JP2000018239A - Manufacture of dynamic pressure bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a groove for dynamic pressure generation highly accurately and efficiently, while forming a good lubricating coating surface to the dynamic pressure surface in a shaft body or a shaft fitting body. SOLUTION: At least on one side surface of both dynamic pressure bearing surfaces of a shaft body 21 and a shaft fitting body 31, a lubricating membrane is formed by an electrodepositing coating, and a groove for dynamic pressure generation 25 is formed to the electro-depositing coating membrane by an Exima-rasar processing. As a result, the lubricating membrane can be obtained in the all peripheral even layer thickness by the even coating operation of the electrodepositing coating, and at the same time, the groove processing can be a carried out at a high accuracy by a simple process, without generating burrs as in the conventional mechanical processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of a dynamic pressure bearing device in which a dynamic pressure is generated in a lubricating fluid, and the shaft pressure and the shaft fitting body are relatively rotatably supported by the dynamic pressure. About the method.

[0002]

2. Description of the Related Art In recent years, polygon mirrors, magnetic disks,
Various proposals have been made for hydrodynamic bearing motors that rotationally drive various rotating plates such as optical disks. In this hydrodynamic bearing device, the hydrodynamic bearing surface on the shaft body side and the hydrodynamic bearing surface on the shaft fitting body side are provided so as to oppose each other in the radial direction with a predetermined gap therebetween. A dynamic pressure bearing is formed. A groove for generating dynamic pressure is formed on one of the two opposed dynamic pressure bearing surfaces, so that a lubricating fluid such as air or oil injected into the dynamic pressure bearing portion is rotated during rotation. The pressure is generated by the pumping action of the pressure generating groove, and both members of the shaft body and the shaft fitting body are relatively rotatably supported by the dynamic pressure of the lubricating fluid.

In general, a lubricating paint is applied to one surface of both hydrodynamic bearing surfaces of the shaft body or the shaft fitting body in such a hydrodynamic bearing device, and a plating is applied to the other surface. And both are used in combination.

For example, in order to apply a lubricating paint to a shaft fitting body, first, a shaft fitting body as shown in FIG. 5A is cast or die-cast using aluminum and an aluminum alloy material. Is formed. Then, as shown in FIG. 5B, a base treatment 2 such as a chromate treatment or an anodic oxidation treatment for improving corrosion resistance and coating adhesion is performed, and a masking 3 is applied to a part of the outer surface. , And as shown in FIG.
For the inner peripheral surface of the blank 1, for example, PTFE
After applying and drying the (polytetrafluoroethylene) -containing lubricating paint 4 by spraying or the like, the same spray coating is repeated three to five times again to perform thick coating. The reason why such thick coating is performed is that there is foaming or unevenness in the layer thickness of the coating, and the material having the uneven coating is laced as shown in FIG. Processing 5 and the like are performed to finish the coating 4 so that the thickness of the coating 4 becomes about 15 microns, and to perform the accuracy of the inner diameter dimension. The same applies when a lubricating paint is applied to the shaft body side.

[0005] On the other hand, when plating the dynamic pressure bearing surface on the shaft body side, if there is a dynamic pressure generating groove, the dynamic pressure generating groove is formed before plating. That is, the blank 6 shown in FIG.
As shown in FIG. 6B, masking printing 7 is applied to portions other than the portion where the dynamic pressure generating groove is formed, and as shown in FIG. , The dynamic pressure generating groove 9 is processed.

[0006] Next, a plating process is started, and pretreatments such as degreasing and activation are performed as shown in FIG. 6D, and then, as shown in FIG. The end face is covered with a cap 8 to replace the surface with zinc, and a plating process such as electroless nickel plating is performed as shown in FIG.

[0007]

However, such a conventional hydrodynamic bearing device and its manufacturing method have the following problems. First, in the lubricating paint coating process, the coating process itself takes time to perform thick coating, and a finishing process such as lace processing for forming a uniform thickness must be performed. Further, even if the outer diameter dimension can be ensured by the lace processing, the axial center deviation may remain, and a predetermined film thickness cannot be secured uniformly. As a result, the fixing member and the rotating member may come into contact with each other to cause a galling phenomenon.

