Roller Cone Bit Bearing, and Bearing Materials
A journal bearing element for use in forming a roller cone bit coupled to a bearing shaft to prevent circumferential sliding. Also included are material compositions of the journal bearing element. A journal bearing element is fixed in place relative to a head section and comprised of dense high purity powdered metal alloys with uniform micro-structure. A preferred material is comprised of a metal made of a carbon content of about 2.3% by weight, chromium of about 14% by weight, vanadium of about 9% by weight, and molybdenum at about 1% by weight.
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This application claims priority to and the benefit of co-pending U.S. Provisional Application Ser. No. 60/949,756, filed Jul. 13, 2007, the full disclosure of which is hereby incorporated by reference herein.
BACKGROUND1. Field of Invention
This disclosure relates to a journal bearing for a roller cone bit. Specifically, it concerns a set of bearing element materials, a method of manufacturing the bearing elements, and a manner of securing these bearing elements to a roller cone bit.
2. Description of Prior Art
Drill bits used in drilling of subterranean well bores typically comprise drag bits and roller cone bits. Roller cone bits typically comprise a body having legs extending downward and a head bearing extending from the leg towards the axis of the bit body. Frusto-conically shaped roller cones are rotatably mounted on each of these journals and are included with cutting teeth on the outer surface of these cones. Because of the high stresses incurred during drilling operations, the bearing mating surfaces within the bit require a bearing material or a surface treatment to sustain the loads and extend the bit life.
Traditionally, a journal bearing element 18 is disposed in a recess 19 circumferentially formed within the head section 14. The journal bearing element 18 accommodates the cone 12 rotation and the forces that the cone 12 may exert on the head section 14. The material used in forming the journal bearing element 18 varies; some are hard substances while others are soft, such as bronze and beryllium copper. In
The disclosure herein provides embodiments of a journal bearing for use in a roller cone bit and includes a manner of attaching a journal bearing element onto the head section of a drill bit. The journal bearing element included herein may prevent rotation of the journal bearing element. For example, when the bearing is used in conjunction with a roller cone, the sliding surfaces will be on the outer circumference of the journal bearing element and the inner surface of the roller cone. Methods of adhering the journal bearing element to the head include welding, brazing, gluing, the use of pins or dowels, an interference or press fit, splines transverse to the journal bearing circumference, and keys or key ways formed for insertion between the journal bearing element and the head section. In one embodiment, the journal bearing element is fixed in place relative to the head section and may optionally be comprised of dense high purity powdered metal alloys with uniform micro-structure. These powdered metal alloys may optionally be of a class that contains vanadium. A second optional class of materials would include a cobalt-chromium-tungsten alloy with high carbon content.
Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which:
While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF INVENTIONThe present invention will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the invention is therefore to be limited only by the scope of the appended claims.
The journal bearing element 28 may be affixed to the journal section 26 by means of brazing, gluing, soldering, or welding either individually or in combination with other coupling means as illustrated in
Another coupling device embodiment is presented in perspective partial sectional view in
An optional embodiment of a journal bearing element 28a is provided in a side sectional view in
The material used in making the journal bearing element 28 of the present device may be any suitable material; examples of materials include steels, stainless steels, and hard metal alloys including various Stellite® alloys. A material formed using a powdered metal manufacturing technique may be used for the journal bearing element 28. For example, a high vanadium content stainless steel powder could be used in conjunction with a powdered metal manufacturing technique to form a suitable bearing element. One specific example of this is an alloy referred to herein as S90V®, the alloy has carbon with a content of about 2.3% by weight of the alloy, a chromium content of about 14% by weight of the alloy, a vanadium content of about 9% by weight of the alloy, and molybdenum content of about 1% by weight of the alloy. Additionally, AISI 440C chemistries could be used to form a suitable head bearing element. For the purposes of the present disclosure, high vanadium content includes a composition, such as metal or metal powders having about 3% by weight or more of vanadium. Alternative values for vanadium content include 4%, 5%, 6%, 7%, 8% by weight, and all values of weight percentages between.
Another set of powered metal alloys for use in making the journal bearing herein described includes a cobalt-chromium-tungsten-carbon alloy. Optionally, the alloy may have a carbon content of about 1.2% by weight or greater.
