CN112739923A

CN112739923A - Retainer for ball bearing and rolling bearing

Info

Publication number: CN112739923A
Application number: CN201980061278.0A
Authority: CN
Inventors: 石田光; 辻直明; 伊藤千春; 小畑智彦
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2018-09-21
Filing date: 2019-09-19
Publication date: 2021-04-30
Anticipated expiration: 2039-09-19
Also published as: JP2020159548A; CN112739923B; DE112019004733T5

Abstract

The retainer (6) for a ball bearing has 2 annular bodies (10, 10) made of synthetic resin and overlapped with each other in the axial direction. Each annular body (10) has: a plurality of half-ball-shaped pocket wall parts (13) which are arranged at a predetermined interval in the circumferential direction and which respectively constitute inner wall surfaces of pockets for holding balls; and a plurality of web sections (14) that connect circumferentially adjacent pocket wall sections (13) to each other, wherein 2 annular bodies (10, 10) are connected by overlapping the web sections (14) with each other, and wherein a cutout section (7) is provided on the inner or outer diameter surface of the pocket wall section (13) such that the width of the radial dimension of the pocket wall section (13) is smaller than the radial dimension of the web sections (14).

Description

Retainer for ball bearing and rolling bearing

RELATED APPLICATIONS

The application requires the application with the application date of 2018, 9 and 21 and the application number of JP special application 2018-177772; the priority of the application with application date of 2019, 3 and 22 and application number of JP application 2019-.

Technical Field

The present invention relates to a cage for a ball bearing and a rolling bearing, and more particularly, to a technique for increasing the speed of a rolling bearing for a machine tool spindle, a motor, or the like and prolonging the life of grease.

Background

A synthetic resin cage for a ball bearing has been proposed (patent document 1). As shown in fig. 36, the synthetic resin cage has hemispherical pockets 50 formed at equal intervals in the circumferential direction, and a connecting plate portion 51 between the pockets 50 has connecting holes 52 and connecting claws 53 that engage with each other. The synthetic resin retainer engages the two

annular bodies

54, 54 having the same shape by engaging the connection claws 53 with the connection holes 52.

As another ball bearing cage, an iron plate wave cage has been proposed (patent document 2). As shown in fig. 37, in order to reduce friction loss with the balls 56, the iron plate wave cage 55 is formed with through holes 58 penetrating in the axial direction in the pocket portion 57.

As another ball bearing cage, as shown in fig. 39, a technique has been proposed in which an inner circumferential surface 63 of a circumferential portion of an iron plate wave cage where each pocket 62 is located is formed in a shape recessed toward an outer radial side (patent document 3).

Documents of the prior art

Patent document

Patent document 1: JP patent publication 2013-007468

Patent document 2: JP patent publication No. 2018-071720

Patent document 3: JP 2010-065816 publication

Patent document 4: JP 2007-285506 publication

Disclosure of Invention

Problems to be solved by the invention

As shown in fig. 38, the conventional wave cage made of synthetic resin has the following shape: the width H1 of the pocket portion 59 is 40% to 50% of the ball diameter Bd, centering on the pitch circle PCD of the ball 60, and holds the ball 60. The pocket portion 59 has a width H1 of 70% to 80% of the radial dimension between the outer ring inner diameter and the inner ring outer diameter.

When the region dn rotates at a high speed of 60 ten thousand or more, the grease moves from the movement space to the static space Sa and is held in the static space Sa. Therefore, it is difficult to supply grease to the rolling surface, and insufficient lubrication supply causes heat generation and a problem of shortened lubrication life. Here, "dn" refers to a value of an inner diameter (mm) of the bearing multiplied by a rotation speed (rpm). Further, in the width H1 of the pocket portion 59, the shearing resistance of the grease between the balls 60 and the pocket and between the cage back surface and the seal is high, and there is a problem of large torque or heat generation.

In addition, in the conventional wave cage (fig. 36) made of synthetic resin, the axial clearance between the balls and the inner diameter edges of the pockets 50 of the cage is wide. Therefore, the grease adhering to the surface of the ball is less scraped off in the portion of the pocket 50, and more scraped off in the vicinity of the inner diameter edge of the web portion 51 between the pocket 50 and the pocket 50. Since the scraped grease is scattered on the outer ring rolling surface by centrifugal force, it takes time to discharge the grease from the movement space to the static space, and it takes time to accommodate the grease.

When the bearing is assembled, the grease sealed in the vicinity of the cage pockets is stirred in the movement space by the operation of the bearing and adheres to the surfaces of the balls and the like. In this case, the grease on the ball surface is scraped off by the retainer, and the scraped grease is discharged from the vicinity of the rolling surface as a movement space to the static space Sa such as between the retainer 59 and the seal plate 62, fig. 38). By being discharged to some extent into the static space Sa, the grease inside the bearing becomes compliant. Thereafter, the base oil of the grease in the static space Sa is gradually supplied to the rolling surfaces, and the bearing is lubricated in a slight amount with less heat generation. As described above, before the grease adhering to the balls 60 is adapted to move to the static space Sa, the grease generates a large amount of heat due to the stirring resistance, and therefore, it is desired to perform the adaptation in advance.

