WO2024063023A1 - Solid-lubricated rolling bearing - Google Patents

Abstract

A solid-lubricated rolling bearing (1) comprises an outer race (2), an inner race (4), a plurality of rolling elements (6) interposed between the outer race (2) and the inner race (4), and a solid lubricating agent (10) separating the rolling elements (6) from one another in a circumferential direction. A volume ratio of the solid lubricating agent (10) occupying a bearing internal space between the outer race (4) and the inner race (2) is set to 40 to 60%. The solid lubricating agent (10) is guided on at least one of an inner diameter surface (2a) of the outer race (2) and an outer diameter surface (4a) of the inner race (4).

Description

Solid lubricated rolling bearing Related applications

This application claims priority to Japanese Patent Application No. 2022-149358 filed on September 20, 2022, and is cited in its entirety by reference as being part of this application.

The present invention relates to a solid-lubricated rolling bearing equipped with a solid lubricant for use in environments such as high temperatures and vacuums.

Solid lubricated rolling bearings are used in high-temperature environments, vacuum environments, etc. where grease or lubricating oil cannot be used as lubricants. As this type of solid lubricated rolling bearing, those described in Patent Document 1 and Patent Document 2 are conventionally known. In either configuration, components are used to separate the rolling elements and the solid lubricant from each other in the circumferential direction, and the solid lubricant is interposed between the two rolling elements. When the solid lubricant slides on the rolling elements and raceway rings, the lubricant is transferred to the rolling elements and raceway rings, or lubricant powder is generated on the rolling elements and raceway rings to lubricate the inside of the bearing.

Patent No. 6275433 Patent No. 3550689

In the bearing of Patent Document 1, a substantially U-shaped regulating member is employed as a component that separates the rolling elements and the solid lubricant in the circumferential direction. Further, in the bearing of Patent Document 2, a retainer that holds the rolling elements and the solid lubricant sandwiched therein is used as a component that separates the rolling elements and the solid lubricant in the circumferential direction. For this reason, in Patent Documents 1 and 2, it is difficult to make the diameter of the solid lubricant larger than the rolling element, and the wear life of the solid lubricant may be shortened.

An object of the present invention is to provide a solid lubricated rolling bearing that can extend the wear life of the solid lubricant.

The solid lubricated rolling bearing of the present invention includes an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a solid lubricant that separates the rolling elements in the circumferential direction. The solid lubricant rolling bearing is configured such that a volume percentage of the solid lubricant occupying an internal space of the bearing between the inner ring and the outer ring is set to 40 to 60%, and the solid lubricant is applied to the inner diameter surface of the outer ring or It is guided by at least one of the outer diameter surfaces of the inner ring.

According to this configuration, the solid lubricant separates the rolling elements in the circumferential direction and is guided on at least one of the inner diameter surface of the outer ring or the outer diameter surface of the inner ring. In other words, the solid lubricant causes the rolling elements to be spaced apart in the circumferential direction and is held relative to the inner and outer rings. Therefore, a regulating member that separates the rolling elements and the solid lubricant in the circumferential direction and a retainer that holds the rolling elements and the solid lubricant relative to the inner and outer rings can be omitted. In this way, by omitting the regulating member and the retainer, the solid lubricant can be made larger and the volume ratio can be optimized. Specifically, the volume percentage of the solid lubricant occupying the bearing internal space between the inner ring and the outer ring is set to 40 to 60%. The life of a solid lubricated rolling bearing corresponds to the wear life of the solid lubricant. According to the above configuration, the volume ratio of the solid lubricant occupying the internal space of the bearing is higher than that of the conventional technology, so that the life of the solid lubricated rolling bearing is extended.

In the present invention, the solid lubricant has a ring-shaped annular part and a plurality of pillar parts extending in the axial direction from the annular part and arranged at equal intervals in the circumferential direction, and the solid lubricant has A pocket portion in which the rolling element is housed may be formed between the portions. In this case, the distance between the column parts adjacent in the circumferential direction, that is, the pocket gap, may be set to 1.02 to 1.10 times the diameter of the rolling element.

