JPS62266216A - Ceramics bearing and its production - Google Patents

Abstract

PURPOSE:To improve the performance and facilitate the production by combining an inside member made of ceramics and calcined in a projected or recessed cross section shape on its periphery and an outside member made of ceramics and having a corresponding inner shape and the minimum diameter which is larger than the maximum diameter of the inside member and calcining and shrinking them. CONSTITUTION:An inside member 1 made of ceramics and having a shape formed by rotating a V-shaped recessed cross section around an axis A is molded and calcined, and its surface is polished. The raw material 2A of an outside member 2 having a circular inner shape corresponding to the V-shaped recess of the inside member 1 is molded with ceramics powder. The minimum diameter d0 of the raw material 2A is made larger than the maximum diameter D1 of the inside member 1, and they are combined and calcined, then the minimum diameter D0 of the outside member 2 becomes smaller than the maximum diameter D1 of the inside member 1. Accordingly, a bearing excellent in durability, chemical resistance, acid resistance and heat resistance can be easily produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sliding bearing made of ceramics. The present invention also includes a method of manufacturing such a ceramic bearing.

[Conventional technology] New ceramic materials that have become available as fine ceramic technology has advanced in recent years have the characteristics of conventional ceramics, such as heat resistance and chemical resistance.
Taking advantage of its wear resistance and low coefficient of friction, it is used for things such as skid rails in heating furnaces.

On the other hand, as various industrial and consumer machines become smaller and more sophisticated, the bearings that support rotating shafts are required to be smaller and lighter, and to withstand high loads and high rotations. Efforts are being made to meet this demand through improvements in special steel used as bearing materials and advances in processing technology, but the results are still not fully satisfactory.

[Problems to be Solved by the Invention] The purpose of the present invention is to take the current state of the art as described above one step further and provide a bearing that is made of ceramic and has superior performance than conventional steel bearings. It is in. It is also an object of the present invention to provide a method for manufacturing such a ceramic bearing.

Structure of the Invention [Means for Solving Problems 1] Describing with reference to the drawings, the ceramic bearing of the present invention has an outwardly convex or concave cross section, in the illustrated example a V-shaped concave cross section. An inner member 1 made of ceramics having a shape obtained by rotating around the axis A, and surrounding it a curved line in the illustrated example, which corresponds to the outer shape of the inner member 1.
It also consists of an inner part 2 made of ceramics having an inner surface shape obtained by rotating a part of an approximately circular arc, and the maximum diameter DI of the inner member is the minimum diameter of the outer member. It is characterized by being larger.

The maximum diameter DI of the inner member and the minimum diameter of the outer member.

It is sufficient that the difference between the two is at least a limit that allows both to withstand the thrust in the axial direction and maintain the structure as a bearing.

Usually, at least 2μ is sufficient, and 10μ or more is safe.

Although this ceramic bearing generally does not require lubrication, it may of course be lubricated depending on the application, and in preparation for this, it is preferable to provide a lubrication hole 5 in the outer member as shown in FIG.

The ceramic bearing of the present invention may have various embodiments.

For example, in the example shown in FIG. 1, the outer surface of the inner member is concave and the inner surface of the outer member is convex, but as shown in FIG. 2, the relationship may be reversed. Also, the shaft 3 is also the same as the example shown in FIG.

is made of a different material than the inner member, such as steel,
They are integrated using methods such as press fitting, cold fitting, and gluing.
As shown in FIG. 2, the inner member 1 and the shaft 3 can also be integrally formed.

As shown in FIG. 3, the method for manufacturing a ceramic bearing of the present invention is to obtain a shape obtained by rotating an outwardly convex or concave cross section, in the illustrated example, a V-shaped concave cross section, around an axis A. An inner member made of ceramic is prepared, and its periphery has an inner surface shape corresponding to the outer surface shape of the inner member, but a minimum diameter d. is larger than the maximum diameter DI of the inner member, and is surrounded by a material 2A that forms ceramics by firing, such as a powder formed with a binder, and is sintered by holding the whole at a required temperature for a required time to form the material of the outer member. 2A is made of ceramic, and its minimum diameter is smaller than the maximum diameter of the inner member, as shown in FIG. Ceramics include alumina,
Zirconia, silicon nitride, and other fine ceramics are suitable, and may be selected depending on the intended use of the bearing product.

