JP2021055767A

JP2021055767A - Ball bearing

Info

Publication number: JP2021055767A
Application number: JP2019179982A
Authority: JP
Inventors: 鈴木　康介; Kosuke Suzuki; 康介鈴木
Original assignee: NTN Corp; NTN Toyo Bearing Co Ltd
Current assignee: NTN Corp
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2021-04-08

Abstract

To provide a technology that further improves rated load of a ball bearing and is excellent in load performance for thrust load in both direction, and can be assembled to a wave gear reducer and the like.SOLUTION: A ball bearing 1 includes: an inner ring 5 and an outer ring 6; and multiple balls 9 interposed between the raceway grooves 7, 8 thereof opposed to each other. The inner ring 5 and the outer ring 6 have a circular shape in a state of nature and have elasticity capable of deforming into a non-circular shape. Only the inner ring 5 of the inner ring 5 and the outer ring 6 is provided with a filling groove 20 at a shoulder surface. The filling groove 20 has a groove bottom of which depth does not reach a groove bottom of the raceway groove 7 of the inner ring 5.SELECTED DRAWING: Figure 1

Description

この発明は、玉軸受に関し、特に波動歯車減速機等に組み込まれる玉軸受に関する。 The present invention relates to ball bearings, and more particularly to ball bearings incorporated in wave gear reducers and the like.

波動歯車減速機は、内歯を有する環状のサーキュラスプラインの径方向内側に、その内歯と噛み合う外歯を有する環状のフレクスプラインを配置すると共に、フレクスプラインの径方向内側に前記フレクスプラインを楕円形に撓ませるウェーブジェネレータを配し、サーキュラスプラインの角度を固定してウェーブジェネレータを回転させる。ウェーブジェネレータを回転させると、ウェーブジェネレータの１回転に対してフレクスプラインがサーキュラスプラインとの歯数差分だけ回転する。ウェーブジェネレータは、回転駆動される楕円形状のカムと、このカムの外周と前記フレクスプラインの内周との間に組み込まれる玉軸受とで構成されている。 The wave gear reducer arranges an annular flexspline having external teeth that mesh with the internal teeth inside the annular circular spline having internal teeth, and makes the flexspline elliptical inside the radial spline of the flexspline. Arrange a wave generator that bends into a shape, fix the angle of the circular spline, and rotate the wave generator. When the wave generator is rotated, the flexspline rotates by the difference in the number of teeth from the circular spline for one rotation of the wave generator. The wave generator is composed of a rotary-driven elliptical cam and a ball bearing incorporated between the outer circumference of the cam and the inner circumference of the flexspline.

この波動歯車減速機に用いられる玉軸受は、外輪および内輪が複数の玉を挟んでそれぞれ楕円形に変形した状態で組み込まれ、カムおよび内輪の回転に伴って玉に押された外輪が楕円形の姿勢を変化させるように変化していくことで、使用中の外輪の変形挙動を安定させて軸受寿命を延長するために、一般的な用途に用いられるものよりも多くの玉を組み込むことが求められる。 The ball bearing used in this strain wave gearing is incorporated in a state where the outer ring and the inner ring are deformed into an elliptical shape with a plurality of balls sandwiched between them, and the outer ring pushed by the balls as the cam and the inner ring rotate is elliptical. In order to stabilize the deformation behavior of the outer ring in use and extend the bearing life by changing the posture of the ball, it is possible to incorporate more balls than those used for general purposes. Desired.

玉軸受において、内外輪間に多くの玉を入れる技術としては、例えば、図１６に示すように、内輪１０５と外輪１０６の軌道溝１０７，１０８に隣接する肩部を貫通して、玉１０９を入れる入れ溝１２０を設けることが知られている。一般的な玉軸受では、内輪１０５および外輪１０６が弾性変形しない剛体と見做されるため、この剛体の内輪１０５と外輪１０６の間に玉１０９を導入可能なように、入れ溝１２０の深さは、軌道溝１０７，１０８の幅面の入口では軌道溝１０７，１０８よりも深く、次第に浅くなって最奥部で軌道溝１０７，１０８の深さに一致するように形成される。
しかし、このような大きな入れ溝１２０を設けると、両方向のスラスト力を受けることができないと言う問題点が生じる。 In a ball bearing, as a technique for inserting a large number of balls between the inner and outer rings, for example, as shown in FIG. 16, the balls 109 are inserted through the shoulder portions adjacent to the raceway grooves 107 and 108 of the inner ring 105 and the outer ring 106. It is known that the insertion groove 120 is provided. In a general ball bearing, the inner ring 105 and the outer ring 106 are considered to be rigid bodies that are not elastically deformed. Therefore, the depth of the groove 120 is such that the ball 109 can be introduced between the inner ring 105 and the outer ring 106 of the rigid body. Is deeper than the track grooves 107 and 108 at the entrance of the width surface of the track grooves 107 and 108, gradually becomes shallower, and is formed so as to match the depth of the track grooves 107 and 108 at the innermost part.
However, if such a large insertion groove 120 is provided, there arises a problem that the thrust force in both directions cannot be received.

このような課題を解消するものとして、波動歯車減速機に用いられる玉軸受の特徴である軌道輪の弾性変形性を利用して玉を入れるようにし、入れ溝を設けることなく、玉の充填率を２６％未満に規制することで、玉軸受の定格荷重を高め、かつ両方向のスラスト力受けることを可能にすることが提案されている（特許文献１）。 In order to solve such a problem, the ball is inserted by utilizing the elastic deformability of the raceway ring, which is a feature of the ball bearing used in the wave gear reducer, and the filling rate of the ball is not provided. It has been proposed that the rated load of ball bearings can be increased and the thrust force in both directions can be received by regulating the value to less than 26% (Patent Document 1).

特許第６５３６２７１号公報Japanese Patent No. 6536271

特許文献１に記載の発明は、玉軸受の定格荷重を高め、かつ両方向のスラスト力受けることを可能にする点で、波動歯車減速機用の玉軸受として優れている。しかし、入れ溝を設けることなく、軌道輪の弾性変形性のみで玉を入れる個数を増やそうとする技術であるため、玉軸受の定格荷重を、今一つ十分に大きくできず、さらに大きな定格荷重を受けることができるようにすることが望まれる。 The invention described in Patent Document 1 is excellent as a ball bearing for a wave gear reducer in that the rated load of the ball bearing can be increased and thrust force in both directions can be received. However, since it is a technology that attempts to increase the number of balls to be inserted only by the elastic deformability of the raceway ring without providing a groove, the rated load of the ball bearing cannot be increased sufficiently, and a larger rated load is received. It is hoped that it will be possible.

この発明は、上記課題を解消するものであり、玉軸受の定格荷重をより一層高め、かつ両方向のスラスト荷重の負担性能にも優れた技術を提供することである。 The present invention solves the above problems, and provides a technique for further increasing the rated load of ball bearings and also excellent in bearing performance of thrust load in both directions.

この発明の玉軸受は、内輪および外輪と、これら内輪および外輪の対向する軌道溝間に円周方向に並んで介在する複数の玉とを備え、
前記内輪および外輪は、自然状態で円形であって非円形に変形可能な弾性を有し、
前記内輪および外輪のうちの内輪のみに、前記軌道溝を除く外周面部分である肩面に、前記内輪の幅面から前記軌道溝に続いて、軸受外部から内外輪の前記軌道溝間に前記玉を入れる入れ溝が設けられ、
この入れ溝は、溝底が前記内輪の軌道溝の溝底に達しない深さとされている。 The ball bearing of the present invention includes an inner ring and an outer ring, and a plurality of balls interposed between the inner ring and the outer ring facing raceway grooves in a circumferential direction.
The inner ring and the outer ring have elasticity that is circular in a natural state and can be deformed into a non-circular shape.
Only on the inner ring of the inner ring and the outer ring, on the shoulder surface which is the outer peripheral surface portion excluding the raceway groove, from the width surface of the inner ring to the raceway groove, and between the bearing outer side and the raceway groove of the inner and outer rings, the ball. There is a groove to put in
The depth of the groove is such that the bottom of the groove does not reach the bottom of the raceway groove of the inner ring.

