JP2004270747A - Rolling bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing device with low dust generation that has less variation in dust generating amount for each device and is suitable for use in a clean room or the like. <P>SOLUTION: In the rolling bearing device, two sealed type rolling bearings 2 and 2 are incorporated coaxially in a housing 1. These two rolling bearings 2 and 2 are disposed so that the pole sections (substrate) 104a of respective crown type retainer 104 direct to the outside in the axial direction. In this constitution, the rolling bearing device suppresses dust generation as the entire rolling bearing device and can reduce variation in dust generating amount. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bearing device in which two rolling bearings are coaxially arranged, and more particularly, to a long-life rolling bearing device which generates a small amount of dust and is suitable for use in a clean room or the like.
[0002]
[Prior art]
Equipment used in an environment where a required degree of cleanness is required in the atmosphere, such as in a clean room, is required to generate little dust from bearings. Conventionally, rolling bearings used in equipment for such applications adopt a ceramic material for the bearing ring and rolling elements and use grease-free bearings or, instead of grease, replace the raceway surface and rolling elements. BACKGROUND ART A bearing having a surface coated with a soft metal such as gold, silver, lead, or copper, or a solid lubricant such as carbon or molybdenum disulfide is used. (See, for example, Patent Document 1 or Patent Document 2).
[0003]
However, when a bearing that does not use the above-described grease or a solid lubricated bearing is used for a high-speed rotating device such as a spin dryer in a semiconductor manufacturing process, the life is inevitably shortened as compared to a bearing that uses a grease. There was a problem. Therefore, for equipment that requires a long service life in such a clean environment, grease of a type that generates relatively little dust should be used for the lubricant, and the opening of this bearing should be made non-dust-free. A hermetic rolling bearing sealed by a contact rubber seal is employed.
[0004]
FIG. 5 is a sectional view showing the structure of this type of sealed rolling bearing.
The rolling bearing mainly includes an inner race 101 having an inner raceway groove 101u formed therein, an outer race 102 having an outer raceway raceway groove 102u formed therein, and a plurality of balls 103 arranged in an annular space between the inner and outer races. It is configured as These balls 103 are rotatably held at predetermined intervals in the circumferential direction between the raceway grooves of the inner and outer rings by a crown-shaped retainer 104 having a plurality of pockets 104p.
[0005]
The crown type retainer 104 is formed asymmetrically in the axial direction as illustrated in an external view of FIG. 6, and is provided at a constant pitch in the circumferential direction on one side in the axial direction of the annular base (the column 104a). The pocket 104p is formed. Each pocket 104p is substantially along the surface of the ball 103 by a concave portion 104q formed at a predetermined position at the base of the pillar portion 104a and one side surface 104r of a pair of claw portions 104b protruding at a constant height on both sides thereof. It is formed in a concave spherical surface.
[0006]
In addition, the annular space of the rolling bearing is filled with a lubricant (not shown) such as grease using fluorine-based oil as a base oil, and a small amount of dust is generated. The grease is sealed by a rubber seal 105 to prevent the grease from leaking to the outside.
[0007]
When the rolling bearing having the above structure is used for a device such as a spin drier, as shown in FIG. 7, two rolling bearings 2 and 2 are arranged coaxially within the housing 1 with a distance therebetween. The rolling bearing device that supports the rotating shaft 3 of this device is integrally incorporated.
[0008]
[Patent Document 1] Japanese Patent Application Laid-Open No. 7-233818 [Patent Document 2] Japanese Patent No. 30029257 [0009]
[Problems to be solved by the invention]
By the way, in a device using the above-described rolling bearing device, the amount of dust generated varies from device to device or from bearing device to device, and even if grease with less dust is used, a sufficient dust generation suppressing effect cannot be obtained. There was a case. In addition, in an environment where cleanliness is required, such as a clean room, a rolling bearing device that generates a large amount of dust may affect the yield of products manufactured in that environment by mixing dust as an impurity. It is also possible that
[0010]
The present invention has been made to address the above-described problems, and has as its object to provide a low-dust-generating rolling bearing device that has a small variation in the amount of dust generation for each device and is suitable for use in a clean room or the like. I have.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 provides an inner ring using a crown-shaped retainer having a pocket formed by an annular column and a claw projecting axially from the column. In the annular space between the inner ring and the outer ring, a plurality of balls are rotatably held, and the grease filled in the annular space is sealed by seal members disposed at both ends of the annular space. In a rolling bearing device in which two rolling bearings are coaxially incorporated in a housing, the two rolling bearings respectively have the column portions and the shaft of the housing such that pocket opening sides of a crown type retainer face each other. It is characterized by being arranged facing outward in the direction.
