JP2002122149A - Angular ball bearing, and machine tool using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To consistently feed lubricating oil to a rolling part in grease lubrication even in any attitude, to stabilize the strength of a holder during the rotation at high speed, and to reduce the temperature rise. SOLUTION: Grease storage grooves 6 and 6 connected to a raceway groove 2a are formed in an inner circumferential surface of an outer ring 2 on both sides of the raceway groove 2a. The grease storage groove 6 is provided so as to ensure a contact surface of the raceway groove 2a of the outer ring 2 with the ball 3. When the holder 4 is of outer ring guide type, a holder guide surface 8 of the outer ring 2 is provided on both sides of the raceway groove 2a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular contact ball bearing used for, for example, a main shaft of a machine tool rotating at high speed or a winder of a textile machine, particularly an angular contact ball bearing suitable for grease lubrication, and a machine using the same. About the machine.

[0002]

2. Description of the Related Art In an angular contact ball bearing used for a main shaft of a machine tool, as shown in FIG.
On one side of 2a, a tapered counter bore 55 is formed. The counter bore 55 has a function of discharging the lubricating oil inside the bearing. To suppress the temperature rise,
When oil lubrication such as air oil lubrication, which requires the lubricating oil to be discharged to the outside of the bearing, is used, the counter bore 5
5 works advantageously. However, the outer bore 52 of the outer bore 55
Means that the lubricating oil retains poorly in the case of grease lubrication,
There has been a problem that poor lubrication occurs and the durability of the bearing is disadvantageous. In order to solve this, an angular ball bearing in which a grease storage groove 56 connected to the raceway groove 52a is formed in the outer ring 52 as shown in FIG. 9 has been developed (Japanese Patent Laid-Open No. 11-108068). The grease storage groove 56 is provided such that a contact surface between the raceway groove 52a and the ball 53 is obtained.

[0003]

However, since the grease storage groove 56 is provided on only one side, when the grease storage groove 56 is used for supporting the vertical main shaft 70 as shown in FIG. Is located below the raceway groove 52a in the direction of gravity. In the example shown in the figure, the grease storage groove 56 in the lower bearing 60 is lower than the raceway groove 52a. As described above, when the grease storage groove 56 is disposed on the lower side, the grease accumulated in the grease storage groove 56 easily stays at a position away from the raceway groove 52a due to heat, gravity, and vibration, and is sufficiently lubricated. May not be able to contribute. In addition, FIG. 9 shows that grease lubrication is important for improving the durability of the bearing in grease lubrication, and that the provision of the grease storage groove 56 near the raceway groove 52a is effective. However, when the grease storage groove 56 is provided, the following problem occurs when the retainer 54 is an outer ring guide. That is, the behavior of the retainer 54 is restricted by the inner peripheral surface of the outer ring 52. In the case of the outer ring guide retainer 54, when the grease storage groove 56 is provided, the retainer guide surface of the outer ring 52 decreases, and at the time of high-speed rotation. There is a problem that the behavior of the retainer 54 is not stable.

An object of the present invention is to provide an angular ball bearing capable of stably supplying lubricating oil to a rolling portion in grease lubrication even in various postures and arrangements. Another object of the present invention is to stabilize the behavior of the cage during high-speed rotation and reduce the temperature rise.
Still another object of the present invention is to provide a machine tool capable of performing stable grease lubrication for a bearing supporting a main shaft. Still another object of the present invention is to provide a machine tool capable of performing stable grease lubrication of a bearing even in a vertical spindle.

