JP2001099165A - Bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bearing device capable of corresponding to high speed rotation though grease lubrication is used. SOLUTION: Grease pressed out by rotation of a ball 5 at operating time is recovered by a grease reservoir 7, and the recovered grease is transmitted in external peripheral surfaces 3a, 3a' of inner ring bushes 3, 3' by utilizing centrifugal force, and is supplied to the ball 5 to be used for lubrication, so that stable lubrication can be performed over a long period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing device for rotatably supporting, for example, a main shaft of a machine tool rotating at high speed.

[0002]

2. Description of the Related Art Lubrication of bearings mainly includes grease lubrication and oil lubrication. Grease lubrication uses the grease sealed in the bearing to perform lubrication.In general, compared to oil lubrication in which lubrication is performed using lubricating oil supplied from the outside, the structure around the bearing to be lubricated is generally reduced. Although it is excellent in that it can be simplified and that foreign matter from the outside of the bearing can be suppressed, there is a problem that it is difficult to cool the inside of the bearing and to cope with high-speed rotation.

Generally, when a main shaft of a machine tool or the like is rotatably supported by a rolling bearing, it is common to use grease lubrication which can provide a compact configuration without providing an oil supply device or the like. Such rolling bearings are often lubricated with grease excellent in high speed and low heat generation, such as grease such as Isoflex NBU15 manufactured by Cruiba.

[0004]

By the way, in order to improve the processing efficiency and the productivity, the machine tool is required to have a higher speed, and the rotational speed of the spindle tends to be higher. However, Dmn 800,000 (rpm · mm)
The above-mentioned grease lubrication is not enough to properly lubricate a bearing corresponding to a high-speed rotation exceeding the above range.

More specifically, when grease lubrication is used to lubricate a high-speed rotating bearing, there is a problem that the life of the lubricant can be extended relatively early unless the lubricant is replenished in a short cycle. is there. In particular, in the case of a bearing for a main shaft, in order to suppress heat generation, the amount of grease sealed in the bearing is often reduced to 1/2 or less of the usual amount. In a normal bearing, grease is applied to the inner space of the bearing for 30 minutes.
Up to 40%, but generally 10 to 10
Since it is 15%, the lubrication life is shortened accordingly. In particular, in the case of a main shaft rotating at a high speed, the temperature increases due to the increased heat generated by the bearing, and there is a problem that grease deterioration is promoted.

Further, at high speeds, there is a problem that grease deterioration is accelerated even by a small amount of foreign matter. Due to such a problem, the life of the grease may be reached very early, and the bearing may be damaged if used as it is. In order to prevent such a problem, it is conceivable to supply grease before the end of the service life.However, it is necessary to perform the operation in a short cycle, and it is easy for foreign substances to be caught in the lubrication. Replenishment is also difficult.

[0007] On the other hand, there is an idea to lubricate rolling bearings that support the main shaft of a machine tool by using oil lubrication that can cope with high-speed rotation such as oil mist lubrication, oil air lubrication, and oil jet lubrication that are already in practical use. is there. However, each of these oil lubrications requires a lubricant supply device and also requires a treatment for draining oil, which causes another problem that the lubrication system becomes large.

The present invention has been made in view of the above problems, and has as its object to provide a bearing device that can cope with high-speed rotation while using grease lubrication.

[0009]

In order to achieve the above object, a bearing device according to the present invention comprises an inner ring, an outer ring, a rolling element rotatably disposed between the inner ring and the outer ring, and A fixed amount of lubricant is stored in advance, and a storage unit configured to collect the lubricant extruded to the side of the rolling element, and the lubricant stored in the storage unit is centrifugally applied. And a supply unit that supplies the rolling element, wherein the storage unit includes a circumferential groove formed on a side surface of an outer ring member that is arranged close to the outer ring, and the supply unit includes the supply unit, Formed on an inner ring member arranged close to the inner ring,
And an inclined surface inclined radially outward as approaching the inner ring.

