JPH0132372B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Purpose of the invention [Field of industrial application] This invention relates to solid lubrication technology for high-temperature ceramic rolling bearings. [Prior Art] Ceramics have greater high-temperature strength than metal materials, so it can be said that their material properties can only be utilized when they are used in a high-temperature range. For these reasons, it has recently been considered that rolling bearings used in high-temperature regions be made of ceramics. However, when ceramics are applied to rolling bearings, lubrication becomes a problem. In other words, conventional high-temperature lubricating oils and greases cannot be used in the temperature range of 350°C or higher. Therefore,
A solid lubricant will be used for lubrication in this area. A commonly used solid lubrication method for rolling bearings is a method using solid lubricant transfer. As shown in FIGS. 8 and 9, this transfer method is applied to a rolling bearing 21 consisting of a bearing ring (inner ring 22, outer ring 23), cage 24, and rolling elements (balls 25 or rollers 26). , the bearing rings 22, 23 and the rolling elements 25, 26 are made of ceramics, and the retainer 24 is made of solid lubricant. During rolling, the solid lubricant is transferred from the cage 24 to the surfaces of the rolling elements 25 and 26, and the bearing rings 22,
It is transferred to the orbital surface of 23. In this way, the solid lubricant is supplied to the rolling surfaces and lubrication continues. [Problems to be Solved by the Invention] However, in conventional high-temperature solid lubricated rolling bearings configured as described above, the solid lubricant does not necessarily transfer well to the lubricated surface, and the rolling bearings in high-temperature environments has a short lifespan, and especially in environments of 500°C or higher, it is more difficult to transfer due to the formation of oxide films on lubricated surfaces. This invention was made in view of the above-mentioned circumstances, and provides a ceramic rolling bearing that can transfer solid lubricant well even in high-temperature environments and can be used in environments of 500°C or higher in the atmosphere. The purpose is to provide (B) Structure of the Invention [Means for Solving the Problems] In order to achieve this purpose, the high temperature ceramic rolling bearing of the present invention includes a cage made of a ceramic raceway, a rolling element, and a solid lubricant. and one or both of the raceway surface of the ceramic raceway ring and the surface of the rolling elements are coated with a metal that has better adhesion properties for the solid lubricant than the ceramics. It is a feature. Hereinafter, details of the present invention will be explained with reference to the drawings showing one embodiment. In FIG. 1, 1a is a radial ball bearing, and the radial ball bearing 1a is composed of a raceway consisting of an inner ring 2 and an outer ring 3, a cage 4, and rolling elements of balls 5 held in the cage 4. It's summery. The bodies of the inner ring 2 and outer ring 3 are each made of ceramics such as silicon nitride (Si ₃ N ₄ ), and the raceway surface 7 on which the balls 5 roll is covered with a metal coating 8.
The metal coating 8 is formed by depositing a metal such as (Fe) or chromium (Cr) by sputtering, ion plating, vapor deposition, or the like. The main body of the cage 4 is made of ceramics such as silicon nitride (Si ₃ N ₄ ), and the surface is coated with a solid lubricant such as molybdenum disulfide, tungsten disulfide, or graphite, or the entire cage 4 is made of ceramic such as silicon nitride (Si 3 N 4 ). Consists of solid lubricant. The ball 5 has a main body made of ceramics such as silicon nitride (Si ₃ N ₄ ), and a surface made of iron (Fe),
It is covered with a metal coating 11 formed of metal such as chromium (Cr) by a method such as sputtering, ion plating, or vapor deposition. FIG. 2 shows a radial roller bearing 1b according to another embodiment of the invention. In this radial roller bearing 1b, rollers 6 are used as rolling elements. The main bodies of the inner ring 2 and outer ring 3 are made of ceramics, and the raceway surface 7 on which the rollers 6 roll is covered with a metal coating 8. The cage 4 has a main body made of ceramics, the surface of which is coated with a solid lubricant,
Alternatively, the entire cage 4 is made of solid lubricant. The main body of the roller 6 is made of ceramics, and its surface is coated with a metal coating 11. FIG. 3 shows a thrust ball bearing 1c according to another embodiment of the invention. Balls 5 are used as rolling elements in this thrust ball bearing 1c. The main bodies of the thrust piece 13 and the base plate 14 are made of ceramics, and the raceway surface 7 on which the balls 5 roll is covered with a metal coating 8. The main body of the cage 4 is made of ceramics, and the surface thereof is coated with a solid lubricant, or the cage 4 is entirely made of a solid lubricant. The main body of the ball 5 is made of ceramics, and its surface is coated with a metal coating 11. FIG. 4 shows a thrust roller bearing 1d according to another embodiment of the invention. In this thrust roller bearing 1d, rollers 6 are used as rolling elements. The main bodies of the thrust piece 13 and the base plate 14 are made of ceramics, and the raceway surface 7 on which the rollers 6 roll is covered with a metal coating 8. The main body of the cage 4 is made of ceramics, and the surface thereof is coated with a solid lubricant, or the cage 4 is entirely made of a solid lubricant. The main body of the roller 6 is made of ceramics, and its surface is coated with a metal coating 11. [Function] In the rolling bearing configured in this way,
When the rolling elements (balls 5, rollers 6) roll, the solid lubricant is easily transferred from the surface of the cage 4 to the metal coating 8 on the surface of the rolling elements. Furthermore, the solid lubricant adhering to the surface of the rolling elements easily transfers to the metal coating 8 on the raceway surface 7 of the raceway rings (inner ring 2, outer ring 3) on which the rolling elements roll, thus preventing the solid lubricant from transferring. The fitting is completed, and the supply of solid lubricant to the rolling surfaces of the raceway ring and the rolling elements continues.

