JP2018009669A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing in which a load in an axial direction acts as well as a load in a radial direction, which suppresses creep and which reduces a contact surface pressure generating in a mating member by the rolling bearing coming into contact with the mating member.SOLUTION: A rolling bearing 7 includes an inner ring 11, an outer ring 12, a plurality of balls 13 and a cage 14. The inner ring 11 is a rotary ring and the outer ring 12 is a fixed ring. On a fitting surface 22 with a housing 2 in which the outer ring 12 is mounted, an annular groove 32 for creep suppression is formed. Cylindrical surfaces 36a, 37a which can come into contact with the housing 2 are formed on one side in the axial direction and on the other side in the axial direction of the annular groove 32 respectively. The cylindrical surface 36a on the one side in the axial direction which becomes the side in which the balls 13 come into contact with the outer ring 12 by an axial direction load acting on the outer ring 12 and the inner ring 11 is longer in the axial direction than the cylindrical surface 37a on the other side in the axial direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rolling bearing.

  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 that holds the rolling elements. For example, as shown in FIG. 4, in the rolling bearing 90 that supports the rotation shaft 99 in the housing 97, an inner ring 91 is attached by being fitted on the rotation shaft 99, and an outer ring 92 is an inner peripheral surface 98 of the housing 97. Is attached.

  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 “clear fit” state. Therefore, creep (slip in the circumferential direction of the outer ring 92 with respect to the housing 97) is likely to occur between the outer ring 92 and the housing 97 when the rotary shaft 99 is rotating.

  Therefore, a rolling bearing is proposed in which an annular groove 93 is formed in the center of the outer peripheral surface 94 of the outer ring 92 to suppress the occurrence of creep (see Patent Document 1). According to this rolling bearing 90, it is possible to suppress creep that is likely to occur when a large load in the radial direction (radial direction) is applied. The creep that is likely 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.

JP 2006-322579 A

  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 comes into contact with the raceway groove 92a of the outer ring 92 at a position P that is biased to one side in the axial direction (see FIG. 5), and the outer ring 92 has a larger roll on one side in the axial direction than the other side in the axial direction. It will receive a moving body load.

  For this reason, the surface pressure generated when the outer ring 92 comes into contact with the housing 97 becomes higher on one side in the axial direction as shown in FIG. 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 a portion where the contact surface pressure is high. In particular, when the outer ring 92 is made of bearing steel or the like, when the housing 97 is made of a material that is relatively easily worn, such as an aluminum alloy, some measures are required.

  Therefore, the present invention suppresses creep in a rolling bearing in which an axial load acts in addition to a radial load, and reduces the contact surface pressure generated in the mating member by contacting the rolling bearing with the mating member. The purpose is to reduce.

  The present invention comprises an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a cage that holds the plurality of rolling elements, the inner ring and the outer ring, A rolling bearing in which one of them is a rotating ring and the other is a fixed ring, and an annular groove for suppressing creep is formed on a mating surface with a 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 groove, and when the axial load acts on the fixed wheel and the rotating wheel, the rolling element The cylindrical surface on one side in the axial direction which is the side in contact with the fixed ring is longer in the axial direction than the cylindrical surface on the other side in the axial direction.

  According to this rolling bearing, since the annular groove is formed in the fixed ring, it is possible to suppress the occurrence of relative slip between the mating member due to the elastic deformation of the fixed ring and to suppress creep. It becomes possible. Furthermore, when both the radial load and the axial load act on the rolling bearing, the fixed ring has a larger cylindrical surface on the one side in the axial direction where the rolling element load acts more greatly. It becomes possible to disperse and reduce the contact surface pressure generated on one side in the axial direction of the counterpart member.

  In the case of the rolling bearing, the annular groove is formed so as to be biased toward the other side in the axial direction on the fitting surface of the fixed ring. Therefore, it is preferable that the track formed on the fixed ring and in contact with the rolling element is formed to be biased toward the other side in the axial direction of the fixed ring. In this case, in the fixed ring, both the annular groove and the track are located so as to be biased toward the other side in the axial direction. Thereby, the creep suppressing effect by the annular groove can be maintained high.

