U.S. patent application number 16/167031 was filed with the patent office on 2019-02-21 for methods of forming earth-boring tools including replaceable cutting structures.
The applicant listed for this patent is Baker Hughes, a GE company, LLC. Invention is credited to Timothy K. Marvel, Suresh G. Patel, Chaitanya K. Vempati.
Application Number | 20190055790 16/167031 |
Document ID | / |
Family ID | 46063273 |
Filed Date | 2019-02-21 |
United States Patent
Application |
20190055790 |
Kind Code |
A1 |
Vempati; Chaitanya K. ; et
al. |
February 21, 2019 |
METHODS OF FORMING EARTH-BORING TOOLS INCLUDING REPLACEABLE CUTTING
STRUCTURES
Abstract
Methods of forming an earth-boring tool may involve attaching
one or more cutting elements to a replaceable cutting structure and
positioning the replaceable cutting structure proximate a region of
a body of an earth-boring tool that is susceptible to at least one
of localized wear and localized impact damage. The replaceable
cutting structure may be secured to the body. Methods of repairing
an earth-boring tool may involve bringing a replaceable cutting
structure proximate at least one portion of a body of an
earth-boring tool exhibiting at least one of localized wear and
localized impact damage. The replaceable cutting structure may be
attached to the earth-boring tool at the at least one portion.
Inventors: |
Vempati; Chaitanya K.;
(Conroe, TX) ; Marvel; Timothy K.; (The Woodlands,
TX) ; Patel; Suresh G.; (The Woodlands, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes, a GE company, LLC |
Houston |
TX |
US |
|
|
Family ID: |
46063273 |
Appl. No.: |
16/167031 |
Filed: |
October 22, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14824448 |
Aug 12, 2015 |
10107044 |
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16167031 |
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13299914 |
Nov 18, 2011 |
9115554 |
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14824448 |
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61415737 |
Nov 19, 2010 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 10/627 20130101;
B24D 3/06 20130101; B23K 31/025 20130101; E21B 12/02 20130101; Y10T
29/49744 20150115; Y10T 29/49746 20150115; Y10T 29/49741 20150115;
B23P 15/28 20130101; B28B 23/005 20130101; E21B 10/006 20130101;
E21B 10/633 20130101; Y10T 29/49742 20150115; Y10T 29/49734
20150115; E21B 10/62 20130101 |
International
Class: |
E21B 10/633 20060101
E21B010/633; B24D 3/06 20060101 B24D003/06; B23K 31/02 20060101
B23K031/02; B23P 15/28 20060101 B23P015/28; B28B 23/00 20060101
B28B023/00; E21B 10/00 20060101 E21B010/00; E21B 10/62 20060101
E21B010/62; E21B 12/02 20060101 E21B012/02; E21B 10/627 20060101
E21B010/627 |
Claims
1. A method of forming an earth-boring tool, comprising:
positioning an annular attachment member of a replaceable cutting
structure in a mold configured to form a body of an earth-boring
tool at a portion of the mold configured to form a region of the
body that is susceptible to localized wear, the replaceable cutting
structure comprising a cutting portion located to engage an earth
formation; and forming the body around the attachment member of the
replaceable cutting structure within the mold, the replaceable
cutting structure being located on each blade of a plurality of
blades at least within a shoulder region a face of the body,
wherein an exposed surface of the replaceable cutting structure is
at least substantially flush with exposed surfaces of the body
adjacent to the replaceable cutting structure, and wherein the
attachment member extends contiguously around a circumference of
the face of the body at least within the shoulder region.
2. The method of claim 1, wherein forming the body around the
replaceable cutting structure within the mold comprises one of
casting the body around the replaceable cutting structure within
the mold and sintering the body around the replaceable cutting
structure within the mold.
3. The method of claim 1, wherein forming the body around the
attachment member of the replaceable cutting structure within the
mold comprises forming an internal plenum extending at least
partially through the body and forming an outlet in fluid
communication with the internal plenum to extend from the internal
plenum to the replaceable cutting structure.
