JPS6376908A - Rolling bearing - Google Patents

Abstract

PURPOSE:To prevent easily and securely the occurrence of fretting corrosion in which abrasion powder adheres to minute clearances, by forming a film consisting of fluorine-contained polymers at least on one surface out of inner and outer circumferential surfaces of inner and outer rings and respective end surfaces and the like in a rolling bearing. CONSTITUTION:At least on one surface out of the outer circumferential surface of an outer ring, the inner circumferential surface of an inner ring, the end surfaces of the outer ring, and the end surfaces of the inner ring in a rolling bearing, a film consisting of fluorine-contained polymers is formed. In this case, as for the fluorine-contained polymers, polyfluoroalkyl-polymers or fluoropolyether-polymers, or the like are used. And the polyfluoroalkyl-polymers are to be polymers having a prescribed polyfluoroalkyl group. Further, the fluoropolyether-polymers make the unit expressed by the general expression of-CxF2x-O-, in which x is an integer from 1 through 4, the principal structural unit, and are to be polymers whose mean molecular weight is 1000 to 50000. Thus, the occurrence of fretting corrosion can be easily and securely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rolling bearing, and particularly to a rolling bearing that prevents fretting corrosion.

[Conventional technology and its problems]

In rolling bearings, for design reasons, a small gap is provided between the outer ring and the housing or the shaft fitted into the inner ring. When the material of the housing or inner ring of such rolling bearings is metal, when subjected to vibration or repeated rocking with small amplitude, fretting corrosion, where rust-like wear particles are often generated and adhered in the minute gaps mentioned above, occurs. There is.

In order to prevent Frenching corrosion, a method is generally used to apply an oil with medium viscosity or a grease with high consistency and good fluidity before assembly. However, this method is not only undesirable because it complicates the assembly process, but also because fluid oil or grease may run out during use, it is difficult to completely prevent flexo corrosion. is difficult and requires mechanical preventive measures.

Another method is to form a wear-resistant coating by metal plating or plasma coating. However, this method is not only undesirable due to its complicated process, but also makes it difficult to control the film thickness, and requires post-processing for parts that require high precision, such as the outer diameter of the outer ring and the inner diameter of the inner ring, making it a realistic method. I can't say that.

Furthermore, there is a method of coating tetrafluoroethylene resin with polyimide, polyamide, epoxy resin, etc. as a binder, but this method requires post-processing because the film is too thick, or the dimensions are set by subtracting the film thickness. Since it is necessary to prepare a dedicated bearing for coating, this method is also not a desirable method.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a rolling bearing that can easily prevent the occurrence of frenoting corrosion.

[Means for solving problems]

In order to solve the above problems, the present invention employs means for forming a thin film made of a fluoropolymer on at least one of the outer circumferential surface of the outer ring, the inner circumferential surface of the inner ring, the end surface of the outer ring, and the end surface of the inner ring. This is what I did. The details will be described below.

The fluorine-containing polymer in this invention is a polyfluoroalkyl polymer, a fluoropolyether polymer, or the like. The polyfluoroalkyl polymer is, for example, CFz(CF2)t-1H(CFt)s-1ChCI(
Ch) ++-1 is a polymer having a polyfluoroalkyl group, and the fluoropolyether polymer is a CX
F! The main structural unit is a unit represented by the general formula X-0- (, is an integer of 1 to 4), and the average molecular weight is 1000 to
It is a polymer of 5oooo. Such fluoropolymers contain functional groups that have a high affinity for bearing materials, such as epoxy groups, amino groups, carboxyl groups, hydroxyl groups, mercapto groups, isocyanate groups, sulfone groups, and ester groups. is preferable, and specifically, the following can be mentioned as an example. That is, C*F+,C0OH,C,F+FCJ*OH%CsF+
tCJ*SH1GO ChF+3CzHaOCNH(Cut)JCO10CN
(CHz) JH(:(CFz) aCNH(CL)
4NCO1CJ+ffSCIbCHxOC(CHz)
sNHg, C1oFz+C0N1(CtH40H,
C+oFt+5OsH.

HooC-CFzO+CzFnOMCFzO)acFz
cOOH.

HOOC-Ch04CFz-CF-OhdChOhCF
s, C.F.

CI*00C-CFtO+CzFsO product CFzOhCF
zCOOCHs, HOCHz-CFzMCJaO)r
(CFgO)llCFt-CHzOH.

ChO(Ch-CF-OhCFyo-C-CFff,
ICF, .

etc., where m and n are integers.

Such a fluorine-containing polymer may be used alone, but in that case it is preferable to use one containing an epoxy group or an isocyanate group, and when using an epoxy group, amines,
It is advisable to add an acid anhydride or the like to cause the epoxy groups to react with each other, and when using an isocyanate group alone, it is advisable to add an isocyanate trimerization catalyst such as a tin compound.

