JP2014194283A - Ball bearing, carrier device and carrier robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball bearing which hardly causes the locking due to the biting of a separator.SOLUTION: A ball bearing includes: an inner ring; an outer ring; a plurality of balls arranged freely rollably between the inner ring and the outer ring; and an annular retainer along the inner ring and the outer ring. Therein, the balls are provided in a pocket which retains the balls in the retainer, and separators are provided in the pocket which retains the separators of solid lubricant in the retainer arranged between adjacent two balls. The separators are cylindrical-shaped members of which both edge surfaces (both bottom surfaces of a column) are confronted with the balls. Diameter b of the ball, diameter d of the separator and the total amount t of gaps between the balls and the separators in the circumferential direction satisfy the following relations: 0.6b≤d≤0.95b, 0.3b≤t≤2b.

Description

  The present invention relates to a ball bearing including a plurality of separators made of a solid lubricant between balls arranged in a track, and a transfer device and a transfer robot including the ball bearing.

  2. Description of the Related Art Conventionally, liquid crystal panel transfer devices and transfer robots are sometimes used in a vacuum environment, and bearings used for the transfer devices and transfer robots are also vacuum specifications. For example, fluorine grease that is low outgas or solid lubricant that is low outgas is used as a bearing lubricant. A solid lubricant is a self-lubricating material containing a solid lubricant, which forms a solid lubricant film by sliding to the counterpart by sliding with a rolling element or raceway surface, and this film contributes to lubrication. A ball bearing is used in which a cylindrical separator (also referred to as a spacing member or a spacer) is disposed between balls.

  However, in the ball bearing having the separator as described above, the separator is caught between the inner and outer rings during rotation (so-called wedge effect) due to ball clogging due to the advance and delay of the ball, and the rotation stops (hereinafter referred to as “lock”). There is a problem that there is a risk of ”.

  As prior arts for improving this portion, there are those disclosed in Patent Documents 1 to 4, and a ball bearing including a columnar separator made of a solid lubricant is disclosed. And the bearing structure for loading a separator inside a bearing, the shape and dimension of a separator, the holding structure of a separator, etc. are described.

  Patent Document 1 describes a ball bearing in which the dimension in the longitudinal direction of a cylindrical separator is limited to 1.3 to 2.0 times the ball diameter. Patent Document 2 describes a ball bearing using a spherical separator having a smaller diameter than a ball and a cylindrical separator in combination. Patent Document 3 describes a ball bearing in which both end surfaces of a separator are formed so that the shape of a projection surface viewed from the axial direction of the bearing is a trapezoid. Patent Document 4 describes a ball bearing that limits the diameter of a cylindrical separator, the length of the separator, and the groove radius of the inner and outer rings.

  In the inventions described in these Patent Documents 1 to 4, even when the number of separators arranged in the track is large, locking due to the biting of the separators hardly occurs, and smooth rotation can be maintained over a long period of time. It is to provide ball bearings.

JP 2006-022864 A JP 2006-017241 A JP 2006-009935 A JP 2008-267401 A

  However, these prior arts limit the size or shape of the separator to alleviate the increase in torque caused by clogging and suppress the occurrence of locks. It is not something to prevent.

  Here, the ball clogging phenomenon of the ball bearing will be described. The ball clogging phenomenon is one of the behaviors of a bearing that is likely to occur in a ball bearing with a total ball configuration. When the bearing is rotated, the balls are concentrated locally in the ball row of the bearing, and the inner and outer rings are connected via a plurality of balls. This is a phenomenon in which the ball is clogged so as to spread and the rotation is locked. This is because a ball and a ball adjacent to each other compete at the time of rotation of the bearing, so that one of them is pressed against the inner ring and the other is pressed against the outer ring, and the bearing rotation is locked. Even if the member adjacent to the ball is not a ball but a cylindrical separator, if the state where the ball and the separator are locally concentrated can occur, the ball as described above regardless of the shape of the adjacent member The clogging phenomenon occurs in principle.