[0012]
The present invention focuses on the relationship between the direction of the rolling bearing and the total amount of dust generation in a rolling bearing device in which two rolling bearings are arranged coaxially, and defines the intended mounting direction of the bearing with respect to the housing. It is to achieve the purpose.
[0013]
Normally, when assembling a sealed rolling bearing using a crown type retainer as described above, the grease G is filled toward the opening of the pocket 104p of the crown type retainer 104 as shown in FIG. . When this rolling bearing rotates, the grease G forms an oil film between the ball 103 and each of the raceway grooves 101u and 102u, and as shown in FIG. 9, the inner surface of the rubber seal 105 on the pocket opening side, It is known that it stays on the outer peripheral surface of the inner ring 101 and the outer peripheral surface of the outer ring 102.
[0014]
Therefore, the present inventors have focused on the relationship between the direction of the crown-shaped retainer inside the bearing after the assembly into the housing and the amount of dust generation, and as a result of earnest study, the pocket opening side of the crown-shaped cage in the bearing, It has been found that the dust generated from the bearing device can be suppressed by directing it toward the inside of the housing.
[0015]
That is, according to the rolling bearing device of the present invention, by incorporating each of the two rolling bearings such that the pillar portion of the crown type retainer faces outward in the axial direction of the housing, a pocket having a relatively large amount of dust is generated. The opening side faces the inside of the housing to each other, so that the generation of dust as the whole rolling bearing device can be suppressed, and the variation in the amount of generated dust can be reduced.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing the structure of the rolling bearing device according to the embodiment of the present invention. The structure of each rolling bearing used in this embodiment is the same as that of the conventional example shown in FIG. 5, and therefore detailed description is omitted.
[0017]
This rolling bearing device is formed by incorporating two hermetically sealed rolling bearings 2 and 2 on the inner periphery of a substantially cylindrical housing 1. These two bearings are arranged apart from each other in the axial direction, and a rotating shaft 3 such as a spin dryer is inserted through the inner periphery of the bearings.
[0018]
The feature of this bearing device is that, as shown in FIG. 1, the two rolling bearings 2 and 2 fitted on the inner periphery of the housing 1 are arranged such that the column portions 104a of the crown type retainer 104 face outward in the axial direction. It is a point that is arranged. That is, these bearings are incorporated such that the opening sides of the pockets 104p of the crown-shaped retainer 104, which are highly likely to generate dust, face each other inward in the axial direction.
[0019]
With the above configuration, the rolling bearing device according to the present embodiment can suppress the generation of dust as a whole of the rolling bearing device, and can reduce the variation in the amount of generated dust.
[0020]
In addition, the material and shape of the crown type retainer and the seal member in each rolling bearing are not limited to the examples in the above embodiments. However, a non-contact type rubber seal that does not generate dust is suitable for the seal member.
[0021]
The grease filled in the annular space may be appropriately selected according to the environment in which the grease is used. However, when chemically stable grease with little dust generation is required, it is desirable to use a grease using a fluorine-based oil as a base oil.
[0022]
Next, in order to confirm the effect of the rolling bearing device in the above embodiment, a comparison was made between an example employing the bearing arrangement of the present invention and an arrangement in which the pocket opening side of the crown type retainer faces the outside of the housing. An experimental result of actually measuring the amount of generated dust will be described using an example.
[0023]
FIG. 2 is an explanatory diagram showing an outline of the measuring device used in this experiment.
Reference numeral 12 in FIG. 2 denotes a bearing device to be tested, which is disposed in a cover (made of acrylic) 21 having a dust collection tube 22. The bearing device 12 has two sealed rolling bearings 11a and 11b mounted thereon, and is fitted in a rotating shaft 14 connected to a drive source such as a motor, and is axially moved by a coil spring 13 in a axial direction. A load is applied. The dust collection tube 22 is connected to a dust generation number measuring device (particle counter) 23, and the measurement result is recorded on a recorder or the like. The entire measuring apparatus is placed in a clean bench, and clean air is always supplied from above in the figure.