The powder compositions described herein may utilize “master melt” compositions wherein all particles have essentially the same chemistry. Using a solid state consolidation technique, such as sintered-hot-isostatic-pressing, maintains homogeneity of the final product thereby producing a solid material without voids.
Other bit components could be made from the compositions described herein. Those components include any load bearing surface within the roller cone bit including thrust surfaces; additionally, pilot pin elements could also be manufactured using the compositions cited herein.
Claims
1. An earth boring bit comprising:
- a bit body;
- a leg section depending from the body;
- a bearing shaft extending from the leg having a circular bearing surface having an indentation formed substantially aligned with the axis of the bearing shaft;
- a coupling element disposed in the indentation;
- a journal bearing element on the bearing shaft and joined to the coupling element thereby coupling the journal bearing element to the bearing shaft.
2. The earth boring bit of claim 1, wherein the coupling element comprises a raised profile formed on the journal bearing element inner surface and a corresponding indentation in the bearing shaft formed to receive the raised profile therein for coupling engagement between the journal bearing and the bearing shaft.
3. The earth boring bit of claim 1, wherein the indentation comprises a first channel formed in the bearing shaft surface, the coupling element comprises a key member extending from the first channel into a second channel formed in the inner surface of the journal bearing element.
4. The earth boring bit of claim 1, wherein the journal bearing element comprises at least two separate members disposed on the bearing shaft.
5. The earth boring bit of claim 4, wherein the members substantially circumscribe the bearing shaft circumference.
6. The earth boring bit of claim 5, wherein one of the journal bearing elements is coupled with a coupling element thereby preventing circumferential movement of each bearing member with respect to the bearing surface.
7. The earth boring bit of claim 1 further comprising a cone mounted for rotation on the bearing shaft, the cone including a mating bearing surface for engagement with the journal bearing element outer surface.
8. The earth boring bit of claim 1, wherein coupling the journal bearing element to the bearing shaft prevents circumferential sliding of the journal bearing element around the bearing shaft.
9. An earth boring bit comprising:
- a bit body;
- a leg section depending from the body;
- a bearing shaft extending from the leg having a circular bearing surface; and
- a journal bearing element formed separately from the bit and adhered to the bearing shaft.
10. The earth boring bit of claim 9, wherein the journal bearing element is adhered to the bearing shaft by a process selected from the group consisting of soldering, brazing, and gluing.
11. The earth boring bit of claim 9, wherein the journal bearing element comprises at least two separate members disposed on the bearing shaft.
12. The earth boring bit of claim 11, wherein the members substantially circumscribe the bearing shaft circumference.
13. The earth boring bit of claim 12, wherein one of the journal bearing elements adhered to the bearing shaft prevents circumferential movement of each of the other bearing members.
14. The earth boring bit of claim 9 further comprising a cone mounted for rotation on the bearing shaft, the cone including a mating bearing surface for engagement with the journal bearing element outer surface.
15. The earth boring bit of claim 9, wherein adhering the journal bearing element to the bearing shaft prevents circumferential sliding of the journal bearing element around the bearing shaft.
16. An earth boring bit comprising:
- a bit body;
- a leg section depending from the body;
- a bearing shaft extending from the leg having a circular bearing surface; and
- a journal bearing element comprising an alloy, wherein the alloy includes at least about 3% by weight of vanadium.
17. The earth boring bit of claim 16 wherein the alloy is formed from a stainless steel powder.
18. The earth boring bit of claim 16 wherein the vanadium content exceeds about 6% by weight of the alloy.
19. The earth boring bit of claim 16 wherein the vanadium content is at least about 9% by weight of the alloy.
20. The earth boring bit of claim 16 wherein the alloy comprises carbon with a content of about 2.3% by weight of the alloy, chromium with a content of about 14% by weight of the alloy, vanadium with a content of about 9% by weight of the alloy, and molybdenum with a content of about 1% by weight of the alloy.
Type: Application
Filed: Jul 14, 2008
Publication Date: Jan 15, 2009
Applicant: Baker Hughes Incorporated (Houston, TX)
Inventors: Anton F. Zahradnik (Sugar Land, TX), Terry J. Koltermann (The Woodlands, TX), Aaron J. Dick (Houston, TX), Don Q. Nguyen (Houston, TX), Eric C. Sullivan (Houston, TX), Greg Ricks (Spring, TX)
Application Number: 12/172,364
International Classification: E21B 10/00 (20060101);