JP2001227548A - Cage for rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cage for a rolling bearing capable of maintaining excellent silence over a long period when applied to the rolling bearing. SOLUTION: The thickness of an amorphous layer of a surface of this cage for the fiber reinforced resin rolling bearing is set not more than 30 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cage for a fiber-reinforced resin rolling bearing, and more particularly to a hard disk drive (hereinafter abbreviated as HDD), a video tape recorder (hereinafter abbreviated as VTR), and a digital audio tape. The present invention relates to a rolling bearing retainer suitably used for a rolling bearing used for a rotation supporting portion of a recorder (hereinafter, referred to as DAT), a laser beam printer (hereinafter, referred to as LBP), or the like.

[0002]

2. Description of the Related Art Although the computer-related industry is a business with a short history as compared with other industrial fields, the speed of technological innovation is high. In particular, HDDs have a short existence period for one model, and new models have been developed one after another with high precision and compactness by introducing new technology.

[0003] Against this background, demands for rolling bearings used in information devices such as HDDs have been increasing year by year, and demands for higher speed and quieter operation have been increasing. To be maintained over time. On the other hand, in conventional rolling bearings used for HDDs, VTRs, DATs, LBPs, and the like, a plastic cage represented by a fiber-reinforced polyamide resin is mainly used.

[0004]

However, in a rolling bearing provided with a retainer made of a fiber-reinforced plastic as described above, the rolling bearing has to be provided at the time of manufacture as the operating conditions of the rolling bearing are increased. Although the quietness cannot be maintained for a long time (sound rise), the appearance rate tends to increase, and the cause has not been sufficiently elucidated.

[0005] In order to elucidate the cause, an analysis of foreign matters remaining inside the rolling bearing that caused such a rise in sound revealed that many glass fibers were added for the purpose of improving the strength of the plastic cage. It became clear that it was included. Glass fiber is low in hardness, so it does not repeatedly damage the rolling surface of the rolling bearing and bring it to a rough surface, but it is crushed when it is caught between the rolling element and the raceway. It is presumed that the above-mentioned sound rise is caused by generating a popping sound together with the sound. Further, the following is presumed as a reason why the glass fibers drop from the cage and are discharged into the rolling bearing.

When a plastic cage is molded by an injection molding method or the like, a high-temperature resin comes into contact with a low-temperature mold and is rapidly cooled. An amorphous layer 1 called a skin layer is formed near the mold, that is, on the surface of the plastic cage. FIG. 2 is a partial cross-sectional view showing the internal structure of the plastic cage manufactured by the injection molding method. The shear fluidized bed 2 in which the shearing force acts most on the outer layer of the inner crystalline layer 3 is shown. An amorphous layer 1 called a skin layer is formed on the outer layer.

The thickness of the amorphous layer tends to increase as the difference between the resin temperature during molding and the mold temperature increases. This is because the higher the cooling rate when the resin comes into contact with the mold (the faster the resin is cooled), the more difficult it is to crystallize. Since the skin layer is amorphous, its properties are different from those of the inside of the cage which is crystalline, and it is inferior in chemical resistance and abrasion resistance. That is, since it has the property of easily swelling with an organic solvent, a lubricating oil, or the like, the swelling reduces the hardness and makes it easy to wear. As a result, when used as a cage for a rolling bearing, depending on the operating conditions (type of lubricating oil, load, rotation speed, etc.), swelling and abrasion of the skin layer may occur, exposing the glass fibers to the surface, and rolling The glass fibers may be released inside the bearing. When this glass fiber is caught between the rolling element and the bearing ring, it is presumed that a plosive sound is generated along with the pulverization to cause a sound rise.

[0008] In short, as the thickness of the amorphous layer on the surface of the cage is larger, the glass fibers are more likely to be exposed on the surface due to the wear of the amorphous layer, and as a result, the rolling bearing has a more adverse effect on quietness. It is. Therefore, the present invention solves the problems of the conventional fiber-reinforced plastic rolling bearing cage as described above, and when applied to a rolling bearing, a rolling bearing that can maintain excellent quietness for a long period of time. An object of the present invention is to provide a retainer for use in a vehicle.

[0009]

In order to solve the above problems, the present invention has the following arrangement. That is, the rolling bearing of the present invention is characterized in that the thickness of the amorphous layer on the surface is 30 μm or less in the roller bearing cage made of fiber reinforced resin. If the thickness of the amorphous layer, which is inferior in chemical resistance and abrasion resistance, is small, the portion that disappears due to swelling and abrasion when the rolling bearing is rotated decreases,
The fibers are less likely to be exposed on the surface of the rolling bearing retainer, and therefore less likely to be released into the rolling bearings. Therefore, the rolling bearing can maintain excellent quietness for a long time.

[0010] The thickness of the amorphous layer is governed by the speed at which the cage for rolling bearings is cooled during molding, and tends to be thinner as the cooling speed is lower. For example, if the molding method is an injection molding method, it is determined by the difference between the temperature of the injected resin and the mold temperature,
The thickness of the amorphous layer is 30 μm or less if the difference in the temperature is less than about 160 ° C., although it varies depending on conditions such as the type of the resin, the type and the content of the fiber.

In the present invention, the thickness of the amorphous layer is 3
It needs to be 0 μm or less. When the diameter exceeds 30 μm, a portion which disappears due to swelling or abrasion when the rolling bearing is rotated increases, so that there is a high possibility that the fibers are released into the rolling bearing to cause an acoustic rise. In addition, the fact that the amorphous layer has a thickness exceeding 30 μm means that the cooling rate is high (rapid cooling), so that the rolling bearing retainer is deformed during molding, Harmful stress may remain on the surface of the cage, which is not preferable.

