JP3838313B2

JP3838313B2 - Ball bearing

Info

Publication number: JP3838313B2
Application number: JP36854898A
Authority: JP
Inventors: 大和新井
Original assignee: JTEKT Corp
Current assignee: JTEKT Corp
Priority date: 1998-12-09
Filing date: 1998-12-09
Publication date: 2006-10-25
Anticipated expiration: 2018-12-09
Also published as: JP2000170773A

Description

【０００１】
【発明の属する技術分野】
本発明は、高速回転装置、例えばデンタルハンドピースに使用される玉軸受に関する。
【０００２】
【従来の技術】
従来のデンタルハンドピースに使用される玉軸受は、内輪と、外輪と、内外輪間に配置した玉と、環体の一端側で軸方向に開口し玉を保持する球面状ポケットを円周上複数個形成した合成樹脂製冠形保持器とを有している。上記玉は、ポケットの開口部に形成された爪部にてポケット内に保持されている。
【０００３】
【発明が解決しようとする課題】
上記の従来の玉軸受においては、高速回転時（例えば４０万回転時）の保持器振れを防止するため、保持器内周面と内輪外周面との隙間を極力小さくすることが行われている。しかし、高速回転による軸受内部の温度上昇が発生し、この時、冠形保持器が合成樹脂製であることから、保持器が熱収縮による寸法収縮を生じて保持器内周面が内輪外周面に抱き着き、回転抵抗が非常に大きくなり、その結果、軸受の回転数が減少して軸受の使用ができなくなるという問題点があった。
【０００４】
そこで、この発明は、合成樹脂製冠形保持器の熱収縮による寸法収縮が生じても、保持器の内輪への抱き着きを防止し、回転抵抗を極力抑える玉軸受を提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明は上記課題を解決することを目的とし、内輪と、外輪と、内外輪間に配置した玉と、環体の一端側で軸方向に開口し玉を保持する球面状ポケットを円周上複数個形成した合成樹脂製冠形保持器とを有する転がり軸受において、上記内輪外周面と保持器内周面とをそれぞれ軸受軸線に平行な円筒面とするとともに、上記保持器内周面に、上記保持器環体の一端面から他端面に向けて連続して軸方向に延びて、内周側先端が内輪外周面との間に隙間を有し、熱収縮による寸法収縮時に内輪外周面に接触する半円柱状の突条リブを形成したことを特徴とする。
【０００６】
また、上記突条リブを、ポケット間の柱部内周面に形成したことを特徴する。
【０００７】
さらにまた、上記突条リブを、円周均等になるよう複数の柱部内周面に形成したことを特徴する。
【０００８】
さらにまた、上記突条リブを、全柱部内周面に形成したことを特徴する。
【００１０】
本発明は、内輪と、外輪と、内外輪間に配置した玉と、環体の一端側で軸方向に開口し玉を保持する球面状ポケットを円周上複数個形成した合成樹脂製冠形保持器とを有する転がり軸受において、上記内輪外周面と保持器内周面とをそれぞれ軸受軸線に平行な円筒面とするとともに、上記保持器内周面に、上記保持器環体の一端面から他端面に向けて不連続に軸方向に延びる複数のリブを形成したことを特徴とする。
【００１１】
【発明の実施の形態】
以下、この発明の具体的実施の形態について図面を参照して説明する。
図１において、内輪１と外輪２間に、複数の玉３が合成樹脂製冠形保持器４に円周等配に保持されて介装されている。この合成樹脂製冠形保持器４は、環体５の一端側で軸方向に開口した円周上複数個の球面状ポケット７を有し、各ポケット７内に上記各玉３が保持されている。また、各ポケット７の開口部８にはその開口間隔Ａが玉３の直径よりも小さくされた爪部９，１０が形成され、玉３の脱落を防止している。さらに、保持器４内周面４ａと内輪１外周面１ａは、それぞれ軸受軸線に平行な円筒面にて形成されている。
【００１２】
そして、上記合成樹脂製冠形保持器４は、図２においてさらに良く理解されるように、ポケット７間の柱部５ａ内周面に、軸受軸線に平行な突起６が形成され、内輪１外周面１ａにて回転案内される。この内輪外周面１ａ、保持器内周面４ａおよび突起内周面６ａがいずれも軸受軸線に平行であるため、突起内周面６ａと内輪外周面１ａとの隙間を極力小さくできる。また、この突起６は、全ての柱部５ａ内周面に形成してもよく、あるいは円周均等になるよう複数の柱部５ａ内周面に形成してもよい。全ての柱部５ａ内周面に突起６を形成した場合には、軸受温度上昇時の保持器４の熱収縮による寸法収縮の影響を極力抑えることができる。また、複数の柱部５ａ内周面に突起６を形成した場合は、上記全ての柱部５ａ内周面に突起６を形成した場合に比べて熱収縮防止効果ではやや劣るものの、寸法収縮時の内輪１に対する接触面積が小さい点で有利である。
【００１３】
また、上記突起６形状は、図１および図２のように、保持器環体５の一端面から他端面に向けて連続して軸方向に延びる突条リブとされている。この突条リブ６は円柱状で頂面が軸受軸線に平行とされている。上記の連続する突条リブ６とすることにより、射出成形が容易に行える。
【００１４】
さらに、図３に示すように、突起形状を保持器環体５に一端面から他端面に向けて不連続に軸方向に延びる複数のリブ１１としてもよい。この複数のリブ１１はそれぞれ同一高さで、内周面が軸線に平行とされている。上記複数リブ１１とすることにより、射出成形はやや複雑となるが、保持器の寸法収縮時の接触面積が小さいという有利さがある。
【００１５】
なお、上記各実施形態に限らず、突起箇所、突起形状の変更は本発明の範囲内にて行うことができるものである。
【００１６】
【発明の効果】
このように、本発明では、軸受温度上昇時の保持器の熱収縮による寸法収縮が生じても、突条リブもしくは複数のリブが内輪に接触するだけであるので、保持器の内輪に対する抱き着きが防止される。そのため、保持器の突条リブもしくは複数のリブの内周面と内輪外周面の隙間を小さくでき、高速回転時の保持器振れを防止できる。
【図面の簡単な説明】
【図１】本発明の一実施形態の玉軸受の断面図である。
【図２】本発明における合成樹脂製保持器の一実施形態の斜視図である。
【図３】本発明における合成樹脂製保持器の他の実施形態の斜視図である。
【符号の説明】
１内輪
２外輪
３玉
４保持器
５環体
６突起
７ポケット
８開口部
９爪部
１０爪部
１１リブ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ball bearing used for a high-speed rotating device, for example, a dental handpiece.
[0002]
[Prior art]
Ball bearings used in conventional dental handpieces have an inner ring, an outer ring, a ball arranged between the inner and outer rings, and a spherical pocket that opens in the axial direction on one end of the ring and holds the ball on the circumference. And a plurality of synthetic resin crown-shaped cages. The ball is held in the pocket by a claw formed in the opening of the pocket.
[0003]
[Problems to be solved by the invention]
In the conventional ball bearing described above, in order to prevent cage runout during high-speed rotation (for example, 400,000 revolutions), the gap between the cage inner circumferential surface and the inner ring outer circumferential surface is made as small as possible. . However, the temperature inside the bearing increases due to high-speed rotation. At this time, the crown-shaped cage is made of synthetic resin, so the cage causes dimensional shrinkage due to thermal shrinkage, and the cage inner circumferential surface is the inner ring outer circumferential surface. As a result, the rotational resistance becomes very large, and as a result, the number of rotations of the bearing decreases and the bearing cannot be used.
[0004]
Accordingly, an object of the present invention is to provide a ball bearing that prevents the cage from being stuck to the inner ring and suppresses the rotational resistance as much as possible even when dimensional shrinkage occurs due to thermal shrinkage of the synthetic resin crown-shaped cage. To do.
[0005]
[Means for Solving the Problems]
An object of the present invention is to solve the above-mentioned problems. An inner ring, an outer ring, a ball arranged between the inner and outer rings, and a spherical pocket that opens in the axial direction on one end side of the ring body and holds the ball on the circumference. In a rolling bearing having a plurality of synthetic resin crown-shaped cages, the inner ring outer circumferential surface and the cage inner circumferential surface are each a cylindrical surface parallel to the bearing axis, and the cage inner circumferential surface, The cage ring continuously extends from one end surface to the other end surface in the axial direction, and the inner circumferential tip has a gap with the outer circumferential surface of the inner ring. It is characterized in that a semi-cylindrical protruding rib is formed.
