JP2022001781A - Roller bearing for wave gear device - Google Patents

Abstract

To provide a roller bearing for a wave gear device which can prevent a crack of an outer ring.SOLUTION: A roller bearing 4 for a wave gear device 1 is interposed between an elliptic cam 3 and a flex spline 5. The roller bearing 4 comprises an outer ring 42, a plurality of rollers 44 and a cage 43. The outer ring 42 is constituted so as to be elastically deformable. The cage 43 has a pair of annular parts 431 which oppose the plurality of rollers 44 from both sides in an axial direction, and a plurality of column parts arranged between the pair of annular parts 431 in a peripheral direction at prescribed intervals. Pockets for rollingly holding the plurality of rollers 44 are formed between the plurality of column parts. The outer ring 42 has opposing protrusions 422a opposing end faces 431a of the pair of annular parts 431 at remote sides at both end parts in an axial direction. The opposing protrusions 422a are formed at a part of the outer ring 42 in a peripheral direction, and formed so as to protrude to an internal peripheral side rather than regions of the outer ring 42 located at both sides in the peripheral direction.SELECTED DRAWING: Figure 3

Description

The present invention relates to roller bearings for strain wave gearing.

Conventionally, a strain wave gearing device, which is also called a harmonic drive (registered trademark), is widely used as a speed reducer for, for example, an industrial robot, a machine tool, or a transport device because of its characteristics that a large reduction ratio can be obtained and backlash is small. ..

As disclosed in Patent Document 1, a strain wave gearing device includes a wave generator, a flexspline with external teeth, and a circular spline with internal teeth. The wave generator comprises an elliptical cam and a ball bearing fitted externally to the elliptical cam. A rotary input shaft is attached to the elliptical cam. Further, a flex spline is externally fitted to the ball bearing. The flexspline is equipped with a rotary output shaft that takes out a rotation that is slower than the rotation of the input rotary shaft.

The ball bearing and the flexspline are elastically deformed into an elliptical shape by being expanded by the elliptical cam in the direction of the long axis of the cam in which the long axis of the elliptical cam extends. Then, in the ball bearing and the flexspline, the elastic deformation is repeated so that the portion expanded by the elliptical cam shifts in the rotation direction as the elliptical cam rotates. Both ends of the flexspline external teeth in the longitudinal direction of the cam mesh with the internal teeth of the circular spline. The number of internal teeth of the circular spline is greater than the number of external teeth of the flexspline. As a result, the strain wave gearing is configured so that the flexspline rotates by the difference in the number of teeth between the outer teeth of the elliptical cam and the inner teeth of the circular spline for each rotation of the elliptical cam.

Here, the ball bearings used in the strain wave gearing described in Patent Document 1 all include an inner ring made of a metal such as bearing steel, an outer ring, and a plurality of balls. The inner ring is fitted on an elliptical cam and has a circumferential inner raceway groove on the outer peripheral portion and inner shoulders adjacent to both sides of the inner raceway groove in the axial direction. The outer ring is fitted in the flexspline and has a circumferential outer track groove on the inner circumference and outer shoulders adjacent to both sides of the outer track groove in the axial direction. The plurality of balls are arranged at equal intervals in the circumferential direction in the rolling space between the inner orbital groove and the outer orbital groove.

Japanese Unexamined Patent Publication No. 2018-200112

Bearings used in strain wave gearing are loaded only at both ends in the longitudinal direction of the cam where the external teeth of the flexspline and the internal teeth of the circular spline mesh. Therefore, in order to secure the rigidity of the bearing used in the strain wave gearing, it is necessary to provide a large number of rolling elements so that the rolling elements are closely arranged in the circumferential direction. Therefore, when a ball bearing having a rolling element as a ball is used in the strain wave gearing as described in Patent Document 1, there is a concern that the productivity of the ball bearing may decrease. That is, in manufacturing ball bearings, a method of introducing a plurality of balls into the rolling space from between the inner shoulder of the inner ring and the outer shoulder of the outer ring can be considered. In addition, it becomes necessary to push the ball into the rolling space while elastically expanding the outer shoulder, which may reduce productivity due to an increase in work load.

