JPH09229072A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of a rolling bearing under the environment such as in vacuum, high temperature, corrosive gas, liquid, or molten metal in which ordinary lubricant such as oil or grease can not be used by improving shift adhesiveness of solid lubricant from a self-lubricating retainer. SOLUTION: This rolling bearing is constituted of an outer ring 2, an inner ring 3, and rolling bodies 4 respectively made of silicon nitride ceramics, and a retainer 5 made of polytetrafluoroethylene, and the surface roughness of the respective raceway surfaces of the outer ring 2 and the inner ring 3 are set in the range of 0.1μmRa-3.2μmRa.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a rolling bearing used in an environment where normal lubricants such as oil and grease cannot be used in vacuum, high temperature, corrosive gas, liquid or molten metal. It is a thing.

[0002]

2. Description of the Related Art Conventionally, as a rolling bearing of this type used in an environment where ordinary lubricants such as oil and grease cannot be used, a self-lubricating cage mainly composed of polytetrafluoroethylene and a ceramic rolling element are used. Rolling bearings including are known (Japanese Patent Application Laid-Open No. 3-255224, Japanese Utility Model Publication No.
82431, Kaikaihei 6-76720).

[0003]

However, in this type of rolling bearing, the rolling life must be dependent on the lubrication by the transfer of the solid lubricant from the cage. The important technical issue is whether or not to transfer. However, in each of the above-mentioned conventional techniques, there is still room for improvement in this respect.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to improve the transferability of the solid lubricant from the self-lubricating cage. The purpose is to extend the rolling life in an environment where normal lubricants such as oil and grease cannot be used, such as in vacuum, high temperature, in corrosive gas, in liquid, or in molten metal.

[0005]

In order to achieve the above object, the technical means of the present invention is such that at least the rolling elements are made of ceramics, and the surface roughness of the raceways of the outer ring and the inner ring is 0.1 μmRa or more. .2 μmRa or less,
The cage is made of self-lubricating material.
In addition, in this specification, "Ra" represents arithmetic mean roughness.

[0006]

[Operation] By the above technical means, the race ring (outer ring and inner ring)
The surface roughness of the raceway surface is 0.1 μmRa or more and 3.2 μmRa.
Since it is in the following range, its surface roughness is 0.1 μmRa.
Compared with conventional rolling bearings of less than, vibration during rotation becomes large.

As a result, the chances of the self-lubricating cage coming into stronger contact with the rolling elements are increased, so that the transfer of the solid lubricant from the self-lubricating cage to the rolling elements can be increased.

Since the ceramic rolling element is used, the rolling element wears the raceway surface smoothly while maintaining the surface roughness due to its excellent wear resistance at the initial stage of rotation. Then, after the raceway surface of the bearing ring becomes smooth (surface roughness is less than 0.1 μmRa), the vibration becomes low, and good lubrication is achieved by the solid lubricant that is transferred to the rolling elements in an appropriate amount and uniformly.

Thus, the ceramic rolling elements are hard to wear and maintain a smooth surface, so that the solid lubricant is transferred from the self-lubricating cage in an appropriate amount and uniformly.
Good lubrication is achieved.

Therefore, the increase of the transfer effect due to the initial vibration is controlled by the surface roughness of the bearing ring raceway surface, and the smooth wear before the solid lubricant on the bearing ring raceway surface is transferred is made by using the ceramic rolling element. This is achieved by the fact that lubrication after smooth wear of the bearing ring raceway is performed by transfer of solid lubricant from the ceramic rolling elements. Can be extended.

[0011]

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 in the drawings shows one embodiment of the rolling bearing of the present invention. The rolling bearing 1 is a ball bearing composed of an outer ring 2, an inner ring 3, a rolling element 4 and a cage 5. Although the present invention will be described based on the above, the present invention can be applied to a roller bearing, both a radial bearing and a thrust bearing, and can be appropriately selected and applied within the scope of the present invention.

The outer ring 2 and the inner ring 3 are respectively provided with raceway surfaces 2
The surface roughness of a and 3a is 0.1 μmRa or more and 3.2 μm or more.
It is configured to be in the range of Ra or less. Further, since the following rolling elements 4 are made of ceramics, the outer ring 2,
The material of the inner ring 3 may be steel or ceramics. When the surface roughness is 0.1 μmRa or less, the vibration during rotation becomes too small, so the self-lubricating cage rarely comes into contact with the rolling elements, and the solid lubricant is transferred from the self-lubricating cage to the rolling elements. There are few clothes. The surface roughness is 3.
When it is 2 μmRa or more, the vibration becomes excessive, so that too many transfers occur or uneven transfer occurs, which rather hinders lubrication.

The rolling element 4 is made of a ceramic material having high wear resistance, and examples of the ceramic material include silicon carbide, alumina, zirconia, etc. in addition to silicon nitride.

The cage 5 is made of a material having a self-lubricating property and is made of, for example, polytetrafluoroethylene (PTF).
E), ethylene-tetrafluoroethylene copolymer (E
TFE), a fluororesin typified by tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), graphite, molybdenum disulfide, and the like.

