WO2017043425A1

WO2017043425A1 - Rolling bearing

Info

Publication number: WO2017043425A1
Application number: PCT/JP2016/075852
Authority: WO
Inventors: 貴行鈴木; 清茂山内
Original assignee: Ntn株式会社
Priority date: 2015-09-10
Filing date: 2016-09-02
Publication date: 2017-03-16
Also published as: JP2017053450A

Abstract

This retainer (4) comprises: a resin main body part (6) in which openings (6a) corresponding to pockets (5) are formed at predetermined intervals in the circumferential direction; and a cover part (7) fixed to the resin main body part (6). The cover part (7) has the following three characteristics, i.e., a smaller water absorption rate, a smaller linear expansivity, and a higher elastic modulus compared to the resin main body part (6). A guided surface (7b) of the retainer is constituted by a resin surface formed on the cover part (7).

Description

Rolling bearing

This invention relates to a rolling bearing suitable for a revolving part such as a planetary rotating body provided in a planetary reduction gear, and more particularly to guiding a cage.

Generally, a rolling bearing includes a cage for maintaining a circumferential interval between rolling elements. In the cage, pockets for storing rolling elements are formed at equal intervals in the circumferential direction. Examples of the type of cage include a press cage formed of a steel plate (for example, Patent Literature 1 below) and a resin cage formed of a resin (for example, Patent Literature 2 below). As a method for guiding the cage, a rolling element guide method (for example, Patent Document 2) that guides the cage by a rolling element, or a bearing ring guide method (for example, a guide that guides the cage by a race ring (outer ring or inner ring)) (for example, The following patent documents 1, 3) are employed.

JP 2004-293730 A JP 2005-69282 A JP 2008-196582 A

However, when used in revolving parts, the lubricating oil inside the cage and bearings must have a rolling bearing that revolves integrally with the planetary rotating body in addition to centrifugal force due to rotation around the bearing center axis of the cage. Centrifugal force also acts. The centrifugal force due to the revolution causes a load region in the rolling bearing, and causes deformation and eccentricity of the cage, and bias of the lubricating oil inside the bearing.

For example, in a dump truck or the like, a final reduction gear is disposed inside the wheel rim. In order to obtain a large reduction ratio, this final reduction gear generally has a structure in which planetary reduction gears are combined in a plurality of stages, and the output from the final stage planetary reduction gears is transmitted to the wheel rim. The planetary rotating body provided in the planetary reduction gear is composed of a planetary gear or a planetary roller that revolves while rotating between a ring gear and a sun gear, and is supported on a carrier shaft via a rolling bearing (for example, Patent Document 3). .

When the inventors of the present application examined the use environment in the final reduction gear of the current ultra-large dump truck, the revolution diameter of the rolling bearing was around 500 mm, the revolution speed exceeded 500 rpm, and the bearing rotation speed became about 1300 rpm. The maximum centrifugal acceleration was about 75G. When such strong centrifugal acceleration is applied, the lubricating oil inside the bearing becomes dilute in the load region, and the tendency to deviate to the opposite side in the circumferential direction from the load region is remarkable.

The press cage is excellent in deformation resistance when a strong centrifugal acceleration is applied, but self-lubricating property cannot be expected on a metal surface such as a guided surface guided by rolling elements or bearing parts of a bearing ring. There is anxiety about using it in an environment where the lubricant is diluted.

On the other hand, the resin cage is superior in sliding property to the guided surface and lighter in weight than the press cage, so that the bearing component (the bearing ring or the roller that can come into contact with the cage in the radial direction) due to strong centrifugal acceleration. The aggressiveness to the moving body is small, and it is advantageous for bearing damage as a result. However, it is easy to be deformed when centrifugal acceleration is applied, and the guide clearance between the guided surface and the bearing parts is within an appropriate range. It may not be possible to keep. As the deformation, for example, in the case of the raceway guide method, there is an elliptical deformation caused by the guided surface of the cage being pressed against the cage guide surface of the raceway. In the case of the rolling element guide method, elliptic deformation due to a tensile force acting on the cage in accordance with the revolution speed difference between the rolling elements can be mentioned.

