JP3159918B2 - Dynamic pressure bearing device and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydrodynamic bearing device and a method of manufacturing the same.

[0002]

2. Description of the Related Art A high-precision and high-speed rotation is required for a motor for driving a polygon mirror, a motor for driving a hard disk, and the like, and a dynamic pressure bearing device using a fluid such as air or oil is being used. As an example of a device using this dynamic pressure bearing device, there is, for example, a polygon mirror driving motor as shown in FIG. The polygon mirror driving motor shown in FIG. 1 constitutes a laser scanner in a digital copy, a laser printer, etc., and rotates at a high speed of 10,000 to 30,000 RPM or more. Possible air dynamic bearings are used.

The air dynamic pressure bearing type polygon mirror driving motor shown in FIG. 1 is a so-called inner rotor type (shaft rotation type) motor. That is, in FIG.
Several μm in the bearing (fixing member) 5
A rotor (rotating member) 2 is inserted with a gap of about 10 μm or more, and an air dynamic pressure formed by a spiral groove 15 formed on an outer peripheral surface 14 of the rotor 2 and an inner peripheral surface of the bearing 5. The rotor 4 is supported by a bearing 4 so as to be rotatable at high speed. Further, a drive coil 9 is fitted and fixed on the outer periphery of the central columnar portion of the base 8.
An annular magnet 10 for forming a magnetic circuit for driving is arranged so as to face the driving coil 9 in a circumferential direction.
The annular magnet 10 is disposed inside the rotor 2 via an iron yoke 19 and forms a motor driving unit together with the driving coil 9.

[0004] A convex portion 13 is provided at the tip (upper end in the figure) of the rotor 2, and the polygon mirror 1 is fitted to the convex portion 13. A balance plate 16 is coaxially mounted on the polygon mirror 1 via a wave spring 17, and a fixing screw 18 inserted from the balance plate 16 side is screwed to the protrusion 13 of the rotor 2. Thus, the polygon mirror 1 is fixed.

Further, a pair of annular magnets 11 and 12 are attached to the upper outer periphery of the central columnar portion of the base 8 and the inner periphery of the balance plate 16 so as to oppose each other. These annular magnets 11 and 12 are magnetized with their polarities reversed in the axial direction, thereby forming a magnetic thrust bearing.

When a predetermined drive voltage is applied to the drive coil 9, the polygon mirror 1 rotates together with the rotor 2, and the laser light converged on the polygon mirror 1 by the rotation of the polygon mirror 1 is an image (not shown). It scans on a recording medium. At this time, rotor 2
Is supported in the radial direction by the pressure generated between the rotor 2 and the bearing 5, and is levitated and supported by a magnetic thrust bearing including a pair of annular magnets 11 and 12.

Here, as a method of manufacturing the bearing (fixing member) 5 and the rotor (rotating member) 2, a method of manufacturing a round bar of stainless steel, ceramics or the like into a final required shape by a cutting method, a method of forging an aluminum material, or the like. There is known a method of manufacturing into a roughly required shape by cutting, and manufacturing into a final required shape by cutting.

[0008]

However, in the former for processing stainless steel and ceramics, the stainless steel and ceramics are difficult-to-process materials, so that the workability is extremely poor and cost increase is unavoidable. There is.

Further, in the latter case obtained by aluminum forging, the forging cost is high, and the dimensional accuracy of the forged product is poor, so that it takes time to finish the work. There was a problem that there was no.

Therefore, an aluminum die-casting method capable of easily manufacturing a shape close to the final required shape, minimizing finishing work because of the shape close to the final required shape, and thereby achieving cost reduction. It is possible to adopt.

However, in the aluminum die casting method, voids (bubbles) are unavoidable, and the voids are also present on the bearing surface, so that the rigidity of the bearing surface is reduced and various problems are caused. And cannot be provided as a product.

In order to enhance the slidability between the bearing surfaces, it is conceivable to form a lubricating resin layer on the surface corresponding to the bearing surface of the aluminum material formed by the aluminum die-casting method by, for example, painting. However, when such a lubricating resin layer is formed, when the lubricating resin layer dries, the voids generated on the surface corresponding to the bearing surface of the aluminum material expand and the bearing surface of the lubricating resin layer expands. Is swollen, resulting in burn-in and the like.