  Therefore, with the bearing configuration described in Patent Literatures 1 to 4, even if the size and shape of the solid lubricant separator are controlled to a certain set value, the ball and the adjacent member are restricted from being concentrated. There was a problem that it was not effective in preventing the occurrence of the clogging phenomenon.

  An object of the present invention is to provide a ball bearing, a transport device, and a transport robot that are less likely to be locked due to biting of the separator by preventing occurrence of clogging of the solid lubricant separator.

In order to solve the above-described problem, a ball bearing according to the present invention includes an inner ring, an outer ring, a plurality of balls that are freely rollable between the inner ring and the outer ring, and two adjacent balls. A ball bearing comprising: a solid lubricant separator disposed on the inner ring; and a retainer having an annular shape along the inner ring and the outer ring and having a pocket for holding the separator and a pocket for holding the ball. The pockets holding the holes communicate with each other in an area corresponding to at least three of the balls,
The separator has a cylindrical shape and slides with both end surfaces facing the ball, and the side surface and the corner of the separator slide with the inner ring raceway surface or the outer ring raceway surface, and the ball diameter b and the separator diameter d. The diameter D of the pocket holding the separator and the total clearance t in the circumferential direction of the ball and the separator satisfy the following formula, thereby restricting the clogging phenomenon and avoiding the concentrated state of the ball and the separator. Therefore, the separator is less likely to be locked by biting.
0.6D ≦ d ≦ 0.95D
0.3b ≦ t ≦ 2b

Here, in the ball bearing, when the diameter of the ball is b and the number of the balls is bn, the clearance amount in the region corresponding to the three balls is set to 3 × 0.3 b / bn or more. It is preferable.
Moreover, in order to solve the said problem, the conveying apparatus which concerns on this invention was provided with the said ball bearing.
In order to solve the above problem, a transfer robot according to the present invention includes the ball bearing.

  Since the total circumferential clearance t and the solid lubricant separator diameter d are appropriate values, a ball bearing, a transport device, and a transport robot that suppress the occurrence of a clogging phenomenon and are less likely to be locked due to the biting of the separator. There is an effect that can be provided.

It is sectional drawing of the planar direction of the ball bearing in 1st Embodiment. It is a top view of the ball bearing which shows a 1st embodiment. It is a fragmentary sectional view of the ball bearing explaining the phenomenon that a bearing locks by biting of a separator. It is explanatory drawing of the test method which evaluated this invention. It is a part of sectional drawing of the plane direction of the ball bearing in 2nd Embodiment. It is sectional drawing of the radial direction cut | disconnected by the AA position of FIG. It is sectional drawing of the radial direction of the ball bearing in 3rd Embodiment (inner ring side arrangement | positioning). It is sectional drawing of the radial direction of the ball bearing in 3rd Embodiment (outer ring side arrangement | positioning). It is sectional drawing (a) of the planar direction of the ball bearing in 4th Embodiment, and sectional drawing (b) of radial direction of AA position (inner ring side arrangement | positioning). It is sectional drawing (a) of the planar direction of the ball bearing in 4th Embodiment, and sectional drawing (b) of the radial direction of an AA position (outer ring side arrangement).

FIG. 1 is a sectional view of a ball bearing in the first embodiment, and FIG. 2 is a plan view of the ball bearing. The bearing is a deep groove ball bearing, and can freely roll between the inner ring 1 having the inner ring raceway surface 11 on the outer peripheral surface, the outer ring 2 having the outer ring raceway surface 21 on the inner peripheral surface, and the inner ring raceway surface 11 and the outer ring raceway surface 21. And a plurality of separators 6 made of a solid lubricant that keeps the distance between the balls. The separator 6 is a columnar member, and both end surfaces (both bottom surfaces of the column) are opposed to the ball. Further, the ball diameter b, the separator diameter d, and the total clearance t in the circumferential direction of the ball and separator satisfy the following formula.
0.6b ≦ d ≦ 0.95b
0.3b ≦ t ≦ 2b

  As shown in FIG. 2, a groove 7 is provided on the side surfaces of the inner and outer rings 1 and 2 for loading a solid lubricant separator. When the grooves in the inner and outer rings are arranged in the same phase, the grooves communicate with the raceway surface and are opened. It functions as a rectangular insertion hole. A cylindrical solid lubricant separator 6 is loaded into the bearing through this hole. The solid lubricant separator 6 is loaded while being fed one after another by sliding the ball 3 in the track so as to be disposed between the balls 3 previously placed between the inner and outer rings 1 and 2.