In addition, in the case of a resin cage, in addition to the effect of centrifugal acceleration, temperature rise or expansion due to water absorption occurs. This expansion deformation also causes the guide clearance to go wrong.

In view of the above-mentioned background, the problem to be solved by the present invention is that the cage of the rolling bearing is light in weight, and the slidability of the guided surface is good, but the cage deformation that derails the guide clearance It is to suppress.

To achieve the above object, the present invention provides a rolling bearing comprising a cage having pockets formed at predetermined intervals in the circumferential direction and a bearing component for guiding the cage, wherein the cage is arranged in the circumferential direction. It consists of a resin body part in which openings corresponding to the pockets are formed at predetermined intervals, and a covering part fixed to the resin body part, and the covering part has a smaller water absorption rate and smaller than the resin body part. It has at least one of the three properties of linear expansion coefficient and high elastic modulus, and the guided surface guided by the bearing component among the surfaces of the cage is from the resin surface formed on the covering portion. Is adopted.

According to the said structure, a retainer can be reduced in weight by employ | adopting the resin main-body part by which the opening corresponding to a pocket was formed in the circumferential direction at predetermined intervals. When the covering portion fixed to the resin main body portion has a smaller water absorption rate than the resin main body portion, it is possible to suppress expansion deformation due to water absorption on the guided surface formed of the resin surface formed in the covering portion. it can.
Moreover, when the coating | coated part has a small linear expansion coefficient compared with the resin main-body part, the expansion deformation by a temperature rise can be suppressed in the to-be-guided surface which consists of the resin surface formed in the coating | coated part.
In addition, when the covering portion has a higher elastic modulus than the resin main body portion, on the guided surface made of the resin surface formed on the covering portion, deformation due to centrifugal acceleration or a difference in revolution speed between rolling elements is suppressed. be able to.
Further, the slidability of the guided surface is good because it consists of the resin surface of the covering portion.

As described above, the present invention employs the above-described configuration, and the cage of the rolling bearing is lightweight, and the slidability of the guided surface is good, but the cage deformation that detracts from the guide clearance is suppressed. can do.

Sectional drawing which shows the structure of the rolling bearing which concerns on 1st embodiment of this invention. Sectional view taken along line II-II in FIG. Sectional drawing which shows the structure of the rolling bearing which concerns on 2nd embodiment of this invention. Sectional drawing which shows the structure of the rolling bearing which concerns on 3rd embodiment of this invention. Sectional drawing which shows the structure of the planetary reduction gear incorporating the rolling bearing which concerns on either embodiment. Sectional view taken along line VI-VI in FIG.

Hereinafter, a first embodiment of the present invention will be described with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the rolling bearing according to the first embodiment includes an inner ring 1, an outer ring 2, a plurality of rolling elements 3 interposed between the two

wheels

1 and 2, and the rolling elements 3 around the rolling elements 3. And a cage 4 equally arranged in the direction. The center axis of both

wheels

1 and 2 and the center axis of the cage 4 coincide with the bearing center axis of the rolling bearing. Hereinafter, the direction along the bearing central axis is simply referred to as “axial direction”, the direction perpendicular to the central axis is simply referred to as “radial direction”, and the circumferential direction around the central axis is simply referred to as “circumferential direction”. It is called “circumferential direction”.

The inner ring 1 is a bearing part having a raceway surface on the outer peripheral side. The outer ring 2 is a bearing component having a raceway surface on the inner peripheral side.

The rolling element 3 consists of a tapered roller.

The rolling bearing of the first embodiment is a single-row tapered roller bearing. An inner ring assembly is constituted by the inner ring 1, the plurality of rolling elements 3 and the cage 4. In addition, the rolling element 3 may be a cylindrical roller or a spherical roller, may be a ball, and may be arranged in a double row.

The cage 4 is a cage type cage. Pockets 5 are formed in the retainer 4 at predetermined intervals in the circumferential direction. The pocket 5 is a space for accommodating the rolling elements 3.

The retainer 4 includes a resin main body 6 in which openings 6 a corresponding to the pockets 5 are formed at predetermined intervals in the circumferential direction, and a covering portion 7 fixed to the resin main body 6.

