JP2002079425A - Hydrodynamic groove machining device for hydrodynamic bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrodynamic groove machining device of a hydrodynamic bearing capable of using an electrode tool for a long period in comparison with a conventional one in forming a hydrodynamic groove by electrochemical machining. SOLUTION: As the electrode tool 1 having a structure formed by coating a part excluding a conductive part 13, of a surface of a metallic base 11 with a resin layer 12 by attaching and baking resin fine particles, to expose the conductive part 13 corresponding to a pattern of the hydrodynamic groove, is used for machining the hydrodynamic groove on a surface of a workpiece W, the adhesive strength to the base 11 can be improved, and the life of the electrode tool 1 depending on the separation of the non-conductive material can be remarkably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure groove machining apparatus for machining a dynamic pressure groove of a dynamic pressure bearing based on an electrolytic machining method.

[0002]

2. Description of the Related Art In recent years, a dynamic pressure bearing device has been widely used as a bearing device used for a mechanism requiring high-speed and high-precision rotation such as a hard disk device. In general, a hydrodynamic bearing injects a working fluid between a shaft and a bearing, forms a hydrodynamic groove in one of the shaft and the bearing, and pumps the working fluid by a pumping action or the like generated by relative rotation between the shaft and the bearing. The pressure is increased, and the dynamic pressure supports the shaft so that it can rotate relative to the bearing.

The dynamic pressure grooves are formed, for example, in a spiral pattern, V
A pattern, a herringbone pattern, or the like is frequently used, and in order to achieve a groove with a high precision of about ± 0.5 μm, electrolytic processing has been mainly used conventionally.

That is, when forming such a dynamic pressure groove, a workpiece made of a conductive material and an electrode tool having a conductive portion of the dynamic pressure groove pattern exposed on the surface are opposed to each other in an electrolytic solution. Immersion, and during this time, the electrolyte is allowed to flow. Then, the workpiece is connected to the positive electrode and the electrode tool is connected to the negative electrode, and by energizing, the portion of the workpiece facing the conductive part pattern is eluted from the workpiece surface, and the movement corresponding to the pattern is performed. Form pressure grooves.

[0005] As an electrode tool used for electrolytic machining of such a dynamic pressure groove, generally, a region excluding the pattern is hidden on the surface of a metal base so that a metal portion is exposed by the dynamic pressure groove pattern. A structure coated with a non-conductive material is used as much as possible. Conventionally, the coating with a non-conductive material is performed by forming a uniform resist film on the surface of the substrate and then removing unnecessary portions using a photolithography technique, or forming a dynamic pressure groove pattern on the surface of the substrate. A region in which a region to be removed is removed by etching or the like and a synthetic resin is embedded in the recess is used.

[0006]

By the way, in the above-mentioned conventional electrode tools for processing a dynamic pressure groove, as a non-conductive material, a resist film is formed on the surface of a substrate,
Alternatively, since a material only having a synthetic resin embedded therein is used, there is a problem that the service life cannot be prolonged due to weak adhesion between the non-conductive material and the substrate and easy peeling.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and in forming a dynamic pressure groove by electrolytic processing, a dynamic pressure bearing in which the electrode tool can be used for a longer time than before. The purpose is to provide a dynamic pressure groove machining device.

[0008]

According to a first aspect of the present invention, there is provided a dynamic pressure groove machining apparatus for a dynamic pressure bearing, comprising: a workpiece on which a dynamic pressure groove is to be formed; The electrode tool with the conductive part of the pattern exposed on the surface is immersed in the electrolytic solution so as to be opposed to the electrode tool. In the dynamic pressure groove processing apparatus for forming a dynamic pressure groove having a shape corresponding to the exposed pattern of the conductive portion of the electrode tool on the surface of the workpiece by flowing the liquid, the electrode tool is used to clean the surface of the metal base. It is characterized by having a structure in which a region other than the above-mentioned predetermined pattern is covered with a resin layer formed by attaching and baking resin fine particles.

In order to achieve the same object, in the dynamic pressure groove machining apparatus for a dynamic pressure bearing according to the second aspect of the present invention, a hole of a dynamic pressure groove pattern to be machined is formed on a surface of a metal base as an electrode tool. Are formed in advance and a structure in which a resin sheet is fixed is used.

The present invention improves the adhesion of a non-conductive material covering an unnecessary area on the surface of a metal substrate to expose a conductive portion of the dynamic pressure groove pattern on the surface of the substrate. In the invention according to claim 1,
By using a resin layer formed by adhering resin particles to the surface of the substrate and baking it as a non-conductive material, the adhesion to the substrate can be greatly improved as compared with the conventional resist film formation and resin embedding. it can. Here, in the invention according to the first aspect, a method of baking the resin fine particles on the substrate surface in a slurry state and spraying the slurry on a required pattern, and a method of baking the resin particles over the entire surface of the substrate and then using a laser or the like, Any of the methods of patterning into a required shape by removing a portion can be adopted. Further, as a material of the resin fine particles, a polyimide resin or the like having a high insulating property can be suitably used.

