JP2008256086A - Ball bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ball bearing hardly causing damage to a separator. <P>SOLUTION: A deep groove ball bearing is provided with an inner ring 1, an outer ring 2, a plurality of balls 3 rollingly disposed between the inner ring 1 and the outer ring 2, and separators 4 formed of a solid lubricating agent for keeping an interval between the balls 3. The separator 4 is a substantially annular member, and includes through-holes 4a for storing the balls 3 at the substantial center thereof. Every other one of the plurality of balls 3 aligned in a circle is disposed in the through-hole 4a of the separator 4. Namely, the ball 3 with the separator 4 attached thereto and the ball 3 without the separator 4 are alternately aligned. In the deep groove ball bearing, a bearing outer diameter D, a bearing inner diameter d, and a bearing width B satisfy two expressions of: 0.60<B/ä(D-d)/2}<1.2 and 0.39<(D-d)/2/d<0.91. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ball bearing including a separator.

Since the flat panel display (FPD) transfer device and the transfer robot are normally used in a vacuum environment, the bearings used for the transfer device and the transfer robot are also designed for vacuum. For example, fluorine grease that is low outgas or solid lubricant that is low outgas is used as a bearing lubricant.
Patent Document 1 discloses a ball bearing in which a donut-shaped separator made of a solid lubricant is fitted to all balls (see FIGS. 10 and 11). In this ball bearing, when the ball and the separator slide, a part of the separator is transferred to the ball, and the transferred solid lubricant contributes to lubrication of the ball and the raceway surface.

On the other hand, since the size of FPD is increasing, the size of the transfer device and the transfer robot for transferring the FPD is increased, and the bearings used for the transfer device and the transfer robot are required to have a performance capable of withstanding a high load. . As ball bearings for high load applications, there are bearings that satisfy the following two expressions. Here, D in the equation is a bearing outer diameter, d is a bearing inner diameter, and B is a bearing width.
0.60 <B / {(D−d) / 2} <1.2
0.39 <(D−d) / 2 / d <0.91
Japanese Patent Publication No. 1-28248

  Since the above-described ball bearings for high load use have a large rated load and a high capacity, the ball diameter is large with respect to the longitudinal sectional area of the bearing. Therefore, the interval between balls is narrow. Therefore, when the ball bearing disclosed in Patent Document 1 is used for a high load, in order to fit the separator to all the balls, the thickness of the separator (the difference between the outer diameter and the inner diameter of the annular separator is 1). / 2) needs to be thinned.

However, if the separator is thin, there is a problem that damage such as cracking is likely to occur when the separators collide with each other or when the separator is sandwiched between balls and receives a load. If the crack occurs, a part of the chipped separator may be bitten and the ball bearing may not be able to rotate.
Then, this invention solves the problem which the above conventional ball bearings have, and makes it a subject to provide the ball bearing which a damage is hard to produce to a separator.

In order to solve the above problems, the present invention has the following configuration. That is, the ball bearing of claim 1 according to the present invention is an inner ring, an outer ring, a plurality of balls arranged to roll between the inner ring and the outer ring, and a solid lubricant that keeps a space between the balls. In the ball bearing provided with the separator made of, the separator has a through hole that accommodates the ball, and the plurality of balls arranged in a circle are arranged in the through hole of the separator every other one. In addition, the bearing outer diameter D, the bearing inner diameter d, and the bearing width B satisfy the following two expressions.
0.60 <B / {(D−d) / 2} <1.2
0.39 <(D−d) / 2 / d <0.91

  The ball bearing according to claim 2 of the present invention is the ball bearing according to claim 1, wherein the outer peripheral portion of the separator is formed with arc-shaped recesses facing the adjacent balls on both sides, The radius of curvature of the recess is larger than the radius of the ball, and the sum of the product of the distance between the bottoms of the two recesses and the number of separators and the product of the diameter of the balls and the number of balls is It is characterized by being 80% or more of the pitch diameter of the ball set.

  Furthermore, the ball bearing according to claim 3 of the present invention is the ball bearing according to claim 1 or 2, wherein the ball bearing is an angular ball bearing and both flat surfaces in which the through holes of the substantially plate-like separator are opened. One of them has an inclined surface that is inclined in a direction perpendicular to a straight line connecting the bottoms of the two recesses, and the thicker side of the separator is arranged on the counterbore side (the part from which the shoulder is removed). It is characterized by being.