In the iron plate wave holder 55 shown in fig. 37, since the through hole 58 is formed, there is a fear that the strength is insufficient. In the wave cage of the iron plate shown in fig. 39, the iron plate must be punched and formed by pressing to produce two ring-shaped members, which increases the production cost.

The invention aims to provide a retainer for a ball bearing and a rolling bearing, which aim to increase the speed of the rolling bearing and prolong the service life of grease, shorten the adaptation time of the grease and have excellent productivity.

Means for solving the problems

The retainer for a ball bearing of the present invention has 2 annular bodies made of synthetic resin which are overlapped with each other in an axial direction, each annular body having: a plurality of half-ball-shaped pocket wall portions arranged at predetermined intervals in a circumferential direction and each constituting an inner wall surface of a pocket for holding balls; a plurality of web portions that connect the pocket wall portions adjacent to each other in the circumferential direction, the 2 annular bodies being connected by the respective web portions overlapping each other, characterized in that:

the pocket wall portion has a cutout portion on an inner diameter surface or an outer diameter surface thereof so that a width of the pocket wall portion in a radial direction is smaller than a radial direction of the connecting plate portion.

According to this aspect, the pocket wall portion is provided with the cutout portion on the inner diameter surface or the outer diameter surface thereof so that the width of the pocket wall portion is smaller than the radial dimension of the connecting plate portion. Therefore, when the bearing is operated, the grease accumulated in the stationary space is supplied from the cutout portion to the rolling surface by a centrifugal force. That is, by scraping a part of the grease which is to be retained in the stationary space at the cutout portion, the base oil of the grease is separated and easily supplied from the cutout portion to the inside of the retainer, the surface of the ball, and the rolling surface in this order. This can suppress heat generation of the ball bearing, and can prolong the life of the grease as compared with the conventional art. Further, since the cutout portion is provided in the pocket wall portion, grease shearing resistance between the ball and the pocket can be reduced, and torque and heat generation of the ball bearing can be reduced.

Further, by providing the notch portion at the start of operation, the amount of grease adhering to the ball surface to be scraped is increased. Thus, the grease can be easily discharged from the space to the stationary space, and the adaptation time of the grease can be shortened. Since the notch can be easily formed by a die or the like, the manufacturing cost can be reduced as compared with the conventional technique of machining a recess in a corrugated retainer made of a steel plate, and a retainer for a ball bearing having excellent productivity can be manufactured. Here, the "dead space" refers to a space in which the rolling elements and the cage do not pass through when the bearing rotates in a bearing space enclosed by the inner ring, the outer ring, and the seal plate.

In the present invention, the position of the deepest portion of the cutout portion in the bearing radial direction may be located in the vicinity of the pitch circle of the balls. When the deepest portion of the cutout portion reaches the vicinity of the radial position in the vicinity of the pitch circle of the ball, the cutout portion opens at a portion where the clearance between the ball and the inner surface of the pocket wall portion is narrow, and grease can be scraped off more at a portion near the stationary space. Therefore, the grease can be easily discharged from the movement space, and the adaptation time of the grease can be further shortened.

In the present invention, the cutout portion may be located on an outer diameter side of the pocket wall portion, and a flange portion may be provided to protrude in an axial direction from an outer diameter edge of the connecting plate portion. By providing the flange portion, the grease scraped off in the vicinity of the connection portion where the pocket wall portion and the connecting plate portion are connected is scattered by the centrifugal force. This prevents the grease from being drawn into the outer race rolling surface which becomes the movement space, and further shortens the time for discharging the grease from the movement space to the static space.

In the present invention, the cutout portion may be a curved shape in which an inner diameter surface or an outer diameter surface of the pocket wall portion is a concave curve as viewed in the axial direction of the bearing. In this case, local stress concentration can be prevented from acting on the notch portion of the pocket wall portion. Further, the notch portion can be easily formed by a mold or the like.

In the present invention, the pocket wall portion may have a thick portion whose thickness in the bearing axial direction is increased by the amount of volume reduction caused by the cutout portion. Since the pocket wall portion has the thick portion, a decrease in rigidity of the ball bearing retainer due to the notch portion can be suppressed.

In the present invention, the dimension in the axial direction of the two overlapped web portions may be 55% to 65% of the diameter of the ball. Here, "55% to 65%" means more than 55% and less than 65% of the diameter of the ball. According to this configuration, the ball bearing cage has high rigidity, and resonance with the rotational speed does not occur due to the natural frequency of the ball bearing cage being increased. Therefore, vibration of the ball bearing retainer due to resonance is not generated, temperature rise is suppressed, and stable rotation is obtained. In this case, the resonance point is shifted by limiting only the axial dimension of the connecting plate portion, and thereby temperature rise is suppressed and stable rotation is obtained. Therefore, the cost can be reduced as compared with the case where the rigidity of the retainer is increased by using a metal member or the like.

The rolling bearing of the present invention has the ball bearing retainer described above. Therefore, the ball bearing cage according to the present invention can obtain the above-described effects.

