U.S. patent application number 09/732074 was filed with the patent office on 2001-04-05 for reinforced abrasive-impregnated cutting elements, drill bits including same and methods.
Invention is credited to Lovato, Lorenzo G., Tibbitts, Gordon A..
Application Number | 20010000101 09/732074 |
Document ID | / |
Family ID | 22551149 |
Filed Date | 2001-04-05 |
United States Patent
Application |
20010000101 |
Kind Code |
A1 |
Lovato, Lorenzo G. ; et
al. |
April 5, 2001 |
Reinforced abrasive-impregnated cutting elements, drill bits
including same and methods
Abstract
A cutting element for use on a rotary-type earth boring drill
bit for drilling subterranean formations including a segment and a
support member. The support member is preferably fabricated from a
tough and ductile material, such as iron, an iron-based alloy,
nickel, a nickel-based alloy, copper, a copper-based alloy,
titanium, a titanium-based alloy, zirconium, a zirconium-based
alloy, silver, or a silver-based alloy. A bit attachment portion of
the support member is securable to a bit body. A segment-receiving
portion of the support member is disposable within a recess formed
in the segment to secure the segment to the bit body and support
the segment during use of the drill bit. Preferably, the segment is
fabricated from a hard continuous phase material that is
impregnated with a particulate abrasive material, such as natural
diamond, synthetic diamond, or cubic boron nitride. The continuous
phase material and abrasive material may be aggregated by
sintering, hot isostatic pressing, laser melting, or ion beam
melting.
Inventors: |
Lovato, Lorenzo G.; (Salt
Lake City, UT) ; Tibbitts, Gordon A.; (Salt Lake
City, UT) |
Correspondence
Address: |
TRASK BRITT
P.O. BOX 2550
SALT LAKE CITY
UT
84110
US
|
Family ID: |
22551149 |
Appl. No.: |
09/732074 |
Filed: |
December 7, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09732074 |
Dec 7, 2000 |
|
|
|
09154383 |
Sep 16, 1998 |
|
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Current U.S.
Class: |
175/425 |
Current CPC
Class: |
Y10T 428/12063 20150115;
Y10T 428/12167 20150115; E21B 10/5735 20130101 |
Class at
Publication: |
175/425 |
International
Class: |
E21B 010/00 |
Claims
What is claimed is:
1. A cutting element for use on an earth boring drill bit for
drilling subterranean formations, comprising: a member including a
segment-retaining portion and a drill bit attachment portion
attachable to a drill bit; and a segment comprising a continuous
phase impregnated with a particulate abrasive material, and secured
to said segment-retaining portion, at least a portion of at least
one of said member and said segment receiving at least a portion of
the other of said member and said segment.
2. The cutting element of claim 1, wherein said member comprises a
tough and ductile material.
3. The cutting element of claim 2, wherein said tough and ductile
material comprises iron, an iron-based alloy, nickel, a
nickel-based alloy, copper, a copper-based alloy, titanium, a
titanium-based alloy, zirconium, a zirconium-based alloy, silver,
or a silver-based alloy.
4. The cutting element of claim 1, wherein said continuous phase
comprises a metal carbide, a refractory metal alloy, a ceramic,
copper, a copper-based alloy, nickel, a nickel-based alloy, cobalt,
a cobalt-based alloy, iron, an iron-based alloy, silver, or a
silver-based alloy.
5. The cutting element of claim 1, wherein said particulate
abrasive material comprises at least one of natural diamond,
synthetic diamond, or cubic boron nitride.
6. The cutting element of claim 1, wherein said segment further
comprises a secondary particulate abrasive.
7. The cutting element of claim 1, wherein said segment comprises a
member-securing portion including a shape complementary to a shape
of said segment-receiving portion.
8. The cutting element of claim 1, wherein said segment is
cylindrical.
9. The cutting element of claim 1, wherein said member is
elongated.
10. The cutting element of claim 1, wherein said member includes a
recess configured to receive at least a portion of said
segment.
11. The cutting element of claim 1, wherein said segment is
configured to face in a direction of drilling of the earth boring
drill bit.
12. A rotary-type earth boring drill bit for drilling subterranean
formations, comprising: a bit body; and at least one cutting
element comprising: a member including a segment-retaining portion
and a drill bit attachment portion at least partially disposed
within said bit body; and a segment comprising a continuous phase
impregnated with particulate abrasive material, said segment
including a member-securing portion to which said segment-retaining
portion of said member is secured, at least a portion of at least
one of said member and said segment receiving at least a portion of
the other of said member and said segment.
13. The drill bit of claim 12, wherein said bit body comprises at
least one socket.
14. The drill bit of claim 13, wherein said at least one socket
comprises a shape complementary to said drill bit attachment
portion.
15. The drill bit of claim 12, wherein said member comprises iron,
an iron-based alloy, nickel, a nickel-based alloy, copper, a
copper-based alloy, titanium, a titanium-based alloy, zirconium, a
zirconium-based alloy, silver, or a silver-based alloy.
16. The drill bit of claim 15, wherein said bit body includes a
particulate-based matrix infiltrated with a binder.
17. The drill bit of claim 16, wherein at least a portion of said
binder secures said member to said bit body.