The opening 6a has a shape on the premise that the shape of the pocket 5 is completed by fixing the covering portion 7 to the resin main body portion 6.

The covering portion 7 is made of a resin molding layer fixed on the entire surface of the resin main body portion 6.

As a result, the covering portion 7 is fixed over the entire circumference in the circumferential direction of the resin main body portion 6.

Further, the covering portion 7 is fixed to the resin main body portion 6 so as to enclose each partition portion of the resin main body portion 6 that separates the

openings

6a and 6a in the circumferential direction.

Further, among the surfaces of the cage 4, the pocket inner surface portion 7 a that receives the rolling elements 3 in the circumferential direction is made of a resin surface formed on the covering portion 7.

Also, the guided surface 7 b guided by the bearing component among the surfaces of the cage 4 is also made of a resin surface formed on the covering portion 7. A bearing part that guides the cage 4 includes an outer ring 2. The guided surface 7 b slides on the cage guide surface 2 a formed on the outer ring 2.

The resin main body 6 is made of polyamide (PA). The covering portion 7 is formed of an epoxy resin.

For example, polyamide (PA) has a water absorption rate of 2 [%], a linear expansion coefficient of 2 to 7 [× 10 ⁻⁵ / ° C.], and a tensile modulus of elasticity of about 8000 [MPa]. On the other hand, the epoxy resin has a water absorption rate of 0.2 [%], a linear expansion coefficient of 1 to 5 [× 10 ⁻⁵ / ° C.], and a tensile elastic modulus of about 20000 [MPa]. Therefore, the covering portion 7 formed of epoxy resin has a clearly smaller water absorption rate and higher elastic modulus than the resin main body portion 6 formed of polyamide (PA), and has the same linear expansion coefficient. In particular, by using an epoxy resin having a linear expansion coefficient of less than 2 [× 10 ⁻⁵ / ° C.], the covering portion 7 has a smaller linear expansion coefficient than the resin main body portion 6.

Also, epoxy resin has better self-lubricating properties than polyamide (PA). For this reason, the slidability of the surface of the epoxy resin formed on the covering portion 7 is superior to that of the polyamide (PA) surface of the resin main body portion 6.

In addition, the coating | coated part 7 should just be comprised so that it may have at least 1 property among three properties of a small water absorption rate, a small linear expansion coefficient, and a high elasticity modulus compared with the resin main-body part 6. FIG. Examples of other resin materials that can be used for forming the resin main body 6 include engineering plastics such as polyacetal (POM), polycarbonate (PC), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT). Examples of the resin material that can be used for forming the covering portion 7 include polyamideimide (PAI), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone (PSF), Super engineering plastics such as polyethersulfone (PES), polyimide (PI), and polyetherimide (PEI) can be mentioned. For example, in the case of polyamideimide, the water absorption rate is 0.2 [%], the linear expansion coefficient is 3 [× 10 ⁻⁵ / ° C.], and the tensile modulus is about 5000 [MPa]. Therefore, when the resin body portion is formed of polyamide (PA) and the covering portion is formed of polyamideimide (PAI), the resin body portion has a clearly smaller water absorption rate than that of the resin body portion and has the same linear expansion coefficient or A covering portion having a high linear expansion coefficient can be formed.

The retainer 4 can be manufactured by, for example, disposing the resin main body portion 6 in the cavity and transfer molding the covering portion 7.

The rolling bearing of the first embodiment is as described above, and most of the cage 4 is constituted by the resin main body portion 6 in which openings 6a corresponding to the pockets 5 are formed at predetermined intervals in the circumferential direction. Therefore, the cage 4 can be reduced in weight as compared with the case where the whole is made of an iron-based material. This is less offensive to the bearing component (the outer ring 2 or the rolling element 3 that can come into contact with the cage 4 in the radial direction) due to strong centrifugal acceleration, resulting in an advantage against bearing damage.