  Furthermore, the ball bearing of Claim 4 which concerns on this invention is a ball bearing as described in any one of Claims 1-3, The said solid lubricant is metal at least one of molybdenum disulfide and tungsten disulfide. It is characterized by being a sintered metal mixed and sintered, or a composite material comprising at least one of molybdenum disulfide and tungsten disulfide, polytetrafluoroethylene, and polyetheretherketone.

  In the ball bearing of the present invention, the separator is hardly damaged.

DESCRIPTION OF EMBODIMENTS Embodiments of a ball bearing according to the present invention will be described in detail with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals.
[First embodiment]
The deep groove ball bearings shown in FIGS. 1 and 2 are made of a solid lubricant that maintains an interval between the inner ring 1, the outer ring 2, a plurality of balls 3 that are freely rollable between the inner ring 1 and the outer ring 2, and the balls 3. The separator 4 is provided. The separator 4 is a substantially annular member, and has a through hole 4a that accommodates the ball 3 at substantially the center thereof. A plurality of balls 3 arranged in a circle are disposed in every other through hole 4 a of the separator 4. That is, the balls 3 on which the separators 4 are mounted and the balls 3 on which the separators 4 are not mounted are alternately arranged.

Further, this deep groove ball bearing has the following two expressions in the bearing outer diameter D, the bearing inner diameter d, and the bearing width B.
0.60 <B / {(D−d) / 2} <1.2
0.39 <(D−d) / 2 / d <0.91

  In such a deep groove ball bearing, not all the balls 3 are equipped with the separators 4 but every other one, so that the thickness of the separators 4 (the outer diameter and the inner diameter of the substantially annular separator 4). Can be set thick. Therefore, even when the separators 4 collide with each other or when the separators 4 are sandwiched between the balls 3 and receive a load, damage such as cracking is unlikely to occur, so that the deep groove ball bearing is suitable for high load applications. When the number of balls 3 is an odd number, two balls 3 on which separators 4 are mounted are arranged at one place in the row of balls 3.

  Moreover, since this deep groove ball bearing is lubricated with the solid lubricant transferred from the separator 4, it is low outgas. Therefore, it can be suitably used even in a vacuum environment. As for the lubrication of the balls 3 to which the separators 4 are not mounted, the solid lubricant is transferred when contacting the separators 4 mounted on the adjacent balls 3 or the solid lubricants from the raceways of the inner ring 1 and the outer ring 2. Is transferred and lubricated, so there is no lack of lubrication. Moreover, since the transition of the solid lubricant occurs immediately after the start of the rotation of the deep groove ball bearing, there is no lack of lubrication at the beginning of the rotation of the deep groove ball bearing.

Such ball bearings suitable for high load applications and vacuum applications can be used for FPD transfer devices and transfer robots.
In addition, when the kind of ball bearing is a deep groove ball bearing, it is preferable to provide a groove in the inner ring 1 and the outer ring 2. Then, it is easy to load the ball 3 into the bearing, and the ball 3 can be loaded with the separator 4 mounted.

[Second Embodiment]
The ball bearing according to the second embodiment shown in FIGS. 3 to 5 has substantially the same configuration as the deep groove ball bearing according to the first embodiment except that the shape of the separator is different. Description is omitted.
On the outer peripheral portion of the separator 4, arc-shaped concave portions 5, 5 that face both adjacent balls 3, 3 are formed. That is, as shown in FIG. 5A, the separator 4 has a substantially rectangular plate shape, and arc-shaped concave portions 5 and 5 are formed on opposite sides of the separator 4. The radius of curvature of the recess 5 is set larger than the radius of the ball 3.

  If such a recess 5 is formed, the adjacent balls 3 are fitted into the recess 5, so that all the separators 4 and all the balls 3 are connected (see FIGS. 3 and 4). The separator 4 does not rotate around the ball 3 in the through hole 4a. Furthermore, since the contact between the separator 4 and the ball 3 occurs in the recess 5, the contact surface pressure is small. Furthermore, since all the separators 4 and all the balls 3 are in a connected state, and the contact between the separators 4 and the balls 3 always occurs in the concave portions 5 of the separators 4, the contact between the separators 4 and the balls 3. Surface pressure is always kept low.

