JPH03255224A - Bearing for vacuum use - Google Patents

Abstract

PURPOSE:To reduce wear by making rolling bodies out of a specific ceramics, and race-way rings out of a specific ceramics or stainless steel, and also coating of molybdenum disulfide is applied to both of them, and by forming retainers out of polytetrafluoroethylene. CONSTITUTION:Race-way rings comprise an inner ring 1 and an outer ring 2, and they are made of stainless steel having solid lubricating coatings 3a, 3b respectively, which have been formed by applying the spatter-coating of molybdenum disulfide. Rolling bodies 4 are made of ceramics of silicon carbide or of silicon nitride, and have the same kind of solid lubricating coating 5 as the raceway rings. Retainers 6 are formed out of polytetrafluoroethylene. Accordingly, wear can be reduced, and lifetime can be prolonged.

Description

[Detailed Description of the Invention] [Industrial Application Fields] This invention is applicable to equipment mounted on artificial satellites, semiconductor manufacturing equipment,
It also relates to vacuum bearings used under conditions where oil or grease cannot lubricate them, such as bearings in medical X-ray tubes.

[Conventional technology] Conventional vacuum bearings are shown in FIGS. 4 and 5.

FIG. 4 is an external view of the vacuum bearing, and FIG. 5 is a sectional view.

In FIG. 5, 7 is an inner ring as a bearing ring, 3a is a solid lubricant coating applied to the surface of the inner ring 7 by sputter coating of molybdenum disulfide (M o S 2),
8 is an outer ring as a raceway ring, 3b is a solid lubricant coating applied to the surface of the outer ring 8 by sputter coating of molybdenum disulfide, and 9 revolves around its axis between the inner @ 7 and the outer @ 8. 5 is a solid lubricant coating applied to the surface of the rolling element 9 by sputter coating of molybdenum disulfide, and 6 is a cage for holding the rolling element 9. Above inner ring 7. Outer ring 8. The material of the rolling elements 9 is stainless steel (SUS440C).

Next, the effect will be explained.

Inner circle 7. For smooth movement of the outer ring 8 and rolling elements 9,
Solid lubricant coatings 3a, 3b, 5 are applied by sputter coating of molybdenum disulfide, and rolling elements 9 and cage 6 are applied.
For smooth sliding, the retainer 6 is made of low-friction polytetrafluoroethylene.

[Problems to be Solved by the Invention] However, with the materials of each component of conventional vacuum bearings, the solid lubricant coating formed by sputter coating of molybdenum disulfide tends to wear out quickly, shortening the life of the bearing. was there.

This invention was made to solve the above-mentioned problems, and aims to provide a bearing whose solid lubricant coating is less likely to wear out and which has a long life.

[Means for Solving the Problems] The vacuum bearing of the present invention comprises rolling elements made of silicon carbide or silicon nitride ceramics and having a surface sputter coated with molybdenum disulfide, and silicon carbide or silicon nitride ceramics. It consists of a raceway ring made of ceramic or stainless steel whose surface is sputter-coated with molybdenum disulfide, and a cage made of polytetrafluoroethylene.

[Function] In the vacuum bearing according to the present invention, the rolling elements are made of ceramics such as silicon carbide or silicon nitride, so that the life of the solid lubricant coating is extended. Furthermore, the life of the solid lubricant coating can be extended by using the rolling elements and a bearing ring made of silicon carbide or silicon nitride ceramics.

[Embodiments of the Invention] The present invention will be described below with reference to FIGS. 1 to 3. Components that are the same as those in the conventional example shown in FIG. 5 are designated by the same reference numerals, and their explanation will be omitted.

In Fig. 1, 1 is an inner ring as a bearing ring, 3a is a solid lubricant coating applied to the surface of the inner part 1 by sputter coating of molybdenum disulfide (MoS2), 2 is an outer ring as a bearing ring, and 3b is an outer ring as a bearing ring. 4 is a solid lubricant coating applied to the surface of the outer ring 2 by sputter coating of molybdenum disulfide, 4 is a rolling element that revolves between the inner ring 1 and the outer ring 2 while rotating, and 5 is a spun taco made of molybdenum disulfide. A solid lubricant coating 6 is applied to the surface of the rolling element 4 by a coating process, and numeral 6 is a retainer that holds the rolling element 4.

In the first embodiment of the present invention, the rolling elements 4 are made of silicon carbide or silicon nitride ceramics to extend the life of the solid lubricant coating.

Figure 2 shows a load of 9.8N in a vacuum of 10-'Pa or less.
, speed 0.6 m/s, stainless steel (S) under conditions of room temperature.
Lifespan of each material (stainless steel, silicon carbide, silicon nitride) coated with molybdenum disulfide sputter coating when the mating material is US440C (in this example, the material of the inner ring 1 and outer ring 2). This is experimental data showing. The figure shows that if the material of the inner ring 1 and outer ring 2 is stainless steel, the life of the solid lubricant coating will be longer if the rolling elements 4 are made of silicon carbide or silicon nitride ceramics than if they are made of stainless steel. , it can be seen that the life of each component becomes longer.

Further, in the second embodiment of the present invention, the inner ring 1. All of the outer ring 2° rolling elements 4 are made of silicon carbide or silicon nitride ceramics to extend the life of the solid lubricant coating. FIG. 3 shows the life span of a material sputter-coated with molybdenum disulfide when silicon nitride (s 13 N4 ) is used as a mating material under the same conditions as the experimental data shown in FIG.

According to the same figure, rolling elements 4. If both raceway rings (inner ring 1 and outer ring 2) are made of silicon carbide or silicon nitride ceramics, the life of the solid lubricant coating on each component will be longer than if either one is made of stainless steel. It can be seen that the life of the parts becomes longer.

In the above embodiments, the case of a ball bearing has been described, but the present invention can also be applied to a roller bearing, and can be applied to both a radial bearing and a thrust bearing.

[Effects of the Invention] As explained above, according to the vacuum bearing of the present invention,
A rolling element made of silicon carbide or silicon nitride ceramics with a sputter coating of molybdenum disulfide on the surface, and a rolling element made of silicon carbide or silicon nitride ceramics or stainless steel with a sputter coating of molybdenum disulfide on the surface. Since the bearing ring is composed of a bearing ring made of aluminum alloy and a cage made of polytetrafluoroethylene, the sputter-coated solid lubricant coating is hard to wear, and a vacuum bearing with a long life can be obtained.

[Brief explanation of drawings]

Figure 1 is a sectional view of the vacuum bearing of the present invention, Figures 2 and 3 are
The figures are respectively shown in the first part of the present invention. 4 and 5 show an example of a conventional vacuum bearing, FIG. 4 is an external view, and FIG. 5 is a sectional view. 1... Inner ring (raceway ring), 2... Outer ring (raceway ring), 3
a, 3b, 5...Solid lubricant film by sputter coating of molybdenum disulfide, 4...Rolling element, 6...
retainer.

Claims (1)

[Claims] A rolling element made of silicon carbide or silicon nitride ceramics and having its surface sputter coated with molybdenum disulfide, and silicon carbide or silicon nitride ceramics or stainless steel,
A vacuum bearing comprising a bearing ring whose surface is sputter-coated with molybdenum disulfide and a cage made of polytetrafluoroethylene.