18. The drill bit of claim 12, wherein said member-securing portion
comprises a shape complimentary to said segment-retaining
portion.
19. The drill bit of claim 12, wherein said particulate abrasive
material comprises at least one of natural diamond, synthetic
diamond, or boron nitride.
20. The drill bit of claim 13, wherein said at least one socket
includes a countersink.
21. The drill bit of claim 20, wherein said countersink is
configured to receive said at least one cutting element in such a
manner that at least a portion of said segment is located below a
face of said bit body.
22. The drill bit of claim 10, comprising a plurality of cutting
elements in at least one of a radial arrangement, a spiral
arrangement, and a concentric arrangement.
23. A cutting element for use on an earth boring drill bit for
drilling subterranean formations, comprising: a segment comprising
a continuous phase impregnated with a particulate abrasive
material, said segment including at least one portion that receives
or is received by another member of the cutting element.
24. The cutting element of claim 23, wherein said continuous phase
comprises at least one of a metal carbide, a refractory metal
alloy, a ceramic, copper, a copper-based alloy, nickel, a
nickel-based alloy, cobalt, a cobalt-based alloy, iron, an
iron-based alloy, silver, and a silver-based alloy.
25. The cutting element of claim 23, wherein said segment is
configured to protrude from the earth boring drill bit.
26. The cutting element of claim 25, wherein said continuous phase
is configured to at least partially protrude from a blade of the
earth boring drill bit.
27. The cutting element of claim 25, wherein said continuous phase
is configured to at least partially protrude from a crown profile
of the earth boring drill bit.
28. A rotary-type earth boring drill bit for drilling subterranean
formations, comprising: a bit body; and at least one cutting
element secured to said bit body so as to protrude therefrom, said
at least one cutting element including a segment with a continuous
phase impregnated with a particulate abrasive material, said
segment including at least one portion that receives or is received
by another member of said at least one cutting element.
29. The rotary-type earth boring drill bit of claim 28, wherein
said at least one cutting element at least partially protrudes from
at least one of a crown profile of said bit body and a blade of
said bit body.
30. A cutting element for use on an earth boring drill bit for
drilling subterranean formations, comprising: a member including a
segment-retaining portion and a drill bit attachment portion
attachable to a drill bit; and a segment comprising a continuous
phase impregnated with a particulate abrasive material, and secured
to said segment-retaining portion.
31. The cutting element of claim 30, wherein said member comprises
a tough and ductile material.
32. The cutting element of claim 30, wherein said continuous phase
comprises a binder material.
33. The cutting element of claim 29, wherein said particulate
abrasive material comprises at least one of natural diamond,
synthetic diamond, or cubic boron nitride.
34. The cutting element of claim 29, wherein said segment further
comprises a secondary particulate abrasive.
35. The cutting element of claim 29, wherein said segment comprises
a member-securing portion including a shape complementary to a
shape of said segment-receiving portion.
Description
CROSS-REFERENCE TO RELATED APPLICATION
1. This application is a continuation of application Ser. No.
09/154,383, filed Sep. 16, 1998.
BACKGROUND OF THE INVENTION
2. 1. Field of the Invention
3. The present invention relates to cutting elements for use on
earth boring drill bits and bits so equipped. In particular, the
present invention relates to a cutting element which includes a
support which interconnects an abrasive-impregnated cutting
structure to the drill bit and mechanically reinforces the
impregnated segment. More specifically, the cutting element of the
present invention includes a tough and ductile support structure
which may be internal or external to the impregnated segment.
4. 2. Background of Related Art
5. Conventionally, earth boring drill bits with impregnated cutting
structures, commonly termed "segments," have been employed to bore
through very hard and abrasive formations, such as basalt, dolomite
and hard sandstone. As depicted by FIG. 1, the impregnated segments
16 of such drill bits are typically secured to the boring end 14,
which is typically termed the "face," of the bit body 12 of the
drill bit 10 in a generally radial fashion. Impregnated segments
may also be disposed concentrically over the face of the drill bit.
As the drill bit gradually grinds through a very hard and abrasive
formation, the outermost layer of the impregnated segments
containing abrasive particles (such as small diamonds, diamond
grit, or other super-abrasive particles such as cubic boron
nitride) wear and may fracture. Many conventional impregnated
segments are designed to release, or "shed", such diamonds or grit
in a controlled manner during use of the drill bit. As a layer of
diamonds or grit is shed from the face, underlying diamonds are
exposed as abrasive cuttings and the diamonds that have been shed
from the drill bit wear away the exposed continuous phase of the
segment in which the interior diamonds are dispersed, thereby
"resharpening" the bit until the entire diamond-impregnated portion
of the bit has been consumed. Thus, drill bits with
diamond-impregnated segments typically maintain a substantially
constant boring rate as long as diamonds remain exposed on such
segments.