この構成によると、前記内輪および外輪は自然状態で円形であるが、非円形に変形可能な弾性を有し、かつ内輪に入れ溝を有する。このため、入れ溝を設けない場合に比べて、内外輪間に多くの玉を入れることができ、また玉数が同じである場合はより大径の玉を入れることができる。このように玉の個数を多くでき、または玉の径を大きくできるため、玉軸受の定格荷重、つまり負荷容量が増大し、軸受寿命が長くなる。また、玉の数を多くした場合は、カムの外周面の楕円形状をより正確に外輪に転写できる。
入れ溝を設けること自体は、負荷できるスラスト力の低下となるが、この発明で設ける入れ溝は、溝底が内輪の軌道溝の溝底に達しない深さとされて浅く、また内輪および外輪のうちの内輪のみに設けるため、入れ溝を設けることよるスラスト力の負荷容量の低減よりも、入れ溝を設けたことで玉数または玉径の増大が得られることによるスラスト力の負荷容量の増大の方が大きく、前記入れ溝を設けたことで、却って両方向のスラスト力の負荷容量が増大する。 According to this configuration, the inner ring and the outer ring are circular in a natural state, but have elasticity that can be deformed into a non-circular shape, and have a groove in the inner ring. Therefore, as compared with the case where the insertion groove is not provided, a large number of balls can be inserted between the inner and outer rings, and when the number of balls is the same, a larger diameter ball can be inserted. Since the number of balls can be increased or the diameter of the balls can be increased in this way, the rated load of the ball bearing, that is, the load capacity is increased, and the bearing life is extended. Further, when the number of balls is increased, the elliptical shape of the outer peripheral surface of the cam can be transferred to the outer ring more accurately.
Providing the insertion groove itself reduces the thrust force that can be loaded, but the insertion groove provided in the present invention is shallow because the groove bottom does not reach the groove bottom of the raceway groove of the inner ring, and the inner ring and the outer ring are provided. Since it is provided only on the inner ring of the inner ring, the load capacity of the thrust force is increased by increasing the number of balls or the diameter of the balls by providing the insertion groove, rather than reducing the load capacity of the thrust force by providing the insertion groove. Is larger, and the provision of the groove increases the load capacity of the thrust force in both directions.

特に、この玉軸受が波動歯車減速機に用いられる場合は、楕円状のカムの外周に嵌められることによって楕円状に変形させられるが、その楕円形状の短軸位置ではサーキュラスプラインからフレクスプラインが径方向に離れていて、スラスト力の作用を受け難い。そのため、楕円形状の短軸位置に前記入れ溝が位置するように内輪を楕円状のカムに嵌合させると、入れ溝を設けたことによるスラスト力負荷の低下がより一層少なくなり、軸受全体としてのスラスト力の負荷容量がより一層増大する。 In particular, when this ball bearing is used in a wave gear reducer, it is deformed into an elliptical shape by being fitted on the outer circumference of an elliptical cam, but at the short axis position of the elliptical shape, the diameter of the flex thrust line is from the circular thrust line. It is far away in the direction and is not easily affected by thrust force. Therefore, when the inner ring is fitted to the elliptical cam so that the groove is located at the position of the short axis of the ellipse, the decrease in the thrust force load due to the provision of the groove is further reduced, and the bearing as a whole is reduced. The load capacity of the thrust force of is further increased.

前記入れ溝は、断面形状が円弧状であってもよい。
入れ溝の断面形状が円弧状であると、玉の断面形状に近い形状とできて、入れ溝の開口幅を狭くでき、入れ溝を設けたことによるスラスト力の負荷容量の低減がより抑ええられる。 The groove may have an arcuate cross-sectional shape.
If the cross-sectional shape of the grooving is arcuate, the shape can be close to the cross-sectional shape of the ball, the opening width of the grooving can be narrowed, and the reduction of the thrust load capacity due to the grooving can be further suppressed. Be done.

前記入れ溝は、断面形状が、前記内輪の軸心と平行な平面、または前記玉の曲率半径に対して平面と見做せる程度に十分に大きな曲率半径の円弧状であってもよい。
内輪の肩面を軸心と平行な平面で切り落とした形状、いわゆるＤカット形状とすると、その切り落とし範囲の中心部が軌道溝の溝底面に最も近づく溝となる。このような断面形状が平面の入れ溝とすることで、円弧溝形状とする場合に比べて、負荷が作用した場合の応力集中が生じ難くなる。
前記平面の入れ溝とする場合、平面加工のための工具の種類が限られるが、曲率半径の大きな回転砥石を用いた場合、完全な平面とはならないが、疑似的な平面、つまり平面と見做せる程度に十分に大きな曲率半径の円弧状の入れ溝が形成できる。このような疑似的な平面の入れ溝であっても、前記平面の入れ溝と同様な応力集中回避の作用が得られ、かつ加工が簡単に行える。 The groove may be a plane whose cross-sectional shape is parallel to the axis of the inner ring, or an arc shape having a radius of curvature sufficiently large so that it can be regarded as a plane with respect to the radius of curvature of the ball.
If the shoulder surface of the inner ring is cut off in a plane parallel to the axis, that is, a so-called D-cut shape, the central portion of the cut-off range is the groove closest to the bottom surface of the raceway groove. When such a cross-sectional shape is a flat groove, stress concentration is less likely to occur when a load is applied, as compared with the case where the arc groove shape is used.
When the groove is used for a flat surface, the types of tools for flat surface processing are limited, but when a rotary grindstone with a large radius of curvature is used, it is not a perfect flat surface, but it is regarded as a pseudo flat surface, that is, a flat surface. An arcuate groove with a radius of curvature sufficiently large can be formed. Even with such a pseudo-planar grooving, the same stress concentration avoidance effect as that of the flat grooving can be obtained, and processing can be easily performed.

前記入れ溝の深さは、前記内輪の前記軌道溝に深さに対して１０％〜８０％の範囲であってもよい。
前記入れ溝の深さは、深くなるに従い、玉を入れ易くなって玉数・玉径の増大効果が大きくなるが、スラスト力の負荷容量の低減作用が大きくなる。これとは逆に、浅くなるに従い、玉を入れ難くなり、玉数・玉径の増大効果が小さくなるが、スラスト力の負荷容量の低減程度が小さくなる。入れ溝の深さが前記１０％〜８０％の範囲であれば、玉を入れ易くて玉数・玉径の増大効果が確保され、かつスラスト力の負荷容量の低減程度が小さく、総合的に、入れ溝を設けながら、スラスト力の負荷容量が増大する。 The depth of the insertion groove may be in the range of 10% to 80% with respect to the depth of the raceway groove of the inner ring.
As the depth of the insertion groove becomes deeper, it becomes easier to insert balls and the effect of increasing the number of balls and the diameter of the balls increases, but the effect of reducing the load capacity of the thrust force increases. On the contrary, as it becomes shallower, it becomes more difficult to insert balls, and the effect of increasing the number of balls and the diameter of balls becomes smaller, but the degree of reduction in the load capacity of the thrust force becomes smaller. When the depth of the insertion groove is in the range of 10% to 80%, it is easy to insert balls, the effect of increasing the number of balls and the diameter of the balls is secured, and the degree of reduction of the load capacity of the thrust force is small, and overall. , The load capacity of the thrust force increases while providing the groove.

前記玉軸受は、例えば深溝玉軸受とされる。深溝玉軸受は、ラジアル軸受であるが、両方向のスラスト力をある程度負担でき、波動歯車減速機の玉軸受等として好ましい。このような深溝玉軸受の場合に、この発明における前記の軌道溝の溝底に達しない深さの入れ溝等を設けることで、この発明における、定格荷重をより一層高め、かつ両方向のスラスト荷重の負担性能にも優れると言う効果が、効果的に発揮される。 The ball bearing is, for example, a deep groove ball bearing. Although the deep groove ball bearing is a radial bearing, it can bear thrust force in both directions to some extent and is preferable as a ball bearing of a strain wave gearing speed reducer. In the case of such a deep groove ball bearing, the rated load in the present invention can be further increased and the thrust load in both directions can be further increased by providing a groove having a depth that does not reach the groove bottom of the raceway groove in the present invention. The effect of being excellent in bearing performance is effectively exhibited.

この発明の玉軸受は、波動歯車減速機に備わる楕円状のカムの外周に前記内輪が嵌合し、フレクスプラインの内周に前記外輪が嵌合し、前記カムの楕円形状の短軸の位置付近に前記入れ溝が位置するように用いられる軸受であってもよい。
前述のように、この玉軸受が波動歯車減速機に用いられる場合は、楕円状のカムの外周に嵌められることによって楕円に変形させられるが、その楕円形状の短軸位置ではサーキュラスプラインからフレクスプラインが径方向に離れていて、スラスト力の作用を受け難い。そのため、楕円形状の短軸位置に前記入れ溝が位置するように玉軸受の内輪を楕円状のカムに嵌合させると、入れ溝を設けたことによるスラスト力の負荷容量の低下がより一層少なくなり、軸受全体としてのスラスト力の負荷容量がより一層増大する。 In the ball bearing of the present invention, the inner ring is fitted on the outer circumference of the elliptical cam provided in the wave gear speed reducer, the outer ring is fitted on the inner circumference of the flexspline, and the position of the elliptical short axis of the cam is provided. The bearing may be used so that the groove is located in the vicinity.
As mentioned above, when this ball bearing is used in a wave gear reducer, it is deformed into an ellipse by being fitted on the outer circumference of an elliptical cam, but at the short axis position of the ellipse, the circular thrust line to the flex spline. Are separated in the radial direction and are not easily affected by thrust force. Therefore, when the inner ring of the ball bearing is fitted to the elliptical cam so that the groove is located at the position of the short axis of the elliptical shape, the reduction in the load capacity of the thrust force due to the provision of the groove is further reduced. Therefore, the load capacity of the thrust force of the bearing as a whole is further increased.

