JPS63235721A - Manufacture of dynamic pressure groove bearing - Google Patents

Abstract

PURPOSE:To make it possible to reduce the possibility of breakage due to micro-defects, by heating a grooved ceramic material under the atmosphere of unoxidation so as to remove internal stress. CONSTITUTION:The outer surface of a ceramic material formed thereon with a protective film is subjected to a grooving process by use of shot-blast. Thereafter, the removable of the protective film is carried out by a suitable process depending upon the kind of resin used therefor. After grooving by the shot-blast process, the ceramic plate is heated at a temperature of 1,000-1,800 deg.C. C under the atmosphere of unoxidation using such as argon, hydrogen or vacuum. Accordingly, a warp of the ceramic plate is corrected, and simultaneously, internal stress which is produced in the ceramic late during the grooving process may be also removed, thereby it is possible to reduce the possibility of breakage due to micro-defects.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a hydrodynamic croup bearing in which a groove for generating hydrodynamic pressure is provided in one of the opposing bearings and the journal. In particular, the present invention relates to a method of manufacturing a dynamic pressure group bearing in which the member provided with the groove for generating dynamic pressure is made of ceramic.

(Prior Art) A dynamic pressure group bearing forms a shallow groove of several gm to a hundred and several tens of gm on one of two surfaces that perform relative rotational motion, and the relative rotation J! The bearings support the load by drawing fluid along the shallow grooves and generating dynamic pressure according to the load.The bearings include planar spiral group bearings, herringbone bearings, conical spiral group bearings, and spherical spiral bearings. Group bearings are known.

Figure 2 (a) is a partially fragmented vertical cross-sectional view of a flat spiral group bearing, and Figure 2 (b) is a Y-plane view showing the shape of the grooves in the bearing plate at the end of the 0-rotation shaft (1). is the rotation axis (1)
A flat plate (2) is fixed as a journal at right angles to the axis of the bearing plate (3) on the fixed side opposite to this flat plate (2).
) are arranged, and a plurality of spiral grooves (4) are formed on the surface of the bearing plate (3) facing the journal.

When the rotation axis (1) rotates in the direction of the arrow in IA, that is, in the counterclockwise direction, the fluid in contact with the flat plate (2) rotates together with the flat plate (2), and at the same time the spiral groove (4
), the fluid flows inward from the outer periphery, and dynamic pressure of the fluid is generated between the flat plate (2) and the bearing plate (3), causing pressure to flow at the end of the rotating shaft (1). Fixed flat plate (2
) rotates without substantially contacting the bearing plate (c).

Conventionally, it has been said that it is desirable for this spiral group to have a groove depth of several tens of gm to over a hundred μm, depending on the viscosity of the fluid interposed between the opposing surfaces. In principle, there are various methods for forming this spiral group, including (1) plating process, (2) electric discharge machining method, (2) chemical etching method, (2) shot blasting method, and (3) ultrasonic machining method. Proposed.

The plating build-up method is a method in which the surface where the spiral group is to be formed is smoothed, the part where the spiral group is to be formed is covered with an insulating material, the surface of the part corresponding to the land is exposed, and the land is formed by electroplating. In Although,
The material constituting the surface on which the spiral group is to be formed is limited to conductive metal materials.

In the electric discharge machining method, the member on which the spiral group is to be formed is immersed in oil to serve as one electrode, the other electrode is placed near the position where the spiral group is to be formed, and a high-frequency potential is applied between the two. This method creates a groove that corresponds to a spiral group.

In the chemical etching method, the area corresponding to the land on the surface of the member where the spiral group will be formed is coated with a chemically stable substance (generally synthetic resin), immersed in a corrosive liquid, and the spiral group is formed by corrosion. This is a method in which groups are formed and then the material covering the surface of the land is removed using a cleaning solution.

The shot blasting method is a method disclosed in JP-A-57-15121 and JP-A-60-14615, in which a smooth ceramic sox coating is applied to the surface of the metal, which corresponds to a land. In this method, the part is covered with a metal mask or resin mask, and the ceramic coating is removed by shot blasting to expose the metal surface, which becomes the bottom surface of the spiral group.

(Problem to be solved by invention) As a bearing that supports radial load and thrust load, H
rtIn theory, there are various bearings such as rolling bearings, sliding bearings (hydrodynamic bearings, hydrostatic bearings), and magnetic bearings. Therefore, the hydrodynamic group bearings related to the present invention are also superior to other types of bearings. If bearing performance is not provided, the practical value will be diminished.