By optimizing the pocket clearance in this way, ease of assembly and rotation in a stable posture are both achieved, and the wear life of the solid lubricant can be extended. In particular, by optimizing the pocket clearance in the early stages of operation, before the lubricant is transferred to the rolling elements and the inner and outer rings, or before the lubricant powder is generated on the rolling elements and the inner and outer rings, lubrication is most severe. The movement of the solid lubricant is suppressed, allowing rotation in a stable position. This increases the wear life of the solid lubricant.

Any combination of at least two configurations disclosed in the claims and/or the specification and/or the drawings is included in the present invention. In particular, any combination of two or more of each of the claims is included in the invention.

The invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation, and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same part numbers in multiple drawings indicate the same or corresponding parts.
FIG. 1 is a sectional view showing a solid lubricated rolling bearing according to a first embodiment of the present invention. It is a perspective view showing the solid lubricated rolling bearing.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following description, "axial direction", "radial direction" and "circumferential direction" refer to the "axial direction", "radial direction" and "circumferential direction" of the bearing, respectively.

FIG. 1 is a sectional view showing a solid lubricated rolling bearing 1 according to a first embodiment of the present invention, and FIG. 2 is a perspective view thereof. The solid lubricated rolling bearing 1 is used in a high temperature atmosphere (for example, 300° C. to 350° C.) or a vacuum atmosphere where grease or lubricating oil cannot be used as a lubricant.

The solid lubricated rolling bearing 1 shown in FIG. 1 includes an outer ring 2, an inner ring 4, and rolling elements 6 interposed between the outer ring 2 and the inner ring 4. In this embodiment, balls are used as the rolling elements 6. However, the rolling elements 6 are not limited to balls. Further, in this embodiment, the number of rolling elements 6 is eight, but the number of rolling elements 6 is not limited to this. The outer ring 2, the inner ring 4, and the rolling elements 6 are made of, for example, high carbon chromium bearing steel (SUJ2) treated with a manganese phosphate film. However, the materials, surface treatments, etc. of the outer ring 2, inner ring 4, and rolling elements 6 are not limited to these.

A raceway surface 2aa on which the rolling elements 6 roll is formed on the inner diameter surface 2a of the outer ring 2. The raceway surface 2aa is a surface recessed radially outward from the inner diameter surface 2a, and is located in the axial center of the inner diameter surface 2a. Further, annular outer locking grooves 2ab, 2ab are formed at both axial ends of the inner diameter surface 2a of the outer ring 2.

A raceway surface 4aa on which the rolling elements 6 roll is formed on the outer diameter surface 4a of the inner ring 4. The raceway surface 4aa is a surface that is recessed radially inward from the outer diameter surface 4a, and is located at the axial center of the outer diameter surface 4a. Furthermore, annular inner locking grooves 4ab, 4ab are formed at both axial ends of the outer diameter surface 4a of the inner ring 4.

The solid lubricated rolling bearing 1 also includes shields 8, 8 at both ends in the axial direction. The shields 8, 8 close the bearing internal space SP between the outer ring 2 and the inner ring 4 from both sides in the axial direction. That is, the shields 8, 8 prevent foreign matter from entering the bearing internal space SP. The shield 8 is, for example, a plate material made of SPTE (tinplate) treated with a manganese phosphate film. However, the material, surface treatment, etc. of the shield 8 are not limited to these.

The shield 8 has one end 8a (upper end in FIG. 1) supported by one of the inner and outer rings 4 and 2, and the other end 8b (lower end in FIG. 1) close to the other. In this embodiment, one end portion (upper end portion in FIG. 1) 8a is locked in the outer locking groove 2ab of the outer ring 2, and the other end portion (lower end portion in FIG. 1) 8b is locked in the inner locking groove 4ab of the inner ring 4. is sliding.

The solid lubricated rolling bearing 1 further includes a solid lubricant 10. When the solid lubricant 10 slides on the rolling elements 6 and the inner and outer rings 4 and 2 during bearing rotation, the lubricant 10 is transferred to the rolling elements 6 and the inner and outer rings 4 and 2, or lubricant powder of the lubricant 10 is transferred to the rolling elements 6 and the inner and outer rings 4 and 2. is generated by adhering to the rolling elements 6 and the inner and outer rings 4 and 2, thereby lubricating the inside of the bearing.

The solid lubricant 10 of this embodiment is a lubricant in which electrographite is impregnated with aluminum phosphate. Electrographite has better heat resistance than carbon graphite, and the impregnated aluminum phosphate moderately suppresses wear of the lubricant, contributing to the long life of the bearing. However, the material of the solid lubricant 10 is not limited to this.

