US 3311181 A
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March 28, 1957 J. B. FOWLER BI-METAL DRILLING TOOTH Filed May 4, 1964 INVENTOR. Jdfl/l A. Fan 4 6? United States Patent 3,311,181 BI-METAL DRILLING TOOTH John B. Fowler, 1446 Malvern Ave., Los Angeles, Calif. 90006 Filed May 4, 1964, Ser. No. 364,427 Claims. (Cl. 175-410) This invention relates to drill teeth and drill heads particularly adaptable for drilling in rock, such as might be encountered in the drilling of oil wells or other bores in the earth.
It is an object of the invention to provide a tooth secured in or adapted to be secured in a drill bit matrix, wherein the tooth is formed from materials of diiferent degrees of hardness and wherein the harder and more brittle portion of the tooth is held and protected by a less hard and brittle portion, and wherein the less hard portion will erode under working conditions to a greater extent than the harder portion, thereby exposing successive portions of the harder material as the latter erodes to a lesser extent than the less hard portion.
Another object of the invention is to secure a drill tooth of the type mentioned in a suitable matrix, such as a rotary drill bit, wherein the hardness of the matrix is less or no greater than the hardness of the holding portion of the tooth, and the hardness of the matrix and holding portion is less than that of the working portion of the tooth.
Another object is to provide a tooth of the type described wherein it is adapted for mounting or mounted in a rotary bit matrix having a predetermined direction of rotation wherein the cross section of the harder working portion of the tooth diminishes in the direction opposite to that of the direction of rotation so that the exposed end of the working portion will erode or wear away to a greater extent in the diminished cross section, and wherein the end of the working face is eroded or worn away to a lesser degree than the portions of diminished cross section.
A further object of the invention is to provide a sectional tooth having different degrees of hardness wherein the two sections are divided along or parallel to the longitudinal axis of the tooth and its receiving socket in the matrix, or the tooth sections can be divided with a demarcation at an acute angle to the longitudinal axis of tooth and its socket, and wherein the less hard holding section secures the tooth in the socket with a wedging action.
The above and other objects will more fully appear from the following description in connection with the accompanying drawing, in which:
FIG. 1 is an end view of a tooth structure showing a portion of the drill bit matrix surrounding it;
FIG. 2 is a sectional detail of a portion of the drill bit matrix showing the tooth in side elevation;
FIGS. 3, 4, 5 and 6 are sectional details of portions of the drill bit matrix with the outer ends of a drill tooth illustrating the tooth from its first use to successive degrees of erosion or wear in use;
FIG. 7 is an end view of a modified form of drill tooth structure with a portion of the drill bit matrix surrounding it; and
FIG. 8 is a view similar to FIG. 2 of the modification shown in FIG. 7.
In the drawing there are shown portions of a drill bit matrix 10, the specific shape of which is not illustrated. It is contemplated that the drill bit matrix is a portion of a rotary drill bit of any desired shape. It should be understood, however, that the drill bit can, if desired, be similar to conventionally known core bits or drag bits with no moving parts, as distinguished from those with moving parts, such as cross roller rock bits.
Extending upwardly from the bottom of the matrix -10 is a socket 12, it being understood that any desired number of such sockets can be formed in the matrix. Located in the socket 12 is a tooth generally indicated at 14, and composed of a working section 16 and a holding section 13. The tooth 14 may be circular in cross section, although it is to be understood that other cross sectional shapes may be used.
The tooth 14 is shown split along its longitudinal axis and the working section 16 is relieved at 20 to expose the longitudinal edges 22 at each side of the fiat face 24 of the working section 16, which abuts the fiat face 26 of the holding section 18. As shown, the ends of the working and holding sections may be rounded.
The material of the working section 16 is of considerably greater hardness than that of the holding section 13, and the material of the matrix 10 is of no greater hardness than that of the holding section 18, it being preferred that the matrix be somewhat softer than the material of the holding section. Thus, when the tooth initially, and the tooth and matrix later, are eroded by abrasive contact with rock being drilled, the materials of the matrix and the holding section will erode more readily than that of the working section 16, and eifective portions of said working section will remain exposed for optimum cutting action.
It is contemplated that the working section of the tooth 16 be made of any of the known hard materials used in drilling. Such materials should be selected primarily for hardness, and secondarily for their transverse rupture and compressive strength. Among such materials are various tungsten carbides; borium carbide; diamond particles suspended in a tough metallic matrix; sintered corundum or other oxides of aluminum; silicon carbide or a hard ceramic material. The holding tooth section 18 and the matrix 10 can be of any suitable materials of relatively less hardness which are known in the drilling field and the metallurgical fields generally.