Conventional hydrodynamic group bearings are unable to exhibit the high load capacity suggested by theoretical studies, and are difficult to process opposing surfaces and spiral groups, and are expensive. It was only used for special purposes such as disks, magnetic disks, and record players.

In addition, the specific manufacturing technology is rarely published, and even the method described in the May 24, 1982 issue of Nikkei Mechanical, that is, the processing method of the various Subairal Group mentioned above, can also be used to achieve high performance. It has not been easy to obtain a dynamic pressure group bearing with performance.

As a result of various researches by wood inventors, in dynamic pressure group bearings, in order to increase its load capacity.

We confirmed that it is important not only to increase the accuracy of the facing surfaces of the hydrodynamic group bearings, but also to maintain the initial accuracy so that the accuracy does not deteriorate even when a certain dynamic pressure is generated. Furthermore, based on this knowledge, we conducted intensive studies on a method for manufacturing dynamic pressure group bearings at low cost and efficiently, and have already established the technology shown in Japanese Patent Application No. 61-103027 and Japanese Patent Application No. 61-119081. That is, in Japanese Patent Application No. 61-103027, as a technique for forming grooves in the dynamic pressure group, at least one of the bearing and the journal is made of ceramic, and one of the bearing and the journal is made of ceramic. After coating the photosensitive resin on the opposite sides of the member and drying it, it is exposed through a patterned film.
They report a method in which development is then performed, the photosensitive resin in the unexposed areas is removed, and shot blasting is performed. Furthermore, in Japanese Patent Application No. 119081/1981, the same technology for forming grooves in the dynamic pressure group is disclosed. We reported a method in which a pattern was formed using a paint that was replaced with a previously used paint using a screen printing method, and after drying, shot blasting was performed.

(Problems to be solved by the invention) However, the inventors of the present invention
When grooves are formed on a ceramic member by shot blasting as shown in Publication No. 27 and Japanese Patent Application No. 119081/1980, the ceramic member may have a very small amount of grooves or a convex curve on the shot blasted surface. I discovered that.

This warpage tends to increase as the thickness of the plate becomes thinner, and according to the experimental results of the inventors of the woodwork, for example, in a silicon carbide sintered body with a diameter of 60 mm and a thickness of 10 mm, the warping tends to increase as the thickness of the plate decreases. Although no change was observed in the warpage, the diameter was 60 mm.

For a silicon carbide sintered body with a thickness of 2 mm, from 0.71 Lm to 1
．． It warped to 2pm. There has never been a reported case of a member made of high-strength ceramic warping due to mechanical grooving such as shot blasting. The reason why there are no previous reports is probably that the actual measured warpage f1 is extremely small.

Shot blasting imparts ceramic components.

We believe that the main reason was that the external force was extremely small, so there was a preconception that the ceramic member would not be deformed. In any case, in order for the hydrodynamic group bearing to work properly, it is desirable that the ceramic member be returned to its unwarped state even after grooving by shot blasting, as it was before grooving. .

(Means for Solving the Problem) As a result of research conducted from various angles, the present inventors found that in order to increase the load capacity of a hydrodynamic group bearing, it is necessary to It was confirmed that it is important not only to improve the accuracy of the bearings but also to maintain the initial accuracy so that the accuracy does not deteriorate even when a predetermined dynamic pressure is generated. The present inventors have newly found that it is possible to undo the warpage of the ceramic member forming the journal by a simple means, and have completed the present invention.

That is, in the present invention, a groove for generating dynamic pressure is provided in either one of the facing bearing and the journal, and relative interlocking is performed with a fluid interposed in a minute gap between the bearing and the journal. A method for manufacturing a hydrodynamic group bearing, the method comprising the following sequence of steps (a) to (e).

(a) manufacturing at least one of the bearing and the journal from ceramic; (b) forming a protective film on opposing surfaces of either the bearing or the journal and a ceramic member; Steps: (tl,) a step of performing shot blasting on a portion of the surface where there is no protective film (a) to form a groove; (d) a step of removing the protective film on the surface.

(c) a step of heat-treating the shot blasted member in a non-oxidizing atmosphere;

Next, the present invention will be explained in detail.

According to the manufacturing method of the present invention, the ceramic member is made of silicon carbide, silicon nitride, zirconia, aluminum, mullite,
The material is at least one selected from sialon, and silicon carbide and silicon nitride are particularly preferred because they have high strength and good thermal conductivity.