In the rolling bearing of the present invention, the balls may be ceramic balls. In this case, for example, the specific gravity can be made smaller than that of steel balls made of bearing steel or the like, so that the bearing can be speeded up and the heat resistance can be improved.

Any combination of at least two structures disclosed in the claims and/or in the description and/or in the drawings is comprised in the present invention. In particular, any combination of two or more of each of the claims is encompassed by the present invention.

Drawings

Fig. 1 is a sectional view of a rolling bearing having a ball bearing cage according to embodiment 1 of the present invention;

fig. 2A is a perspective view of the ball bearing retainer;

fig. 2B is a perspective view for explaining a thick portion of the ball bearing retainer;

fig. 3 is a front view of the ball bearing retainer as viewed from the axial direction;

fig. 4A is an enlarged cross-sectional view of the ball bearing retainer;

FIG. 4B is a cross-sectional view taken along line IVB-IVB in FIG. 4A;

fig. 5 is a front view of the ball bearing retainer in a state where balls and an outer ring are combined;

FIG. 6 is a partial cross-sectional view taken along line VI-VI in FIG. 5;

FIG. 7A is an explanatory diagram showing the results of grease flow analysis of the ball bearing cage;

FIG. 7B is an explanatory diagram showing the results of a grease flow analysis of a conventional ball bearing cage;

FIG. 8 is a graph showing the results of a grease suitability test for the product according to this embodiment and a conventional cage;

FIG. 9 is a graph showing the results of another grease suitability verification test for each embodiment product and a conventional cage;

fig. 10 is a front view of a ball bearing cage according to embodiment 2 of the present invention;

FIG. 11 is a partial side view of the ball bearing retainer as viewed from the inner diameter side;

fig. 12 is an enlarged cross-sectional view showing a connecting plate portion of the ball bearing retainer;

fig. 13 is a front view of the ball bearing retainer in a state in which balls and an outer race are combined;

FIG. 14 is a partial cross-sectional view taken along line XIV-XIV in FIG. 13;

fig. 15 is a perspective view of a ball bearing retainer according to embodiment 3 of the present invention;

fig. 16 is a front view of the ball bearing retainer as viewed from the axial direction;

FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. 16;

fig. 18 is a perspective view of a ball bearing retainer according to embodiment 4 of the present invention;

fig. 19 is a front view of the ball bearing retainer as viewed from the axial direction;

FIG. 20 is a cross-sectional view taken along line XX-XX in FIG. 19;

fig. 21 is a perspective view of a ball bearing retainer according to embodiment 5 of the present invention;

fig. 22 is a front view of the ball bearing retainer as viewed from the axial direction;

fig. 23 is a sectional view taken along line XXIII-XXIII of fig. 22;

fig. 24 is a perspective view of a ball bearing retainer according to embodiment 6 of the present invention;

fig. 25 is a front view of the ball bearing retainer as viewed from the axial direction;

fig. 26 is a sectional view taken along line XXVI-XXVI in fig. 25;

fig. 27 is a sectional view of a rolling bearing having a ball bearing cage according to embodiment 7 of the present invention;

fig. 28 is a perspective view of a ball bearing retainer according to embodiment 8 of the present invention;

fig. 29 is a sectional view of a rolling bearing having the ball bearing retainer;

FIG. 30 is a schematic view of a high-speed testing machine;

fig. 31 is a view showing the results of a temperature rise test of the ball bearing retainer;

FIG. 32 is a graph showing the results of a temperature rise test of a conventional product;

fig. 33 is a front view of a ball bearing retainer according to an embodiment of a 1 st modified example of the shape of a cutout portion of the present invention;

fig. 34 is a front view of a ball bearing retainer according to an embodiment of a 2 nd modified example of the shape of the cutout portion of the present invention;

fig. 35 is a front view of a ball bearing retainer according to an embodiment of a 3 rd modified example of another shape of a cutout portion according to the present invention;

fig. 36 is a perspective view of a synthetic resin cage according to the prior art;

fig. 37 is a perspective view of a prior art iron plate wave cage;

fig. 38 is a sectional view of a rolling bearing of the prior art;

fig. 39 is a partially enlarged perspective view showing a part of a conventional iron plate wave cage.

Detailed Description

[ embodiment 1 ]

A ball bearing cage and a rolling bearing according to embodiment 1 of the present invention will be described with reference to fig. 1 to 9.

< Rolling bearing >

As shown in fig. 1, the rolling bearing 1 is a deep groove ball bearing, and includes an inner ring 2, an outer ring 3, a plurality of balls 5 provided between rolling

surfaces

2a, 3a of the inner and

outer rings

2, 3, a ball bearing retainer 6 for retaining the balls 5, and a seal plate 4 as a non-contact seal. The balls 5 are steel balls or ceramic balls.

An annular bearing space is formed between the outer periphery of the inner ring 2 and the inner periphery of the outer ring 3, and openings at both ends in the axial direction of the annular bearing space are closed by

seal plates

4, 4. Grease for lubrication is sealed in the closed bearing space. An outer ring seal groove is formed in the inner peripheral surface of the outer ring 3, and an inner ring seal groove is formed in the outer peripheral surface of the inner ring 2. The sealing plate 4 is formed of a steel plate and has a circular plate shape. The outer end of the sealing plate 4 is arranged in the outer ring sealing groove. The inner end of the seal plate 4 is inserted into the inner ring seal groove with a predetermined gap therebetween, and is not in contact with the inner ring 2.