As described above, even if the bearing 5 and the rotor 2 are manufactured by the aluminum die-casting method in order to reduce the cost, the occurrence of voids on the surface corresponding to the bearing surface of the aluminum material cannot be avoided. There was a problem that the void made the product unworthy.

Accordingly, the present invention can easily manufacture the rotating member and the fixing member, reduce the cost, and eliminate the voids on the surface corresponding to the bearing surface of the rotating member and the fixing member, thereby improving quality and quality. It is an object of the present invention to provide a hydrodynamic bearing device capable of improving reliability and a method of manufacturing the same.

[0015]

According to a first aspect of the present invention, there is provided a hydrodynamic bearing device in which a bearing surface formed on a rotating member and a bearing surface formed on a fixed member are opposed to each other. In a dynamic pressure bearing device that rotatably supports the rotating member by a dynamic pressure effect generated between bearing surfaces, an aluminum drawing material used as a member constituting the bearing surface of the rotating member or the fixed member, and an aluminum die casting. And the other member constituting the rotating member or the fixed member integrally formed with the aluminum drawn material.

In order to achieve the above object, a dynamic pressure bearing device according to a second aspect of the present invention is characterized in that the shape of the aluminum drawn material according to the first aspect is a cylindrical round bar shape or a hollow cylindrical shape. And

According to a third aspect of the present invention, there is provided a hydrodynamic bearing device, wherein the other member includes a fixing frame forming a part of the fixing member or a fixing frame having a radiation fin. It is characterized by doing.

In order to achieve the above object, a dynamic pressure bearing device according to a fourth aspect is characterized in that the other member according to the first aspect is a motor rotor mounting portion constituting a part of a rotating member. I have.

In order to achieve the above object, a dynamic pressure bearing device according to a fifth aspect is characterized in that the other member according to the first aspect is a mounting portion for a mirror which constitutes a part of a rotating member. .

In order to achieve the above object, a dynamic pressure bearing device according to a sixth aspect is characterized in that a lubricating resin layer is provided on the bearing surface according to the first aspect.

According to a seventh aspect of the present invention, there is provided a method of manufacturing a dynamic pressure bearing device, wherein a bearing surface formed on a rotating member and a bearing surface formed on a fixed member are opposed to each other. In a method of manufacturing a hydrodynamic bearing device that rotatably supports the rotating member by a dynamic pressure effect generated in the method, the member constituting the bearing surface of the rotating member or the fixed member is formed of a drawn aluminum material, Another member constituting the rotating member or the fixed member is formed integrally with the aluminum extraction material by aluminum die casting.

According to the dynamic pressure bearing device and the method of manufacturing the same according to the present invention, when the member constituting the bearing surface of the rotating member or the fixed member is made of a drawn aluminum material, the drawn aluminum material is used. Since there is no void, no void is present on the bearing surface formed of the aluminum drawn material. Further, when other members constituting the rotating member or the fixed member are integrally formed with the aluminum drawing material by aluminum die casting, a shape close to the final required shape can be easily obtained by this aluminum die casting, and Finishing work is minimized because the shape is close to the final required shape.

In particular, according to the dynamic pressure bearing device of the sixth aspect, the lubricating resin layer is provided on the bearing surface, so that the lubricating resin layer enhances the slidability.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. As an application form of the present invention, there is a polygon mirror driving motor in FIG. 1, but the entire structure of the motor has already been described in the section of the prior art, so that the description thereof will be omitted. explain.

The dynamic pressure bearing device shown in FIG. 2 is an inner rotor type (shaft rotation type) air dynamic pressure bearing device, in which a bearing (stator) 32 as a fixed member and a rotor 30 as a rotating member are arranged. Are rotatably supported by air dynamic pressure. That is, the rotor 3
A dynamic bearing 35 is constituted by an outer peripheral surface 30c (more precisely, an outer peripheral surface of a lubricating resin layer 34 described later) 30c and an inner peripheral surface 32c of the bearing 32.

The bearing 32 is made of an aluminum material such as aluminum or an aluminum alloy. The inner peripheral surface (bearing surface) of the bearing 32 is subjected to electroless nickel plating to prevent corrosion and wear.

As shown in FIG. 4, the rotor 30 has a rotor material 36 serving as a base material, an alumite film 33 formed on the surface of the rotor material 36, and a surface corresponding to the bearing surface of the alumite film 33. And a lubricating resin layer 34 formed on the substrate. It should be noted that in FIG. 4, the dynamic pressure generating grooves 3
1 is omitted.