Therefore, as a bearing used in the strain wave gearing, it is conceivable to adopt a roller bearing that can be assembled without press-fitting even if a large number of rolling elements are provided. As a roller bearing, the inner peripheral surface projects from the entire circumference of each of the cylindrical portion constituting the rolling surface and both ends of the cylindrical portion in the axial direction toward the inner peripheral side, and faces both end surfaces of the roller in the axial direction. Some have an outer ring with a pair of bearings. In the roller bearing, a large number of rollers are arranged at equal intervals in the circumferential direction on the rolling surface of the outer ring, and the intervals are maintained by a cage that holds each roller. A cylindrical inner ring attached to the rotating shaft is inserted on the inner peripheral side of each roller. In manufacturing such a roller bearing, for example, a cage is first arranged on the inner peripheral side of the outer ring, rollers are inserted into each pocket of the cage, and an inner ring is inserted on the inner peripheral side of a large number of rollers. This makes it possible to easily manufacture a roller bearing having a large number of rollers without requiring press-fitting.

However, in roller bearings for strain wave gearing, the outer ring repeats elastic deformation so that the portion expanded by the elliptical cam shifts in the rotational direction as the elliptical cam rotates. Therefore, when the flange portion is formed on the entire circumference of the outer ring, stress may be concentrated around the flange portion of the outer ring and crack may occur around the flange portion of the outer ring unless special measures are taken.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a roller bearing for a wave gear device capable of preventing cracking of an outer ring.

In order to achieve the above object, the present invention intervenes between an elliptical cam and a flexspline having external teeth that mesh with the internal teeth of the circular spline at both ends of the elliptical cam in the longitudinal direction. A roller bearing for a gear device, which is an elastically deformable outer ring fitted in the flexspline, a plurality of rollers arranged on the rolling surface of the outer ring, and the plurality of rollers from both sides in the axial direction. It has a pair of annular portions facing each other and a plurality of pillar portions arranged at predetermined intervals in the circumferential direction between the pair of annular portions, and a plurality of rollers can be freely rolled between the plurality of pillar portions. The outer ring comprises a cage formed with a holding pocket, each of which has opposed protrusions at both ends in the axial direction, which face each other on the far-flung ends of the pair of annular portions. The facing protrusions are formed in a part of the outer ring in the circumferential direction, and are formed so as to project toward the inner circumference of the outer ring so as to protrude from the portions located on both sides of the facing protrusions in the circumferential direction. Provided are roller bearings for strain wave gearing.

According to the roller bearing for a wave gear device according to the present invention, it is possible to provide a roller bearing for a wave gear device capable of preventing the outer ring from cracking.

It is a front view of the wave gear device in 1st Embodiment. FIG. 1 is a cross-sectional view taken along the line II-II. FIG. 1 is an enlarged view of the periphery of the recess in FIG. FIG. 2 is an enlarged view of the periphery of the recess in FIG. It is a perspective view of a cage and a plurality of rollers in the first embodiment. It is a front view of the wave gear device in 2nd Embodiment. 6 is an enlarged view of the periphery of the facing protrusion in FIG. 6.

[First Embodiment]
The first embodiment of the present invention will be described with reference to FIGS. 1 to 5. It should be noted that the embodiments described below are shown as suitable specific examples for carrying out the present invention, and there are some parts that specifically exemplify various technically preferable technical matters. , The technical scope of the present invention is not limited to this specific aspect.

(Strain wave gearing 1)
FIG. 1 is a front view of the strain wave gearing device 1 of the present embodiment. FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

The present embodiment relates to a strain wave gearing device 1 provided with a roller bearing 4. The wave gear device 1 constitutes, for example, a speed reducer used in an industrial robot, a machine tool, or a transfer device, and is also referred to as a harmonic drive (registered trademark). As shown in FIGS. 1 and 2, the strain wave gearing device 1 includes a wave generator 2, a flexspline 5, and a circular spline 6.

The wave generator 2 includes an elliptical cam 3 and a roller bearing 4. As shown in FIG. 1, the elliptical cam 3 has an elliptical shape when viewed from the axial direction. The long axis direction of the elliptical cam 3 is changed as the elliptical cam 3 rotates, but in FIG. 1, the vertical direction of the paper surface is the long axis direction LD of the elliptical cam 3, and the left and right direction of the paper surface is the short axis direction SD. It shows the state of becoming. The elliptical cam 3 is provided with a fitting hole 31 for fitting a rotation input shaft such as a rotation shaft of a motor. Hereinafter, the term LD in the long axis direction means the direction in which the long axis of the elliptical cam 3 extends, and the term SD in the short axis direction means the direction in which the short axis of the elliptical cam 3 extends. And. Further, the term simply axial direction means the axial direction of the input rotation shaft fitted into the fitting hole 31 of the elliptical cam 3.