< ball bearing retainer 6>

As shown in fig. 2A, 2B, and 3, the ball bearing retainer 6 includes two synthetic resin

annular bodies

10, 10 that are stacked in the axial direction. Each annular body 10 is formed by injection molding of a synthetic resin, for example. The two

annular bodies

10, 10 have the same shape and can be molded by the same mold. Examples of the synthetic resin include polyamide (e.g., PA46), polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). In order to improve the strength, glass fibers, carbon fibers, aromatic polyamide fibers, or the like are added to the synthetic resin forming each annular body 10.

As shown in fig. 4A and 4B, each ring body 10 has a plurality of half-ball-shaped pocket wall portions 13 and a plurality of web portions 14. The plurality of half-ball-shaped pocket wall portions 13 are arranged at a constant interval in the circumferential direction, and each constitute an inner wall surface of the pocket portion 12 that holds the ball 5. The plurality of web portions 14 connect circumferentially adjacent pocket wall portions 13 to each other.

< connecting claw 16 and connecting hole 17>

The web portion 14 has a mating surface 15 that comes into surface contact when the two

annular bodies

10, 10 are connected. Near the center of the mating surface 15 of the web portion 14, a connecting claw 16 projecting in the axial direction and a connecting hole 17 into which the connecting claw 16 of the other annular body 10 is inserted are formed. Hook portions 19 are formed at axial distal end portions of the connecting claws 16, and the hook portion 19 of one ring body 10 engages with a step portion 18 formed on an inner surface of the connecting hole 17 of the other ring body 10. By this engagement, the connection claws 16 are prevented from being pulled out of the connection holes 17, and the two

annular bodies

10, 10 are connected to each other.

< projecting wall portion 20 and accommodation recess 21>

The web portion 14 has a protruding wall portion 20 and an accommodation recess 21. The projecting wall portion 20 is provided at one circumferential end of the mating surface 15 of one annular body 10 so as to project in the axial direction. The receiving recess 21 is provided at the other end in the circumferential direction of the mating surface 15 of one annular body 10, and receives the protruding wall portion 20 of the other annular body 10.

The web portion 14 has the protruding wall portion 20 and the receiving recess 21, and thus, when the two

annular bodies

10, 10 are connected, the joining line of the

annular bodies

10, 10 is positioned at a position deviated from the axial center of the pocket portion 12. Thus, when the ball 5 contacts the web 14 due to the lag or lead of the ball 5 during the bearing operation, the ball 5 can be prevented from contacting the position of the mating line of the two

annular bodies

10, 10. Therefore, the balls 5 can be stably held.

In a state where the two

annular bodies

10, 10 are connected, the projecting wall portion 20 and the accommodating recess portion 21 are set to have a size that generates circumferential and

axial gaps

22, 23 between the projecting wall portion 20 and the accommodating recess portion 21. This prevents the protruding wall portion 20 and the accommodation recess 21 from being obstructed by a difference in shrinkage after injection molding of the annular body 10, and the mating surfaces 15 of the web portions 14 of the two

annular bodies

10, 10 can be reliably brought into close contact with each other.

Partially concave ball surfaces 25 along the outer periphery of the balls 5 are formed at both circumferential end portions of each pocket 12. The partially concave ball surface 25 is a partially concave ball surface having a region orthogonal to the pitch circle of the ball 5, and is formed so as to sandwich the ball 5 and face each other in the forward and backward direction in the traveling direction of the ball 5. The curvature radius of the partially concave ball surface 25 is set to be slightly larger than the radius of the ball 5.

< notch 7>

As shown in fig. 2A and 3, the pocket wall portion 13 is provided with a cutout portion 7 on an inner diameter surface thereof. The cut-out portion 7 is provided to facilitate supply of grease from the static space Sa (fig. 1) to the rolling surfaces 2a and 3a (fig. 1). The notch 7 is formed, for example, at the time of injection molding of the annular body 10, but may be formed by additional processing after injection molding. The cutout portion 7 is formed such that a width H1, which is a radial dimension of the pocket wall portion 13, is smaller than a radial dimension H2 (fig. 3) of the connecting plate portion 14. In this embodiment, the inner diameter surface 13a of the pocket wall portion 13 has a concave curved surface shape as viewed in the axial direction of the bearing. The notch 7 is formed in the following manner: the belt width H1 of the circumferential direction middle portion of the pocket wall portion 13 is smallest, and the belt width H1 gradually increases along the curved surface shape from the circumferential direction middle portion toward both circumferential direction sides.

