JP2001311424A - Manufacturing method of liquid bearing components, motor provided with fluid bearing components, and disk drive using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method that enables manufacturing a fluid bearing components in which no excessive wear results after long period of operation and offering an excellent productivity. SOLUTION: After forming a metal layer composed of metallic material having a hardness higher than that of copper over the surface of base material of which chief constituent is the copper, dynamic pressure grooves are built on the metal layer by an electrochemical machining. In view of the hardness of the metal layer and the electrochemical machinability, a metal layer had better be a nickel as a main constituent. A metal layer also had better be formed by a plating, because of an uniform metal layer obtained. In order to improve further the abrasion resistance property by increasing the hardness of the metal layer, it is better that an annealing treatment is applied after the metal layer is formed by an electroless nickel plating. The layer thickness of the metal layer is preferable to be in the range of 5-30 μm, due to a tradeoff between the depth of dynamic pressure grooves and the uniformity of the layer thickness of the formed metal layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a hydrodynamic bearing component, and more particularly, to a method of manufacturing a hydrodynamic bearing component which does not wear out even when used for a long period of time and which exhibits excellent productivity. Things.

[0002]

2. Description of the Related Art Copper-based materials have been widely used as materials for hydrodynamic bearing parts because of their excellent workability and low cost. However, as an opposite effect of the excellent workability of the material containing copper as a main component, there is a problem that the material is easily worn by use. Therefore, it has been conventionally proposed and studied to use a hard bearing material plated on the surface of a fluid bearing component made of the material.

[0003]

However, when a hard material is plated after forming a dynamic pressure groove on the surface of the fluid bearing part by cutting, fine burrs, chips, or chips generated by cutting are removed. Because it remains around the groove,
Plating is performed using these as nuclei, and fine projections are generated on the plating surface. These protrusions may cause abnormal rotation of the motor, and when peeled off from the plating layer, may become foreign matters, damaging the shaft body and the sleeve, and hindering the operation of the motor.

[0004] In order to remove fine burrs, scraps or chips, it is conceivable to wash the groove portion after cutting the dynamic pressure groove. However, cleaning cannot remove these grooves completely. As another method, the surface may be polished, but it is technically difficult to polish a groove having a depth of about several tens of μm. In addition, either method requires a new process in the production process, which complicates the production process and lowers productivity. Further, when the dynamic pressure groove is processed by electrolytic processing, burrs, peeling, and chips are not generated, but cannot be used for a material mainly composed of copper having a small ionization tendency.

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and it is possible to manufacture a hydrodynamic bearing part which forms a required dynamic pressure groove accurately and does not wear out even after long-term use. It is an object of the present invention to provide a production method showing high productivity. It is another object of the present invention to provide a motor and a disk drive using the hydrodynamic bearing component manufactured by the manufacturing method.

[0006]

In order to achieve the above object, in the method of manufacturing a hydrodynamic bearing component according to the present invention, a metal layer made of a metal material having a higher hardness than copper is formed on a surface of a base material containing copper as a main component. Is formed, and a dynamic pressure groove is formed in the metal layer by electrolytic processing.

Here, from the viewpoint of the hardness of the metal layer and the electrolytic workability, it is preferable that the metal layer is mainly composed of nickel. It is recommended that the metal layer be formed by plating, since a uniform metal layer can be obtained. Further, from the viewpoint of further increasing the hardness of the metal layer to further improve the wear resistance, it is desirable to perform the annealing after forming the metal layer by electroless nickel plating. The thickness of the metal layer is preferably in the range of 5 to 30 μm in consideration of the depth of the dynamic pressure groove and the uniformity of the thickness of the metal layer to be formed.

Further, the motor of the present invention has a sleeve member, a shaft member rotatable relative to the sleeve member, and a lubricating fluid filled between the sleeve member and the shaft member. A motor provided with a fluid dynamic bearing, wherein at least one of the sleeve member and the shaft member is a fluid bearing component manufactured by the above-described manufacturing method.

