JPS62278313A - Manufacture of dynamic pressure group bearing - Google Patents

Abstract

PURPOSE:To accurately form a grooved pattern, by forming a member, in which a groove for generating a dynamic pressure must be formed, by ceramics and improving durability and reliability while printing the spiral pattern on a bearing surface on which the groove is formed. CONSTITUTION:A groove for generating a dynamic pressure is provided in either a bearing or a journal opposed to each other, further a relative motion is performed in a condition that fluid is interposed in a fine gap between both the bearing and journal. When the dynamic pressure group bearing is manufactured as in the above, either the bearing or the journal is prepared by ceramics, further paint, mainly composed of resin or rubber, is printed on mutually opposed surfaces of a ceramics made member. And a groove is formed by hardening the paint further applying a shot blast process to a part printing no paint, thereafter the paint is removed. Here the printing is performed by using a screen 13 which forms a spiral pattern 16 by a screen part 14 and a no-hole part 15.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Application Field] The present invention provides a dynamic pressure generating system in which a groove for generating dynamic pressure is provided in either one of a bearing and a journal facing each other. The present invention relates to a method for manufacturing a group bearing, and more particularly, the present invention relates to a method for manufacturing a dynamic pressure group bearing in which the member provided with the groove for generating dynamic pressure is made of ceramics.

[Prior art] A dynamic pressure group bearing forms a shallow groove of several μm to several hundred μm on one of two surfaces that perform relative rotational motion, and fluid flows along this shallow groove due to the relative rotational motion. The bearings are designed to support the load by drawing in the bearings and generating dynamic pressure according to the load.As the bearings, there are known planar spiral group bearings, herringbone bearings, 1 cylindrical spiral group bearings, 9 spherical spiral group bearings, etc.

FIG. 5(a) is a partially exploded vertical cross-sectional view of the planar spiral group bearing, and FIG. 5(a) is a plan view showing the shape of the groove in the bearing plate. A flat plate 2 is fixed to the end of the rotating shaft 1 as a journal at right angles to the axis of the rotating shaft 1. A bearing plate 3 on the fixed side is arranged opposite to this flat plate 2. versus.

A plurality of spiral grooves 4 are formed on the facing surface. Here, when the rotating shaft 1 rotates in the direction of the arrow 5, 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 fluid flows along the spiral groove 4 from the outer periphery to the inside. As a result, a fluid dynamic pressure is generated between the flat plate 2 and the bearing plate 3, and the flat plate 2 fixed to the end of the rotating shaft 1 rotates without substantially contacting the bearing plate 3.

FIG. 5(C) is a partially exploded cross-sectional view of a type of dynamic pressure group bearing called a herringbone bearing, and the rotating shaft is shown in a transparent state. A radial bearing is formed between the journal, which is the outer peripheral surface of the rotating shaft 1, and the fixed-side bearing 6, and a herringbone (fish bone)-shaped groove 7 (black part) is formed on the inner peripheral surface of the bearing 6. has been done. In this herringbone bearing, when the rotating shaft 1 rotates in the direction of the arrow 5, fluid is drawn into the center from both sides of the bearing 6, so a lubricating film of fluid is formed between the journal of the rotating shaft 1 and the bearing 6. Supports radial loads.

FIG. 5 (d+ is a conical spiral group bearing,
The end of the rotating shaft 1 is a truncated conical journal with a spiral groove 4 formed on its surface, and a bearing 8 is formed corresponding to the conical shape.
Fluid is drawn into the bottom of the recess 9 of the bearing 8 and the journal surface in which the spiral groove 4 is formed by relative rotational movement between the bearing 8 and the recess 9 formed on the side, supporting not only thrust loads but also radial loads. be able to.

Figure 5 tel is a spherical spiral group bearing,
The end of the rotating shaft 1 is made into a spherical journal, a spherical recess 11 is also formed in the bearing 10, and a spiral groove 12 is provided on the journal surface of the rotating shaft. This spherical spiral group bearing can also support thrust loads and radial loads at the same time. In any case of the dynamic pressure group described above, the surface forming the spiral group or herringbone group may be either the journal side or the bearing side. Adjacent lands 13 must be smooth planes or curved surfaces, and the opposing surfaces on the side where no spiral group or herringbone group is formed must also be smooth planes or curved surfaces like the lands 13. It won't happen. It is known that such hydrodynamic group bearings can theoretically support significantly greater loads than hydrodynamic belly bearings without groups (eg, tilting pad bearings).

