceles triangle with height as height and groove width as base,
A first surface having a dynamic pressure groove and a second surface having a dynamic pressure groove.
The surface is formed by die casting. In this embodiment, the dynamic pressure grooves for the radial bearing and the dynamic pressure grooves for the thrust bearing can be reliably die-cast.

When the dynamic pressure groove of the present invention is formed, a shaft or a bearing hole for rotatably disposing the shaft is formed on a surface of a die for forming a dynamic pressure groove for a radial bearing. Is an isosceles triangle having a groove width as a base and a groove depth of 1 μm to 15 μm as a height, a groove width as a base and a groove width as a base,
With a groove depth of 15 μm to 15 μm as a height, a projection for forming a dynamic pressure groove within a range surrounded by an isosceles trapezoid having an angle of 30 degrees between the bottom and the hypotenuse is provided, and corresponds to a dynamic pressure groove. The undercut portion on the mold is formed by forcibly removing the mold.

In this case, the surface of the mold member for forming a dynamic pressure groove for the shaft or a bearing hole for rotatably disposing the shaft is provided with the isosceles triangle and the isosceles trapezoid on the surface of the mold member. Since the projections for forming the dynamic pressure grooves within the enclosed range are provided, the undercut portion on the die forming corresponding to the dynamic pressure grooves can be reliably formed by forcibly removing the mold. If the groove depth is smaller than 1 μm, it will fall within the range of the processing variation of the mold and the variation in the mold forming,
When the core pin is forcibly extracted when the angle is larger than 15 μm or when the angle between the base and the oblique side exceeds 30 °, a problem that a molded product shape cannot be obtained properly occurs. In addition, the molded product may be shaved by the undercut portion of the mold. As a result, it has been experimentally confirmed that the groove cross-sectional shape of the molded product is lost and is not symmetrical within one groove cross-sectional shape, resulting in an undesirable shape as the cross-sectional shape of the dynamic pressure groove. Not preferred.

When the dynamic pressure groove of the present invention is formed, a thrust bearing is constituted by the opposing first surface and second surface, and at least one of the first surface and the second surface is used for generating thrust dynamic pressure. In order to provide the dynamic pressure groove, the sectional shape of the dynamic pressure groove is an isosceles triangle having a groove width as a base and a groove depth of 1 μm to 30 μm as a height, a groove width as a base and a groove width as 1 μm to 30 μm
A projection for molding is provided within a range surrounded by a rectangle whose height is the depth of the groove, and the dynamic pressure groove is formed by a mold.

In this case, the dynamic pressure groove for the thrust bearing can be reliably formed on at least one of the first surface and the second surface. If the groove depth is smaller than 1 μm,
There is a problem in that the processing variation of the mold and the variation in the molding of the mold fall within the range, and the shape of the molded product cannot be properly obtained. This is not preferable in that it is not realistic, and the groove depth is larger than 30 μm. This is not preferable because the molded product is shaved by the undercut portion.

The radial bearing and the thrust bearing which are the hydrodynamic bearing devices of the present invention described above are summarized as follows. 1. Regarding a hydrodynamic fluid bearing device having a radial bearing: (1) When forming a radial bearing with a shaft and a cylindrical bearing hole rotatably fitted to the shaft, at least one of the shaft and the bearing hole is formed by zinc die casting. Alternatively, it is formed of a die-casting metal such as tin die-cast, aluminum die-cast or magnesium die-cast, and formed by die-casting. (2) At least one cylindrical surface of the shaft or the cylindrical bearing hole has a spiral groove groove or a herringbone groove for generating a radial dynamic pressure. It is formed and provided at the same time as die casting. (3) The cross-sectional shape of the dynamic pressure groove is 1 μm with the groove width as the base.
It is surrounded by an isosceles triangle having a groove depth of m to 15 μm or less as a height and an isosceles trapezoid having a groove width as a base and a groove depth of 1 μm to 15 μm or less and an angle formed between the base and the hypotenuse of 30 degrees. Shape within the range of (4) An isosceles triangle having a groove width as a base and a groove depth of 1 μm to 15 μm or less as a cross section on the surface of the mold for molding the shaft or the bearing hole, and a groove width of 1 μm as a base.
Receiving a projection for forming a dynamic pressure groove within a range surrounded by an isosceles trapezoid having a groove depth of not more than 15 μm or less and an angle between the base and the hypotenuse being 30 degrees, and forming a mold corresponding to the groove The upper undercut portion is formed by forcibly removing the mold.

2. Regarding a hydrodynamic bearing device having a thrust bearing: (1) When forming a thrust bearing with two opposing surfaces, at least one of the two opposing surfaces is die-cast with zinc die-cast, tin die-cast, aluminum die-cast, or magnesium. And formed by die casting. (2) A spiral groove groove or a herringbone groove for generating thrust dynamic pressure is formed on at least one of the two opposing surfaces at the same time. (3) The cross-sectional shape of the dynamic pressure groove is 1 μm with the groove width as the base.
The shape falls within a range surrounded by an isosceles triangle having a groove depth of not more than 30 μm or less and a rectangle having a groove width of the bottom and a height of 1 μm to 30 μm or less. (4) A hydrodynamic bearing device having the above configuration and a method of manufacturing the same.

