JP2004084792A - Rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrict a rise of temperature in a rolling bearing wherein heat radiation is hindered by a creep preventing part or an electrical insulating film. <P>SOLUTION: In this rolling bearing which has raceway rings 2 and 3, a rolling body 4 and a non-metal contact range 7 to be brought in contact with other members to be fitted to the raceway rings 1 and 2 without generating a metal contact, surface treatment for raising a radiation ratio to 0.9 or more is performed to a range wherein the rolling bearing is not brought in contact with other members. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rolling bearing.
[0002]
[Problems to be solved by the invention]
When a rolling bearing is used under high-speed rotation, high load conditions, etc., heat generation inside the rolling bearing becomes a problem. If the heat generation and the heat radiation are balanced, the temperature rise does not occur, but if the heat radiation amount is smaller than the heat generation amount, the temperature of the rolling bearing continues to rise.
[0003]
For example, when another metal member (shaft, housing, etc.) is attached to the raceway (inner ring / outer ring) of the rolling bearing, if heat is conducted to the other member to balance heat generation and heat dissipation, The temperature of the rolling bearing does not rise so much.
On the other hand, when the other member attached to the bearing ring is not made of metal, heat dissipation from the rolling bearing is generally not promoted due to low thermal conductivity and the temperature rises. If the race of the rolling bearing is provided with an elastic ring for preventing creep or an electric insulating coating, the rolling bearing will have an elastic ring for preventing creep or an electric insulating coating even if other members are made of metal. Therefore, heat is hardly transmitted from the rolling bearing to the other member through a member having low thermal conductivity, and the temperature rises because heat dissipation is not promoted.
[0004]
As described above, when the metal contact between the rolling bearing and the other member is broken, the temperature of the rolling bearing easily rises, and eventually seizure occurs. In the case of a rolling bearing in which grease is sealed, the grease deteriorates quickly and the life of the bearing is shortened. The present invention has been made in view of such a problem, and an object of the present invention is to suppress a temperature rise even in a rolling bearing in which heat dissipation is hindered.
[0005]
[Means for Solving the Problems]
The present invention relates to a rolling bearing having a raceway and a rolling element, and having a non-metallic contact area that comes into contact with other members attached to the raceway without making metallic contact. A rolling bearing characterized by having been subjected to a surface treatment for enhancing rolling resistance.
According to the present invention, as in the case where the other member is not metal, or the case where a member (rubber or resin or the like) having significantly lower thermal conductivity than the metal such as the anti-creep portion or the electric insulating film is provided on the raceway. Even if the rolling bearing has a non-metallic contact area, since the surface treatment for increasing the emissivity is performed, the heat radiation action from the area where the surface treatment is performed is improved, and the rolling without the surface treatment is performed. The temperature rise can be suppressed as compared with the bearing.
[0006]
The emissivity in the range where the surface treatment is performed is preferably 0.9 or more, and in this case, the temperature rise can be suppressed efficiently.
[0007]
Further, it is preferable that the surface treatment is a coating of a material having a heat resistance while increasing the emissivity of the rolling bearing. In this case, it becomes suitable for use at high temperatures. As the heat-resistant coating, a ceramic coating is preferable.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a rolling bearing 1 according to a first embodiment. The rolling bearing 1 is configured by arranging a rolling element 4 between an inner ring 2 and an outer ring 3, which are race rings. The rolling elements 4 are balls, and a plurality of balls 4 are held by a holder 5. The rolling bearing 1 has a shield 6 attached to one of the races (the outer ring 3 in the illustrated case), and is configured as a shield bearing. The shields 6 are provided on both end faces in the axial direction.
[0009]
An O-ring (elastic ring) 7 is mounted on the raceway (the outer periphery of the outer race 3 in the drawing) as a creep preventing portion for preventing creep. The O-rings 7 are made of rubber, for example, and are arranged side by side in pairs in the axial direction. A mounting groove 8 for mounting an O-ring 7 is formed in the outer peripheral surface 3a of the outer ring 3 in a circumferential direction. The rolling bearing 1 is filled with grease.
The races 2 and 3 are made of metal such as bearing steel, and the rolling elements 4 are formed of a ceramic material. The shield 6 is made of metal such as an iron plate.
[0010]
For example, when the rolling bearing 1 is used for inner ring rotation, a housing is attached to the outer peripheral surface 3 a side of the outer ring 3, and a rotating shaft is attached to the inner peripheral surface 2 a side of the inner ring 2.
Even if the rolling bearing 1 is mounted on another member such as a housing, the outer ring 3 is mounted on another member (housing) via the O-ring 7 which is a creep preventing portion, and thus the O-ring 7 contacts the other member. Thus, the other member is not in contact with the outer ring outer peripheral surface 3a.