[0005]

An angular ball bearing according to the present invention is an angular ball bearing in which a ball held by a retainer is interposed between an inner ring and an outer ring. The grease storage groove connected to the raceway groove is formed on both sides of the raceway groove. The grease storage groove is such that a contact surface between the raceway groove of the outer ring and the ball is secured,
That is, the contact ellipse is provided so as not to be reduced by the grease storage groove. According to this configuration, the grease moves toward the outer ring due to the centrifugal force due to the high-speed rotation of the inner ring, and is stored in the grease storage groove via the raceway groove of the outer ring. Since the grease storage groove is connected to the raceway groove, the base oil is again supplied to the raceway groove from the grease stored in the grease storage groove, and is repeatedly used as lubricating oil. At this time, since the grease storage groove is formed on both sides of the raceway groove, lubrication characteristics are improved as compared with the case where the grease storage groove is formed only on one side. In particular, since there is a grease storage groove on both sides, any grease storage groove is located above the raceway groove in the direction of gravity regardless of the bearing combination and arrangement posture, such as when using a vertical shaft. Therefore, a stable supply of lubricating oil to the rolling portion is possible, and the durability is improved.

[0006] The retainer may be guided on an inner peripheral surface of an outer ring. In this case, it is preferable that guide surfaces of the outer race for guiding the cage are provided on both sides of the raceway groove. Thus, by providing the guide surfaces of the cage on both sides of the raceway groove and enabling the cage to be guided on both sides, the behavior of the cage is stabilized even during high-speed operation. Therefore, the temperature rise due to the behavior of the cage is reduced.

A machine tool according to the present invention has a main shaft supported by any one of the above-described angular ball bearings according to the present invention. Therefore, stable grease lubrication and durability of the bearing supporting the main shaft can be obtained. Further, when the bearing has a guide surface of a cage on both sides, improvement in machining accuracy of the machine tool can be expected due to a decrease in temperature rise of the main shaft bearing. In this machine tool, the spindle may be vertical. Even in the case of the vertical type as described above, any one of the grease storage grooves on both sides of the raceway groove is located above the raceway groove, and stable lubricating oil can be supplied to the rolling portion, and the durability is improved.

[0008]

Embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, this angular contact ball bearing 1
Numeral 0 indicates that the ball 3 is interposed between the inner ring 1 and the outer ring 2. The bearing 10 is used for grease lubrication. Ball 3
Are rotatably held by the retainer 4 at predetermined intervals in the circumferential direction. A raceway groove 1a and a raceway groove 2a are provided on the outer peripheral surface of the inner race 1 and the inner peripheral surface of the outer race 2 so that the contact angle with the ball 3 becomes a predetermined angle.

On the inner peripheral surface of the outer ring 2, grease storage grooves 6, 6 connected to the raceway groove 2a are formed on both sides of the raceway groove 2a. These grease storage grooves 6, 6 are provided so as to secure a contact surface between the raceway groove 2a and the ball 3, that is, to secure a contact ellipse. The grease storage groove 6 is formed continuously along the entire circumference of the inner peripheral surface of the outer ring, and formed so as to be connected to the raceway groove 2a over the entire circumference.

The retainer 4 is guided on the inner peripheral surface of the outer ring 2. The portion serving as the guide surface 8 on the inner peripheral surface of the outer ring 2 that guides the retainer 4 is provided on both sides of the raceway groove 2a.
The guide surfaces 8 are formed at portions along the grease storage grooves 6 on both sides. The guide surfaces 8 do not necessarily have to be provided on both sides. For example, as shown in FIG.
The guide surface 8 may be provided on only one of them. Thereby, the width of one grease storage groove 6 can be increased.

On the outer peripheral surface of the inner ring 1, a counter bore 7 having an outer diameter gradually decreasing outward is provided on one side of the raceway groove 1a, that is, on a side opposite to the direction in which the contact angle is generated. The inner peripheral surface of the outer race 2 has a cylindrical shape, and is not provided with a counter bore. At the time of assembling the bearing, the angular ball bearing 10 expands by heating the outer ring 2 to which the balls 3 are attached, and expands the inner ring 1 from the counter bore 7 side.
Can be assembled by inserting. Therefore, even if the outer ring 2 is not provided with a counter bore, there is no problem in assembling.