[0010]

According to the bearing device of the present invention, an inner ring, an outer ring, a rolling element rotatably disposed between the inner ring and the outer ring, and a predetermined amount of lubricant are stored in advance. A storage unit configured to collect the lubricant pushed to the side of the rolling element, and a supply unit configured to supply the lubricant stored in the storage unit to the rolling element using centrifugal force. Wherein the storage section includes a peripheral groove formed on a side surface of an outer ring member arranged close to the outer ring, and the supply section includes an inner ring member arranged close to the inner ring. The lubricant pushed out by the rotation of the rolling element at the time of operation is collected by the storage portion, since the upper surface is formed on the upper portion and includes an inclined surface inclined toward the radially outer side as approaching the inner ring. And the lubricant recovered by the storage unit is centrifuged. Wherein is supplied to the rolling elements by the supplying unit by using the order employed in the lubricating, it is possible to perform stable lubrication over a long period of time.

Further, a predetermined gap is formed between the outer ring member and the inner ring member included in the outer ring member, and respective surfaces of the outer ring member and the inner ring member opposed to each other with the gap interposed therebetween. As long as it includes an inclined surface inclined outward in the radial direction as it approaches the inner ring, the lubricant that has reached such a gap can also be supplied to the bearing side using centrifugal force. Outflow to the outside can be effectively suppressed.

[0012] The amount of grease used as a lubricant in the bearing should be at least 50% of the internal space volume of the bearing.
That is, it is preferable to increase the amount of grease more than usual. Then, although the calorific value is increased by the rolling element agitating the grease, the heat is removed by external cooling corresponding to the agitation, and the problem is solved by setting the bearing temperature to a degree at which the progress of the grease deterioration is slow, that is, 70 to 100 ° C. .

At this time, it is desirable that both the shaft supported by the bearing and the housing in which the bearing is supported be cooled so as to remove heat from both the inner ring and the outer ring. Furthermore, grease is sealed from the time of assembly between the inner and outer rings, but grease pushed out of a bearing by rotation of the rolling element is
When stored in the storage unit, it is preferable that grease is sealed so as to substantially fill the space in the storage unit.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an axial sectional view of a bearing device according to a first embodiment of the present invention. In FIG. 1, the bearing device includes an angular contact ball bearing 10, ring-shaped outer ring bushes 2, 2 'as outer ring members, and ring-shaped inner ring bushes 3, 3' as inner ring members.

An angular contact ball bearing (hereinafter, referred to as a bearing) 10 often used to support a main shaft of a machine tool rotating at high speed includes an outer ring 1 attached to a housing (not shown) and a shaft (not shown). , A plurality of balls 5 which are rolling elements sandwiched between the outer ring 1 and the inner ring 4, and a retainer 6 for holding the balls 5.

The outer race bush 2 arranged so as to contact the left end surface of the outer race 1 of the bearing 10 has a circumferential groove 2a formed in the end surface on the bearing 10 side. Upper side wall surface 2 of peripheral groove 2a
c has a radial position substantially the same as that of the inner peripheral surface 1a of the outer race 1 of the bearing 10 at the contact portion. On the other hand, the lower side wall surface 2b of the peripheral groove 2a is located at substantially the same radial position as the outer peripheral surface 4a of the inner race 4, but is separated from the inner race 4. Lower side wall 2
The inner peripheral surface 2 d of the outer race bush 2, which corresponds to the back side of b, is a tapered inclined surface that is inclined radially outward toward the bearing 10 near the right end.

The inner race bush 3 is formed such that the inner peripheral surface 2d of the outer race bush 2 and the outer peripheral surface 3a of the inner race bush 3 are separated from each other by a small gap Δ (0.5 mm in this embodiment). The inner ring 2 is disposed so as to abut on the left end of the inner ring 4 inward in the radial direction. The outer peripheral surface (slope surface) 3a of the inner race bush 3 is tapered so as to be inclined outward in the radial direction toward the bearing 10, and the outer peripheral surface 4a of the inner race 4 and the outer peripheral surface of the inner race bush 3 at the contact portion. 3a has substantially the same radial position.

The outer race bush 2 'arranged so as to contact the right end surface of the outer race 1 of the bearing 10 has a circumferential groove 2a' formed in the end surface on the bearing 10 side. The upper side wall surface 2c 'of the peripheral groove 2a' is substantially the same in radial position as the inner peripheral surface 1a of the outer race 1 of the bearing 10 at the contact portion. On the other hand, the circumferential groove 2
The lower side wall surface 2 b ′ of a ′ is located at substantially the same radial position as the outer peripheral surface 4 a of the inner race 4, but is separated from the inner race 4.
The inner peripheral surface 2d 'of the outer race bush 2', which is on the back side of the lower side wall surface 2b ', is a tapered inclined surface which is inclined radially outward toward the bearing 10 near the left end thereof.