In addition, two or more types of fluorine-containing polymers may be used in combination, but in that case, one containing an epoxy group and one having at least one type of group such as an amino group, a carboxyl group, a hydroxyl group, or a mercapto group may be combined. , or one containing a carboxyl group and at least one of an amino group and a hydroxyl group
A combination of two types of groups, or a combination of incyanate groups and at least one type of group such as a hydroxyl group, an amino group, a mercapto group, or a carboxyl group. It is desirable to make the polymers react with each other to increase the molecular weight of the polymer to obtain a film with excellent wear resistance.

Furthermore, an organic compound having a functional group that causes a chemical reaction with each functional group may be added to the fluorine-containing polymer having these functional groups to increase the molecular weight. Examples include a combination of adding ethylene glycol, diaminodiphenylmethane, etc. to a fluoropolymer.

The above-mentioned fluoropolymers themselves exhibit considerable affinity for the surface of bearing materials, but depending on the type of mating material, they may not necessarily exhibit sufficient adhesion strength. In such cases, it is preferable to interpose a thin film (called a brimer) that has an affinity for both the coating and the mating material, and one example of such brimer is polymethyl methacrylate. As a component, a graft polymer having a methyl methacrylate unit or a hydroxyl ethyl methacrylate unit as a main component can be mentioned.

The method for applying the above-mentioned fluorine-containing polymer may be any ordinary coating method and is not particularly limited, but for example, the fluorine-containing polymer may be dissolved in a suitable solvent and applied (including spraying, dipping, etc.). and then evaporate the solvent <, yi
It is also possible to increase the molecular weight of the film-forming components by heating after forming the film.

It is desirable that the thin film coating the bearing of the present invention has a thickness of 4 μm or less, preferably 3 μm or less, so as not to impair the dimensional accuracy of the bearing.

〔Example〕

The raw materials used in the Examples and Comparative Examples are as follows. In addition, in order to simplify the raw material family name or structural formula, we will use the numbers (■ to ■) attached to each raw material.
The blending ratio is expressed as % by weight.

■Polyfluoroalkyl polymer (contains epoxy group) ■Polyfluoroalkyl polymer (contains amino group) ■Perfluoropolyether polymer (contains isocyanate group) (average molecular weight approximately 2000), ■Polyfluoroalkyl polymer (contains hydroxyl group) IOC) 12-CF20&F40h (CFzOhCh
-CHzOH (average molecular weight approximately 2000), ■Ethylene glycol ■Dibutyltin dilaurate ■Turbine oil (manufactured by Idemitsu Co., Ltd., Daphne Svar Turbine Oil 56) [Examples 1 to 4] The raw materials shown in Table 1 were adjusted to a concentration of 3%. Adjust the coating solution by diluting it with the solvent in the table so that the inner diameter is 4mm and the outer diameter is IQm.
m, outer ring of a rolling bearing with a tolerance of -3 to -2 μm (material
5US440C) was immersed. After immersion, the outer ring was taken out, dried at 70°C for 1 hour, and then heated at 150°C for 2 hours. After that, I assembled the bearing, filled it with grease, and ran a tight shaft through the inner diameter. Inner diameter 10mm, tolerance O~-15μ
m.

A bearing was inserted into an axle box made of aluminum ADC-12 to fix the axle. Table 1 summarizes the results of examining the occurrence time of flexo corrosion on the outer circumferential surface of the outer ring by periodically applying vibrations of 20 G and 50 to 200,082 to the axle box.

In addition, the time taken for fretting corrosion to occur was measured at 200
It was canceled in time.

[Comparative Example 1] A test similar to Example 1 was conducted except that nothing was applied to the bearing. The results are summarized in Table 1.

[Comparative Example 2] The same test as in Example 1 was conducted except that the turbine oil (■) was applied to the outer ring of the bearing. The results are summarized in Table 1.

As is clear from Table 1, fluffing corrosion occurred in Comparative Example 1 in 40 hours, and in Comparative Example 2 where lubricating oil was applied, it also occurred in 85 hours, which was inferior to any of the Examples. .

Note that under the same conditions as Example 1, the average of SUS, 440C (
A thin film was formed with a surface roughness (Ra=0.2), and the film thickness was measured using a stylus type surface roughness meter, and found to be 1.1 μm.

Table 1 [Effects of the Invention] As stated above, the rolling bearing of the present invention can prevent the occurrence of flexo corrosion.
It can withstand operation under conditions where fretting corrosion occurs.

Furthermore, since the thin film of the present invention is a thin film, it does not require a bearing whose dimensions are specially adjusted for application.

Therefore, it can be said that the significance of this invention is extremely large.

Claims (1)

[Claims] A rolling bearing characterized in that a thin film made of a fluoropolymer is formed on at least one of an outer circumferential surface of an outer ring, an inner circumferential surface of an inner ring, an end surface of an outer ring, and an end surface of an inner ring.