JPH05240255A - Electrolytic corrosion preventive rolling bearing - Google Patents

Abstract

PURPOSE:To improve creep resisting performance while keeping molding property by forming an insulating coat for a rolling bearing surface from a polyphenylene sulfide resin containing glass fiber and a non-fibrous insulating inorganic filler. CONSTITUTION:A rolling bearing 1 has a plurality circular grooves 4, 5 formed on the surfaces of an inner wheel 2 and an outer wheel 3, and insulating coats 6, 7 formed thereon. The insulating films 6, 7 are obtained by integrally molding a polyphenylene sulfide resin (PPS) containing glass fiber and a non-fibrous insulating inorganic filler into a ring by means of injection molding, and as the inorganic filler, calcium carbonate and glass beads are used alone or in combination. Together with the injection molding, protruding lines 8, 9 to be fitted to the circumferential grooves 4, 5 are provided on the circumferential surfaces of the insulating coats 6, 7. The inorganic filler improves creep resistance similarly to the glass fiber when contained in PPS, but since it is non- fibrous, a reduction in molding property is minimized even if the content is increased. Thus, only the creep resistance can be enhanced without lowering the molding property.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing having an insulating coating to prevent electrolytic corrosion.

[0002]

2. Description of the Related Art Conventionally, in rolling bearings used for electric trains and electric equipment, an insulating coating is formed on the surface of the bearing ring in order to prevent electrolytic corrosion between the bearing ring and the rolling elements. Electrolytic corrosion that flows into the bearing ring from the outside is blocked.

Since such an insulating coating is formed on a bearing ring which is installed between the rotary shaft and the housing with a tight margin, it has low water absorption and does not change the dimensions of the coating.
In order to keep the tightening margin of the bearing constant, it is required to have high creep resistance so as not to reduce the wall thickness.

With respect to these required characteristics, the present applicant has previously proposed an electrolytic corrosion prevention bearing having an insulating coating formed of a polyphenylene sulfide resin (hereinafter abbreviated as PPS) containing glass fiber. (Japanese Patent Application No. 2-78353) In the structure proposed above, by reinforcing PPS having a low water absorption rate with glass fiber, an insulating coating having excellent water absorption characteristics and creep resistance can be formed, and stable electrolytic corrosion prevention performance can be obtained. Can be obtained.

In addition, since PPS has good moldability and the film can be integrally formed by injection molding, there is an advantage that the film can be formed at low cost.

[0006]

However, when the fitting allowance of the bearing and the bearing load are further increased, the outer diameter dimension of the insulating coating changes greatly, and a coating having a large creep resistance is required.

Although such creep resistance can be improved by increasing the content of glass fibers in PPS, on the other hand, the increase in the content of glass fibers causes a problem that the moldability of the coating film is deteriorated. That is, the glass fiber has a function of greatly improving the creep resistance performance of PPS, but the moldability decreases as the content increases, and it becomes impossible to integrally form a film by injection molding. Therefore, the content of the glass fiber needs to be set within a range where injection molding is possible, and there is a limit in improving the creep resistance performance.

The present invention is intended to solve the above-mentioned problems and to provide an anti-corrosion rolling bearing capable of greatly improving creep resistance while maintaining good moldability of an insulating coating.

[0009]

In order to solve the above-mentioned problems, the present invention is one in which an insulating coating is formed of a polyphenylene sulfide resin containing glass fibers and a non-fibrous insulating inorganic filler. Is.

Here, examples of the non-fibrous insulating inorganic filler include calcium carbonate, glass beads, talc, wollastonite and the like, and these are used alone or in combination.

[0011]

When the above inorganic filler is contained in PPS, it improves the creep resistance similarly to glass fiber, but since it is non-fibrous, its formability is lower than that of glass fiber even if its content is increased. Has a small effect on. Therefore, by including the inorganic filler instead of increasing the content of the glass fiber, only the creep resistance can be increased without lowering the moldability.

Further, since the above-mentioned inorganic filler is insulative and has high heat resistance, it does not deteriorate the water absorption characteristics and heat resistance characteristics of PPS and maintains stable electric insulation performance.