Specifically, as shown in fig. 1, the cutout portion 7 is a curved surface shape of a concave curve formed by partially cutting out an inner diameter surface of the pocket wall portion 13. The width H1 of the pocket wall portion 13 in which the cutouts 7 are formed is controlled to be within 35% or less of the ball diameter around the pitch circle PCD of the balls 5, and is 50% or less of the radial dimension H3 between the outer ring inner diameter and the inner ring outer diameter. By forming the notch 7 in this manner, grease can be easily supplied from the static space Sa to the rolling surfaces 2a and 3 a.

< thick portion >

As shown in fig. 2B, the pocket wall portion 13 has a thick-walled portion 8, and the thickness of the thick-walled portion 8 in the bearing axial direction is increased by an amount corresponding to the volume reduction caused by the cutout portion 7. In this example, the pocket wall portion 13 is formed to be thicker in the entire axial direction of the bearing by an amount of volume reduction than a pocket wall portion (not shown) in which the cutout portion is not formed. In other words, the entire pocket wall portion 13 becomes the thick portion 8. The thick portion 8 can suppress a decrease in rigidity of the ball bearing retainer 6 due to the notch portion 7.

< Effect >

According to the ball bearing cage 6 and the rolling bearing 1 having the ball bearing cage 6 described above, the notch portion 7 (fig. 3) is provided on the inner diameter surface 13a of the pocket wall portion 13 so that the width H1 of the pocket wall portion 13 is smaller than the radial dimension H2 of the connecting plate portion 14. Therefore, during operation of the bearing, the grease accumulated in the stationary space Sa is supplied from the cutout portion 7 to the rolling surfaces 2a and 3a by centrifugal force. That is, by scraping off a part of the grease that is to be retained in the static space Sa by the cutout portion 7, the base oil of the grease is separated and easily supplied from the cutout portion 7 to the inside of the cage, the ball surface, and the rolling

surfaces

2a and 3a in this order. This can suppress heat generation of the rolling bearing 1, and can prolong the life of the grease as compared with the conventional art. Further, since the notch portion 7 is provided in the pocket wall portion 13, the grease shearing resistance between the balls 5 and the pocket 12 is reduced, and the torque and heat generation of the rolling bearing 1 are reduced.

Further, by providing the notch portion 7 at the start of operation, the amount of grease scraped off from the surface of the ball 5 increases, and the grease is easily discharged from the movement space to the static space Sa. This can shorten the adaptation time of grease. Since the notch 7 can be easily formed by a die or the like, the machining cost can be reduced and the productivity of the ball bearing retainer 6 can be improved as compared with the conventional technique in which a recess is machined in a corrugated retainer made of a steel plate.

The inner diameter surface 13a of the pocket wall portion 13 provided with the cutout portion 7 has a concave curved surface shape as viewed in the bearing axial direction. Therefore, local stress concentration can be prevented from acting on the notch portion 7 of the pocket wall portion 13 in advance. Further, the notch 7 can be easily formed by a mold for injection molding or the like.

The radial position of the deepest portion 7a (fig. 3 and 5) of the notch 7 may be located at or near the pitch circle PCD (fig. 1) of the ball 5. When the deepest portion 7a of the notch portion 7 reaches the vicinity of the radial position in the vicinity of the pitch circle PCD of the ball 5, the notch portion 7 opens at a portion where the gap between the ball 5 and the inner surface of the pocket wall portion 13 is narrow, and a large amount of grease can be scraped off at a portion near the static space Sa. Therefore, the grease can be easily discharged from the movement space, and the adaptation time of the grease can be further shortened. When the balls 5 are ceramic balls, the specific gravity thereof is smaller than that of steel balls made of bearing steel, for example, and the bearing can be speeded up and heat resistance can be improved.

< results of grease behavior analysis >)

Fig. 7A and 7B show the behavior analysis results of the grease. Fig. 7A shows an example of the ball bearing retainer 6 having the notch portion 7 according to the embodiment shown in fig. 1 to 6, and fig. 7B shows an example of the ball bearing retainer 55A not having the notch portion 7. The

ball bearing cages

6 and 70 in both figures have the same structure. Corresponding parts are given the same reference numerals. The difference was confirmed in the case of the ball bearing cage 6 (fig. 7A) having the notch portion 7 from the ball bearing cage 55A (fig. 7B) having no notch portion 7 in that the grease G (blackened portion) adhering to the surface was scraped off at the connecting portion 10a between the pocket wall portion 13 and the connecting plate portion 14, and the amount of grease scraped off was large near the center portion (inside the circle indicated by symbol a) of the pocket wall portion 13 in the bearing circumferential direction.

< analytical conditions >)

The ball 5 is positioned at the center of the pocket of the

ball bearing cage

6, 55A, and the grease is disposed on the surface of the ball 5 with a thickness of 1.5 mm. The contact angle of the ball 5 was 0 DEG, and the flow of grease when the ball 5 rotated once at the rotation speed of the inner ring 2 of 600min-1 was determined.

< test (1) for confirming grease suitability >

Fig. 8 shows the test results of the grease suitability test (1). The horizontal axis represents time (min), and the vertical axis represents the temperature (. degree. C.) of the outer ring 3. The grease compatibility is the performance of applying grease to the surface of the ball 5 and allowing the grease to move to a static space when the bearing starts to operate, and can be confirmed by the temperature rise of the bearing due to the stirring resistance of the grease. The rise in the bearing temperature can be confirmed by the outer ring temperature.