On the other hand, in the case of plating, a very large number of steps (approximately 50 steps) have to be performed, so that the conventional hydrodynamic bearing device has low productivity and high product cost. There is a problem. In addition, the plating treatment is not sufficiently durable against corrosion, and the surface grows in a granular manner, so that the surface roughness (smoothness) is not good. In the case of a requesting device, this can be a major problem.

Furthermore, in forming the grooves for generating dynamic pressure, a mechanical cutting step is usually employed.
In that case, since burrs are generated, as described above, the fixing member and the rotating member may cause a contact and galling phenomenon.

Accordingly, the present invention is to provide a dynamic pressure bearing surface which is simple and has high quality and excellent durability.
An object of the present invention is to provide a method of manufacturing a dynamic pressure bearing device capable of forming a dynamic pressure generating groove with high precision and efficiency on the dynamic pressure bearing surface.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, an outer peripheral surface of a shaft body and a shaft fitting body mounted rotatably relative to the shaft body are provided. At least one pair of radially opposed dynamic pressure bearing surfaces is formed by the peripheral surface, and a dynamic pressure generating groove of a predetermined shape is formed on one of the dynamic pressure bearing surfaces of the shaft body and the shaft fitting body. Forming a lubricating coating on at least one of the dynamic pressure bearing surfaces of the shaft body and the shaft fitting body by electrodeposition coating, the method comprising: On the surface where the lubricating film was formed by painting,
Forming the dynamic pressure generating groove by excimer laser processing.

According to the second aspect of the present invention, the processing depth of the groove formed by the excimer laser processing step is set to be smaller than the thickness of the electrodeposition lubricating film.

Further, according to the third aspect of the present invention, in the excimer laser processing step of the first aspect, the lubricating film is covered with a masking member having a predetermined shape in which a hole corresponding to the dynamic pressure generating groove is formed. It is done as follows.

Further, in the fourth aspect of the present invention, in the excimer laser processing step of the first aspect, the optical axis of the laser beam for performing the excimer laser processing is adjusted to a shaft body or a shaft fitting body which is a workpiece. It is set so as to form a predetermined angle with respect to the radial direction.

According to the first aspect of the present invention,
A uniform lubricating film can be easily obtained with a uniform layer thickness all over the circumference by the uniform coating action of electrodeposition coating.
Since the lubricating particles (PTFE) float on the surface of the coating at the time of electrodeposition coating, the lubricating particles (PTFE) are formed to have extremely good lubricity, and the bearing characteristics are improved.

Further, as in the invention according to claim 1,
If a dynamic pressure generating groove is formed by excimer laser processing on a lubricating film formed by electrodeposition coating, high-precision groove processing can be performed in a simple process without generating burrs unlike conventional machining. Will be

At this time, as in the second aspect of the present invention,
If the groove processing depth by the excimer laser is set to be smaller than the film thickness of the electrodeposition coating lubricating film, the surface of the shaft body or the shaft fitting body itself will not be exposed. Becomes unnecessary.

Further, if laser processing is performed using a masking member as in the third aspect of the present invention, groove processing by laser is performed extremely efficiently.

Further, if the grooves are formed by inclining the laser beam as in the invention of claim 4, it is easy to incline the grooves in a direction suitable for generating the dynamic pressure. Done.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below. Prior to that, the structure of a shaft-rotating polygon mirror driving motor having an air dynamic pressure bearing to which the present invention is applied will be described with reference to the drawings. It is explained based on.

FIG. 4 shows an example of an outer rotor type motor provided with a fixed shaft type air dynamic pressure bearing device for rotationally driving a polygon mirror. This air dynamic pressure bearing motor includes a stator set 20 as a fixing member assembled on the frame 10 side,
And a rotor set 30 as a rotating member fitted so as to be fitted from the upper side in the figure. Among these, the stator set 20 is a fixed shaft (shaft) mounted so as to stand upright at a substantially center position of the frame 10. And a bearing holder 22 that surrounds the fixed shaft 21 in a cylindrical shape at a constant distance in the radial direction from the outer peripheral surface of the fixed shaft 21. A stator core 23 is fitted around the outer periphery of the bearing holder 22, and a drive coil 24 is wound around salient pole portions of the stator core 23.