Further, according to the disk device of the present invention, in a disk device on which a disk-shaped recording medium capable of recording information is mounted, a housing, a spindle motor fixed inside the housing, and an information storage device at a required position of the recording medium. A disk device provided with information access means for writing and / or reading data, wherein the motor described above is used as the spindle motor.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have made intensive studies on whether or not a hydrodynamic bearing part which does not wear out even after long-term use can be manufactured and a manufacturing method showing excellent productivity can be provided. The present inventors have found that a metal layer having a high hardness may be formed on the surface of a base material, and then a dynamic pressure groove may be formed by electrolytic processing.

That is, one of the major features of the manufacturing method of the present invention is that a dynamic pressure groove is formed after a metal layer made of a metal material having a higher hardness than copper is formed on the surface of a base material mainly composed of copper. On the point. Conventionally, a dynamic pressure groove was first formed on the base material, and then plating was performed, so that fine burrs generated when the dynamic pressure groove was formed, plating or even chips were made, Although fine projections having these as nuclei were formed in the plating layer, in the manufacturing method of the present invention, since the dynamic pressure grooves are formed after forming the metal layer, the conventional problems do not occur. In addition, since a metal layer made of a metal material having a high hardness is formed on the surface of the base material, the metal layer does not wear even after long-term use.

Here, the base material containing copper as a main component basically means a base material containing 50 wt% or more of copper. Specifically, in addition to pure Cu, Cu—Zn (brass), Cu— Ni,
Cu-Sn (bronze), Cu-Si, Cu-Al, Cu-
Be, Cu-Zn-Mn, Cu-Zn-Si, Cu-Z
n-Ni, Cu-Sn-P, Cu-Sn-Zn, Cu-
Examples include Zn-Sn-Fe and Cu-Zn-Sn-Mn, but are not limited to these.

As a metal material having a higher hardness than copper,
There is no particular limitation as long as it has higher hardness than copper and can be electrolytically processed. For example, Ni, Fe, Cr, Co, Mo,
Examples include metal elements such as Ti and W and alloys containing these as main components. Among them, a metal material mainly composed of Ni can be preferably used from the viewpoint of electrolytic workability and metal hardness. As a metal material mainly composed of Ni, pure Ni
Besides, Fe, Al, Ti, Nb, Co, Cr, Mo,
An alloy of one or more elements selected from the group consisting of W, V, Ta, Si, C, B, Zr, and P with Ni is exemplified.

As a method for forming a metal layer on the surface of a substrate, there are plating methods such as electroplating, electroless plating and hot-dip plating; physical vapor deposition such as vacuum deposition and sputtering (PV).
D) method; thermal chemical vapor deposition (CVD), plasma CVD, light C
A CVD method such as VD can be used. These methods are briefly described below.

In the electroplating method, a substrate is immersed in an aqueous solution containing metal ions constituting a metal layer, and this is used as a cathode. On the other hand, a suitable soluble or insoluble anode is provided. In this method, a direct current is passed between a cathode and an anode to electrolytically deposit a target metal layer on the surface of a base material. Electrolytic conditions such as electrolysis time, current density, electrolysis temperature, current waveform, current density distribution, stirring conditions, etc .; metal ion concentration and ratio, type and concentration of additives, impurities in aqueous solution It can be controlled by the composition of the aqueous solution such as the amount. Before performing electroplating, it is recommended to perform polishing to adjust the surface roughness of the substrate, pickling to clean the surface, and degreasing, and after performing electroplating,
It is recommended to perform a heat treatment for removing hydrogen embrittlement in addition to washing and drying.

In the electroless plating method, a material to be plated is immersed in a solution in which ions of a metal to be plated and a reducing agent are present, and electrons are released by oxidation of the reducing agent. Is a method in which the electrons are reduced to deposit a metal on the material to be plated. Details will be described later.