As shown in FIG. 3, the rotor material 36 constitutes a body of the rotor material 36 and also constitutes a bearing surface, and a polygon mirror provided at the upper end of the member 36a in the drawing and described above. 1 is mounted on the mirror mounting portion 36b. Member 3
Numeral 6a is a drawn aluminum member made of aluminum, an aluminum alloy or the like and having a hollow cylindrical shape. Therefore, no void exists in this member 36a. On the other hand, the mirror mounting portion 36b is formed integrally with the aluminum extraction material 36a by an aluminum die casting method.

The aluminum material forming the aluminum extraction member 36a and the mirror mounting portion 36b has a thermal conductivity of 240 W · m ⁻¹ · K ⁻¹ , for example, a SUS thermal conductivity (15 W · m ^{−). 1} · K ^-1 ), thermal conductivity of ceramic (20
W · m ^-1 · K ^-1 ), and thus has excellent heat dissipation.

The alumite film 33 can improve the adhesion and has a rust-preventing ability against the aluminum material constituting the rotor material 36.

The lubricating resin layer 34 is made of, for example, a polyamideimide 34 in which PTFE (polytetrafluoroethylene) is dispersed.
Is coated with a thickness of 3 μm or more, and has excellent wear resistance and seizure resistance.

In order to obtain the rotor 30 having the alumite coating 33 and the lubricating resin layer 34, first, an aluminum drawn material 36a having a hollow cylindrical shape is prepared, and then this aluminum drawn material 36a is used for a mirror. It is inserted into a predetermined position of a die-casting die having a space corresponding to (coincident with) the shape of the mounting part 36b, the molten aluminum is poured into the die, and the aluminum extraction material 36a and the mirror mounting part 36b are integrally formed. . Next, the surface corresponding to the bearing surface of the rotor material 36 is formed by, for example, wet etching, sand blasting, or the like so that the adhesion between the rotor material 36 and the lubricating resin layer 34 formed by such an aluminum die-casting method is increased. Surface roughness of 3s (J
Surface roughness specified in IS B0031) or more, and then applied to the surface of the rotor material 36 by, for example, coating, sulfuric acid bath, spraying or the like.
Form 3

Accordingly, the alumite film 33 prevents rust of the rotor material 36 made of the aluminum material and enhances the adhesion between the rotor material 36 and a lubricating resin layer 34 described later. The adhesion between the rotor material 36 and the lubricating resin layer 34 is further enhanced by reducing the surface roughness of the rotor material 36.

Next, a polyamideimide 34 in which PTFE is dispersed is adhered to a surface corresponding to the bearing surface of the alumite film 33 by, for example, spraying, brushing, dipping, molding or the like so as to have a sufficient thickness. The polyamideimide 34 in which PTFE is dispersed is dried at a high temperature, and then the polyamideimide 34 is dried.
The minimum thickness of the polyamideimide 34 is 3 μm.
If the groove 31 for dynamic pressure generation is formed to have a predetermined shape and depth so as to have a predetermined shape and depth, for example, the polyamideimide 34 in which PTFE is dispersed as shown in FIG. A rotor 30 having 33 will be obtained.

In the present embodiment, the thickness of the polyamideimide 34 coated as described above is set to be 3 μm or more. The reason will be described with reference to FIG. FIG. 5 shows that the surface roughness of the drawn aluminum material is 3 s, an alumite film similar to the above is formed on the aluminum alumite film, a polyamideimide in which a fluororesin is dispersed is coated on the alumite film, and the coating thickness is determined by lace processing. Seven types of bearings each having a thickness of 1 to 7 μm were obtained, and ten motors were prepared for each type. For each motor operation, the polyamideimide coating surface was forced into contact with the facing surface of the bearing 32 100 times. This shows the number of motors that have resulted in burn-in.

As apparent from FIG. 5, when the coating thickness is smaller than 3 μm, seizure occurs due to contact during operation, and when it is 3 μm or more, seizure does not occur. That is, if the thickness of the coated polyamideimide is 3 μm or more as in the present embodiment, image sticking is prevented.