A needle roller bearing (hereinafter referred to as "needle roller bearing 4") as a roller bearing 4 is externally fitted on the outer peripheral portion of the elliptical cam 3. The needle roller bearing 4 includes an annular inner ring 41 fitted to the outer peripheral surface of the elliptical cam 3, an annular outer ring 42 arranged concentrically with the inner ring 41 on the outer peripheral side of the inner ring 41, and an inner ring 41. A plurality of needle-shaped rollers 44 arranged in a rolling space surrounded by an inner ring rolling surface 411 and an outer ring rolling surface 421a of the outer ring 42, and a plurality of needle-shaped rollers 44 at intervals of the plurality of needle-shaped rollers 44. It is provided with a cage 43 for holding while maintaining.

The inner ring 41 and the outer ring 42 are made of a metal such as bearing steel, and are formed so that the thickness in the radial direction is thin enough to be elastically deformed in the radial direction. The inner ring 41 and the outer ring 42 are formed in a perfect circle in a free state, but are elastically deformed into an elliptical shape along the outer peripheral surface of the elliptical cam 3 by being fitted onto the elliptical cam 3. Hereinafter, when the needle roller bearing 4 is described, unless otherwise specified, the needle roller bearing 4 in a state of being externally fitted to the elliptical cam 3 will be described.

The inner ring 41 is formed in a cylindrical shape in which the cross-sectional shape orthogonal to the axial direction is an elliptical shape elongated in the long axis direction LD. The outer peripheral surface of the inner ring 41 constitutes the inner ring rolling surface 411. A large number of needle-shaped rollers 44 are arranged at equal intervals in the circumferential direction on the inner ring rolling surface 411.

The needle-shaped roller 44 is formed in a columnar shape long in the axial direction, and has an elongated shape having an outer diameter of 6 mm or less and a ratio of the length in the axial direction to the outer diameter of 3 or more and 10 or less. The circumferential spacing of the plurality of needle rollers 44 is maintained by the cage 43.

FIG. 5 is a perspective view of the cage 43 and a plurality of rollers (needle-shaped rollers 44). As shown in FIG. 5, the cage 43 is formed by forming a resin into a cylindrical shape. The cage 43 has a pair of annular portions 431 facing the plurality of needle-shaped rollers 44 from both sides in the axial direction, and a plurality of pillar portions 432 arranged at predetermined intervals in the circumferential direction between the pair of annular portions 431. A pocket 433 is formed between the plurality of pillar portions 432 to rotatably hold the plurality of needle-shaped rollers 44. The end faces 431a of the pair of annular portions 431 opposite to each other in the axial direction are formed in an annular shape and in a planar shape orthogonal to the axial direction.

As shown in FIG. 1, the cage 43 is located so that the entire circumference of the inner peripheral edge is separated from the inner ring 41 on the outer peripheral side, and the entire circumference of the outer peripheral edge is separated from the outer ring 42 on the inner peripheral side. positioned. As a result, the cage 43 is maintained in a substantially perfect circle without receiving the load from the inner ring 41 and the outer ring 42 even when the needle roller bearing 4 is externally fitted to the elliptical cam 3. In a state where the needle roller bearing 4 is externally fitted to the elliptical cam 3, both ends of the LD in the long axis direction of the cage 43 are arranged at positions relatively close to the inner ring 41 stretched toward the outer peripheral side, while holding. Both ends of the SD in the short axis direction of the vessel 43 are arranged at positions relatively far from the inner ring 41. Although not shown, the cage 43 is formed by combining two parts divided into two at two points in the circumferential direction, for example, in order to improve the ease of assembling to the outer ring 42. An outer ring 42 is arranged on the outer peripheral side of the cage 43 and the plurality of needle-shaped rollers 44.