4. The method of claim 3, wherein the annular attachment member
comprises a channel extending at least partially through the
annular attachment member and wherein positioning the annular
attachment member in the mold comprises positioning the channel to
align with a location of formation of the outlet.
5. The method of claim 1, further comprising attaching a plurality
of cutting elements to the annular attachment member to form the
replaceable cutting structure before positioning the annular
attachment member within the mold.
6. The method of claim 5, wherein attaching the plurality of
cutting elements to the annular attachment member comprises
attaching a first cutting element of the plurality to the annular
attachment member at a first position relative to a central axis of
the annular attachment member and a second cutting element of the
plurality to the annular attachment member at a second position
relatively closer to the central axis of the annular attachment
member.
7. The method of claim 1, wherein forming the body around the
attachment member of the replaceable cutting structure within the
mold comprises casting the body around the attachment member of the
replaceable cutting structure within the mold.
8. The method of claim 1, wherein forming the body around the
attachment member of the replaceable cutting structure within the
mold comprises capturing the attachment member in the body due to
shrinkage of the body during a densification process.
9. The method of claim 1, wherein positioning the annular
attachment member of the replaceable cutting structure in the mold
comprising positioning the annular attachment member, the annular
attachment member comprising planar surfaces at right angles to one
another at inner and lower surfaces of the attachment member, in
the mold.
10. The method of claim 1, wherein forming the body around the
attachment member of the replaceable cutting structure within the
mold comprises forming at least one cutting element accommodation
recess in the body, the at least one cutting element accommodation
recess having a cutting element secured to the replaceable cutting
structure disposed at least partially therein.
11. The method of claim 1, wherein positioning the annular
attachment member of the replaceable cutting structure in the mold
comprises positioning the annular attachment member of the
replaceable cutting structure, a size of the replaceable cutting
structure corresponding to a predicted region of localized wear, in
the mold.
12. The method of claim 1, wherein positioning the annular
attachment member of the replaceable cutting structure in the mold
comprises positioning the annular attachment member, the annular
attachment member comprising a cermet material, in the mold.
13. The method of claim 1, further comprising disposing a
hardfacing material on an exterior portion of the annular
attachment member.
14. The method of claim 1, further comprising: retrieving the
earth-boring tool from a wellbore after using the earth-boring
tool, the earth-boring tool exhibiting at least one of localized
wear and localized impact damage and removing the replaceable
cutting structure; bringing another replaceable cutting structure
proximate each blade of a plurality of blades at least within a
shoulder region of a face of a body of the earth boring tool
exhibiting at least one of localized wear and localized impact
damage, the other replaceable cutting structure comprising an
annular attachment member exhibiting a geometry cooperative with
the body and each blade, and a cutting portion located to engage an
earth formation, wherein an exposed surface of the attachment
member is at least substantially flush with exposed surfaces of the
body adjacent to the attachment member, and wherein the attachment
member extends contiguously around a circumference of the face of
the body at least within the shoulder region; and attaching the
other replaceable cutting structure to each blade.
15. The method of claim 14, further comprising machining the at
least one portion of the body of the earth-boring tool to a
geometry predefined to cooperate with the geometry of the
attachment member.
16. The method of claim 14, further comprising positioning the
replaceable cutting structure over an outlet in fluid communication
with an internal plenum of the body.
17. The method of claim 16, wherein the annular attachment member
comprises a channel extending at least partially through the
annular attachment member and wherein positioning the replaceable
cutting structure over the outlet in fluid communication with the
internal plenum of the body comprises aligning the channel with the
outlet.
18. The method of claim 14, further comprising attaching a
plurality of cutting elements to the annular attachment member to
form the replaceable cutting structure.
19. The method of claim 18, wherein attaching the plurality of
cutting elements to the annular attachment member comprises
attaching a first cutting element of the plurality to the annular
attachment member at a first position relative to a central axis of
the annular attachment member and a second cutting element of the
plurality to the annular attachment member at a second position
relatively closer to the central axis of the annular attachment
member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 14/824,448, filed Aug. 12, 2015, which is scheduled to
issue as U.S. Pat. No. 10,107,044 on Oct. 23, 2018, which is a
divisional of U.S. patent application Ser. No. 13/299,914, filed
Nov. 18, 2011, now U.S. Pat. No. 9,115,554, issued Aug. 25, 2015,
which application claims the benefit of U.S. Provisional Patent
Application Ser. No. 61/415,737, filed Nov. 19, 2010, the
disclosure of each of which is hereby incorporated herein in its
entirety by this reference.
