JP2002139052A - Rolling bearing for business machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing for business machine free of use of any rust preventive oil in which the anti-corrosiveness is enhanced and whereto electroconductiveness is given. SOLUTION: The rolling bearing 1 for business machine is structured so that balls/rollers 3 are installed between an inner ring 2 and outer ring 3 and supports a rotary part. The inside surface of the inner ring 2 and the outside surface of the outer ring 3 are coated with a film 7 having anti-corrosiveness and electroconductiveness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing for an office machine which supports a rotating section of the office machine, and more particularly to an optical section, a paper feeding section, a developing section, and a fixing section of an office machine such as a copying machine or a printer. The present invention relates to a rolling bearing suitable for supporting a rotating unit such as a paper unit.

[0002]

2. Description of the Related Art A bearing used in office equipment such as a copying machine has a corrosion resistance to a high-temperature and high-humidity use environment for fixing toner and stabilizes an image of a photosensitive drum and the like supported by the bearing. It is required to be conductive so as to be able to conduct electricity for charging and to conduct electricity for discharging electricity.

Heretofore, the corrosion resistance of the bearing has been ensured by applying a rust-preventive oil to the bearing surface. As the rust preventive oil, a synthetic hydrocarbon oil, a mineral oil, or the like is used. Each of these has an effect of preventing the occurrence of rust, and is a rust prevention technique generally performed in a conventional bearing using bearing steel. In addition, the copier, after charging the rotating photosensitive drum, removes electricity to the shaft member side except for the character and image portions, thereby adsorbing toner to the character and image portions, transferring the toner to paper, and performing development. I have. For this reason, the function required for the bearing in the apparatus is a conductive function for energization and static elimination for ensuring static elimination from the charged photosensitive drum to the shaft member and stabilizing an image.

In order to satisfy such required functions, a method of obtaining a current-carrying action by using a brush between a shaft member supporting a bearing and a drum has conventionally been adopted. It employs a method in which conductive grease is used to energize and remove electricity from the outer ring by energizing the bearing rolling parts. That is, in order to impart conductivity to the bearing, conductive grease has conventionally been indispensable.

On the other hand, use of a polymer material for the bearing support has been increasing in order to reduce the weight of an apparatus using the bearing and to reduce the cost of constituent members. That is, the bearing support portion (photosensitive drum, fixing roller, etc.) used in the device, particularly the housing portion to which the outer ring is fixed is also made of a polymer material,
The resin material used is high impact polystyrene (HIPS), which is a copolymer with polystyrene (PS) and ethylene for the purpose of improving toughness, or polyoxymethylene (POM) or polycarbonate ( PC) and the like.

[0006]

As described above, in order to obtain the corrosion resistance of the bearing, it is conventionally necessary to use a rust-preventive oil. It has been found that rust oil has the effect of deteriorating the material strength and leading to destruction by continuous stress (hereinafter referred to as chemical attack).

[0007] This is because the rust-preventive oil penetrates into the domains constituting the polymer, and the material strength is reduced. Further, in the bearing from which the rust preventive oil has been removed, there is a problem that corrosion resistance is reduced and rust is generated early. As a method that does not use rust preventive oil, corrosion resistance is improved by using stainless steel instead of bearing steel.However, there is a problem that processing efficiency is reduced, manufacturing costs are increased, and competitiveness in the market is lost. is there.

Conventionally, conductive grease is indispensable in order to ensure conductivity. However, the conductive grease does not have a sufficiently low resistance value of about 10 ³ Ω, and the shaft is connected to the rotating drum through a bearing. There is a possibility that static elimination toward the member may be insufficient. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a rust-proof oil-free office machine rolling bearing having improved corrosion resistance of the bearing and imparted conductivity.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a rolling bearing for office machines, wherein a rolling element is disposed between an inner ring and an outer ring to support a rotating portion. For at least one of the part and the outer diameter part of the outer ring,
It is characterized in that a coating having corrosion resistance and conductivity is formed, thereby making it possible to remove oily components from the bearing surface.

[0010] Naturally, the coating is required to have higher corrosion resistance than the base material of the bearing. That is, the performance required for the film to be formed has a surface specific resistance smaller than the resistance value of the conductive grease, and at least SUS
It is desirable to have corrosion resistance equivalent to 440C. Also,
It is desirable that the film has a low material and a low film formation cost.

Examples of the coating satisfying these conditions include a coating formed by electroless nickel plating, a coating formed by forming phosphate crystals on the surface of the bearing, and a coating formed by forming tin on the bearing surface.

Corrosion resistance such as a coating made of a metal noble than iron or a coating made by reacting the surface with phosphate on the inner ring inner diameter portion and the outer ring outer diameter portion in contact with the rotation supporting member (shaft member or housing). By forming a conductive coating having the above-mentioned structure, it is possible to improve the corrosion resistance of the bearing while ensuring the conduction of an electric resistance of a predetermined value or less between the shaft member and the housing. As a result, there is no need to apply rust preventive oil.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings. This embodiment is an example in the case of forming a film by the above “electroless nickel plating”. As shown in FIG. 1, the rolling bearing 1 according to the present embodiment includes a plurality of rolling elements 4 (balls) interposed between an inner ring 2 and an outer ring 3. And the outer diameter portion of the outer race 3 is fixed to the bearing support 7 of the rotating drum, so that the bearing support 7 of the rotating drum is fixed.
Is rotatably supported.