In the rolling bearing of the first embodiment, the cage 4 includes a resin main body portion 6 and a covering portion 7 fixed to the resin main body portion 6. The covering portion 7 is smaller in water absorption than the resin main body portion 6. Of the surface of the cage 4, the guided surface 7 b guided by the bearing component (outer ring 2) is made of the resin surface formed on the covering portion 7, so that the entire cage is the same as the resin main body portion 6. Compared to the case of forming with a resin material, expansion deformation of the guided surface 7b due to water absorption can be suppressed. That is, by reducing the guide clearance between the guided surface 7b and the cage guide surface 2a, it is possible to prevent an increase in rotational torque and an increase in the amount of heat generated in the sliding contact area of the both

surfaces

7b, 2a.

Further, in the rolling bearing of the first embodiment, the covering portion 7 has a smaller linear expansion coefficient than the resin main body portion 6, and the guided surface 7 b is made of a resin surface formed on the covering portion 7. Compared to the case where the entirety is formed of the same resin material as that of the resin main body 6, the expansion deformation of the guided surface 7b due to the temperature rise can be suppressed. This is also effective in preventing an increase in rotational torque and an increase in heat generation due to a decrease in guide clearance.

Further, in the rolling bearing of the first embodiment, the covering portion 7 has a higher elastic modulus than the resin main body portion 6 and the guided surface 7b is made of a resin surface formed on the covering portion 7. Therefore, the entire cage As compared with the case where is formed of the same resin material as that of the resin main body 6, the elliptical deformation of the cage 4 due to the centrifugal acceleration or the difference in the revolution speed between the rolling elements can be suppressed. This is equivalent to suppressing uneven distribution of guide clearances and pocket clearances (clearance between the pockets 5 and the rolling elements 3) due to elliptical deformation, thereby preventing a situation where proper cage guidance is hindered. It will also be a thing.

Furthermore, since the rolling bearing of the first embodiment includes each partition portion that separates the

openings

6a and 6a in the circumferential direction in the surface of the resin main body portion 6, the covering portion 7 includes the water absorption and temperature described above. The expansion deformation of the pocket inner surface portions 7a, 7a due to the rise can be suppressed, the deformation of the column of the cage 4 due to the above-described centrifugal acceleration and the revolution speed difference can be suppressed, and the elliptical deformation of the cage 4 can be suppressed.

Furthermore, since the rolling bearing of the first embodiment is composed of a resin surface in which the guided surface 7b guided by the bearing component (the bearing ring 2) is formed on the covering portion 7 among the surfaces of the cage 4, the guided bearing is provided. The slidability of the surface 7b is good.

Furthermore, since the rolling bearing of the first embodiment is formed of a resin molding layer in which the covering portion 7 is fixed on the entire surface of the resin main body portion 6, the above-described elliptic deformation of the cage 4 can be most effectively suppressed. it can.

Further, in the rolling bearing of the first embodiment, since the resin main body portion 6 is formed of polyamide (PA) and the covering portion 7 is formed of epoxy resin, the covering portion 7 is compared with the resin main body portion 6. Therefore, it is possible to obtain the covering portion 7 having a small water absorption rate, a small linear expansion coefficient, and a high elastic modulus and having excellent slidability.

Furthermore, in the rolling bearing of the first embodiment, since the cage 4 is guided by the raceway ring 2, it is not necessary to set the pocket clearance as narrow as in the rolling element guide system. Even when the cage 4 is elliptically deformed due to the revolution speed difference, strong contact between the cage 4 and the rolling element 3 can be prevented.

Further, in the rolling bearing of the first embodiment, since the bearing part for guiding the cage 4 is composed of the outer ring 2, compared with the case where the cage is guided by the inner ring 1, the covered bearing formed on the outer circumference of the cage 4. The circumferential length of the guide surface 7b and the cage guide surface 2a is increased, the peripheral speed difference and the contact surface pressure at the sliding contact portion of the both

surfaces

7b, 2a are reduced, and the lubricating oil is moved to the outer ring 2 side by centrifugal force. For this reason, the guided surface 7b is unlikely to be short of lubricating oil, which is advantageous in preventing wear and seizure of the guided surface 7b.

Furthermore, the rolling bearing of the first embodiment is resistant to the above-described elliptical deformation on the outer diameter side of the cage because the covering portion 7 is continuous over the entire outer periphery of the resin main body portion 6. Excellent resistance to elliptical deformation compared to resistance to elliptical deformation on the inner diameter side of the vessel.

