JP6790535B2 - Rolling bearing - Google Patents

Description

The present invention relates to rolling bearings.

Many rolling bearings are used in various industrial equipment. The rolling bearing includes an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a cage for holding the rolling elements. For example, as shown in FIG. 4, in the rolling bearing 90 that supports the rotating shaft 99 in the housing 97, the inner ring 91 is fitted and attached to the rotating shaft 99, and the outer ring 92 is attached to the inner peripheral surface 98 of the housing 97. It is attached to.

In such a rolling bearing 90, the inner ring 91 and the rotating shaft 99 are assembled in a "tight fit" state, whereas the outer ring 92 and the housing 97 are often assembled in a "gap fit" state. Therefore, creep (slip of the outer ring 92 with respect to the housing 97 in the circumferential direction) is likely to occur between the outer ring 92 and the housing 97 in the used state where the rotating shaft 99 is rotating.

Therefore, a rolling bearing in which an annular groove 93 for suppressing creep generation is formed in the center of the outer peripheral surface 94 of the outer ring 92 has been proposed (see Patent Document 1). According to the rolling bearing 90, it is possible to suppress creep that tends to occur when a large load in the radial direction (radial direction) is applied. The creep that tends to occur when such a load is applied is a creep in which the outer ring 92 slowly slides in the same direction as the bearing rotation direction.

Japanese Unexamined Patent Publication No. 2006-322579

As described above, by forming the annular groove 93 on the outer peripheral surface 94 of the outer ring 92, it is possible to suppress the creep that occurs when a large radial load is applied. However, not only the radial load but also the axial load may act on the rolling bearing 90. In this case, the ball 95 contacts the raceway groove 92a of the outer ring 92 at a position P biased to one side in the axial direction (see FIG. 5), and the outer ring 92 rolls larger on one side in the axial direction than on the other side in the axial direction. It will receive a moving body load.

Therefore, as shown in FIG. 5, the surface pressure generated by the contact of the outer ring 92 in the housing 97 increases on one side in the axial direction. If the outer ring 92 creeps even a little while the contact surface pressure generated in the housing 97 is high, the housing 97 may be worn at the portion where the contact surface pressure is high. In particular, when the outer ring 92 is made of bearing steel or the like, while the housing 97 is made of a material that is relatively easily worn, such as made of an aluminum alloy, some measures are required.

Therefore, according to the present invention, in a rolling bearing in which an axial load is applied in addition to a radial load, creep is suppressed and the contact surface pressure generated in the mating member is reduced by the rolling bearing coming into contact with the mating member. The purpose is to reduce.

The present invention includes an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and a cage for holding the plurality of balls , and the inner ring is in rolling contact with the balls. The outer ring has a track formed of a concave groove to which the ball rolls and contacts , and one of the inner ring and the outer ring is a rotating wheel and the other is a fixed ring. An annular groove for suppressing creep is formed on the mating surface of the bearing with the mating member to which the fixed ring is attached, and the mating member is formed on one side in the axial direction and the other side in the axial direction of the annular groove. A cylindrical surface that can be contacted with the fixed ring is formed, and the cylindrical surface on one side in the axial direction on which the ball comes into contact with the fixed ring due to an axial load acting on the fixed wheel and the rotating wheel is formed. , Axial longer than the cylindrical surface on the other side in the axial direction.

According to this rolling bearing, since the fixed ring is formed with an annular groove, it is possible to suppress the occurrence of relative slippage with the mating member due to the elastic deformation of the fixed ring, and it is possible to suppress creep. It will be possible. Further, when both the radial load and the axial load act on the rolling bearing, the area of the cylindrical surface becomes larger on one side in the axial direction in which the rolling element load acts on the fixed wheel. It is possible to disperse and reduce the contact surface pressure generated on one side of the mating member in the axial direction.