In the deep groove ball bearing according to the above formula, the separator 6 is not easily caught between the inner and outer rings 1 and 2, so that the lock is less likely to occur. Further, the separator 6 is formed of a low outgassing solid lubricant, and the deep groove ball bearing is lubricated with the solid lubricant transferred from the separator 6, so that the outgas is low.
Therefore, it can be suitably used even in a vacuum environment. Further, the transition of the solid lubricant occurs immediately after the start of the rotation of the deep groove ball bearing. Usually, at least one of the outer ring, the inner ring and the ball is coated with a solid lubricant for initial lubrication.

  By the way, in order to regulate the ball clogging phenomenon, a structure that avoids the concentrated state is necessary, but the reason why the concentrated state hardly occurs stochastically in the deep groove ball bearing of this embodiment will be described.

  Here, when the diameter of the ball 3 is b, the diameter of the separator 6 is d, and the total clearance t in the circumferential direction of the ball 3 and the separator 6 is, the larger the circumferential clearance t is, the less the concentrated state is generated. If the circumferential clearance t is too large, the solid lubricant separator 6 may collide with the ball 3 when the bearing rotational speed changes, and the solid lubricant separator 6 may be cracked or chipped. If t exceeds twice the ball diameter (= 2b), the possibility increases. Therefore, an upper limit value is set so that t does not exceed 2b (t ≦ 2b).

  Furthermore, in order for the solid lubricant separator 6 having a cylindrical shape to smoothly move relative to the tunnel formed by the inner and outer ring raceway surfaces 11 and 21 without being caught, it is necessary to regulate the diameter of the separator 6. As described above, since the allowable value of the circumferential clearance t is set relatively large (t ≦ 2b), the solid lubricant separator 6 between the balls has a degree of freedom with respect to the circumferential direction. It is high and a state of free play in the above-described tunnel occurs during bearing rotation.

  At that time, as shown in FIG. 3, the solid lubricant separator 6 rises in the tunnel, and the corner of one end contacts the inner ring raceway surface 11 and the corner of the other end contacts the outer ring raceway surface 21. When the bearing is further raised by the rotation of the bearing, the inner and outer rings are locked via the solid lubricant separator 6.

  In order to prevent this, it is necessary to make the diameter of the tunnel, that is, the ball diameter b and the solid lubricant separator diameter d as close as possible so that the solid lubricant separator 6 rises in the tunnel. However, since there is an influence of the arcs of the inner and outer rings 1 and 2 and d = b, the bearing cannot be loaded into the bearing, so the maximum value of d is 0.95b (d ≦ 0.95b).

  On the other hand, even if d is too small, the solid lubricant separator may fall off from the tunnel opening between the inner and outer ring raceway surfaces, so the lower limit is set to 0.6b (0.6b ≦ d). If it is 0.6b, the solid lubricant separator 6 will not fall out of the tunnel opening between the inner and outer ring raceway surfaces.

  Further, in the configuration of FIG. 2, the solid lubricant separator 6 can come into contact with all the balls 3, so that the transfer (transfer) of the solid lubricant from the solid lubricant separator 6 is performed reliably, The ball is reliably lubricated. Thus, it is desirable that a solid lubricant separator be disposed between all balls, but the bearing can be lubricated if at least one solid lubricant separator is present in the bearing.

  In that case, since it is possible to load a larger number of balls as the solid lubricant separator 6 is smaller, for example, a larger load can be applied to a bearing of the same size. However, since the number of the solid lubricant separators 6 becomes smaller, the bearing life (lubricating life) due to the exhaustion of the lubricant is shortened.