この発明の玉軸受の組み立て方法は、この発明の前記いずれかの構成の玉軸受を組み立てる方法であって、
前記複数の玉を前記内輪の軌道溝と外輪の軌道溝との間に組み込むときに、
まず、前記複数の玉のうち２つのみを支点用として、前記内輪の軌道溝と外輪の軌道溝との間に所定の角度間隔をおいて配置し、このとき、前記内輪の前記入れ溝は前記所定の角度間隔の範囲から外れ、かつ前記所定の角度間隔の中央から９０°離れた箇所までの範囲に入る位置とし、
前記内輪および外輪に、前記両支点用玉の角度間隔の中央位置付近で、前記内輪と外輪間の径方向隙間を狭める方向の荷重を加えて、前記内輪および外輪を弾性変形させ、
前記複数の玉のうち、前記支点用玉以外の玉を前記入れ溝から、前記内輪の軌道溝と外輪の同溝との間に入れていく。 The ball bearing assembly method of the present invention is a method of assembling a ball bearing having any of the above-described configurations of the present invention.
When incorporating the plurality of balls between the raceway groove of the inner ring and the raceway groove of the outer ring,
First, only two of the plurality of balls are used as fulcrums, and are arranged at a predetermined angular interval between the raceway groove of the inner ring and the raceway groove of the outer ring. A position that deviates from the range of the predetermined angle interval and enters a range 90 ° away from the center of the predetermined angle interval.
A load is applied to the inner ring and the outer ring in the direction of narrowing the radial gap between the inner ring and the outer ring near the central position of the angular distance between the two fulcrum balls to elastically deform the inner ring and the outer ring.
Among the plurality of balls, balls other than the fulcrum balls are inserted from the insertion groove between the raceway groove of the inner ring and the same groove of the outer ring.

この組み立て方法によれば、内輪と外輪の間の所定位置に２つの支点用玉を配置して、両支点用玉の間で内輪および外輪に荷重を加えるだけで、各支点用玉間の位置に対して周方向で荷重が加えられる側と反対側とに、それぞれ内輪と外輪の径方向隙間が広がる領域が形成される。その箇所のうちのいずれかの箇所に前記入れ溝が位置するようにしておいて、内輪と外輪との間に残りの玉を組み込むことができる。そのため、通常の深溝玉軸受の組み立て方法よりも玉の充填率を高めることができる。したがって、前記入れ溝をより浅くしても玉の充填率を高めることができる。 According to this assembly method, two fulcrum balls are placed at predetermined positions between the inner ring and the outer ring, and a load is applied to the inner ring and the outer ring between the two fulcrum balls, and the position between the fulcrum balls is obtained. On the side opposite to the side where the load is applied in the circumferential direction, a region is formed in which the radial gap between the inner ring and the outer ring widens, respectively. The insertion groove can be located at any of the portions, and the remaining balls can be incorporated between the inner ring and the outer ring. Therefore, the ball filling rate can be increased as compared with the usual method for assembling deep groove ball bearings. Therefore, the ball filling rate can be increased even if the insertion groove is made shallower.

この発明の玉軸受付きカムは、外周面が楕円状のカムと、このカムの前記外周面に内輪の内周面が嵌合する玉軸受とでなり、前記カムの前記楕円形状の短軸の付近となる周方向位置に前記入れ溝が位置する。前記玉軸受は、この発明の前記いずれかの構成の玉軸受である。
この構成であると、この発明の玉軸受につき説明したように、玉軸受の定格荷重をより一層高め、かつ両方向のスラスト荷重の負担性能にも優れる。また、前記カムの前記楕円形状の短軸の付近となる周方向位置に前記入れ溝が位置することにより、前記玉軸受の定格荷重がさらに高められ、かつ両方向のスラスト荷重の負担性能もさらに向上する。 The cam with a ball bearing of the present invention comprises a cam having an elliptical outer peripheral surface and a ball bearing in which the inner peripheral surface of the inner ring is fitted to the outer peripheral surface of the cam, and has a short axis of the elliptical shape of the cam. The groove is located in the vicinity of the circumferential position. The ball bearing is a ball bearing having any of the above configurations of the present invention.
With this configuration, as described for the ball bearing of the present invention, the rated load of the ball bearing is further increased, and the thrust load bearing performance in both directions is also excellent. Further, by locating the groove in the circumferential direction near the elliptical short axis of the cam, the rated load of the ball bearing is further increased, and the load performance of the thrust load in both directions is further improved. To do.

この発明の波動減速機は、内歯を有するサーキュラスプラインと、このサーキュラスプラインの前記内歯に噛み合う外歯を有するフレクスプラインと、外周面が楕円状のカム、およびこのカムの外周面に内輪の内周面が嵌合し外輪の外周面が前記フレクスプラインの内周面に嵌合する玉軸受を有する玉軸受付きカムとを備え、前記玉軸受がこの発明の前記いずれかの構成の玉軸受であって前記カムの前記楕円形状の短軸の付近となる周方向位置に前記入れ溝が位置する。
この構成の波動歯車減速機によると、この発明の玉軸受につき説明したように、玉軸受の定格荷重がより一層高められ、かつ両方向のスラスト荷重の負担性能にも優れる。 The wave reducer of the present invention has a circular spline having internal teeth, a flexspline having external teeth that mesh with the internal teeth of the circular spline, a cam having an elliptical outer peripheral surface, and an inner ring on the outer peripheral surface of the cam. A cam with a ball bearing having a ball bearing whose inner peripheral surface is fitted and the outer peripheral surface of the outer ring is fitted to the inner peripheral surface of the flexspline is provided, and the ball bearing is a ball bearing having any of the above configurations of the present invention. The groove is located at a circumferential position near the elliptical minor axis of the cam.
According to the strain wave gearing reducer having this configuration, as described for the ball bearing of the present invention, the rated load of the ball bearing is further increased, and the thrust load bearing performance in both directions is also excellent.

この発明の玉軸受は、内輪および外輪と、これら内輪および外輪の対向する軌道溝間に円周方向に並んで介在する複数の玉とを備え、前記内輪および外輪は、自然状態で円形であって非円形に変形可能な弾性を有し、前記内輪および外輪のうちの内輪のみに、前記軌道溝を除く外周面部分である肩面に、前記内輪の幅面から前記軌道溝に続いて、軸受外部から内外輪の前記軌道溝間に前記玉を入れる入れ溝が設けられ、この入れ溝は、溝底が前記内輪の軌道溝の溝底に達しない深さとされるため、玉軸受の定格荷重がより一層高められ、かつ両方向のスラスト荷重の負担性能にも優れる。 The ball bearing of the present invention includes an inner ring and an outer ring, and a plurality of balls interposed between the inner ring and the outer ring facing raceway grooves in a circumferential direction, and the inner ring and the outer ring are naturally circular. It has elasticity that can be deformed into a non-circular shape, and only the inner ring of the inner ring and the outer ring has bearings on the shoulder surface, which is the outer peripheral surface portion excluding the raceway groove, from the width surface of the inner ring to the raceway groove. A slot for inserting the ball is provided between the raceway grooves of the inner and outer rings from the outside, and the groove bottom is set to a depth that does not reach the groove bottom of the raceway groove of the inner ring, so that the rated load of the ball bearing is reached. Is further enhanced, and it is also excellent in bearing performance of thrust load in both directions.

この発明の玉軸受の組み立て方法は、この発明の前記いずれかの構成の玉軸受を組み立てる方法であって、前記複数の玉を前記内輪の軌道溝と外輪の軌道溝との間に組み込むときに、まず、前記複数の玉のうち２つのみを支点用として、前記内輪の軌道溝と外輪の軌道溝との間に所定の角度間隔をおいて配置し、このとき、前記内輪の前記入れ溝は前記所定の角度間隔の範囲から外れ、かつ前記所定の角度間隔の中央から９０°離れた箇所までの範囲に入る位置とし、前記内輪および外輪に、前記両支点用玉の角度間隔の中央位置付近で、前記内輪と外輪間の径方向隙間を狭める方向の荷重を加えて、前記内輪および外輪を弾性変形させ、前記複数の玉のうち、前記支点用玉以外の玉を前記入れ溝から、前記内輪の軌道溝と外輪の同溝との間に入れていくため、この発明の玉軸受の特長がより効果的に発揮されて、玉軸受の定格荷重がより一層高められ、かつ両方向のスラスト荷重の負担性能にも優れる。 The method for assembling a ball bearing of the present invention is a method of assembling a ball bearing having any of the above configurations of the present invention, and when the plurality of balls are incorporated between the raceway grooves of the inner ring and the raceway grooves of the outer ring. First, only two of the plurality of balls are used as fulcrums, and are arranged at a predetermined angular distance between the raceway groove of the inner ring and the raceway groove of the outer ring. Is a position that deviates from the range of the predetermined angular distance and enters a range 90 ° away from the center of the predetermined angular distance, and is located on the inner ring and the outer ring at the center position of the angular distance between the two fulcrum balls. In the vicinity, a load in the direction of narrowing the radial gap between the inner ring and the outer ring is applied to elastically deform the inner ring and the outer ring, and among the plurality of balls, balls other than the fulcrum balls are removed from the insertion groove. Since the ball bearing is inserted between the raceway groove of the inner ring and the same groove of the outer ring, the features of the ball bearing of the present invention are more effectively exhibited, the rated load of the ball bearing is further increased, and thrust in both directions is achieved. It also has excellent load bearing performance.

