Patent Application
20140314363
The present disclosure relates to an inner ring for a roller bearing assembly, in particular an inner ring for a spherical roller bearing assembly with a first portion for receiving the roller bearings and a second portion for mounting the inner ring. The second portion is annealed to have a hardness less the first portion.
It is known to harden an inner ring for a bearing assembly to reduce wear due to contact of the inner ring with rolling elements in the assembly. However, the hardening in portions of the inner ring operated upon to form features (for example, slot or hole) for mounting the inner ring can result in fracturing, cracking, or weakening of the portions as a result of the operations, reducing durability and causing early failure of the inner ring. Further, cracking, fracturing, or other failure of the mounting or second portion can occur during mounting or servicing operations.
Hardness of materials can be measured. For bearing steels there are a variety of measurement systems, including Vickers (HV), Brinell (BHN) and Rockwell (HRB or HRC) hardness. In general, as hardness of a material, such as bearing steel, increases so does brittleness (i.e. the material is more susceptible to sudden fractures when stressed). It is typically advantageous to have a hard material at areas of high surface stress, such as at the contact area between a rolling element and a raceway of a bearing assembly. Conversely, it is typically advantageous to have a less hard material at areas of impact or sudden stress change, such as at mounting surfaces or mechanical components subject to cantilevered loads. In some applications a combination of high surface hardness, to resist penetration and carry high load, and relative interior ductility (i.e. lower hardness) to allow some bending or flexure to occur, can be used to address a particular operating regime.
According to aspects illustrated herein, there is provided an inner ring for a bearing, including: a first portion having a first hardness; and a second portion including an axial end of the inner ring with an axial circumferential edge, a slot for receiving a mounting or fastening device, or a hole for receiving a mounting fastener, an inner portion axially between the first portion and the slot or hole, and an outer portion axially between the slot or hole and the axial circumferential edge. At least one of the inner or outer portions has a second hardness less than the first hardness.
According to aspects illustrated herein, there is provided a bearing assembly, including an inner race including: an inner ring including: a first portion having a first hardness; and a second portion including: an axial end of the inner ring with an axial circumferential edge; a slot for receiving a snap ring or other mounting device, or a hole for receiving a mounting fastener; an inner portion axially between the first portion and the slot or hole; and an outer portion axially between the slot or hole and the axial circumferential edge; an outer ring; and a plurality of rolling elements in contact with the first portion and the outer ring and radially disposed between the first portion and the outer ring. At least one of the inner or outer portions has a second hardness less than the first hardness.
According to aspects illustrated herein, there is provided a method of fabricating an inner race, including: forming the inner race; hardening the inner race to a first hardness; annealing a first portion of the inner race to have a second hardness, less than the first hardness, while leaving a second portion of the inner race with the first hardness; and forming in the first portion a slot for receiving a snap ring or other mounting device, or a hole for receiving a mounting fastener.
Various embodiments are disclosed, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, in which:
At the outset, it should be appreciated that like drawing numbers on different drawing views identify identical, or functionally similar, structural elements of the disclosure. It is to be understood that the disclosure as claimed is not limited to the disclosed aspects.
Furthermore, it is understood that this disclosure is not limited to the particular methodology, materials and modifications described and as such may, of course, vary. It is also understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to limit the scope of the present disclosure.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. It should be understood that any methods, devices or materials similar or equivalent to those described herein can be used in the practice or testing of the disclosure.
The adverbs “axially,” “radially,” and “circumferentially” are with respect to an orientation parallel to axis 81, radius 82, or circumference 83, respectively. The adverbs “axially,” “radially,” and “circumferentially” also are regarding orientation parallel to respective planes.
In an example embodiment, portion 108 includes surface 122 (not labeled in figure) receiving/contacting plurality of rolling elements 106 and having the first hardness.
Portion 118 includes surfaces 124 and 126, facing in opposite radial directions 128 and 130, respectively. Portion 118 includes interior portion 132 radially aligned with and radially disposed between surfaces 124 and 126. In an example embodiment, each of surfaces 124 and 126 has the second hardness. In an example embodiment, portion 132 has the second hardness. In an example embodiment, each of surfaces 124 and 126 and portion 132 has the second hardness.
Portion 110 includes radial portion 134 radially aligned with the slot. In an example embodiment, portion 134 has the second hardness. In an example embodiment, rolling elements 106 are spherical rollers. In an example embodiment, rolling elements 106 includes a group of spherical rollers 106A circumferentially disposed about inner ring 102 and a group of spherical rollers 106B circumferentially disposed about inner ring 102 and axially separated from spherical rollers 106A. No cage is shown in
In an example embodiment, portion 208 includes surface 222 receiving/contacting plurality of rolling elements 206 and having the first hardness. Portion 218 includes surfaces 224 and 226, facing in opposite radial directions 228 and 230, respectively. Portion 218 includes interior portion 232 radially aligned with and radially disposed between surfaces 224 and 226. In an example embodiment, each of surfaces 224 and 226 has the second hardness. In an example embodiment, portion 232 has the second hardness. In an example embodiment, each of surfaces 224 and 226 and portion 232 has the second hardness.
In an example embodiment, rolling elements 206 are rollers. In an example embodiment, rolling elements 206 includes a group of rollers 206A circumferentially disposed about inner ring 202 and a group of rollers 206B circumferentially disposed about inner ring 202 and axially separated from rollers 206A. No cage is shown in
The following should be viewed in light of
The first portion includes an axial end of the inner race, such as 112 or 212, with an axial circumferential edge, such as 114 or 214. The second portion includes a surface, such as surface 122 or 222, arranged to contact a plurality of rolling elements. The first portion includes surfaces, such as surfaces 124/126 or 224/226, facing in opposite radial directions having the second hardness. Forming the slot includes forming the slot in the one of the surfaces for the first portion. Forming the hole includes connecting the surfaces for the first portion with the hole.
In an example embodiment, the rolling elements are rollers. In an example embodiment, the rolling elements include a group of rollers, for example rollers 106A/206A, circumferentially disposed about the inner ring and a group of rollers, for example rollers 106B/206B, circumferentially disposed about the inner ring and axially separated from the first group of rollers.
Hardness testing was performed on inner race 102 along plane 140 (axially facing surface of axial end 114), plane 142 through slot 116, and plane 144 through portion 108 and surface 122. Sampling was performed at four evenly circumferentially spaced points in each plane (the second through fifth columns of
It should be understood that other hardnesses are possible for portions 108 and 110 and portions 208 and 210. It should be understood that other differences of hardnesses are possible between portions 108 and 110 and portions 208 and 210.
Thus, the annealing of portions 110/210, which results in the hardness of portions 110/210 being less than the hardness of portions 108/208 advantageously resolves the problem of cracking or weakening of portions 110/210 during operations on portions 110/210, such as forming slot 116 or hole 216, or mounting of snap ring 117. At the same time, the greater hardness of portions 108/208, desirable because of the contact of portions 108/208 with rolling elements 106/206, is preserved. Further, the lesser hardness of portions 110/210 reduces the likelihood of cracking or fracturing during mounting and removal of assembly 100/200, service/repair work on assembly 100/200, or operational use of assembly 100/200.
It will be appreciated that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims.
This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/814,418, filed Apr. 22, 2013, which application is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61814418 | Apr 2013 | US |