The surfaces of the inner ring 2 and the outer ring 3, in particular, the inner ring 2
The coating 7 is formed on the inner diameter portion of the outer ring 3 and the outer diameter portion of the outer ring 3 by electroless nickel plating. The coating 7 by “electroless nickel plating” is plated in a treatment tank while rotating the barrel by rotating several thousand to tens of thousands of inner and outer rings 2 and 3 of the bearing 1 in a stainless steel barrel (basket) container. It is performed by applying. Here, the content of phosphorus in the nickel plating is 2-1.
Annealing by heat is not performed at about 5%.
The corrosion resistance and hardness are improved by co-depositing phosphorus. However, since the electrical resistance increases as the amount increases, the content of phosphorus in the nickel plating is preferably about 2 to 15%.

Further, the thickness of the plating is 2 μm or more and 1 μm or more.
0 μm or less is desirable. If it is less than 2 μm, there is not enough corrosion resistance due to variations in film thickness, and if it exceeds 10 μm, the fitting allowance becomes large, and the fitting between the inner and outer rings 2 and 3 of the bearing 1 and the shaft member 6 or the bearing support portion 7 of the rotating drum is performed. The pressure may increase and the bearing clearance may be reduced and seizure may occur, or the bearing support 7 of the rotating drum may be deformed.

As described above, by plating the surface of the bearing 1 with a metal which is more noble than iron, the corrosion resistance can be improved as compared with the surface of the bearing steel even in a high-temperature and high-humidity environment. Then, a coating 7 having corrosion resistance and conductivity is formed on the inner diameter portion of the inner ring 2 and the outer diameter portion of the outer ring 3 which are in contact with the rotation supporting member (the shaft member 6 and the bearing support portion 7 of the rotating drum). By doing so, there is no need to apply rust preventive oil. Therefore, even if a polymer material is used for the shaft member 6 and the bearing support portion 7 (housing) of the rotating drum for the purpose of weight reduction or the like, it is possible to prevent a chemical attack on the shaft member 6 and the like.

The bearing 1 provided with the galvanized coating 7 is less expensive than the case where the bearing 1 is made of stainless steel. The coating 7 has a surface specific resistance of 1000.
Since the electric resistance is smaller than Ω, which is smaller than that of the conventional conductive grease, the energization / discharge of the shaft member 6 and the bearing support 7 of the rotating drum is improved.

Next, a second embodiment will be described. The same parts as those in the above embodiment are denoted by the same reference numerals and described. In the second embodiment, the coating 7 is formed by the above chemical conversion treatment. That is, the inner and outer rings 2 and 3 are immersed in a surface conditioning agent and a chemical conversion treatment solution to form a reaction layer (coating 7) of a phosphate compound having a thickness of 2 μm or more and 10 μm or less on the surface layer. This treatment also performs a chemical conversion treatment while rotating using a stainless steel barrel.

Although the electric resistance is lower than that of the metal surface, the electric resistance is smaller than the resistance of the grease, so that it can provide the functions of charging and discharging and has corrosion resistance. This has the same operation and effect as the first embodiment.
Here, when the film thickness is 2 μm or less, the corrosion resistance is insufficient,
On the other hand, when the film thickness is greater than 10 μm, the electric resistance tends to increase. For this reason, a film thickness of 2 μm or more and 10 μm or less is preferable.

Next, a third embodiment will be described. The same parts as those in the above embodiment are denoted by the same reference numerals and described. In the third embodiment, the coating 7 is formed by forming tin on the surface of the bearing 1. That is, tin is used as a polishing stone (media: for example, in a spherical shape) in a high-speed honing process, and is shot at a speed of 200 m or more per second on the surface to be processed. , 3 are coated.

Since tin is a metal nobler than iron, it is excellent in corrosion resistance and has a small surface resistance, so that the conductive performance can satisfy the required performance of the bearing for office machines. As a result, the same operation and effect as in the first embodiment are obtained.

[0022]

Example 1 "Example 1" Based on the first embodiment, electroless nickel plating was applied to the surfaces of the inner and outer rings 2 and 3 of the bearing 1, and a temperature cycle test of 20 ° C and 50 ° C at a relative humidity of 90% was performed. Was done. At this time, a 0.5% salt water was used as a humidity atmosphere.

The bearing 1 has an outer diameter of 19 mm, an inner diameter of 8 mm, and a width of 6
Using a small-diameter ball bearing of 200 mm, inner and outer rings 2 and 3 are loaded together in a stainless steel barrel container (2% of the processing capacity), electrolytic treatment, pickling, activation treatment, and 70 ° C. Electroless nickel plating was applied. As the nickel plating solution, Nicolon PAL manufactured by Okuno Pharmaceutical Co., Ltd. was used. FIG. 2 shows the relationship between the time until the occurrence of rust and the plating thickness.