Hereinafter, in this specification, groups (grooves) formed in a dynamic pressure group bearing, such as a spiral group and a herringbone group, are collectively referred to as a spiral group. Conventionally, it has been considered desirable for this spiral group to have a groove depth of several μm to several hundred μm, depending on the viscosity of the fluid interposed between the opposing surfaces. In principle, various methods have been proposed for forming this spiral group, such as ■ plating build-up method, ■ electric discharge machining method, ■ chemical etching method, ■ shot blasting method, and ■ ultrasonic machining method. . 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. The material constituting the surface on which the spiral group is to be formed is limited to conductive metal materials.

In the electrical discharge machining method, the member on which the spiral group is to be formed is immersed in oil, one electrode is placed, 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 to create a spark. This method creates a groove corresponding to a spiral group.

In the chemical etching method, the part of the surface of the member on which the spiral group will be formed, which corresponds to the land, is covered with a chemically stable substance (generally synthetic resin) and immersed in a corrosive liquid, and the spiral group is formed by corrosion. This is a method in which 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 coating is applied to the surface of the metal, and the portion corresponding to the land is covered with metal. In this method, the metal surface is covered with a mask or a 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.

[Problems to be solved by the invention]

In principle, there are various types of bearings that support radial loads and thrust loads, such as rolling bearings, sliding bearings (hydrodynamic bearings, hydrostatic bearings), and magnetic bearings. Unless bearings have superior bearing performance compared to other types of bearings, their practical value will be diminished.

Conventional hydrodynamic group bearings cannot exhibit the high load capacity suggested by theoretical studies, and it is difficult and expensive to process opposing surfaces and spiral groups. It was only used for special purposes such as discs, TJf1 discs, and record players.

In addition, the specific manufacturing technology is rarely published. It has not been easy to obtain a dynamic pressure group bearing with performance.

[One Means to Solve the Problem] As a result of various studies, the present inventors have found that in order to increase the load capacity of hydrodynamic group bearings, it is necessary to improve the accuracy of the opposing surfaces of the hydrodynamic group bearings. We confirmed that it is important not only to increase the accuracy, but also to maintain the initial accuracy so that the accuracy does not deteriorate even when a predetermined dynamic pressure is generated. Based on this knowledge, we also developed a dynamic pressure group bearing at a low cost. The idea was to come up with an efficient manufacturing method.

[Purpose and structure]

The present invention relates to a method for manufacturing dynamic pressure group bearings, which have been suggested to have high bearing performance in conventional theoretical studies but could not be easily manufactured. It is an object of the present invention to provide a method for manufacturing a dynamic pressure group bearing that can be manufactured even if there is a problem, and the above object can be achieved by providing the method described in the claims. That is, in the present invention, a groove for generating dynamic pressure is provided in either one of a bearing and a journal that face each other, and relative motion 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 (a1 to (8)).

(a) A step in which at least one of the bearing and the journal is made of ceramic; Tb) At least one of the bearing and the journal is made of ceramic, and resin or rubber is formed on opposing surfaces of the ceramic member. (c) curing the printed paint; (d)
A step of performing shot blasting on the part of the surface where the paint is not printed to form grooves; (el) A step of removing the paint on the surface.

It is related to.

According to the present invention, the pattern of the grooves for generating dynamic pressure is formed by covering the lands around the grooves formed on the opposing surfaces of the ceramic member with paint and then sandblasting them. It is formed.

According to the present invention, the paint used for printing includes epoxy resin,
Resins such as urethane resin, unsaturated polyester resin, silicon resin, fluorine resin, polyimide resin, butadiene rubber, isoprene rubber, natural rubber, chloroprene rubber, acrylonitrile-butadiene copolymer rubber, acrylonitrile-chloroprene copolymer rubber, Acrylonitrile/isoprene copolymer rubber, urethane rubber.

It is preferable to use rubber such as urethane-epoxy copolymer rubber, fluororubber, silicone rubber, etc., and the viscosity is adjusted to a predetermined value depending on the type of printing method.

For example, when applying the screen printing method, it is important that the coating film is in a state that does not cause surface sagging and is easy to print. Viscosity 50-30000P
It is preferable to set it within the range of S.

Fillers such as glass beads, glass fibers, mica, and other ceramic powders may be added to the paint for the purpose of adjusting viscosity or improving wear resistance. It is also necessary to adjust the film thickness of the printed paint according to the operating conditions of shotblasting, and in particular when forming deep grooves using large particles, a thick resin layer is required. To prevent this, the layer of paint is thickened by roughening the mesh or printing multiple times.

The method for curing the paint is to use a paint to which a curing agent has been added in advance, and after printing, harden at room temperature.