On the outer peripheral surface of the fixed shaft 21, a herringbone type dynamic pressure generating groove 25 is axially divided into two blocks and is annularly recessed. , 25, a cylindrical body (shaft fitting body) 31 of the rotor set 30 is rotatably mounted with a gap of several μm to several tens of μm. The air bearing is generated between the outer peripheral surface of the fixed shaft 21 and the inner peripheral surface of the cylindrical body 31 of the rotor set 30 to form a radial bearing. The fixed shaft 21 has an air supply hole 26 extending in the axial direction from a shaft end (upper end in the figure) of the fixed shaft 21, and the air supply hole 26 generates the dynamic pressure of the two blocks. Groove 2
The portion between 5, 25 is open toward the outside of the fixed shaft 21.

Further, an outer peripheral portion of the shaft end (upper end in the figure) of the fixed shaft 21 projects axially by a predetermined amount, and a fixed-side magnet 27 for thrust floating is annularly formed on an inner peripheral wall of the projected portion. It is attached to. On the other hand, a porous air orifice 32 having a predetermined air flow resistance penetrates axially as a damper means at a center portion of the cylindrical body 31 of the rotor set 30 at a base side (upper end side in the figure). The damping action of the air orifice 32 due to the airflow resistance reduces the impact on the rotor set 30 in the axial direction. The air inside the rotor set 30 is supplied to the portion between the dynamic pressure generating grooves 25 by the air supply holes 26, and the pumping action of the dynamic pressure generating grooves 25, 25 causes the air to flow outward in the vertical direction in the drawing. And discharged to the outside.

Further, around the air orifice 32, a rotary magnet 33 for thrust floating is annularly mounted. The rotating magnet 33 is magnetized in the axial direction (vertical direction in the drawing) so as to mutually generate a magnetic attraction with the fixed magnet 27 on the fixed shaft 21. The set 30 is configured to be held in a state of floating by a predetermined amount in the thrust direction.

On the other hand, a flat hexagonal polygon mirror 34 as a rotary plate is fitted around the outer periphery of the cylindrical body 31 of the rotor set 30 on the base side (upper end side in the figure) so as to form a rotary plate. I have. The polygon mirror 34 has a holding unit 38 extending radially outward from the cylindrical body 31.
It is mounted on the upper side in the axial direction, and is fixed from the outside in the axial direction by a pressing spring 39 serving as a clamping means.

A rotor flange portion 35 extends outward from the holding portion 38 in the radial direction. The rotor flange portion 35 includes the cylindrical body portion 31 and the holding portion 3.
8, and is arranged so as to separate a space inside the rotor where the drive coil 24 is arranged and a space outside the rotor where the polygon mirror 34 is arranged.

Further, a driving magnet 37 is provided on the inner peripheral wall surface of an annular mounting plate 36 projecting from the outer peripheral portion of the rotor flange portion 35 in the axial direction (downward in the figure) via a back yoke made of a magnetic material. It is mounted in a ring.
The drive magnet 37 is connected to the stator core 23 described above.
Is arranged so as to face the outer peripheral surface in the radial direction,
It constitutes a motor drive unit.

In the embodiment shown in FIG. 4, the holding portion 38,
Although the cylindrical body portion 31, the rotor flange portion 35, and the mounting portion 36 are integrally formed, each of them may be formed separately.

When a predetermined drive voltage is applied to the drive coil 24, the polygon mirror 34 and the cylindrical body 31 are moved together.
Is rotated, and the laser light converged on the polygon mirror 34 by the rotation of the polygon mirror 34 scans an image recording medium (not shown). At this time, the cylindrical body 31 is supported in the radial direction by the dynamic pressure of the air generated between the cylindrical body 31 and the fixed shaft 21, and the magnetic force between the rotating magnet 33 and the fixed magnet 27 is increased. Due to the suction action, the rotor set 30 is held in a state of floating by a predetermined amount in the thrust direction.

The fixed shaft 21 is made of an aluminum material such as aluminum or an aluminum alloy.
A lubricating film is formed on the outer peripheral surface including the dynamic pressure bearing surface by electrodeposition coating. The detailed structure of the fixed shaft 21 as such a shaft will be described together with a method of manufacturing the fixed shaft 21 according to one embodiment of the present invention.