  In order for all the separators 4 and all the balls 3 to be connected, the distance L between the bottoms of the two recesses 5 and 5 (the distance between the bottom 5a and the bottom 5a of the recesses 5) and the separator The sum of two values of the product of the number of 4 and the product of the diameter of the ball 3 and the number of the balls 3 needs to be 80% or more of the pitch diameter of the ball set. If this numerical value is less than 80% of the pitch diameter of the ball set, the ball 3 is likely to be detached from the recess 5, and there may be a case where not all the separators 4 and all the balls 3 are connected. .

  When the balls 3 are loaded into the bearings, the balls 3 with the separators 4 mounted thereon and the balls 3 with no separators mounted thereon are alternately loaded from an insertion groove (not shown). In order for the last loaded ball 3 to fit into the recess 5 of the separator 4, the separator 4 mounted on the ball 3 adjacent to the last ball 3 is shaped like a separator 4 </ b> B shown in FIG. It is necessary to have done. That is, in the separator 4B, unlike the separator 4 shown in FIG. 5A, one of the two recesses 5 is linearly formed by removing one of the two shoulders 5b forming the recess 5. Yes.

  The ball 3 with the separator 4B having such a shape is inserted, the shoulder 5b of the separator 4B is removed, and the side that is straight is inserted into the groove side (that is, the side of the separator 4B on which the shoulder 5b is located). If the last ball 3 is loaded after that, the last ball 3 is loaded into the deep groove ball bearing along the straight portion described above and held in the recess 5. It will be.

[Third embodiment]
The ball bearing of the third embodiment shown in FIGS. 6 to 8 is substantially the same as the deep groove ball bearing of the first embodiment except that it is an angular ball bearing and the shape of the separator is different. Only the description will be given, and description of similar parts will be omitted.
If the type of ball bearing is an angular ball bearing, it can be assembled without providing a slot. That is, the outer ring 2 (which may be the inner ring 1) is a counterbore and one shoulder is removed, so that the inner ring 1 temporarily integrated with the ball 3 can be assembled by shrink fitting. At this time, the separator 4 is mounted on the ball 3. Unlike deep groove ball bearings, it is not necessary to use separators 4B having different shapes, and separators 4 having the same shape are used. As in the case of the deep groove ball bearing, when the number of balls 3 is an odd number, two balls 3 to which the separators 4 are mounted are arranged at one place in the row of balls 3.

  The separator 4 used for the angular ball bearing preferably has a shape as shown in FIG. That is, one of the flat surfaces where the through-hole 4a of the substantially plate-like separator 4 opens is an inclined surface 4b inclined in a direction perpendicular to a straight line connecting the bottoms 5a and 5a of the two recesses 5 and 5. Thus, the thickness of the separator 4 is gradually changed along the direction. As shown in FIGS. 6 and 7, the thicker side of the separator 4 is arranged on the counter bore side in the bearing central axis direction.

  In such a separator 4, since the thicker side of the separator 4 interferes with the outer ring 2, the separator 4 does not rotate around the ball 3 in the through hole 4 a. Since the ball 3 is fitted in the recess 5, the separator 4 is less likely to rotate, but the separator 4 is less likely to rotate due to the interference. As a result, the contact between the separator 4 and the ball 3 is surely generated in the concave portion 5, so that the contact surface pressure is stably kept low.

In the first to third embodiments described above, the type of solid lubricant constituting the separator 4 is not particularly limited, but at least one of molybdenum disulfide and tungsten disulfide is mixed with metal and sintered. A sintered metal or a composite material composed of at least one of molybdenum disulfide and tungsten disulfide, polytetrafluoroethylene, and polyetheretherketone is preferable. The metal used for sintering may be one kind of metal, but may be a mixture of a plurality of metals or an alloy.
These solid lubricants have excellent lubricity. Moreover, since it is low outgas, it can be used even under high temperatures. For example, a sintered metal can be used at 350 ° C. or higher, and a composite material can be used at 200 ° C. or higher.

〔Example〕
Angular ball bearings having substantially the same configuration as the angular ball bearings of FIGS. 6 to 8 were prepared, and a rotation test was performed to evaluate the performance. As a comparative example, the same evaluation is applied to an angular ball bearing in which a substantially annular separator (similar to the separator incorporated in the bearings of FIGS. 10 and 11) is attached to all balls. Went.
In both the examples and the comparative examples, the inner diameter of the angular ball bearing is 95 mm, the outer diameter of the bearing is 170 mm, the bearing width is 32 mm, and the solid lubricant constituting the separator is a sintered alloy containing tungsten disulfide.