The ball bearing retainer 6 having the notch portion 7 (the embodiment shown in fig. 1 to 6) has a low outer ring peak temperature at each rotation speed and requires a short time for temperature stabilization, as compared with the ball bearing retainer 55A not having the notch portion 7. In the ball bearing retainer 6 having the notch 7, the outer ring temperature was the same as that in the oil lubrication at each rotation speed of 30 minutes.

< test conditions >)

Testing machine: horizontal torque testing machine

The test model is as follows: 6312

Rotating speed: 4000. 6000, 8000, 10000min-1

Loading: fr 411N

And (3) testing: at each speed for 30 minutes

Confirming the item: outer ring temperature

< test (2) for confirming grease suitability

Fig. 9 shows the test results of the grease suitability test (2). The ball bearing cage 6 having the cutout portions 7 (the embodiment shown in fig. 1 to 6) has a grease accommodation time shortened by 30% as compared with a member having no cutout portions. In the case of the ball bearing retainer 6 having the embodiment (having both the flange portion 31 and the cutout portion 7) of the flange portion 31 described later together with fig. 10 to 14, the grease accommodation time is reduced by 50% as compared with a member having no cutout portion. Here, the "grease accommodation time" is the time required from the start of operation of the bearing to the stabilization of the temperature of the outer ring.

< test conditions >)

Testing machine: horizontal torque testing machine

The test model is as follows: 6312

Rotating speed: 5000. 10000min-1

Loading: fr 411N

And (3) testing: at each speed for 30 minutes

Confirming the item: outer ring temperature

< other embodiment >

In the following description, the same reference numerals are given to parts corresponding to the items described earlier in the respective embodiments, and redundant description is omitted. When only a part of the structure is described, the other parts of the structure are the same as those described above unless otherwise specified. The same structure can achieve the same effect. Not only the combinations of the portions specifically described in the respective embodiments but also the embodiments may be partially combined with each other as long as there is no particular obstacle to the combinations.

Fig. 10 to 14 show embodiment 2 of the present invention. The ball bearing retainer 6 of this embodiment is provided with a flange portion 31 that protrudes in the axial direction from the outer diameter edge of the connecting plate portion 14, in the ball bearing retainer 6 of embodiment 1 described together with fig. 1 to 6. The flange portions 31 extend to both sides of the web portion 14 in the axial direction, and are provided over the entire width of the web portion 14 in the circumferential direction of the bearing. As shown in fig. 14, the connecting plate portion 14 has wide portions 14a at both ends in the circumferential direction, but the axial position of the leading edge of the flange portion 31 is constant. An axial width dimension B (hereinafter referred to as "flange width") between the distal ends of the

flanges

14, 14 on both sides (fig. 12) is constant over the entire bearing circumferential direction and is substantially equal to the width dimension of the rolling surface 3a of the outer ring 3.

Fig. 14 is a view of the rolling bearing 1 as viewed from the inner ring 2 side toward the outer ring 3 side, and fig. 6 is a view of the rolling bearing of the first embodiment as viewed from the inner ring 2 side toward the outer ring 3 side. In the embodiment of fig. 6 in which the flange portion 31 is not provided, when the outer ring 3 is viewed from the inner ring 2 side, the rolling surface 3a of the outer ring 2 is visible on both sides of the connecting plate portion 14 of the ball bearing retainer 6 (a region 3aa where the rolling surface 3a is visible is indicated by a dot in fig. 6). In contrast, when the flange portion 31 is provided as in the embodiment of fig. 14, the rolling surface 3a of the outer ring 3 is hidden from view by the flange portion 31.

As shown in fig. 12, the cross section of the outer diameter side surface 31a of the flange portion 31 is perpendicular to the radial direction of the bearing, but the inner diameter side surface 31b is formed as an inclined surface having an inclination angle α with respect to the direction perpendicular to the radial direction of the bearing. The inclination angle α is, for example, 3 ° or more.

In this embodiment, since the flange portion 31 is provided, grease scraped off in the vicinity of the connecting portion 10A (fig. 7A) between the pocket wall portion 13 and the connecting plate portion 14 can be prevented from being drawn into the rolling surface 3a of the outer ring 3 by centrifugal force. This further shortens the time required for the discharge from the movement space in the vicinity of the rolling surface 3a of the outer ring 3 to the static space Sa (fig. 1) between the ball bearing cage 6 and the seal plate 4.

The flange width B (fig. 12) of the flange portion 31 is set to be substantially equal to the width of the rolling surface of the outer ring 3. Specifically, the flange width B is preferably 90 to 110%, more preferably 95 to 105%, of the outer ring raceway surface width. At 90% or less, the grease splashed by the centrifugal force cannot be prevented from being caught in the vicinity of the outer ring rolling surface 3a constituting the movement space. At least 110%, the grease is hindered by the flange 31 and is difficult to be discharged from the movement space. The inner diameter side surface of the flange 31 is tapered at 3 ° or more, so that grease can be more easily discharged from the movement space. At 3 ° or less, the grease is difficult to be discharged from the movement space.