In this embodiment, a resin containing polyamideimide as a main component is used for the lubricating resin layer as described above. The reason will be described with reference to FIG. FIG. 6 shows two types of motors (No. 5, No. 6) using polyamideimide as the lubricating resin layer 34 and four types of motors (No. 1 to No. 4) using epoxy resin. 4 shows a wear result after each motor is operated. In the experiment, as shown in the figure, an epoxy resin manufactured by Toyo Dry-Lube Co., Ltd. and a polyamideimide manufactured by Shikoku Chemicals Co., Ltd. were used.

As is clear from FIG. 6, it can be confirmed that the use of polyamideimide as the lubricating resin layer is superior to the use of epoxy resin in abrasion resistance.

As described above, in the present embodiment, since the member 36a constituting the bearing surface of the rotor 30 is made of an aluminum drawn material having no voids, the bearing of the aluminum drawn material 36a is used. It is possible to prevent various problems caused by voids on the surface.

Also, since the mirror mounting portion 36b as another member constituting the rotor 30 is formed integrally with the aluminum drawn material 36a by the aluminum die casting method, the final required shape is formed by the aluminum die casting method. A shape close to the final required shape can be easily manufactured, and the finish processing can be minimized by the shape close to the final required shape. A round bar is made into the final required shape by cutting method, and an aluminum material is roughly required by forging method Compared to conventional technologies such as forming into the final required shape by cutting and cutting,
The rotor 30 can be obtained more easily.

Further, since the lubricating resin layer 34 is formed on the outer peripheral surface (bearing surface) of the rotor 30, the abrasion resistance and seizure resistance of the bearing surface can be improved by the lubricating resin layer 34. It is possible to prevent the bearing surfaces from contacting each other at the time of start-up and stopping, and to prevent the bearing surfaces from contacting each other due to a large disturbance and being damaged, for example, seizure during use. I have.

At this time, since the member 36a constituting the bearing surface of the rotor 30 is made of an aluminum drawn material having no void as described above, the void 36 is not formed when the lubricating resin layer 34 is dried. Is prevented from expanding and the bearing surface of the lubricating resin layer 34 is expanded.

Further, the lubricating resin layer 34 has poor heat conduction and the heat generated in the bearing portion is not radiated well but is confined. Since the aluminum material having a high thermal conductivity is used, the heat generated in the bearing portion can be radiated satisfactorily by the aluminum material 36, and the fear of adversely affecting, for example, the motor drive portion as other members in the periphery can be reduced. I have. Moreover, since the aluminum material 36 is excellent in workability, there is also an effect that the work can be easily performed.

The rotor material 36 may be made of gold, silver or copper having a higher thermal conductivity than aluminum material, but these are not preferable because they are very expensive.

FIG. 7 shows another embodiment.
In this embodiment, the bearing 32 shown in FIG.
The bearing 32 includes a member 32a that forms the inner circumferential side of the body and also forms a bearing surface, and a member 32b that forms the outer circumferential side of the body of the bearing 32 and forms a frame. The member 32a is a hollow cylindrical aluminum drawn material made of aluminum, an aluminum alloy or the like, and the member 32b is formed integrally with the aluminum drawn material 32a by an aluminum die casting method.

An alumite film and a lubricating resin layer are formed on the inner peripheral surface (bearing surface) of the bearing 32 in the same manner as described in the previous embodiment. The formation of the layer and the molding of the bearing 32 by the aluminum die-casting method are also performed in the same manner as in the above-described embodiment.

Therefore, it is needless to say that the same effect as in the previous embodiment can be obtained.

FIG. 8 shows still another embodiment. The air dynamic pressure bearing type polygon mirror driving motor shown in FIG. 8 is a so-called outer rotor type (fixed shaft type).
It is a motor. This air dynamic pressure bearing motor is generally composed of a fixed group (stator group) 51 and a rotating group (rotor group) 52 fitted into the fixed group 51 from above in the figure. .

The fixing set 51 includes a fixing member 53 which is a main part of the fixing set 51. This fixing member 5
9, reference numeral 3 denotes a disk-shaped fixing frame 55, a center fixing shaft 54 which is erected substantially at the center of the fixing frame 55 and constitutes a bearing surface, and the fixing frame 55 shown in FIG. A plurality of heat dissipating fins 55
a.