In order to confirm the effect of the present invention, Example 1
8 and Comparative Examples 1 to 8 using several kinds of deep groove ball bearings, a rotation test was conducted with the test apparatus shown in FIG. The results of the rotation test are shown in Table 1, and the relationship between the surface roughness (μmRa) of the bearing ring raceway surface and the rolling life (h) is shown in FIG.
Shown in

[Examples 1 to 4 and Comparative Examples 1 to 3] A race ring (outer ring, outer ring, made of silicon nitride ceramics (Si ₃ N ₄ ) having a surface roughness of the raceway surface in the range of 0.05 μmRa to 9.4 μmRa.
Inner ring), silicon nitride ceramics (Si ₃ N ₄ ) rolling elements and polytetrafluoroethylene (PTFE) cage. "Examples 5-8, Comparative Examples 4-6" The surface roughness of the raceway surface was
Consists of race rings (outer ring, inner ring) made of stainless steel (SUS440C) in the range of 0.05 μmRa to 9.4 μmRa, rolling elements made of silicon nitride ceramics (Si ₃ N ₄ ) and cage made of polytetrafluoroethylene (PTFE) . “Comparative Example 7” Raceway rings (outer ring, inner ring) made of silicon nitride ceramics (Si ₃ N ₄ ) having a surface roughness of 1.0 μmRa, rolling elements made of silicon nitride ceramics (Si ₃ N ₄ ) and steel. Consists of a cage made of (SUS304 stainless steel). [Comparative Example 8] Raceway rings (outer ring, inner ring) made of stainless steel (SUS440C) having a surface roughness of the raceway of 1.0 μmRa, rolling elements made of stainless steel (SUS440C), and cages made of polytetrafluoroethylene (PTFE) Composed of.

[0017]

[Table 1]

From the results shown in Table 1 and FIG. 3, the following can be seen.

In comparison with the rolling life of Comparative Example 1 showing a bearing whose surface raceway surface used conventionally is less than 0.1 μmRa, the surface roughness of the bearing ring raceway surfaces shown in Examples 1 to 4 is compared with the rolling life of Comparative Example 1. In the case of bearings having a surface roughness of 0.1 μmRa to 3.2 μmRa, a significant extension of rolling life was confirmed in all cases (the → mark in Table 1 and FIG. 3 indicates the display time (h) or more, that is, In this test, it was stopped at 190 h, but it is shown that a rolling life (h) longer than that was actually obtained.)

Further, the surface roughness of the bearing ring raceway surface is 3.2μ.
When it exceeds mRa (Comparative Examples 2 and 3), Examples 1 to 4 are used.
The rolling life was shorter than that of the bearing.

Further, from the results of Examples 5 to 8 and Comparative Examples 4 to 6, similarly, the surface roughness range of the present invention (0.1 μmR
It was found that the bearings in the range of a to 3.2 μmRa) have a longer life than bearings outside the range.

Comparative Example 7 in which the races, rolling elements, and raceway raceway surfaces have the same surface roughness and the cage material is made of steel steel different from that of polytetrafluoroethylene of Example 2, is used. However, since it is not possible to effectively transfer the solid lubricant from the cage, it can be seen that the rolling life is extremely short as compared with Example 2.

Stainless steel (SUS440C) having the same race ring material, raceway raceway surface roughness and cage material, but different rolling element material from the silicon nitride ceramics (Si ₃ N ₄ ) of Example 6 was used. ), The rolling element surface is rough before the transfer from the self-lubricating cage is obtained because it is a rolling element made of stainless steel, and rolling is extremely extreme as compared with Example 6. You can see that the life is short.

[0024]

According to the present invention, at least the rolling elements are made of ceramics, the surface roughness of the raceway surface (outer ring and inner ring) is in the range of 0.1 μmRa to 3.2 μmRa and the self-lubricating cage. In order to improve the transferability of the solid lubricant from the self-lubricating cage,
The rolling life was extended in environments where normal lubricants such as oil and grease cannot be used, such as high temperatures, corrosive gases, liquids, and molten metals.

That is, after the surface roughness of the raceway surface increases the initial vibration, the transfer effect of the solid lubricant increases, and after the raceway surface of the ceramic ring has been smoothly worn, Since it can be performed by transferring more solid lubricant from the ceramic rolling element, it is possible to extend the rolling life in an environment where normal lubricants such as oil and grease cannot be used.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a rolling bearing according to the present invention, which is partially omitted.

FIG. 2 shows an outline of a testing machine for confirming the rotational performance of the rolling bearing of the present invention.

FIG. 3 shows the relationship between rolling surface life and rolling life of the raceway surface.

[Explanation of symbols]

 1: Rolling bearing 2: Outer ring 3: Inner ring 2a, 3a: Raceway surface 4: Rolling element 5: Cage

Claims (1)

[Claims] 1. A rolling bearing comprising an outer ring, an inner ring, rolling elements and a cage, wherein at least the rolling elements are made of ceramics, and the surface roughness of the raceways of the outer ring and the inner ring is 0.1 μmR.
A rolling bearing characterized in that it is in the range of a to 3.2 μmRa and less, and the cage is self-lubricating.