The inner race bush 3 'is separated from the inner race 2d' of the outer race bush 2 'by a small gap Δ (0.5 mm in the present embodiment) from the outer race 3a' of the inner race bush 3 '. Is disposed so as to abut the right end of the inner ring 4 inside the outer ring bush 2 ′ in the radial direction.
The outer peripheral surface (inclined surface) 3a 'of the inner race bush 3' is
As it goes toward 0, the outer peripheral surface 4b of the inner race 4 and the outer peripheral surface 3a 'of the inner race bush 3' have substantially the same radial position at the contact portion. I have.

Each of the outer race bushes 2 and 2 'and each of the inner race bushes 3 and 3' have basically the same structure, but in this embodiment, the bearing 10 is of an angular contact type. In view of this, it has slightly different dimensions according to its asymmetric shape.
The space 8 in the bearing 10 and the space (grease reservoir) 7 in the circumferential grooves 2a and 2a 'are filled with grease. The grease filling amount of the space 8 is 40 to 100% of the space volume.
(Preferably 50-100%). The space volume is a space volume excluding the volume of the ball 5 and the retainer 6 from the space 8 formed between the inner peripheral surface 1a of the outer ring 1 and the outer peripheral surface 4a of the inner ring 4.

Next, the operation of this embodiment will be described. When the inner ring 4 rotates together with a shaft (not shown), the ball 5 moves in the circumferential direction together with the retainer 6 while rolling between the outer ring 1 and the inner ring 4. The grease filled in the space 8 is pushed out to the side of the bearing 10, and the outer ring 1 is centrifuged by the centrifugal force.
The grease moves along the inner peripheral surface 1a of the grease and moves to the grease reservoir 7, but a part of the filled grease remains in the space 8.

On the other hand, since the grease reservoir 7 serving as a storage portion is initially filled with the amount of grease that is filled in the entire reservoir space when the extruded grease is added, the grease reservoir 7 is filled with grease. Grease is
It is in a state where it is easy to move outward with a small force.
Here, the grease that has moved outward from the grease reservoir 7 is applied to the outer peripheral surface 3 of the inner race bushes 3, 3 'as a supply unit.
a, 3a ', but since the inner race bushes 3, 3' rotate at a high speed, the grease, particularly the oil contained in the grease, propagates on the inclined surface based on the centrifugal force to cause the inner race 4 of the bearing 10 to rotate. It is supplied to the outer peripheral surface 4a, so that the raceway surface of the ball 5 can be lubricated.

The outer race bushes 2, which rotate relative to each other,
Although a slight gap Δ is formed between 2 ′ and the inner ring bushes 3 and 3 ′, since such a gap is small,
When the grease moved outward from the grease reservoir 7 reaches the clearance Δ, it adheres to the inner peripheral surfaces 2d, 2d ′ of the outer ring bushes 2, 2 ′, or the outer peripheral surfaces 3a, 3a of the inner ring bushes 3, 3 ′. 'Will adhere to.

Here, the inner peripheral surface 2 of the outer race bush 2, 2 '
d, 2d 'and the outer peripheral surfaces 3a, 3
Since a ′ is a tapered inclined surface, the inner ring bush 3.3 ′ rotates at a high speed. Therefore, the grease is transmitted along the inclined surface based on the centrifugal force and the outer peripheral surface of the inner ring 4 of the bearing 10. 4a. Thereby,
Leakage of grease to the outside through the gap Δ can be suppressed as much as possible. When the bearing is stationary, no centrifugal force is generated, but grease hardness increases due to a decrease in the temperature of the bearing, thereby suppressing grease leakage.

As described above, by circulating and using the grease, particularly the oil contained in the grease, a long lubrication life can be realized. The problem of heat generation due to abundant lubrication is a problem that can be counteracted by cooling the housing or the shaft vigorously.

Another advantage of this embodiment is that foreign matter is prevented from entering the grease from the outside. That is, first, clean space is filled with the clean grease into the space 8 and the grease reservoir 7, and after the bearing 10 is combined with the outer ring bushes 2, 2 'and the inner ring bushes 3, 3', the outer ring bushes 2, 2 Unless the outer ring 1 is separated from the outer ring 1, the inner ring bushes 3, 3 'do not move in the axial direction from the inner ring 3, so that the grease space is sealed and foreign matter intrusion from the outside is suppressed.

