JPH0627857Y2 - Rolling bearing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a non-lubricated rolling bearing used in fields such as the food industry, the semiconductor industry, and the like, where high cleanliness in the working chamber is required.

<Prior Art> In a rolling bearing that does not use a lubricant such as oil or grease, it is necessary to use a solid lubricant in order to reduce friction between the bearing ring and the rolling elements.

By the way, conventionally, a non-lubricated rolling bearing shown in FIG. 3 is known. This rolling bearing has an inner ring 1,
An outer ring 2, a steel ball 3, and a retainer 5 for holding the steel ball 3 are provided, the inner ring 1 and the outer ring 2 are made of a metal having no self-lubricating property, and the retainer 3 has a self-lubricating property. It is made of fluororesin. Then, this fluororesin is sequentially transferred to the steel ball 3 and the inner and outer rings 1 and 2 in accordance with the rotation to form a transfer film to perform a lubricating action.

However, in a rolling bearing made of a combination of the above materials, it takes time for the fluororesin of the cage 5 to transfer to the surface of the steel ball 3 in the initial stage of operation. There is a problem that the lubrication action between the balls 3 is not performed well.

On the other hand, as another conventional example, there is known one in which the inner and outer races, the cage, and the sphere are all made of the same material (Japanese Patent Laid-Open No. 51-51980).
-110152 publication). This material is a sinterable carbon material obtained by mixing carbon fibers as needed in a raw material in which graphite, carbon black, coke, etc. are mixed in an appropriate amount, and has self-lubricating properties. It is certain that the bearing will get high lubricity.

However, the hardness obtained by this material is 30 to 120 Shore hardness (equivalent to Vickers hardness Hv = 207).
And low, unable to withstand high loads.

<Object of the Invention> Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a rolling bearing having good non-lubrication performance and capable of withstanding a high load.

<Structure of Device> In order to achieve the above object, the rolling bearing of the present invention is formed of a bearing ring made of bearing steel or stainless steel, a rolling element made of carbon, and a fluororesin holding the rolling element. A cage is provided, and the hardness of the rolling element is 1.5 times or more the hardness of the bearing ring.

<Operation> In the initial stage of operation, the carbon forming the rolling element provides a lubricating action between the rolling element and the race. Then, as the rotation advances, the fluororesin of the cage is scraped by contact with the rolling elements, and this fluororesin is transferred to the surface of the rolling elements,
A transfer film is formed. The fluororesin that has transferred to the rolling elements further transfers to the race of the bearing ring, and lubrication between the bearing ring and the rolling element is performed.

At that time, since the hardness of the rolling element made of carbon is 1.5 times or more the hardness of the bearing ring made of bearing steel or stainless steel, the rolling element rolls in the bearing ring without wear.

<Embodiment> Hereinafter, the present invention will be described with reference to an illustrated embodiment.

FIG. 1 is a front view of a ball bearing 10 which is an example of the rolling bearing of the present invention. 11 and 12 are inner and outer rings serving as race rings, and 13 is a race 11a of the inner ring 11 and a race 12a of the outer ring 12 respectively. A ball as an example of a rolling element that revolves while rotating on the axis, and 14 is a retainer for holding the plurality of the balls 13 at regular intervals.

The inner ring 11 and the outer ring 12 are formed of bearing steel or stainless steel having no self-lubricating property. On the other hand, the ball 13 is made of carbon having self-lubricating property, and the cage 14 is also made of fluororesin having self-lubricating property. The fluororesin of the cage 14 is transferred to the sphere 13 and further to the inner and outer rings 11 and 12.

Inner and outer rings 11,1 made of bearing steel or stainless steel of this embodiment
The Vickers hardness (Hv) of 2 is 700, the Hv of the carbon sphere 13 is 1700, and both have sufficient strength, and the sphere 13 has a higher hardness than the inner and outer rings 11, 12. Therefore, it can withstand a high load. The relationship between the hardnesses of the two is Hv (sphere) ≧ 1.5 Hv (inner and outer rings). This is for the following reasons.

That is, the ball 13 has a longer time under load than the inner and outer rings 11 and 12, and the contact surface pressure is high because the curvature is small. Therefore, when the Hv value of the ball 13 is smaller than the above range, the wear of the ball 13 progresses and the abrasion powder is discharged, so that the ball 13 can be used only under an extremely low load. In other words, when a large amount of wear powder is discharged, the lubricating performance due to the transition inherent in the fluororesin may be canceled by the large amount of wear powder.
The progress of wear in No. 3 cannot be stopped.

Further, as shown in FIG. 2 (a), the cage 14 has an opening 15 on its side surface and has a crown shape. Thus, by providing the retainer 14 with the opening 15, the retainer 14 does not restrain the sphere 13 excessively, and flexibility for following various movements of the sphere 13 is obtained. , The ball 13 is always guided well, and the retainer 14
Optimally supplies the transfer film from the sphere to the sphere 13. Figure 2 (b) shows
Since the opening 15 is formed by the projection for enveloping the ball 16, it is more flexible and more flexible.

