US-12624730-B2 - Roller bearing

US12624730B2US 12624730 B2US12624730 B2US 12624730B2US-12624730-B2

Abstract

A roller bearing includes an outer ring, an inner ring, and plural rolling elements rollably interposed between mutual raceway surfaces of the outer and inner rings, and is used by fitting an outer diameter surface of the outer ring serving as a fitting surface to a housing serving as a mating member or by fitting an inner diameter surface of the inner ring serving as a fitting surface to a shaft serving as the mating member. The fitting surface is provided with at least one protrusion so that a static torque T hold =Σ(F×r) generated by the protrusion is equal to or greater than a torque T creep generated by creep.

Inventors

Tomohiro Motoda

Assignees

NSK LTD.

Dates

Publication Date: 20260512
Application Date: 20210126
Priority Date: 20200207

Claims (4)

1 . A roller bearing comprising: an outer ring having a first side that defines a mounting surface and a second side that is opposite to the first side and that defines an outer ring raceway surface; an inner ring having a first side the defines a mounting surface and a second side that is opposite to the first side and that defines an inner ring raceway surface; and a plurality of rolling elements rollably interposed between the outer ring raceway surface and the inner ring raceway surface, wherein the mounting surface of the outer ring is configured to non rollably couple the roller bearing to a housing, the mounting surface of the inner ring is configured to non rollably couple the inner ring to a shaft, the mounting surface of the outer ring has a first region in which protrusions are defined and a second region that is: i) adjacent to the first region, and ii) devoid of any protrusions, and the first region extends from a first axial end of the mounting surface of the outer ring to a second axial end of the mounting surface of the outer ring, and the first region is only one region, and a second region, which is a remainder of the mounting surface of the outer ring, is larger than the first region and is devoid of any protrusions.
2 . The roller bearing according to claim 1 , wherein the first region defines a line that extends along the axial direction of the roller bearing.
3 . The roller bearing according to claim 1 , wherein the protrusions have a conical shape.
4 . An apparatus comprising: the roller bearing according to claim 1 , wherein the protrusions of the outer ring frictionally engage the housing to thereby prevent creep of the roller bearing.

Description

TECHNICAL FIELD The present invention relates to roller bearings, and in particular, to roller bearings used in such a state that creep of a raceway ring occurs or may occur with respect to a mating member such as a housing. Here, in roller bearings, when used by fitting an outer diameter surface of an outer ring to a housing or by fitting a shaft to an inner diameter surface of an inner ring, a phenomenon in which the outer or inner ring rotates relative to a mating member such as the housing or the shaft may occur. The phenomenon is called creep. BACKGROUND ART Due to a demand for reduction in sizes and weights of various rotating mechanical devices, some roller bearings are becoming thinner in a raceway ring such as an outer or inner ring. In the case of a roller bearing whose outer ring is fitted to a housing, thinning of the outer ring causes significant elastic deformation of an outer diameter surface of the outer ring under rolling element load. Changes in strain of the outer diameter surface of the outer ring caused by repetitive application of the rolling element load cause outer ring creep. At this time, the outer diameter surface of the outer ring rubs against an inner surface of the housing, thereby causing wear on the housing and the outer diameter of the outer ring. As the wear increases, rattling occurs in a rotation supporting portion of the rotating machine device, which causes abnormal vibration and failure of the rotating machine device. Even when the inner ring is made thinner, the same phenomenon (inner ring creep) occurs. In this case, the shaft and the inner diameter of the inner ring are worn. To prevent creep from occurring on the outer diameter surface of the outer ring, for example, PTL 1 describes a technology in which an axial direction shape of the outer diameter surface of an outer ring is machined not into a straight one but a shape with an arc-shaped recess. Then, the bearing with such a recess formed on the outer diameter surface of the outer ring is press-fitted into a housing, and a large tightening allowance formed at both ends of the outer ring prevents the occurrence of creep. However, in the technology described in this literature, the outer ring needs to be press-fitted into the housing with a large force, and it is not easy to attach the outer ring. Besides that, although pins and flanges may be provided to prevent rotation, the number of parts increases, and the shapes of the bearing and the housing become complicated. Therefore, in addition to increased machining cost and size, manufacturing cost also increases because the work of attaching the bearing to the housing becomes complicated. PTL 2 describes a technology of covering the outer diameter surface of an outer ring with a lubricating film made of a thermosetting synthetic resin composition containing molybdenum disulfide, antimony, and the like. The lubricating film has lubricity and is essentially resinous. Therefore, the lubricating film is softer than aluminum and aluminum alloys, which are common housing materials, and even when creep occurs, wear of an inner peripheral surface of the housing can be prevented. Additionally, since it is only necessary to form the lubricating film, the technology is applicable to various types of roller bearings and is also highly versatile. However, the lubricating film in this literature is obtained by applying a solution of a thermosetting synthetic resin composition containing molybdenum disulfide or the like dissolved in a solvent and heating to evaporate the solvent, and may not be sufficient in film strength and durability. A technology described in PTL 3 provides an O-ring on the outer diameter surface of an outer ring to fill a gap between a housing and a bearing, and repulsive force of rubber forming the O-ring prevents creep. However, when the housing unexpectedly expands, the repulsive force of the rubber is reduced, and creep may occur. Additionally, a step of cutting a groove in the rubber, and the rubber itself or a step of combining them are costly, resulting in increased manufacturing cost. In a technology described in PTL 4, the wall thickness of an outer ring is thickened to increase rigidity, thereby suppressing elastic deformation of the outer ring to prevent the occurrence of creep. However, to completely prevent the occurrence of creep, the wall thickness of the outer ring must be very thick. This can easily lead to an increase in bearing size. In a technology described in PTL 5, a piston ring is covered with a heat-resistant resin containing molybdenum disulfide, antimony, and the like. Polyamide imide is used as the heat-resistant resin, and phenol resin is used as a curing agent. The technology described in this literature uses phenol resin as the curing agent, and therefore, firing in Examples is performed at from 180 to 220° C. However, SUJ 2, which is widely used for bearings, has a firing temperature of approximately 120° C., and thus cannot b