Bearings – Rotary bearing – Roller drill bit
Reexamination Certificate
1999-10-01
2001-07-24
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Roller drill bit
C175S371000
Reexamination Certificate
active
06264367
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
FIELD OF THE INVENTION
The present invention relates generally to sealed bearing earth boring drill bits, such as rotary cone rock bits that utilize a fluid circulation medium. More particularly, the invention relates to such drill bits that have a dual seal arrangement for protecting internal bearing elements. Still more particularly, the present invention relates to a groove that allows pressurized drilling fluid to flow out from between a roller cone and its associated axle so as to optimize performance of the bit.
BACKGROUND OF THE INVENTION
During earth-drilling operations it is common to use a sealed bearing rotary cone drill bit. One common drill bit for use in an earthen annulus includes a bit body having at least one leg, the leg having at least one journal segment. A roller cone is rotatably mounted upon the leg journal segment and forms at least one bearing cavity therebetween. An annular primary seal is disposed between the leg and roller cone and is capable of sealing the bearing cavity. An annular secondary seal is disposed between the leg and roller cone and between the annular primary seal and the earthen annulus. The annular secondary seal is capable of substantially preventing the ingress of debris from the earthen annulus to the annular primary seal.
It is necessary to protect the bearing elements of the bit from contamination in order to sustain bit operability. In particular, it is desirable to isolate and protect the bearing elements of the bit, such as bearings, lubricant and bearing surfaces from earthen cuttings, mud and other debris in the drilling environment. Introduction into the bearing system of such contaminants leads to deterioration of the lubricant, bearings and bearing surfaces, causing undesirable wear and premature bit failure.
It is well known in the art to provide an annular seal around the bearing elements so as to prevent external contaminants from entering the bit through the annular opening and gap formed between each leg and its corresponding cone. These single seal arrangements, however, are known to be susceptible to leakage and premature wear due, for example, to the intrusion and abrasive effect of particles entering through the annular opening. When the single seal fails, the bearing elements become contaminated.
Dual seal arrangements have been developed that have an annular outer seal disposed around a primary inner seal for providing a second layer of protection against particles entering the annular opening. Generally, the outer seals of many prior art dual seal arrangements have provided insufficient protection around the primary seal. When the outer seal fails and allows particles or other contaminants to the primary seal, contamination of the bearing elements can occur as described above. Furthermore, various prior art dual seal arrangements require additional components or internal mechanisms that are susceptible to malfunction and/or increase the complexity of the bit and its manufacturing process.
Attempts have been made to prevent particles from entering the annular opening by directing pressurized drilling fluids, such as air, from within the drill bit out through the annular opening between the leg and cone. U.S. Pat. No. 4,102,419 discloses a rock bit with an inner metal sealing ring and a set of outer hardened mating surfaces between the leg and cone. Fluid is directed from inside the bit, past the inner metal sealing ring and the outer mating surfaces, and out through the annular opening so as to flush cuttings or other debris away from the inner seal. If the exiting fluid flow decreases or ceases, however, the outer mating surfaces may not effectively prevent the ingress of particles to the inner metal sealing ring due to the relative movement between the cone and leg during cone misalignment, thus exposing the inner metal sealing ring to contamination. Hence, for example, if the flow of drilling fluid is turned off during a pause in drilling operations, the particles generated during drilling will fall to the bottom of the hole, where the bit is likely to be sitting. Since there is no fluid flow out of the gap, there is a high probability that some particles will find their way into the annular gap.
It has also been proposed to include a groove in the cone between the inner primary seal and the annular opening. This groove directs fluid from inside the bit out through the annular opening to prevent the entry of particles from the borehole. U.S. Pat. Nos. 4,453,836 and 5,513,711 disclose variations on this concept. Nevertheless, the groove is subject to the same disadvantages, inasmuch as particles that enter the groove during time of reduced fluid flow tend to become trapped in the groove.
Hence, it is believed that the sealed bits of the prior art have significant disadvantages, and there remains a need for more effective configurations for protecting the bearing components of a sealed bearing rotary cone drill bit.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, an air groove is provided around part of the circumference of the interface between the leg and the cone. The air groove may preferably include one or more exit ports located at various positions. The exit port can be a drilled hole or can be an extension of the groove, either of which allows passage of particles from the groove to the outer surface of the bit leg. The air groove may also include a diversion plug positioned so as to mechanically dislodge or divert particles from the backface of the cone. The diversion plug can be energized or non-energized, and can be made from a variety of materials. If the groove includes an air exit port, it is preferred that the diversion plug be positioned in the groove. Alternatively, the plug can be located outside the air groove, virtually anywhere on the cone backface. Regardless of where it is positioned, the diversion plug cleans the backface.
The present invention comprises a combination of features and advantages that enable it to substantially advance the technology associated with sealed bearing drill bits. While the appended claims are not limited to the characteristics and advantages of the present invention described herein as well as additional features and benefits, various exemplary features of the invention will be readily apparent to those skilled in the art upon reading the following detailed description and referring to the accompanying drawings.
REFERENCES:
patent: 2960313 (1960-11-01), Goodwin
patent: 3268018 (1966-08-01), Neilson
patent: 3476446 (1969-11-01), Neilson
patent: 3746405 (1973-07-01), Welton
patent: 3921735 (1975-11-01), Dysart
patent: 3990525 (1976-11-01), Penny
patent: 4092054 (1978-05-01), Dye
patent: 4102419 (1978-07-01), Klima
patent: 4168868 (1979-09-01), Shields
patent: 4176848 (1979-12-01), Lafuze
patent: 4179003 (1979-12-01), Cooper et al.
patent: 4183417 (1980-01-01), Levefelt
patent: 4200343 (1980-04-01), Highsmith
patent: 4249622 (1981-02-01), Dysart
patent: 4252330 (1981-02-01), Crow
patent: 4253710 (1981-03-01), Goodman
patent: 4256351 (1981-03-01), Langford, Jr.
patent: 4277109 (1981-07-01), Crow
patent: 4284310 (1981-08-01), Olschewski et al.
patent: 4375242 (1983-03-01), Galle
patent: 4427307 (1984-01-01), Norlander et al.
patent: 4453836 (1984-06-01), Klima
patent: 4515228 (1985-05-01), Dolezal et al.
patent: 4552233 (1985-11-01), Klima
patent: 4629338 (1986-12-01), Ippolito
patent: 4641976 (1987-02-01), Kar
patent: 4657091 (1987-04-01), Higdon
patent: 4688651 (1987-08-01), Dysart
patent: 4722404 (1988-02-01), Evans
patent: 4722615 (1988-02-01), Bailey et al.
patent: 4756631 (1988-07-01), Jones
patent: 4762189 (1988-08-01), Tatum
patent: 4793719 (1988-12-01), Crockett et al.
patent: 4838365 (1989-06-01), Kotch
patent: 4875532 (1989-10-01), Langford, Jr.
patent: 4880068 (1989-11-01), Bronson
patent: 4934467 (1990-06-01), Langford, Jr.
patent: 4955440 (1990-09-01), Chavez
patent: 4981182 (1991-01-01), Dysart
patent: 5016719 (1991-05-01), White
patent: 5027
Didericksen Roger
Slaughter, Jr. Robert H.
Conley & Rose & Tayon P.C.
Hannon Thomas R.
Smith International Inc.
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