The contents of the glass fiber and the inorganic filler must be set within a range that allows the film to be injection-molded and does not lower the creep strength more than necessary. Therefore, the content of the glass fiber is in the range of 25 to 60% by weight ratio to PPS, and the content of the inorganic filler is 10 to 4
The total content of both is set to 40 to 7 by setting it in the range of 0%.
It is preferable to set in the range of 0%.

[0014]

EXAMPLE FIG. 1 shows a rolling bearing of an example. The rolling bearing 1 is formed by forming a plurality of circumferential grooves 4 and 5 on the surfaces of the inner ring 2 and the outer ring 3 and covering them with insulating coatings 6 and 7.

The insulating coatings 6 and 7 are shown in FIG. 1 by injection molding of polyphenylene sulfide resin (PPS) containing glass fibers and a non-fibrous insulating inorganic filler within the above-mentioned weight range. It is integrally formed into such an annular shape. The inorganic filler may be calcium carbonate, glass beads, talc, wollastonite, etc., which may be used alone or as a mixture, and then added to PPS. In addition to the injection molding, the insulating coatings 6 and 7 are provided on the peripheral surfaces thereof with projections 8 and 9 which are fitted into the circumferential grooves 4 and 5 of the inner and outer races 2 and 3.

Although balls are shown as the rolling elements 10, rollers or other shapes of rolling elements may be used.

In order to form the above-mentioned bearing 1, circumferential grooves 4 and 5 are formed on the surfaces of the inner ring 2 and the outer ring 3 of the standard type bearing by machining or the like, and the inner ring and the outer ring are separately formed in the mold. And the coatings 6 and 7 are formed on the peripheral surface by insert injection molding. Alternatively, the surfaces of the inner and outer races 2 and 3 may be covered with the insulating coatings 6 and 7 formed in a ring shape, and may be adhered by paking, coating or the like. In this case, the protrusions 8 and 9 fitted in the circumferential grooves 4 and 5 prevent the coating films 6 and 7 from being displaced in the axial direction, and prevent peeling and floating.

<Experimental example> Outer diameter 170 mmφ, width 32 mm
Samples (a) and (b) in which an insulating coating (film thickness of 1 mm) having the following two types of composition was applied to the rolling bearing of
Formed.

Sample (a): Glass fiber 40 wt%-
Calcium carbonate 15 wt% -PPS 45 wt% Sample (b); Glass fiber 40 wt% -PPS 60 w
t% The samples (a) and (b) described above were left to stand in a housing at a temperature of 110 ° C. for 3000 hours in a state of being press-fitted, and the temporal change in the interference of the bearing during that time was measured. The results are shown in Figure 2.

As shown in FIG. 2, the tightening margin of the sample (a) to which calcium carbonate was added was almost the same as that of the sample (b) to which only glass fiber was added.
A large difference was obtained after 3000 hours compared to the sample (b).

The samples (a) and (b) showed the same moldability and could be easily integrally molded by injection molding. Also, stable electrical insulation performance could be maintained over a long period of time.

[0022]

As described above, according to the present invention, since the PPS resin forming the insulating coating is reinforced with the glass fiber and the non-fibrous insulating inorganic filler, the creep resistance is maintained while maintaining the good moldability of the resin. Can be improved. Therefore, it is possible to provide at low cost an electrolytic corrosion-preventing bearing capable of exhibiting stable bearing performance with no change in bearing interference.

[Brief description of drawings]

FIG. 1 is a sectional view showing a rolling bearing according to an embodiment.

FIG. 2 is a graph showing changes in the interference of bearings in an experimental example.

[Explanation of symbols]

 1 rolling bearing 2 inner ring 3 outer ring 6, 7 insulating coating 10 rolling element

Claims (1)

[Claims] 1. In an electrolytic corrosion-preventing rolling bearing in which an insulating coating is provided on the surface of a bearing ring, the insulating coating is formed of polyphenylene sulfide resin containing glass fiber and a non-fibrous insulating inorganic filler. A rolling bearing that prevents electric corrosion.