Further, in the case of the rolling bearing, the annular groove is formed unevenly on the other side in the axial direction on the fitting surface of the fixed ring. Therefore, the trajectory the formed in the fixed ring contacts the ball is rolling is preferably formed biased toward the other axial direction in the fixed ring. In this case, in the fixed wheel, both the annular groove and the raceway are positioned so as to be biased to the other side in the axial direction. As a result, the creep suppressing effect of the annular groove can be maintained high.

According to the present invention, it is possible to suppress creep of the fixed wheel, and it is possible to disperse and reduce the contact surface pressure generated in the mating member. As a result, wear on the mating member can be suppressed.

It is sectional drawing which shows one Embodiment of the rolling bearing of this invention. It is explanatory drawing which shows the surface pressure distribution which acts on the inner peripheral surface of a housing in the rolling bearing shown in FIG. It is sectional drawing which shows the other form of a rolling bearing. It is sectional drawing of the conventional rolling bearing. It is explanatory drawing which shows the surface pressure distribution which acts on the inner peripheral surface of a housing in the conventional rolling bearing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing an embodiment of the rolling bearing of the present invention. The rolling bearing 7 shown in FIG. 1 is provided in a rotating device having a housing 2 and a rotating shaft 4, and supports the rotating shaft 4 rotatably with respect to the housing 2. The rotating shaft 4 has a small-diameter shaft portion 4a to which a rolling bearing 7 is fitted and attached, and a large-diameter shaft portion 4b having an outer diameter larger than that of the small-diameter shaft portion 4a. The inner ring 11 of the rolling bearing 7 is in contact with the large diameter shaft portion 4b from the axial direction. An annular portion 5 is provided on one side of the inner peripheral surface 3 of the housing 2 (hereinafter, also referred to as a housing inner peripheral surface 3) in the axial direction. The outer ring 12 of the rolling bearing 7 is in contact with the annular portion 5 from the axial direction.

A plurality of rolling bearings 7 are interposed between the inner ring 11 attached to the rotating shaft 4 and the outer ring 12 attached to the inner peripheral surface 3 of the housing, and the inner ring 11 and the outer ring 12. The rolling elements of the above and an annular cage 14 for holding these rolling elements are provided. The rolling element of the present embodiment is a ball 13, and the rolling bearing 7 shown in FIG. 1 is a deep groove ball bearing.

The annular portion 5 of the housing 2 pushes the outer ring 12 from one axial side to the other axial direction, and the large diameter shaft portion 4b of the rotating shaft 4 pushes the inner ring 11 from the other axial side to the other axial direction. The annular portion 5, the rolling bearing 7, and the rotating shaft 4 are provided, and the rolling bearing 7 is in a state where an axial load (preload) is applied. Then, the rolling bearing 7 supports the rotating shaft 4, so that a load in the radial direction acts on the rolling bearing 7. Therefore, a combined load of an axial load and a radial load acts on the rolling bearing 7.

In the present embodiment, the inner ring 11 and the rotating shaft 4 are assembled in a "tight-fitting" state, and the inner ring 11 is closely fitted to the rotating shaft 4 and can rotate integrally with the rotating shaft 4. On the other hand, the outer ring 12 is attached to the housing 2 in a fixed state, and the outer ring 12 is assembled on the inner peripheral surface 3 of the housing in a “gap fit” state.
Therefore, creep (sliding of the outer ring 12 with respect to the housing 2 in the circumferential direction) may occur between the outer ring 12 and the housing 2 in the used state where the rotating shaft 4 is rotating together with the inner ring 11. The creep will be described later.

An inner ring raceway groove (track surface) 11a on which the ball 13 rolls is provided on the outer peripheral surface of the inner ring 11, and an outer ring raceway groove (track surface) on which the ball 13 rolls is provided on the inner peripheral surface of the outer ring 12. 12a is provided. The plurality of balls 13 are provided in the annular space 15 between the inner ring 11 and the outer ring 12, and when the rolling bearing 7 rotates (when the inner ring 11 rotates), these balls 13 are held by the cage 14. The inner ring raceway groove 11a and the outer ring raceway groove 12a are rolled.