A method of curing by heat curing, ultraviolet curing, etc., or a method of using a resin or rubber prepolymer as a coating material and then polymerizing and curing with a polymerizing agent after printing can be applied.

Further, according to the present invention, if foreign matter such as fine particles or oil is attached to the ceramic on which grooves for generating dynamic pressure are to be formed, an organic solvent, an alkaline aqueous solution, or Pretreatment of cleaning with an acidic aqueous solution, warm water, etc. can also be performed.

Note that in the present invention, a wide range of known printing methods can be applied as printing methods. The shape of the bearing surface is the fifth
Any printing method may be used as long as the surface is flat as shown in Figure (a), but the spiral pattern must be printed at a predetermined position on the bearing/surface. Also,
When the shape of the bearing surface is a cone or cylinder as shown in FIG. 5 [C], it is preferable to use screen printing. That is, by rotating the ceramic member on which the cylindrical or conical bearing surface is formed in synchronization with the movement of the screen on which the spiral pattern is formed, the spiral pattern can be accurately printed on the bearing surface.

Furthermore, as shown in Figure 5 (dl), pad printing is a simple method for creating a spiral pattern on a convex portion on a spherical surface.In other words, using an intaglio plate on which a spiral pattern of the desired shape has been formed in advance,
After coating the intaglio plate with paint using an ink coater, a doctor removes the paint other than the concave areas of the intaglio plate, then presses a pad against the intaglio plate to transfer the paint in the concave areas to the surface of the band, and then transfers the pad to the printing substrate. However, this is a method of forming a spiral groove pattern on the bearing surface by pressing it against the surface of the ceramic, and if the bearing surface is convex or concave, the pad will elastically deform freely according to the shape. Therefore, it can be said to be particularly suitable.

In addition, in shot blasting, Si, which has high hardness,
It is preferable to use C particles and AIICh particles, and the particle size should be selected from the range of 80 mesh to 1500 mesh. In other words, when forming deep grooves, if the paint film is thick and shot blasting is performed using large particles, grooves can be formed without unnecessarily prolonging the time required for shot blasting. In addition, when forming shallow or narrow grooves, the desired groove can be formed with a shot time that is easy to control by reducing the coating thickness and performing shot blasting using particles of small diameter.

[Effect]

According to the present invention, since ceramic, which is an extremely hard material, is selected as the member constituting the opposing surfaces on which the grooves for generating dynamic pressure are formed, even when a large dynamic pressure is generated, the dynamic pressure The initial ideal shape can be maintained for a long period of time without deforming or damaging the shape of the groove and the shape of the surface formed for generation.

Furthermore, in the present invention, when processing the grooves for generating dynamic pressure, paint is applied to the pattern of the grooves for generating dynamic pressure by printing on the bearing surface of the ceramic. Furthermore, a groove pattern of a desired shape for generating dynamic pressure is printed on the bearing surface, and the printed paint is easily removed from the bearing surface by mechanical vibration, etc. Does not peel off.

Next, the present invention will be explained by examples.

[Example 1] A planar spiral group bearing shown in FIG. 5cb) was manufactured according to the present invention as follows.

(1) Molding process After molding SiC fine powder (average particle size 0.15 μm) into a disk shape, the resulting formed body is fired at normal pressure and high temperature,
It was a disk with a diameter of 50+m and a thickness of 2 dragons. In addition, the surface of the disk (the surface on which the grooves for generating dynamic pressure are to be machined) was made smooth and flat with few undulations by ramp finishing. Note that the waviness of the entire surface was within ±1 μm.

(2) Pretreatment step The smooth SiC disk obtained in the above molding step was cleaned with trichloride, and then heated with 20 wt% NaO
It was degreased by immersing it in a H aqueous solution for 5 minutes.

After degreasing, wash with 60°C warm water for 5 minutes, then 10wt
The surface of the ceramic disk was made clean by neutralizing it with a %H, SO4 aqueous solution and then washing it with warm water at 60°C.

(3) Preparation and printing of paint A butyl cellosolve solvent was added to the urethane-epoxy ink, and the viscosity was adjusted to about 200 PS to prepare a paint for printing. Printing is done on the stainless steel screen 1 shown in Figure 1.
Screen printing was performed using 3. In Figure 1, 1
3 is a stainless steel screen, with black painted part 1
4 is a 200-mesh screen portion, and a white portion 15 is a non-porous portion. A spiral pattern 16 is formed by the screen portion 14 and the non-porous portion 15, and grooves for generating dynamic pressure are machined on the bearing surface corresponding to the non-porous portion 15.