6. Conventional impregnated segments typically carry the
super-abrasive particles in a continuous phase of a hard material,
such as tungsten carbide, a tungsten alloy, a metal carbide, a
refractory metal alloy, a ceramic, copper, a copper-based alloy,
nickel, a nickel-based alloy, cobalt, a cobalt-based alloy, iron,
an iron-based alloy, silver, or a silver-based alloy. Such
materials are, however, typically relatively brittle and may
fracture when subjected to the stresses of drilling. Accordingly,
when subjected to the high stresses of drilling, and particularly
impact stresses, the continuous phase of such impregnated segments
may break, resulting in the premature failure thereof and
potentially the premature failure of the bit upon which such
segments are carried. Thus, drilling times and costs are increased
by premature failure of conventional impregnated segments, as it is
necessary to remove the drill string from the bore hole, replace
the entire drill bit, and reintroduce the drill string into the
bore hole.
7. U.S. Pat. No. 4,234,048 (the "'048 patent"), which issued to
David S. Rowley on Nov. 18, 1980, discloses an exemplary drill bit
that bears diamond-impregnated segments on the crown thereof.
Typically, the impregnated segments of such drill bits are C-shaped
or hemispherically shaped, somewhat flat, and arranged somewhat
radially around the crown of the drill bit. Each impregnated
segment typically extends from the inner cone of the drill bit,
over the nose and up the bit face to the gage. The impregnated
segments may be attached directly to the drill bit during
fabrication, or partially disposed within a slot or channel formed
into the crown and secured to the drill bit by brazing. When
attached to the crown of a drill bit, conventional impregnated
segments have a relatively low profile (i.e., shallow recesses
between adjacent segments) relative to the bit face and a footprint
that covers the majority of the drill bit surface from the nose to
the gage. The low profile is typically required due to the
relatively brittle materials from which the continuous phases of
conventional impregnated segments are formed. Similarly, the
generally semicircular shape of conventional impregnated segments
and their somewhat radial arrangement around the crown of a bit
body are required to prevent the breakage and premature wear of
such impregnated segments due to the hard but relatively brittle
continuous phase materials thereof. The large "footprint" of
conventional impregnated segment-bearing drill bits is typically
necessary to provide a sufficient amount of cutting material on the
face of the bit. To some extent, the conventionally required
semicircular shape of impregnated segments has also prohibited the
use of alternative impregnated segment shapes, drill bit designs,
and arrangements of impregnated segments on drill bits, which could
otherwise optimize drilling rates and reduce the rate of bit wear
and failure.
8. Because of the low profile or exposure and large surface area
footprint of conventional impregnated segments, very little
clearance exists between the face of the drill bit and the drilled
formation during use of the drill bit upon which such segments are
carried. Consequently, the build-up of formation fines, such as
rock flour, on the impregnated segments may prevent contact of the
impregnated segments with the interior surface of the bore hole,
and may reduce the depth of cut of the drill bit. Moreover, due to
the large surface area footprint and the low profile of impregnated
segments on conventional drill bits, the hydraulics of such drill
bits cannot be employed to remove formation fines therefrom or to
cool the segments. Therefore, the rate of drilling and the amount
of weight on bit that may be employed on the drill bit may be
decreased, while the rate of wear is undesirably high, and failure
of the drill bit may occur.
9. Thus, there is a need for an impregnated segment which will
better resist breakage during drilling of very hard and abrasive
formations, and which may be optimally designed and arranged upon a
drill bit. There is also a need for impregnated segments which may
be arranged on a drill bit to facilitate the use of drill bit
hydraulics to remove formation fines from the impregnated surfaces
of the drill bit and which facilitate the use of alternative drill
bit designs.
BRIEF SUMMARY OF THE INVENTION
10. The cutting elements of the present invention address the
foregoing needs.
11. The cutting elements of the present invention include an
impregnated cutting structure having an associated support member,
which support member is securable to an earth boring rotary-type
drill bit body, and provides mechanical support to the cutting
structure.
12. The impregnated segment includes a continuous phase material
impregnated with particles of an abrasive material. Preferably, the
continuous phase material includes a hard, erosion- and
wear-resistant material, such as metal carbide, a refractory metal
alloy, a ceramic, copper, a copper-based alloy, nickel, a
nickel-based alloy, cobalt, a cobalt-based alloy, iron, an
iron-based alloy, silver, or a silver-based alloy. The abrasive
material with which the continuous phase material is impregnated
preferably comprises a hard, abrasive and abrasion-resistant
material, and most preferably a super-abrasive material such as
natural diamond, synthetic diamond, or cubic boron nitride. The
impregnated segment may include more than one type of abrasive
material, as well as one or more sizes of abrasive material
particles. The impregnated segment is fabricated by mixing the
continuous phase material with the abrasive material and employing
known processes, such as hot isostatic pressing, sintering, laser
melting, or ion beam melting, to fuse the mixture into a cutting
structure of desired shape. The impregnated segment may be
fabricated directly onto a segment-retaining portion, or
segment-retaining surface, of the support member, or attached
thereto by known techniques, such as brazing or mechanical
affixation.
13. The support member of the inventive cutting element, which is
preferably fabricated from a tough and ductile material, such as
iron, an iron-based alloy, nickel, a nickel-based alloy, copper, a
copper-based alloy, titanium, a titanium-based alloy, zirconium, a
zirconium-based alloy, silver, or a silver-based alloy, and other
tough and ductile materials that will withstand elevated
temperatures, such as are experienced during sintering, brazing and
bit furnacing, includes a segment-retaining portion and a drill bit
attachment portion. The segment-retaining portion of the support
member may be secured to the impregnated segment. The attachment
portion of the support member is preferably insertable into a
socket of a bit body and may be secured therein by brazing to the
bit body, mechanical affixation, or other known processes.