The cage 14 can hold a plurality of balls 13 at predetermined intervals (equal intervals) along the circumferential direction, and for this purpose, the cage 14 has a pocket 18 for accommodating the balls 13. Multiple pieces are formed along the direction. The cage 14 of the present embodiment has an annular portion 14a provided on one side in the axial direction of the ball 13 and a plurality of pillar portions 14b extending from the annular portion 14a on the other side in the axial direction. Have. The pocket 18 is located on the other side of the annular portion 14a in the axial direction and is adjacent to each other in the circumferential direction between the pair of pillar portions 14b and 14b. The cage 14 may have another form, and for example, the cage 14 may have a ring portion on the other side in the axial direction.

In the rolling bearing 7 of the present embodiment, the outer ring 12 which is a fixed ring is attached to the housing 2 (the mating member), and the outer peripheral surface of the outer ring 12 is the fitting surface 22 with respect to the housing 2 (inner peripheral surface 3). It has become. An annular groove 32 is formed on the fitting surface 22. The annular groove 32 is composed of an annular concave groove continuous in the circumferential direction, and the cross-sectional shape thereof does not change along the circumferential direction and is the same. The annular groove 32 is provided in a region biased from the central portion of the fitting surface 22 in the axial direction to the other side in the axial direction (left side in the case of FIG. 1). In addition, in FIG. 1 and the like showing the annular groove 32, the shape is described deeply for easy explanation, but the actual depth of the annular groove 32 is extremely small compared to the thickness of the outer ring 12, and is annular. The depth of the groove 32 can be, for example, less than 1 mm. The annular groove 32 is in non-contact with the housing 2 (inner peripheral surface 3).

Since the fitting surface 22 is provided with the annular groove 32, the outer ring 12 has cylindrical portions 36 and 37 on both sides of the annular groove 32 in the axial direction. The outer peripheral surfaces of the cylindrical portions 36 and 37 are formed of cylindrical surfaces centered on the bearing center line C0 of the rolling bearing 7, and the outer peripheral surfaces of the cylindrical portions 36 and 37 are hereinafter referred to as cylindrical surfaces 36a and 37a. As shown in FIG. 1, in the cross section including the bearing center line C0, the cylindrical surfaces 36a and 37a have a linear shape parallel to the bearing center line C0. These cylindrical surfaces 36a and 37a are surfaces that can come into contact with the housing 2 (inner peripheral surface 3). As described above, since the annular groove 32 is formed in the fitting surface 22 so as to be displaced to the other side in the axial direction, the first cylindrical surface 36a on one side in the axial direction is the second cylindrical surface 36a on the other side in the axial direction. It is longer in the axial direction than the cylindrical surface 37a (Y1> Y2).

As described above, the rolling bearing 7 is preloaded in the axial direction. That is, in addition to the radial load acting on the rolling bearing 7, the axial load also acts on the rolling bearing 7. Therefore, the ball 13 contacts the outer ring 12 at a point P1 axially one side of the deepest point Q1 of the outer ring raceway groove 12a, and is axially the other side of the deepest point Q2 of the inner ring raceway groove 11a. It contacts the inner ring 11 at the point P2 on the side. In the cross section shown in FIG. 1, the straight line L1 connecting the points P1 and P2, which are the contact points of the balls 13 with respect to the outer ring 12 and the inner ring 11, is inclined with respect to the center line L0 extending in the radial direction through the center of the balls 13. ing. That is, as described above, a combined load of the radial load and the axial load acts on the rolling bearing 7, and the direction in which the ball 13 comes into contact with the outer ring 12 and the inner ring 11 due to this combined load is described above. The direction of the straight line L1 is inclined with respect to the center line L0, and the rolling bearing 7 has a contact angle.