Therefore, not only when the other member attached to the outer ring 3 is not made of metal, but also when the other member is made of metal, the state in which the conduction (radiation) of heat from the rolling bearing 1 to the other member (housing) is hindered. Has become. That is, if the other member is made of a metal having high thermal conductivity and is in contact with the outer ring 3, the heat generated in the rolling bearing 1 is conducted to the other member to promote heat dissipation. Since the rubber O-ring 7 having low heat conductivity is interposed between the outer ring 3 and the outer ring 3, the heat dissipation is suppressed.
[0011]
As described above, in the rolling bearing 1 of the present embodiment, the contact area of the outer ring 3 with the other member is the portion of the O-ring 7 which is a creep preventing portion, and the O-ring 7 is made of rubber and non-metallic. Therefore, it is a non-metal contact area. If the other member is non-metallic, the rolling bearing 1 has a non-metallic contact area even without the O-ring 7, and in this case, the entire outer peripheral surface of the rolling bearing 1 is a non-metallic contacting area. .
The outer ring 3 and the shields 6 and 6 are subjected to a surface treatment 9 in order to promote heat radiation obstructed by the non-metal contact area by the O-ring 7. This surface treatment 9 is a treatment for increasing the emissivity of the outer ring 3 and the surfaces of the shields 6 and 6. Here, the surface treatment 9 is performed by coating a material having a higher emissivity than the races 2 and 3 and the shield 6.
[0012]
Here, the metal that is the material of the races 2, 3 and the shield 6 of the rolling bearing 1 generally has a low emissivity, but the coating 9 is applied with a higher emissivity than the race 2 or the shield 6 so that the coating is performed. The heat radiation from the rolling bearing 1 can be promoted as compared with the case without the bearing 9.
[0013]
The coating 9 serving as a radiation range is formed in a range where the coating 9 is not in contact with other members and is an exposed outer surface of the rolling bearing 1 in order to perform heat radiation. The range not in contact with other members includes, for example, the range of the axial end face of the rolling bearing 1. In the present embodiment, the coating 9 is applied to the outer ring 3 and the shield 6. The coating 9 of the outer race 3 is applied to the outer peripheral surface 3a, the inner peripheral surface (excluding the raceway surface) 3b, and both axial end surfaces 3c, 3c of the outer race 3. The coating 9 can be similarly applied to the inner ring 2 except for the raceway surface. Although the coating 9 of the shield 6 is applied to almost the entire surface of the shield 6 in the illustrated example, it is sufficient to apply the coating 9 to at least the outer surface 6 a of the shield 6. By applying the coating 9 to almost the entire shield surface, the coating surface area can be increased and the heat radiation efficiency can be increased. The coating area can also be increased by applying the coating 9 to both the outer ring 3 and the shield 6. That is, the coating 9 can be applied to part or all of the range that does not come into contact with other members, and the coating range may be appropriately set in consideration of the bearing shape, use conditions, cost, and the like.
[0014]
In the present embodiment, the shields 6 are provided on both sides in the axial direction of the rolling bearing 1, but the shields 6 may be provided only on one side in the axial direction. Further, when the shields 6 are provided on both sides in the axial direction of the rolling bearing 1, the coating 9 may be applied to both the shields 6, 6 as shown in the drawing, or the coating 9 may be applied to only one of the shields 6. May be.
[0015]
As the material of the coating 9, a material having a high emissivity can be appropriately used. For example, the coating 9 can be provided by a ceramic coating or a coating of a high emissivity metal oxide. Preferably, an inorganic or organic coating in which particles made of a substance having a high emissivity such as silica or alumina are dispersed.
Further, the coating 9 may be performed by forming a carbon-based hard film such as DLC. Alternatively, it may be coated with a resin material such as an epoxy resin. Further, the emissivity can also be increased by applying black paint (preferably, matte black paint).
The coating material can be appropriately used as long as it has a high emissivity. However, when a material having heat resistance such as a ceramic material, a metal oxide, or DLC is used, it can withstand use in a high-temperature environment, which is preferable. . Further, when a ceramic material is used as the coating, particularly excellent heat dissipation can be obtained by radiation from the ceramic material.
[0016]
According to the rolling bearing 1 according to the present embodiment, heat radiation is higher than that of the rolling bearing 1 without the coating 9 due to the radiation range formed by the coating 9. Therefore, even if the rolling bearing 1 is used under conditions that generate heat, such as high-speed rotation and high load, when the heat radiation to other members such as the housing is hindered by the O-ring 7, the heat radiation from the coating 9 causes the rolling. The temperature rise of the bearing 1 can be suppressed. Therefore, seizure of the rolling bearing 1 can be prevented, and deterioration of grease can be prevented, so that the life of the rolling bearing 1 can be extended.