FIG. 3 is an enlarged view of the periphery of the recess 423 of FIG. FIG. 4 is an enlarged view of the periphery of the recess 423 of FIG. As shown in FIGS. 3 and 4, the outer ring 42 has a cylindrical portion 421 having an elliptical cross section whose inner peripheral surface constitutes the outer ring rolling surface 421a, and the entire circumferences of both ends in the axial direction of the tubular portion 421. It has a flange portion 422 protruding from the inner peripheral side toward the inner peripheral side. In the tubular portion 421, the outer ring rolling surface 421a is radially opposed to the inner ring rolling surface 411 via the cage 43 and the plurality of needle-shaped rollers 44, and the plurality of needle-shaped rollers 44 roll the inner ring. It rolls between the surface 411 and the outer ring rolling surface 421a. In the present embodiment, the pair of flange portions 422 have the same shape as each other, and unless otherwise specified, one flange portion 422 will be described.

As shown in FIG. 1, the flange portion 422 is formed in an annular shape, and has recesses 423 formed from the inner peripheral end toward the outer peripheral side at a plurality of locations in the circumferential direction. In this embodiment, recesses 423 are formed at four points of the flange portion 422 at 90 ° intervals in the circumferential direction. The recesses 423 formed in the pair of flange portions 422 are formed at positions where they overlap each other in the axial direction.

As shown in FIGS. 3 and 4, the recess 423 has a bottom surface 423a facing the inner peripheral side and a pair of side surface 423b connected to the bottom surface 423a and facing each other in the circumferential direction. In the present embodiment, the bottom surface 423a is formed up to the outer peripheral side from the central position of the flange portion 422 in the radial direction. That is, the length of the recess 423 in the radial direction has a length of more than half the length of the flange portion 422 in the radial direction. As shown in FIG. 3, the bottom surface 423a and the side surface 423b in the recess 423 are formed in a curved surface shape that smoothly connects the bottom surface 423a and the side surface 423b. In the present embodiment, the bottom surface 423a is formed in a convex arc shape on the outer peripheral side, and is smoothly connected between both ends of the bottom surface 423a and the side surface 423b so as not to form a corner.

The portion of the flange portion 422 between the circumferential portions of the concave portions 423 adjacent to each other in the circumferential direction is an opposed protruding portion 422a facing the end surface 431a of the annular portion 431. The facing protrusions 422a are formed in a part of the outer ring 42 in the circumferential direction, and are on the inner peripheral side of the outer ring 42 located on both sides of the facing protrusions 422a in the circumferential direction (that is, the bottom surface 423a of the recess 423). It stands out. Opposing protrusions 422a formed on both sides of the outer ring 42 in the axial direction position the cage 43 between them. The inner peripheral surfaces of the facing protrusions 422a are formed at the same radial positions on the entire circumference. Then, as shown in FIGS. 1 and 2, a flexspline 5 is externally fitted on the outer peripheral surface of the outer ring 42.

As shown in FIG. 2, the flexspline 5 has a cup shape with one side open in the axial direction, and has a bottom wall 51 and a cylindrical side wall 52 erected axially from the peripheral edge of the bottom wall 51. .. Although not shown, an output rotation shaft for taking out the output of the strain wave gearing 1 is attached to the bottom wall 51. That is, the strain wave gearing device 1 is configured to receive a rotation input from an input rotation shaft inserted in the elliptical cam 3 and output a decelerated rotation from the flexspline 5 via the output rotation shaft.

The open end of the flexspline 5 is fitted onto the needle roller bearing 4. The flexspline 5 is made of metal, and at least the side wall 52 of the flexspline 5 is formed thin enough to be elastically deformed in the radial direction. In a state where the flexspline 5 is fitted onto the needle roller bearing 4, the flexspline 5 is elastically deformed into an elliptical shape along the outer peripheral surface of the needle roller bearing 4. As a result, the outer peripheral surfaces of the flexspline 5, the outer ring 42, the inner ring 41, and the elliptical cam 3 are formed in an elliptical shape substantially parallel to each other. The flexspline 5 has external teeth 521 at a portion fitted with the needle roller bearing 4. An annular circular spline 6 is arranged on the outer peripheral side of the flexspline 5.