The radial center line L0 is a straight line passing through the center of the ball 13, and in the present embodiment, the distance from the center line L0 to the side surface 12b on one side in the axial direction of the outer ring 12 is from the center line L0. It is larger than the distance to the side surface 12c on the other side in the axial direction of the outer ring 12. That is, the track (outer ring raceway groove 12a) in which the ball 13 rolls and contacts is formed unevenly on the other side in the axial direction in the outer ring 12, and the track (inner ring raceway groove 11a) in which the ball 13 rolls and contacts is formed in the inner ring 11. It is formed unevenly on the other side in the axial direction.

Here, the creep that occurs between the housing 2 and the outer ring 12 will be described. There are three possible creeps that may occur in the rolling bearing 7. In the case of this embodiment, the following bearing rotation direction is the rotation direction of the inner ring 11 which is a rotating wheel.
-First creep: Creep in which the outer ring 12 slides slowly in the same direction as the bearing rotation direction-Second creep: Creep in which the outer ring 12 slides quickly in the same direction as the bearing rotation direction-Third creep: Reverse the bearing rotation direction Creep that the outer ring 12 slides in the direction

The first creep is likely to occur when a large radial (radial direction) load is applied to the rolling bearing 7, and is considered to occur by the following mechanism. That is, when a large radial load is applied to the rolling bearing 7, the ball 13 receives a high load and passes through the outer ring raceway groove 12a, and at that time, the outer ring outer peripheral side directly below the ball 13 is partially elastic. Deform. In the rolling bearing 7, in addition to the large load in the radial direction, a load in the axial direction also acts, and the combined load in the direction of the straight line L1 acts to cause strain in the portion outside the radial direction of the point P1. The outer ring 12 is elastically deformed so that
Then, since the ball 13 moves along the outer ring raceway groove 12a, the outer ring 12 undergoes pulsating deformation (pulsating displacement). As a result, relative slip occurs due to elastic deformation in the contact region of the outer ring 12 with the housing 2 (when the annular groove 32 is not formed), and it is considered that the first creep occurs due to this relative slip.

The second creep is likely to occur when the rolling bearing 7 is unloaded, although the moving direction (sliding direction) of the outer ring 12 is the same as that of the first creep. That is, when there is no load, it is considered that the rotation of the inner ring 11 causes the outer ring 12 to rotate, which causes a second creep.

In the third creep, the moving direction (sliding direction) of the outer ring 12 is opposite to that of the first and second creeps. This means that, for example, the outer ring 12 has an inner peripheral surface of the housing due to an eccentric load in the radial direction. It is considered that it occurs by swinging around along 3.

Then, in the rolling bearing 7 of the present embodiment, in order to suppress the first creep, an annular groove 32 is formed on the fitting surface 22 of the outer ring 12 on the radial outer side of the outer ring raceway groove 12a. By forming the annular groove 32 on the fitting surface 22 of the outer ring 12 with respect to the housing 2 in this way, the occurrence of relative slippage due to elastic deformation as described in the first creep generation mechanism described above is suppressed. It is possible to suppress the first creep. That is, when a combined load including a large radial load is applied to the rolling bearing 7, the region outside the radial direction of the point P1 of the outer ring raceway groove 12a in the outer ring 12 is elastically deformed (diameter expanded). However, since the annular groove 32 is formed in the region, elastic deformation (diameter expansion) can be caused mainly in the range of the annular groove 32. Therefore, the range in which the elastically deformed portion and the inner peripheral surface 3 of the housing come into direct contact can be reduced, and the elastic deformation is (almost) not transmitted to the housing 2, and the first one between the outer ring 12 and the housing 2 Creep generation is suppressed. From the above, the annular groove 32 becomes the first groove for suppressing creep (relief groove).

Then, in the rolling bearing 7 of the present embodiment, as described above, the ball 13 contacts the outer ring 12 at a position (point P1) biased to one side in the axial direction (right side in FIG. 1), so that the outer ring 12 is in contact with the outer ring 12. , A larger rolling element load is received on one side in the axial direction than on the other side in the axial direction. Therefore, in the outer ring 12, the first cylindrical surface 36a on one side in the axial direction is made longer in the axial direction than the second cylindrical surface 37a on the other side in the axial direction (Y1> Y2). Therefore, the area of the first cylindrical surface 36a on one side in the axial direction is larger than that of the second cylindrical surface 37a on the other side in the axial direction. That is, the contact area with the inner peripheral surface 3 of the housing is wider on the first cylindrical surface 36a than on the second cylindrical surface 37a.