Moreover, in the rolling bearing 1 according to the present embodiment, since a lightweight ceramic material is used for the rolling element, the amount of heat generated from the rolling bearing 1 is suppressed by the effect of reducing the centrifugal force during high-speed rotation.
[0017]
FIG. 2 shows a rolling bearing 1 according to a second embodiment. In the rolling bearing 1, unlike the rolling bearing 1 according to the first embodiment, the outer ring 3 is not provided with the O-ring 7, and the electrical insulating coating 10 made of a synthetic resin is formed. Therefore, the electric insulating film 10 is in contact with other members (housing and the like) mounted on the outer ring 3 side, and the outer ring 3 is not directly in contact with the other members.
Therefore, also in the rolling bearing 1 according to the second embodiment, not only when the other member attached to the outer ring 3 is not made of metal, but also when the other member is made of metal, the other member (housing) is transferred from the rolling bearing 1 to another member (housing). In this state, heat conduction (heat radiation) is hindered by the electric insulating film 10. That is, since the electric insulating film 10 made of a synthetic resin having low thermal conductivity is interposed between the other member and the outer ring 3, the heat dissipation is suppressed.
[0018]
As described above, in the rolling bearing 1 of the present embodiment, the area of contact with other members on the outer ring 3 side is the electric insulating film 10, and the electric insulating film 10 is made of a synthetic resin and is nonmetallic. The contact area.
In the second embodiment, the coating 9 for promoting heat radiation is applied only to the shield 6. However, it may be applied to the races 2 and 3 as needed. In the second embodiment, the heat dissipation is hindered by the electric insulating film 10, but the heat dissipation is promoted by the coating 9, and the temperature rise can be suppressed.
Note that, in the second embodiment, the points that are not described are the same as in the first embodiment. The same reference numerals are given in the drawings.
[0019]
【Example】
Liquid ceramics (trade name: Shellac α, manufactured by Shellac Co., Ltd.) was applied to the outer ring 3 and the shield 6 of the rolling bearing 1 shown in FIG. 1 by spraying, dipping, or the like to form a thin film and perform coating. The emissivity of the coating 9 of the rolling bearing 1 is about 0.92, efficient heat radiation is performed by the radiant heat of the ceramics, and the heat resistance is excellent.
The coated rolling bearing was taken as an example, and the rolling bearing 1 of FIG. 1 in which the coating 9 was not applied was taken as a comparative example, and a test was performed under the following conditions.
<Test conditions>
Rotation speed: 10000 rpm
Load: Radial load increased from 400 kgf to 200 kgf every 24 h Lubrication: Grease (trade name: Isoflex NBU15 10% filled space)
[0020]
As shown in FIG. 3, in the example, the outer ring temperature is lower by about 10 ° C. than in the comparative example, and the temperature rise is suppressed. Moreover, it can be seen that in the example, the operation can be performed up to a higher load. Therefore, if the load is the same, the embodiment has less grease temperature degradation and a longer grease life, resulting in a longer life as a rolling bearing.
[0021]
【The invention's effect】
According to the present invention, since the heat radiation is promoted by the surface treatment for increasing the emissivity, the temperature rise of the rolling bearing can be suppressed even if the heat radiation due to the metal contact with other members is suppressed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a rolling bearing 1 according to a first embodiment.
FIG. 2 is a sectional view of a rolling bearing 2 according to a second embodiment.
FIG. 3 is a graph showing test results.
[Explanation of symbols]
1 rolling bearing 2 inner ring (track ring)
3 Outer ring (track ring)
4 balls (rolling element)
7 O-ring (creep prevention part; non-metal contact area)
9 Coating (surface treatment)
10 Electrical insulation film (non-metal contact area)

Claims (5)

In a rolling bearing having a raceway and a rolling element, and having a non-metallic contact range that comes into contact with other members attached to the raceway without making metal contact,
A rolling bearing characterized in that a surface treatment for increasing the emissivity is applied to a range not in contact with another member. 2. The rolling bearing according to claim 1, wherein an emissivity of the surface-treated area is 0.9 or more. The rolling bearing according to claim 1, wherein the non-metallic contact area is a creep preventing portion or an electric insulating film provided on the race. The rolling bearing according to any one of claims 1 to 3, wherein the surface treatment is a coating of a material having heat resistance while increasing the emissivity of the rolling bearing. The rolling bearing according to claim 1, wherein the surface treatment is a ceramic coating.

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