  Except that the type of the bearing is an angular ball bearing, a ball bearing having substantially the same configuration as that of the ball bearing of this embodiment was prepared, a rotation test was performed, and the validity of the numerical value of the formula was evaluated. The solid lubricant separator is all installed between the balls.

  In the simple apparatus shown in FIG. 4, the ball bearing end face is installed on the base 93 and the inner ring 1 is loaded with an appropriate axial load by the weight 91 mounted on the hand-turning jig 92, and all the balls are loaded. The bearing was rotated while contacting both the inner and outer rings 1 and 2. The test method was to measure how many times clogging occurred during 100 rotations by rotating the bearing in one direction for 100 rotations by a hand turning jig 92 of the bearing inner ring shaft at a rotation speed of 6 rotations per minute.

  As a result of a comparative test using three types of samples in which the diameter d of the solid lubricant separator is 0.96 times, 0.95 times, and 0.90 times the ball diameter b, 0.96b was locked 10 times. On the other hand, 0.95b and 0.90b did not lock once. From this, it is understood that clogging does not occur when d ≦ 0.95b. On the other hand, if d is 0.6b or more, the solid lubricant separator does not fall off from the tunnel opening between the inner and outer ring raceway surfaces.

  In this test, the length of the solid lubricant separator is the same as the ball diameter b, and the solid lubricant separator when d = 0.69b can be loaded from the insertion hole between the inner and outer rings of the bearing during assembly. A certain inner ring outer diameter and outer ring inner diameter are selected.

  Next, as a result of a comparative test using three types of samples in which the total clearance t in the circumferential direction of the ball and the separator is 0.2 times, 0.3 times, and 0.4 times the ball diameter b, 0.2b is 20 times. While locking occurred, 0.3b and 0.4b did not lock even once. From this, it can be seen that clogging does not occur if t ≧ 0.3b.

  On the other hand, if t does not exceed 2b, even if the solid lubricant separator collides with the ball when the rotation speed of the bearing is changed, there is a low possibility that the solid lubricant separator will be cracked or chipped. In this test, the diameter of the solid lubricant separator is d = 0.8b, which is sufficiently away from the clogging condition.

  FIG. 5 is a cross-sectional view of the ball bearing in the second embodiment, and FIG. 6 is a cross-sectional view taken along the line AA of FIG. The deep groove ball bearing of the present embodiment rolls between an inner ring 1 having an inner ring raceway surface 11 on an outer peripheral surface, an outer ring 2 having an outer ring raceway surface 21 on an inner peripheral surface, and an inner ring raceway surface 11 and an outer ring raceway surface 21. A plurality of balls 3 arranged freely and an annular retainer 4 along the inner ring 1 and the outer ring 2 are provided, and a pocket 41 is provided in a column portion 42 of the retainer 4. And a separator 5 made of a solid lubricant disposed between the two balls.

The separator 5 is cylindrical and has both end surfaces facing the ball 3, and the ball diameter b, the separator diameter d, the pocket diameter D, and the total clearance t in the circumferential direction of the ball and the separator are expressed by the following equations. Satisfied.
0.6D ≦ d ≦ 0.95D
0.3b ≦ t ≦ 2b

  As shown in FIG. 6, a pocket 41 for the solid lubricant separator 5 is provided in a column portion 42 (a portion between the balls) of the cage 4, and a part of the pocket 41 is formed on the inner ring side and the outer ring. Open to the side. The solid lubricant separator 5 is built in the pocket 41, the end surface portion of the solid lubricant separator 5 slides facing the ball, and the side and corners of the solid lubricant separator 5 are the inner ring raceway surface 11 and the outer ring raceway. It is configured to slide with the surface 21.

  By this sliding, the solid lubricant is transferred to the mating member and lubricates the bearing. In this embodiment, the lubrication performance is improved by arranging the pockets 41 at two locations near the contact angle between the inner ring raceway surface 11 and the ball 3 and near the contact angle between the outer ring raceway surface 21 and the ball 3.

