JPS6340969B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a solid lubricated ceramic bearing for use in watches and precision instruments, which has a selenide metal phase on its surface, and a method for manufacturing the same. Conventional bearing materials for watches and precision instruments generally use hard stone or metal, and lubrication is required between the shaft and the bearing. This lubrication reduces the coefficient of friction between the shaft and bearing and prevents wear in this part, but it requires periodic replenishment of volatile oil, and chemical alteration of the oil can reduce torque transmission efficiency. If the concentration decreases, there is a drawback that the watch or other equipment must be disassembled for cleaning. FIG. 1 is a cross-sectional view showing a conventional watch bearing that requires lubrication, where 1 is a ruby bearing for a watch, 2 is a gear shaft, and 3 is a recessed portion that is an oil sump. Generally, synthetic resin or composites of graphite, molybdenum disulfide, tungsten selenide, etc.
In oil-free bearings, the strength of the bearing material is low, so distortion occurs when transmitting high torque, which significantly deteriorates the transmission effect. There are also restrictions on use at high temperatures. The purpose of the present invention is to reduce the friction coefficient of the bearing, improve the wear resistance of the shaft and bearing, and increase the efficiency of transmitted torque by providing a selenized metal phase on the surface of the ceramic bearing. It is. Another object of the present invention is to eliminate oil reservoirs and oil grooves provided in bearings by eliminating oil lubrication, thereby reducing bearing processing costs and eliminating the drawbacks of conventional bearings. By using ceramic as the base of the bearing material and providing a selenide metal phase on its surface, it has excellent wear resistance.
The present invention provides a solid lubricated bearing that can withstand use in high and low temperature environments, can also be used in a vacuum atmosphere, and has high torque transmission efficiency.
The gist of this paper is to manufacture ceramic-metal selenide composite bearings by creating a composite of ceramic and metal in advance and subjecting it to selenization. It is characterized in that the metal phase is a selenium metal phase. FIG. 2 shows the manufacturing process of an alumina ceramic WSe ₂ solid lubricated bearing according to an embodiment of the present invention.
Alumina ceramic raw materials (Al ₂ O ₃ , MgO, SiO ₂ ,
CaO mixture) and tungsten powder were weighed with a tungsten content ranging from 1% to 40% by volume, and PVA was used as a binder for press molding.
(polyvinyl alcohol) and mix and grind in a ball mill to form a slurry. In order to make granules for powder molding from this slurry, granules of 80 to 100 microns are formed using a spray dryer, and in the powder molding process, they are shaped into a predetermined shape using a hydraulic press at a molding pressure of 2 to 6 tons/square glue. Obtain a molded product with Molded products have a dew point of +10 to +40 to remove the molding binder.
Primary firing is performed at 600°C for 2 hours in a wet hydrogen atmosphere at 600°C. When the secondary firing is carried out at 1600°C for 1 hour in hydrogen at a dew point of -20°C or lower or in a vacuum at 10 ^-3 torr or lower, a composite sintered body of alumina ceramic-W is obtained. This sintered body is polished to obtain a predetermined shape. The process from weighing the raw materials up to this point is step 4 of preparing a bearing made of ceramic containing metal that can reduce the coefficient of friction when it becomes selenide. Selenization treatment step 5 is carried out at 600°C to 700°C in a SeH ₂ −H ₂ −NH ₃ mixture.
By processing for 2 hours at
_Two phases of WSe can be obtained over a depth of 50μ. Table 1 below shows the raw material composition of Alumina Ceramic-W.

[Table] A sectional view of the solid lubricated bearing thus obtained in this example is shown in FIG. In Fig. 3, 6 indicates a cylindrical solid lubricated bearing with a circular hole, the external dimensions are 2.2ψ ( ^+0.006 ₊₀ ) mm, and the surface roughness is 1.5-
S, the dimensions of the circular hole 6a are 1.4 φ ( ^+0.006 ₊₀ ) mm, the surface roughness is 0.1-S, the thickness is 0.6 mm, and the thickness of the layer containing tungsten selenide is about 50 microns. The shaft 7 is a known one, and the material is SK4-F hardened steel heat-treated to Hu720, and the surface roughness is
0.1-S. The dimensions are shaft diameter 1.4φ ( ^-0.006 _-0.012 ) mm. In this way, metals that can be composited with alumina ceramic and have a low coefficient of friction value by selenizing the composite metal include Mo, Mo,
V, Nb, Ta, Ti, Zr, Hf, Re, Th, U, Te
etc., and all of them were able to be made into good oil-free bearings. In addition, ceramics combined with these metals are
In addition to alumina ceramics, glasses that can withstand selenization treatment are also effective as solid lubricated bearings of the present invention. That is, as a method for obtaining a predetermined bearing shape, in addition to the powder molding method, the doctor blade method can be used, and press punching from a green sheet can also be used. Table 2 shows the friction coefficient measurement results measured using a T-type pendulum friction tester.

[Table] With the above configuration, the friction coefficient is lower than that of conventional ceramic bearings, it is also more wear resistant, the shaft torque transmission efficiency is good, and there is no need for an oil sump.
It has a simple shape and can be made thinner, and costs and man-hours are significantly reduced, and the practical effects are great.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional bearing, Fig. 2 is a process diagram of a manufacturing procedure of a solid lubricated bearing showing an embodiment of the present invention, and Fig. 3 is a sectional view of a bearing which is an embodiment of the present invention. . 6... Solid lubricated bearing, 6b... Selenide, 4
...Process of preparing a bearing made of ceramic containing a metal that can reduce the coefficient of friction when it becomes selenide, 5...Selenization treatment step.

Claims (1)

[Scope of Claims] 1. A bearing made of ceramic, which contains a metal whose coefficient of friction decreases due to selenization,
Mo, W, V, Nb, Ta, Ti, Zr, Hf, Re, Th,
A solid lubricated bearing containing one or more of the group consisting of U and Te, and having a selenide phase of the metal on the surface of the bearing. 2. The solid lubricated bearing according to claim 1, wherein the bearing consists of only a flat surface and a cylindrical surface. 3 Metals whose coefficient of friction decreases due to selenization,
Mo, W, V, Nb, Ta, Ti, Zr, Hf, Re, Th,
A method for producing a solid lubricated bearing comprising the steps of: preparing a bearing made of ceramic containing one or more of the group consisting of U, and forming a selenide phase on the surface of the bearing by selenizing the bearing.