Therefore, when both the radial load and the axial load act on the rolling bearing 7, as shown in FIG. 2, the contact surface pressure generated on one side of the housing 2 in the axial direction has a wide contact area. It can be dispersed on one side in the axial direction, and the contact surface pressure can be reduced as a whole on one side in the axial direction. As a result, even if a small amount of creep occurs, wear in the housing 2 can be suppressed. In particular, in the present embodiment, the outer ring 12 is made of bearing steel, whereas the housing 2 is made of an aluminum alloy and is easily worn at a portion where the surface pressure is high. However, by widening the first cylindrical surface 36a, , It is possible to prevent such wear.

Further, the ratio of the axial lengths of the first cylindrical surface 36a and the second cylindrical surface 37a is such that when a combined load is applied to the rolling bearing 7, the first cylindrical surface 36a comes into contact with the housing. It is preferable to set the surface pressure (average value) generated in No. 2 to be equal to the surface pressure (average value) generated in the housing 2 when the second cylindrical surface 37a comes into contact with each other. As a result, the contact surface pressure that should increase on one side in the axial direction is dispersed on the other side in the axial direction, and it is possible to effectively prevent wear of the housing 2.

Further, in the case of the present embodiment, by making the first cylindrical surface 36a wider than the second cylindrical surface 37a, the annular groove 32 is formed unevenly on the other side in the axial direction on the fitting surface 22 of the outer ring 12. The configuration is as follows. Therefore, as shown in FIG. 1, the outer ring raceway groove 12a is also formed in the outer ring 12 so as to be biased toward the other side in the axial direction. As a result, in the outer ring 12, both the annular groove 32 and the outer ring raceway groove 12a are positioned so as to be biased toward the other side in the axial direction.

With this configuration, the creep suppressing effect of the annular groove 32 can be maintained high. The reason is that when a radial load is applied to the rolling bearing 7, an annular groove 32 is formed in a portion where the strain due to the elastic deformation of the outer ring 12 is large, so that a high creep suppressing effect can be obtained. That is, when the outer ring 12 is elastically deformed radially outward due to the radial component of the combined load, the amount of strain in the outer peripheral portion of the outer ring 12 becomes large in the portion near the contact point P1 between the ball 13 and the outer ring raceway groove 12a. The amount of strain decreases toward both sides in the axial direction. Therefore, in order to suppress the first creep as described above, it is sufficient to form the annular groove 32 in the region where the strain amount becomes large, and therefore, as in the present embodiment, the annular groove 32 is on the other side in the axial direction. If the outer ring raceway groove 12a is also formed in a biased manner, the outer ring raceway groove 12a may also be formed in a biased manner on the other side in the axial direction. As a result, the annular groove 32 is formed in the region where the strain amount is large in the outer ring 12. As a result, it is not necessary to bring the region where the strain amount of the outer ring 12 becomes large into contact with the housing 2, and the first creep caused by the pulsating deformation (pulsating displacement) of the outer ring 12 is suppressed.

