JP2004084767A - Roller bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the reliability of electrolytic corrosion preventive effect at a low cost without changing the outside diameter of a bearing. <P>SOLUTION: In a roller bearing with a plurality of balls 3 interposed between an outer ring 1 and an inner ring 2, it is characterized in that an oxide film 7 is deposited on a ferrous material 6 containing 5 wt.% to 22 wt.% of chromium (Cr) in at least one component of the outer ring 1, the inner ring 2 and the balls 3. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention particularly relates to a rolling motor suitable for an air conditioner, a water heater, a ventilation fan, a fan motor using inverter control used for cooling, and a fan motor used for a device that performs inverter control.
[0002]
[Prior art]
Inverter control methods are becoming mainstream as control methods for home appliance motors.However, in the case of fan motors and the like, when an inverter is controlled or used in a device that performs inverter control, current is applied to rolling bearings during rotation. When flowing, sparks are generated at the rolling contact portions, causing electrolytic corrosion.
[0003]
As a rolling bearing having taken measures against electric corrosion, for example, as described in JP-A-7-12129, JP-A-8-100818, or JP-A-7-310748, silicon nitride is used as a rolling element. Incorporating a ceramic ball formed by pressure sintering mainly composed of, for example, coating an end surface of an inner ring or an outer ring with an insulating layer, or winding a resin material having excellent insulating properties such as PPS and PBT. .
[0004]
[Problems to be solved by the invention]
A rolling bearing incorporating a ceramic ball as a rolling element is excellent in insulation and is effective in preventing electrolytic corrosion, but has a problem that the price is high.
Further, in the case of a rolling bearing in which the end surface of the inner ring or the outer ring is coated with a ceramic, the coating may be peeled off when the bearing is inserted into a shaft or a housing.
[0005]
Furthermore, rolling bearings wound with a resin material are less expensive than rolling bearings incorporating ceramic balls, and can be expected to have insulation properties.However, since resin materials are generally wound on the outer diameter surface of the outer ring, the bearing outer diameter is φ This increases the size by several millimeters, so that not only the inner diameter of the housing needs to be changed, but also the resin portion becomes the outer diameter surface of the bearing and comes into contact with the housing or the like.
[0006]
The present invention has been made in order to solve such inconveniences, and an object of the present invention is to provide a rolling bearing that can increase the reliability of an electrolytic corrosion preventing effect at low cost without changing the outer diameter of the bearing. And
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a rolling bearing according to the present invention is a rolling bearing in which a plurality of rolling elements are interposed between an outer member and an inner member, wherein the outer member, the inner member, and the rolling member are provided. At least one component of the moving body is characterized in that an oxide film is formed on a steel material having a chromium (Cr) content of 5% by weight or more and 22% by weight or less.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory cross-sectional view for explaining a rolling bearing as an example of an embodiment of the present invention, and FIGS. 2 to 7 are explanatory cross-sectional views for explaining a rolling bearing as another embodiment of the present invention. It is sectional drawing.
[0009]
As shown in FIG. 1, this rolling bearing has a plurality of balls 3 interposed between an outer ring 1 and an inner ring 2 via a retainer 4, and has shield plates 5 at both ends in the axial direction. Is attached.
Here, in this embodiment, the content of chromium (Cr) as a material of the outer ring (outer member) 1, the inner ring (inner member) 2, and the ball (rolling element) 3 is 5% by weight or more and 22% by weight or less. An oxide film 7 is formed on the entire surface (including the race surfaces of the inner and outer rings) using a certain steel material 6.
[0010]
As a result, an insulating layer composed of the oxide film 7 is formed between the outer diameter of the outer ring 1 and the housing, between the inner diameter of the inner ring 2 and the shaft, and between the ball 3 and the race surface of the inner and outer rings. The current flowing toward the ball 3 and the inner ring 2 or the current flowing in the opposite direction can be reliably cut off, and the present invention can be suitably used for a fan motor by inverter control or a fan motor incorporated in a device for performing inverter control.
[0011]
Regarding the content of chromium (Cr), if the content is less than 5% by weight, the film thickness of the oxide film 7 is too thin to obtain sufficient insulating properties. 7 is thick and has excellent insulation properties, but when the chromium content is high, coarse eutectic carbides are easily formed, and when used for a rolling bearing, it causes peeling.
As a method of forming an oxide film on the surface of the steel material 6, there is a passivation treatment method in which a metal is immersed in a processing solution to form a corrosion product film on the surface of the metal densely and to a considerable thickness. In this embodiment, the oxide film 7 is formed on the surface of the steel material 6 by immersing the steel material 6 in a treatment solution containing chromic acid and sulfuric acid or nitric acid for a predetermined time.