  According to the present invention, it is possible to suppress creeping of the fixed ring, and it is possible to reduce the contact surface pressure generated in the mating member by dispersing it. 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 housing inner peripheral surface 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 housing inner peripheral surface 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 a rolling bearing according to the present invention. A 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 so as to be rotatable with respect to the housing 2. The rotating shaft 4 has a small-diameter shaft portion 4a to which the 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 axial side of the inner peripheral surface 3 of the housing 2 (hereinafter also referred to as the housing inner peripheral surface 3). The outer ring 12 of the rolling bearing 7 is in contact with the annular portion 5 from the axial direction.

  The rolling bearing 7 includes an inner ring 11 that is externally fitted to the rotary shaft 4, an outer ring 12 that is attached to the inner peripheral surface 3 of the housing, and a plurality of rollers that are interposed between the inner ring 11 and the outer ring 12. Rolling elements and an annular retainer 14 for holding the rolling elements. 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 direction to the other axial side, and the large-diameter shaft portion 4b of the rotating shaft 4 pushes the inner ring 11 from the other axial direction to the one axial side, 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. The rolling bearing 7 supports the rotating shaft 4, and a radial load acts on the rolling bearing 7. Therefore, a combined load of the axial load and the radial load acts on the rolling bearing 7.

In the present embodiment, the inner ring 11 and the rotating shaft 4 are assembled in an “tight fit” state, and the inner ring 11 is fitted in close contact with 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 to the inner peripheral surface 3 of the housing in a “clearance fit” state.
Therefore, creep (slip in the circumferential direction of the outer ring 12 with respect to the housing 2) may occur between the outer ring 12 and the housing 2 when the rotary shaft 4 is rotating together with the inner ring 11. The creep will be described later.

  An inner ring raceway groove (track surface) 11 a on which the balls 13 roll is provided on the outer peripheral surface of the inner ring 11, and an outer ring raceway groove (track surface) on which the balls 13 roll on the inner peripheral surface of the outer ring 12. 12a is provided. The plurality of balls 13 are provided in an 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 roll.

  The cage 14 can hold a plurality of balls 13 at predetermined intervals (equal intervals) along the circumferential direction. For this purpose, the cage 14 has pockets 18 for receiving the balls 13 around it. A plurality are formed along the direction. The cage 14 of the present embodiment includes an annular portion 14a provided on one axial side of the ball 13 and a plurality of column portions 14b extending from the annular portion 14a to the other axial side. Have. A pocket 18 is formed between the pair of column portions 14b and 14b adjacent to each other in the circumferential direction on the other axial side of the annular portion 14a. Note that the cage 14 may have other forms, for example, a configuration having an annular portion on the other side in the axial direction.

  In the rolling bearing 7 of the present embodiment, an outer ring 12 that is a fixed ring is attached to the housing 2 (a mating member), and an outer peripheral surface of the outer ring 12 is fitted with a fitting surface 22 with respect to the housing 2 (inner peripheral surface 3). It has become. An annular groove 32 is formed in the fitting surface 22. The annular groove 32 includes an annular concave groove that is continuous in the circumferential direction, and the cross-sectional shape thereof is the same without changing along the circumferential direction. The annular groove 32 is provided in a region deviated from the axial center of the fitting surface 22 toward the other axial side (left side in the case of FIG. 1). In FIG. 1 and the like showing the annular groove 32, the shape of the annular groove 32 is described deeply for easy explanation. However, the actual depth of the annular groove 32 is extremely small compared to the thickness of the outer ring 12, and The depth of the groove 32 can be, for example, less than 1 mm. The annular groove 32 is not in contact with the housing 2 (inner peripheral surface 3).