この発明の玉軸受付きカムおよび波動歯車減速機は、いずれも、この発明の玉軸受を用いるため、玉軸受の定格荷重がより一層高められ、かつ両方向のスラスト荷重の負担性能にも優れる。 Since the cam with ball bearings and the wave gear reducer of the present invention both use the ball bearings of the present invention, the rated load of the ball bearings is further increased, and the thrust load bearing performance in both directions is also excellent.

この発明の一実施形態に係る玉軸受を有する玉軸受付きカムを備えた波動歯車減速機を概念的に示す断面図である。It is sectional drawing which conceptually shows the wave gear speed reducer provided with the cam with a ball bearing which has the ball bearing which concerns on one Embodiment of this invention. 同波動歯車減速機を概念的に示す破断正面図である。It is a breaking front view which conceptually shows the same strain wave gearing reducer. 同玉軸受における内輪の斜視図である。It is a perspective view of the inner ring in the same ball bearing. 同内輪の側面図である。It is a side view of the inner ring. 同玉軸受の入れ溝の形成部分における内輪の断面と玉を示す拡大断面図である。It is an enlarged cross-sectional view which shows the cross section of the inner ring and the ball in the part where the insertion groove of the ball bearing is formed. 同内輪の入れ溝の形成部分を示す部分拡大正面図である。It is a partially enlarged front view which shows the formation part of the insertion groove of the inner ring. 同玉軸受の内輪の変形例における入れ溝の形成部分での内輪の断面と玉を示す拡大断面図である。It is an enlarged sectional view which shows the cross section of the inner ring and the ball at the part where the groove is formed in the modification of the inner ring of the ball bearing. 同内輪の入れ溝の形成部分を示す部分拡大正面図である。It is a partially enlarged front view which shows the formation part of the insertion groove of the inner ring. 同内輪の他の変形例における入れ溝の形成部分を示す部分拡大正面図である。It is a partially enlarged front view which shows the formation part of the insertion groove in another modification of the inner ring. 外輪の変形量と外輪内径に発生する引っ張り応力の関係例を示すグラフである。It is a graph which shows the relation example of the deformation amount of the outer ring, and the tensile stress generated in the inner diameter of an outer ring. 同玉軸受の組み立て方法の最初の手順を示す正面図である。It is a front view which shows the first procedure of the assembling method of a ball bearing. 図１１に続く組み立て方法の手順を説明する正面図である。It is a front view explaining the procedure of the assembling method following FIG. 実施形態の組み立て方法で組み立てられた玉軸受の玉の充填率を示す正面図である。It is a front view which shows the filling rate of the ball of the ball bearing assembled by the assembly method of embodiment. 通常の深溝玉軸受の組み立て方法を示す正面図である。It is a front view which shows the assembly method of a normal deep groove ball bearing. 図１２の状態の外輪と内輪の径方向隙間を示すグラフである。It is a graph which shows the radial gap between the outer ring and the inner ring in the state of FIG. 従来の玉軸受における入れ溝の形成部分を示す断面図である。It is sectional drawing which shows the formation part of the groove in the conventional ball bearing.

この発明の一実施形態を図面と共に説明する。図１、２に示すように、この玉軸受１は波動歯車減速機用のものである。この波動歯車減速機は、サーキュラスプライン２と、フレクスプライン３と、カム４と、前記フレクスプライン３とカム４との間に介在する玉軸受１とを備える。 An embodiment of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the ball bearing 1 is for a strain wave gearing speed reducer. This strain wave gearing speed reducer includes a circular spline 2, a flexspline 3, a cam 4, and a ball bearing 1 interposed between the flexspline 3 and the cam 4.

なお、この明細書において、「軸方向」は、玉軸受１の軸受中心線（図示せず）に沿った方向を言う。また、「径方向」は、前記「軸方向」を成す直線に対して直角な方向を言う。 In this specification, the "axial direction" refers to a direction along the bearing center line (not shown) of the ball bearing 1. Further, the "diameter direction" refers to a direction perpendicular to the straight line forming the "axial direction".

サーキュラスプライン２は、周方向に並ぶ所定数の内歯１が内周に設けられている。
フレクスプライン３は、フレキシブルな材質、例えば弾性変形可能な鋼材等の材質のリング状であり、サーキュラスプライン２の内歯１１に噛み合う外歯１５を外周に有する。フレクスプライン３の外歯１５の数は、サーキュラスプライン２の内歯１１の数よりも、若干数、例えば２つ少ない。一つ少なくしてもよい。フレクスプライン３は、この実施形態では、筒部１２と、この筒部１２の軸方向一端に連続する底部１３とで形成されたカップ状になっている。筒部１２の軸方向の先端は、フレクスプライン３の開口縁１４になっている。 The circular spline 2 is provided with a predetermined number of internal teeth 1 arranged in the circumferential direction on the inner circumference.
The flexspline 3 has a ring shape made of a flexible material, for example, an elastically deformable steel material, and has external teeth 15 that mesh with the internal teeth 11 of the circular spline 2 on the outer circumference. The number of external teeth 15 of the flexspline 3 is slightly less than the number of internal teeth 11 of the circular spline 2, for example two. You may reduce it by one. In this embodiment, the flexspline 3 has a cup shape formed by a tubular portion 12 and a bottom portion 13 continuous with one end of the tubular portion 12 in the axial direction. The axial tip of the tubular portion 12 is the opening edge 14 of the flexspline 3.

前記カム４は、楕円状に形成された外周面４ａを有し、任意の軸方向位置で同一の断面形状である。カム４は、中心部に第一軸Ｓ１が嵌合状態に固定され、第一軸Ｓ１と一体に回転する。フレクスプライン３は、第一軸Ｓ１と同軸心に配置された第二軸Ｓ２が底部１３の中心に嵌合状態に固定され、第二軸Ｓ２と一体に回転可能である。 The cam 4 has an elliptical outer peripheral surface 4a and has the same cross-sectional shape at an arbitrary axial position. The first shaft S1 is fixed to the center of the cam 4 in a fitted state, and the cam 4 rotates integrally with the first shaft S1. In the flexspline 3, the second axis S2 arranged coaxially with the first axis S1 is fixed to the center of the bottom portion 13 in a fitted state, and can rotate integrally with the second axis S2.

玉軸受１は、内輪５と外輪６と、内輪５の軌道溝７と外輪６の軌道溝８との端に周方向に並んで介在する一列の複数の玉９と、これらの玉９の周方向の間隔を保つ保持器１０とを備える。玉９の個数は、奇数個であっても偶数個であってもよいが、奇数個とされる場合が多い。保持器１０は、環状部分とその周方向複数箇所から軸方向に延びる柱部とでなる、いわゆる櫛形とされている。 The ball bearing 1 includes a plurality of balls 9 in a row interposed at the ends of the inner ring 5 and the outer ring 6, the raceway groove 7 of the inner ring 5 and the raceway groove 8 of the outer ring 6 in the circumferential direction, and the circumferences of the balls 9. It is provided with a cage 10 that keeps the distance between the directions. The number of balls 9 may be an odd number or an even number, but is often an odd number. The cage 10 has a so-called comb shape, which is composed of an annular portion and a pillar portion extending in the axial direction from a plurality of locations in the circumferential direction thereof.

玉軸受１は、例えば深溝玉軸受とされる。また、玉軸受１は、内輪肉厚ｔ１および外輪肉厚ｔ２が、ピッチ円直径ＰＣＤの割合にして、一般の深溝玉軸受に比べて薄い薄肉玉軸受とされている。 The ball bearing 1 is, for example, a deep groove ball bearing. Further, the ball bearing 1 is a thin ball bearing in which the inner ring wall thickness t1 and the outer ring wall thickness t2 are thinner than those of a general deep groove ball bearing in terms of the ratio of the pitch circle diameter PCD.