Ball bearing 10 (No. 1) having the above structure and comparative examples (No. 2 to 5)
The non-lubricated rotation test was conducted and the appearance was observed. The test results are shown in Table 1 below.

As is clear from the test results shown in Table 1, according to the numerical data, this example of No. 1 has small rotational torque and vibration acceleration, and the rotational torque is 2.2 kg · cm even at the high speed rotation of 1000 rpm. The vibration acceleration was 0.35 G, the smallest of the five combinations, and the increase in the bearing radial clearance was 25 μm, well below the largest No. 3, 83 μm. The appearance of the cage, ball, and inner and outer rings were all good, and satisfactory results were obtained.

On the other hand, if the cage, balls, and inner and outer rings are all made of metal that does not have self-lubricating properties, as in No. 5, the contact part will be damaged within a few hours after rotation and rotation will not be possible. It became clear that it was not suitable for use.

In addition, in No. 4, favorable results were obtained next to the present example in terms of numerical data and appearance condition, but it is considered that this is because the combination was the same as that of the present example except nylon of the cage.

Further, FIG. 4 shows the amount of dust generated for each particle size with respect to the test time, using the hardness of the carbon sphere as a parameter. The data and test conditions are as follows.

Material A Inner ring: Material SUS440C Hardness 660Hv Outer ring: Material SUS440C Hardness 660Hv Sphere: Carbon hardness 615Hv Retainer: Fluorine resin Material B Inner ring: Material SUS440C Hardness 660Hv Outer ring: Material SUS440C Hardness 660Hv Ball: Carbon hardness 990Hv Resin Inner ring: Material SUS440C Hardness 660Hv Outer ring: Material SUS440C Hardness 660Hv Ball: Carbon Hardness 1700Hv Cage: Fluorine resin Test conditions Rotation speed 100rpm Load 0.3kgf Temperature Normal temperature Air volume 8 × 10 ^-3 m ₃ / s As is clear from this FIG. In addition, when the hardness of the carbon ball becomes 1.5 times the hardness of stainless steel (SUS440C) (data
(Corresponding to B and Material C), the amount of dust generated from the carbon sphere is extremely small. Therefore, the transfer of the fluororesin from the fluororesin cage to the balls and the inner and outer rings proceeds smoothly, and the abrasion powder of the carbon balls, which is generated in an extremely small amount, is incorporated in the transfer film of the fluororesin, The discharge in the rolling bearing is prevented and the surrounding environment is not polluted. It has been found that when the hardness of the carbon balls is 1.5 times or more the hardness of the inner and outer races, the usage conditions of the clean room and the like are satisfied and the durability conditions actually required are satisfied. It was found that when the hardness of the carbon sphere was 1.5 times or less that of the inner and outer rings, this condition was not satisfied.

Based on the above experimental results, the cage is made of fluororesin, the balls are made of carbon, the inner and outer rings are made of bearing steel or stainless steel, and the hardness of the carbon balls is 1.5 times the hardness of the inner and outer rings made of bearing steel or stainless steel. It has been found that this makes it possible to prevent wear of the carbon balls during rolling and to withstand a high load.

The present invention can be applied not only to ball bearings but also to roller bearings, and, of course, to radial bearings and thrust bearings. In addition to the crown-shaped cage, a machined cage may be used.

<Effects of the Invention> As is clear from the above, the rolling bearing of the present invention is formed of a bearing ring made of bearing steel or stainless steel, a rolling element made of carbon, and a fluororesin holding the rolling element. Since it is equipped with a cage, the carbon of the rolling elements performs a lubricating action in the initial stage of rotation, while as the rotation progresses, the fluororesin of the cage transfers to the rolling elements and subsequently to the bearing ring, which causes the lubricating action. When done well, the wear resistance is greatly improved.

Further, since the hardness of the rolling element is set to be 1.5 times or more as high as that of the bearing ring, it is possible to prevent abrasion of the rolling element and withstand a high load, and to reduce the amount of dust generation.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention, FIGS. 2 (a) and 2 (b) are schematic cross-sectional views of a cage of each embodiment, FIG. 3 is a cross-sectional view of a conventional example, and FIG. 4 is carbon. Materials A, B, C with different hardness of ball making
It is a figure showing the amount of dust generation for every particle size. 1,11 …… Inner ring, 2,12 …… Outer ring, 3,13 ……
Sphere, 5,14 ... Cage, 15 ... Opening.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-45103 (JP, A) Actual opening S50-141038 (JP, U) Actual opening S57-56218 (JP, U) Actual opening S34- 20913 (JP, Y1)

Claims (1)

[Scope of utility model registration request] 1. A raceway ring made of bearing steel or stainless steel, a rolling element made of carbon, and a cage made of fluororesin for holding the rolling element, the hardness of the rolling element being the raceway. A rolling bearing characterized in that the hardness of the ring is 1.5 times or more.