  Since the annular groove 32 is provided on the fitting surface 22, the outer ring 12 has cylindrical portions 36 and 37 on both sides in the axial direction of the annular groove 32. The outer peripheral surfaces of the cylindrical portions 36 and 37 are 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 contact the housing 2 (inner peripheral surface 3). As described above, since the annular groove 32 is formed on the fitting surface 22 so as to be displaced to the other side in the axial direction, the first cylindrical surface 36a on the one side in the axial direction has the second cylindrical surface 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 given an axial preload. That is, in addition to the radial load acting on the rolling bearing 7, an axial load also acts. For this reason, the ball 13 contacts the outer ring 12 at a point P1 on one side in the axial direction of the deepest point Q1 in the outer ring raceway groove 12a, and the other side in the axial direction from the deepest point Q2 in 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, a straight line L1 connecting the point P1 and the point P2 that are contact points of the ball 13 with the outer ring 12 and the inner ring 11 is inclined with respect to a center line L0 that passes through the center of the ball 13 and extends in the radial direction. ing. That is, the rolling bearing 7 is subjected to the combined load of the radial load and the axial load as described above, and the direction in which the ball 13 contacts the outer ring 12 and the inner ring 11 by the combined load is 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 this embodiment, the distance from the center line L0 to the side surface 12b on the one axial side 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 axial side of the outer ring 12. That is, the raceway (outer ring raceway groove 12 a) with which the balls 13 are in rolling contact is formed to be biased toward the other side in the axial direction of the outer race 12, and the raceway (inner ring raceway groove 11 a) with which the balls 13 are in rolling contact is formed in the inner ring 11. It is formed to be biased toward the other side in the axial direction.

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

The first creep is likely to occur when a large load in the radial direction (radial direction) is applied to the rolling bearing 7 and is considered to be generated 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 12 a, and at this time, the outer peripheral side of the outer ring directly below the ball 13 is partially elastic. Deform. In addition, in the rolling bearing 7, in addition to a large radial load, an axial load is also acting, and a combined load in the direction of the straight line L1 acts, so that a strain is generated in the radially outer portion of the point P1. So that the outer ring 12 is elastically deformed.
Since the ball 13 moves along the outer ring raceway groove 12a, the outer ring 12 undergoes pulsation deformation (pulsation displacement). Thereby, (when the annular groove 32 is not formed), it is considered that relative slip occurs due to elastic deformation in the contact region of the outer ring 12 with the housing 2, and the first creep is generated by this relative slip.

  The second creep is the same as the first creep in the moving direction (sliding direction) of the outer ring 12, but is likely to occur when the rolling bearing 7 is unloaded. That is, when there is no load, it is considered that the outer ring 12 is rotated by the rotation of the inner ring 11, thereby generating 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 is considered to be caused by swinging along 3.

  And in the rolling bearing 7 of this embodiment, in order to suppress said 1st creep, the annular groove 32 is formed in the fitting surface 22 of the outer ring | wheel 12, and the radial direction outer side of the outer ring raceway groove | channel 12a. Since the annular groove 32 is formed in the fitting surface 22 of the outer ring 12 with respect to the housing 2 in this manner, the occurrence of relative slip due to elastic deformation as described in the first creep generation mechanism is suppressed. And the first creep can be suppressed. That is, when a combined load including a large radial load is applied to the rolling bearing 7, the radially outer region of the outer ring 12 at the point P1 of the outer ring raceway groove 12a is elastically deformed (expanded diameter). However, since the annular groove 32 is formed in the region, elastic deformation (expansion) can be caused mainly in the range of the annular groove 32. For this reason, the range in which the elastically deformed portion and the housing inner peripheral surface 3 are in direct contact with each other can be reduced, and the elastic deformation is not transmitted to the housing 2 (almost). Creep generation is suppressed. As described above, the annular groove 32 becomes the first creep suppressing groove (escape groove).

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

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

  In addition, the ratio of the axial lengths of the first cylindrical surface 36a and the second cylindrical surface 37a is such that when the combined load is applied to the rolling bearing 7, the first cylindrical surface 36a comes into contact with the housing. 2 is preferably set so that the surface pressure (average value) generated in the housing 2 is equal to the surface pressure (average value) generated in the second cylindrical surface 37a. As a result, the contact surface pressure that should increase on one side in the axial direction is also distributed to the other side in the axial direction, and wear of the housing 2 can be effectively prevented.

  Furthermore, in the case of this embodiment, by making the first cylindrical surface 36a wider than the second cylindrical surface 37a, the annular groove 32 is formed to be biased toward the other side in the axial direction on the fitting surface 22 of the outer ring 12. It becomes the composition which becomes. Therefore, as shown in FIG. 1, the outer ring raceway groove 12 a is also formed so as to be biased toward the other side in the axial direction in the outer ring 12. Thereby, in the outer ring 12, both the annular groove 32 and the outer ring raceway groove 12a are configured to be biased to the other side in the axial direction.