On the other hand, in the invention according to claim 2, an electrode tool having a structure in which a resin sheet patterned in a required shape in advance is fixed to the surface of a metal base with an adhesive or the like is used. Also in the electrode tool, the adhesion of the non-conductive material to the substrate can be greatly improved compared to the conventional electrode tool in which a non-conductive material is attached by forming a conventional resist film or embedding a resin. .

According to the second aspect of the present invention,
Since the pre-patterned resin sheet is attached to the base, there is also an advantage that the base itself can be reused even if the attachment fails, and that the manufacturing process of the electrode tool can be simplified.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing the overall configuration of a dynamic pressure groove machining apparatus for a dynamic pressure bearing according to the present invention.
Is a longitudinal sectional view of the electrode tool 1. FIG.

The workpiece W is placed in the processing tank 2 with the electrode tool 1 facing the surface on which the dynamic pressure groove is to be formed. In the processing tank 2, pipes 4a and 4b communicating with the electrolyte tank 3 are provided.
The electrolytic solution flows between the workpiece W and the electrode tool 1 by driving the pump 5.

The positive electrode of the machining power source 6 is connected to the workpiece W, while the negative electrode of the machining power source 6 is connected to the electrode tool 1. For example, a pulse-shaped current is flowed while the electrolyte is flowing.

On the surface of the electrode tool 1 facing the workpiece W,
As will be described later, a conductive pattern 13 in which the metal base 11 is exposed in a required pattern is formed, and a current from the machining power source 6 is applied to the conductive pattern of the electrode tool 1 with the electrolytic solution interposed therebetween. 13 and the workpiece W, the workpiece W at the portion facing the conductive pattern 13 is eluted by an electrochemical reaction, and is equivalent to the conductive pattern 13 of the electrode tool 1 on the surface of the workpiece W. The dynamic pressure groove of the pattern of FIG. The magnitude of the current flowing between the workpiece W and the electrode tool 1 is measured every moment by an ammeter (not shown), and its energizing time is also measured by a timer (not shown). It is controlled based on data on the relationship between the current density and the groove processing amount (depth) measured in advance by a known method, whereby a dynamic pressure groove having a required depth is formed on the surface of the workpiece W. Is done.

Now, the electrode tool 1 is, as shown in FIG.
A resin layer 12, which is a non-conductive material, is formed in a required pattern on the surface of the metal base 11 facing the workpiece W, and the resin layer 12 is covered with the resin layer 12, so that the remaining region is exposed to the outer surface. Having a conductive pattern 13 formed thereon.

The resin layer 12 is formed by spraying fine particles of a resin having excellent insulating properties, such as a polyimide resin, onto the surface of the base 11 and then fixing the fine particles by baking. That is, as schematically shown in FIG.
The polyimide resin fine particles P having a particle size of about 1 to several μm are formed into a slurry and sprayed onto the surface of the base 11 while controlling the fine nozzles N to move in a required pattern by, for example, a servo mechanism. At this time, an adhesive layer or the like may be formed on the surface of the substrate 11 by printing or the like in advance according to the pattern of the resin layer 12. Then, the resin fine particles are applied to the base 11 in a required pattern.
After being adhered to the surface of the substrate 11, the whole is heated and baked to fix the resin fine particles on the surface of the base 11, and the resin layer 12
Get. The thickness of the resin layer 12 is about several tens of μm.

As another method of forming the resin layer 12, as shown in FIG. 4A, the same resin fine particles P as described above are adhered to the entire surface of the substrate 11 on which the resin layer 12 is to be formed. After the resin layer 120 fixed by baking is formed, as shown in FIG. 4B, a resist film R having a required pattern is formed on the surface of the resin layer 120 by a photolithography technique or the like. It is also possible to adopt a method of obtaining the resin layer 12 of a required pattern by removing an unnecessary portion of the resin by a method such as laser light irradiation.

According to the above-described embodiment of the present invention, the non-conductive material for covering the surface of the metal base 11 and exposing only the dynamic pressure groove-shaped conductive pattern 13 is formed by adhering resin fine particles. The base 1 is formed by the resin layer 12 fixed to the base 11 by baking.
1 becomes extremely strong, and the peeling life can be greatly improved as compared with the case where the substrate 11 is coated with a non-conductive material by conventional resist film coating or the like.

