JP2004092720A - Electrically conducted rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrically conducted rolling bearing which can stably and satisfactorily maintain an electrically conducted state for a long time and is excellent in durability. <P>SOLUTION: The electrically conducted rolling bearing rotatably holds a plurality of rolling elements 3 between an inner race 1 and an outer race 2 via a retainer 4. In addition, a coating film 6 containing metals and solid lubricants is formed on at least one part of sliding parts and rolling parts. Otherwise, the electrically conducted rolling bearing holds the rolling elements 3 via the retainer 4 and a spacer composed of sintered elements containing metals and solid lubricants. <P>COPYRIGHT: (C)2004,JPO

Description

【００２７】
表１に示すように、金属と固体潤滑剤とを含有する被膜を設けることにより、充分な導電性が付与され、しかも耐久性も改善されることがわかる。
【００２８】
［被膜中の金属含有量の検証］
実施例１に従い、内輪外周面及び外輪内周面に、鉄含有量の異なる被膜を形成し、同様の導電性評価及び軸受耐久寿命評価を行った。結果を図２に示す。尚、図２において、○印のプロットが導電性評価値であり、△印のプロットが軸受耐久寿命評価値である。
【００２９】
図２から、被膜中の金属含有量が１０〜７０重量％のときに、導電性と軸受耐久寿命とが共に優れることがわかる。
【００３０】
［被膜の膜厚の検証］
実施例１に従い、内輪外周面及び外輪内周面に、鉄含有量５０重量％で、膜厚の異なる被膜を形成し、同様の導電性評価及び軸受耐久寿命評価を行った。結果を図３に示す。尚、図３において、○印のプロットが導電性評価値であり、△印のプロットが軸受耐久寿命評価値である。
【００３１】
図３から、被膜の膜厚が０．２μｍ〜１０μｍのときに、導電性と軸受耐久寿命とが共に優れることがわかる。
【００３２】
【発明の効果】
以上説明したように、本発明によれば、高温時においても、導電状態を長期にわたって安定して良好に維持することができ、耐久性に優れた通電転がり軸受が提供される。
【図面の簡単な説明】
【図１】本発明の通電転がり軸受の一実施形態を示す断面図である。
【図２】実施例で得られた、被膜中の鉄含有量と、導電性及び耐久性との関係を示すグラフである。
【図３】実施例で得られた、被膜の膜厚と、導電性及び耐久性との関係を示すグラフである。
【符号の説明】
１　内輪
２　外輪
３　玉（転動体）
４　保持器
５　シール部材
６　被膜[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a rolling bearing, and more particularly, to a so-called energized rolling bearing used for a photosensitive drum such as an office copying machine or a laser beam printer, or a peripheral device thereof.
[0002]
[Prior art]
Many rolling bearings are used in general office equipment and information equipment such as copying machines and laser beam printers. In these general bearings, grease is sealed therein, and an oil film of grease is formed on the raceway surfaces of the inner and outer rings and the rolling elements, so that the metals are not in contact with each other. Therefore, these rolling bearings have a problem that static electricity is easily generated by rotation, and the generated static electricity induces image noise.
[0003]
Therefore, in rolling bearings used in such applications, the inner and outer rings and the rolling elements are brought into a conductive state by enclosing conductive grease containing carbon black, thereby suppressing generation of static electricity (for example, JP-A-47-21402, JP-A-57-3897). In the present specification, the rolling bearing provided with such conductivity is referred to as an “energized rolling bearing”.
[0004]
However, in a current-carrying rolling bearing filled with conductive grease, the electrical resistance between the inner and outer rings shows a low value due to the conductive grease at the beginning of rotation, but the conductivity gradually decreases with time. Go. This is because the conductive grease initially exists sufficiently between the raceway surfaces of the inner and outer rings and the contact surface between the rolling elements, but is gradually removed from the contact surfaces with the passage of time, and again between the contact surfaces. This is thought to be due to the difficulty of entry. The reason why it is difficult to re-enter the space between the contact surfaces is that the conductive grease contains a large amount of carbon black to provide higher conductivity, and has a very low consistency.
[0005]
In order to solve such a problem, for example, in a current-carrying rolling bearing described in Japanese Patent No. 2579798, the consistency of conductive grease is increased to the same level (250 to 350) as that of general grease, and the inner and outer rings and holding It has been proposed that at least one of the container and the seal member is provided with grease guide means for guiding the conductive grease to the raceway surfaces of the inner and outer races so that the conductive grease can easily enter between the contact surfaces.
[0006]
[Problems to be solved by the invention]
However, even if the grease guiding means is provided, the solution will not be a drastic solution, and in a current-carrying rolling bearing in which conductive grease is sealed, a decrease in conductivity with time is inevitable in any structure. In general, as the consistency increases, the amount of carbon black decreases and the conductivity also decreases. Therefore, there is naturally an upper limit to increasing the consistency.
[0007]
Rolling bearings used at high temperatures, such as heat rolls, are required to maintain conductivity at higher temperatures, but no effective solution has been found yet.
[0008]
Therefore, an object of the present invention is to provide a current-carrying rolling bearing that can stably and favorably maintain a conductive state even at a high temperature for a long period of time and has excellent durability.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a method for rollingly holding a plurality of rolling elements between an inner ring and an outer ring via a retainer, and at least one of a sliding position and a rolling position. And a current-carrying rolling bearing provided with a coating containing a metal and a solid lubricant.
[0010]
Further, the present invention is characterized in that a plurality of rolling elements are rotatably held between an inner ring and an outer ring via a cage made of a sintered body containing a metal and a solid lubricant. To provide an energized rolling bearing.
[0011]