FIG. 3 shows a spindle device in a machine tool using the angular ball bearing of the embodiment shown in FIG. In the spindle device of this machine tool, a main shaft 11 is supported by a pair of angular ball bearings 10 and 10 and another rolling bearing 13. The pair of angular ball bearings 10, 10
The front part of the main shaft 11 is supported, and another rolling bearing 13 is
1 to support the rear. Double angular contact ball bearings 10,10
Are installed, for example, facing each other. As another rolling bearing 13, a cylindrical roller bearing or the like is used. This spindle device is of a built-in motor type and has a spindle 11
The rotor 15 of the motor 14 is provided on the outer periphery of the housing 12, and the stator 16 corresponding to the rotor 15 is provided on the inner periphery of the housing 12. The housing 12 has a bearing cooling jacket 17 and a motor cooling jacket 18. FIG. 3 shows a horizontal machine tool in which the main shaft 11 is oriented sideways, but the machine tool shown in FIG.
It may be a vertical type with 1a facing downward.

FIG. 4 shows a spindle bearing portion of a machine tool having a vertical spindle 11. The main shaft 11 is supported by a housing (not shown) via a plurality of angular ball bearings 10, 10 arranged vertically. These angular ball bearings 10 are the bearings shown in FIG. 1, and are arranged in a back-to-back combination. An inner ring spacer 19 and an outer ring spacer 20 are interposed between the inner rings 1 and 1 and between the outer rings 2 and 2 of the two angular ball bearings 10 and 10.

The angular ball bearing 10 according to the embodiment of FIG. 1 may be provided with seals 9 at both ends as shown in FIG. The seal 9 is a non-contact seal, and an outer peripheral portion is fitted into a seal mounting groove provided on an inner peripheral surface of the outer ring 2. FIG. 4 shows an example in which the angular contact ball bearing 10 is replaced with a seal in the machine tool shown in FIG.

The operation of the above configuration will be described. According to the angular contact ball bearing 10 shown in FIG. 1, the grease storage groove 6 connected to the raceway groove 2a is formed on the inner peripheral surface of the outer race 2 so that the contact surface between the raceway groove 2a of the outer race 2 and the ball 3 is secured. Track groove 2
Since it is formed on both sides of “a”, the lubricating property is improved as compared with the conventional grease storage groove formed on one side. Also,
Since the retainer guide surfaces 8, 8 are provided on both sides of the raceway groove 2a on the inner peripheral surface of the outer ring 2, the behavior of the retainer 4 during high-speed rotation is stabilized, and a rise in temperature due to the behavior of the retainer 4 is reduced. As shown in FIG. 4, when the pair of angular ball bearings 10, 10 are used on the vertical main shaft 11 so as to face rearward or frontward, both upper and lower angular ball bearings 1 are used.
At 0 and 10, any grease storage groove 8 is located above the raceway groove 6 in the direction of gravity. Therefore, a stable supply of lubricating oil to the rolling portion is possible, and the durability is improved.

As shown in FIG. 5, when seals 9 are provided on both end surfaces of the angular ball bearing 10, scattering of grease to the outside of the bearing can be suppressed, and durability can be further improved. . When a plurality of angular ball bearings 10 are used in an adjacent combination, even if the seal 9 on the mating surface side is omitted, the same effect as the case where the seals 9 are provided on both sides can be obtained.

Next, the results of each test will be described. First, the grease storage groove 6 on both sides in the embodiment of FIG. 1 was operated with an angular ball bearing (embodiment), and the conventional angular ball bearing having a grease storage groove 56 on only one side shown in FIG. 9 (conventional example). . The result is shown in FIG.
In this test, the temperature rise was almost the same at 10,000 rpm or less, but the temperature difference gradually started to increase from 10,000 rpm or more, and a temperature difference of about 3 ° C. was confirmed at 15000 rpm. The grease used was Isoflex NBU15 (manufactured by NOK Kluber).