The hot-dip plating method is a method in which a substrate is immersed in a molten metal having a low melting point to form a metal layer having high adhesion on the surface of the substrate. The formed plating layer is composed of an alloy layer formed by a reaction between a solid / liquid phase of a base material and a molten metal in a molten metal bath, and a metal layer of a bath composition which is pulled up from the bath together with the base material and adhered and solidified. It is composed of

The vacuum deposition method is a method in which a metal material is heated in a vacuum, and the generated vapor is condensed and adhered on a substrate to form a metal layer. Examples of the method for heating the deposition material include resistance heating, a heating crucible, an electron beam, high frequency, and laser. When an alloy layer such as Fe-Ni or Al-Cu is formed by this method, the composition may be different between the vapor deposition material and the formed metal layer. In this case, a binary vapor deposition method in which vapor deposition materials are separately used may be used.

In the sputtering method, particles having high energy are made to collide with a solid to strike out atoms and molecules on the solid surface from the solid surface, and to scatter the atoms and molecules scattered on a substrate placed near the solid. This is a method of forming a layer. Sputtering methods include DC bipolar sputtering, magnetron sputtering, facing target sputtering, ion beam sputtering, ECR
Although there are types such as sputtering, any method may be used for forming the metal layer of the present invention.

The thermal CVD method is a method in which a raw material gas is heated to a high temperature and thermally activated to promote a chemical reaction, thereby forming a metal layer on a substrate. Plasma CVD is a method in which a reactive gas is excited by plasma to generate active ions and radicals to form a metal layer on a substrate. Compared to thermal CVD, which requires high temperatures, this method has a wider range of applicable substrates. The photo-CVD method is a method of irradiating photon energy to a CVD reaction field to excite or activate a reactive chemical species to form a metal layer.

Among the above-described methods for forming a metal layer,
When a metal layer made of a metal material mainly composed of Ni is formed on the surface of the base material, it is recommended to use an electroless plating method capable of performing uniform plating. At this time, it is desirable to use sodium hypophosphite or borohydride as the reducing agent.

When sodium hypophosphite is used as a reducing agent, nickel chloride or sulfate is used as a metal salt, and Ni precipitates autocatalytically through a complicated reaction. Phosphorus is contained in the precipitate, and an Ni-P alloy is generated. A plating layer having high hardness (about Hv500) can be obtained by such eutectoid of phosphorus. By performing an annealing treatment as described later, the hardness can be further increased, and can be increased to a maximum of about Hv800. The hardness of the fluid bearing component is preferably Hv400 or more, and more preferably Hv600 or more.

On the other hand, when borohydride is used as a reducing agent, specifically, when amine borane or sodium borohydride is used, both Ni-B alloys precipitate. When amine borane is used as the reducing agent, the purity of nickel is increased and a metal layer having high hardness is obtained (Hv8
00). When sodium borohydride is used as the reducing agent, an alloy having a higher borane content than that using amine borane can be obtained. The hardness of this alloy can be increased by annealing. Further, since this alloy has a high melting point and maintains high hardness even at high temperatures, it is suitable as a metal layer formed on the base material surface of a fluid bearing component.

The thickness of the metal layer formed on the surface of the substrate is preferably in the range of 5 to 30 μm. Metal layer thickness is 5
If it is less than μm, it may not be possible to form a hydrodynamic groove having a sufficient depth, while if it is more than 30 μm,
This is because the thickness of the metal layer may be non-uniform.
A more preferred lower limit of the thickness of the metal layer is 10 μm,
A more preferred upper limit is 20 μm.

In order to further increase the hardness of the metal layer formed on the surface of the base material, it is preferable to perform annealing after forming the metal layer. The specific conditions of the annealing treatment may be appropriately determined from the composition and the thickness of the metal layer. Preferably 200-4
The range is 0.5 to 4 hours at 00 ° C. The annealing may be performed before or after the formation of the dynamic pressure grooves.

