Boring or penetrating the earth – Bit or bit element – Rolling cutter bit or rolling cutter bit element
Reexamination Certificate
1999-01-25
2001-04-24
Bagnell, David (Department: 3672)
Boring or penetrating the earth
Bit or bit element
Rolling cutter bit or rolling cutter bit element
C384S095000
Reexamination Certificate
active
06220374
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to rotary cone drill bits and more specifically to a rotary cone drill bit with an enhanced thrust bearing flange.
BACKGROUND OF THE INVENTION
Various types of rotary drill bits or rock bits may be used to form a borehole in the earth. Examples of such rock bits include roller cone bits or rotary cone bits used in drilling oil and gas wells. A typical roller cone bit comprises a bit body with an upper portion adapted for connection to a drill string. A plurality of support arms, typically three, depend from the lower portion of the bit body with each support arm having a spindle or journal protruding radially inward and downward with respect to a projected rotational axis of the bit body.
A cutter cone assembly is generally mounted on each spindle or journal. Each cutter cone typically has a opening at its base, and a cavity extending from the base almost to the tip of the cutter cone. The cavity is formed such that it conforms with the associated journal. The cutter cone is supported rotatably on bearings acting between the exterior of the journal and the interior of the cutter cone assembly. The bearings in a typical rotary cone drill bit are heavily loaded during downhole drilling operations. In such drilling operations, the drill bit is rotated in a borehole, which causes the associate cutter cone assemblies to rotate on their respective journals. The drill bit typically operates at a low speed with heavy weight applied to the bit. This produces a high load on the associated bearings.
The drill bit typically includes a journal bushing. The journal bushing is positioned around the journal, and between the journal and the cutter cone assembly. The journal bushing is used to bear some of the forces transmitted between the journal and the cutter cone assembly, and to facilitate the rotation of the cutter cone assembly about the journal.
The journal also typically includes a thrust flange. The top of the thrust flange typically bears the load applied to the journal that is generally parallel to the axis of the journal about which the cutter cone rotates. Such forces are applied to the journal by the cutter cone assembly, and to the cutter cone assembly by the borehole wall. A thrust washer or bushing may be placed between the thrust flange and the cutter cone assembly to help bear this load. In addition, the thrust flange may also be used to contain the ball bearings. In such a situation, the thrust flange also must bear the load applied by the ball bearings when forces are acting to pull the cutter cone assembly off of its respective journal.
SUMMARY OF THE INVENTION
In accordance with teachings of the present invention, a roller cone drill bit having support arms with a spindle or journal extending from each support arm, and a respective cutter cone assembly rotatably mounted thereon is provided with an improved thrust flange.
The present invention allows the load-bearing capabilities of a drill bit thrust flange to be increased. The invention utilizes an enhanced thrust flange that is larger than the inside diameter of an associated drill bit journal bushing. The thrust flange may extend past the inside diameter of the journal bushing up to a distance equal to two times the thickness of the journal bushing. The invention may also utilize a thrust washer that is disposed adjacent the thrust flange to assist in bearing loads applied to the thrust flange.
Technical advantages of the present invention include an increased load carrying capacity of the thrust flange. This increased capacity improves the performance of the drill bit, and increases the drill bit's useful life by reducing the unit loading on its load-bearing surfaces. Another technical advantage of the present invention is that the enhanced thrust flange aids in maintaining the axis of the cutter cone concentric with the axis of the journal. This decreases wear on the drill bit, and thus increases its useful life.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions, and claims.
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“Baker Hughes Mining Tools Product Catalog,”Baker Hughes Mining Tools© 1991.
Bagnell David
Dresser Industries Inc.
Formby Betty
Groover Robert
Groover & Associates
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