玉軸受１の内輪５および外輪６のうちの内輪５のみに、軌道溝７を除く外周面部分である肩面１７（図５参照）に、内輪５の幅面５ｂから軌道溝７に続いて、軸受外部から内外輪５，６の軌道溝７，８間に玉９を入れる入れ溝２０が設けられている。入れ溝２０は、円周方向の１箇所とされ、図３〜６の例では、軌道溝７に対する両側の肩面１７，１７に、互いに円周方向の同一の位置で設けられている。入れ溝２０は、図８の例のように、軌道溝７に対する片側の肩面１７のみに設けてもよい。また、入れ溝２０は円周方向の２箇所に設けてもよい。 Only on the inner ring 5 of the inner ring 5 and the outer ring 6 of the ball bearing 1, on the shoulder surface 17 (see FIG. 5) which is the outer peripheral surface portion excluding the raceway groove 7, from the width surface 5b of the inner ring 5 to the raceway groove 7. An insertion groove 20 for inserting a ball 9 is provided between the raceway grooves 7 and 8 of the inner and outer rings 5 and 6 from the outside of the bearing. The insertion groove 20 is provided at one position in the circumferential direction, and in the examples of FIGS. 3 to 6, the insertion grooves 20 are provided on the shoulder surfaces 17 and 17 on both sides of the track groove 7 at the same positions in the circumferential direction. The insertion groove 20 may be provided only on the shoulder surface 17 on one side with respect to the track groove 7, as in the example of FIG. Further, the insertion grooves 20 may be provided at two locations in the circumferential direction.

入れ溝２０は、溝底が内輪５の軌道溝７の溝底に達しない深さとされる。入れ溝２０の深さｈは、例えば、軌道溝７の溝深さＨの１０〜８０％と範囲とされ、より好ましくは２０〜７０％の範囲とされる。 The depth of the insertion groove 20 is such that the groove bottom does not reach the groove bottom of the raceway groove 7 of the inner ring 5. The depth h of the insertion groove 20 is, for example, in the range of 10 to 80% of the groove depth H of the track groove 7, and more preferably in the range of 20 to 70%.

入れ溝２０の断面形状は、図６に一例を示すように、例えば円弧状とされる。その円弧の曲率半径は、例えば玉９の半径と同じかこの半径よりも若干大きな径とされる。
入れ溝２０の断面形状は、図８に示すように、内輪６の軸心と平行な平面、いわゆるＤカット形状であってもよい。この他に、図９に示すように、入れ溝２０の断面形状は、玉９の曲率半径に対して平面と見做せる程度に十分に大きな曲率半径の円弧状、換言すれば疑似的な平面状であってもよい。この平面と見做せる程度に十分に大きな曲率半径の円弧状は、例えば、回転中心を内輪５の軸心方向に沿わせた大径の回転砥石で研磨することで得られる。 The cross-sectional shape of the insertion groove 20 is, for example, an arc shape as shown in FIG. 6 as an example. The radius of curvature of the arc is, for example, the same as or slightly larger than the radius of the ball 9.
As shown in FIG. 8, the cross-sectional shape of the insertion groove 20 may be a plane parallel to the axis of the inner ring 6, a so-called D-cut shape. In addition, as shown in FIG. 9, the cross-sectional shape of the groove 20 is an arc shape having a radius of curvature sufficiently large enough to be regarded as a plane with respect to the radius of curvature of the ball 9, in other words, a pseudo plane. It may be in the shape. An arc shape having a radius of curvature sufficiently large enough to be regarded as a flat surface can be obtained, for example, by polishing with a large-diameter rotary grindstone whose center of rotation is along the axial direction of the inner ring 5.

玉軸受１の内輪５および外輪６は、自然状態で円形であって、弾性を有する材質とされる。この弾性の程度は、入れ溝２０から玉９を入れるときに弾性域内で非円形に変形可能で、かつ玉軸受１を内輪５で楕円状のカム４の外周面４ａに嵌合させるときに弾性域内での変形となる範囲の弾性を持つ程度とされる。
内輪５および外輪６の材質は、例えば軸受鋼とされる。この軸受鋼は、炭素０．９％以上で１．１％以下、クロム０．９％以上で１．６％以下を含有する高炭素クロム鋼とである。この軸受鋼としては、例えば、ＪＩＳ規格（Ｇ４８０５：２００８）で規定された高炭素クロム鋼材が挙げられる。 The inner ring 5 and the outer ring 6 of the ball bearing 1 are made of an elastic material that is circular in a natural state. The degree of elasticity is such that the ball bearing 1 can be deformed non-circularly within the elastic region when the ball 9 is inserted from the groove 20, and the ball bearing 1 is elastic when the inner ring 5 is fitted to the outer peripheral surface 4a of the elliptical cam 4. It is said to have elasticity within the range of deformation within the region.
The material of the inner ring 5 and the outer ring 6 is, for example, bearing steel. This bearing steel is a high carbon chromium steel containing 0.9% or more of carbon and 1.1% or less, and 0.9% or more of chromium and 1.6% or less. Examples of this bearing steel include high carbon chromium steel materials specified in JIS standard (G4805: 2008).

図１、図２に示すように、玉軸受１の内輪５は、その内径面５ａにおいてカム４の外周面４ａに嵌合されることにより、楕円状に弾性変形させられる。この嵌合により、玉軸受１がカム４の外周面４ａに固定される。また、この際の内輪５の楕円状変形に伴い、外輪６が、玉９を介して押されることにより、楕円状に弾性変形させられる。この状態で、玉軸受１の外輪６の外径面６ａがフレクスプライン３の筒部１２の内側に圧入されることにより、フレクスプライン３の筒部１２も楕円状に変形させられる。 As shown in FIGS. 1 and 2, the inner ring 5 of the ball bearing 1 is elastically deformed into an elliptical shape by being fitted to the outer peripheral surface 4a of the cam 4 on its inner diameter surface 5a. By this fitting, the ball bearing 1 is fixed to the outer peripheral surface 4a of the cam 4. Further, with the elliptical deformation of the inner ring 5 at this time, the outer ring 6 is elastically deformed into an elliptical shape by being pushed through the ball 9. In this state, the outer diameter surface 6a of the outer ring 6 of the ball bearing 1 is press-fitted into the tubular portion 12 of the flexspline 3, so that the tubular portion 12 of the flexspline 3 is also deformed into an elliptical shape.

嵌合されたカム４と玉軸受１は、玉軸受付きのカム１６を構成し、この玉軸受付きのカム１６がウェーブジェネレータとなる。すなわち、第一軸Ｓ１が回転し、その第一軸Ｓ１に固定されているカム４の回転と一体に楕円状の玉軸受１が回転すると、この回転方向へ楕円形状の長軸の方向が変わり、サーキュラスプライン２の歯１１とフレクスプライン３の歯１５の噛み合う位置が回転方向に移動して、フレクスプライン３とサーキュラスプライン２との間に、１周で両者２，３の歯数差（この例では２個）分の相対回転が発生する。その相対回転が減速回転として取り出される。
この使用中、フレクスプライン３の弾性変形により、ウェーブジェネレータにスラスト力Ｆ（図１参照）が働く。このスラスト力Ｆは、玉軸受１の外輪６とフレクスプライン３との接触部（前記楕円形状の長軸上）からウェーブジェネレータに作用する。このため、ウェーブジェネレータを構成する玉軸受１は、スラスト力Ｆが負荷されることになる。 The fitted cam 4 and the ball bearing 1 form a cam 16 with a ball bearing, and the cam 16 with the ball bearing serves as a wave generator. That is, when the first axis S1 rotates and the elliptical ball bearing 1 rotates integrally with the rotation of the cam 4 fixed to the first axis S1, the direction of the elliptical long axis changes in this rotation direction. , The meshing position of the tooth 11 of the circular spline 2 and the tooth 15 of the flexspline 3 moves in the rotation direction, and the difference in the number of teeth between the flexspline 3 and the circular spline 2 in one round is 2 or 3 (this). In the example, 2) relative rotations occur. The relative rotation is taken out as a deceleration rotation.
During this use, a thrust force F (see FIG. 1) acts on the wave generator due to the elastic deformation of the flexspline 3. This thrust force F acts on the wave generator from the contact portion (on the long axis of the elliptical shape) between the outer ring 6 of the ball bearing 1 and the flexspline 3. Therefore, the thrust force F is applied to the ball bearing 1 constituting the wave generator.