Another major feature of the manufacturing method according to the present invention is that a dynamic pressure groove is formed in the metal layer by electrolytic processing. In the cutting process conventionally used exclusively as a method of forming the dynamic pressure groove, fine burrs, dings or chips are inevitably generated, and the above-described problem has occurred. Thus, the conventional problems caused by these are completely solved.

The electrolytic processing used in the present invention refers to a processing method for obtaining a required shape, size and surface state by concentrating and restricting an electrochemical dissolving action to a required portion of a material. FIG. 1 shows a general configuration of electrolytic processing. FIG. 1 is a diagram showing an overall configuration of an electrolytic processing apparatus for forming a radial dynamic pressure groove in a hollow cylindrical workpiece 16 used as a support member of a spindle motor. Hollow cylindrical workpiece 16
Is fixed in the processing chamber 42, and a columnar tool electrode 44 is attached to the processing apparatus housing 40 such that the exposed electrode 44 a faces the inner peripheral surface of the workpiece 16 with a small gap. Here, the exposed electrode 44a has a shape similar to the shape of the radial dynamic pressure groove to be formed on the workpiece (the herringbone shape in FIG. 1), and has a width slightly smaller than the radial dynamic pressure groove. Have been.

A positive electrode terminal 60 extending from a positive power supply terminal of the processing power supply 54 is connected to the workpiece 16, and a current flowing between the workpiece 16 and the tool electrode 44 is provided in the middle of the positive terminal 60. A current detecting means 58 for detecting is provided.
On the other hand, a negative electrode terminal 62 extending from a negative power supply terminal of the processing power supply 54 is connected to the tool electrode 44, and in the middle thereof, a DC voltage (pulse voltage) from the processing power supply 54 is turned on / off. A switch means 46 for performing the operation is provided.

On the other hand, the electrolytic solution is stored in the electrolytic solution tank 50, and the electrolytic solution tank 50 and the supply port of the processing chamber 42 are connected by a supply pipe via a circulation pump 48, and the processing chamber 4
The discharge port 2 and the electrolyte tank 50 are connected by a discharge pipe. At the time of electrolytic processing, the circulation pump 48 is operated,
The electrolytic solution 52 is supplied from the electrolytic solution tank 50 to the processing chamber 42. The electrolytic solution 52 supplied to the processing chamber 42
2 flows through the gap between the workpiece 16 and the tool electrode 44 from the upper part of 2 and reaches the lower part of the processing chamber 42. And the electrolyte 52 is
From the lower part of the processing chamber 42 through the discharge pipe, the electrolyte tank 50
And is supplied to the processing chamber 42 by the circulation pump 48. Here, the workpiece 16
When passing through the gap between the tool electrode 44 and the tool electrode 44, the electrolytic product is mixed into the electrolytic solution. In electrolytic processing, the current density is extremely large and the processing gap is extremely small, so the generation of electrolytic products and the heating of the electrolytic solution have a large effect on the processing, and the processing will not proceed unless these effects are removed immediately. There is a risk. Therefore, the flow rate of the electrolytic solution needs to be high, and although it depends on the processing conditions, it is generally desirable to be in the range of 6 to 60 m / sec. When the electrolytic product is a precipitate, the electrolytic solution tank 50 is subjected to centrifugation, sedimentation, filtration, and a combination thereof.
It is preferable to separate and remove the electrolytic product from the electrolytic solution therein and to clean the electrolytic solution before circulating it.

In the apparatus having such a structure, when the switch means 46 is turned on for a predetermined time (machining time), a DC voltage (pulse voltage) is applied between the workpiece 16 and the tool electrode 44, and A current flows from the processing power supply 54 between the tool electrode 16 and the tool electrode 44. And for example NaCl
When the liquid is a charge liquid and the surface of the workpiece is Ni, the following electrode reactions mainly occur.

