|Publication number||USRE42445 E1|
|Application number||US 12/794,510|
|Publication date||Jun 14, 2011|
|Filing date||Jun 4, 2010|
|Priority date||May 26, 2006|
|Also published as||CN101454533A, EP2038506A2, EP2038506B1, US7647991, US20070272447, WO2007140010A2, WO2007140010A3|
|Publication number||12794510, 794510, US RE42445 E1, US RE42445E1, US-E1-RE42445, USRE42445 E1, USRE42445E1|
|Inventors||Floyd Felderhoff, Matthew R. Isbell, Rudolf C. Pessier|
|Original Assignee||Baker Hughes Incorporated|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (13), Classifications (7), Legal Events (1)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This claims priority to provisional application 60/808,874, filed May 26, 2007.
This invention relates in general to earth-boring bits, and in particular to rotating cone bits with cutting elements that are arranged to reduce tracking.
A roller cone earth-boring drill bit has a number of cones, typically three, each mounted rotatably to a bearing pin. Each cone rotates about its axis when the bit body rotates around the bit axis. The cones have rows of cutting elements, which may be teeth integrally formed in the cone metal, or tungsten carbide inserts pressed into mating holes in the cone metal.
Each cone will have an outermost or heel row near a gage surface of the cone and one or more inner rows. One or more of the cones will have cutting elements located near or on the nose of the cone. In some cases the inserts in the adjacent row closest to the heel row will be staggered or alternate with the inserts in the heel row.
The inner rows of each cone are arranged at different distances from the bit axis for cutting different portions of the borehole bottom. Normally, at least two of the cones will have heel rows that are located at substantially the same distance from the bit axis. Some of the adjacent rows may be approximately the same distance from the bit axis. When all three cones are rotated into a single section plane, these heel row inserts and some of the adjacent row inserts will superimpose or overlap at least partially on one another. The inner rows are normally spaced at different distances from the bit axis to cover the remaining portions of the borehole bottom.
When rows of inserts of different cones overlap each other, tracking can result. That is the inserts of the two or more cones in those rows tend to fall into the same holes in the borehole bottom, building up ridges on the bottom. These ridges are detrimental because they can contact the supporting metal of the cone, lower the load on the inserts, and cause wear.
In the prior art, steps are taken to reduce tracking. Usually, a bit designer tries to provide at least one of the heel rows with the maximum number of inserts because these rows engage more of the borehole bottom than any other rows. The maximum number is limited by the requirement of adequate supporting metal in the cone body. A typical approach to further reduce tracking is to increase the pitch in the overlapping heel row of another cone. The wider pitch, or distance between center lines of inserts, tends to break up the ridges that form between the impressions made by the more closely spaced heel row inserts. In addition, the adjacent row inserts are staggered with the wider pitch heel row. While workable, a greater pitch means fewer inserts in the adjacent row. This reduces the durability of the adjacent row and can result in even higher ridge build-up between the adjacent row inserts.
The earth boring bit of this invention has first, second and third cones rotatably mounted to the bit body. Each of the cones has a plurality of rows of cutting elements, including a heel row and an adjacent row The heel row of the first cone has at least equal the number of cutting elements as the heel rows of the other cones. The adjacent row of the second cone has at least 90 percent as many cutting elements as the heel row of the first cone. The heel row of the third cone has a pitch that is in the range from 20-50% greater than the heel row of the first cone to reduce tracking.
In the preferred embodiment, the pitches of the heel rows of the first and second cones are substantially the same. In one embodiment, the heel row and the adjacent row of the third cone are staggered relative to each other such that an outermost portion of the cutting elements of the adjacent row of the third cone is substantially as far from the bit axis as an innermost portion of the cutting elements of the heel row. The heel and adjacent rows of the second cone may also be staggered. Preferably the cutting elements of the adjacent row of the second cone protrude from supporting metal of the second cone substantially the same amount as the heel row of the first cone.
In the embodiment shown, the cutting elements comprise tungsten carbide inserts, each having a barrel that is pressed into a hole in the cone metal. Each of the first cone adjacent row cutting elements has a barrel diameter at least equal to the barrel diameter of the first cone heel row cutting elements. Preferably, the barrel diameters of the adjacent row cutting elements of all of the cones are at least equal to all of the heel row cutting elements.