In manufacturing the fixed shaft 21, FIG.
As shown in (1), first, the fixed shaft 21 is blanked (step 1). In the blank processing of the fixed shaft 21, a blank 21a as shown in FIG. 2 is formed by casting using aluminum, an aluminum alloy material, or a magnesium alloy, a die casting method, or another processing method. Next, the outer diameter of the blank 21a of the fixed shaft 21 is determined by finish lace processing (Step 2 in FIG. 1), and thereafter, the outer peripheral surface of the blank 21a is subjected to electrodeposition coating based on electrophoresis. . Prior to the electrodeposition coating, a film thickness adjustment surface 21b of the electrodeposition coating is formed on the edge of the step provided on the blank 21a. The film thickness adjusting surface 21b is for making the film thickness uniform at the time of electrodeposition coating. In the present embodiment, the film thickness adjusting surface 21b has an R curved surface shape having a curvature radius of 0.3 mm or more. The film thickness adjusting surface 21b is formed at least at the edge portion of the outer peripheral surface corresponding to the dynamic pressure surface and at the edge portion of the surface A corresponding to the mounting reference surface for the frame 10. The R-curved surface shape forming the surface 21b has a 0.5
The radius of curvature is set to be not less than mm.

When performing the electrodeposition coating, the outer surface of the blank 21a having the above-mentioned film thickness adjusting surface 21b is subjected to a chromate treatment (alodine treatment) or an alumite treatment for improving corrosion resistance and coating adhesion. A base treatment is performed. Next, the blank 21a is immersed in an electrodeposition tank (not shown), and the entire surface of the blank 21a is coated by electrodeposition (electric swimming) (step 3 in FIG. 1). In the electrodeposition coating, a blank 21a is put in a coating material dispersed in water, and the blank 21a is coated with the coating material by passing an electric current so that the blank 21a and the other metal body become both poles. .

As a resin material constituting the lubricating film formed by the electrodeposition coating, in addition to an anionic acrylic melamine resin, a cationic acrylic urethane, an epoxy urethane, an acryl-modified epoxy urethane resin, and the like, an electrophoretic resin. Any of them can be adopted. To these resins, a fluorinated powder such as PTFE is added to improve the slidability, or a carbon / graphite / metal powder is added to improve the conductivity, slidability and wear resistance. It is also possible to contain various coloring pigments.

The thickness of the electrodeposition lubricating film is adjusted and controlled by the time and voltage of electrodeposition.
In the present embodiment, the thickness is about 5 μm to 30 μm. When the film thickness is 5 μm or less, there is a problem in the abrasion resistance of the electrodeposition coating film. When the film thickness is 30 μm or more, defects such as “undulation” are generated on the electrodeposition coating surface. Because it occurs. After the electrodeposition coating, a heat treatment is performed to cure the resin, and a portion corresponding to the dynamic pressure bearing surface is subjected to a predetermined lubrication process.

After the electrodeposition coating step is completed, a dynamic pressure generating groove is formed on the surface on which the lubricating film is formed by excimer laser processing (step 4 in FIG. 1). This excimer laser is a gas laser using a rare gas halogen that forms a compound only in an excited state as a laser medium, and oscillates with ultraviolet light. Generally, a gas in which two gas elements such as fluorine (F) and argon (Ar) are sealed in a vacuum vessel is used, but the wavelength of the output laser differs depending on the gas to be combined. For example, a combination of Ar and Cl is 175 nm, a combination of Ar and F is 193 nm, and a combination of Kr and F is 2 nm.
49 nm, 282 mn in the case of Xe and Cl, and 353 mn in the case of Xe and F, and the finer the processing, the shorter the wavelength.

Examples of the excimer laser processing include a mask imaging method, a conformal method, a contact mask method, and the like. Any of the methods can be employed. The case where the contact mask method is used will be described. That is, as shown in FIG. 3, first, after the above-described electrodeposited blank 21 a is mounted on the support shaft 41 driven at a constant speed, the blank 21 a is brought close to the outer peripheral surface of the blank 21 a. The mask plate 42 is disposed substantially horizontally. In the mask plate 42, slit-shaped long holes 43 corresponding to the shape of the above-described dynamic pressure generating grooves 25 are formed in a plurality of rows so as to penetrate in a row. Laser light for processing is emitted from the laser head 44 arranged so as to face. This laser beam is configured to be transmitted through the slit-shaped elongated hole 43 and irradiated on the outer surface of the blank 21a.