In the first embodiment described above, the raceway guide system is exemplified, but when the rolling element guide system is used, the cage 4 is guided by the rolling element 3 in contact with the pocket inner surface portions 7a and 7a of the covering portion 7. The pocket clearance and the clearance between the bearing ring and the cage may be set, and the illustration and explanation thereof will be omitted.

In the above-described first embodiment, the opening 6a is a precondition for completing the shape of the pocket 5 by fixing the covering portion 7, but the opening may be a pocket. Further, in the first embodiment, the covering portion 7 is a resin molding layer that covers the entire surface of the resin main body portion 6. However, the resin main body portion of the resin main body portion is formed so that at least the resin surface that becomes the guided surface 7b is formed on the covering portion. It may be fixed to the part. FIG. 3 shows a second embodiment as an example. In the following, only differences from the first embodiment will be described.

The cage 10 of the second embodiment shown in FIG. 3 covers only the outer peripheral surface, the inner peripheral surface and the side surface of the resin main body 11 on one side in the axial direction (large diameter side in the illustrated example) over the entire circumference. The covering portion 12 is fixed to the surface.

Since the rolling bearing of the second embodiment forms a pocket as shown in FIG. 2 as the opening of the resin main body 11, the pocket size at the time of manufacturing the cage is suppressed while suppressing deformation of the guided surface 12a during the operation of the bearing. There is an advantage that it is easy to stabilize.

In the illustrated example, the resin body 11 is covered from three sides of the inner diameter side, the outer diameter side, and one side surface in order to improve the fixability of the covering portion 12 to be fixed to a part of the resin body portion 11. . In order to improve the fixing property of the covering portion 12, irregularities such as grooves and dimples may be formed on the surface portion of the resin main body portion 11 covered with the covering portion 12.

In the first and second embodiments described above, the covering portion is a resin molding layer made of a single resin material, but the covering portion may be composed of a plurality of materials. FIG. 4 shows a third embodiment as an example.

The cage 20 of the third embodiment shown in FIG. 4 has a covering part 22 made of an annular part fitted to the resin main body part 21. The range in which the covering portion 22 is fitted is the same as in the second embodiment.

The covering portion 22 includes an annular core 23 made of iron and a coating layer 24 fixed to the annular core 23. Here, iron refers to iron-based materials such as pure iron, steel (including stainless steel), and cast iron.

In iron, the water absorption rate is substantially 0 [%], the linear expansion coefficient is 1 [× 10 ⁻⁵ / ° C.], and the tensile elastic modulus is about 206000 [MPa]. Therefore, the linear expansion coefficient and elastic modulus as a whole of the covering portion 22 are sufficiently high to suppress the elliptical deformation of the cage 20 due to the nature of the iron of the annular core 23 occupying most of the covering portion 22. Can be secured.

The coating layer 24 is made of polyamideimide (PAI) or polytetrafluoroethylene (PTFE). The resin surface of the coating layer 24 becomes a guided surface. Polyamideimide (PAI) is excellent in wear resistance in addition to good dimensional stability (particularly low water absorption) and slidability. Polytetrafluoroethylene (PTFE) also has good dimensional stability (water absorption: substantially 0 [%]), and good slidability can be obtained even if it is adopted. As described above, it has a water absorption rate of 0.2 [%] suitable as a guided surface, and has good slidability.

The rolling bearing according to the third embodiment is suitable when priority is given to the diversity of the material selection of the covering portion since the covering portion 22 is a separately-made annular part fitted to the resin main body portion 21. For example, when a coating portion satisfying the above-mentioned three properties cannot be obtained with only polyamideimide (PAI) or polytetrafluoroethylene (PTFE), an iron annular cored bar 23 and a coating layer such as polyamideimide (PAI) The above-mentioned three properties can be satisfied by configuring the covering portion 22 from 24.

5 and 6 illustrate a planetary speed reducer incorporating the rolling bearing 100 according to any one of the above-described embodiments. In this planetary reduction gear, a plurality of planetary rotating bodies 105 as planetary gears meshing with both

gears

102, 104 are arranged between a sun gear 102 attached to the input shaft 101 and an internal gear 104 fixed to the housing 103. Each planetary rotator 105 is rotatably supported with respect to the carrier 107 connected to the output shaft 106, and the revolving motion of the planetary rotator 105 revolving while rotating between the sun gear 102 and the internal gear 104 is It is output to the output shaft 106 via the carrier 107.