As shown in FIG. 2, the solid lubricant 10 has a ring-shaped annular portion 12 and a plurality of pillar portions 14 extending in the axial direction from the annular portion 12 and arranged at equal intervals in the circumferential direction. It is a so-called comb-shaped solid lubricant. A pocket portion 16 is formed between adjacent pillar portions 14, 14, and the rolling element 6 is accommodated in the pocket portion 16. That is, the same number of pocket portions 16 as the rolling elements 6 are provided. Therefore, in this embodiment, eight pillar portions 14 and eight pocket portions 16 are provided.

In this way, the rolling elements 6 are spaced apart in the circumferential direction by the column portions 14 of the solid lubricant 10. Further, a pocket gap 18 exists between the columnar portion 14 and the rolling element 6. In other words, the distance (circumferential spacing) d2 between the pillar portions 14, 14 is larger than the diameter d1 (FIG. 1) of the rolling element 6 (d2>d1). For example, the distance d2 between the circumferentially adjacent columnar parts 14, 14 is set to 1.02 to 1.10 times the diameter d1 of the rolling element 6 (1.02≦(d2/d1)≦1 .10).

In this embodiment, as shown in FIG. 1, the solid lubricant 10 is guided by the inner diameter surface 2a of the outer ring 2 and the outer diameter surface 4a of the inner ring 4. Specifically, the outer diameter surface 10a of the solid lubricant 10 is guided by the inner diameter surface 2a of the outer ring 2, and the inner diameter surface 10b of the solid lubricant 10 is guided by the outer diameter surface 4a of the inner ring 4. In other words, the rolling elements 6 are positioned relative to the outer ring 2 and the inner ring 4 by the solid lubricant 10. In other words, the solid lubricant 10 also functions as a retainer that holds the rolling elements 6. In this way, the solid lubricant 10 of this embodiment has both the function of separating the rolling elements 6 in the circumferential direction and the function of holding the rolling elements 6. This makes it possible to omit the parts that space the rolling elements and the solid lubricant in the circumferential direction (hereinafter referred to as "separating parts") and the retainer.

In this embodiment, the solid lubricant 10 is guided on both the inner diameter surface 2a of the outer ring 2 and the outer diameter surface 4a of the inner ring 4, but only on one of the inner diameter surface 2a of the outer ring 2 and the outer diameter surface 4a of the inner ring 4. You may be guided by

In this way, the solid lubricant 10 can be made larger by omitting the spacer parts and the retainer. The life of the solid lubricant rolling bearing corresponds to the wear life of the solid lubricant, and the larger the solid lubricant 10, the longer the wear life of the solid lubricant 10. In this embodiment, the volume ratio of the solid lubricant 10 to the volume of the bearing internal space SP between the outer ring 2 and the inner ring 4 is set to 40 to 60%. Here, the "volume of the bearing internal space SP" is the radial space between the outer ring 2 and the inner ring 4, and refers to the volume of the ring-shaped space between both axial end surfaces of the bearing 1.

Next, experimental results of this embodiment will be explained. Table 1 shows the evaluation results of "life of the solid lubricant 10" and "rotability of the bearing" when the size of the solid lubricant 10, that is, the volume ratio of the solid lubricant 10 occupying the bearing internal space SP, changes. It shows. "〇" in the table means good, and "x" means bad.

In the example where the volume fraction was 20%, the solid lubricant 10 was small and the life was short. Furthermore, since the rolling elements 6 could not be held sufficiently, the vibrations were large and the rotatability was not good. In the 40% and 60% examples, the life of the solid lubricant 10 was sufficient, and the rotatability of the bearing was also good. In 80% of the cases, the life of the solid lubricant 10 was sufficient, but the large solid lubricant 10 easily interfered with other parts, and the rotatability of the bearing was not good. Therefore, the volume percentage of the solid lubricant 10 occupying the bearing internal space SP is preferably 40 to 60%.

Table 2 shows the evaluation results of "bearing rotational performance" when the size of the pocket clearance 18, that is, the ratio (d2/d1) of the distance d2 between the column portions 14, 14 to the diameter d1 of the rolling element 6, is changed. In the table, "◯" means good, "△" means somewhat good, and "×" means poor.