As shown in FIG. 10, the center fixing shaft 54 is made of aluminum, an aluminum alloy, or the like, and is made of an aluminum drawn material having a cylindrical round bar shape. The fixing frame 55 and the radiation fin 55a are , Aluminum die-casting method by aluminum die-casting method (center fixed shaft)
It is formed integrally with 54.

That is, for such a fixing member 53, a columnar aluminum extraction member 54 is prepared, and this aluminum extraction member 54 corresponds to the shape of the fixing frame 55 and the radiation fins 55a. ) It can be obtained by inserting into a predetermined position of a die-casting die having a space formed therein, pouring the molten aluminum into the die, and integrally molding the aluminum drawing material 54, the fixing frame 55, and the radiation fins 55a. ing.

Now, returning to FIG. 8 again,
Has a bearing holder 56 fixed to the fixing frame 55 so as to surround the center fixed shaft 54 in a cylindrical shape at a certain distance in the radial direction from the outer peripheral surface. A stator core 57 is fitted around the outer periphery of the bearing holder 56, and a driving coil 58 is wound around a salient pole of the stator core 57. The center fixed shaft 54
On the outer peripheral surface, a herringbone type dynamic pressure generating groove 59 is annularly concavely divided into two blocks in the axial direction.

The outer peripheral surface (bearing surface) of the center fixed shaft 54
The alumite film and the lubricating resin layer are formed in the same manner as in the above-described embodiment.

The rotating set 52 includes a rotating member 60 which is a main part of the rotating set 52. This rotating member 60
Has a hollow cylindrical portion 61 that forms a hollow cylindrical shape and constitutes a bearing surface, and a rotation protruding from a substantially central portion of the outer peripheral surface of the hollow cylindrical portion 61 in the axial direction so as to form a cup shape. It has a body attachment part 62. This rotating body mounting part 6
Numeral 2 constitutes a motor rotor mounting portion for mounting a drive magnet, which will be described later, and a mirror mounting portion for mounting a polygon mirror. The hollow cylindrical portion 6
1 is rotatably mounted on the outside of the center fixed shaft 54 of the above-described fixed set 51. Then, between the outer peripheral surface (bearing surface) 54a of the center fixed shaft 54 and the inner peripheral surface (bearing surface) 61a of the hollow cylindrical portion 61, a dynamic bearing is generated to form a radial bearing. Have been.

The center fixed shaft 54 is also provided with an air supply hole 63 extending in the axial direction from the shaft end (upper end in the figure) of the center fixed shaft 54.
Is open toward the outside of the center fixed shaft 54 at a portion between the dynamic pressure generating grooves 59 of the two blocks. Further, an outer peripheral portion of the shaft end portion (upper end portion in the figure) of the center fixed shaft 54 projects axially by a predetermined amount, and a fixed-side magnet 64 for thrust floating is annularly mounted on an inner peripheral wall of the projected portion. Have been.

On the other hand, a flat hexagonal polygon mirror 65 as a rotating plate is fitted around the outer periphery of the hollow cylindrical portion 61 of the rotating set 52 on the base side (upper side in the figure) so as to constitute the rotating plate. I have. The polygon mirror 65 includes a holding portion 6 extending radially outward from the hollow cylindrical portion 61.
1b, the screw 85 is screwed into the base (upper end in the figure) of the hollow cylindrical portion 61, and the holding plate 66 is pressed downward in the figure, whereby the polygon mirror 65 and the holding plate 66 are pressed. Is fixed to the hollow cylindrical portion 61.

A fine air orifice 67 having a predetermined air flow resistance is formed in the center of the pressing plate 66 of the rotating set 52 so as to penetrate in the axial direction as a damper means. The shock in the axial direction on the rotating set 52 is reduced by the damper action by the resistance. Further, the air inside the rotating set 52 is supplied to the portion between the dynamic pressure generating grooves 59 by the air supply hole 63, and the air is supplied to the dynamic pressure generating groove 5.
Due to the pumping action of 9, 59, it is made to flow in the axially outward vertical direction in the figure and is discharged to the outside.

A rotating side magnet 68 for thrust floating is annularly mounted around the air orifice 67 at the lower end surface in the drawing of the pressing plate 66 of the rotating set 52. The rotating magnet 68 is magnetized in the axial direction (vertical direction in the drawing) so as to mutually generate a magnetic attraction with the fixed magnet 64 on the center fixed shaft 54 side. The rotating set 52 is configured to be held in a state of floating by a predetermined amount in the thrust direction.