Further, the present invention is characterized in that a plurality of rolling elements are rotatably held between an inner ring and an outer ring via a spacer formed of a sintered body containing a metal and a solid lubricant. Provide a current-carrying rolling bearing.
[0012]
According to the above-described current-carrying rolling bearing of the present invention, the good lubricity of the solid lubricant is maintained in any case while the good lubricity of the metal is maintained by the presence of the coating made of the conductive metal and the solid lubricant. , And functions as a current-carrying rolling bearing stably over a long period of time. Similar effects can be obtained by forming the cage or the spacer as a sintered body containing a metal and a solid lubricant.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a current-carrying rolling bearing of the present invention will be described in detail with reference to the drawings.
[0014]
In the present invention, the configuration of the bearing itself is not limited, and for example, a ball bearing as shown in FIG. 1 can be exemplified. This ball bearing is provided with an inner ring 1, an outer ring 2, a ball 3 as a rolling element, and a retainer 4 for holding the ball 3 so as to be able to roll, and also to prevent foreign matter from entering from outside. The seal member 5 is fixed to the outer race 2. However, in the present invention, a coating 6 containing a metal and a solid lubricant is provided on at least one of a sliding point and a rolling point, for example, as shown in the figure, on the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2. Is formed.
[0015]
Various metals can be appropriately used as the metal as the material for forming the coating 6, and among them, iron, nickel, cobalt, chromium, tungsten, tin, copper, and the like can be suitably used. These metals may be used alone or in combination of two or more as necessary.
[0016]
Various solid lubricants conventionally used for bearings and the like can be appropriately used as a solid lubricant as a material for forming the coating 6, and among them, molybdenum disulfide, tungsten disulfide, polytetrafluoroethylene, etc. , Graphite and the like can be suitably used. These solid lubricants may be used alone or in combination of two or more, if necessary. It should be noted that gold and silver also act as solid lubricants, and are used here as solid lubricants, not as metals.
[0017]
The content of the metal in the coating 6 is preferably in the range of 10 to 70% by weight. If the proportion of the metal is less than 10% by weight, the effect of imparting conductivity is small, and if it exceeds 70% by weight, although high conductivity is obtained, the lubricating performance is reduced due to too little solid lubricant, and the durability is reduced. It is not preferable in respect of the point.
[0018]
The coating 6 may contain an inorganic binder such as a polyimide or polyamideimide-based synthetic resin-based binder, or water glass as long as the effects of the present invention are not impaired, in order to improve the film-forming properties. it can.
[0019]
The method of forming the coating 6 is not particularly limited, but includes a method of applying a coating material containing a metal and a solid lubricant to a coating forming portion by spraying, a method of forming a coating using a ball mill, and the like. It can be suitably mentioned.
[0020]
The thickness of the coating 6 can be appropriately set as required, but is preferably 0.2 μm to 10 μm. If the film thickness is less than 0.2 μm, the durability of the bearing may decrease. If the film thickness exceeds 10 μm, the excess coating wears, and the abrasion powder hinders the rotation of the bearing, thereby shortening the bearing life. May be shorter.
[0021]
Further, in the energized rolling bearing of the present invention, the cage 4 may be formed of a sintered body made of the above-described film forming material. Alternatively, although not shown, a spacer may be formed from the same sintered body and used instead of the retainer 4.
[0022]
【Example】
Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
[0023]
(Examples 1 to 4, Comparative Example 1)
As a test bearing, a deep groove ball bearing (nominal number 608; inner diameter 8 mm, outer diameter 22 mm, width 7 mm) was used. In Examples 1 to 4, coatings having the composition and thickness shown in Table 1 were applied to the inner ring outer peripheral surface and the outer ring inner surface. It was formed on the peripheral surface (see FIG. 1). The film was formed by spray coating a film-forming material having the composition shown in Table 1. In Comparative Example 1, a coating was not formed, and 0.25 g of commercially available conductive grease (KS660; manufactured by Shin-Etsu Chemical Co., Ltd.) was sealed in the bearing. Then, for these test bearings, the following conductivity evaluation and bearing durability life evaluation were performed. The results are also shown in Table 1.
[0024]
[Conductivity evaluation]
The electrical resistance between the inner ring and the outer ring during rotation of the bearing was measured under the following conditions.
・ Rotation speed: 100 rpm
・ Radial load: 29.4N
・ Temperature: 25 ° C
The evaluation value of the conductivity was shown as a ratio with the electric resistance value of the test bearing of Comparative Example 1 three hours after the start of rotation.
[0025]
[Bearing durability life evaluation]
The bearing life was measured under the following conditions.
・ Rotation speed: 1000 rpm
・ Radial load: 196N
・ Temperature: 230 ° C
The evaluation value of the bearing durability life was shown by a ratio with the bearing durability life of the test bearing of Comparative Example 1 three hours after the start of rotation.
[0026]
[Table 1]