3. For hydrodynamic bearing devices with both radial and thrust bearings:

1. By forming the radial dynamic pressure bearing or the thrust dynamic pressure bearing by die casting, the following effects can be obtained, and the present invention is very effective when manufacturing the radial dynamic pressure bearing or the thrust dynamic pressure bearing or both. is there. (1) Production can be performed without using special production equipment. Therefore, bearings can be produced at low cost. (2) Grooves can be produced with high precision and high productivity. Therefore, bearings can be produced at low cost. (3) The formation of the groove does not particularly require complicated management required when forming by another method, and the management at the time of manufacturing is easy. (4) Since the radial bearing or the thrust bearing can be formed integrally with the housing, there is no need to fasten the bearing element and the housing, and the device can be formed compactly and inexpensively. (5) Since the radial bearing and the thrust bearing can be formed integrally, there is no need to particularly provide a seal between the radial bearing and the thrust bearing, which is necessary when the radial bearing and the thrust bearing are separately provided. Therefore, the apparatus can be configured compactly and inexpensively.

The present invention is not limited to the above-described embodiment. The motor of the above-described embodiment is a motor for continuously rotating a disk-shaped information recording medium. The device can of course be applied to other types of motors or devices having rotating parts other than motors.

Next, an example of the operation of the motor shown in FIG. 1 will be briefly described. The disc D is mounted on the turntable 7. By energizing the coil 12 of the stator portion 10b from the outside in a predetermined energizing pattern, a magnetic field is generated in the coil 12, and the magnetic lines of force interact with the magnetic lines of force passing from the permanent magnet 2 through the yoke 3 through the iron core 11. I do. As a result, the rotor portion 10a rotates about the shaft 4 with respect to the stator portion 10b.
Rotates continuously with the rotor portion 10a. At this time, the shaft 4 is connected to the radial bearing 2 of the hydrodynamic bearing device 100.
0 and the thrust bearing 22 smoothly rotates. That is, in the radial bearing 20 and the thrust bearing 22, the shaft 4
Since it is subjected to dynamic pressure by using a fluid such as oil, it can rotate stably. That is, the radial bearing 2
Since the dynamic pressure is generated between the dynamic pressure groove 20 shown in FIG. 2 of FIG. 2 and the outer peripheral surface of the shaft 4, the shaft 4 can rotate stably with respect to the housing 14 without tilting of the shaft. Further, a dynamic pressure of a fluid such as oil is generated between the dynamic pressure groove 40 of the thrust bearing 22 shown in FIG. 3 and the lower end surface of the shaft 4, so that the lower end surface of the shaft 4 floats from the thrust bearing surface 9. And can be stably supported. For this reason, when rotating the disk 6 about the center axis CL, the shaft 4 does not tilt, and can rotate stably without touching the shaft. In addition, as shown in FIG. 2, the radial bearing 20 has two dynamic pressure grooves 3.
Since 0 and 30 are formed, the shaft 4 can rotate stably without tilting.

[0043]

As described above, according to the present invention,
A hydrodynamic bearing device such as a radial dynamic pressure bearing or a thrust dynamic pressure bearing can be easily obtained at low cost and without requiring complicated management.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a motor to which a preferred embodiment of a hydrodynamic bearing device according to the present invention is applied.

FIG. 2 is a view showing an example of a radial bearing and a thrust bearing provided in a housing of the motor shown in FIG. 1;

FIG. 3 is a view showing a dynamic pressure groove of the thrust bearing of FIG. 2;

FIG. 4 is a view showing an example of a core pin (die) for forming the radial bearing and the thrust bearing of FIG. 2;

FIG. 5 is a view showing a lower end surface of the core pin of FIG. 4;

FIG. 6 is a diagram showing an example of a dynamic pressure groove of a radial bearing.

FIG. 7 is a diagram showing an example of a dynamic pressure groove of a radial bearing.

FIG. 8 is a sectional view showing an example of a core pin and a dynamic pressure groove.

FIG. 9 is a diagram showing an example of a motor including another preferred embodiment of the hydrodynamic bearing device of the present invention.

FIG. 10 is a diagram showing another embodiment of a radial bearing and a thrust bearing provided in a motor housing.