Work surface: Ni → Ni ²⁺ + 2e ⁻ Tool electrode surface: 2Na ⁺ + 2H ₂ O + 2e ⁻ → 2NaOH
+ H ₂

Due to such a reaction, the surface material of the workpiece 16 facing the exposed electrode of the tool electrode 44 elutes into the electrolytic solution 52, and a dynamic pressure groove having a shape corresponding to the exposed electrode is formed. Formed on the surface.

At the time of machining, a current flowing between the workpiece 16 and the tool electrode 44 is detected by a current detecting means 58, and the detected value is sent to an energization control circuit 56, where a switch means 46 is provided based on the detected value. Is turned on and off.
As a result, groove processing of stable quality can be always performed without being affected by the amount of the electrolytic product eluted into the electrolytic solution 52, the flow rate of the electrolytic solution at the processing position, and other various processing conditions.

The processing conditions for the electrolytic processing may be determined as appropriate from the composition and shape of the workpiece and the depth, width and shape of the groove to be formed. As an example of the processing conditions, a processing voltage of 10 V, a processing current of 10 A, a processing time (time for turning on the switch means 46) of 3 seconds, a gap between the processing surface of the workpiece 16 and the electrode surface of the tool electrode 44 are set to 0. When it is set to 1 mm, a dynamic pressure groove having a desired shape with a depth of 10 μm can be formed.

Next, the motor of claim 6 will be described.
The motor according to claim 6 is a motor provided with a fluid dynamic pressure bearing, wherein at least one of the sleeve member and the bearing member, which are parts of the fluid dynamic pressure bearing, is manufactured by the manufacturing method described above. This is a major feature. With such a configuration, the motor of the present invention can maintain high-speed and stable rotation for a long time.

Hereinafter, the motor of the present invention will be described in detail with reference to the drawings. FIG. 2 is a schematic sectional view of a fluid bearing motor for driving a recording disk, which is an embodiment of the motor of the present invention. The motor 1 includes a bracket 2, a shaft 4 whose one end is externally fixed to a central opening of the bracket 2, and a rotor 6 rotatably held relative to the shaft 4. A stator 12 is fixed to the bracket 2, and a rotor magnet 10 is provided on the rotor 6 at a position facing the stator 12.
A rotational driving force is generated between the motor and the rotor magnet 10.

A disk-shaped upper thrust plate 4a and a lower thrust plate 4b projecting radially outward are provided on the upper and lower portions of the shaft 4, and a gas intervening portion 22 is provided on the outer surface of the shaft between these thrust plates. Is formed.

On the other hand, the rotor 6 is supported on the shaft 4 via a rotor hub 6a on the outer periphery of which a recording disk D is mounted and an inner periphery of the rotor 6 via a minute gap in which the lubricating oil 8 is held. And a sleeve 6b. Further, the sleeve 6b is provided with an upper counter plate 7a and a lower counter plate 7b so as to cover the outer sides of the upper and lower thrust plates.

Here, the shaft 4 and the upper and lower thrust plates 4a and 4b correspond to the shaft member of the present invention, and the sleeve 6b corresponds to the sleeve member of the present invention. Both or either one of the shaft member and the sleeve member is obtained by forming a plating layer mainly composed of nickel on the surface of a base material mainly composed of copper. As described later, a herringbone-shaped dynamic pressure groove 24 is formed on the upper and lower inner surfaces of the inner peripheral portion through hole 6c of the sleeve 6b, and a spiral dynamic pressure groove is formed on the lower surface of the upper thrust plate 4a and the upper surface of the lower thrust plate 4b. The pressure grooves 14 are respectively formed by electrolytic processing.

