JP7152849B2 - rolling bearing - Google Patents

Description

TECHNICAL FIELD The present invention relates to rolling bearings, and more particularly to angular contact ball bearings capable of high-speed rotation applied to machine tool spindles, compressors, and the like.

Among rolling bearings, angular contact ball bearings can receive a composite load consisting of a radial load and a relatively large axial load. For this reason, they are often used in applications that require high-speed rotation under heavy loads, such as machine tools, medical equipment, construction machinery, and agricultural machinery, even in environments where the load direction varies.

As retainers for such angular contact ball bearings, there are known outer ring or inner ring guide type retainers and rolling element guide type retainers. Among them, for example, in an angular contact ball bearing provided with an outer ring guide type retainer, a clearance (a guide clearance) is provided between a guide portion of the retainer that contacts the outer ring and a contact surface of the outer ring. This guide clearance corresponds to the difference between the diameter of the inner peripheral surface of the outer ring and the diameter of the outer peripheral surface of the retainer. On the other hand, in the angular contact ball bearing, a clearance (pocket clearance) is also provided between the pocket formed by the retainer and the rolling elements.

For example, in the angular contact ball bearing disclosed in Patent Document 1, a cage made of resin is used, the size of the guide clearance is defined with respect to the guide diameter of the cage, and the size of the pocket clearance is determined by the size of the guide clearance. It stipulates that the In this way, by specifying the size of the guide gap, etc., it is possible to reduce whirling of the retainer during rotation of the bearing.

Japanese Unexamined Patent Application Publication No. 2001-12476

By the way, when the rolling bearing rotates, heat is generated due to sliding between the guide portion of the retainer and the contact surface of the bearing ring. Furthermore, when the bearing rotates at a high speed, the amount of heat generated increases. For example, even in the angular bearing of Patent Document 1, the amount of heat generated is considered to increase as the bearing slides. In this case, if the temperature of the cage and raceway ring rises due to an increase in the amount of heat generated, the cage may melt or the raceway ring may seize.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. The purpose is to provide bearings.

The rolling bearing of the present invention comprises an inner ring and an outer ring as bearing rings, a plurality of rolling elements arranged between the inner ring and the outer ring, and the plurality of rolling elements held at predetermined intervals in the circumferential direction. A rolling bearing in which the retainer is guided by the outer ring, the retainer including: an outer ring guide portion guided by the outer ring; and a notch portion formed to have a smaller diameter than the outer diameter of the portion.

The rolling bearing of the present invention comprises an inner ring and an outer ring as bearing rings, a plurality of rolling elements arranged between the inner ring and the outer ring, and the plurality of rolling elements held at predetermined intervals in the circumferential direction. A rolling bearing in which the retainer is guided by the inner ring, the retainer including an inner ring guide portion guided by the inner ring on an inner peripheral surface of the retainer, and the inner ring and a notch formed to have a larger diameter than the inner diameter of the guide.

The cutout portion is a recessed groove portion that is not open in the width surface of the retainer. Further, the retainer is a resin retainer made of synthetic resin. Further, the rolling bearing is an angular contact ball bearing that supports a main shaft of a machine tool.

The rolling bearing of the present invention comprises an inner ring and an outer ring as bearing rings, a plurality of rolling elements arranged between the inner ring and the outer ring, and the plurality of rolling elements held at predetermined intervals in the circumferential direction. The retainer is guided by the outer ring, and the retainer includes an outer ring guide portion guided by the outer ring and an outer diameter of the outer ring guide portion on the outer peripheral surface of the retainer. Therefore, the contact area between the outer peripheral surface of the retainer and the outer ring during rotation is smaller than when there is no notch. As a result, it is possible to suppress temperature rise due to sliding between the outer peripheral surface of the retainer and the outer ring, thereby preventing melting of the retainer and seizure of the outer ring. As a result, the rolling bearing can be used even under high-speed rotation, and is suitable as an angular contact ball bearing for supporting the spindle of a machine tool.

The rolling bearing of the present invention comprises an inner ring and an outer ring as bearing rings, a plurality of rolling elements arranged between the inner ring and the outer ring, and the plurality of rolling elements held at predetermined intervals in the circumferential direction. The cage is guided by the inner ring, and the cage includes an inner ring guide portion guided by the inner ring and an inner diameter of the inner ring guide portion on the inner peripheral surface of the cage. Since the cutout portion is formed to have a larger diameter than the cutout portion, the area of contact between the inner peripheral surface of the retainer and the inner ring during rotation becomes smaller than when there is no cutout portion. As a result, it is possible to suppress temperature rise due to sliding between the inner peripheral surface of the retainer and the inner ring, thereby preventing melting of the retainer and seizure of the inner ring. As a result, the rolling bearing can be used even under high-speed rotation, and is suitable as an angular contact ball bearing for supporting the spindle of a machine tool.