この構成によると、内輪５および外輪６は自然状態で円形であるが、入れ溝２０から玉９を入れるときに弾性域内で非円形に変形可能な弾性を有し、かつ内輪５に入れ溝２０が設けられている。このため、入れ溝２０を設けない場合に比べて、内外輪５，６間に多くの玉９を入れることができ、また玉数が同じである場合はより大径の玉９を入れることができる。このように玉９の個数を多くでき、または玉９の径を大きくできるため、玉軸受１の定格荷重、つまり負荷容量が増大し、軸受寿命が長くなる。玉９の数を多くした場合は、楕円のカム４の形状をより正確に外輪６に転写できて、フレクスプライン３の外周の形状が、より正確にカム４の外周面４ａの形状に倣うことになる。これにより、サーキュラスプライン２とフレクスプライン３との噛み合いが円滑になる。 According to this configuration, the inner ring 5 and the outer ring 6 are circular in a natural state, but have elasticity that can be deformed into a non-circular shape within the elastic region when the ball 9 is inserted from the insertion groove 20, and the insertion groove 20 is inserted into the inner ring 5. Is provided. Therefore, as compared with the case where the insertion groove 20 is not provided, more balls 9 can be inserted between the inner and outer rings 5 and 6, and when the number of balls is the same, a larger diameter ball 9 can be inserted. it can. Since the number of balls 9 can be increased or the diameter of the balls 9 can be increased in this way, the rated load of the ball bearing 1, that is, the load capacity is increased, and the bearing life is extended. When the number of balls 9 is increased, the shape of the elliptical cam 4 can be transferred to the outer ring 6 more accurately, and the shape of the outer circumference of the flexspline 3 more accurately follows the shape of the outer peripheral surface 4a of the cam 4. become. As a result, the engagement between the circular spline 2 and the flex spline 3 becomes smooth.

入れ溝２０を設けること自体は、負荷できるスラスト力の低下となるが、この例で設ける入れ溝２０は、溝底が内輪５の軌道溝７の溝底に達しない深さとされて浅く、また内輪５および外輪６のうちの内輪５のみに設けるため、入れ溝２０を設けることよるスラスト力の負荷容量の低減よりも、入れ溝２０を設けたことで玉９の数または玉径の増大が得られることによるスラスト力Ｆの負荷容量の増大の方が大きい。そのため、入れ溝２０を設けたことで、却ってスラスト力Ｆの負荷容量が増大する。 Providing the insertion groove 20 itself reduces the thrust force that can be loaded, but the insertion groove 20 provided in this example is shallow because the groove bottom does not reach the groove bottom of the raceway groove 7 of the inner ring 5. Since it is provided only on the inner ring 5 of the inner ring 5 and the outer ring 6, the number of balls 9 or the ball diameter is increased by providing the insertion groove 20 rather than reducing the load capacity of the thrust force by providing the insertion groove 20. The increase in the load capacity of the thrust force F due to the acquisition is larger. Therefore, by providing the insertion groove 20, the load capacity of the thrust force F is rather increased.

また、この玉軸受１が波動歯車減速機に用いられる用途を考慮すると、玉軸受１は楕円形状のカム４の外周に嵌められることによって楕円に変形させられるが、その楕円形状の短軸位置ではサーキュラスプライン２からフレクスプライン３が径方向に離れていて、非負荷域となり、スラスト力Ｆの作用を受け難い。そのため、楕円形状の短軸位置に前記入れ溝２０が位置するように玉軸受１の内輪５を楕円状のカム４に嵌合させると、入れ溝２０を設けたことによるスラスト力の負荷容量の低下がより一層少なくなり、軸受全体としてのスラスト力の負荷容量が増大する。 Further, considering the use of the ball bearing 1 in the wave gear speed reducer, the ball bearing 1 is deformed into an ellipse by being fitted on the outer circumference of the elliptical cam 4, but at the short axis position of the ellipse. The flexspline 3 is separated from the circular spline 2 in the radial direction, and is in a non-load region, and is not easily affected by the thrust force F. Therefore, when the inner ring 5 of the ball bearing 1 is fitted to the elliptical cam 4 so that the groove 20 is located at the position of the short axis of the elliptical shape, the load capacity of the thrust force due to the provision of the groove 20 is increased. The decrease is further reduced, and the load capacity of the thrust force of the bearing as a whole is increased.

ここで、入れ溝２０を設けることによる、玉入れ時の発生応力の低減につき説明する。図１０は、所定の仕様の玉軸受において、玉を内外輪５，６間に入れるときに生じる外輪６の変形量Δと、外輪６の内径に発生する引張応力σの関係を示す。
玉９を内外輪５，６間に入れるときに内外輪５，６の変形を弾性域内に抑える必要があるため、玉９を入れる必要変形量Δ１だけ変形させたときの応力σ１が、降伏応力σａの例えば８５％以内となるように設計されている。このときの外輪変形量Δと外輪６の内径に発生する引張応力σの関係は、破線で示す曲線ｂとなる。この設計で内輪５に入れ溝２０を設けると、その入れ溝深さｈ分だけ必要変形量が減り、このときの必要変形量はΔ２となる。 Here, the reduction of the stress generated at the time of ball insertion by providing the insertion groove 20 will be described. FIG. 10 shows the relationship between the deformation amount Δ of the outer ring 6 generated when the ball is inserted between the inner and outer rings 5 and 6 and the tensile stress σ generated in the inner diameter of the outer ring 6 in a ball bearing having a predetermined specification.
Since it is necessary to suppress the deformation of the inner and outer rings 5 and 6 within the elastic region when the ball 9 is inserted between the inner and outer rings 5 and 6, the stress σ1 when the ball 9 is deformed by the required deformation amount Δ1 is the yield stress. It is designed to be within, for example, 85% of σa. The relationship between the outer ring deformation amount Δ and the tensile stress σ generated in the inner diameter of the outer ring 6 at this time is a curve b shown by a broken line. When the inner ring 5 is provided with the groove 20 in this design, the required deformation amount is reduced by the depth h of the groove, and the required deformation amount at this time is Δ2.

前記設計と同じ構成の玉軸受１において、玉９の個数を１個増やすと、変形量に対する引っ張り応力の曲線は、曲線ａのように立ち上がり、同じ必要変形量Δ１とすると、外輪内径に発生する引っ張り応力はσ２となり、例えば降伏応力σａの１１６％となる。そのため、玉を入れるときに外輪６が塑性変形してしまう。これに対して入れ溝２０を設けると、必要変形量がΔ２と小さくなり、外輪内径に発生する引っ張り応力がσ３となる。このため、玉９を一つ増やしても、降伏応力σａ未満となって、玉を入れるときの外輪６の変形が弾性域に抑えられる。 In the ball bearing 1 having the same configuration as the above design, when the number of balls 9 is increased by one, the tensile stress curve with respect to the deformation amount rises as shown by the curve a, and when the same required deformation amount Δ1 is set, it occurs in the inner diameter of the outer ring. The tensile stress is σ2, which is, for example, 116% of the yield stress σa. Therefore, the outer ring 6 is plastically deformed when the ball is inserted. On the other hand, if the groove 20 is provided, the required deformation amount becomes as small as Δ2, and the tensile stress generated in the inner diameter of the outer ring becomes σ3. Therefore, even if the number of balls 9 is increased by one, the yield stress is less than σa, and the deformation of the outer ring 6 when the balls are inserted is suppressed in the elastic region.

入れ溝２０の断面形状については、前記のように種々の形状を取り得るが、断面形状が図６に示すように円弧状である場合は、玉９の断面形状に近い形状とできて、入れ溝２０の開口幅Ｂを狭くでき、入れ溝２０を設けたことによるスラスト力の負荷容量の低減がより低く抑ええられる。 The cross-sectional shape of the insertion groove 20 can take various shapes as described above, but when the cross-sectional shape is an arc shape as shown in FIG. 6, it can be made into a shape close to the cross-sectional shape of the ball 9 and inserted. The opening width B of the groove 20 can be narrowed, and the reduction in the load capacity of the thrust force due to the provision of the groove 20 can be suppressed to a lower level.

入れ溝２０の断面形状が、図８に示すように内輪５の軸心と平行な平面とした場合、いわゆるＤカット形状とした場合は、円弧溝形状とする場合に比べて、負荷が作用したときの切欠効果による応力集中が生じ難くなる。
入れ溝２０を、図９に示すように、玉９（図１参照）の曲率半径に対して平面と見做せる程度に十分に大きな曲率半径の円弧状とした場合は、平面とした場合と同様に応力集中が生じ難くなる利点が得られる。また、入れ溝２０が平面である場合は、その加工に平面研削盤が必要であるが、大きな曲率半径の円弧状であると、大径の回転砥石を用いて加工でき、入れ溝２０を形成する加工が容易である。 When the cross-sectional shape of the insertion groove 20 is a flat surface parallel to the axis of the inner ring 5 as shown in FIG. 8, when the so-called D-cut shape is used, a load is applied as compared with the case where the arc groove shape is used. Stress concentration is less likely to occur due to the notch effect.
As shown in FIG. 9, when the insertion groove 20 has an arc shape having a radius of curvature sufficiently large enough to be regarded as a plane with respect to the radius of curvature of the ball 9 (see FIG. 1), there is a case where the groove 20 is a plane. Similarly, there is an advantage that stress concentration is less likely to occur. Further, when the groove 20 is flat, a surface grinding machine is required for the processing, but when the groove 20 is arcuate with a large radius of curvature, it can be machined using a large-diameter rotary grindstone to form the groove 20. Easy to process.