FIG. 2 is a diagram showing a modification of the present embodiment.
FIG. In the modification of FIG. 2, the bearing device shown in FIG. 1 is arranged back to back. The angular contact bearing 10 is generally used under a light preload. For example, if the axial length of the inner race bush 3 is slightly shorter than the axial length of the outer race bush 2, by applying a preload in the direction of the arrow, the bearing 1
The play within 0 can be eliminated.

FIG. 3 is a sectional view similar to FIG. 1 showing a second embodiment. The second embodiment differs from the first embodiment in the axial length of the inner race and the inner race bush. That is, the inner ring bushings 13 and 13 'are elongated by the length of the inner ring 14 of the bearing 20 being shortened. In other respects, the configuration is the same as that of FIG.

According to the present embodiment, the inner race bush 1
Since the outer peripheral surfaces 13a and 13a 'of the third and 13' are extended and reach below the retainer 6, a part of the grease which has moved on the outer peripheral surfaces 13a and 13a 'by centrifugal force further increases. Due to the centrifugal force, the ball 6 jumps on the cage 6 and travels along the cage 6 to reach the ball 5. That is, similarly to the above-described embodiment, grease lubrication can be performed through the outer peripheral surface of the inner ring 14 and grease lubrication can be performed through the retainer 6, so that lubrication efficiency can be further improved.

Although the present invention has been described with reference to the embodiments, the present invention should not be construed as being limited to the above-described embodiments, and it is needless to say that modifications and improvements can be made as appropriate. is there. For example, in the present embodiment, an angular contact ball bearing has been described as an example.
It is also applicable to cylindrical roller bearings and other types of bearings. Further, the outer race bush and the inner race bush can be formed in a body structure with the outer race and the inner race, and in this case, cleanliness management and grease circulation become more effective.

[0031]

According to the bearing device of the present invention, the inner ring, the outer ring, the rolling element rotatably disposed between the inner ring and the outer ring, and a predetermined amount of lubricant are stored in advance. A storage unit configured to collect the lubricant extruded to the side of the rolling element, and a lubricant stored in the storage unit supplied to the rolling element using centrifugal force. A supply section, wherein the storage section includes a peripheral groove formed on a side surface of an outer ring member arranged close to the outer ring, and the supply section is arranged close to the inner ring. Since it includes an inclined surface formed on the inner race member and inclined radially outward as approaching the inner race, the lubricant pushed out by the rotation of the rolling element during operation is collected by the storage section. And the lubricant recovered by the storage unit is Since supplied to the rolling elements by the supplying portion by utilizing the centrifugal force employed in the lubricating, it is possible to perform stable lubrication over a long period of time. Therefore, according to the present invention, a complicated lubrication device is unnecessary,
A high-speed rotating and long-life bearing can be realized, and a highly reliable machine tool spindle and the like can be realized.

[Brief description of the drawings]

FIG. 1 is an axial sectional view of a bearing device according to a first embodiment of the present invention.

FIG. 2 is a view similar to FIG. 1, showing a modification of the present embodiment.

FIG. 3 is a sectional view similar to FIG. 1, showing a second embodiment.

[Explanation of symbols]

 Reference Signs List 1 outer ring 2, 2 'outer ring bush 3, 3', 13, 13 'inner ring bush 4, 14 inner ring 7 grease reservoir 10, 20 angular contact ball bearing

Claims (2)

[Claims] 1. An inner ring, an outer ring, a rolling element rotatably disposed between the inner ring and the outer ring, and a predetermined amount of lubricant stored in advance, and a side of the rolling element A storage unit configured to collect the extruded lubricant, and the lubricant stored in the storage unit, using centrifugal force,
A supply unit that supplies the rolling element; the storage unit includes a peripheral groove formed on a side surface of an outer ring member that is arranged close to the outer ring; and the supply unit is close to the inner ring. A bearing device formed on an inner race member arranged in a manner arranged in a radially outward manner as approaching the inner race. 2. A predetermined gap is formed between the outer ring member and the inner ring member included in the outer ring member, and respective surfaces of the outer ring member and the inner ring member opposing each other with the gap interposed therebetween. The bearing device according to claim 1, wherein the bearing device includes an inclined surface that is inclined radially outward as approaching the inner ring.