The cup-shaped rotator mounting portion 62 of the rotator set 52 extends from the holding portion 61b, and extends between the drive coil 58 and the polygon mirror 65 in the axial direction from the two members 58 and 65. Are formed so as to face each other with a space therebetween. That is, the rotating body mounting portion 6
Numeral 2 is arranged so as to partition a space inside the rotor in which the drive coil 58 is arranged and a space outside the rotor in which the polygon mirror 65 is arranged.

A drive magnet 70 is annularly mounted on the inner peripheral wall surface of the cup-shaped rotating body mounting portion 62 via a back yoke 69 made of a magnetic material. The drive magnet 70 is disposed so as to face the outer surface of the stator core 57 in the radial direction.

When the rotating set 52 rotates, an air film is formed between the bearing surfaces 54a and 61a due to the pumping action of the dynamic pressure generating grooves 59 and 59 with the rotation, whereby pressure is generated. The rotating set 52 is supported in the radial direction.

As described above, in the present embodiment, the center fixed shaft 54 is made of an aluminum drawn material having a round bar shape,
The fixing frame 55 and the radiating fins 55a are extracted from the aluminum by the aluminum die casting method (center fixing shaft).
Since the alumite film and the lubricating resin layer are formed on the outer peripheral surface of the center fixed shaft 54 in addition to being formed integrally with the center fixed shaft 54, the same effect as the above embodiment can be obtained.

In the present embodiment, the center fixing shaft 54 made of a drawn aluminum material, the fixing frame 55, and the radiating fins 55a are integrally formed by the aluminum die casting method. However, the aluminum die casting method is used. , Center fixed shaft 5 made of drawn aluminum
4 and the fixing frame 55 are integrally formed,
It is also possible to replace with a configuration in which 5a is screwed to the fixing frame 55. However, this configuration increases the assembly cost as compared with the present embodiment.

FIG. 11 shows another embodiment. In this embodiment, a hollow cylindrical portion 61 shown in FIG. 8 is made of aluminum, an aluminum alloy, or the like, and is made of an aluminum drawn material having a hollow cylindrical shape. The rotating body mounting portion 62 is formed integrally with the aluminum extraction member 61 by an aluminum die casting method.

An alumite film and a lubricating resin layer are formed on the inner peripheral surface (bearing surface) of the hollow cylindrical portion 61 in the same manner as described in the previous embodiment. The formation of the conductive resin layer and the molding of the rotating member 61 by the aluminum die-casting method are performed in the same manner as in the above-described embodiment.

Therefore, it is needless to say that the same effects as those of the above embodiment can be obtained.

As shown in FIG. 7, the hollow cylindrical portion 61 is made of a drawn aluminum material that forms the inner peripheral side of the body and also forms the bearing surface. And a member constituting a motor rotor mounting portion to which the driving magnet 70 is mounted and a mirror mounting portion to which the polygon mirror 65 is mounted. The hollow cylindrical portion and the rotating body mounting portion are formed by an aluminum die casting method. It may be formed integrally.

Also, the member 32a described in FIG.
As shown in FIG. 1, the entire body of the bearing 32 is formed and a member forming the bearing surface is formed. The member 32 b is formed as a frame forming member, and these members are integrally formed by an aluminum die casting method. You may do it.

In each of the above embodiments, FIG.
As shown in FIGS. 7, 10, and 11, annular cutouts are formed in the aluminum drawn members 36a, 32a, 54, and 61 by, for example, machining, and are integrally formed by an aluminum die casting method. The connection with the member is improved.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say, for example, even if the alumite film is replaced with a chromium film or a silane coupling agent film by a chromate treatment, like the alumite film, the improvement of the adhesion and the rust prevention against the aluminum material can be achieved. Can be planned. Further, in the above embodiment, such a coating is formed on the entire surface of the base material, but may be formed only on the surface corresponding to the bearing surface of the base material.

In the above embodiment, the lubricating resin layer is made of polyamide-imide in which PTFE is dispersed. However, the present invention is not limited to this, and an epoxy resin or the like may be used. good.

Further, the dynamic pressure bearing device of the above-described embodiment can be used as a motor for rotating various rotating plates such as a magnetic disk and an optical disk other than a polygon mirror, a motor using a fluid such as oil other than air, and a motor. The same can be applied to devices other than motors.

