JP2540977Y2 - Rolling bearing - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease lubricated bearing, and more particularly to a rolling bearing suitable for a high-temperature rotating part having a low temperature rise, such as a main shaft bearing of a machine tool.

[0002]

2. Description of the Related Art In grease lubrication, grease is generally used by sealing grease in the interior of a bearing, that is, in the gaps between components such as rolling elements, inner and outer rings, and cages.

In this case, if the amount of grease held between the components is small, the lubrication life of the bearing is shortened. Although it is possible to increase the amount of grease to be filled to some extent, if a large amount of grease is filled between the above-mentioned parts, heat generation due to the stirring resistance of the grease will increase in the initial stage of operation, and excess grease will be discharged and familiarized. There is a problem that the time required for the break-in operation to improve the condition becomes long.
In addition, the amount of grease retained is reduced due to the centrifugal force during rotation, and it is difficult to improve the grease life.
In particular, when the bearing is used for a machine tool, heat generated in the bearing affects the processing accuracy. Therefore, it is necessary to reduce the generated heat as much as possible.

As a solution to such a problem,
The present applicant has proposed a method in which a lubricant such as grease is sealed in a reservoir provided in the inner ring spacer to extend the lubrication life of the bearing (Japanese Utility Model Application No. 3-49662, Japanese Utility Model Application No. Hei 3-7760).
No. 9). In these proposals, a small gap generated by unevenness of the surface roughness of the mating surface and a minute slit formed in the mating surface are used as the lubricant outflow passage, and the lubricant flows from the pool to the vicinity of the rolling surface. Is carried out by utilizing a capillary phenomenon due to a minute gap or a minute slit in the lubricant outflow path, or a centrifugal force due to rotation. For this reason, the effect of restricting the outflow amount was large, and a very small amount of lubricant could be supplied even during high-speed rotation. The outflow amount is adjusted by the surface roughness, the size and the number of the minute slits, and the like.

[0005]

However, on the other hand, there is a concern that the supply of the lubricant may be insufficient at a high temperature because the drawing effect is too large. As in recent years, in a situation where the number of rotations used in grease lubrication becomes higher and higher, there is a possibility that seizure may occur even if the bearing temperature rises or slight lubrication is insufficient. A sign of bearing seizure is an abnormal rise in temperature of the bearing. Therefore, means for increasing the amount of lubricating oil in response to the rise in bearing temperature is desired.

An object of the present invention is to provide a rolling bearing that can supply a small amount of lubricant filled in a pool portion with operation, thereby improving lubrication life and reliably preventing seizure. .

[0007]

According to the rolling bearing of the present invention, an inner race spacer provided with a lubricant storage space inside is formed by an inner peripheral part and an outer peripheral part which are fitted into and out of each other. It is made of a material having a larger coefficient of linear expansion than inner peripheral parts. The fitting surface between the inner peripheral part and the outer peripheral part is a part of a lubricant outflow passage that opens from the lubricant reservoir space to the vicinity of the rolling path of the rolling element.

[0008]

According to this structure, the lubricant or its component in the lubricant reservoir space passes through the fitting surface between the inner peripheral part and the outer peripheral part of the inner race spacer, and is accompanied by the capillary phenomenon and rotation of the inner race spacer. It is supplied near the rolling elements by centrifugal force. Therefore, replenishment is performed little by little over a long period of time.

When the lubrication is insufficient, the bearing temperature rises. However, since the linear expansion coefficient of the outer part of the inner race spacer is larger than that of the inner part, the clearance of the fitting surface becomes larger as the temperature rises. Become. Therefore, the supply amount of the lubricant increases, and the lack of lubrication is eliminated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. This embodiment is an example applied to an inner ring rotating double row angular contact ball bearing.

In this double row bearing, the inner rings 2 of the bearings 1 and 1 in each row are individually provided and the outer ring 3 is shared, and an inner ring spacer 4 is provided between the inner rings 2 and 2. The rolling element 5 is spherical, and is held in a pocket of the retainer 6. Inner ring 2
Is fixed to a rotating shaft (not shown), and the outer race 3 is fixed to a housing which is a stationary member.

The inner ring spacer 4 is composed of two parts, an inner part 4a and an outer part 4b fitted inside and outside.
A lubricant reservoir space 7 is formed between the circumferential groove provided on the outer diameter surface of the first member and the outer peripheral part 4b. A through-hole 8 for preventing negative pressure, which penetrates the lubricant reservoir space 7,
Is provided. The holes 8 need not always be provided.

The inner peripheral part 4a and the outer peripheral part 4b are tightly fitted to each other, but a small gap is formed on the fitting surface 9 due to unevenness due to the surface roughness of the finished work (for example, 0.2 to 10 μm). Is done. The outer peripheral part 4b is made of a material having a larger linear expansion coefficient than the inner peripheral part 4a.

As shown in FIG. 2, a slit 10 having a small width d is provided entirely or partially between the inner race 2 and the side end surface of the outer peripheral part 4b of the inner race spacer 4. The slit 10 and the fitting surface 9 form a lubricant outflow path 11 that opens from the lubricant storage space 7 to the rolling path 12 of the rolling element 5.

At the time of assembling the bearing, the rolling path 12 is filled with a lubricant. However, the amount of the lubricant is generally smaller than that of the rolling path, and the lubricant is filled in the lubricant reservoir space 7 as much as possible.
As the lubricant to be filled in the lubricant reservoir space 7, in addition to general semi-solid or solid grease, liquid grease, plastic grease, oil-impregnated resin, woven cloth or felt containing lubricating oil, or the like is used. can do. Plastic
Cook grease is made of ultra-high molecular weight polyethylene or low molecular weight
Heat the mixture of grease with resin such as polyethylene.
It is a composition that is melted and solidified by cooling.
Something that seeps into is being developed.