In the case of a ball bearing having the cage 4, the pocket diameter D is considered to be a structure that functions similarly to the tunnel diameter (corresponding to the ball diameter b) of the inner and outer ring raceway surfaces 11 and 21 in the first embodiment. By replacing the ball diameter b in the conditional expression of the first embodiment with the pocket diameter D, the following expression is established with respect to the diameter d of the solid lubricant separator.
0.6D ≦ d ≦ 0.95D

Further, since the cage is present, the balls and the separator do not concentrate at one place, but a partial concentration state occurs. The pockets of the cage communicate with each other in an area corresponding to at least three balls, and the total amount of circumferential clearance t is given by the following formula, where the number of balls is bn and the ball diameter is b.
3 × 0.3b / bn ≦ 3 × t / bn ≦ 3 × 2b / bn
Organizing the formula gives the following formula.
0.3b ≦ t ≦ 2b

Therefore, in the case of a ball bearing having a cage, a ball bearing that does not cause clogging can be obtained if the following formula is satisfied.
0.6D ≦ d ≦ 0.95D
0.3b ≦ t ≦ 2b

  7 and 8 are radial cross-sectional views of the ball bearing in the third embodiment. The ball bearing of this embodiment is substantially the same as the ball bearing of the second embodiment, but the number of pockets 41 provided in the retainer column 42 is different. In the present embodiment, the pocket 41 is disposed at one place on the inner ring side or the outer ring side of the retainer column 42.

  The end face portion of the solid lubricant separator 5 slides facing the ball 3, and the side and corners of the solid lubricant separator slide with the inner ring raceway surface 11 or the outer ring raceway surface 21, so that the solid lubricant becomes the counterpart member. However, the lubricant can be transferred to the entire interior of the bearing by the skew movement of the ball 3. Therefore, even if the number of pockets 41 is small and the number of solid lubricant separators 5 is small, the bearing can be lubricated.

  9 and 10 are a sectional view (a) in the plane direction and a sectional view (b) in the radial direction of the ball bearing in the fourth embodiment. The ball bearing of this embodiment is substantially the same as the ball bearing of the third embodiment, but the thickness of the solid lubricant separator 5 is different. In this embodiment, the thickness of the solid lubricant separator is extremely thin compared to its diameter d.

  Even if the solid lubricant separator has a disk shape such as a 10-yen coin, a bearing can be configured by using the cage 4 having the pocket 41 for the solid lubricant separator as shown in FIGS. is there. At this time, if the bearing is manufactured in accordance with the conditions of claim 2 of the present application, a bearing that does not cause clogging can be obtained even if the solid lubricant separator has a disk shape.

  The ball bearing of the present invention can be suitably applied to a transfer device or a transfer robot used in a vacuum environment.

1 Inner ring 2 Outer ring 3 Ball 4 Cage 5 Separator (with cage)
6 Separator (without cage)
7 Groove 11 Inner ring raceway surface 21 Outer ring raceway surface 41 Retainer pocket 42 Retainer column 91 Weight t Total clearance in the circumferential direction

Claims (4)

An inner ring, an outer ring, a plurality of balls that are freely rollable between the inner ring and the outer ring, a solid lubricant separator that is disposed between two adjacent balls, the inner ring, and the In a ball bearing comprising an annular shape along an outer ring, and a cage having a pocket for holding the separator and a pocket for holding the ball,
The pockets holding the separator communicate with each other in an area corresponding to at least three of the balls;
The separator has a cylindrical shape and slides with both end surfaces facing the ball, and the side surface and the corner of the separator slide with the inner ring raceway surface or the outer ring raceway surface, and the ball diameter b and the separator diameter d. A ball bearing characterized in that the diameter D of the pocket holding the separator and the total clearance t in the circumferential direction of the ball and the separator satisfy the following formula.
0.6D ≦ d ≦ 0.95D
0.3b ≦ t ≦ 2b   2. The ball bearing according to claim 1, wherein when the diameter of the ball is b and the number of the balls is bn, a clearance amount in a region corresponding to the three balls is set to 3 × 0.3 b / bn or more.   A conveying apparatus comprising the ball bearing according to claim 1.   A transfer robot comprising the ball bearing according to claim 1.

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