[0073]

As described above, according to the dynamic pressure bearing device and the method of manufacturing the same of the present invention, the member forming the bearing surface of the rotating member or the fixed member is made of a drawn aluminum material having no void. Therefore, it is possible to prevent various problems caused by voids in the bearing surface formed of the aluminum drawn material, and to improve quality and reliability. In addition, other members constituting the rotating member or the fixed member are formed integrally with the drawn aluminum material by aluminum die casting, and by this aluminum die casting, a shape close to the final required shape can be easily manufactured, and Because it is a shape close to the required shape, it is possible to minimize finishing work, so that a round bar is made into the final required shape by cutting method,
Compared to conventional technologies such as forging an aluminum material into a roughly required shape by forging and cutting it to a final required shape, a rotating member or a fixed member can be obtained more easily, and cost reduction can be achieved. Become.

In the dynamic pressure bearing device according to the sixth aspect, a lubricating resin layer is provided on the bearing surface so that the lubricating resin layer can enhance the slidability. Thus, the effects of the present invention can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a half transverse sectional view showing an air dynamic pressure bearing type inner rotor type motor to which the present invention is applied.

FIG. 2 is an exploded transverse sectional view showing the dynamic pressure bearing device shown in FIG.

FIG. 3 is a transverse sectional view showing a main body of the rotating member shown in FIG. 2;

FIG. 4 is a cross-sectional view illustrating the rotating member illustrated in FIG. 2;

FIG. 5 is a diagram showing a relationship between a coating thickness of polyamide imide and burning due to contact during operation.

FIG. 6 is a diagram showing the wear characteristics of a coating resin.

FIG. 7 is a cross-sectional view showing another embodiment of the fixing member shown in FIG.

FIG. 8 is a half transverse sectional view showing an outer rotor type motor of an air dynamic pressure bearing type to which the present invention is applied.

FIG. 9 is a perspective view showing a fixing member shown in FIG.

FIG. 10 is a transverse sectional view showing the fixing member shown in FIGS. 8 and 9;

FIG. 11 is a cross-sectional view showing another embodiment of the rotating member shown in FIG.

[Explanation of symbols]

 30c, 61a Bearing surface of rotating member 32, 53 Fixing member 32a, 36a, 54, 61 Aluminum extraction material 32b, 36b, 55, 55a, 62 Other members 32c, 54a Bearing surface of fixing member 34 Lubricant resin layer 36 (30), 60 rotating member

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16C 17/00-17/26 F16C 33/00-33/28 G02B 26/10 H02K 5/00-5 / 26 H02K 7/00-7/20

Claims (7)

(57) [Claims] A dynamic pressure bearing device in which a bearing surface formed on a rotating member and a bearing surface formed on a fixed member are opposed to each other, and the rotating member is rotatably supported by a dynamic pressure action generated between the bearing surfaces. In the above, an aluminum drawn material used as a member constituting the bearing surface of the rotating member or the fixed member, and the rotating member or the fixed member integrally formed with the aluminum drawn material by aluminum die casting. A dynamic pressure bearing device comprising: 2. The hydrodynamic bearing device according to claim 1, wherein the shape of the drawn aluminum material is a cylindrical round bar shape or a hollow cylindrical shape. 3. The dynamic pressure bearing device according to claim 1, wherein the other member is a fixing frame that forms a part of the fixing member or a fixing frame with a radiation fin. 4. The hydrodynamic bearing device according to claim 1, wherein the other member is a motor rotor mounting portion that forms a part of the rotating member. 5. The dynamic pressure bearing device according to claim 1, wherein the other member is a mirror mounting portion that forms a part of the rotating member. 6. A hydrodynamic bearing device, wherein a lubricating resin layer is provided on the bearing surface according to claim 1. 7. A dynamic bearing device in which a bearing surface formed on a rotating member and a bearing surface formed on a fixed member are opposed to each other, and the rotating member is rotatably supported by a dynamic pressure action generated between the bearing surfaces. In the method of manufacturing, the member forming the bearing surface of the rotating member or the fixed member is formed of a drawn aluminum material, and the other member forming the rotating member or the fixed member is formed of the aluminum by aluminum die casting. A method for manufacturing a dynamic pressure bearing device, wherein the method is formed integrally with a drawn material.