Since the notch portion is a concave groove portion, both sides of the groove portion can contact the bearing ring. Therefore, it is possible to suppress the temperature rise by reducing the contact area while suppressing whirling of the retainer during rotation of the bearing. Further, since the grooves do not open on the width surface of the retainer, lubricating oil or the like can be retained in the grooves, resulting in excellent lubricating properties.

Since the above retainer is a resin retainer made of synthetic resin, there is concern that mechanical strength may decrease due to temperature rise due to sliding. However, as described above, the rolling bearing of the present invention suppresses the temperature rise. Therefore, damage to the retainer can be prevented even during high-speed rotation.

1 is a partial cross-sectional view of an angular contact ball bearing according to an example of the present invention; FIG. FIG. 2 is a partial cross-sectional view of an angular contact ball bearing according to a conventional example; It is the cross-sectional schematic diagram which showed the other form of the notch part. FIG. 5 is a partial cross-sectional view of an angular contact ball bearing according to another example of the present invention; FIG. 4 is a diagram showing a spindle using the angular contact ball bearing of the present invention; It is a figure which shows the relationship between rotation speed and a temperature rise in an Example and a comparative example.

An embodiment of an angular contact ball bearing, which is a rolling bearing of the present invention, will be described with reference to FIG. FIG. 1 is a partial cross-sectional view of an angular contact ball bearing incorporating a resin retainer having a notch as the angular contact ball bearing of the present invention. As shown in FIG. 1, an angular contact ball bearing 1 includes an inner ring 2, an outer ring 3, balls 4, which are a plurality of rolling elements interposed between the inner ring 2 and the outer ring 3, and the balls 4 fixed in the circumferential direction. and a retainer 5 that holds them at intervals. The inner ring 2, the outer ring 3, and the ball 4 are in contact with each other at a predetermined angle θ (contact angle) with respect to the radial center line, so that a radial load and an axial load in one direction can be applied. . Lubricant such as grease is sealed around the balls 4 as needed.

In FIG. 1 , the retainer 5 has a pair of ring portions 6 and a plurality of pillars (not shown) connecting the pair of ring portions 6 . A pocket portion 7 is formed between the pair of ring portions 6 and adjacent pillar portions, and the ball 4 is stored in the pocket portion 7. - 特許庁The retainer 5 is of an outer ring guide type, and has an outer ring guide portion 5b that is guided by the outer ring 3 on a part of the outer peripheral surface 5a of the retainer. The angular contact ball bearing 1 is of a one-side outer ring guide type guided by the outer ring 3 on one side in the axial direction, and the outer ring guide portion 5b is provided on one side of the ball 4 in the axial direction. In this configuration, the retainer 5 is guided by the outer ring 3 by the outer ring guide portion 5 b coming into contact with the inner peripheral surface 3 a of the outer ring 3 .

A retainer 5 according to the angular contact ball bearing 1 of the present invention has a notch portion 5c on the outer peripheral surface 5a on the side of the outer ring guide portion 5b. The notch portion 5c is formed continuously from the outer ring guide portion 5b, and has a structure in which the outer ring guide portion 5b is notched toward the inner diameter direction. That is, the notch portion 5c is formed to have a smaller diameter than the outer diameter of the outer ring guide portion 5b. The notch portion 5c of the retainer 5 in FIG. 1 is formed from the outer ring guide portion 5b of one ring portion 6 to the width surface 5d. The notch 5c is open to the width surface 5d of the retainer. In addition, along the circumferential direction of the retainer 5, the cutout portion 5c may be formed continuously over the entire circumference, or may be formed intermittently. In addition, the retainer 5 of FIG. 1 is provided with a notch portion 5c only on the outer peripheral surface 5a on the side of the outer ring guide portion 5b (right side in the figure). A similar notch 5c may be provided.

Here, FIG. 2 shows a partial cross-sectional view of a conventional angular contact ball bearing. The angular contact ball bearing 11 of FIG. 2 includes an inner ring 12, an outer ring 13, balls 14, which are a plurality of rolling elements interposed between the inner ring 12 and the outer ring 13, and the balls 14 are held at regular intervals in the circumferential direction. A retainer 15 is provided. The retainer 15 associated with the angular contact ball bearing 11 in FIG. 2 is of a one-sided outer ring guide type, like the retainer 5 associated with the angular contact ball bearing 1 in FIG. Here, as shown in FIG. 2, the retainer 15 does not have a notch on the outer peripheral surface 15a on the side of the outer ring guide portion 15b. In other words, the outer peripheral surface 15a on the side of the outer ring guide portion 15b is formed so that there is no outer diameter difference. In contrast, the angular contact ball bearing (FIG. 1) according to the present invention has a configuration in which a part of the outer ring guide portion 15b of the angular contact ball bearing 11 is cut away. As a result, the contact area between the outer ring guide portion of the retainer and the inner peripheral surface of the outer ring during rotation is smaller than in the conventional configuration. As a result, it is possible to suppress the temperature rise due to the sliding of these members, and to prevent the cage from melting and the bearing ring from seizing.