Here, the above electrode tool 1 is one to which the invention according to claim 1 is applied. Next, an electrode tool to which the invention according to claim 2 is applied will be described. The dynamic pressure groove machining apparatus according to the second aspect of the present invention is the same as that shown in FIG. 1 except for the structure of the electrode tool. FIG. 5 is a longitudinal sectional view of the electrode tool 10. This electrode tool 10
Is obtained by attaching a resin sheet 102 to the surface of a metal base 11 similar to that of the previous example using an adhesive or the like.
The feature is that the conductive pattern 13 similar to the previous example is formed.

Resin sheet 102 according to this embodiment
Is patterned in advance. As shown in FIG. 6, before bonding to the base 11, holes 130 having the same pattern as the conductive patterns 13 are formed in a resin sheet material 102 'having a thickness of about 100 μm by shot blasting or the like. Such a pre-patterned resin sheet 102 is adhered to the base 11 using an appropriate adhesive to form the resin sheet 1 on the base 11.
02 can easily have a strong adhesive strength,
Also in this embodiment, compared to the case where the base 11 is coated with a non-conductive material by a conventional resist film coating or the like,
The peeling life can be greatly improved.

In this embodiment, even if the operation of fixing the resin sheet 102 to the base 11 fails, the base 11 itself can be reused.
There is also an advantage that the manufacturing process of the electrode tool 1 can be simplified.

In each of the above embodiments, an example is shown in which the present invention is applied to the step of forming the thrust dynamic pressure groove. However, the present invention is equally applicable to the step of forming the radial dynamic pressure groove. Of course.

[0025]

As described above, according to the first aspect of the present invention, a dynamic pressure groove is formed on a surface of a metal base as an electrode tool for forming a dynamic pressure groove in a workpiece by electrolytic processing. Since a non-conductive material covering a part of the surface of the substrate to expose the conductive pattern with a pattern is used as a resin layer formed by attaching and baking resin fine particles, a conventional resist film coating or resin coating is used. Compared to the case where the substrate is covered with a non-conductive material by embedding, the adhesion to the substrate becomes stronger, and the peeling life can be greatly improved.

According to the second aspect of the present invention, a conductive pattern is formed on a surface of a metal base by using a dynamic pressure groove pattern as an electrode tool for forming a dynamic pressure groove on a workpiece by electrolytic processing. Since a non-conductive material covering a part of the surface of the base is exposed to expose a resin sheet in which a hole of a pattern of a dynamic pressure groove is previously formed is fixed to the surface of the base by sticking or the like, the above-described structure is used. Similar to conventional electrode tools of this type, the adhesion of the non-conductive material to the substrate is stronger than that of conventional electrode tools, and the peeling life can be greatly improved. It is also effective for simplifying the manufacturing process.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the entire configuration of a dynamic pressure groove machining apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the electrode tool 1 in FIG.

FIG. 3 is an explanatory view of an example of a method of manufacturing the electrode tool 1 of FIG.

FIG. 4 is an explanatory view of another example of the method for manufacturing the electrode tool 1 of FIG.

FIG. 5 is a longitudinal sectional view of an electrode tool 10 used in the invention according to claim 2;

6 is an explanatory diagram of an example of a method for manufacturing the electrode tool 10 of FIG.

[Explanation of symbols]

 Reference Signs List 1 electrode tool 11 base 12 resin layer 13 conductive pattern 2 processing tank 3 electrolyte tank 4a, 4b piping 5 pump 6 processing power supply 102 resin sheet 130 hole

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshiki Fujii 3-5-8 Minamisenba, Chuo-ku, Osaka-shi, Osaka F-term (reference) 3C059 AA02 AB01 DA13 DB02 DC01 HA00 3J011 CA02 DA02

Claims (2)

[Claims] 1. A workpiece on which a dynamic pressure groove is to be formed on a surface,
An electrode tool having a conductive part of a predetermined pattern exposed on the surface is immersed in the electrolyte so as to face each other, and while the workpiece and the electrode tool are connected to the positive electrode and the negative electrode, respectively, and energized, In a dynamic pressure groove processing apparatus for forming a dynamic pressure groove having a shape corresponding to an exposed pattern of a conductive portion of an electrode tool on a surface of a workpiece by flowing an electrolytic solution, the electrode tool has a surface of a metal base. Characterized by having a structure in which a region other than the above-mentioned predetermined pattern is covered by a resin layer formed by attaching and baking resin fine particles. 2. A workpiece on which a dynamic pressure groove is to be formed on a surface,
An electrode tool having a conductive part of a predetermined pattern exposed on the surface is immersed in the electrolyte so as to face each other, and while the workpiece and the electrode tool are connected to the positive electrode and the negative electrode, respectively, and energized, In a dynamic pressure groove processing apparatus for forming a dynamic pressure groove having a shape corresponding to an exposed pattern of a conductive portion of an electrode tool on a surface of a workpiece by flowing an electrolytic solution, the electrode tool has a surface of a metal base. Wherein the predetermined pattern of holes is formed in advance and has a structure in which a resin sheet is fixed.