Note that the outer peripheral edge of the stainless steel screen 13 on which the spiral pattern 16 is formed is a thick stainless steel frame 17.
A small hole 18 is formed in the frame 17 for positioning when setting the screen 13 on a printing jig (not shown).

First, a ceramic disk is placed in a printing jig with the bearing surface facing up, and then the screen 13 is set at a predetermined position in the printing jig. In this state, the screen 13 is placed on the bearing surface, so the wax coated with the viscosity-adjusted paint is swept over the screen 13, and the screen portion 14 of the spiral pattern 16 shown in FIG.
The paint was printed on the bearing surface located below all the black areas).

(4) Curing process The screen was removed from the printing jig, and then the ceramic disc was heated to 100° C. with the ceramic disc set therein and held for 10 minutes to dry and harden. The film thickness of the obtained paint is approximately 15μ
It was m.

(5) Grooving process Silicon carbide particles with an average particle diameter of 700 mesh are used to form an average groove depth on the surface of the disk 14 after the pattern forming process in which the smooth surface of the ceramic is covered with a spiral pattern resin layer. Shot blasting was performed so that the diameter was approximately 10 μm. The shot time at this time was 120 seconds.

(8) Film peeling step 5 (2) After spraying the tZNaOH aqueous solution for 2 minutes,
Brush to remove the paint adhering to the bearing surface.
Washed with warm water at 60°C for 5 minutes.

FIG. 2 is a chart showing the surface roughness of the surface of a ceramic disk into which grooves for generating dynamic pressure have been formed.

As is clear from Fig. 2, the portion 16 corresponding to the land
Because it was covered with a resin layer, it was not damaged by shot blasting, and its smooth surface was maintained, and the uneven patterns of land 16 and group 17 were also sharp.

- [Example 2] As a bellingbone bearing shown in FIG. 5(b), grooves in a herringbone pattern were processed on the circumferential surface of a ceramic (SiC dense sintered body) cylinder.

First, the surface roughness (Hffi, ) of the outer circumferential surface of a ceramic cylinder was made 1 μm or less by outer surface grinding, and the outer circumferential surface was cleaned by the same operation as in the pretreatment step.

FIG. 3 is a front view of the stainless steel screen 13 on which a herringbone pattern 19 is formed, and the screen portion 14
is a 200-mesh screen, which is shown in black. And the upper part 1 of this herringbone pattern
9a and the lower part 19b have a continuous pattern.

FIG. 4 is a schematic diagram when printing a herringbone-like groove pattern for generating dynamic pressure on the outer peripheral surface of a cylinder. The screen 13 in Figure 3 is attached to the upper part 19a or the lower part 19b.
Set it on the printing jig so that the pattern is facing forward, put the paint 22 prepared in the same way as in Example 1 on the top surface of the screen 13, and then set it on the cylinder 20,
Then, the screen 13 is moved in the direction of the arrow 23 by pressing the screen 13 against the cylinder 20 with the squeegee 21 from the side opposite to the cylinder 20, and at the same time, the screen 1
The cylinder 20 was rotated in the direction of the arrow 24 in synchronization with the moving speed of 3.

As the cylinder 20 rotates once, the position of the screen 13 moves from the upper part 19a of the herringbone pattern to the lower part 19b of the herringbone pattern in FIG. The paint adhered to the exposed areas, forming a continuous pattern around the entire circumference. Then, after drying and curing in the same manner as in Example 1,
Shot blasting was performed using approximately 700 meshes of SiC particles. The thickness of the cured resin at this time is approximately 15 μm.
During blasting, the nozzle was fixed, the cylinder 20 was rotated, and shot blasting was performed for 60 seconds to form a herringbone-shaped groove for generating dynamic pressure with a groove depth of approximately 8 μm.

In addition, to describe the embodiments of each of the above-mentioned steps in more detail, first, it is desirable that the ceramics used for the bearing in the forming step be of high strength and good thermal conductivity;
iC, 5izN4 is suitable. Further, it is desirable that the sintered ceramic has a dense structure. Furthermore, the surface on which the grooves for generating dynamic pressure are to be formed depends on the size of the surface and the conditions of use, but for example, in the case of a flat surface, the diameter is 1 μm.
The surface roughness is as follows and the waviness on the entire surface is ±5μ
It is desirable that the diameter is less than m, and it is also a curved surface (spherical surface).

In the case of a cylindrical surface (one conical surface, etc.), a surface roughness finished to ±1 μm should be used.

