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US 8,418,332 B2Granted
Method of texturing a bearing surface of a roller cone rock bit
AssigneeVarel International Ind., L.P.
InventorXiaobin Lu
Life of this patent
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Abstract
Surface texturing is employed to modify the topography of one or more surfaces (radial or cylindrical) of the bearing system for a roller cone rock bit. The surface texturing results in a dimpled surface which retains additional lubricant helpful in reducing friction in the boundary and mixed lubrication regimes. Shot peening is disclosed as one method for texturing the desired surface.
Claims23
A method for building a drill bit, comprising:
- forming a journal bearing structure of a drill bit having a bearing system including at least one bearing surface;
- and
- surface texturing at least a portion of the bearing surface of the bearing system, wherein surface texturing comprises:
- exposing the portion of the bearing surface to a first shot peening action wherein the portion of the surface is bombarded at a first intensity level by first small spherical media of a first average size;
- exposing the same portion of the bearing surface to a subsequent second shot peening action wherein the same portion of the beating surface is bombarded at a second intensity level by second small spherical media of a second average size;
- and
- wherein the first and subsequent second shot peening actions create lubricant reservoirs on the same portion of the bearing surface, the lubricant reservoirs being adapted to contain lubricant for the bearing system;
- and
- wherein the first intensity level is greater than the second intensity level and the first average size is larger than the second average size.
6 more elements
A method of fabricating a drill bit, comprising:
- forming a shaft including a sealing surface and a bearing surface;
- forming a roller cone having an annular gland;
- rotatably mounting the roller cone to the shaft such that a bushing on the roller cone aligns with the bearing surface and the annular gland aligns with the sealing surface;
- shot peening in a first shot peening action the bearing surface of the shaft or an inner surface of the bushing at a first intensity level by a first small spherical media of a first average size;
- shot peening in a second subsequent shot peening action the bearing surface of the shaft or the inner surface of the bushing at a second intensity level by a second small spherical media of a second average size;
- wherein the first intensity level is greater than the second intensity level and the first average size is larger than the second average size;
- and
- wherein the first and second subsequent shot peening actions create lubricant reservoirs on the bearing surface of the shaft or the inner surface of the bushing, the lubricant reservoirs being adapted to contain lubricant.
5 more elements
A method of fabricating a drill bit, comprising:
- forming a shaft including a sealing surface and a bearing surface;
- forming a roller cone having an annular gland;
- rotatably mounting the roller cone to the shaft such that a bushing on the roller cone aligns with the bearing surface and the annular gland aligns with the sealing surface;
- forming a plurality of dimples by:
- shot peening in a first shot peening action the bearing surface of the shaft or an inner surface of the bushing at a first intensity level by a first small spherical media of a first average size;
- shot peening in a second subsequent shot peening action the bearing surface of the shaft or the inner surface of the bushing at a second intensity level by a second small spherical media of a second average size;
- wherein the first intensity level is greater than the second intensity level and the first average size is larger than the second average size;
- and
- wherein the first and second subsequent shot peening actions form lubricant reservoirs on the bearing surface of the shaft or the inner surface of the bushing, the lubricant reservoirs being adapted to contain lubricant for a drill bit;
- and wherein the plurality of dimples provide intermittent coverage.
7 more elements
Dependencies are inferred from the claim text.