  With this configuration, the creep suppression effect by the annular groove 32 can be maintained high. The reason is that, when a radial load is applied to the rolling bearing 7, a high creep suppressing effect can be obtained by forming the annular groove 32 in a portion where the strain due to the elastic deformation of the outer ring 12 increases. That is, when the outer ring 12 is elastically deformed radially outward due to the radial component of the combined load, the strain amount at the outer peripheral portion of the outer ring 12 increases at a portion near the contact point P1 between the ball 13 and the outer ring raceway groove 12a. The amount of strain decreases toward the both sides in the axial direction. Therefore, in order to suppress the first creep as described above, it is only necessary to form the annular groove 32 in a region where the amount of strain increases. For this reason, the annular groove 32 is formed on the other side in the axial direction as in the present embodiment. The outer ring raceway groove 12a may be formed so as to be biased to the other side in the axial direction. As a result, an annular groove 32 is formed in the outer ring 12 in a region where the amount of strain increases. As a result, it is not necessary to contact the housing 2 with a region where the strain amount of the outer ring 12 becomes large, and the first creep due to the pulsation deformation (pulsation 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 a 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. This is a fixed ring fixed (but creeped) 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 may be a fixed ring. 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 together with the housing 2. In this case, the inner ring 11 and the shaft 4 are in a state of clearance fitting, and the inner ring 11 creeps with respect to the shaft 4, so that the fitting surface (inner peripheral surface) of the inner ring 11 with respect to the shaft 4 which is the counterpart member. An annular groove 32 is formed in 21 (similar to the embodiment of FIG. 1). Then, when the axial load acts on the rolling bearing 7 shown in FIG. 3 in addition to the radial load, 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). A cylindrical surface 38a on one side in the axial direction serving as 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, in the inner ring 11, the axial one side where the rolling element load acts greatly is compared with the other axial side. Thus, the area of the cylindrical surface 38a is increased. For this reason, it becomes possible to disperse | distribute and reduce the contact surface pressure which arises in the axial direction one side of the axis | shaft 4. FIG.
Also in the form shown in FIG. 3, the inner ring raceway groove 11 a formed on the inner ring 11 and in contact with the balls 13 is formed in the inner ring 11 so as to be biased toward the other side in the axial direction. Thereby, both the annular groove 32 and the inner ring raceway groove 11a are configured to be offset toward the other side in the axial direction, and the creep suppressing effect by the annular groove 32 can be maintained high.

  1 (FIG. 3), the outer ring raceway groove 12a (inner ring raceway groove 11a) has been described as being formed on the other side in the axial direction in the outer ring 12 (inner ring 11). , (Not shown) may be formed at the axial center position of the outer ring 12 (inner ring 11) without being biased.

The embodiments disclosed above are illustrative in all respects and not restrictive. That is, the rolling bearing of the present invention is not limited to the illustrated form, but may be of another form within the scope of the present invention.
For example, the shape (cross-sectional shape) of the annular groove 32 may be other than the illustrated shape, and may be a concave arc shape other than a rectangle.
In addition to the deep groove ball bearing, the rolling bearing may be an angular 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 a problem.

2: Housing (mating member) 4: Shaft (mating 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 Device 21: Mating surface 22: Mating surface 32: Annular groove 36a: Cylindrical surface 37a: Cylindrical surface 38a: Cylindrical surface 39b: Cylindrical surface

Claims (2)

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 plurality of rolling elements, and one of the inner ring and the outer ring A rolling bearing in which 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,
A cylindrical surface capable of contacting the mating member is formed on each of the annular groove on one axial side and the other axial side,
When the axial load is applied to the fixed wheel and the rotating wheel, the cylindrical surface on one side in the axial direction on which the rolling element comes into contact with the fixed wheel is more axial than the cylindrical surface on the other side in the axial direction. Rolling bearings that are long in the direction.   The rolling bearing according to claim 1, wherein the raceway formed on the fixed ring and in contact with the rolling elements is formed to be biased toward the other side in the axial direction of the fixed ring.

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