FIGS. 3 through 6 are illustrative of the manner in which my drilling tooth and the drill bit matrix may erode under use. FIG. 3 shows a new tooth which has not been used and therefore shows no erosion. The drill bit is retated in the direction of the arrow 28 in FIG. 3 with the holding section 18 of the tooth leading the working section 16, and the holding section 18 will, because of its lesser degree of hardness, erode to a greater degree than the working section 16. The holding and working sections 18 and 16 are held in their desired positions in the drill bit matrix 10 by cementing the two sections 18 and 16 together, as by sweating with silver and pressing the composite tooth into a hole 12 of close tolerance. The composite tooth may also be cemented in the hole or socket 12 and optionally the matrix can be heated to temporarily enlarge the hole for reception of the tooth.
As the tooth begins to erode, it will take a form such as illustrated in FIG. 4 with the outer end 30 of the holding section 18 eroded to a greater extent than the outer end 32 of the working section 16.
In FIG. 5 the tooth is shown eroded further with the outer end 30 of the tooth 18 eroded to a proportionally greater degree than the outer end 32 of the working section 16. In FIG. 5 the drill bit matrix 10 is shown eroded as at 34 in front of the holding section 18, and at 36, rearwardly of the working section 16. In FIG. 6 the tooth sections 18 and 16 have eroded further as has the matrix at 38 and 40. However, the erosion is not as great at 40 rearwardly of the working section 16 as it is at 38 forwardly of the holding section 18.
In FIGS. 7 and 8, there is shown a modified form of the tooth structure wherein a working section 42 and a holding section 44 have a demarcation which is at a slight angle to the longitudinal axis of the composite tooth and its hole or socket in the matrix 10. The working section 42 is of a greater cross section at its inner end 4-5, and the holding tooth section 44 is of lesser cross section at its inner end 48. Also, the holding section 44 is of less length than the working section 42, and said holding section is provided with a fiat outer end 50 by means of which it can be driven into the socket or hole 12 in the matrix 10 with a wedging action to securely hold the tooth sections in the socket 12. While the wedge-shaped holding section 44 does not initially extend outwardly as far as the working section 42, it does strengthen and provide support for that portion of the working section 42 that is buried in the matrix 10.
While I have shown and described the tooth construction as having the relatively flat leading face of the Working sections 16 and 42 facing in the direction of rotation, it should be understood that this face can be positioned at a slight angle to the direction of rotation in order to produce a shearing action on the formation cuttings to move them toward the perimeter of the hole.
It should be noted that because of the more rapid erosion of the holding section, the working section will always have a working face exposed to the formation being drilled, and due to the diminishing in cross section of the working section 16, the leading edge of the working face thereof will extend slightly deeper into the hole and formation than portions of the working section behind said working face.
The advantages of my invention are such that the tooth is competitive to bits having moving parts i.e., cones and bearings, and also to diamond bits in a wide variety of formations to be drilled.
It should of course be understood that various changes can be made in the form, details, arrangement and proportions of the structure, without departing from the spirit of the invention.
1. The combination with a rotary drill bit matrix having tooth-receiving socket means therein and adapted for working rotation in a predetermined direction, of a drill tooth with a following working section and a leading holding section with portions thereof secured in said socket means and other portions thereof extending from said socket means and the matrix, said holding section having a lesser degree of hardness than said working section.
2. The structure in claim 1, and said matrix having a degree of hardness no greater than that of said holding section.
3. The structure in claim 1, and said working section diminishing in cross section in the direction opposite to said predetermined direction of rotation of said drill bit matrix.
4. The structure in claim 1, and said working and holding sections being secured in said socket means and having a demarcation along the longitudinal axis of said socket means.
5. The structure in claim 1, and said working and holding sections having abutting longitudinal surfaces at slight angles to the longitudinal axis of said socket means, said working section increasing in cross section inwardly relative to said socket means, and said holding section decreasing in cross section inwardly relative to said socket means, the holding section being of less length than the working section and constituting a securing wedge for the working section.
References Cited by the Examiner UNITED STATES PATENTS 1,388,490 8/1921 Suman 175-413 X 2,101,376 12/1937 Voigtlander 175410 2,234,273 3/1941 Pennington 175379 X 2,575,438 11/1951 Alexander 175-410 X 2,969,122 1/1961 Steffes 1754l0 X 3,106,973 10/1963 Christensen 1754l0 X CHARLES E. OCONNELL, Primary Examiner.
N. C. BYERS, Assistant Examiner.
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