JPH10231842A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent oxidation of graphite and to prevent lowering of strength of a holder by forming at least a rolling element of ceramics and dispersing and containing boron the graphite of the holder. SOLUTION: This rolling bearing is constituted of an inner ring 1, a ball 3 arranged between the inner and outer rings 1, 2 and a holder 4 to hold the ball 3, the ball 3 is formed of ceramics, and the holder 4 is formed of graphite. Additionally, boron is dispersed and contained in the graphite of the holder 4. Consequently, in case of using this ball bearing in a high temperature state of more than 500 deg.C, the boron contained in the holer 4 is combined with oxygen and becomes boric oxide, and consequently, the surface of the holder 4 is coated with boric oxide, and oxidation of the graphite is prevented. Additionally, as the ball 3 is formed of ceramics, coating of boric oxide on an inner surface of a pocket 5 of the holder 4 is abrased and the graphite is exposed, and lubricating performance of the bearing is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing, and more particularly to a rolling bearing applicable to a high temperature state.

[0002]

2. Description of the Related Art Conventionally, when a rolling bearing having an inner ring, an outer ring, a rolling element disposed between the inner and outer rings, and a retainer for holding the rolling element is used at a high temperature of, for example, 300 ° C. or more,
Since grease or oil cannot be used as a lubricant, cages were manufactured using graphite as a solid lubricant, and lubrication of bearings was performed using transfer of graphite from the cage to rolling elements. .

[0003]

However, in recent years,
Further, a rolling bearing may be used at a high temperature of, for example, 500 ° C. or higher. However, if a cage is formed only of graphite as in a conventional bearing, a problem of oxidation occurs in graphite and strength is reduced. Therefore, there is a problem that a graphite cage cannot be used.

Accordingly, an object of the present invention is to prevent graphite from being oxidized and to prevent the strength of a graphite retainer from being reduced.

[0005]

As a means for solving the above problems, a rolling bearing having an inner ring, an outer ring, a rolling element disposed between the inner and outer rings, and a graphite retainer for holding the rolling element. Wherein at least the rolling elements are formed of ceramics, and boron is dispersed and contained in the graphite of the cage.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a ball bearing according to an embodiment of the present invention, which includes an inner ring 1 and an outer ring 2.
And a ball 3 disposed between the inner and outer rings 1 and 2 and a retainer 4 for holding the ball 3. The ball 3 is formed of ceramics, and the retainer 4 is formed of graphite.

The graphite of the retainer 4 includes:
Boron is dispersed and contained. 1 wt% boron
% Or more. The ball bearing employing this cage 4 is
When used in a high temperature state of 00 ° C. or more, boron contained in the retainer 4 combines with oxygen to form boron oxide,
As a result, the surface of the cage 4 is coated with the boron oxide 6 as shown in FIG. 2, and the graphite of the cage 4 is prevented from being oxidized. This is well understood in the oxidation test results of FIG. That is, FIG. 3 shows the results of an oxidation test of graphite A containing no boron and graphite B containing boron at a high temperature in the air (600 ° C. in FIG. 3). In FIG. 3, graphite B1 indicates a graphite material containing 1 wt% of boron, graphite B3 indicates a graphite material containing 3 wt% of boron, and graphite B10
Indicates a graphite material containing 10 wt% of boron. As can be seen from FIG. 3, it can be seen that oxidation can be effectively prevented by adding boron to the graphite material. Boron content is 1-30w
Although it can be set arbitrarily within the range of t%, as shown in FIG. 2, if the boron content is set to about 10 wt%, it can be understood that the oxidation of graphite can be almost completely prevented at a high temperature of 600 ° C. .

Further, in the above embodiment, the coating of boron oxide formed by combining boron with oxygen cannot be expected to have lubricity, but since the balls 3 are formed of ceramics, the pockets of the cage 4 5 The coating of boron oxide on the inner surface is worn away to expose the graphite, and the lubrication performance of the bearing is exhibited.

Next, the results of a friction test simulating the use of a rolling bearing in a cage will be described. FIG. 4 shows this friction tester. Graphite A (containing no boron) and Graphite B (containing boron) using the cage material evaluation tester shown in FIG.
A comparative test was performed. For graphite B, tests were performed on three types of samples having boron contents of 1, 3, and 10 wt%, respectively. The cage material evaluation test machine of FIG.
The contact state of a rolling bearing (sliding contact between a cage and a rolling element and rolling sliding contact between a rolling element and a bearing ring) is simulated. The test was performed by bringing the retainer material test piece 10 into contact with the upper test piece 11 corresponding to the rolling element and performing a running-in operation for 10 minutes, and then bringing the upper test piece 11 into contact with the lower test piece 16 corresponding to the raceway. We are implementing. The retainer material test piece 10 is attached to a vertical shaft 12 and pressed against the upper test piece 11 by a weight 13 for cage load. Further, the lower test piece 16 is connected to the upper test piece 11 by a load lever 14 having a lower test piece weight 15.
Pressed to. As a result, the upper test piece 11 is rotated by the lower test piece 16 rotated by a device (not shown), and friction occurs between the upper test piece 11 and the holder material test piece 10. Next, the details of the test conditions are shown in Table 1.

[0010]

[Table 1]

Next, Table 2 shows the results of a friction test simulating the use of a rolling bearing in a cage.