Alternatively, the support member may be secured to the bit body by
integral infiltration therewith during fabrication thereof.
14. When attached to a drill bit, a portion of the impregnated
segment may be recessed within the socket or a countersink
thereabout and, therefore, protected by the bit face adjacent the
peripheral edge of the socket that retains the cutting element.
Such recessing of the impregnated segment may provide additional
support to the impregnated segment and prevent dislodging of the
impregnated segment from the support member by shielding the
interface of the impregnated segment and the support member from
drilling fluid and abrasive, erosive debris that may otherwise come
into contact therewith during drilling.
15. Since the segment-retaining portion of the tough and ductile
support member is preferably secured to the impregnated segment,
the support member supports the impregnated segment during use of
the drill bit. Accordingly, the impregnated segment may extend from
the face of the drill bit body a greater distance than many
conventional impregnated segments (i.e., the inventive impregnated
segment may have an increased exposure relative to that of
conventional impregnated segments). Thus, the segment-support
member configuration of the cutting element of the present
invention facilitates the use of alternatively shaped impregnated
segments on a drill bit, alternative impregnated segment
orientations on the drill bit, and differently shaped drill bits
for boring through very hard and abrasive formations.
16. Other advantages of the present invention will become apparent
to those of ordinary skill in the art through a consideration of
the ensuing description, the drawings and the appended claims.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
17. FIG. 1 is an inverted side plan view of a conventional drill
bit with impregnated segments disposed in a generally radial
fashion over the crown of the drill bit;
18. FIG. 2 is a perspective view of a first embodiment of a cutting
element according to the present invention, including a C-shaped
impregnated segment and a support member disposed in a concave
portion of the impregnated segment;
19. FIGS. 2a-2c are perspective views of variations of the cutting
element of FIG. 2;
20. FIG. 3 is a partial inverted side plan view of a drill bit
which includes the cutting elements of FIG. 2;
21. FIG. 4 is a frontal perspective view of another embodiment of
the cutting element of the present invention, wherein the support
member is an elongated member having an impregnated segment
disposed on a portion thereof;
22. FIG. 5 is a cross-section taken along line 5--5 of FIG. 4;
23. FIG. 6 is a perspective view of a variation of the cutting
element of FIGS. 4 and 5, wherein the support member and
impregnated segment each include a non-circular cross-section;
24. FIG. 7 is a partial vertical cross-sectional view of a bit
body, which illustrates the member of FIGS. 4 and 5 disposed in a
socket of the bit body with the entire impregnated segment being
located externally relative to the bit face;
25. FIG. 8 is a partial vertical cross-sectional view of a bit
body, which illustrates the support member of FIGS. 4 and 5
disposed in a socket of the bit body and a portion of the
impregnated segment disposed in a countersink formed about the
socket;
26. FIG. 9 is a frontal perspective view of another embodiment of
the cutting element of the present invention, wherein the support
member is an elongated member having an impregnated segment
disposed on a portion thereof such that the periphery of the
impregnated segment is substantially flush with the exposed
periphery of the support member;
27. FIG.10 is a cross-section taken along line 10--10 of FIG.
9;
28. FIG. 11 is a partial vertical cross-sectional view of a bit
body, which illustrates the support member of FIGS. 9 and 10
disposed in a socket of the bit body with the entire impregnated
segment being located externally relative to the bit face;
29. FIG. 12 is a partial vertical cross-sectional view of a bit
body, which illustrates the support member of FIGS. 9 and 10
disposed in a socket of the bit body with a portion of the
impregnated segment being located within the socket;
30. FIGS. 13-15 are cross-sectional views of alternative
embodiments of the cutting element, wherein the cutting surface
protrudes from the drill bit;
31. FIG. 16 is a cross-sectional view of another embodiment of the
cutting element, wherein the impregnated segment faces the
direction of rotation of the drill bit;
32. FIG. 16a is a top plan view of a variation of the embodiment of
FIG. 16;
33. FIG. 17 is a cross-sectional view of another embodiment of the
cutting element, wherein the support member includes a recess for
receiving the impregnated segment or a portion thereof;
34. FIG. 18 is an inverted perspective view of a drill bit which
carries the cutting elements of FIGS. 4 and 5 or of FIGS. 9 and
10;
35. FIGS. 19-21 are inverted perspective views which each
illustrate a variation of the drill bit of FIG. 18;
36. FIGS. 22-24 illustrate exemplary increased surface area
interfaces between an impregnated segment and an associated support
member;
37. FIG. 25 is a frontal perspective view of an arcuate shaped
segment and support member according to the present invention;
and
38. FIG. 26 is an bottom view of a drill bit including the arcuate
shaped segments and support members of FIG. 25 disposed thereabout
in a circumferential configuration.
DETAILED DESCRIPTION OF THE INVENTION
39. With reference to FIG. 2, a first embodiment of a cutting
element 30 according to the present invention is depicted. Cutting
element 30 includes a substantially C-shaped impregnated segment 32
which defines a recess 34, which is also referred to as a
member-securing portion or surface, in the concave portion thereof.
Recess 34 is configured to receive a complementarily shaped
segment-receiving portion 38 of a support member 36, which is also
referred to as a member. A portion of support member 36 lying
within the curve of the "C" of segment 32 is referred to as a bit
attachment portion 40.
40. Impregnated segment 32 preferably includes a continuous phase,
which may be a metallic phase, throughout which an abrasive,
abrasion-resistant material is dispersed, as known in the art.
Preferably, a continuous phase material is a hard,
erosion-resistant and wear-resistant material. Continuous phase
materials that are useful in impregnated segment 32 include,
without limitation, metal carbides (e.g., tungsten carbide,
titanium carbide, silicon carbide, etc.), refractory metal alloys,
ceramics, copper, copper-based alloys, nickel, nickel-based alloys,
cobalt, cobalt-based alloys, iron, iron-based alloys, silver, or
silver-based alloys.
41. Abrasive materials that are useful in impregnated segment 32
and provide a cutting structure within the segment are preferably
hard, abrasive and abrasion-resistant materials. Exemplary abrasive
materials with which the continuous phase material of impregnated
segment 32 may be impregnated include, but are not limited to,
super-abrasives, such as natural diamonds, synthetic diamonds,
cubic boron nitride, as well as other hard, abrasive and
abrasion-resistant materials. The abrasive material may be coated
with a single or multiple layers of metal coatings, as known in the
art and disclosed in U.S. Pat. Nos. 4,943,488 and 5,049,164, the
disclosures of each of which are hereby incorporated by reference
in their entirety. Such metal coatings are known to increase the
strength with which the abrasive material bonds to the continuous
phase material. The abrasive material may be of a substantially
uniform particle size, which may be measured in carats or mesh
size, or may include particles of various sizes. Similarly, the
continuous phase material may be impregnated with a combination of
various types of abrasive materials. Impregnated segment 32 may
also include secondary abrasives, such as ceramics and aluminum
oxides.
42. The continuous phase material and abrasive material of
impregnated segments 32 are preferably aggregated into a desired
shape by known processes that bond the continuous phase material
and the particles of abrasive material together, such as sintering,
hot isostatic pressing, laser melting, or ion beam melting.
Impregnated segment 32 may be fabricated with a recess or
member-securing portion that is shaped to receive the
segment-receiving portion 38 of support member 36 and subsequently
secured thereto by known techniques, such as by the use of
adhesives, brazing, or mechanical affixation. Alternatively,
impregnated segment 32 may be formed directly onto support member
36 wherein impregnated segment 32 is simultaneously secured to
support member 36.
43. Support member 36 is preferably fabricated from a tough and
ductile material that will withstand the forces that are
encountered by the drill bit while employed in the drilling of
subterranean formations. Exemplary materials that may be used to
fabricate support member 36 include, without limitation, iron, an
iron-based alloy, nickel, a nickel-based alloy, copper, a
copper-based alloy, titanium, a titanium-based alloy, zirconium, a
zirconium-based alloy, silver, or a silver-based alloy, and other
tough and ductile materials that will withstand elevated
temperatures, such as are experienced during sintering, brazing and
bit furnacing. Support member 36 may be manufactured by techniques
known in the art, such as by sintering, casting, forging or
machining.
44. FIGS. 2a-2c illustrate exemplary variations of the cutting
element 30 of FIG. 2 that are also within the scope of the present
invention. FIG. 2a shows a cutting element 30' that includes an
impregnated segment 32' having an L-shaped cross section.
Preferably, when disposed on a drill bit, the portion of
impregnated segment 32' that extends over the side of support
member 36' faces in the same direction that the bit rotates. FIG.
2b shows a cutting element 30" including an impregnated segment 32"
similar to that shown in FIG. 2a, but having a substantially
triangular cross section. Again, the exposed side of impregnated
segment 32" faces in the direction of bit rotation. FIG. 2c
illustrates another variation, in which the cutting element 30'"
includes an impregnated segment 32'" that is secured to a single
major surface of the support member 36'".
45. Referring to FIG. 3, a drill bit 48 is shown which includes
several cutting elements 30 disposed in a generally radial fashion
about the crown 52 of the bit 48. Preferably, the bit attachment
portion 40 of the support member 36 (see FIG. 2) of each cutting
element 30 is disposed within a slot 56 that is formed into crown
52 of drill bit 48 and shaped complementarily to bit attachment
portion 40. Slots 56 may also be shaped to receive lower portions
of impregnated segments 32, such that lower portions of impregnated
segments 32 are recessed beneath and external to the bit face 54 so
that the interfaces between segments 32 and support members 36 are
protected from the drilling fluid and debris that are present in
the bore hole during drilling.
46. The bit attachment portion 40 (see FIG. 2) of each cutting
element 30 is secured to crown 52 by known techniques, such as by
the use of adhesives, brazing, or mechanical affixation.
Alternatively, and particularly when support member 36 is a
particulate-based structure (e.g., a structure comprised of
sintered steel), bit attachment portion 40 of each cutting element
may be disposed within a mass of particulate-based matrix material
used to form bit body 50, and the matrix material and support
members integrally infiltrated, as known in the art. During
infiltration, molten binder, typically a copper-based alloy,
imbibes between the particles of the bit body 50 matrix and support
member 36 by capillary action, by gravity, or under pressure. As
the binder solidifies, it binds particles of the matrix to one
another to form bit body 50 and fixes cutting elements 30 to bit
body 50. As another alternative, a particulate-based support member
36 and its associated segment 32 may be infiltrated independently
of the bit body, prior to assembly with or securing of same to
crown 52.
47. With continued reference to FIG. 3, due to the insertion of
segment-receiving portion 38 of support member 36 into recess 34
(see FIG. 2) of impregnated segment 32, support member 36 braces
and somewhat resiliently supports impregnated segment 32 against
both normal and torsional rotational stresses encountered during
drilling. Thus, support member 36 may reduce the likelihood that
impregnated segment 32 will fracture or otherwise be damaged during
drilling. Accordingly, support member 36 facilitates a higher
profile or exposure of cutting elements 30 relative to bit face 54
than conventional drill bits that carry impregnated segments (see
FIG. 1). Thus, a greater volume and depth of space may exist
between adjacent cutting elements 30 on drill bit 48 than between
conventional impregnated segments that are carried upon a similarly
configured drill bit. This increased volume and depth of space
between adjacent cutting elements 30 improves the hydraulic
performance of drill bit 48 relative to conventional drill bits
which carry impregnated segments. Consequently, cutting elements 30
facilitate an increased rate of debris removal from the drilling
surface. Similarly, more drilling fluid may be supplied to the
impregnated segments, which facilitates a reduction in the amount
of potentially damaging friction generated at crown 52, as well as
increases the rate at which the impregnated segments are cooled,
reducing the likelihood of damaging the segments and potentially
decreasing their rate of wear due to heat-induced degradation of
the segment continuous phase material.
48. FIGS. 4 and 5 illustrate another embodiment of the cutting
element 60 of the present invention, which includes a post-like
support member 66, which is also referred to as a member, with an
impregnated segment 62 disposed on a portion thereof. Preferably,
impregnated segment 62 is fabricated from a continuous phase
material that is impregnated with an abrasive material, such as the
continuous phase materials and abrasive materials described above
in reference to the impregnated segment 32 of cutting element 30,
shown in FIG. 2. The continuous phase material and abrasive
material of impregnated segment 62 may also be aggregated by known
processes, such as sintering, hot isostatic pressing, laser
melting, or ion beam melting. Impregnated segment 62 has a circular
cross section, taken transverse to a longitudinal axis 72 of
cutting element 60, and includes a receptacle 64 formed in a bottom
surface thereof.
49. Support member 66 may be an elongated structure which includes
a segment-receiving portion 68 at one end thereof and a bit
attachment portion 70 at the opposite end thereof.
Segment-receiving portion 68 is preferably shaped complementarily
to receptacle 64 of impregnated segment 62 so that it may receive
and secure the impregnated segment or impregnated segment 62 may be
formed over support member 66. Support member 66 may be fabricated
from the same material and processes that may be employed to
fabricate support member 36, which is shown in FIG. 2. Similarly,
known techniques, such as those described above in reference to
FIG. 2, may be employed to secure impregnated segment 62 to support
member 66.
50. FIG. 6 illustrates a variation of the present embodiment of the
cutting element 60', which includes a rectangular-shaped
impregnated segment 62' attached to a portion of a support member
66' of rectangular cross section taken transverse to a longitudinal
axis 72' of the cutting element. Similarly, the impregnated
segments and support members of other variations of the present
embodiment of the cutting element may have other, non-cylindrical
shapes.
51. As shown in FIG. 7, bit attachment portion 70 of support member
66 may be disposed within a socket 82 formed in a face 84 of a bit
body 80 by similar techniques to those described above in reference
to FIG. 3. Preferably, socket 82 is shaped complementarily to bit
attachment portion 70 in order to receive cutting element 60 and
securely attach same to bit body 80. In FIG. 7, cutting elements 60
are arranged on bit face 84 such that impregnated segments 62 are
located entirely external relative to the bit face, and the bottom
surface of the impregnated segments may abut the bit face.
52. Alternatively, as shown in FIG. 8, each socket 82 may include a
countersink 83 around the opening thereof, within which a lower
portion of impregnated segment 62 may be disposed as a support
member 66 is positioned within socket 82 and cutting element 60 is
attached to bit body 80. When a portion of impregnated segments 62
is located below bit face 84, the interface between impregnated
segment 62 and support member 66 is shielded from the drilling
surface, debris and drilling fluid that may otherwise penetrate the
interface and dislocate impregnated segment 62 from support member
66 by erosion or abrasion.
53. Turning now to FIGS. 9 and 10, another embodiment of the
inventive cutting element 100 is shown, which includes an
impregnated segment 102 disposed on a portion of a support member
106. Impregnated segment 102 and support member 106 each have a
circular cross section, taken transverse to a longitudinal axis 112
of cutting element 100. Impregnated segment 102 includes a recess
104, which is also referred to as a member-securing portion, formed
in the bottom thereof, which is configured to interconnect with a
complementarily shaped segment-receiving portion 108 of support
member 106. Support member 106 also includes a bit attachment
portion 110 opposite segment-receiving portion 108. Preferably,
segment-receiving portion 108 has a smaller circumference than bit
attachment portion 110 and, when viewed from the top thereof, is
concentrically positioned upon bit attachment portion 110.
54. Support member 106 and impregnated segment 102 may be
interconnected by known techniques such as by the use of adhesives,
brazing, mechanical affixation, or by aggregating the continuous
phase material and abrasive material impregnated segment 102
directly onto segment-receiving portion 108 of support member
106.
55. When impregnated segment 102 and support member 106 are
interconnected, a peripheral interface 105 is defined between the
impregnated segment and support member. Preferably, impregnated
segment 102 and bit attachment portion 110 of support member 106
may each have substantially constant cross-sectional (taken
transverse to longitudinal axis 112) peripheral circumferences
along the heights thereof. The cross-sectional peripheral
circumferences of impregnated segment 102 and bit attachment
portion 110 are substantially the same. Thus, the edges of
impregnated segment 102 and support member 106 at peripheral
interface 105 abut each other in a substantially flush arrangement,
imparting cutting element 100 with a substantially cylindrical
appearance.
56. Preferably, impregnated segment 102 is fabricated from a
continuous phase material that is impregnated with an abrasive
material, such as the continuous phase materials and abrasive
materials described above in reference to the impregnated segment
32 of cutting element 30, shown in FIG. 2. Similarly, the
continuous phase material and abrasive material of impregnated
segment 102 may be aggregated by known processes, such as
sintering, hot isostatic pressing, laser melting, or ion beam
melting. Similarly, support member 106 is fabricated from the same
materials and by the same techniques that are described above in
reference to support member 36, which is also shown in FIG. 2.
57. Referring now to FIG. 11, bit attachment portion 110 of each
support member 106 may be disposed within a socket 82 formed in a
face 84 of a bit body 80. Preferably, sockets 82 are shaped
complementarily to a corresponding bit attachment portion 110 so as
to securely receive cutting element 100. Cutting element 100 may be
secured to bit body 80 by techniques such as those described above
in reference to FIG. 3. The depth of sockets 82 may be such that,
when cutting elements 100 are attached to bit body 80, impregnated
segments 102 are located entirely exterior of bit face 84.
Alternatively, as shown in FIG. 12, deeper sockets 82' may receive
a lower portion of impregnated segments 102, positioning the lower
portion below bit face 84, and thereby shielding peripheral
interface 105 from the drilling surface, debris and drilling fluid
that may otherwise penetrate the interface and dislocate
impregnated segment 102 from support member 106.
58. Other variations of cutting element 100 may have non-circular
cross-sectional shapes, such as oval, elliptical, triangular,
rectangular, other polygonal shapes, or other shapes. Exemplary
variations of cutting element 100, which include impregnated
segments that protrude from the drill bit, are illustrated in FIGS.
13-15, wherein segments 107, 107', 107" are secured to drill bits
108, 108', 108" by support members 109, 109', 109",
respectively.
59. With reference to FIG. 16, another embodiment of a cutting
element 140 of the present invention is shown. Cutting element 140
includes a support member 142 that is securable to a socket 147
defined in the face of a drill bit 146. Thus, support member 142
extends from drill bit 146. Support member 142 includes a leading
face 144 which faces the direction of rotation of drill bit 146.
Cutting element 140 also includes an impregnated segment 148
secured thereto and disposed on leading face 144 so as to
facilitate contact of segment 148 with an interior surface of the
bore hole during rotation of drill bit 146. Support member 142 may
be supported from behind, relative to forces exerted thereagainst
during drilling, by a buttress 145 of bit body material.
60. FIG. 16a illustrates a variation of the cutting element 140',
wherein the support member 142' includes integral strengthening
webs or struts, which configuration facilitates the fabrication of
support member 142' with less material than that of support member
142 of the cutting element 140 of FIG. 16 and also provides
additional surface area to bond support member 142 to the bit
body.
61. FIG. 17 illustrates yet another embodiment of a cutting element
150, which includes a support member 152 that is securable to a
drill bit 156, such as in a socket 157 thereof, and includes a
recess 153, which is also referred to as a member-securing portion.
Recess 153 is configured to receive an impregnated segment 158, or
an extension thereof, and secure the impregnated segment 158
thereto. Support member 152 may alternatively be secured to a
matrix-type bit body during infiltration thereof.
62. FIG. 25 depicts an arcuate shaped cutting element 180 according
to the present invention. Cutting element 180 includes a support
member 182 that is securable to a drill bit, such as by a socket
thereof, and includes an impregnated segment 184 disposed
thereon.
63. The support member of the present invention facilitates an
increased exposure or profile of the impregnated segments relative
to that of conventional impregnated segments. This increased
exposure of the impregnated segments prevents the buildup of
formation fines on the cutting surface of the impregnated segments,
promotes self-sharpening of the impregnated segments, and reduces
the surface area of the footprint of the drill bit, which
facilitates the use of the drill bit hydraulics to clear formation
fines and debris from the surfaces of the borehole and the bit
face. Such use of the drill bit hydraulics to remove the formation
fines also reduces "pack off," which occurs as fines gather on the
impregnated segments, and which may reduce the depth of cut of the
drill bit. The increased exposure of the impregnated segments also
accommodates the cutting of hard "stringers," such as shale.
64. Referring to FIGS. 22-24, to enhance the strength with which an
impregnated segment is bound to its corresponding securing member,
the surface area of the interface 164, 164', 164" between an
impregnated segment 160, 160', 160" and its corresponding support
member 162, 162', 162", respectively, is preferably increased
relative to that if a flat interface is employed. Accordingly, the
segment-retaining portion of the support member 162, 162', 162" and
the member-securing portion of the impregnated segment 160, 160',
160", respectively, may each comprise rough, preferably
complementary, surfaces. Such high surface area interfaces prevent
shearing or delamination of an impregnated segment off of a support
member, which may be caused by bending stresses on the cutting
element or to normal forces on the cutting element parallel to the
member/segment interface. Accordingly, the mutually engaging
surfaces of the impregnated segment-support member interface 164,
164', and 164" may include complementary thread cut (see FIG. 22),
waffle (see FIG. 23), dove-tailed (see FIG. 24), dotted, or
cross-hatched surfaces; apertures or blind holes and complementary
protrusions; heavily sandblasted or otherwise roughened surfaces;
or other configurations that increase the mutually-engaging surface
areas of the two components. High surface area impregnated
segment-support member interfaces are particularly useful in
embodiments of the present invention that include relatively large,
thin impregnated segments.
65. With continued reference to FIG. 23, a support member 162'
according to the present invention may comprise a blade 163' of the
drill bit to which impregnated segment 160' is secured.
66. FIG. 18 depicts a drill bit 120 which includes a bit body 122,
a blank 126 that is partially disposed within the bit body, and a
threaded shank 131 extending from the blank, which attaches the
drill bit to a drill string, as known in the art. Bit body 122
carries a plurality of cutting elements 128 on the bit face 123
thereof. Cutting elements 128, which are preferably configured
similarly to cutting elements 60, 100 described above in reference
to FIGS. 4 and 5, and FIGS. 9 and 10, respectively, are preferably
disposed in sockets 130 formed in bit face 123. Sockets 130 are
preferably shaped complementarily to a bit attachment portion 70,
110 (see FIGS. 4 and 5, 9 and 10, respectively) of cutting elements
128.
67. Cutting elements 128 may be arranged in generally radial rows
that extend over the crown of bit body 122. Alternatively, as shown
in FIG. 19, cutting elements 128' may be disposed upon bit face
123' in rows 129' that extend somewhat spirally over the crown of
bit body 122'. As another alternative, FIG. 20 illustrates a drill
bit 120" that includes cutting elements 128" disposed over bit face
123" in a non-grouped arrangement. As yet another alternative, FIG.
21 illustrates a drill bit 120'" that includes cutting elements
128'" disposed over bit face 123'" in a concentric arrangement.
FIG. 26 illustrates a drill bit 186 that includes arcuate cutting
elements 180 (see FIG. 25) in a somewhat circumferential
arrangement thereon.
68. Preferably, adjacent cutting elements 128 are arranged on the
bit face such that, during drilling, the cutting elements cut the
formation surface at the end of the borehole evenly, and at a
substantially constant rate.
69. Referring again to FIG. 18, the support member 66, 106 (see
FIGS. 4 and 5, 9 and 10, respectively) of each cutting element 128
is secured within its corresponding socket 130 by known techniques,
such as by the use of adhesives, brazing, or mechanical affixation.
Alternatively, when support members 66, 106 are porous (e.g.,
comprised of sintered steel), they may be secured to bit body 122
during infiltration of a matrix material of bit body 122 as
described above in reference to FIG. 3.
70. Due to the use of support members 66, 106 in conjunction with
impregnated segments 62, 102, for the same reasons that were
discussed above in reference to FIG. 3, cutting elements 128 better
withstand the stresses of drilling and, therefore, may be
positioned upon drill bit 120 in a manner which improves the
hydraulic performance thereof relative to that of conventional
impregnated segment-bearing drill bits. Accordingly, an increased
amount of drilling fluid may be supplied to bit face 123, which
facilitates an increased rate of debris removal from the drilling
surface of the bore hole, a reduction in the amount of potentially
damaging friction that occurs during cutting, and an increase in
the rate at which cutting elements 128 are cooled.
71. Although the foregoing description contains many specifics,
these should not be construed as limiting the scope of the present
invention, but merely as providing illustrations of some of the
presently preferred embodiments. Similarly, other embodiments of
the invention may be devised which do not depart from the spirit or
scope of the present invention. The scope of this invention is,
therefore, indicated and limited only by the appended claims and
their legal equivalents, rather than by the foregoing description.
All additions, deletions and modifications to the invention as
disclosed herein which fall within the meaning and scope of the
claims are to be embraced thereby.
* * * * *