At this time, it is desirable that the mask plate 42 is made to dissipate heat by using a material having good thermal conductivity so that the mask plate 42 is not fused to the blank 21a side by the processing heat. Further, the mask plate 42 may be disposed so as to directly contact the outer peripheral surface of the blank 21a, or may be disposed at an appropriate interval depending on the material of the electrodeposition coating film to reduce generated heat. It is also possible to adopt an arrangement relationship for efficiently dissipating.

Then, while the blank 21a is being rotated,
The mask plate 42 is irradiated with laser light while being reciprocated linearly in synchronization with the rotation.
Groove processing is performed on 1a. The irradiation area of the laser beam at this time is set to, for example, a range of 2 mm × 5 mm, and a processing depth per one shot is set to 0.3 μm. The processing is performed to a predetermined depth with high precision. In this case, processing ends at a frequency of 200 Hz in 3 to 10 seconds per piece.

By such excimer laser processing,
After the above-described groove 25 for generating dynamic pressure is formed in the fixed shaft 21, the ranking, that is, the assembly with the rotor set is performed, and the process is completed (Step 5 in FIG. 1).

According to this embodiment, a lubricating film can be easily obtained with a uniform thickness on the surface of the fixed shaft 21 by the uniform coating operation of the electrodeposition coating. Since the lubricating film formed of the electrodeposition coating portion is formed so as to have extremely good lubricity since lubricating particles float on the surface of the coating at the time of electrodeposition coating, the bearing characteristics are improved. Is achieved. Furthermore, in this electrodeposition coating, even if there is a defect such as a nest in the material of the coating partner, the coating enters the inside, so that the formed lubricating film has strong adhesion. . By using the fixed shaft 21 having the electrodeposition-coated lubricating film having good lubrication, the wear resistance on the hydrodynamic bearing surface is improved, and the generation of wear powder is greatly reduced. ,
The bearing gap is maintained and seizure is prevented.

In this embodiment, since the dynamic pressure generating grooves 25 are formed on the lubricating film formed by electrodeposition using excimer laser processing, burrs are generated as in conventional mechanical processing. High-precision grooving can be performed in a simple process without any problems. In particular, in the present embodiment, since the laser processing is performed using the mask plate 42, the groove processing is performed extremely efficiently.

At this time, if the depth of the groove processing by the excimer laser is set to be smaller than the film thickness of the electrodeposition lubricating film, the base of the blank 21a of the fixed shaft 21 will not be exposed after the groove processing. The underlayer treatment such as the alumite treatment for the blank 21a as in the above-described embodiment becomes unnecessary, and as a result, the productivity can be improved.

Further, as shown by reference numeral 44 'in FIG. 3, the optical axis of the excimer laser processing is
If it is arranged so as to form a predetermined angle θ with respect to the radial direction around the axis, and laser groove processing is performed, the wall surface forming the groove for generating dynamic pressure is It is formed to be inclined in the same direction. Therefore, according to the present embodiment, groove processing for inclining the groove wall in a direction suitable for generation of dynamic pressure is easily performed.

On the other hand, when the contact mask method is used, the thickness is desirably several μm to several tens μm. When importance is placed on the groove accuracy, it is preferable to use a mask that is as thin as possible. It is preferable to use a mask as thick as possible. When a chuck using a magnet is used during processing, it is desirable to use a magnetic metal.

Further, a defect (adhesion) due to heat generated by the absorption at the time of excimer laser irradiation,
Problems (reduction in mask accuracy) due to reattachment of the decomposition gas may cause a problem. In this case, it is desirable to employ a mask imaging method. For example, a predetermined pattern is formed by condensing a laser beam having passed through an enlargement mask having a magnification of 2 to 14 times by a lens and projecting the laser beam on a blank of the fixed shaft 21 as a workpiece.

The embodiment of the invention made by the inventor has been specifically described above. However, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist of the invention. Needless to say.

For example, not only when the dynamic pressure generating groove is provided on the shaft body (fixed shaft 21) side but also on the shaft fitting body (cylindrical body 31) side as in the above embodiments. However, the present invention can be similarly applied. That is, the present invention can be similarly applied to a case where electrodeposition coating is performed on the shaft fitting body side or a case where electrodeposition coating is performed on both the shaft body and the shaft fitting body.