FIG. 7 shows the endurance test results of each example when used on a vertical shaft. In this test, an example in which grease storage grooves 6 are provided on both sides shown in FIG. 1 (embodiment), an example in which grease storage grooves 6 are provided on both sides and seals 9 are provided on both sides shown in FIG. Tests were performed on an example having no grease storage groove shown in FIG. 8 (conventional example) and an example having a grease storage groove 56 on only one side shown in FIG. 9 (conventional example). The rotation speed was 12000 rpm, the contact surface pressure was 2.0 Gpa, and the grease used was a urea-based grease. As can be seen from the figure, in the conventional bearing without the grease storage groove (conventional example), at the time of 120 hours of operation, the surface of the raceway was damaged due to poor lubrication, whereas the one-sided grease storage groove ( In the conventional example), the service life could be extended up to 4.2 times, and with the grease storage grooves on both sides (embodiment) up to 7.6 times. In addition, with grease storage grooves on both sides,
In the example with the seals on both sides (embodiment), the service life could be extended to 2.2 times that of the case without the seal and to about 17 times that of the conventional product.

[0019]

According to the angular ball bearing of the present invention, the grease storage groove connected to the raceway groove is formed on the raceway groove so that a contact surface between the raceway groove of the outer race and the ball is secured on the inner peripheral surface of the outer race. Since it is formed on both sides, the lubrication characteristics of grease lubrication are improved, and even in various postures and arrangements, stable lubrication oil can be supplied to the rolling parts in grease lubrication,
The durability is improved. When the cage is guided by the inner peripheral surface of the outer ring, and when the guide surfaces of the outer ring for guiding the cage are provided on both sides of the raceway groove, the behavior of the cage during high-speed rotation is stable. However, the rise in temperature due to the behavior of the cage is reduced. Since the main shaft is supported by the angular contact ball bearing of the present invention, the machine tool of the present invention can perform stable grease lubrication of the main shaft supporting bearing and has excellent durability. Even when the main shaft is vertical, lubricating oil can be supplied to the rolling section from either grease storage groove on either side of the raceway groove,
Provides stable lubrication. In addition, when the guide surface of the outer ring that guides the retainer is provided on both sides of the raceway groove as the spindle support bearing, an improvement in machining accuracy of the machine tool is expected due to a decrease in temperature rise of the spindle bearing. be able to.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of an angular contact ball bearing according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of an angular contact ball bearing according to another embodiment of the present invention.

FIG. 3 is a partial cross-sectional view of a horizontal spindle type machine tool using the angular ball bearing according to the embodiment of FIG. 1;

FIG. 4 is a partial cross-sectional view of a vertical spindle type machine tool using the angular ball bearing according to the embodiment of FIG. 1;

FIG. 5 is a partial cross-sectional view of an example in which a bearing is provided with a seal in the vertical spindle type machine tool shown in FIG.

FIG. 6 is a graph showing the results of a temperature rise measurement test of the embodiment and a conventional example having a single-sided grease storage groove.

FIG. 7 is a graph showing endurance test results for each embodiment of the present invention and various conventional examples.

FIG. 8 is a partial cross-sectional view of a conventional example.

FIG. 9 is a partial sectional view of another conventional example.

FIG. 10 is a partial sectional view of an example in which the conventional example is used for a vertical spindle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inner ring 2 ... Outer ring 2a ... Raceway groove 3 ... Ball 4 ... Cage 6 ... Grease storage groove 8 ... Guide surface 9 ... Seal 10 ... Angular contact ball bearing 11 ... Spindle 12 ... Housing

Claims (5)

[Claims] In an angular ball bearing in which a ball held by a retainer is interposed between an inner ring and an outer ring, a contact surface between a raceway groove of the outer ring and the ball is secured on an inner peripheral surface of the outer ring. Thus, an angular ball bearing in which grease storage grooves connected to the raceway grooves are formed on both sides of the raceway grooves. 2. The angular ball bearing according to claim 1, wherein the cage is guided on an inner peripheral surface of an outer ring. 3. The angular ball bearing according to claim 1, wherein guide surfaces of an outer ring for guiding the cage are on both sides of the raceway groove. 4. A machine tool having a main shaft supported by the angular ball bearing according to claim 1. 5. The machine tool according to claim 4, wherein said spindle is a vertical type.