The dimensions of the notch 5c can be changed as appropriate. For example, as shown in FIG. 1, as the dimensions of the notch 5c, the radial height is H and the axial length is L, and these can be changed as appropriate. For example, the radial height H may be about 0.1 to 1.0 mm, although it depends on the cage material and the diameter size of the cage. This is not preferable because it reduces the cross-sectional area and reduces the strength of the cage. In addition, since it is preferable to reduce the contact area with the inner peripheral surface (guide surface) of the outer ring by making the outer ring guide portion as small as possible, the axial length L = {(cage width) - pocket The diameter}/2 is the maximum, and it is preferable to reduce the diameter appropriately in consideration of the cage strength and heat generation.

The shape of the notch portion 5c is not particularly limited as long as it is formed to have a smaller diameter than the outer diameter of the outer ring guide portion 5b. Another form of the shape of the notch 5c is shown in FIG. FIG. 3 is a schematic cross-sectional view of the angular contact ball bearing 1 of the present invention with the balls 4 and cage 5 extracted. In FIG. 3A, a recessed groove is formed as the notch 5c. Both sides of the groove are formed by the outer ring guide portion 5b. In this configuration, the outer ring guide portions 5b on both sides of the groove contact the inner peripheral surface 3a of the outer ring 3 during rotation of the bearing, so whirling of the retainer 5 during rotation is suppressed. In addition, since the notch portion 5c serving as the groove portion does not open in the width surface of the retainer, lubricating oil or the like can be retained in the groove portion. Therefore, it is possible to prevent the lubricating oil from leaking out from the width surface even when the retainer rotates, so that the lubricating oil can be stably supplied to the guide portion.

In FIG. 3(b), the notch 5c forms an inclined surface inclined at a predetermined angle (angle of inclination α) from the outer ring guide portion 5b. The inclined surface connects the outer ring guide portion 5b and the width surface 5d. By forming the inclined surface, it is possible to reduce the amount of notched resin in the ring portion compared to the case of FIG. 1 while reducing the contact area of the guide portion to the same extent as in the case of FIG. As a result, it is possible to suppress a decrease in cage strength due to the formation of the notch. In addition, in FIG. 1 and FIG. 3, the notch portion is configured with a flat surface, but it may be configured with a curved surface.

Another embodiment of the angular contact ball bearing of the present invention will be described with reference to FIG. The retainer 5 associated with the angular contact ball bearing 1 shown in FIG. 4 is of an inner ring guide type that is guided by the inner ring 2 on one side in the axial direction. The retainer 5 has an inner ring guide portion 5f on its inner peripheral surface 5e. The inner ring guide portion 5f is provided on one side of the ball 4 in the axial direction. In this case, the inner ring guide portion 5f is guided by the inner ring 3 by coming into contact with the outer peripheral surface 2a of the inner ring 2 .

A retainer 5 according to the angular contact ball bearing 1 of FIG. 4 has a cutout portion 5g on an inner peripheral surface 5e on the inner ring guide portion 5f side. The notch portion 5g is formed continuously from the inner ring guide portion 5f, and has a structure in which the inner ring guide portion 5f is cut away from the inner ring guide portion 5f toward the outer diameter direction. That is, the cutout portion 5g is formed to have a larger diameter than the inner diameter of the inner ring guide portion 5f. 4 is formed from the inner ring guide portion 5f of one ring portion 6 to the width surface 5h. In addition, along the circumferential direction of the retainer 5, the notch 5c may be formed all around, or may be intermittently formed. Also, as in the case of the outer ring guide system shown in FIGS. 1 and 3, the size and shape of the notch 5g can be changed as appropriate.

The retainer 5 of the bearing of the present invention is preferably a resin retainer obtained by injection molding a resin composition. Injection molding is particularly preferable because the retainer guide portion can be formed with a mold. Examples of synthetic resins used in the resin composition include polyamide (PA) resin, polyphenylene sulfide (PPS) resin, polyetheretherketone (PEEK) resin, polyimide (PI) resin, and polyamideimide (PAI) resin. be done. Among these, it is preferable to use a PA resin because it has a high glass transition temperature and is excellent in rigidity, self-lubricating properties, and low friction properties. As a result, the amount of heat generated by the friction between the balls 4 and the cage 5 can be reduced even during high-speed rotation, and the temperature rise of the bearing ring can be suppressed. In addition, reinforcing fibers such as carbon fibers and glass fibers, and other additives may be added to the resin composition. Also, as the cage, a cage made by machining, such as a phenolic resin cage, may be used. In this case, the heat generation amount can be reduced by machining the retainer guide portion.