An opposing sleeve 6b extends from the outer peripheral portion of the shaft 4 adjacent to the upper portion of the gas intervening portion 22 provided at the central portion of the shaft 4 to the lower surface, the outer peripheral surface and the outer peripheral portion of the upper thrust plate. Inner peripheral through hole 6c
A small gap is formed between the upper part of the upper counter plate 7a and the lower part of the upper counter plate 7a, and the lubricating oil 8 is held. On the lower surface of the upper thrust plate 4a and on the upper surface of the lower thrust plate 4b, a spiral dynamic pressure groove 14 for generating a dynamic pressure in the lubricating oil 8 with the rotation of the rotor 6 is formed. The dynamic pressure groove 14 has a function of generating a supporting force for holding the rotor portion in the axial direction when the motor rotates, and at the same time, has an effect of pushing the lubricating oil 8 back in the direction of arrow A. Further, a herringbone-shaped dynamic pressure groove 24 is formed in the lubricating oil holding portion on the upper and lower inner surfaces of the inner peripheral portion through hole 6c of the sleeve 6b. The dynamic pressure groove 24 has a function of generating a supporting force for holding the rotor portion in the radial direction when the motor rotates, and at the same time, has an effect of pushing up the lubricating oil 8 in the direction of arrow B.

The dynamic pressure distribution of the lubricating oil 8 in the minute gap generated by these dynamic pressure grooves is highest at the lower surface inner peripheral portion P of the upper thrust plate. As a result, when the air dissolved in the lubricating oil 8 becomes bubbles, the bubbles are diffused and eliminated to the outside of the inner peripheral portion P, and the lower gas interposition portion 22 or the upper counter plate 7a lower surface gap is formed. Leads to. These gaps are directly or externally open air communication holes 2.
Since the air is released to the atmosphere by 0, the air bubbles are released to the outside air from here, and the leakage of the lubricating oil due to the expansion of the air bubbles is prevented.

Further, a taper seal portion is formed between the lower surface of the counter plate 7a, which is the end of the lubricating oil holding portion, and the upper surface of the upper thrust plate 4a. The lubricating agent is applied to the end of the seal portion. Similarly, the gas intervening portion 22 at the center of the shaft 4, which is the other end of the lubricating oil holding portion,
A taper seal portion is formed between the outer peripheral surface of the shaft 4 and the inner peripheral surface of the sleeve 6b, and the gap gradually increases as the distance from the lubricating oil holding portion to the lower side in the axial direction increases. An lubricating agent is applied to the end. The lubricating oil is held at a position where the dynamic pressure, the atmospheric pressure, and the surface tension of the tapered seal portion generated inside the lubricating oil are balanced by the tapered seal portions formed at both ends. The lubricating agent applied to the tapered seal portion also has a function of preventing so-called oil migration, in which lubricating oil diffuses along the metal surface of the shaft or sleeve. With these lubricating oil holding structures, a fluid bearing structure with no leakage of lubricating oil and high load supporting force is realized.

A similar structure of the minute gap, the dynamic pressure groove, and the lubricating oil holding portion is provided by the gas intervening portion 2 provided at the center of the shaft 4.
2, the lower thrust plate 4b and the lower counter plate 7b are formed upside down so that the rotor portion is more stably supported by the lower dynamic pressure bearing portion.

The hydrodynamic bearing motor having such a structure is
The upper and lower counter plates 7a and 7b effectively prevent the lubricating oil 8 from escaping outward due to the rotational centrifugal force even at a high speed of about 20,000 revolutions per minute, thereby realizing even higher speed and stable rotation. can do.

Next, a disk device according to a seventh aspect will be described. This disk device writes and / or writes information on a recording medium mounted on a rotating section of a spindle motor.
Alternatively, an apparatus for performing reading by an information access means, wherein the motor according to claim 6 is used as the spindle motor.

FIG. 3 is a schematic explanatory view showing one embodiment of the disk drive of the present invention. Inside a housing 71, a spindle motor 72 rotatably supporting a disk plate (recording medium) 73 for storing various information in a digital format at high density, and information access means for reading and writing information from and to the disk plate 73 77 are arranged. The information access means 77 includes a head 76 for reading and writing information on the disk plate 73, and an arm 75 for supporting the head 76.
And an actuator unit 74 for moving the head 76 and the arm 75 to required positions on the disk plate 73. The motor of claim 6 is used as the spindle motor 72.

