Bearings are well known devices that enable relative movement two or more components. A variety of different bearing types are known and utilized on a regular basis. So-called “thrust bearings” and some embodiments of radial bearings conventionally include bearing surfaces that at least partially contact and move or slide relative to one another. Such bearing surfaces are conventionally prone to wear due to their interaction with one another and, as such, are formed from appropriate wear resistant materials. For example, such bearing surfaces may include a superhard material for resisting wear during use of the bearing. In one particular example, at least one or both of the bearing surfaces may be formed of a material comprising diamond (e.g., polycrystalline diamond).
As noted above, bearings may be used in numerous applications. In one example, bearings may be used subterranean drilling equipment. Such equipment may include drilling motors and drill bits having multiple components that move relative to one another, such as roller cones, and may be utilized for drilling boreholes into a subterranean formation, such as for oil or gas exploration. In a conventional downhole drilling motor, the motor is suspended at the lower end of a string of drill pipe comprising a series of pipe sections connected together at joints and supported from the surface. A rotary drill bit (e.g., a fixed cutter drill bit, roller cone drill bit, a reamer, etc.) may be supported below the drilling motor (via pipe sections, drill collars, or other structural members as known in the art) or may be directly connected to the downhole motor, if desired. Drilling fluid, which is commonly known as drilling mud, is circulated through the pipe string and the motor to generate torque within the motor to cause the rotary drill bit to rotate. Bearings are conventionally used to enable efficient relative rotation of the rotary bit and other components of the drill string.
Many types of bearings may be used in such a drill string assembly, including the bearings that may be employed by a rotary drill bit. One particular example includes radial bearings. In one embodiment, an inner and outer race are each provided with a plurality of superhard bearing elements (e.g., polycrystalline diamond elements). The races are positioned adjacent one another so that the bearing surfaces of the bearing elements contact one another during starting and stopping or overload conditions. In fluid bearings, the surfaces of the races do not contact during normal operation but, instead, are separated by a fluid film. As may be appreciated, geometry and configuration of the bearing elements of the races may be an important factor influencing the performance and life of such a bearing structure. Examples of some conventional radial bearing apparatuses are disclosed by U.S. Pat. Nos. 4,662,348, 4,729,440, 4,738,322, 4,756,631, and 4,764,036, the disclosures of each of which are incorporated, in their entireties, by this reference. Another example of a bearing used in drill string assembly includes a thrust bearing. A thrust bearing enables rotation between two adjacent components while also supporting a high level of axial thrust. Some examples of a thrust bearing assemblies are set forth in U.S. Pat. Nos. 7,552,782 and 7,870,913, the disclosures of each of which are incorporated, in their entireties, by this reference.
It is a continued desire within the industry to provide improved bearing elements and apparatuses including such elements.