As a reference example, even in the case where the notch portion 7 and the flange portion 31 are provided in the conventional iron plate wave-shaped cage, the same effect as that of the embodiment can be obtained by the operation of the grease. However, the iron plate cage has problems of time and labor consuming and high manufacturing cost.

< example of modification of the thick portion 8 >

As shown in embodiment 3 of fig. 15 to 17, the inner diameter portion of the pocket wall portion 13 may be formed axially outward of the other portions to form a thick portion 8. The thick portion 8 increases the thickness of the inner diameter portion of the pocket wall portion 13 in the bearing axial direction by the volume reduction amount caused by the notch portion 7. The thick portion 8 can suppress a decrease in rigidity of the ball bearing retainer 6 due to the notch portion 7.

As shown in embodiment 4 of fig. 18 to 20, the thick portion 8 may be formed so as to be thicker than other portions of the pocket wall portion 13 substantially along the outer surface of the pitch circle PCD (fig. 1) of the ball 5. In this case, the reduction in rigidity of the ball bearing retainer 6 due to the notch portion 7 can also be suppressed.

As shown in fig. 21 to 23 of embodiment 5, the inner diameter portion and the outer diameter portion of the pocket wall portion 13 may be formed axially outward of the other portions to form a thick portion 8. Also in this case, since the thick portion 8 is provided apart from the inner diameter portion and the outer diameter portion of the pocket wall portion 13, the balance of the ball bearing retainer 6 during the bearing operation is improved, and the rolling bearing can be further speeded up. Further, a reduction in the rigidity of the ball bearing retainer 6 due to the notch portion 7 can be suppressed.

As shown in fig. 24 to 26 of embodiment 6, the pocket wall portion 13 may be formed with a thick portion 8 having a tapered shape in which the outer surface becomes thick from the inner diameter surface toward the outer diameter surface. In this case, the thickness of the outer diameter side of the pocket wall portion 13 becomes thicker, so that the circumferential stress acting on the ball bearing cage 6 during the bearing operation can be resisted. Further, a reduction in the rigidity of the ball bearing retainer 6 due to the notch portion 7 can be suppressed.

< example of deformation of arrangement site of notch 7>

As shown in embodiment 7 of fig. 27, the cutout portion 7 may be provided on the outer diameter surface of the pocket wall portion 13. The outer diameter surface of the pocket wall portion 13 has a curved surface shape of a concave curve as viewed in the axial direction of the bearing. This configuration also achieves the same operational effects as those of embodiment 1.

< example of modification of the shape of notch 7>

The shape of the cutout portion 7, that is, the inner diameter surface or the outer diameter surface of the pocket wall portion 13 provided with the cutout portion 7 may be polygonal when viewed in the axial direction of the bearing. For example, the shape of the cutout portion 7 may be rectangular as shown in modification 1 of fig. 33, may be triangular as shown in modification 2 of fig. 34, or may be slit-like extending in the bearing radial direction as shown in modification 3 of fig. 35. As in the modification 1 of fig. 33, the width of the notch portion 7 in the bearing circumferential direction is equal to or more than half of the width of the groove wall portion in the bearing circumferential direction.

When the cutout portion 7 is rectangular and the deepest portion 7a of the cutout portion 7 is located in the vicinity of the pitch circle PCD of the ball 5, grease is more likely to flow out from the movement space Sa. The shape is not limited to the rectangular shape, and the grease can be more easily discharged from the movement space to the static space Sa if the cutout 7 having the arc-shaped curved shape is formed in a shape having a wide width in the bearing circumferential direction at a depth of the cutout 7 having an elliptical arc shape or the like in which the bearing is flattened in the radial direction. Although not shown, a contact seal may be used as a sealing plate used for a rolling bearing. The retainer for a ball bearing may be applied to an open type rolling bearing not provided with a seal plate. Each ring body of the ball bearing retainer may be formed by a 3D printer or machining.

However, in a high-speed region where the rotational speed exceeds dn 60 ten thousand, vibration of the cage, that is, resonance with natural vibration of the cage occurs at a predetermined rotational speed, and thus lubricant is involved and a rapid temperature rise occurs temporarily. A technique has been proposed in which the rigidity and natural frequency of the resin holder are increased by using a metal member to improve high-speed performance (patent document 4), but the use of a metal member increases the cost.

Therefore, as shown in embodiment 8 of fig. 28, the axial dimension (connecting portion thickness) t1 of the two connecting

plate portions

14 and 14 that overlap each other is set to 55% to 65% of the diameter of the ball 5 (fig. 29), so that the ball bearing retainer 6 has high rigidity and the natural frequency of the ball bearing retainer 6 is increased. By setting the lower limit of the axial dimension t1 to 55% of the ball diameter, the thickness (axial thickness) of the root Nm (fig. 28) of the ball bearing cage 6 surrounding the balls 5 (fig. 29) becomes large. Thus, the ball bearing retainer 6 has high rigidity and improved durability against centrifugal force at the time of high-speed rotation. Since the natural frequency increases due to the increased rigidity of the ball bearing retainer 6, resonance with the rotational speed does not occur. Therefore, vibration of the ball bearing retainer 6 due to resonance is not generated, and temperature rise is suppressed, and stable rotation is obtained.