The angular contact ball bearing 1 of the present invention is particularly suitable for high-speed rotation because it can suppress heat generation due to sliding between the bearing ring and the retainer during rotation. It is preferably applied to a high-speed rotating device capable of rotating at 10,000 min ^-1 or more, more preferably at 20,000 min ^-1 or more. For example, it is applied to machine tool spindles and compressors.

FIG. 5 is a diagram showing a state in which the angular contact ball bearing 1 is attached to a machine tool main shaft (spindle). The spindle unit 21 has two angular ball bearings 1 . In FIG. 5, a main shaft 22 is supported by a back-mounted angular contact ball bearing 1 preloaded with a fixed position preload. The two angular ball bearings 1 are positioned by an inner ring spacer 23 and an outer ring spacer 24 interposed on the inner ring side and the outer ring side, respectively. A coolant passage 26 is provided in the outer cylinder 25 of the spindle unit 21 to prevent excessive temperature rise of the unit during operation. Other methods for lubricating the bearings in the machine tool spindle include, for example, grease lubrication, oil mist lubrication, air-oil lubrication, and jet lubrication, and any of them can be used.

Example An angular contact ball bearing (HSE014) with an inner diameter of 70 mm was used as the bearing. A cage made of PA resin obtained by injection molding was used for the cage of this bearing. The retainer is a one-side outer ring guide type retainer, and as shown in FIG. The dimensions of the notch are H=0.5 mm and L=1 mm.

Comparative Example An angular contact ball bearing similar to that of Example 1 was used, except that a one-sided outer ring guide type retainer having no notch on the outer peripheral surface of the retainer as shown in FIG. 2 was used.

A rotation test was performed using the angular contact ball bearings of the examples and the comparative examples. Each angular contact ball bearing was assembled with constant pressure preload to form a spindle unit. The main shaft was rotated from 20000 to 30000 min ^-1 by driving a motor installed on the main shaft via a speed increaser. The temperature of the outer ring was measured at each rotation speed within this range. The results are shown in FIG.

In FIG. 6, as the number of revolutions increases, the difference in the temperature rise of the outer ring between the example and the comparative example increases. For example, at a rotational speed of 30000 min ⁻¹ , the temperature rise of the outer ring is suppressed by 5° C. in the example compared to the comparative example. By using an angular contact ball bearing including a retainer having cutouts in this way, it is possible to suppress the temperature rise of the bearing ring during high-speed rotation.

The rolling bearing of the present invention can prevent the melting of the cage and the seizure of the bearing ring by suppressing the temperature rise due to sliding even at high speed rotation, so it is widely used as a bearing for devices capable of high speed rotation. Available. In particular, it is suitable as an angular contact ball bearing that supports the spindle of a machine tool.

1 angular contact ball bearing 2 inner ring 3 outer ring 4 ball 5 cage 6 ring portion 7 pocket portion 11 angular contact ball bearing 12 inner ring 13 outer ring 14 ball 15 cage 21 spindle unit 22 main shaft 23 inner ring spacer 24 outer ring spacer 25 outer cylinder 26 cooling Liquid passage

Claims (3)

An inner ring and an outer ring which are bearing rings, a plurality of rolling elements arranged between the inner ring and the outer ring, and a retainer for holding the plurality of rolling elements at predetermined intervals in the circumferential direction, A one-side outer ring guide type rolling bearing in which the retainer is guided by the outer ring on one side in the axial direction ,
The retainer is a resin retainer made of synthetic resin, and has an outer ring guide portion that is guided by the outer ring on the outer peripheral surface of the retainer. having a notch formed to have a smaller diameter than the outer diameter of the guide,
A rolling bearing according to claim 1, wherein said notch portion is a recessed groove portion which is not open in the width surface of said retainer, and both sides of said groove portion constitute said outer ring guide portion. An inner ring and an outer ring which are bearing rings, a plurality of rolling elements arranged between the inner ring and the outer ring, and a retainer for holding the plurality of rolling elements at predetermined intervals in the circumferential direction, A one-side inner ring guide type rolling bearing in which the retainer is guided by the inner ring on one side in the axial direction ,
The retainer is a resin retainer made of synthetic resin, and has an inner ring guide portion that is guided by the inner ring on the inner peripheral surface of the retainer. having a notch formed to have a diameter larger than the inner diameter of the inner ring guide,
A rolling bearing according to claim 1, wherein said cutout portion is a recessed groove portion which is not open on the width surface of said retainer, and both sides of said groove portion constitute said inner ring guide portion. 3. A rolling bearing according to claim 1, wherein said rolling bearing is an angular contact ball bearing for supporting a main shaft of a machine tool.

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