[0006]
In addition, the protruding rib is formed on the inner peripheral surface of the column portion between the pockets.
[0007]
Furthermore, the protruding ribs are formed on the inner peripheral surfaces of the plurality of pillars so as to be even in the circumference .
[0008]
Furthermore, the protruding ribs are formed on the inner peripheral surface of all the pillars.
[0010]
The present invention is a synthetic resin crown having an inner ring, an outer ring, a ball disposed between the inner and outer rings, and a plurality of spherical pockets on the circumference that open in the axial direction on one end side of the ring body and hold the ball. In a rolling bearing having a cage, the inner ring outer circumferential surface and the cage inner circumferential surface are respectively cylindrical surfaces parallel to the bearing axis, and the cage inner circumferential surface is connected to one end surface of the cage ring. A plurality of ribs extending in the axial direction discontinuously toward the other end surface are formed.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, a plurality of balls 3 are interposed between an inner ring 1 and an outer ring 2 while being held by a synthetic resin crown-shaped cage 4 at an equal circumference. The synthetic resin crown-shaped cage 4 has a plurality of spherical pockets 7 on the circumference that are opened in the axial direction on one end side of the ring body 5, and the balls 3 are held in the pockets 7. Yes. Further, claw portions 9 and 10 having an opening interval A smaller than the diameter of the ball 3 are formed in the opening 8 of each pocket 7 to prevent the ball 3 from dropping off. Furthermore, the inner peripheral surface 4a of the cage 4 and the outer peripheral surface 1a of the inner ring 1 are each formed by a cylindrical surface parallel to the bearing axis.
[0012]
In the synthetic resin crown-shaped cage 4, as can be better understood in FIG. 2, protrusions 6 parallel to the bearing axis are formed on the inner peripheral surface of the column portion 5 a between the pockets 7, and the outer periphery of the inner ring 1 It is guided to rotate on the surface 1a. Since the inner ring outer circumferential surface 1a, the cage inner circumferential surface 4a and the projection inner circumferential surface 6a are all parallel to the bearing axis, the gap between the projection inner circumferential surface 6a and the inner ring outer circumferential surface 1a can be minimized. Further, the protrusions 6 may be formed on all the inner peripheral surfaces of the column portions 5a, or may be formed on the inner peripheral surfaces of the plurality of column portions 5a so as to be equal in circumference. When the protrusions 6 are formed on the inner peripheral surfaces of all the column portions 5a, the influence of dimensional shrinkage due to the thermal shrinkage of the cage 4 when the bearing temperature rises can be suppressed as much as possible. In addition, when the protrusions 6 are formed on the inner peripheral surfaces of the plurality of column parts 5a, the heat shrinkage prevention effect is slightly inferior to the case where the protrusions 6 are formed on the inner peripheral surfaces of all the column parts 5a. This is advantageous in that the contact area with the inner ring 1 is small.
[0013]
Further, as shown in FIGS. 1 and 2, the shape of the protrusion 6 is a protruding rib that continuously extends in the axial direction from one end surface of the cage ring 5 toward the other end surface. The projecting rib 6 is cylindrical and has a top surface parallel to the bearing axis. By using the above-described continuous rib 6, injection molding can be easily performed.
[0014]
Furthermore, as shown in FIG. 3, the protrusion shape may be a plurality of ribs 11 extending discontinuously in the axial direction from one end surface to the other end surface of the retainer ring body 5. The plurality of ribs 11 have the same height, and the inner peripheral surface is parallel to the axis. By using the plurality of ribs 11, the injection molding becomes somewhat complicated, but there is an advantage that the contact area when the size of the cage is reduced is small.
[0015]
In addition, not only each said embodiment but a change of a protrusion location and protrusion shape can be performed within the scope of the present invention.
[0016]
【The invention's effect】
Thus, in the present invention, even if dimensional shrinkage occurs due to thermal shrinkage of the cage when the bearing temperature rises, the rib or the plurality of ribs only come into contact with the inner ring. Is prevented. Therefore, the clearance gap between the inner peripheral surface of the protrusion rib or the plurality of ribs of the cage and the outer peripheral surface of the inner ring can be reduced, and the cage shake during high-speed rotation can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a ball bearing according to an embodiment of the present invention.
FIG. 2 is a perspective view of an embodiment of a synthetic resin cage according to the present invention.
FIG. 3 is a perspective view of another embodiment of the synthetic resin cage in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Ball 4 Cage 5 Ring body 6 Projection 7 Pocket 8 Opening part 9 Claw part 10 Claw part 11 Rib