In the embodiment (see FIG. 1), the inner ring 11 is a rotating wheel that rotates integrally with the mating member (rotating shaft 4) to which the inner ring 11 is attached, and the outer ring 12 is attached to the outer ring 12. A fixed wheel that is fixed (although it creeps) to the mating member (housing 2).
However, in the present invention, one of the inner ring 11 and the outer ring 12 may be a rotating wheel and the other is a fixed ring, and contrary to the form shown in FIG. 1, the shaft 4 is used as shown in FIG. The attached inner ring 11 may be a fixed ring, and the outer ring 12 may be a rotating wheel that rotates integrally with the housing 2. In this case, the space between the inner ring 11 and the shaft 4 is set to be a clearance fitting state, and the inner ring 11 creeps with respect to the shaft 4. Therefore, the fitting surface (inner peripheral surface) of the inner ring 11 with respect to the shaft 4 which is a mating member. An annular groove 32 is formed in 21 (similar to the form of FIG. 1). Then, in addition to the radial load, the axial load acts on the rolling bearing 7 shown in FIG. 3, so that the ball 13 comes into contact with the inner ring 11 which is a fixed ring with a large load (that is, the rolling element load is large). The cylindrical surface 38a on one side in the axial direction, which is the acting side), is longer in the axial direction than the cylindrical surface 39b on the other side in the axial direction.

As a result, when both the radial load and the axial load act on the rolling bearing 7, the one side in the axial direction on which the rolling element load acts significantly on the inner ring 11 is compared with the other side in the axial direction. As a result, the area of the cylindrical surface 38a becomes wider. Therefore, it is possible to disperse and reduce the contact surface pressure generated on one side of the shaft 4 in the axial direction.
Further, also in the form shown in FIG. 3, the inner ring raceway groove 11a formed in the inner ring 11 and in which the balls 13 roll and contact is formed in the inner ring 11 so as to be biased toward the other side in the axial direction. As a result, both the annular groove 32 and the inner ring raceway groove 11a are positioned unevenly on the other side in the axial direction, and the creep suppressing effect of the annular groove 32 can be maintained high.

In each of the above-described embodiments shown in FIG. 1 (FIG. 3), the case where the outer ring raceway groove 12a (inner ring raceway groove 11a) is formed in the outer ring 12 (inner ring 11) so as to be biased toward the other side in the axial direction has been described. , (Not shown) may be formed at the axial center position of the outer ring 12 (inner ring 11) without bias.

The embodiments disclosed as described above are exemplary in all respects and are not restrictive. That is, the rolling bearing of the present invention is not limited to the illustrated form, and may have other forms within the scope of the present invention.
For example, the shape (cross-sectional shape) of the annular groove 32 may be a shape other than the shape shown in the drawing, and may be a concave arc shape or the like in addition to the rectangular shape.
Further, the rolling bearing may be an angular contact ball bearing other than the deep groove ball bearing, and the rolling element may be other than a ball, and may be a cylindrical roller or a tapered roller.
Further, the rolling bearing of the present invention can be applied to various rotating devices, and is particularly suitable for rotating devices in which creep is an issue.

2: Housing (counterpart member) 4: Shaft (partner member) 7: Rolling bearing 11: Inner ring 11a: Inner ring raceway groove (track) 12: Outer ring 12a: Outer ring raceway groove (track) 13: Ball (rolling element) 14: Holding Instrument 21: Fitting surface 22: Fitting surface 32: Circular groove 36a: Cylindrical surface 37a: Cylindrical surface 38a: Cylindrical surface 39b: Cylindrical surface

Claims (1)

The inner ring is provided with an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and a cage for holding the plurality of balls , and the inner ring is formed from a concave groove in which the balls roll and come into contact with each other. The outer ring is a rolling bearing having a raceway formed of a concave groove in which the ball rolls and contacts , and one of the inner ring and the outer ring is a rotating wheel and the other is a fixed ring. ,
An annular groove for suppressing creep is formed on the mating surface with the mating member to which the fixed ring is attached.
Cylindrical surfaces that can come into contact with the mating member are formed on one side in the axial direction and the other side in the axial direction of the annular groove.
The cylindrical surface on one side in the axial direction on which the ball comes into contact with the fixed ring due to the action of an axial load on the fixed ring and the rotating wheel is axially more axial than the cylindrical surface on the other side in the axial direction. in rather long,
A rolling bearing in which the raceway formed on the fixed wheel and in which the ball rolls and contacts is formed unevenly on the other side in the axial direction in the fixed wheel .

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