The reason why the upper limit of the axial dimension t1 is 65% of the ball diameter is as follows.

65% of the ball diameter corresponds to 90% of the outer race width (outer race raceway surface width dimension) L1 shown in FIG. 29. In the rolling bearing 1, grease sealed between pockets (side surfaces of the respective connecting plate portions) of the ball bearing retainer 6 is scattered toward the outer ring 3 side radially outward by centrifugal force at the time of initial rotation. When the axial dimension t1 (fig. 28) is 90% or more of the outer ring groove width L1, the grease splashed by the centrifugal force is hard to be supplied to the rolling surface (raceway surface) 3 a. On the other hand, when the axial dimension t1 (fig. 28) is less than 90% of the outer ring groove width L1, grease is easily supplied to the raceway surface 3a, and the initial lubrication supply performance is improved. Therefore, the axial dimension t1 (fig. 28) has 65% corresponding to 90% of the outer ring groove width L1 as an upper limit.

Temperature rise tests were carried out with different thicknesses of the connecting portions.

< test conditions >

Testing machine: high speed tester (fig. 30)

Testing a bearing: model 6312

Rotating speed: from 3000min-1, the speed is increased to 13500min-1

Loading: axial load Fa 588.4N

Measurement items: bearing outer ring temperature

As shown in fig. 30, as a bearing for testing, two rolling bearings are provided at a predetermined interval in the axial direction, and an inner ring rotation type is formed by driving of the motor 24. The rolling bearing on the left side of fig. 30 close to the motor 24 is referred to as a motor-side bearing Br1, and the rolling bearing on the right side of fig. 30 is referred to as a motor-opposite-side bearing Br 2. In addition,

thermocouples

27 and 27 for measuring the outer ring temperature are provided in the case 26. The results of the temperature increase test are shown in fig. 31 and 32. As shown in the figure, the test bearing of the embodiment of fig. 28 in which the thickness of the connecting portion was increased can suppress a rapid temperature rise of the motor-side bearing Br1 and the non-motor-side bearing Br2, and can realize a high-speed operation with dn of 60 ten thousand or more, as compared with the product of the embodiment in which the thickness of the connecting portion was not increased.

As described above, although the preferred embodiments have been described with reference to the drawings, various additions, modifications, and deletions are possible within the scope of the present invention. Accordingly, such a mode is included in the scope of the present invention.

Description of reference numerals:

reference numeral 1 denotes a rolling bearing;

reference numeral 2 denotes an inner ring;

reference numeral 2a denotes a rolling surface;

reference numeral 3 denotes an outer ring;

reference numeral 3a denotes a rolling surface;

reference numeral 4 denotes a sealing plate;

reference numeral 5 denotes a ball;

reference numeral 6 denotes a ball bearing retainer;

reference numeral 7 denotes a notch portion;

reference numeral 8 denotes a thick-walled portion;

reference numeral 10 denotes an annular body;

reference numeral 12 denotes a pocket;

reference numeral 13 denotes a pocket wall portion;

reference numeral 14 denotes a web portion;

reference numeral 31 denotes a flange portion;

symbol Sa denotes a static space.

Claims

1. A retainer for a ball bearing, the retainer comprising 2 annular bodies made of synthetic resin and stacked on each other in an axial direction, each of the annular bodies comprising: a plurality of half-ball-shaped pocket wall portions which are arranged at predetermined intervals in a circumferential direction and which respectively constitute inner wall surfaces of pockets for holding balls; and a plurality of web portions that connect the circumferentially adjacent pocket wall portions to each other, wherein the 2 annular bodies are connected by overlapping the web portions, and wherein a notch portion is provided on an inner diameter surface or an outer diameter surface of the pocket wall portion so that a width of the pocket wall portion in a radial direction is smaller than a radial dimension of the web portion.

2. The ball bearing retainer according to claim 1, wherein an inner diameter surface or an outer diameter surface of the pocket wall portion of the cutout portion is a curved shape of a concave curve as viewed in a bearing axial direction.

3. The ball bearing holder according to claim 1 or 2, wherein a position in a bearing radial direction of a deepest portion of the cutout portion is located in the vicinity of the ball pitch circle.

4. The ball bearing retainer according to any one of claims 1 to 3, wherein the cutout portion is located on an outer diameter side of the pocket wall portion, and a flange portion protruding in an axial direction from an outer diameter edge of the connecting plate portion is provided.

5. The ball bearing retainer according to any one of claims 1 to 4, wherein the pocket wall portion has a thick portion whose thickness in the bearing axial direction is increased by an amount of volume reduction by the cutout portion.

6. A ball bearing retainer according to any one of claims 1 to 5, wherein the axial dimension of the two overlapping web portions is 55% to 65% of the diameter of the ball.

7. A rolling bearing comprising the ball bearing cage according to any one of claims 1 to 6.

8. Rolling bearing according to claim 7, wherein the balls are ceramic balls.