Cones 11, 13 and 15 have a plurality of rows of cutting elements, which in this example comprise tungsten carbide inserts pressed into holes drilled in the metal of the cone body. Alternately, the cutting elements could comprise teeth machined in the exterior of the cone body. In the example of
First cone 11 also has a plurality of heel row inserts 19, which are located in a heel area adjoining the gage surface. One of the cones 11, 13, 15 will be provided with the maximum number of heel row inserts, which in this example, comprises heel row 19 of first cone 11. Heel row inserts 19 must have adequate supporting metal of the cone body between each insert 19. The supporting metal and the diameter of the barrel of each insert 19 determine the number of heel row inserts 19 that can be mounted on first cone 11. In this example, there are seventeen heel row inserts 19, but that number can vary.
First cone 11 has an adjacent row 21 of inserts, which is the closest row to the inserts of heel row 19. In this example, each portion of each adjacent row insert 21 is closer to bit axis 12 than any portion of heel row inserts 19. That is, they do not superimpose or overlap each other when rotated into a single sectional plane, as shown in
Like first cone 11, second cone 13 has two rows of gage inserts 27 that are staggered, but that arrangement could vary. Second cone 13 has a plurality of heel row inserts 29 and a plurality of adjacent row inserts 31. In this invention, since first cone 11 was selected to have the maximum number of heel row inserts, either second cone 13 or third cone 15 will be selected to have an adjacent row of inserts with 90% or more of the same number of inserts as first cone heel row 19. In this example, second cone 13 has that row of adjacent inserts 31. Also, second cone adjacent row inserts 31 may have the same diameter and cutting end protrusion as first cone heel row inserts 19.
Adjacent row 31 of second cone 13 is spaced much closer to its heel row 29 than adjacent row 21 is spaced to its heel row 19 of first cone 11. Preferably, second cone heel row inserts 29 and adjacent row inserts 31 are staggered relative to each other, with each adjacent row insert 31 being circumferentially between and farther inward than two of the heel row inserts 29. When rotated into a single plane as shown in
In order to provide adequate support metal for the large number of adjacent row inserts 31, in addition to the staggering, the size of heel row inserts 29 is considerably less than the size of adjacent row inserts 31. The diameters as well as the cutting ends of heel row inserts 29 are less than the diameter and cutting end protrusion of adjacent row inserts 31. Because second cone heel row inserts 29 and adjacent row inserts 31 are staggered, they normally have equal numbers. Second cone 13 also has inner row inserts 33 and one or more nose inserts 35. Inner row inserts 33 are located between adjacent row inserts 21 and inner row inserts 23 of first cone 11.
Third cone 15 has gage surface inserts 37, which in this example, are located in a single row. In addition, third cone 15 is configured to reduce tracking occurring between first cone heel row inserts 19, second cone heel row inserts 29 and third cone heel row inserts 39. The heel rows 19, 29 and 39 are all at the same distance from bit axis 12 in this embodiment. The number of first cone heel row inserts 19 and second cone heel row inserts 29 is either the same or within 90% of the same as mentioned, thus tracking could occur. To reduce tracking, third cone heel row 39 is provided with a substantially different pitch or distance between axes of inserts than the pitches of first cone heel row inserts 19 and second cone heel row inserts 29. The pitches in heel rows 19 and 29 do not differ significantly, and the pitch in first cone heel row 19 is a minimum amount possible, given the diameter and size of heel row inserts 19. Consequently, the pitch in third cone heel row 39 is made considerably larger, preferably 20 to 50% greater. First cone heel row 19 has at least equal the number of cutting elements as the heel rows 29, 39 of the other cones. In this example, there are only fourteen heel row inserts 39, versus seventeen heel row inserts 19 and sixteen heel row inserts 29. Stated another way, there are at least 20 to 50% more inserts in first cone heel row 19 than in third cone heel row 39. In this example, the difference is three divided by fourteen, which is 21.5% more.