According to this configuration, the lubricant or its component sealed in the lubricant reservoir space 7 oozes out from the fitting surfaces 9 of the inner and outer parts 4a and 4b of the inner race spacer 4 in both axial directions by capillary action. . The lubricant or its component that has oozed out to the side end surface of the inner race spacer 4 flows in the outer diameter direction due to the centrifugal force accompanying the rotation of the inner race spacer 4, and is supplied to the raceway surface of the rolling path 12. When the lubricant is a semi-solid grease, the grease base oil mainly separates from the thickener and flows out.

This bearing is provided with the lubricant reservoir space 7 as described above.
The lubrication life is improved because the lubricant or its components enclosed therein are replenished little by little. Also, rolling path 1
2, a small amount of lubricant can be lubricated between parts such as rolling elements and cages, so that a small amount of lubrication can be achieved. Therefore, heat generation due to agitation resistance is reduced, and the time required for running-in to improve familiarity is reduced. .

When the amount of lubricating oil in the rolling path 12 is insufficient, the bearing temperature rises even if the amount is insufficient, but the linear expansion coefficient of the outer part 4b of the inner race spacer 4 is larger than that of the inner part 4a. Therefore, the interference of the fitting surface 9 decreases as the temperature rises. Therefore, the supply amount of the lubricant increases, and the lack of lubrication is eliminated. Therefore, seizure due to insufficient lubrication is prevented. Due to these effects, this bearing is suitable for a portion that rotates at high temperature and rotates at high speed, such as a bearing for a main shaft of a machine tool.

FIGS. 3 and 4 show another embodiment. In this example, a small groove 9a is formed on the fitting surface 9. The minute grooves 9a may be provided in either the inner peripheral part 4a or the outer peripheral part 4b, but in this embodiment, they are provided in the inner peripheral part 4a as shown by oblique lines in FIG. The minute grooves 9a are provided in the axial direction over the entire length of the thick portion of the inner peripheral part 4a, and are provided at a plurality of positions in the circumferential direction. The depth of the minute groove 9a is
The depth is such that when the rotation is stopped, the lubricant is held without flowing out due to its own surface tension.
It is preferably 1 mm or less. For example, it is formed with a groove depth of about 0.03 to 0.05 mm. The groove width is formed, for example, to about 0.2 mm. The processing of the minute grooves 9a is performed by etching or rolling. Other configurations are the same as those in the above embodiment.

When the minute groove 9a is formed in the fitting surface 9 as described above, the lubricant or its component is minutely formed due to the capillary phenomenon as compared with the case where the gap formed by the surface roughness of the fitting surface is used as the flow path. The entire groove 9a is easily filled. Therefore, even when the rotation speed is low, the bleeding of the lubricant becomes easy, and the lubrication life when using at low speed rotation is improved. Also in the case of this embodiment, since the linear expansion coefficient of the outer peripheral part 4b of the inner race spacer 4 is larger than that of the inner peripheral part 4a, the supply amount is increased due to the temperature rise when insufficient lubrication occurs. A good image sticking prevention effect is obtained.

In each of the above embodiments, the lubricant storage space 7 is formed in an annular shape, but the lubricant storage space 7 may be divided into a plurality of portions in the circumferential direction. In addition, the present invention is applicable not only to double-row angular contact ball bearings but also to single-row angular contact ball bearings and other rolling bearings in general.

[0022]

The rolling bearing according to the present invention is provided with an inner race spacer having a lubricant reservoir space therein, and the inner race spacer is composed of an inner peripheral part and an outer peripheral part which are fitted to each other, and a fitting surface thereof. Is used as the lubricant outflow passage, so that the lubricant or its component sealed in the lubricant reservoir space is naturally replenished to the vicinity of the rolling element by a capillary phenomenon or centrifugal force caused by rotation of the inner ring spacer. Therefore, the lubricant is replenished little by little over a long period of time,
Excellent lubrication durability is obtained. In addition, since the outer part is made of a material having a larger linear expansion coefficient than the inner part, when the bearing temperature rises due to insufficient lubrication or the like, the gap between the fitting surfaces serving as the lubricant outflow path increases. The supply amount increases and seizure can be reliably prevented.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of one embodiment of the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a partial cross-sectional view of another embodiment of the present invention.

FIG. 4 is a perspective view of an inner peripheral part of the inner race spacer.

[Explanation of symbols]

2 ... inner ring, 3 ... outer ring, 4 ... inner ring spacer, 4a ... inner peripheral parts,
4b: peripheral parts, 5: rolling element, 6: retainer, 7: lubricant storage space, 9: fitting surface, 10: slit, 11: lubricant outflow path

Claims (1)

(57) [Scope of request for utility model registration] An inner ring spacer formed of an inner peripheral part and an outer peripheral part which fits inside and outside each other and has a lubricant reservoir space between both parts is provided, and an inner ring spacer is provided between the inner peripheral part and the outer peripheral part through a fitting surface of the inner peripheral part and the outer peripheral part. A small lubricant outflow passage extending from the lubricant storage space to the vicinity of the rolling path of the rolling element, wherein the outer peripheral component is made of a material having a larger linear expansion coefficient than the inner peripheral component.