FIELD
[0002] Embodiments of the present disclosure relate generally to
earth-boring tools and, more specifically, to earth-boring tools
including replaceable cutting structures.
BACKGROUND
[0003] Earth-boring tools for forming wellbores in subterranean
earth formations may include a plurality of cutting elements
secured to a body. For example, fixed-cutter earth-boring rotary
drill bits (also referred to as "drag bits") include a plurality of
cutting elements that are fixedly attached to a bit body of the
drill bit, conventionally in pockets formed in blades and other
exterior portions of the bit body. Rolling cone earth-boring drill
bits include a plurality of cutters attached to bearing pins on
legs depending from a bit body. The cutters may include cutting
elements (sometimes called "teeth") milled or otherwise formed on
the cutters, which may include hardfacing on the outer surfaces of
the cutting elements, or the cutters may include cutting elements
(sometimes called "inserts") attached to the cutters,
conventionally in pockets formed in the cutters. Other bits might
include impregnated bits that typically comprise a body having a
face comprising a superabrasive impregnated material,
conventionally a natural or synthetic diamond grit or thermally
stable diamond elements dispersed in a matrix of surrounding body
material or segments of matrix material brazed to the bit body.
[0004] The cutting elements used in such earth-boring tools often
include polycrystalline diamond cutters (often referred to as
"PDCs"), which are cutting elements that include a polycrystalline
diamond (PCD) material. Such polycrystalline diamond cutting
elements are formed by sintering and bonding together relatively
small diamond grains or crystals under conditions of high
temperature and high pressure in the presence of a catalyst (such
as, for example, cobalt, iron, nickel, or alloys and mixtures
thereof) to form a layer of polycrystalline diamond material on a
cutting element substrate. These processes are often referred to as
high-temperature/high-pressure (or "HTHP") processes. The cutting
element substrate may comprise a cermet material (i.e., a
ceramic-metal composite material) such as, for example,
cobalt-cemented tungsten carbide. In such instances, the cobalt (or
other catalyst material) in the cutting element substrate may be
drawn into the diamond grains or crystals during sintering and
serve as a catalyst material for forming a diamond table from the
diamond grains or crystals. In other methods, powdered catalyst
material may be mixed with the diamond grains or crystals prior to
sintering the grains or crystals together in an HTHP process.
[0005] Exposed portions of cutting elements, such as, for example,
diamond tables, portions of substrates, hardfacing disposed on the
outer surfaces of cutting elements, and exposed surfaces of the
earth-boring tool, for example, blade surfaces and fluid courses
and junk slot surfaces of a drag bit or the cutters of a rolling
cone bit, may be subject to failure modes, such as, for example,
erosion, fracture, spalling, and diamond table delamination due to
abrasive wear, impact forces, and vibration during drilling
operations from contact with the formation being drilled. Some
portions of the earth-boring tool may be more susceptible to such
failure modes, and localized wear and localized impact damage may
cause the earth-boring tool to fail prematurely while leaving other
portions of the earth-boring tool in a usable condition. For
example, cutting elements and the blades to which they are attached
may be more susceptible to failure at the shoulder region of a face
of the bit body as compared to the central portion of the face of
the bit body or gage region of the bit body. In such instances, an
annular shaped groove may wear into the face of the bit body at the
shoulder region, a phenomenon sometimes referred to as "ring out"
or "pocket damage." Further, cutting elements and the blades to
which they are attached may be susceptible to failure at a central,
core region of a drill bit located on the face thereof, resulting
in "core out." Other earth-boring tools may similarly exhibit
localized wear in certain portions of the earth-boring tools.