As can be seen from FIG. 2, the effective film thickness range in which the effect on corrosion resistance can be obtained is 2 μm or more and 10 μm or less, and preferably 3 μm or more and 5 μm or less. here,
If the film thickness is less than 2 μm, it is assumed that the substrate (steel 1 steel) is exposed due to uneven plating, and the time until rust is generated becomes extremely short. On the other hand, if the thickness is more than 10 μm, the clearance inside the bearing increases, which is not desirable.

[Second Embodiment] The above-described bearing 1 was subjected to the following manganese phosphate treatment. Using PL-55 (trade name) manufactured by Nippon Parkerizing Co., Ltd. as a surface conditioner, the same PF-MIA or PF-M5
To form manganese phosphate crystals on the sliding surface. As a preferable treatment method, the concentration of the surface conditioner is 2 to 8 g / L, the pH is 9 or more, and the chemical conversion treatment solution dissolves manganese reaching the equivalent point with an alkali having an acid concentration of 0.5 to 0.2N. It is desirable to use a phosphoric acid solution having a pH of 4.5 or less. Manganese dissolution amount is 2000ppm
-40,000 ppm is preferable, and the processing temperature is particularly preferably 95 ° C or more.

The numerical limit of the acid concentration of the chemical conversion treatment liquid is 0.5
Phosphoric acid solutions that are more concentrated than specified have a higher dissolution rate on the metal surface, resulting in poor surface roughness, while solutions that are thinner than 0.2 specified hardly produce free phosphoric acid due to primary dissociation, and grow phosphate crystals. Can not do. Therefore, when the manganese dissolution amount in which the above-mentioned concentration range is suitable is 2,000 ppm or less, the growth of phosphate crystals is slow and only metal dissolution is promoted, and the upper limit is 40,000 ppm, and the manganese ion dissolution amount is saturated. The surface conditioning agent PL-55 (trade name) manufactured by Nippon Parkerizing Co., Ltd., and a chemical conversion treatment solution PF
-MIA, PF-M5 fully satisfies the processing steps for implementing the present invention.

FIG. 2 shows the relationship between the thickness of the phosphate treatment and the time until rusting. As can be seen from FIG. 2, the effective film thickness range for corrosion resistance is 2 to 10 μm, preferably 2 to 10 μm.
５5 μm is desirable. That is, for a thin film of less than 2 μm,
The lower limit of the film thickness is desirably 2 μm or more because the rust-preventive force is reduced. Further, when the film thickness is 10 μm or more, the rust preventive force is improved, but the resistance value is increased. In particular, sufficient corrosion resistance is obtained with a film thickness of 5 μm, which is approximately 25 hours until the occurrence of rust. Therefore, the thickness is preferably 5 μm or less from the viewpoint of suppressing the film thickness in order to suppress the increase in the resistance value and the thickness unevenness.

[Third Embodiment] After inserting a shaft into 50 finished products of the bearing 1 used in the above embodiment and tightening both ends with bolts, a tin grain of 50 μm was formed using a high-speed shot peening device manufactured by Fujiki Sales Co., Ltd. Was used as a medium to form a surface layer (coating) of tin only on the outer diameter portion of the outer ring 3. The thickness of the modified layer (coating) was 1 to 2 μm, and the time until rust generation was 36 hours.

[0029]

As described above, in the rolling bearing for office machines of the present invention, a coating having corrosion resistance and conductivity is formed on a portion which comes into contact with a shaft member and a housing.
A corrosion-resistant bearing that does not require rust-preventive oil while ensuring conductivity for energization and static elimination between the shaft member and the housing can be provided. For this reason, even if the shaft member and the housing are formed of a polymer material for the purpose of reducing the weight, a chemical attack on the housing or the like can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a rolling bearing according to an embodiment according to the present invention.

FIG. 2 is a diagram showing a relationship between plating thickness and corrosion resistance.

FIG. 3 is a diagram showing the relationship between the thickness of a chemical conversion treatment and corrosion resistance.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bearing 2 Inner ring 3 Outer ring 4 Rolling element 5 Coating 6 Shaft member 7 Bearing support part of rotating drum

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor, Satoshi Masada 1-5-50 Kugenuma Shinmei, Fujisawa-shi, Kanagawa F-term in NSK Ltd. (reference) 2H071 CA05 DA08 DA12 DA22 DA24 3J101 AA01 BA53 BA54 DA05 FA08 FA11 GA53 3J103 AA01 DA05 FA06 GA02 GA57 GA58 HA20

Claims (1)

[Claims] 1. An office machine rolling bearing having a rolling element disposed between an inner ring and an outer ring to support a rotating portion, wherein at least one of an inner diameter portion of the inner ring and an outer diameter portion of the outer ring is provided.
A rolling bearing for office machines, wherein a corrosion-resistant and conductive coating is formed.