JPS6138217A - Method for manufacturing fluid bearing - Google Patents

Abstract

PURPOSE:To process fluid compression concave portions having multistage shape where bore becomes smaller sequentially in high accuracy by repeating forming and etching of resist films sequentially by using photo-etching method. CONSTITUTION:When forming multi-stage fluid compression concave portions 3, resist films 4 coating is applied on portions which become minimum diameter portions 3a first and an exposed inner circumferential face where resist films are not formed is etched to a predetermined depth. Next second resist films 5 coating is applied on portions which becomes first step portions 3b while resist films 4 are provided on the minimum diameter portions 3a. And an exposed inner circumferential face where neither of the resist films 4, 5 is formed is etched to a predetermined depth. And further, third resist films 6 coating is applied on portions which become second step portions 3c while the resist films 4, 5 are provided on the minimum diameter portions 3a and the first step portions 3b.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method of manufacturing a fluid bearing that supports a shaft in a 70-ring state.

(Prior art) Conventionally, a fluid such as oil or air is interposed between the inner periphery of the bearing surface and the shaft, and the shaft is supported in a 70-ring state by the fluid compression pressure generated as the shaft rotates. Hydrodynamic bearings are known. The inner periphery of this bearing surface has a fluid compression recess whose inner diameter gradually decreases along the rotational direction of the shaft, and as the shaft rotates, the fluid flowing due to its viscous resistance is compressed within the recess, and the shaft A repulsive force is generated that urges the object toward the center, causing it to float.

However, the fluid compression recesses are formed to a depth of several microns to several tens of microns, and must be provided so that the depth gradually changes, making machining difficult and hindering mass production.

As a conventional method for forming the fluid compression recess, a method has been adopted in which the inner circumferential surface of the bearing is sequentially ground using a rotating grindstone. However, in this method, the recess formed on the inner periphery is arc-shaped, and the shape that contributes to fluid compression is half of the recess, so the repulsive force generated by this recess is small and the floating effect is reduced. The bearing load that is not sufficiently obtained and is allowed is also small.

(Object of the Invention) In view of the above circumstances, the present invention provides a method for manufacturing a fluid bearing that makes it possible to form a multi-stage fluid compression recess that has a shape that is difficult to form by machining, and that makes it possible to obtain a high fluid repulsion force. The purpose is to provide

(Structure of the Invention) In the manufacturing method of the present invention, first, a resist film is coated only on the portion where the bearing minimum diameter portion is to be formed, and then the inner circumferential surface is etched to the depth required for the first step portion. In addition to the above-mentioned resist film, a resist film is coated on the area where the first step part is to be formed, and the remaining inner peripheral surface is etched to the depth required for the second step part, and the above step is completed to form the desired step part. This is characterized in that a multi-stage fluid compression recess is formed on the inner periphery of the bearing surface by repeating the process until the bearing surface is compressed.

(Effects of the Invention) According to the present invention, by sequentially repeating the formation and etching of a resist film using a photo-etching method, a fluid compression recess having a multi-stage shape whose inner diameter is gradually reduced can be processed with high precision. In the multi-stage fluid compression recess having this shape, the entire recess contributes to the fluid compression action, and a high repulsion force is obtained, making it possible to increase the bearing load and mass production processing. It has the following advantages.

(Example) Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a sectional view of a hydrodynamic bearing manufactured by the method of the present invention, and the shape of the recess is exaggerated. Moreover, FIGS. 2 to 4 are partial sectional views showing the manufacturing steps in order.

The fluid bearing 1 is provided with a plurality (six in the illustrated case) of multistage fluid compression recesses 3 whose inner diameters become smaller in sequence along the rotational direction A of the shaft 2 on its inner peripheral bearing surface. Further, the multi-stage fluid compression recess 3 is formed in three stages, a first stage part 3b, a second stage part 3C, and a third stage part 3d, with respect to the minimum diameter part 3a. For example, each step 3b; 3c of the multi-stage fluid compression recess 3
, 3d are each about 6μ deep, and the deepest part is about 20μ.
Form it so that it becomes μ.