The circular spline 6 is formed by forming a highly rigid metal in an annular shape. The circular spline 6 has internal teeth 61 on its inner peripheral portion. The internal teeth 61 of the circular spline 6 are formed in a circumferential shape concentric with the rotation center of the input shaft inserted into the elliptical cam 3. The internal teeth 61 of the circular spline 6 and the external teeth 521 of the flexspline 5 mesh with each other at both ends of the long axis direction LD, but do not mesh with each other at both ends of the short axis direction SD. The number of internal teeth 61 of the circular spline 6 is two more than the number of external teeth 521 of the flexspline 5. As a result, each time the elliptical cam 3 rotates once, the flexspline 5 rotates by the difference in the number of teeth between the internal teeth 61 and the external teeth 521. As a result, the decelerated rotation is output from the flexspline 5. The difference in the number of teeth between the internal teeth 61 and the external teeth 521 can be appropriately changed according to the requirement for the reduction ratio.

(Actions and effects of the first embodiment)
In the needle roller bearing 4 for the strain wave gearing 1 of the present embodiment, the outer ring 42 has facing protrusions 422a facing each other of the end faces 431a of the pair of annular portions 431 at both ends in the axial direction. The facing protruding portion 422a is formed in a part of the outer ring 42 in the circumferential direction, and is formed so as to project toward the inner peripheral side of the outer ring 42 so as to protrude from the portions located on both sides of the facing protruding portion 422a in the circumferential direction. .. In this way, by projecting the facing protrusions 422a from the portions of the outer rings 42 formed at the positions on both sides in the circumferential direction, both sides of the facing protrusions 422a in the circumferential direction are spaces (recesses 423 in this embodiment). Will be. Therefore, even when the outer ring 42 that is repeatedly elastically deformed with the rotation of the elliptical cam 3 is provided with the facing protrusion 422a that protrudes toward the inner peripheral side, the facing protrusion 422a is likely to be elastically deformed and the outer ring 42 is cracked. It can be prevented.

Further, the outer ring 42 has a flange portion 422 protruding toward the inner peripheral side from the entire circumference of each of both ends in the axial direction on the outer ring rolling surface 421a. The flange portion 422 has recesses 423 formed from the inner peripheral end toward the outer peripheral side at a plurality of locations in the circumferential direction. A portion of the flange portion 422 between the concave portions 423 adjacent to each other in the circumferential direction constitutes the facing protrusion 422a. Thereby, for example, after forming the annular flange portion 422 facing the end surface 431a of the annular portion 431, the recesses 423 are formed by cutting out a plurality of points in the circumferential direction, so that the portions between the recesses 423 are opposed to each other. Since the portion 422a can be formed, it is easy to improve the productivity of the outer ring 42.

Further, the concave portion 423 is formed in a curved surface shape in which the bottom surface 423a and the side surface 423b smoothly connect the bottom surface 423a and the side surface 423b. Therefore, it is possible to reduce the stress concentration on the portion between the bottom surface 423a and the side surface 423b of the recess 423.

Further, the length of the recess 423 in the radial direction has a length of more than half the length of the flange portion 422 in the radial direction. Therefore, the facing protrusion 422a formed between the concave portions 423 in the circumferential direction is more likely to be elastically deformed, and the stress generated in the flange portion 422 is more likely to be reduced.

As described above, according to the present embodiment, it is possible to provide the roller bearing 4 for the wave gear device 1 that can prevent the outer ring 42 from cracking.

[Second Embodiment]
As shown in FIGS. 6 and 7, the present embodiment is a form in which the shape of the outer ring 42 is changed from that of the first embodiment. FIG. 6 is a front view of the strain wave gearing device 1 in the present embodiment, and FIG. 7 is an enlarged view of the periphery of the facing protrusion 422a of FIG.

In the present embodiment, the outer ring 42 has a tubular portion 421 and an opposed protruding portion 422a formed so as to project inward from a part of the circumferential direction at each of both ends of the tubular portion 421 in the axial direction. .. In this embodiment, facing protrusions 422a are formed at four points of the flange portion 422 at 90 ° intervals in the circumferential direction. The facing protrusions 422a formed on the pair of flanges 422 are formed at positions where they overlap each other in the axial direction. The facing protrusion 422a is a case where the facing protrusions 422a are present at both ends of the major axis LD of the outer ring 42 (that is, when the facing protrusions 422a are present at a portion where the cage 43 is closer to the inner peripheral side). Even if there is, at least a part of the facing protrusion 422a is formed so as to face the end surface 431a of the annular portion 431 of the cage 43 in the axial direction. Further, the root portion (outer peripheral end portion) of the facing protrusion 422a is formed so as to become wider toward the tubular portion 421 side (outer peripheral side).