[0027]
As shown in Table 1, it can be seen that by providing a coating containing a metal and a solid lubricant, sufficient conductivity is imparted and durability is improved.
[0028]
[Verification of metal content in coating]
According to Example 1, coatings having different iron contents were formed on the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, and the same conductivity evaluation and the same evaluation of the durability of the bearing were performed. FIG. 2 shows the results. In FIG. 2, the plots marked with ○ are the conductivity evaluation values, and the plots marked with △ are the bearing durability life evaluation values.
[0029]
FIG. 2 shows that when the metal content in the coating is 10 to 70% by weight, both the conductivity and the durability life of the bearing are excellent.
[0030]
[Verification of film thickness]
According to Example 1, coatings having different iron thicknesses with an iron content of 50% by weight were formed on the outer peripheral surface of the inner ring and the inner peripheral surface of the outer ring, and the same conductivity evaluation and bearing durability life evaluation were performed. The results are shown in FIG. In FIG. 3, the plots marked with ○ are the conductivity evaluation values, and the plots marked with Δ are the bearing durability life evaluation values.
[0031]
FIG. 3 shows that when the film thickness is from 0.2 μm to 10 μm, both the conductivity and the bearing durability life are excellent.
[0032]
【The invention's effect】
As described above, according to the present invention, a current-carrying rolling bearing that can stably and favorably maintain a conductive state for a long time even at a high temperature and has excellent durability is provided.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of a current-carrying rolling bearing of the present invention.
FIG. 2 is a graph showing the relationship between the iron content in a coating film and the conductivity and durability obtained in Examples.
FIG. 3 is a graph showing the relationship between the film thickness, conductivity, and durability obtained in Examples.
[Explanation of symbols]
1 inner ring 2 outer ring 3 balls (rolling element)
4 Cage 5 Sealing member 6 Coating

Claims (5)

A coating film that holds a plurality of rolling elements rotatably via a retainer between an inner ring and an outer ring, and includes a metal and a solid lubricant in at least one of a sliding position and a rolling position. A current-carrying rolling bearing, characterized by forming: The current-carrying rolling bearing according to claim 1, wherein the coating contains 10 to 70% by weight of a metal. The current-carrying rolling bearing according to claim 1, wherein a thickness of the coating is from 0.2 μm to 10 μm. A current-carrying rolling bearing characterized in that a plurality of rolling elements are rotatably held between an inner ring and an outer ring via a cage made of a sintered body containing a metal and a solid lubricant. A current-carrying rolling bearing characterized in that a plurality of rolling elements are rotatably held between an inner ring and an outer ring via a spacer made of a sintered body containing a metal and a solid lubricant.

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