【table】

[Table] Test results (1) Roughness of the rolling surface of the base plate 14 when thrust ball bearing A was operated for 250 hours (Fig. 6A) and base plate when thrust ball bearing B was operated for 25 hours. As is clear from the comparison with the roughness of the raceway of No. 14 (Fig. 6B), the damage to the raceway of thrust ball bearing A is more than 10 times longer than that of conventional thrust ball bearing B. It turns out that there are few. (2) Figure 7 is an X-ray photograph of the surface of the ball. Figures 7a and 7b show thrust ball bearing A of this invention.
Figure 7a shows the distribution of Cr as measured by an X-ray microanalyzer, and Figure 7b shows the distribution of Si as measured by the X-ray microanalyzer. Figures 7c and d show thrust ball bearing A of this invention.
Figure 7c shows the distribution of C as measured by an X-ray microanalyzer, and Figure 7d shows the distribution of Fe as measured by the X-ray microanalyzer. Figures 7e and 7f are X-ray photographs of the surface of the balls of conventional thrust ball bearing B, of which Figure 7e shows the distribution of C measured by an X-ray microanalyzer, and Figure 7f shows the X-ray micrograph. by analyzer
This shows the distribution of Fe. In this way, there is no Fe on the surface of the balls of the conventional thrust ball bearing B, and therefore almost no graphite has been transferred to the cage, but Cr (Cr) is present on the surface of the balls of the ball bearing A of the present invention. Fig. 7a) and iron (Fig. 7d) are present, indicating the transfer of graphite (Fig. 7c), which is the cause of the long life of rolling bearings. It is becoming. (c) Effects of the Invention As is clear from the above explanation, according to the present invention, solid lubricant transfer is performed well even in high-temperature environments, and the ceramic rolling material can be used in environments of 500°C or higher in the atmosphere. You can get bearings.

[Brief explanation of drawings]

FIG. 1 is an explanatory longitudinal cross-sectional view showing a radial ball bearing according to one embodiment of the present invention, FIG. 2 is an explanatory longitudinal cross-sectional view showing a radial roller bearing according to another embodiment of the invention, and FIG. FIG. 4 is a vertical cross-sectional explanatory diagram showing a thrust ball bearing according to another embodiment of the invention, FIG. 4 is a vertical cross-sectional explanatory diagram showing a thrust roller bearing according to another embodiment of the invention, and FIG. Figure 6 is a graph showing the surface roughness of the raceway surface of the base plate of a thrust ball bearing, Figure 7 is an X-ray photograph of the surface of the balls of a thrust ball bearing, and Figure 8 is an explanatory diagram of a vertical cross section showing a ball bearing. FIG. 9 is an explanatory vertical cross-sectional view showing a conventional radial ball bearing, and FIG. 9 is an explanatory vertical cross-sectional view showing a conventional radial roller bearing. 1... Radial ball bearing, 2... Inner ring, 3... Outer ring, 4... Cage, 5... Ball, 6... Roller, 7...
...Race surface, 8...Metal coating, 11...Metal coating,
13... Thrust piece, 14... Base plate, 21...
Rolling bearing, 22... Inner ring, 23... Outer ring, 24
...Cage, 25...balls, 26...rollers.

Claims (1)

[Claims] 1. The cage has a cage made of a ceramic bearing ring, rolling elements, and a solid lubricant, and a metal having better transferability of the solid lubricant than the ceramic is used on the raceway surface and the rolling element of the ceramic bearing ring. A high-temperature ceramic rolling bearing characterized in that one or both surfaces of a moving body are coated.