[0024]
The rolling bearing 11 used in the test has a nominal number of 6003 (φ17 × φ35 × φ10). The inner and outer rings and balls are made of bearing steel, and the retainer is a crown made of polyamide resin. In addition, a non-contact type made of nitrile rubber is used for the seal member. As the grease sealed inside the bearing, grease A using a general hydrocarbon-based synthetic oil as a base oil and grease B using a fluorine-based oil which is considered to generate relatively little dust are used. Was.
[0025]
The test was performed on the following four types of rolling bearing devices.
{Circle around (1)} Example 1: Two bearings each using grease A (hydrocarbon) are arranged such that the pillars of the crown-shaped cage face the outside of the housing.
{Circle around (2)} Comparative Example 1: Two bearings each using grease A (hydrocarbon) are arranged such that the pocket openings of the crown type retainer face the outside of the housing.
{Circle over (3)} Example 2: Two bearings each using grease B (fluorine-based) are arranged such that the pillars of the crown type retainer face the outside of the housing.
{Circle around (4)} Comparative Example 2: Two bearings each using grease B (fluorine-based) are arranged such that the pocket openings of the crown type retainer face the outside of the housing.
[0026]
Test condition atmosphere: In the air, in a clean bench (Class 1)
Environmental temperature: Room temperature load: Axial load (49N)
Rotation speed: 2000 rpm
Measurement: The amount of dust generated at 10-minute intervals was recorded for dust having a particle diameter of 0.1 μm or more after the start of rotation.
In addition, the amount of dust per measurement is an average value of 15 measurements.
[0027]
FIG. 3 shows the measurement results of the bearing device using grease A (hydrocarbon), and FIG. 4 shows the measurement results of the bearing device using grease B (fluorine).
[0028]
As is clear from these graphs, in the bearing device of the embodiment to which the present invention is applied, dust generation of the entire bearing device is significantly reduced as compared with the comparative example regardless of whether grease A or grease B is used. ing. In addition, it can be seen that there is little increase / decrease in the number of times of measurement and the variation in the amount of generated dust is reduced.
[0029]
In addition, the material constituting the bearing ring and the ball is not limited to the bearing steel in the above embodiment, and may be appropriately selected according to the environment in which the bearing is used. For example, the bearing may be made of stainless steel or a ceramic material in order to increase the corrosion resistance of the bearing.
[0030]
【The invention's effect】
As described in detail above, according to the rolling bearing device of the present invention, by combining each of the two rolling bearings such that the column portion of the crown type retainer faces outward in the axial direction of the housing, the rolling bearing is provided. The generation of dust as a whole apparatus is suppressed, and the variation in the amount of dust can be reduced.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a structure of a rolling bearing device according to an embodiment of the present invention.
FIG. 2 is an explanatory view of a test device used for measuring the amount of generated dust of a rolling bearing device.
FIG. 3 is a graph showing a measurement result of a dust generation amount when a hydrocarbon grease A is used for a rolling bearing.
FIG. 4 is a graph showing a measurement result of a dust generation amount when fluorine grease B is used for a rolling bearing.
FIG. 5 is a sectional view showing the structure of a conventional sealed rolling bearing.
FIG. 6 is an external perspective view of a crown type cage.
FIG. 7 is a schematic sectional view showing a configuration example of a conventional rolling bearing device.
FIG. 8 is an explanatory view showing a filling position of grease G in a conventional sealed rolling bearing.
FIG. 9 is an explanatory diagram showing a retaining position of grease G during rotation in a conventional sealed rolling bearing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 2 Rolling bearing 3 Rotating shaft 11a, 11b Rolling bearing 12 Bearing device 13 Coil spring 14 Rotating shaft 21 Cover 22 Dust collection tube 23 Particle generation number measuring device 101 Inner ring 101u Inner ring side raceway groove 102 Outer ring 102u Outer ring side raceway groove 103 Ball 104 Crown type retainer 104a Column (base)
104b claw 104p pocket 104q recess 104r side 105 rubber seal

Claims (1)

A plurality of balls can roll freely in an annular space between an inner ring and an outer ring by a crown-shaped retainer having a pocket formed by an annular pillar portion and a claw portion projecting axially from the pillar portion. A rolling bearing device which holds two rolling bearings, which are sealed at both ends of the annular space and seals grease filled in the annular space inside the housing, coaxially in the housing. At
The rolling bearing device, wherein the two rolling bearings are arranged such that the column portions face outward in the axial direction of the housing, respectively, such that pocket opening sides of the crown type cage face each other.

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