However, if the difference in temperature is too small, that is, if the cooling rate is too slow, the thickness of the amorphous layer is reduced, but the fibers are arranged near the surface of the cage for rolling bearings. Is more likely to occur, and the probability of occurrence of a problem is rather increased. Therefore, the thickness of the amorphous layer is more preferably 10 to 30 μm.

The resin constituting the fiber-reinforced resin used in the cage for a rolling bearing of the present invention includes polyamide resin such as nylon and polyetheretherketone resin (PE).
EK), polyoxymethylene resin (POM), polybutylene terephthalate resin (P
BT), linear polyphenylene sulfide resin (L-
Crystalline resin such as PPS).

[0014] The type of fiber is not particularly limited as long as it imparts sufficient strength to the roller bearing cage. For example, glass fiber, carbon fiber, aramid fiber, various whiskers and the like can be mentioned. The content of the fiber in the fiber reinforced resin is appropriately selected in consideration of the moldability, the assemblability, and the like in addition to the strength of the cage for the rolling bearing. Usually, it is 5 to 40% by weight.

Further, the type of the cage for the rolling bearing is not particularly limited, and examples thereof include a crown type cage, a cage type cage, a single type cage, a waveform type cage and the like.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rolling bearing cage according to the present invention will be described in detail below. Using a glass fiber reinforced polyamide resin as a material, a crown type retainer was formed by an injection molding method. At that time, the amorphous layer on the surface of the cage was adjusted to 20 μm by adjusting the resin temperature and the mold temperature during molding.

(Examples and Comparative Examples) Next, in addition to the above-mentioned polyamide crown retainer, the amorphous layer is adjusted to 5 to 50 μm by adjusting the resin temperature and the mold temperature during molding. A cage was prepared. Then, using the cages, the following bearings were manufactured, and acoustic tests were performed on 1000 bearings under the following conditions to calculate a rejection rate. The results are shown in the graph of FIG. (1) Types of bearings Single row deep groove ball bearings, non-contact rubber seals (V type), nominal number 695, inner diameter 5 mm x outer diameter 13 mm x width 4 mm, rolling element diameter 2.0 mm (2) Grease ester base used Oil to which lithium 12-hydroxystearate was added as a thickener was used. Note that the consistency is defined by N defined in JIS K2220.
o. It was set to 3.

The amount of grease to be filled is 15
vol%, and sealed so as to be in contact with the surface of the cage. The bearing space is a value obtained by subtracting the volumes of the rolling elements and the retainer from the volume of the space formed by the outer ring, the inner ring, and the non-contact rubber seal of the single-row deep groove ball bearing. (3) Acoustic test conditions Bearing rotation speed: 7200 rpm (outer ring rotation) Axial load: 20 N Ambient temperature: 80 ° C. Criteria: Acoustic measurement of the bearing is performed using an Anderon meter, and the bearing anderon value immediately after the grease is sealed The case where the difference (magnitude of rise) between the (initial anderon value) and the bearing anderon value after 5000 hours of rotation was 0 to 1.0 was judged as acceptable, and 1.1 or more was judged as unacceptable. Note that this criterion was set to be much harsher than that of the completed bearing.

As can be seen from FIG. 1, the bearing in which the amorphous layer on the surface of the cage had a thickness of 30 μm or less, particularly 10 to 30 μm, had a low rejection rate and had excellent acoustic durability.
On the other hand, a bearing having a diameter exceeding 30 μm had a high rejection rate and was inferior in acoustic durability. This rejection rate is defined as the ratio of the number of rejections when the number of tests n = 1000.

As described above, the bearing to which the cage for a rolling bearing according to the present embodiment is applied can maintain excellent quietness for a long period of time, and the appearance rate of the bearing that causes an acoustic rise is low. Note that the present embodiment is an example of the present invention, and the present invention is not limited to the present embodiment.

For example, in this embodiment, an example in which a crown type cage is manufactured using a polyamide resin as a resin and a glass fiber as a fiber has been described. , And the type of the retainer are not limited to those described above, and may be, for example, those described in the section of means for solving the problem.

Although a single row deep groove ball bearing has been described as an example of the rolling bearing, the retainer for a rolling bearing of the present invention can be applied to various other types of rolling bearings. For example, tapered roller bearings, cylindrical roller bearings, spherical roller bearings, angular contact ball bearings, and the like. Further, the material of the rolling element is not particularly exemplified, but may be steel or ceramic.

[0023]

As described above, in the cage for a rolling bearing of the present invention, since the thickness of the amorphous layer on the surface is small, the fibers are less likely to fall off from the surface when applied to a rolling bearing. Is less likely to cause a sound rise. Therefore,
It is possible to maintain the quietness of the rolling bearing for a long period of time, and the appearance rate of a bearing that causes an acoustic rise is low.

[Brief description of the drawings]

FIG. 1 is a graph showing the correlation between the thickness of an amorphous layer of a cage and the acoustic characteristics of a single-row deep groove ball bearing using the cage.

FIG. 2 is a sectional view showing an internal structure of the cage.

[Explanation of symbols]

 Reference Signs List 1 amorphous layer 2 shear fluidized bed 3 crystalline layer

Claims (1)

[Claims] 1. A rolling bearing cage made of fiber reinforced resin, wherein the thickness of the amorphous layer on the surface is 30 μm or less.