The pretreatment process can be changed as appropriate depending on the contamination status of the bearing surface, and it is also effective to use ultrasonic cleaning in combination with each of the above operations, or to add an ultrasonic cleaning operation separately. The film thickness of the paint should be determined by taking into consideration the conditions of shot blasting in the subsequent groove processing process, but it is important to consider that the particles used for shot blasting are small in size (for example, 1.
500 mesh), the film thickness may be thin; if particles with a large diameter (for example, 100 μm) are used, the film thickness may be O,
Since the thickness of L to Q is about 3 mm, it is necessary to repeat the coating process many times.

In addition, in the groove processing process, the particles used for shot blasting can be made of various substances such as silicon carbide, alumina, and silicon oxide, but when the groove depth is deep, large particles are used, and shallow When forming grooves, it is desirable to use particles of small diameter. The depth of the groove varies depending on the viscosity of the fluid interposed between the opposing surfaces.
Low viscosity fluid grooves should be shallow; in this case, the depth of the grooves can be easily changed by adjusting the shot blasting time.

〔effect〕

In the present invention, the member in which the groove for generating dynamic pressure of the dynamic pressure group bearing is formed is made of ceramics, so even when a large dynamic pressure is generated, the shape of the groove for generating dynamic pressure is deformed. Therefore, it is possible to manufacture a dynamic pressure group bearing that can appropriately generate dynamic pressure even in a high load region.

Furthermore, in the present invention, since the spiral pattern is printed on the bearing surface where the grooves for generating dynamic pressure are to be formed by a known printing method such as screen printing or pad printing, it is possible to form an accurate shape on the bearing surface. It is possible to form a spiral pattern, which is particularly advantageous when a spiral pattern with a complicated shape or a spiral pattern formed by thin lines is used as a pattern of grooves for generating dynamic pressure. Furthermore, in the present invention, the paint printed on the bearing surface does not easily fall off during normal operations such as mechanical vibration, and the printed bearing surface can be reliably protected even during shot blasting. , it is possible to accurately form grooves for generating dynamic pressure in a desired spiral pattern on the bearing surface.

Furthermore, in the present invention, even if the shape of the bearing surface is not only flat but also various shapes such as 3 spherical surfaces, 3 cones, 1 cylinder, etc., the groove pattern for generating dynamic pressure can be easily formed by printing. Furthermore, the depth of the grooves for generating dynamic pressure can be easily adjusted depending on the shot blasting conditions, and by simply changing the shot blasting time, a spiral pattern of the desired depth can be processed into the ceramic bearing member. be able to.

The dynamic pressure group bearing obtained in this way is not only capable of effectively generating dynamic pressure even under large loads, but also has corrosion resistance and resistance because the bearing surface is formed on a ceramic member. It has the advantage of good abrasion resistance.

[Brief explanation of drawings]

Fig. 1 is a front view of a screen used for carrying out the present invention, Fig. 2 is a chart showing the surface roughness of ceramics used for carrying out the present invention, and Fig. 3 is a front view of a screen used for carrying out the present invention. Figure 4 is a schematic diagram showing an embodiment of the present invention, Figure 5(a)
5 is a partially fragmented longitudinal cross-sectional view of a planar spiral group bearing, and FIGS.

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 relative motion is achieved with a fluid interposed in a minute gap between the bearing and the journal. A method for manufacturing a hydrodynamic group bearing, which comprises the following sequence of steps (a) to (e). (a) manufacturing at least one of the bearing and the journal from ceramics; (b) manufacturing resin or rubber on opposing surfaces of either the bearing or the journal and a ceramic member; (c) a step of curing the printed paint; (d) a step of performing shot blasting on the part of the surface where the paint is not printed to form grooves; (e) removing paint on the surface; 2. The member provided with the groove is made of silicon carbide, silicon nitride,
The method according to claim 1, wherein at least one selected from zirconia, alumina, mullite, and sialon is used. 3. The viscosity of the paint used for printing is 50 to 30,000P.
The method according to claim 1, characterized in that the range is S. 4. The resin is an epoxy resin, a urethane resin, an unsaturated polyester resin, a silicon resin, a fluorine resin,
2. The method according to claim 1, wherein at least one selected from polyimide resins is used. 5. The above rubbers include butadiene rubber, isoprene rubber, natural rubber, chloroprene rubber, acrylonitrile-butadiene copolymer rubber, acrylonitrile-chloroprene copolymer rubber, acrylonitrile-isoprene copolymer rubber, urethane rubber, urethane-epoxy copolymer rubber, and fluororubber. 2. The method according to claim 1, wherein the rubber is at least one selected from , silicone rubber.