Further, each of the above-described embodiments is a case of a hydrodynamic bearing device using air as a lubricating fluid, but the present invention can be similarly applied to a device using a liquid such as oil. it can.

Further, the present invention is similarly applied to a dynamic pressure bearing device used in a device other than the above-described motor, for example, a dynamic pressure bearing device provided in a hard disk drive (HDD) motor. be able to.

[0050]

As described above, according to the first aspect of the present invention, a lubricating film is formed by electrodeposition coating on at least one of the surfaces of the dynamic pressure bearings of the shaft body and the shaft fitting body. Since the grooves for dynamic pressure generation are formed by excimer laser processing on the coating film, the uniform coating action of electrodeposition coating makes it possible to easily obtain a lubricating film with a uniform thickness over the entire circumference. In addition, the groove processing can be performed with high accuracy by a simple process without generating burrs unlike the conventional machining. Therefore, productivity can be improved while improving the performance of the dynamic pressure bearing device.

In the second aspect of the present invention, the groove processing depth by the excimer laser processing is set to be smaller than the film thickness of the electrodeposition-coated lubricating film, so that the underlayer treatment is not required. The effect can be further enhanced.

Further, in the third aspect of the present invention, since the groove processing is performed very efficiently by performing excimer laser processing using a masking member, the above-described effect can be further enhanced. .

Further, in the invention according to claim 4, the excimer laser processing is performed in an oblique direction so that the grooves are inclined in a direction suitable for generation of dynamic pressure, so that the processing is excellent. Groove processing with dynamic pressure characteristics can be performed extremely efficiently, and the above-described effects can be further enhanced.

[Brief description of the drawings]

FIG. 1 is a process explanatory view showing a method for manufacturing a shaft according to an embodiment of the present invention.

FIG. 2 is an explanatory side view showing a blank of a shaft body.

FIG. 3 is a perspective explanatory view showing a principle structure of an apparatus for carrying out the present invention.

FIG. 4 is a cross-sectional explanatory view showing an example of a fixed-shaft type polygon mirror driving motor provided with a dynamic pressure bearing to which the present invention is applied.

FIG. 5 is an explanatory view showing a manufacturing process of a conventional shaft fitting body.

FIG. 6 is an explanatory view showing a conventional shaft manufacturing process.

[Explanation of symbols]

 21 Fixed shaft (shaft) 25 Groove for generating dynamic pressure 31 Cylindrical body (shaft fitting) 21a Fixed shaft blank 21b, 21c Film thickness adjusting surface 42 Mask plate 44 Laser head

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yoshitaka Murayama 5329 Shimosuwa-cho, Suwa-gun, Nagano Prefecture F-term in Sankyo Seiki Seisakusho Co., Ltd.

Claims (4)

[Claims] At least one pair of radially opposed hydrodynamic bearing surfaces is formed by an outer peripheral surface of a shaft body and an inner peripheral surface of a shaft fitting body rotatably mounted on the shaft body. And a method of manufacturing a dynamic pressure bearing device in which a dynamic pressure generating groove having a predetermined shape is formed in one of the two dynamic pressure bearing surfaces of the shaft body and the shaft fitting body. Forming a lubricating film on at least one surface of the combined hydrodynamic bearing surfaces by electrodeposition coating; and forming the lubricating film by excimer laser processing on the surface on which the lubricating film is formed by electrodeposition coating. Forming a hydrodynamic bearing device. 2. A method for manufacturing a hydrodynamic bearing device, wherein a processing depth of a groove formed by the excimer laser processing step according to claim 1 is set to be smaller than a film thickness of an electrodeposition coating lubricating film. 3. The excimer laser processing step according to claim 1, wherein the lubricating film is covered by a masking member having a predetermined shape in which a hole having a shape corresponding to the dynamic pressure generating groove is formed. Manufacturing method of a dynamic bearing device. 4. The excimer laser processing step according to claim 1, wherein an optical axis of the laser beam for performing the excimer laser processing is at a predetermined angle with respect to a radial direction of the shaft body or the shaft fitting body as a workpiece. A method for manufacturing a hydrodynamic bearing device, characterized in that: