[0001] The present invention relates generally to drill bits, and, more specifically, relates
to drill bits having improved cutter configurations.
[0002] Drill bits presently known to the industry which utilize stationary cutting members
typically use either natural or synthetic diamonds as cutting elements, and are conventionally
known as "diamond bits". References herein to "diamond bits" or "diamond drill bits"
refer to all bits, for either drilling or coring, having primarily stationary cutting
members. Conventional diamond drill bits may have a variety of different types of
cutting surfaces, such as, for example polycrystalline diamond compact (PDC) cutters,
thermally stable diamond product (TSP) cutters, mosaic-type cutters and diamond impregnated
stud cutters. Mosaic cutters are typically formed of a plurality of geometrically-shaped
thermally stable diamond elements cooperatively arranged and bonded in a desired shape,
to form a unitary cutting surface.
[0003] On conventional bits, the diamond cutting surface is typically bonded to a supporting
member, which is then secured to a carrier member which facilitates attachment to
the drill bit. The cutting surface layer is preferably connected to the supporting
member such as through use of brazing or sintering. Preferably, the supporting member
and the carrier member will both be formed of a suitable hard or sintered metal, such
as, for example, tungsten carbide. The supporting member can be soldered or otherwise
connected, such as by form sintering or hot isostatic pressing, to the carrier member.
A discussion of such a conventional structure is found in U.S. Patent No. 4,498,549
issued February 12, 1985 to the inventor of the present application, and assigned
to the assignee of the present invention. The specification of U.S. Patent No. 4,498,549
is hereby incorporated herein for all purposes.
[0004] Additionally, drill bits may include more than one type of cutting member on a single
bit. Some types of cutting surfaces are better adapted to cut specific formations
than are others. For example, while large PDC-type cutters are extremely efficient
at cutting shales and other similarly soft formations, they are quickly broken or
abraded in hard formations. Other cutting surfaces, however, such as mosaic surfaces,
will cut through the harder formations satisfactorily. Accordingly, some relatively
recent diamond drill bit designs have included dual sets of cutting members, with
each set composed of cutting members having different types of cutting surfaces. With
bits of that type, for example, a first set of cutters is arranged on the bit to provide
essentially full face coverage across the face of the bit, and a second set of cutters,
of a different type, is arranged to provide coverage across at least a portion of
the bit face. An example of a bit of this type is disclosed in U.S. Patent applications
serial no. 173,943 filed March 28, 1988, in the names of Mark Jones and Mark Clench,
and assigned to the assignee of the present invention.
[0005] Such bits with dual cutter sets, while performing exceptionally well in some applications,
may not be feasible for use with all types of bits. For example, with bits having
cutting members with large cutting surfaces, such as one inch or greater in diameter,
it may not be feasible to include two sets of cutters on a single bit. Additionally,
even if the additional cutter set could be included on a single bit, the extra surface
area could interfere with chip removal, or could raise the total bottom hole surface
area contacting the formation to a level which would require an unacceptably high
weight-on-bit to cut the formation.
[0006] Accordingly, the present invention provides a new method and apparatus for including
composite cutting surfaces on a single drill bit, whereby the exposed face of the
cutting member may be maintained at a desired size, but whereby that face can be composed
of different cutting surfaces adapted to perform differently in the earth formations.
[0007] Drill bits in accordance with the present invention include at least some cutting
members which include cutting faces with multiple segments of cutting materials. Each
cutting member in accordance with the present invention will include at least two
segments, which are formed of at least two materials. The cutting material segments
will have exposed faces which cooperatively form the cutting face of the cutting member.
The segment faces will preferably lie in generally parallel planes, and most preferably
will be generally coplanar.
Figure 1 depicts a diamond drill bit having cutting members in accordance with the
present invention.
Figure 2 depicts that an isolated cutting member of the drill bit of Figure 1.
Figures 3A-F depict exemplary alternative cutting faces for a cutting member in accordance
with the present invention.
[0008] Referring now to the drawings in more detail, and particularly to Figure 1, therein
is depicted an exemplary embodiment of a drill bit 10 in accordance with the present
invention. Drill bit 10 includes a body section 12 which carries a plurality of cutting
members 16. Body 12 is preferably a molded component fabricated through conventional
metal matrix infiltration technology. Body section 12 is coupled to a shank 18 which
includes a threaded portion 20. Shank 18 and body 12 are preferably formed to be functionally
integral with one another. Drill bit 10 includes an internal recess (not illustrated),
through which hydraulic fluid will flow. A plurality of nozzles 22 are placed in body
12 to distribute hydraulic flow proximate the faces of cutting members 16.