In addition, the content of the rotation test is that the center axis of the bearing is in the vertical direction, an axial load is applied so that the maximum contact surface pressure is 1.3 GPa, and rotation is performed in an environment of vacuum and 80 ° C., and the separator is cracked. The rotation speed that occurs is measured. The rotation of the bearing is reversed every rotation of 180 °, and such forward and reverse rotation is repeated.
The results are shown in the graph of FIG. The angular ball bearings of the examples were less susceptible to cracking in the separator than the angular ball bearings of the comparative examples, and the rotational speed at which the cracks occurred was a high-speed rotation that was twice or more that of the comparative examples.

It is a figure which shows the structure of the deep groove ball bearing which is one Embodiment of the ball bearing which concerns on this invention, and is the longitudinal cross-sectional view fractured | ruptured in the surface parallel to a bearing central axis. It is the fragmentary sectional view fractured | ruptured in the surface perpendicular | vertical to the bearing central axis of the deep groove ball bearing of FIG. It is a figure which shows the structure of the deep groove ball bearing which is another embodiment of the ball bearing which concerns on this invention, and is the longitudinal cross-sectional view fractured | ruptured in the surface parallel to a bearing central axis. It is the fragmentary sectional view fractured | ruptured in the surface perpendicular | vertical to the bearing central axis of the deep groove ball bearing of FIG. It is the top view and sectional drawing of the separator integrated in the deep groove ball bearing of FIG. It is a figure which shows the structure of the angular ball bearing which is another embodiment of the ball bearing which concerns on this invention, and is the longitudinal cross-sectional view fractured | ruptured in the surface parallel to a bearing central axis. It is the fragmentary sectional view fractured | ruptured in the surface perpendicular | vertical to the bearing central axis of the angular ball bearing of FIG. It is the top view and sectional drawing of the separator integrated in the angular ball bearing of FIG. It is a graph which shows the result of having evaluated the rotational speed which a crack produces in the separator integrated in the angular ball bearing. It is a figure which shows the structure of the conventional deep groove ball bearing, and is the longitudinal cross-sectional view fractured | ruptured in the surface parallel to a bearing central axis. It is the fragmentary sectional view fractured | ruptured in the surface perpendicular | vertical to the bearing central axis of the deep groove ball bearing of FIG.

Explanation of symbols

1 Inner ring 2 Outer ring 3 Ball 4 Separator 4a Through hole 4b Inclined surface 5 Recess 5a Bottom

Claims (4)

In a ball bearing comprising an inner ring, an outer ring, a plurality of balls arranged to freely roll between the inner ring and the outer ring, and a separator made of a solid lubricant that keeps an interval between the balls,
The separator has a through hole that accommodates the ball, and the plurality of balls arranged in a circle are arranged in every other through hole of the separator,
A ball bearing characterized in that a bearing outer diameter D, a bearing inner diameter d, and a bearing width B satisfy the following two expressions.
0.60 <B / {(D−d) / 2} <1.2
0.39 <(D−d) / 2 / d <0.91   Arc-shaped recesses facing the adjacent balls on both sides are formed on the outer periphery of the separator, and the radius of curvature of the recess is larger than the radius of the balls, and the distance between the bottoms of the two recesses and the The ball according to claim 1, wherein a value obtained by summing a product of the number of separators and a product of the diameter of the balls and the number of balls is 80% or more of a pitch diameter of the ball set. bearing.   In addition to being an angular ball bearing, one of both planes where the through hole of the substantially plate-like separator opens is an inclined surface that is inclined in a direction perpendicular to a straight line connecting the bottoms of the two recesses. The ball bearing according to claim 1 or 2, wherein the separator having the larger thickness side is disposed on the counterbore side.   The solid lubricant is a sintered metal obtained by mixing and sintering at least one of molybdenum disulfide and tungsten disulfide with a metal, or at least one of molybdenum disulfide and tungsten disulfide, polytetrafluoroethylene, and polyether ether. The ball bearing according to claim 1, wherein the ball bearing is a composite material made of ketone.