The fine powder of ceramic νx is molded into a disk shape, the resulting molded body is fired, and the disk (the surface where the grooves for generating dynamic pressure are to be machined) is lapped to make it smooth. Make it a flat surface with no undulations. Next, the smooth ceramic disk is cleaned using a solvent such as trichloride, and then
Washed with wt% NaOH solution for 5 min, then 10% H
Neutralize with 2SO4 solution and wash with warm water at 60°C to bring the surface of the ceramic disc to a normal state. Next, maintain the normal surface of the obtained ceramic disk:lll1!
form.

The protective film may be at least one selected from paints containing resin or rubber as a main component, film-like photosensitive resins, and liquid photosensitive resins. Embodiments of these protective films are discussed in more detail below.

First, the resin that is the main component of the paint is at least one selected from epoxy resins, urethane resins, unsaturated polyester resins, silicon resins, fluorine resins, and polyimide resins. Rubbers that are the main components of paints include butadiene rubber, isoprene rubber, natural rubber, chloroprene rubber, acrylonitrile-butadiene copolymer rubber, acrylonitrile-isoprene copolymer rubber, urethane rubber, urethane-epoxy J (
At least one selected from polymer rubber, fluororubber, and silicone rubber.

The protective film is formed by screen printing a paint whose main component is resin or rubber.

Next, the dry film-like photosensitive resin is unsaturated)
The main component is an acrylic copolymer with
For example, it is commercially available under the names of Riston manufactured by DuPont, Laminar manufactured by Dynachem, and Footec manufactured by Hitachi Chemical. In the case of any dry film, the photosensitive resin is first laminated on the surface of the desired ceramic member, exposed to light with a mercury lamp through a patterned film, and then the unexposed areas are removed with a developer. By removing it, a protective film is formed.

Finally, liquid photosensitive resins include water-soluble ones made by adding a photosensitive material such as ammonium chromate to polymers such as charcoal, polyvinyl alcohol, shellac, and casein, or polyvinyl cinnamate, cyclized rubber, etc. It is an oil-soluble type such as an azide type. In the case of liquid photosensitive resin, the viscosity is adjusted with a solvent, and the photosensitive resin is applied to the surface of the desired ceramic member using a spinner, roll coater, or dip, and then dried, followed by pattern formation. After exposing the finished film to a mercury lamp, a protective film is formed by removing the unexposed areas with a developer.

After forming a protective film on the surface of the ceramic by the above method, grooves are formed by shot blasting. The particles used for shot blasting can be made of various substances such as silicon carbide, alumina, and silicon oxide. If the grooves are deep, particles with a large diameter are used, and if the grooves are shallow, particles with a small diameter are used.

The shot time is preferably 1 to 3 minutes.

The removal of the M-retaining film must be performed by selecting an appropriate method depending on the resin used for the protective film. In many cases, there is a special exfoliating solution available, which you can use.

After the grooves have been formed by the shot blasting process, the ceramic plate is heat treated at a temperature of 1000 to 1800 DEG C. in a non-oxidizing atmosphere such as argon, hydrogen, helium, or vacuum. At the same time, the warpage of the ceramic plate is corrected, and at the same time, the internal stress in the ceramic plate that was generated when the groove was processed is also released.

(Example) (1) Molding process After forming fine powder of silicon carbide (average particle size 0.15 pm) into a disk shape, the resulting formed body was fired at normal pressure and high temperature,
The disk had a diameter of 50 mm and a thickness of 2 mm. In addition, the surface of one disc (the surface on which the grooves for generating dynamic pressure are to be machined) was finished by lapping to have a surface roughness of 0.1 gm or less and a waviness of 1 JLITl or less.

(2) Pretreatment The smooth silicon carbide disk obtained in the above molding step was cleaned with trichlene and heated with 20 wt%N at 90-100°C.
Degreasing was performed by immersing it in an aOH aqueous solution for 5 minutes. next,
Wash with warm water at 60°C for 5 minutes, then wash with 10wt% H2
So, neutralize with an aqueous solution and wash with warm water at 60°C,
The surface of the ceramic disc was kept clean. As shown in Table 1, the warpage at this time was 0.71Ltn.

(3) Coating process A butyl cellosolve solvent was added to the urethane-epoxy ink, and the viscosity was adjusted to about 200 PS to prepare a printing coating. Printing was done using a stainless acid screen.

First, set the ceramic disk in the printing jig with the bearing surface facing up, then set the screen in the specified position.
The viscosity-adjusted paint was cooled on a screen 7, and the squeegee was swept to print the paint on the bearing surface.