Claims

An inner ring, an outer ring, a ball disposed between the inner and outer rings, and a synthetic resin crown-shaped cage having a plurality of spherical pockets on the circumference that open in the axial direction on one end side of the ring and hold the ball. In a rolling bearing having
The outer peripheral surface of the inner ring and the inner peripheral surface of the cage are respectively cylindrical surfaces parallel to the bearing axis, and the shaft is continuously connected to the inner peripheral surface of the cage from one end surface to the other end surface of the cage ring. A ball having a semi-cylindrical ridge rib that extends in the direction and has a gap between the inner peripheral end and the outer peripheral surface of the inner ring and that contacts the outer peripheral surface of the inner ring when dimensional contraction occurs due to thermal contraction. bearing.

The ball bearing according to claim 1, wherein the protrusion rib is formed on the inner peripheral surface of the column portion between the pockets.

The ball bearing according to claim 2, wherein the protrusion rib is formed on the inner peripheral surface of the plurality of column portions so as to be even in the circumference .

The ball bearing according to claim 2, wherein the ribs are formed on the inner peripheral surface of all the pillars.

An inner ring, an outer ring, a ball disposed between the inner and outer rings, and a synthetic resin crown-shaped cage having a plurality of spherical pockets on the circumference that open in the axial direction on one end side of the ring and hold the ball. In a rolling bearing having
The outer peripheral surface of the inner ring and the inner peripheral surface of the cage are respectively cylindrical surfaces parallel to the bearing axis, and the shaft is discontinuously disposed on the inner peripheral surface of the cage from one end surface of the cage ring to the other end surface. A ball bearing comprising a plurality of ribs extending in a direction.