前記入れ溝２０の深さｈ（図５）は、前記のように内輪５の軌道溝７の深さＨに対して１０％〜８０％の範囲であることが好ましく、より好ましくは、２０％〜７０％である。入れ溝２０の深さｈは、深くなるに従い、玉９を入れ易くなって玉数・玉径の増大効果が大きくなるが、スラスト力の負荷容量の低減作用が大きくなる。これとは逆に、浅くなるに従い、玉９を入れ難くなり、玉数・玉径の増大効果が小さくなるが、スラスト力の負荷容量の低減作用が小さくなる。入れ溝の深さが前記１０％〜８０％の範囲であれば、玉を入れ易くて、玉数・玉径の増大効果が確保され、かつスラスト力Ｆの負荷容量の低減が抑えられ、総合的に、入れ溝２０を設けながら、スラスト力の負荷容量が増大する。 The depth h of the insertion groove 20 (FIG. 5) is preferably in the range of 10% to 80% with respect to the depth H of the raceway groove 7 of the inner ring 5 as described above, and more preferably 20%. ~ 70%. As the depth h of the insertion groove 20 becomes deeper, it becomes easier to insert the balls 9 and the effect of increasing the number of balls and the diameter of the balls increases, but the effect of reducing the load capacity of the thrust force increases. On the contrary, as it becomes shallower, it becomes more difficult to insert the balls 9, and the effect of increasing the number of balls and the diameter of the balls becomes smaller, but the effect of reducing the load capacity of the thrust force becomes smaller. When the depth of the insertion groove is in the range of 10% to 80%, it is easy to insert balls, the effect of increasing the number of balls and the diameter of the balls is secured, and the reduction of the load capacity of the thrust force F is suppressed. Therefore, the load capacity of the thrust force is increased while providing the insertion groove 20.

次表１は、入れ溝２０の深さｈと、玉の入れ易さと、スラスト力Ｆの負荷容量の関係のシミュレーション結果である。このシミュレーションは、図６のように入れ溝２０の断面形状を円弧状した場合の結果である。結果は「○（良）」、「三角（やや良）」、「×（不良）の３段階で示した。 Table 1 below shows the simulation results of the relationship between the depth h of the insertion groove 20, the ease of inserting a ball, and the load capacity of the thrust force F. This simulation is the result when the cross-sectional shape of the groove 20 is arcuate as shown in FIG. The results are shown in three stages: "○ (good)", "triangular (slightly good)", and "x (bad)".

表１
入れ溝の深さ（ｈ／Ｈ）入れ易さスラスト力Ｆの負荷容量総合判断
０％ × ○ ×
５％ × ○ ×
１０％ △ ○ △
２０％ ○ ○ ○
・・・・・・・・・・・・
７０％ ○ ○ ○
８０％ ○ △ △
９０％ ○ × ×
１００％ ○ × ×
Table 1
Depth of insertion groove (h / H) Ease of insertion Thrust force F load capacity Comprehensive judgment
0% × ○ ×
5% × ○ ×
10% △ ○ △
20% ○ ○ ○
・・・・・・・・・・・・・・・
70% ○ ○ ○
80% ○ △△
90% ○ × ×
100% ○ × ×

次に、この玉軸受１の組み立て方法の一例を示す。この玉軸受１の組み立てを行うときには、まず、図１１に示すように、外輪６に対して内輪５を相対的に径方向に偏心させ、外輪６と内輪５との間に形成された三日月状の隙間に、外輪６の内周面に沿う凸円弧面と内輪５の外周面に沿う凹円弧面とを有する板状部材からなる治具３０を挿入し、この治具３０を周方向の両側から挟む位置に、支点用玉となる玉９を１つずつ外輪６の軌道溝８に沿って配置する。 Next, an example of how to assemble the ball bearing 1 will be shown. When assembling the ball bearing 1, first, as shown in FIG. 11, the inner ring 5 is eccentric in the radial direction relative to the outer ring 6, and a crescent shape formed between the outer ring 6 and the inner ring 5 is formed. A jig 30 made of a plate-like member having a convex arc surface along the inner peripheral surface of the outer ring 6 and a concave arc surface along the outer peripheral surface of the inner ring 5 is inserted into the gap between the two, and the jig 30 is inserted on both sides in the circumferential direction. Balls 9 serving as fulcrum balls are arranged one by one along the raceway groove 8 of the outer ring 6 at a position sandwiched from the outer ring 6.

その後、図１２に示すように、外輪６と内輪５とを同心となるまで移動させることにより、２つの支点用玉９が、外輪６の軌道溝８と内輪５の軌道溝７との間に所定の角度間隔θをおいて配置されることになる。
このとき、内輪６の入れ溝２０は前記所定の角度間隔θの範囲から外れ、かつ前記所定の角度間隔θの中央から９０°離れた箇所までの範囲に入る位置(例えば、領域Ａ内)とする。 After that, as shown in FIG. 12, by moving the outer ring 6 and the inner ring 5 until they are concentric, the two fulcrum balls 9 are placed between the raceway groove 8 of the outer ring 6 and the raceway groove 7 of the inner ring 5. They will be arranged at a predetermined angular interval θ.
At this time, the groove 20 of the inner ring 6 is located at a position (for example, in the region A) that deviates from the range of the predetermined angle interval θ and enters a range 90 ° away from the center of the predetermined angle interval θ. To do.

ここで、治具３０の厚み寸法Ｔは、外輪６の内径をＤ１、外輪６の軌道溝８の溝底径をＤ２、内輪５の外径をｄ１、内輪５の軌道溝７の溝底径をｄ２とするとき、
Ｔ≦３／２（Ｄ１−ｄ１）−（Ｄ２−ｄ２）・・・（１）
となるように設定され、治具３０と外輪６および内輪５との間にわずかな径方向隙間が生じるようになっている。また、治具３０の周方向長さ寸法は、治具３０を挟み付ける２つの支点用の玉９の角度間隔θが７０〜９０°となるように設定されている。 Here, the thickness dimension T of the jig 30 is such that the inner diameter of the outer ring 6 is D1, the groove bottom diameter of the raceway groove 8 of the outer ring 6 is D2, the outer diameter of the inner ring 5 is d1, and the groove bottom diameter of the raceway groove 7 of the inner ring 5. When is d2
T ≦ 3/2 (D1-d1)-(D2-d2) ・・・ (1)
A slight radial gap is formed between the jig 30, the outer ring 6 and the inner ring 5. Further, the circumferential length dimension of the jig 30 is set so that the angular distance θ between the two fulcrum balls 9 sandwiching the jig 30 is 70 to 90 °.

次に、図１２に示すように、外輪６および内輪５に、両支点用の玉９の角度間隔θの中央位置付近で、外輪６と内輪５の径方向隙間を狭める方向（図中の白抜き矢印方向）の荷重を加えて、外輪６と内輪５を弾性変形させる。 Next, as shown in FIG. 12, the direction in which the radial gap between the outer ring 6 and the inner ring 5 is narrowed in the outer ring 6 and the inner ring 5 near the center position of the angular distance θ of the balls 9 for both fulcrums (white in the figure). The outer ring 6 and the inner ring 5 are elastically deformed by applying a load (in the direction of the pull-out arrow).

このときの外輪６と内輪５の弾性変形による径方向隙間の変化を、解析によって求めた。その解析の結果を図１５に示す。なお、解析は図１２の左右対称な条件で行ったので、周方向の半分のみを記載している。この図１５では、外輪６および内輪５に荷重を加える位置（４０°付近）から荷重が加えられる反対側の角度間隔で３０〜５０°離れた位置（（７０〜９０°）付近、図１２中の領域Ａ付近）で、外輪６と内輪５の径方向隙間が最も広がっている。 The change in the radial gap due to the elastic deformation of the outer ring 6 and the inner ring 5 at this time was obtained by analysis. The result of the analysis is shown in FIG. Since the analysis was performed under the symmetrical conditions shown in FIG. 12, only half of the circumferential direction is shown. In FIG. 15, the position where the load is applied to the outer ring 6 and the inner ring 5 (near 40 °) is separated from the position where the load is applied by 30 to 50 ° (near (70 to 90 °)) at an angular interval on the opposite side, in FIG. The radial gap between the outer ring 6 and the inner ring 5 is the widest in the region A).