A pair of rolling bearings 100 are disposed between the planetary rotating body 105 and the carrier 107 provided in the planetary reduction gear. The outer ring of each rolling bearing 100 is attached to the planetary rotator 105 and rotates integrally with the planetary rotator 105. The inner ring of each rolling bearing 100 is attached to a support shaft 108 provided on the carrier 107 and is stationary with respect to the outer ring.

The planetary speed reducer shown in the figure performs the first speed reduction of the final speed reducer provided inside the wheel rim of the super large dump truck. The super large dump truck is intended for mines and has a load capacity of 300 t or more. As the usage environment of the roller bearing 100, the revolution diameter of the roller bearing 100 revolving around the sun gear 102 is about 500 mm, the revolution speed is about 500 rpm, the bearing rotation speed at this time is about 1300 rpm, and the maximum centrifugal acceleration is about 75 G. Assumed.

As described above, the rolling bearing 100 suppresses elliptical deformation of the cage, absorbs the moisture of the lubricating oil supplied to the rolling bearing 100, and expands the guided surface of the cage due to the temperature rise of the lubricating oil. Therefore, abnormal wear on the guided surface of the cage and the inner surface of the pocket is possible even in a usage environment where strong centrifugal acceleration is applied, such as the final reduction gear of an ultra-large dump truck. Can be prevented.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. Accordingly, the scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 2a Cage guide surface 3

Rolling body

4, 10, 20 Cage 5

Pocket

6, 11, 21 Resin body

part 6a Opening

7, 12, 22 Covering part 7a Pocket

inner surface part

7b, 12a Guided surface 23 Annular Core 24 coating layer

Claims

In a rolling bearing comprising a cage (4, 10, 20) in which pockets (5) are formed at predetermined intervals in the circumferential direction, and a bearing component for guiding the cage (4, 10, 20),
The retainer (4, 10, 20) includes a resin main body (6, 11, 21) in which openings (6a) corresponding to the pockets (5) are formed at predetermined intervals in the circumferential direction, and the resin main body. (6, 11, 21) and a covering portion (7, 12, 22) fixed to
The covering portion (7, 12, 22) has at least one property among three properties of a small water absorption rate, a small linear expansion coefficient and a high elastic modulus as compared with the resin main body portion (6, 11, 21). And
Of the surfaces of the cages (4, 10, 20), guided surfaces (7b, 12a) guided by the bearing parts are made of resin surfaces formed on the covering portions (7, 12, 22). A rolling bearing characterized by that.
The covering portion (7, 12, 22) has a higher elastic modulus than the resin main body portion (6, 11, 21), and the entire circumference in the circumferential direction of the resin main body portion (6, 11, 21). The rolling bearing according to claim 1, which is fixed over the entire area.
The rolling bearing according to claim 1, wherein the covering portion (7) includes each partition portion that separates the openings (6 a) in the circumferential direction out of the surface of the resin main body portion (6). .
The rolling bearing according to any one of claims 1 to 3, wherein the covering portion (7, 12) is formed of a resin molding layer fixed to a part or the entire surface of the resin main body portion (6, 11).
The resin main body (6, 11) is made of polyamide,
The rolling bearing according to claim 4, wherein the covering portions (7, 12) are formed of an epoxy resin.
The rolling bearing according to claim 2, wherein the covering portion (22) is formed of an annular part fitted into the resin main body portion (21).
The covering portion (22) comprises an annular cored bar (23) formed of iron and a coating layer (24) fixed on the annular cored bar (23),
The rolling bearing according to claim 6, wherein the coating layer is made of polyamideimide or polytetrafluoroethylene.
The rolling bearing according to any one of claims 1 to 7, wherein the covering portion (7, 12, 22) is continuous over the entire outer periphery of the resin main body portion (6, 11, 21).
The rolling bearing according to any one of claims 1 to 8, wherein the rolling bearing is disposed between a planetary rotating body (105) and a carrier (107) provided in the planetary reduction gear.