[0009] Referring now also to Figure 2, therein is depicted an exemplary cutting member 16
in greater detail. The cutting face 24 of cutting member 16 includes two segments,
26 and 28. Cutting face segments 26 and 28 will each be formed of a layer of a cutting
material, but will be formed of different types of cutting material. For example,
segment 26 may be a PDC cutting layer, while segment 28 may be a TSP cutting layer.
Cutting face 24 of cutting member 16 may be formed of segments arranged in any of
a variety of conformities, and such face segments may be formed of any of a variety
suitable materials.
[0010] Referring now to Figures 3A-F, therein are depicted exemplary alternative configurations
and constructions for the cutting face of a cutting member 16 as depicted in Figures
1 and 2. Figure 3A depicts a cutting face 30 having a PDC face segment 32 and a mosaic
face segment 34. The two segments 32 and 34 are symmetrically arranged relative to
a vertical axis. Figure 3B depicts a face segment 36 having three generally vertically
extending faces 38, 40 and 42, symmetrically arranged about a central vertical diameter.
In the depicted embodiment, outer face segments 38 and 42 are of a first type of cutting
surface, while central face segment 40 is of a second type of cutting surface.
[0011] Figure 3C depicts a cutting face 44, which is similar in construction to cutting
face 36 of Figure 3B, with the exception that the face segments 46, 48 and 50 are
symmetrically disposed about a nonvertical diameter. Figure 3D depicts a two segment
cutting face 52, with face segments distributed on either side of a horizontal diameter.
Here again, upper segment 54 may be of a material such as a PDC layer, while lower
segment 56 may be of a different material, such as a TSP or mosaic material.
[0012] Figure 3E depicts an exemplary embodiment where the cutting face 58 is divided into
a plurality of quadrant face segments 60, 62, 64 and 66. These face segments 60, 62,
64 and 66 can be formed, for example, of two alternating cutting layer materials or
could all be formed of different cutting layer materials.
[0013] Figure 3F depicts an embodiment similar to that of Figures 3B and 3C, with the exception
that the three face segments of cutting face 68 are disposed symmetrically relative
to a horizontal diametrical axis.
[0014] Many modifications and variations may be made in the techniques and structures described
and illustrated herein without departing from the spirit and scope of the present
invention. For example, the multiple material cutting face segments may be formed
of virtually any appropriate material, and may be arranged in a variety of patterns
in addition to those described and depicted herein. Accordingly, the techniques and
structures described and illustrated herein are exemplary only and are not to be considered
as limitations on the scope of the present invention.
1. A drill bit, comprising:
a body member, and
a plurality of cutting members disposed on said body member, said cutting members
including cutting faces including multiple segments, said multiple cutting face segments
formed of at least two different materials.
2. The drill bit of claim 1, wherein said face segments of said cutting member face
lie in generally parallel planes.
3. The drill bit of claim 1, wherein said face segments of each cutting member face
are generally coplanar.
4. The drill bit of claim 1, wherein said cutting member faces each include at least
two face segments.
5. The drill bit of claim 1, wherein at least one of said face segments is formed
of a polycrystalline diamond compact surface.
6. The drill bit of claim 1, wherein at least one of said face segments comprises
a thermally stable diamond surface.
7. The drill bit of claim 1, wherein at least one of said face segments is formed
of a diamond mosaic surface.
8. A cutting member for drill bit, comprising:
a supporting structure; and
a cutting face secured to said supporting structure, said cutting face having at least
two segments, said cutting face segments formed of at least two materials.
9. The drill bit of claim 8, wherein said cutting member includes two said face segments.
10. The drill bit of claim 8, wherein said cutting face segments lie in generally
parallel planes.
11. The cutting member of claim 10, wherein said cutting face segments are generally
coplanar.
12. The cutting member of claim 8, wherein at least one of said segments is formed
of a polycrystalline diamond compact surface.
13. The cutting member of claim 8, wherein at least one of said segments is formed
of a thermally stable diamond surface.
14. The cutting member of claim 1, wherein at least one of said face segments is formed
of a diamond mosaic surface.