Others are the same as those in the first embodiment.
In addition, among the codes used in the second and subsequent embodiments, the same codes as those used in the above-mentioned forms represent the same components and the like as those in the above-mentioned forms, unless otherwise specified.

(Actions and effects of the second embodiment)
In the present embodiment, the outer ring 42 has a tubular portion 421 and an opposed protruding portion 422a formed so as to project inward from a part of the circumferential direction at each of both ends of the tubular portion 421 in the axial direction. .. Therefore, even if the facing protrusion 422a is formed on the outer ring 42, the outer ring 42 is likely to be elastically deformed, and it is easy to prevent the outer ring 42 from being cracked.

Further, the facing protrusion 422a is formed so wide that the root portion thereof is directed toward the tubular portion 421. Therefore, the strength of the facing protrusion 422a can be ensured.
In addition, this embodiment also has the same effect as that of the first embodiment.

(Additional note)
Although the present invention has been described above based on the embodiments, the embodiments do not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

Further, the present invention can be appropriately modified and implemented by omitting a part of the configuration or adding or replacing the configuration within a range not deviating from the gist thereof.

For example, in each of the above-described embodiments, an example of a needle roller bearing is shown as the roller bearing, but other roller bearings such as a cylindrical roller bearing may be used.

Further, in each of the above-described embodiments, the roller bearing is provided with an inner ring, but it is also possible to adopt a configuration in which the inner ring is omitted. In this case, roller bearings are incorporated into the strain wave gearing so that the plurality of rollers are in direct contact with, for example, the outer peripheral surface of the elliptical cam.

1 ... Strain wave gearing 2 ... Wave generator 3 ... Elliptical cam 4 ... Needle roller bearing (roller bearing)
42 ... Outer ring 421 ... Cylindrical portion 421a ... Outer ring rolling surface 422 ... Flange portion 423 ... Recessed portion 423a ... Bottom surface 423b ... Side surface 422a ... Opposing protrusion 43 ... 433 ... Pocket 44 ... Needle roller 5 ... Flex spline 521 ... External tooth 6 ... Circular spline 61 ... Internal tooth

Claims (5)

A roller bearing for a strain wave gearing that is interposed between an elliptical cam and a flexspline having external teeth that mesh with the internal teeth of the circular spline at both ends in the longitudinal direction of the elliptical cam.
An elastically deformable outer ring fitted inside the flexspline,
A plurality of rollers arranged on the rolling surface of the outer ring and
The plurality of rollers have a pair of annular portions facing each other from both sides in the axial direction, and a plurality of pillar portions arranged at predetermined intervals in the circumferential direction between the pair of annular portions, and between the plurality of pillar portions. Equipped with a cage with pockets to hold multiple rollers so that they can roll freely.
The outer ring has opposed protrusions at both ends in the axial direction facing each other on the far-flung ends of the pair of annular portions.
The facing protrusions are formed in a part of the outer ring in the circumferential direction, and are formed so as to protrude inward from the portions located on both sides of the facing protrusions in the outer ring in the circumferential direction.
Roller bearings for strain wave gearing. The outer ring has a flange portion protruding toward the inner peripheral side from the entire circumference of each of both ends in the axial direction on the rolling surface.
The flange portion has recesses formed from the inner peripheral end toward the outer peripheral side at a plurality of locations in the circumferential direction.
A portion of the flange portion between the concave portions adjacent to each other in the circumferential direction constitutes the facing protrusion.
The roller bearing for the strain wave gearing according to claim 1. The recess is formed in a curved surface between the bottom surface and the side surface so as to smoothly connect the bottom surface and the side surface.
The roller bearing for the strain wave gearing according to claim 2. The length of the recess in the radial direction has a length of more than half the length of the flange portion in the radial direction.
The roller bearing for the strain wave gearing according to claim 2 or 3. The outer ring is formed so that the inner peripheral surface projects toward the inner peripheral side from a part of the circumferential direction at each of the cylindrical portion constituting the rolling surface and both ends of the tubular portion in the axial direction. With opposed protrusions,
The roller bearing for the strain wave gearing according to claim 1.

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