FIG. 11 is a view showing a dynamic pressure groove of the thrust bearing of FIG. 10;

FIG. 12 is a view showing an example of a core pin (die) for producing the radial bearing and the thrust bearing of FIG. 10;

FIG. 13 is a view showing a lower end surface of the core pin of FIG. 12;

[Explanation of symbols]

4 ... shaft, 6 ... disk (disk-shaped information recording medium), 9 ... thrust bearing surface, 10 ... motor,
14 ... housing (bearing member), 20 ... radial bearing, 22 ... thrust bearing, 30 ... dynamic pressure groove of radial bearing, 40 ... dynamic pressure groove of thrust bearing, 10
0: hydrodynamic bearing device, 200: core pin, 2
10: Projection of core pin, 220: Projection of core pin

Claims (8)

[Claims] A radial bearing is constituted by a shaft and a bearing member having a bearing hole for rotatably arranging the shaft. A radial bearing is formed on at least one of a peripheral surface of the shaft and an inner peripheral surface of the bearing hole. The dynamic pressure groove for radial dynamic pressure generation is provided, and the peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is made of metal for die-casting. An isosceles triangle having a height of a groove depth of 1 μm to 15 μm as a base, and an angle formed between the base and the hypotenuse with a groove width of a base of 1 μm to 15 μm and a height of 30 degrees. A hydrodynamic bearing device characterized by being formed in a range surrounded by an isosceles trapezoid, wherein a peripheral surface of a shaft provided with a hydrodynamic groove or an inner peripheral surface of a bearing hole is formed by die casting. 2. A thrust bearing comprising a first surface and a second surface facing each other, a dynamic pressure groove for generating thrust dynamic pressure is provided on at least one of the first surface and the second surface, and the dynamic pressure groove is provided. At least one of the first surface and the second surface provided is made of a metal for die casting, and the cross-sectional shape of the dynamic pressure groove is an isosceles having a groove width as a base and a groove depth of 1 μm to 30 μm as a height. A range surrounded by a triangle and a rectangle having a groove width as a base and a height of 1 μm to 30 μm as a groove depth, wherein at least one of the first surface and the second surface provided with the dynamic pressure grooves is die-cast. A hydrodynamic bearing device characterized by being formed of: 3. A radial bearing is constituted by a shaft and a bearing member having a bearing hole for rotatably arranging the shaft. A radial bearing is formed on at least one of a peripheral surface of the shaft and an inner peripheral surface of the bearing hole. The dynamic pressure groove for radial dynamic pressure generation is provided, and the peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is made of metal for die-casting. An isosceles triangle having a height of a groove depth of 1 μm to 15 μm as a base, and an angle formed between the base and the hypotenuse with a groove width of a base of 1 μm to 15 μm and a height of 30 degrees. The peripheral surface of the shaft provided with the dynamic pressure groove or the inner peripheral surface of the bearing hole is formed by die-casting within a range surrounded by an isosceles trapezoid, and the opposed first surface and second surface constitute a thrust bearing. And the first
A dynamic pressure groove for generating thrust dynamic pressure is provided on at least one of the surface and the second surface. The thrust bearing is arranged concentrically with the radial bearing, and the first surface and the second surface provided with the dynamic pressure groove. At least one of which is made of metal for die casting, the cross-sectional shape of the dynamic pressure groove is an isosceles triangle having a groove width as a base and a height of 1 μm to 30 μm as a groove depth, and a groove width as a base, And within a range surrounded by a rectangle having a height of 1 μm to 30 μm, and at least one of the first surface and the second surface provided with the dynamic pressure grooves is formed by die casting. Hydrodynamic bearing device. 4. The hydrodynamic bearing device according to claim 1, wherein the metal for die casting is selected from zinc, tin, aluminum, and magnesium. 5. The hydrodynamic bearing device according to claim 2, wherein the metal for die casting is selected from zinc, tin, aluminum, and magnesium. 6. The hydrodynamic bearing device according to claim 3, wherein the metal for die casting is selected from zinc, tin, aluminum, and magnesium. 7. On the peripheral surface of the shaft, or on the surface of a die for forming a dynamic pressure groove for a radial bearing with respect to a bearing hole for rotatably disposing the shaft, the groove width is defined as a base. An isosceles triangle having a groove depth of 1 μm to 15 μm as a height, and an isosceles triangle having a groove width of a base and an angle of 30 degrees between the base and the hypotenuse with a groove depth of 1 μm to 15 μm as a height A dynamic pressure groove forming projection within a range surrounded by a trapezoid is provided, and an undercut portion in the mold forming corresponding to the dynamic pressure groove is formed by forcibly removing the mold. Manufacturing method of hydrodynamic bearing device. 8. A mold for forming a thrust bearing with a first surface and a second surface facing each other and forming a dynamic pressure groove for generating a thrust dynamic pressure on at least one of the first surface and the second surface. On the surface of the substrate, the cross-sectional shape of the dynamic pressure groove has a groove width of the bottom and 1 μm
Forming an isosceles triangle having a groove depth of 3 to 30 μm in height and a rectangle having a groove width of the bottom and a rectangle having a groove depth of 1 to 30 μm in height; A method for manufacturing a hydrodynamic bearing device, wherein a pressure groove is formed by molding with a mold.