When (d2/d1) is less than 1.00, the pocket clearance 18 is an example of a "negative clearance". In an example in which (d2/d1) was less than 1.00, slipping occurred between the rolling elements 6 and the solid lubricant 10, and the rotatability was not good. In the example where (d2/d1) is 1.00 to 1.02, the rotatability was not bad, but because the pocket clearance 18 was small, there was large interference between the rolling elements 6 and the solid lubricant 10, and the rotatability was poor. It was not good. In the examples where (d2/d1) was 1.02 to 1.10, the rotatability was good. In an example in which (d2/d1) was larger than 1.10, the pocket gap 18 was large and the rolling elements 6 moved through the large pocket gap 18, resulting in large vibrations and poor rotatability. Therefore, the size (d2/d1) of the pocket gap 18 is preferably 1.02 to 1.10.

According to the above configuration, the solid lubricant 10 separates the rolling elements 6 in the circumferential direction and is guided by the inner diameter surface 2a of the outer ring 2 and the outer diameter surface 4a of the inner ring 4. That is, the solid lubricant 10 causes the rolling elements 6 to be spaced apart in the circumferential direction and is held relative to the inner and outer rings 4 and 2. Therefore, a spacing member that separates the rolling elements 6 and the solid lubricant 10 in the circumferential direction and a retainer that holds the rolling elements 6 and the solid lubricant 10 relative to the inner and outer rings 4 and 2 can be omitted. In this way, by omitting the spacing member and the retainer, the solid lubricant 10 can be made larger and the volume ratio can be optimized. The life of the solid lubricant rolling bearing 1 corresponds to the wear life of the solid lubricant 10. In the above configuration, the volume ratio of the solid lubricant 10 occupying the bearing internal space SP is higher than in the conventional technology, so that the solid lubricated rolling bearing has a longer life.

Furthermore, the distance between the circumferentially adjacent columnar parts 14, 14, ie, the pocket gap 18, is set to 1.02 to 1.10 times the diameter of the rolling element 6. By optimizing the pocket clearance 18 in this manner, ease of assembly and rotation in a stable posture are both achieved, and the wear life of the solid lubricant 10 can be extended. In particular, lubrication is most severe before the lubricant 10 is transferred to the rolling elements 6 and the inner and outer rings 4 and 2, or before lubricant powder of the lubricant 10 is generated on the rolling elements 6 and the inner and outer rings 4 and 2. By optimizing the pocket clearance 18 at the initial stage, the movement of the solid lubricant inside the bearing is suppressed, and rotation in a stable posture becomes possible. This extends the wear life of the solid lubricant 10.

The present invention is not limited to the above embodiments, and various additions, changes, or deletions can be made without departing from the gist of the present invention. For example, in the embodiment described above, balls are used as the rolling elements 6, but cylindrical rollers or conical rollers may be used. Therefore, such materials are also included within the scope of the present invention.

Reference Signs List 1 Solid-lubricated rolling bearing 2 Outer ring 2a Inner diameter surface of outer ring 4 Inner ring 4a Outer diameter surface of inner ring 6 Rolling element 10 Solid lubricant 12 Ring portion 14 Column portion 16 Pocket portion SP Bearing internal space

Claims (3)

1. A solid lubricated rolling bearing comprising an inner ring, an outer ring, a plurality of rolling elements interposed between the inner ring and the outer ring, and a solid lubricant that separates the rolling elements in the circumferential direction,
   A volume percentage of the solid lubricant occupying an internal space of the bearing between the inner ring and the outer ring is set to 40 to 60%,
   A solid lubricated rolling bearing, wherein the solid lubricant is guided on at least one of an inner diameter surface of the outer ring or an outer diameter surface of the inner ring.
2. The solid lubricant rolling bearing according to claim 1, wherein the solid lubricant includes a ring-shaped annular portion and a plurality of pillar portions extending in the axial direction from the annular portion and arranged at equal intervals in the circumferential direction. has
   A solid lubricated rolling bearing in which a pocket portion in which the rolling element is accommodated is formed between the adjacent pillar portions.
3. The solid lubricated rolling bearing according to claim 2, wherein the distance between the circumferentially adjacent column parts is set to 1.02 to 1.10 times the diameter of the rolling element.

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