In this example, third cone 15 has adjacent row inserts 41 that are staggered with heel row inserts 39 to enhance durability. The innermost portion of each heel row insert 39 is closer to bit axis 12 than the outermost portion of each adjacent row insert 41, creating an overlapping portion as shown in
Adjacent row inserts 41 may have the same diameter and cutting end protrusion as second cone adjacent row inserts 31 and first cone adjacent row inserts 21, and thus, they will also have a pitch that is 20-50% greater than between adjacent row inserts 31 of second cone 13. As shown in
When designing the cutting structure in accordance with this invention, the designer first selects one of the cones 11, 13, 15 to have a maximum number of heel row inserts given a desired protrusion and barrel diameter. In this embodiment, as mentioned, first cone 11 has the maximum number of heel row inserts in its heel row 19. The designer then selects another cone to have adjacent row inserts that are the same size and have at least 90% as many inserts as the maximum heel row 19. In this example, second cone 13 was provided with only one less adjacent row insert 31 than first cone heel row inserts 19. The designer then staggers heel row 29 on second cone 13 with adjacent row inserts 31. In order to provide supporting metal, heel row inserts 29 may be of smaller diameter and may have smaller cutting end protrusion than adjacent row inserts 31.
The designer then designs the third cone to break up tracking in the heel rows of the other cones. The designer does this by use of a third cone heel row 39 having a pitch 20-50% greater than the pitches of first cone heel row 19. In this example, heel row 39 has 21.4% fewer inserts than first cone heel row 19. Adjacent row 41 is staggered with heel row inserts 39, and therefore has also a greater pitch than adjacent row 31, thus breaking up tracking in the adjacent rows 31, 41.
The invention has significant advantages. Increasing the pitch in one of the heel rows resists tracking in the heel row and in one of the adjacent rows resists tracking in the adjacent rows. Providing at least 90 percent as many adjacent row cutting elements as the maximum number in the heel row provides durability for the adjacent row and resists ridge buildup.
While the invention has been shown in only one of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the invention. For example, although only cones with tungsten carbide inserts as cutting elements are shown, the cones could have cutting elements that comprise teeth machined from the body of the cone.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US2533259||Jun 28, 1946||Dec 12, 1950||Hughes Tool Co||Cluster tooth cutter|
|US2774571 *||Jul 6, 1954||Dec 18, 1956||Hughes Tool Co||Cone type well drill|
|US3018835||Nov 1, 1956||Jan 30, 1962||Reed Roller Bit Co||Drill bit for producing an irregular indentation pattern on the bottom of a well bore|
|US3134447||Jan 31, 1962||May 26, 1964||Hughes Tool Co||Rolling cone rock bit with wraparound spearpoints|
|US3223188 *||Oct 26, 1962||Dec 14, 1965||Chicago Pneumatic Tool Co||Roller cone rock bit|
|US4984643 *||Mar 21, 1990||Jan 15, 1991||Hughes Tool Company||Anti-balling earth boring bit|
|US5311958||Sep 23, 1992||May 17, 1994||Baker Hughes Incorporated||Earth-boring bit with an advantageous cutting structure|
|US6374930 *||Jun 8, 2000||Apr 23, 2002||Smith International, Inc.||Cutting structure for roller cone drill bits|
|US20040243367||May 26, 2004||Dec 2, 2004||Mcdonough Scott D.||Methods for evaluating cutting arrangements for drill bits and their application to roller cone drill bit designs|
|US20050096847 *||Jul 9, 2004||May 5, 2005||Smith International, Inc.||Methods for modeling, designing, and optimizing the performance of drilling tool assemblies|
|US20050167161||Jan 30, 2004||Aug 4, 2005||Aaron Anna V.||Anti-tracking earth boring bit with selected varied pitch for overbreak optimization and vibration reduction|
|US20060006003||Jul 7, 2004||Jan 12, 2006||Amardeep Singh||Multiple inserts of different geometry in a single row of a bit|
|GB2020715A||Title not available|
|U.S. Classification||175/341, 175/353, 175/376|
|International Classification||E21B10/00, E21B10/16|