[0012]

[Table 2] A: Coefficient of friction μ = 0.2 or less Very good. …: Coefficient of friction μ = 0.2 to 0.3 Good. Δ: Coefficient of friction μ = 0.3 or more. X: The cage material was damaged and the test was not possible.

As can be seen from Table 2, the boron content is 10 wt.
% Of graphite B10 containing 300 to 60%
Although the coefficient of friction is slightly higher in the temperature range of 0 ° C,
It can be seen that a very good friction coefficient is shown. Also,
For graphite A containing no boron, 100 to 50
Although a good friction coefficient is obtained in the temperature range of 0 ° C.,
Tests at elevated temperatures, above 00 ° C., can cause cage material failure. This breakage of the cage material is due to a reduction in the strength of the graphite itself due to oxidation. Therefore, when graphite containing no boron is used as a rolling bearing retainer at a temperature exceeding 500 ° C., it is considered that a problem such as breakage due to a decrease in strength occurs in a short time. Furthermore, in the case of graphites B1 and B3 having a low boron content, a good friction coefficient is obtained in a temperature range of 100 to 600 ° C, but at 700 ° C, the cage material may be damaged. For these B1 and B3 materials, 500
It is considered that it can be practically used as a retainer material only for a relatively short time use in a temperature range of -600 ° C.

Finally, the results of actually manufacturing a bearing for a rolling bearing using the graphite material of the present invention in which boron is dispersed and contained, and performing a performance test of the bearing are shown.
The test was performed by combining a total ceramic bearing equivalent to the angular contact ball bearing 7204 and a machined cage made of the graphite material of the present invention. FIG. 5 shows a schematic diagram of the tester, and Table 3 shows details of the test conditions.

[0015]

[Table 3]

The tester shown in FIG. 5 operates the test bearing by applying an axial load in a high-temperature atmosphere to evaluate the performance of the bearing. In the test, after heating to a predetermined temperature (700 ° C. in this test) in an electric furnace 17, a weight 1
9 and the load lever 20 apply an axial load. The test bearing 18 is rotated by the rotation of the motor 21 via the speed increaser 22 and the torque meter 23. The test was performed at a rotation speed of 1000 r / min at intervals of 10 minutes, and at a speed of 2000 r / min.
The method is performed in such a manner that the speed is increased by min jump. The test results are shown in FIG. 6. In the test using the B1 retainer, 3000 r /
In the test using the B3 retainer, the vibration value increased at 5000 r / min, and the test was terminated. After the test, when the bearing was checked, the cage was broken. In the test using the B10 retainer, the vibration value increased at 13000 r / min, and the test was terminated. After the test, the bearing was confirmed.
Although the rotational condition of one of the bearings was slightly deteriorated, no damage to the cage was observed. From the above results, usage conditions,
It was confirmed that the rolling bearing can be operated at high temperature and high speed by dispersing and containing an appropriate amount of boron in consideration of the use temperature.

Thus, the present invention can be well understood. Note that the inner ring 1 and the outer ring 2 may be formed of any material such as steel, stainless steel (for example, SUS440C), or a metal, such as SUS440C. More optimal. Further, the rolling bearing type is not limited to the ball bearing, and the present invention is also applied to a rolling bearing such as a cylindrical roller bearing.

[0018]

According to the present invention, since the boron of the cage of the rolling bearing contains boron dispersed therein, when used in a high temperature state, the surface of the cage becomes boron oxide by oxidation of boron. Coated. As a result, oxidation of the graphite is prevented, and a decrease in the strength of the graphite cage is prevented. Furthermore, since ceramics are used for the rolling elements, the coating of the boron compound on the inner surface of the cage pocket is worn away to expose the graphite, thereby exhibiting good lubricity.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rolling bearing of the present invention.

FIG. 2 is a state diagram when the rolling bearing of the present invention is used in a high temperature state.

FIG. 3 is a graph showing the results of an oxidation test of the present invention.

FIG. 4 is a cage material evaluation tester used for evaluation of the present invention.

FIG. 5 is a high-temperature bearing performance tester used for evaluation of the present invention.

FIG. 6 is a graph showing a result of a high-temperature bearing performance test at 700 ° C. of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Ball 4 Cage 5 Pocket 6 Boron oxide coating

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takeo Yoshioka 1-2-2 Namiki, Tsukuba, Ibaraki Pref. Inside the Technical Research Institute of Industrial Technology (72) Inventor Kazuhisa Kitamura 3-5-8 Minamisenba, Chuo-ku, Osaka-shi Mitsuhiro Within Seiko Co., Ltd. (72) Inventor Minoru Takeda 3-5-8 Minamisenba, Chuo-ku, Osaka-shi Koyo Seiko Co., Ltd. (72) Inventor Shigeyuki Ukita 5-7-12 Takeshima, Nishiyodogawa-ku, Osaka-Toyo Carbon Co., Ltd. 72) Inventor Toshiaki Sogabe 5-7-12 Takeshima, Nishiyodogawa-ku, Osaka Toyo Carbon Co., Ltd.

Claims (1)

[Claims] In a rolling bearing having an inner ring, an outer ring, a rolling element disposed between the inner and outer rings, and a graphite retainer for holding the rolling element, at least the rolling element is formed of ceramics and held. A rolling bearing characterized in that boron is dispersed and contained in graphite of a vessel.