Preferably, the outer surface of the inner member is ground to core and smooth.

[Function 1] Since the formation of ceramics by sintering is accompanied by shrinkage, the minimum diameter of the material 2A of the outer member becomes smaller and easily becomes smaller than the maximum diameter of the inner member. As a result, the two members, the inner and outer parts, no longer move backward in the axial direction. As long as the degree of contraction is kept at a limit where the outer member tightens the inner member, rotation is possible.

The smooth surfaces of well-hardened, dense ceramics have surprisingly low coefficients of friction, and exhibit high performance as bearings. Therefore, although it is a type of sliding bearing, it can also be used as a thrust bearing or a radial bearing. Needless to say, it has excellent wear resistance, so it can withstand long-term use.

[Example] An inner member having the shape shown in FIG. 3 and having a maximum diameter D1 of 7 g was manufactured by molding and sintering alumina powder, and its surface was polished.

The same alumina powder was molded to prepare a material having the shape shown in FIG. 3 and having a minimum diameter d□=4 m.

A ceramic bearing having the cross-sectional shape shown in FIG. 4 was obtained by putting the inner member 1 into the material 2A in a furnace and sintering it. The shrinkage due to sintering of the material is approximately 22% in terms of the degree of reduction in the outer diameter.

Press-fit a lit shaft into this ceramic bearing,
With the outer member fixed and a load of 3009 applied to the bearing, rotate one end of the shaft at a rotational speed of approximately 6000 rl)
It was driven by m. The bearing maintained its performance even after 210 consecutive days of use. For comparison, a steel miniature bearing of approximately the same size tested under the same conditions was 1
After 50 days of operation, it wore out and lost its functionality.

Effects of the Invention The ceramic bearing of the present invention has significantly higher durability than the conventional III bearing. Therefore, it is suitable for equipment that requires continuous operation over a long period of time, and for applications where maintenance is difficult. It also has properties unique to ceramics, such as chemical resistance, acid resistance, and salt water resistance, making it useful for various chemical plants and ships. It goes without saying that it is heat resistant, so it is useful as a bearing used at temperatures where lubricating oil cannot be used, or at even higher temperatures. The advantage of low wear means that it can also be used in applications such as casters used in clean rooms for IC manufacturing, for example.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are both sectional views showing examples of the ceramic bearing of the present invention. 3 and 4 are schematic cross-sectional views for explaining the method of manufacturing a ceramic bearing of the present invention, and FIG.
The figure shows the state before sintering, and FIG. 4 shows the state after sintering. 1...Inner member 2...Outer member 2A...Outer member material 3...
・Shaft Dl...Maximum diameter Do of inner member...Minimum diameter do of outer member...Minimum diameter of material Patent applicant Hisashi Kobayashi Daido Shinji Niho

Claims (6)

[Claims] (1) An inner member made of ceramics having a shape obtained by rotating an outwardly convex or concave cross section around an axis;
A ceramic bearing comprising a ceramic outer member surrounding the inner member and having an inner surface shape corresponding to the outer surface shape of the inner member, the inner member having a maximum diameter larger than a minimum diameter of the outer member. (2) The difference between the maximum diameter of the inner member and the minimum diameter of the outer member is 2
The ceramic bearing according to claim 1, which has a diameter of μ or more. (3) The ceramic bearing according to claim 1, wherein the outer member is provided with a radial oiling hole. (4) The ceramic bearing according to claim 1, wherein the ceramic is selected from alumina, zirconia, silicon nitride, and other fine ceramics. (5) A ceramic inner member having a shape obtained by rotating an outwardly convex or concave cross section around an axis is prepared, and the periphery thereof has an inner surface shape corresponding to the outer surface shape of the inner member. has a minimum diameter greater than the maximum diameter of the inner member,
A method for manufacturing a ceramic bearing, characterized in that the outer member is surrounded by a material that forms ceramics by firing, the outer member is made of ceramic by firing, and the minimum diameter of the outer member is made smaller than the maximum diameter of the inner member. (6) The method for manufacturing a ceramic bearing according to claim 5, which is carried out by polishing the surface of the inner member in advance.