(4) After curing, remove the ceramic rough disk from the printing jig, and then
It was held for 10 minutes in the open oven to dry and harden.

The film thickness of the resulting paint was about 15 JLm.

(5) Shot blasting was performed for 120 seconds using silicon carbide particles with an average particle diameter of 700 mesh on the surface of a disc in which the smooth surface of the ceramic was covered with a resin layer in a spiral pattern. The average groove depth at this time was 10 pLm.

(6) Exfoliation process After spraying 5 wt% NaOH aqueous solution for 2 minutes,
Brush to remove paint adhering to the bearing surface.
Washed with warm water at 60°C for 5 minutes. The warpage of the ceramic plate at this time is shown in Table 1.

It was 1.2 lm.

(7) Heat treatment process The warped ceramic disc is heated from room temperature to 70'C while maintaining the pressure at about 1 atm in an Ar atmosphere.
The temperature was increased at a rate of 5°C/min until
After increasing the temperature from 00°C to 1600°C at a rate of 8°C/min, heat treatment was performed at 1600°C for about 1 hour. As shown in Table 1, the warpage of the ceramic disk after the heat treatment was 0.7 m.

As is clear from Table 1, the waviness of the ceramic disk was less than 1 gm after the pretreatment step FM, and the warp exceeding Igm was measured after groove processing by shot blasting. However, by performing heat treatment after grooving 1, the warpage returned to 1 gm or less. This shows that the present invention is excellent as a method for correcting warpage.

Note that in the method for correcting warpage of the present invention, the protective film during groove processing by shot blasting is not limited to only the paint containing resin or rubber as the main component as shown in the above embodiments, but also the protective film. The same results can be obtained even if the photosensitive resin is made of a dry film or a liquid photosensitive resin.

Table 1 (Effects of the invention) In the wood Q Ijl, the member in which the groove for generating dynamic pressure of the dynamic pressure group bearing is to be formed is made of ceramics.
t, so even when large dynamic pressure occurs,
It is possible to manufacture a dynamic pressure group bearing in which the shape of the groove for generating dynamic pressure is not deformed and can appropriately generate dynamic pressure even in a high load region.

In particular, by forming a protective film on the surface of the ceramic on which the grooves for generating dynamic pressure are to be formed, and then applying shot blasting treatment, it is possible to form the grooves or simply make the cylinder. Warping occurs, although it is very slight. Such warping that occurs in the ceramic ink member can be corrected by applying heat treatment in a non-oxidizing atmosphere.

Furthermore, the manufacturing method of the present invention can also reduce the probability of breakage due to micro defects since the internal stress remaining as a result of correcting the warpage of the ceramic member is removed.

In this way, the first dynamic pressure group bearing that originates from wood! According to the A construction method, there is extremely little warpage, the precision of opposing surfaces is high, and even when a predetermined dynamic pressure is generated, it is possible to maintain the initial precision without degrading the precision. Since we can provide pressure group bearings, the effect of contributing to industry is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a chart showing the warping of the surface of ceramics used in the implementation of the present invention, Fig. 2(a) is a partial vertical cross-sectional view of a planar spiral group bearing, and Fig. 1) is a hydrodynamic group bearing. FIG. Patent applicant: IBIDEN Co., Ltd. Agent
Person Patent Attorney Takeshi Hiroe Figure 1 (b) ntl) - Anti-Soviet line (C), mysterious place 1! Anti-Soviet Part 2rIII (b)

Claims (1)

[Claims] 1) A groove for generating dynamic pressure is provided in either one of the bearing and the journal, which face each other, and the bearing and the journal face each other with a fluid interposed in a minute gap. A method for manufacturing a dynamic pressure group bearing in which motion is performed, the method comprising the following sequence of steps (a) to (e). (a) manufacturing at least one of the bearing and the journal from ceramic; (b) forming a protective film on opposing surfaces of the ceramic member of either the bearing or the journal; (c) performing shot blasting on a portion of the surface where there is no protective film to form a groove; (d) removing the protective film on the surface; (e) performing the shot blasting. 2) The member provided with the grooves is made of at least one material selected from silicon carbide, silicon nitride, zirconia, alumina, mullite, and sialon. A method for manufacturing a dynamic pressure group bearing according to claim 1, characterized in that: 3) A patent characterized in that the protective film is at least one selected from the group consisting of a resin or rubber-based paint, a film-like photosensitive resin, and a liquid photosensitive resin. A method for manufacturing a dynamic pressure group bearing according to claim 1.