[0012]
In this case, since the thickness of the fermented film is about 50 to 300 °, in order to make the oxide film thicker, the work-affected layer formed on the processed surface of the steel material 6 is removed, and then the passivation treatment is performed. Is preferably performed.
In this way, an oxide film of sub-μm to several μm can be formed on the surface of the steel material 6. In this embodiment, an oxide film 7 of 1 μm is formed on the surface of the Could be confirmed.
[0013]
When the oxide film 7 is formed, the surface becomes rough. Therefore, when the oxide film 7 is formed also on the inner and outer race surfaces as in this embodiment, the oxide film 7 is formed to prevent acoustic deterioration or the like due to surface roughness. After the formation of 7, the race surface of the inner and outer rings needs to be subjected to surface processing again to improve the surface roughness.
As is apparent from the above description, in this embodiment, since the insulating layer is formed by the oxide film 7, the film does not peel off when inserted into the shaft or the housing, and the reliability of the electrolytic corrosion preventing effect is improved. It is possible to increase the effect of preventing static electricity from flowing into the bearing.
[0014]
In addition, since the oxide film 7 is formed inside the steel material, it is possible to take measures to prevent electrolytic corrosion without changing the outer diameter of the bearing. Since the diameter is increased, it is not necessary to change the inner diameter of the housing or to previously process the outer diameter of the bearing by the thickness of the resin material.
Further, since the oxide film 7 can be easily formed by immersing the steel material 6 in a treatment solution containing chromic acid and sulfuric acid or nitric acid for a predetermined time, the oxide film 7 can be formed on a ceramic ball bearing or a bearing wound with a resin material. As a result, the manufacturing cost can be kept low.
[0015]
In the above-described embodiment, the case where the oxide film 7 is formed on the outer ring 1, the inner ring 2, and the ball 3 is taken as an example. However, this is not always necessary, and for example, as shown in FIG. The oxide film 7 is formed only on the inner ring 2 as shown in FIG. 3, the oxide film 7 is formed only on the outer ring 1 as shown in FIG. 3, or the oxide film 7 is formed only on the ball 3 as shown in FIG. It may be.
[0016]
Further, in the above embodiment, the case where the oxide film 7 is formed on all surfaces of the outer ring 1, the inner ring 2 and the ball 3 is taken as an example, but the passivation treatment is performed on the inner and outer race surfaces as described above. In such a case, the sound is reduced due to surface roughness. Therefore, as shown in FIG. 5, the oxide film 7 is formed on the surface of the outer ring 1 excluding the race surface and the surface of the inner ring 2 except the race surface. Is also good.
[0017]
Also in this case, depending on the application, an oxide film 7 is formed only on the surface of the outer ring 1 excluding the race surface as shown in FIG. 6, or as shown in FIG. The oxide film 7 can be formed only on the surface.
Furthermore, in the above-described embodiment, the case where the present invention is applied to a single-row bearing is adopted. However, the present invention is not limited to this, and the present invention may be applied to a double-row bearing. The present invention may be applied to a bearing, and the inner ring may be used as a shaft member.
[0018]
【The invention's effect】
As is clear from the above description, according to the present invention, the effect that the reliability of the electrolytic corrosion prevention effect can be improved at low cost without changing the bearing outer diameter dimension can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory sectional view for explaining a rolling bearing which is an example of an embodiment of the present invention.
FIG. 2 is an explanatory sectional view illustrating a rolling bearing according to another embodiment of the present invention.
FIG. 3 is an explanatory cross-sectional view illustrating a rolling bearing according to another embodiment of the present invention.
FIG. 4 is an explanatory cross-sectional view illustrating a rolling bearing according to another embodiment of the present invention.
FIG. 5 is an explanatory cross-sectional view for explaining a rolling bearing according to another embodiment of the present invention.
FIG. 6 is an explanatory sectional view for explaining a rolling bearing according to another embodiment of the present invention.
FIG. 7 is an explanatory cross-sectional view illustrating a rolling bearing according to another embodiment of the present invention.
[Explanation of symbols]
1: Outer ring (outer member)
2. Inner ring (inner member)
3. Ball (rolling element)
6 ... Steel material 7 ... Oxide film

Claims (1)

A rolling bearing having a plurality of rolling elements interposed between an outer member and an inner member, wherein at least one of the outer member, the inner member, and the rolling elements contains chromium (Cr). A rolling bearing characterized in that an oxide film is formed on a steel material having a ratio of 5% by weight or more and 22% by weight or less.

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