したがって、図１２に示すように、外輪６および内輪５に適切な荷重を加えて、周方向の２箇所のいずれかの領域Ａ付近で、外輪６と内輪１２の径方向の隙間に入れ溝２０の深さｈ（図５参照）を加えた隙間量を玉９の直径より大きくなるようにした状態で、前記領域Ａにある入れ溝２０から、支点用玉９以外の玉９を、外輪６の軌道溝８と内輪５の軌道溝７との間に入れていけばよい。
なお、入れ溝２０は、２箇所の前記領域Ａに位置するように、内輪５の円周方向の２箇所に設けてもよく、その場合、２箇所から残りの玉９を入れることができる。 Therefore, as shown in FIG. 12, an appropriate load is applied to the outer ring 6 and the inner ring 5, and a groove 20 is formed in the radial gap between the outer ring 6 and the inner ring 12 in the vicinity of any of the two regions A in the circumferential direction. In a state where the gap amount to which the depth h (see FIG. 5) is added is larger than the diameter of the ball 9, the ball 9 other than the fulcrum ball 9 is removed from the insertion groove 20 in the region A, and the outer ring 6 is used. It may be inserted between the raceway groove 8 of the above and the raceway groove 7 of the inner ring 5.
The insertion grooves 20 may be provided at two locations in the circumferential direction of the inner ring 5 so as to be located at the two locations of the region A, and in that case, the remaining balls 9 can be inserted from the two locations.

また、図１５から、周方向位置が７０〜９０°付近の隙間変化量は、外輪６および内輪５に加える荷重の大きさにつれて変化するが、荷重レベルによらず荷重位置（０°の位置）の隙間変化量の１／２程度の大きさになることが分かる。したがって、この解析結果から、図１２中の領域Ａ付近で外輪６と内輪５の径方向の隙間に入れ溝２０の深さｈを加えた値が玉９の直径よりも大きくなるときの荷重位置の隙間変化量を推定し、これに応じて、治具３０の厚み寸法Ｔを前記（１）式の範囲で設定し、外輪６と内輪５を弾性変形させるときには、その弾性変形によって治具３０を径方向で挟み付けるまで荷重を加えるようにすれば、荷重の管理を行わなくても、残りの玉９を入れられる状態を容易に実現することができ、作業効率の向上が図れる。 Further, from FIG. 15, the amount of change in the gap in the circumferential position near 70 to 90 ° changes according to the magnitude of the load applied to the outer ring 6 and the inner ring 5, but the load position (0 ° position) regardless of the load level. It can be seen that the magnitude of the change in the gap is about 1/2. Therefore, from this analysis result, the load position when the value obtained by adding the depth h of the groove 20 to the radial gap between the outer ring 6 and the inner ring 5 near the region A in FIG. 12 becomes larger than the diameter of the ball 9. When the thickness dimension T of the jig 30 is set within the range of the above equation (1) and the outer ring 6 and the inner ring 5 are elastically deformed according to the estimation of the amount of change in the gap, the jig 30 is elastically deformed. If the load is applied until the ball 9 is sandwiched in the radial direction, it is possible to easily realize a state in which the remaining balls 9 can be inserted without managing the load, and the work efficiency can be improved.

上記の組み立て方法で組み立てられた玉軸受１では、図１３に示すように、玉９の充填率（α／３６０）×１００が８０％以上に達し、波動歯車減速機の内周側に組み込まれるのに適したものになっている。 In the ball bearing 1 assembled by the above assembly method, as shown in FIG. 13, the filling rate (α / 360) × 100 of the ball 9 reaches 80% or more and is incorporated in the inner peripheral side of the strain wave gearing reducer. It is suitable for.

この玉軸受の組立方法は、上述したように、まず、外輪６と内輪５の間に２つの支点用玉９を所定の角度間隔θをおいて配置し、このとき内輪６の入れ溝２０は前記所定の角度間隔θの範囲から外れ、かつ前記所定の角度間隔θの中央から９０°離れた箇所までの範囲に入る位置とする。次に、両支点用玉９の角度間隔θの中央位置付近で、外輪６と内輪５にその径方向隙間を狭める方向の荷重を加えることにより、周方向の２箇所の領域Ａのいずれかに位置させた入れ溝２０から残りの玉９を外輪６と内輪５の間に入れているようにした方法であり、通常の深溝玉軸受の組立方法よりも充填率高めることができる。
この実施形態の玉軸受１にこの組立方法を適用することで、組み込み性を向上させながら、より一層スラスト力の負荷容量に優れた玉軸受１を製造することができる。 As described above, in the method of assembling the ball bearing, first, two fulcrum balls 9 are arranged between the outer ring 6 and the inner ring 5 at a predetermined angular interval θ, and at this time, the groove 20 of the inner ring 6 is formed. The position is defined as a position that deviates from the range of the predetermined angular interval θ and enters a range 90 ° away from the center of the predetermined angular interval θ. Next, by applying a load in the direction of narrowing the radial gap between the outer ring 6 and the inner ring 5 near the center position of the angular distance θ between the two fulcrum balls 9, one of the two regions A in the circumferential direction is applied. This is a method in which the remaining balls 9 are inserted between the outer ring 6 and the inner ring 5 from the positioned insertion groove 20, and the filling rate can be increased as compared with the usual method of assembling a deep groove ball bearing.
By applying this assembly method to the ball bearing 1 of this embodiment, it is possible to manufacture the ball bearing 1 which is further excellent in the load capacity of the thrust force while improving the assembling property.

以上、実施形態に基づいて本発明を実施するための形態を説明したが、ここで開示した実施の形態はすべての点で例示であって制限的なものではない。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 Although the embodiments for carrying out the present invention have been described above based on the embodiments, the embodiments disclosed here are examples in all respects and are not limiting. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

１…玉軸受
２…サーキュラスプライン
３…フレクスプライン
４…カム
５…内輪
６…外輪
７，８…軌道溝
９…玉
１６…玉軸受付きカム
１７…肩面
２０…入れ溝
Ｈ…軌道溝の深さ
ｈ…入れ溝の深さ 1 ... Ball bearing 2 ... Circular spline 3 ... Flex spline 4 ... Cam 5 ... Inner ring 6 ... Outer ring 7, 8 ... Track groove 9 ... Ball 16 ... Cam with ball bearing 17 ... Shoulder surface 20 ... Insert groove H ... Depth of raceway groove H ... Depth of the groove

Claims

内輪および外輪と、これら内輪および外輪の対向する軌道溝間に円周方向に並んで介在する複数の玉とを備え、
前記内輪および外輪は、自然状態で円形であって非円形に変形可能な弾性を有し、
前記内輪および外輪のうちの内輪のみに、前記軌道溝を除く外周面部分である肩面に、前記内輪の幅面から前記軌道溝に続いて、軸受外部から内外輪の前記軌道溝間に前記玉を入れる入れ溝が設けられ、
この入れ溝は、溝底が前記内輪の軌道溝の溝底に達しない深さとされた、玉軸受。 It is provided with an inner ring and an outer ring, and a plurality of balls interposed between the inner ring and the outer ring facing raceway grooves in a circumferential direction.
The inner ring and the outer ring have elasticity that is circular in a natural state and can be deformed into a non-circular shape.
Only on the inner ring of the inner ring and the outer ring, on the shoulder surface which is the outer peripheral surface portion excluding the raceway groove, from the width surface of the inner ring to the raceway groove, and between the bearing outer side and the raceway groove of the inner and outer rings, the ball. There is a groove to put in
This insertion groove is a ball bearing having a depth at which the groove bottom does not reach the groove bottom of the raceway groove of the inner ring.

請求項１に記載の玉軸受において、前記入れ溝は、断面形状が円弧状である玉軸受。 In the ball bearing according to claim 1, the groove is a ball bearing having an arcuate cross-sectional shape.

請求項１に記載の玉軸受において、前記入れ溝は、断面形状が、前記内輪の軸心と平行な平面、または前記玉の曲率半径に対して平面と見做せる程度に十分に大きな曲率半径の円弧状である玉軸受。 In the ball bearing according to claim 1, the groove has a radius of curvature sufficiently large so that the cross-sectional shape can be regarded as a plane parallel to the axis of the inner ring or a plane with respect to the radius of curvature of the ball. Ball bearings that are arcuate.

請求項１ないし請求項３のいずれか１項に記載の玉軸受において、前記入れ溝の深さが、前記内輪の前記軌道溝に深さに対して１０％〜８０％の範囲である玉軸受。 In the ball bearing according to any one of claims 1 to 3, the depth of the insertion groove is in the range of 10% to 80% with respect to the depth of the raceway groove of the inner ring. ..

請求項１ないし請求項４のいずれか１項に記載の玉軸受において、深溝玉軸受である玉軸受。 The ball bearing according to any one of claims 1 to 4, which is a deep groove ball bearing.

請求項１ないし請求項５のいずれか１項に記載の玉軸受において、波動歯車減速機に備わる楕円状のカムの外周に前記内輪が嵌合し、フレクスプラインの内周に前記外輪が嵌合し、前記カムの楕円形状の短軸の位置付近に前記入れ溝が位置するように用いられる玉軸受。
In the ball bearing according to any one of claims 1 to 5, the inner ring is fitted on the outer circumference of an elliptical cam provided in the wave gear reducer, and the outer ring is fitted on the inner circumference of the flexspline. A ball bearing used so that the groove is located near the position of the elliptical short axis of the cam.