Incidentally, the information density that can be stored on the disk plate has been dramatically improved in recent years, and dust and
A clean environment with extremely little dust is essential. Therefore, in order to make the inside of the housing 71 a highly clean space insulated from the outside air, the information access means 77 and the spindle motor 72, which are the internal components thereof, use the mist of the lubricating oil used therein. It is desirable to use a mechanism that does not leak to the outside.

[0048]

According to the first aspect of the present invention, a metal layer made of a metal material having a higher hardness than copper is formed on the surface of a base material containing copper as a main component, and then the metal layer is subjected to a hydrodynamic pressure by electrolytic processing. Since the grooves are formed, it is not necessary to remove protrusions of the metal layer caused by burrs, chips and chips, and it is possible to manufacture a hydrodynamic bearing part which does not wear out even after long-term use. Is improved. If the metal layer is mainly made of nickel, a metal layer excellent in balance between hardness and electrolytic workability can be obtained. Further, by forming the metal layer by plating, a uniform metal layer can be obtained. Further, by performing annealing after forming the metal layer by electroless nickel plating, the hardness of the metal layer can be further increased and the wear resistance can be further improved. When the thickness of the metal layer is in the range of 5 to 30 μm, the balance between the depth of the formed dynamic pressure groove and the uniformity of the thickness of the formed metal layer can be maintained.

In the motor according to the present invention, the fluid dynamic pressure bearing is provided, and at least one of the sleeve member and the shaft member of the fluid dynamic pressure bearing is manufactured by the manufacturing method of the present invention. And stable rotation at high speed can be realized.

In the disk drive of the present invention, a spindle motor fixed to the inside of the housing and having a recording medium mounted on a rotating section is provided, and the motor of the present invention is used as the spindle motor, so that the life of the drive is extended. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of electrolytic processing used in the manufacturing method of claim 1.

FIG. 2 is a schematic configuration diagram of a motor according to claim 6;

FIG. 3 is a schematic configuration diagram of a disk device according to claim 7;

[Explanation of symbols]

 Reference Signs List 1 motor 4 shaft 6b sleeve (sleeve member) 8 lubricating oil (lubricating fluid) 14, 24 dynamic pressure groove 16 workpiece 44 tool electrode 44a exposed electrode 71 housing 72 spindle motor 73 disk plate (recording medium) 77 information access means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J011 AA20 BA02 BA06 CA02 CA05 DA02 JA02 KA02 KA03 MA02 QA03 RA03 SB03 SB15 5H607 BB01 BB17 CC01 CC05 DD05 DD16 FF01 GG01 GG02 GG12 GG15 KK10

Claims (7)

[Claims] 1. A method according to claim 1, wherein a metal layer made of a metal material having a higher hardness than copper is formed on the surface of the base material containing copper as a main component, and then a dynamic pressure groove is formed in the metal layer by electrolytic processing. Manufacturing method of hydrodynamic bearing parts. 2. The method according to claim 1, wherein the metal layer is mainly made of nickel. 3. The method according to claim 1, wherein the metal layer is formed by plating. 4. The method according to claim 3, wherein the annealing is performed after the metal layer is formed by electroless nickel plating. 5. The method according to claim 1, wherein the thickness of the metal layer is in a range of 5 to 30 μm. 6. A fluid dynamic bearing comprising a sleeve member, a shaft member rotatable relative to the sleeve member, and a lubricating fluid filled between the sleeve member and the shaft member. A motor comprising: a motor, wherein at least one of the sleeve member and the shaft member is a fluid bearing component manufactured by the manufacturing method according to claim 1. 7. A disk drive on which a disc-shaped recording medium capable of recording information is mounted, a housing, a spindle motor fixed inside the housing, and writing and / or reading of information at a required position of the recording medium. 7. A disk device comprising: an information access unit for: a disk drive, wherein the motor according to claim 6 is used as the spindle motor.