Its formation begins with the smallest diameter portion 3a as shown in FIG.
Coat the resist film 4 on the area where
~The exposed inner peripheral surface on which the film 4 is not formed is etched to a predetermined depth. This resist film 4 has resistance when etching the inner circumferential surface of the bearing, and can be prepared by applying a liquid resist solution by spraying with a brush or masking and drying it, or by preparing a film in advance. Coating by pasting the formed material. Further, the etching process is performed by chemical etching, electrolytic etching, dry etching, etc., and etching is performed to a depth required for the first step portion 3b.

Next, as shown in FIG. 3, while the resist film 4 is still provided on the minimum diameter portion 3a, a second resist film 5 is applied to a portion of the recess formed by the etching process that will become the first step portion 3b. Coating.

The formation of this second resist film 5 is similar to that of the first resist film 4, and for example, with the portion other than the first step portion 3b covered with a mask film, a resist solution is applied by brushing or spraying. Formed by coating. Subsequently, the exposed inner peripheral surface on which both resist films 4.5 are not formed is etched to a predetermined depth. The etching process is
It is etched by the same process as the first etching, and the second
Etch to the depth required for the stepped portion 3C.

Furthermore, while the resist films 4 and 5 are still provided on the minimum diameter portion 3a and the first step portion 3b, a portion of the recess formed by the above etching process, which will become the second step portion 3C, is etched as shown in FIG. A third resist film 6 is coated. The third resist film 6 is formed in the same manner as the second resist film 5, and for example, with the portion other than the second step portion 3C covered with a mask film, a resist solution is applied by brushing or spraying. Formed by coating.

Subsequently, the exposed inner peripheral surface on which the resist film 4.5.6 is not formed is etched to a predetermined depth to form the third step portion 3d. In the etching process, etching is performed by the same process as the etching described above, and etching is performed to a depth required for the third step portion 3d.

As described above, the resist films 4, 5. ．． 6 and etching are repeated to form the third step portion 3d, the resist film 4.5.6 is dissolved and removed using an organic solvent or the like, thereby forming the multi-stage fluid compression recess 3 in a desired shape. A hydrodynamic bearing 1 can be obtained.

The multi-stage fluid compression recess 3 may be formed on the bearing inner circumferential surface of the fluid bearing 1 parallel to the axis, or may be formed at an angle so as to be inclined with respect to the axis. It may be formed in a V-shape or a W-shape in which the direction of inclination changes on both sides with the central part of the axis as a boundary.

In that case, the hydraulic pressure generating part is located in a spiral shape with respect to the shaft 2,
Since they are evenly distributed on the circumference, the shaft 2 rotates more stably. Further, fluid can be smoothly supplied between the bearing 1 and the shaft 2.

Note that the number of multistage fluid compression recesses 3 provided on the inner circumferential surface of the bearing is as follows:
In addition to the above-mentioned six divisions, the number of stages may be appropriately set as necessary, and the design of the number of stages may be changed as appropriate. Also, especially
When forming the multi-stage fluid compression recess 3 with high precision, a photoresist film is formed on the entire inner peripheral surface, and this photoresist film is exposed through a photomask having a predetermined pattern and developed. Alternatively, a photoresist technique that can accurately coat a resist film in a predetermined pattern may be used.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a hydrodynamic bearing manufactured by the method of the present invention with its four parts exaggerated, and FIGS. 2 to 4 are partial cross-sectional views sequentially showing the manufacturing steps. 1...Fluid bearing 2...Shaft 3...Multi-stage fluid compression recess 3a...
Minimum diameter portion 3b...First step portion 3G...
...Second step section 3d...Third step section 4.5.6...Resist film Fig. 1 Fig. 2

Claims (1)

[Claims] (1) A method for manufacturing a fluid bearing in which a plurality of multi-stage fluid compression recesses are formed on the inner periphery of the bearing surface, the inner diameter of which decreases sequentially along the rotational direction of the shaft, where the minimum diameter portion of the bearing is to be formed first. After coating the resist film on only the resist film, the inner circumferential surface is etched to the depth required for the first step, and then in addition to the resist film, a resist film is coated on the area where the first step is to be formed. The remaining inner circumferential surface is etched to a depth required for the second step, and the above steps are repeated until the desired step is formed, thereby forming a multi-stage fluid compression recess on the inner circumference of the bearing surface. A manufacturing method for hydrodynamic bearings.