BRIEF SUMMARY
[0006] In some embodiments, the present disclosure includes
earth-boring tools comprising a body and one or more replaceable
cutting structures attached to the body at a face region of the
body. Each replaceable cutting structure comprises an attachment
member and a cutting portion configured to engage an underlying
earth formation.
[0007] In additional embodiments, the present disclosure includes
an earth-boring tool, comprising a body and one or more replaceable
cutting structures. The body comprises a face comprising a shoulder
region adjacent a gage region and a plurality of blades extending
over the face through the shoulder region to, and including, the
gage region. Each replaceable cutting structure comprises an
attachment member, the attachment member comprising at least one
blade segment attached to a blade of the plurality of blades at the
shoulder region, and one or more cutting elements attached to the
at least one blade segment.
[0008] In further embodiments, the present disclosure includes
methods of forming an earth-boring tool comprising attaching one or
more cutting elements to a replaceable cutting structure;
positioning the replaceable cutting structure proximate a region of
a body of an earth-boring tool that is susceptible to at least one
of localized wear and localized impact damage; and attaching the
replaceable cutting structure to the body.
[0009] In additional embodiments, the present disclosure includes
methods of forming an earth-boring tool comprising attaching one or
more cutting elements to a replaceable cutting structure;
positioning the replaceable cutting structure proximate a region of
a body of an earth-boring tool that is susceptible to at least one
of localized wear and impact damage; and attaching the replaceable
cutting structure to the body at the region that is susceptible to
localized wear.
[0010] In still further embodiments, the present disclosure
includes methods of forming an earth-boring tool comprising
positioning a replaceable cutting structure in a mold configured to
form a body of an earth-boring tool at a portion of the mold
configured to form a region of the body that is susceptible to
localized wear; and forming the body around the replaceable cutting
structure within the mold.
[0011] In additional embodiments, the present disclosure includes
methods of repairing an earth-boring tool comprising bringing a
replaceable cutting structure proximate at least one portion of a
body of an earth-boring tool exhibiting at least one of localized
wear and localized impact damage, the replaceable cutting structure
comprising an attachment member exhibiting a geometry cooperative
with the at least one portion and a cutting portion configured to
engage an underlying earth formation; and attaching the replaceable
cutting structure to the earth-boring tool at the at least one
portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] While the specification concludes with claims particularly
pointing out and distinctly claiming that which is regarded as the
present disclosure, various features and advantages of embodiments
of this disclosure may be more readily ascertained from the
following description of embodiments of the disclosure when read in
conjunction with the accompanying drawings, in which:
[0013] FIG. 1 illustrates an overhead view of an earth-boring tool
including a replaceable cutting structure in accordance with an
embodiment of the present disclosure;
[0014] FIG. 2 illustrates a perspective view of the earth-boring
tool including the replaceable cutting structure shown in FIG.
1;
[0015] FIG. 3 illustrates a perspective view of a replaceable
cutting structure in accordance with an embodiment of the present
disclosure;
[0016] FIG. 4 illustrates a perspective view of an earth-boring
tool to which a replaceable cutting structure in accordance with
one or more embodiments of the disclosure may be attached;
[0017] FIG. 5 illustrates a perspective view of a plurality of
replaceable cutting structures in accordance with an embodiment of
the disclosure;
[0018] FIG. 6 illustrates a perspective view of an earth-boring
tool to which a plurality of replaceable cutting structures in
accordance with one or more embodiments of the disclosure may be
attached;
[0019] FIG. 7 illustrates a perspective view of an earth-boring
tool including a replaceable cutting structure in accordance with
an embodiment of the present disclosure;
[0020] FIG. 8 illustrates a perspective view of an earth-boring
tool including a replaceable cutting structure in accordance with
an embodiment of the present disclosure; and
[0021] FIG. 9 illustrates a partial perspective view of an
earth-boring tool including a replaceable cutting structure in
accordance with an embodiment of the present disclosure.
DETAILED DESCRIPTION
[0022] Some of the illustrations presented herein are not meant to
be actual views of any particular earth-boring tool, cutting
element, or replaceable cutting structure, but are merely idealized
representations that are employed to describe embodiments of the
present disclosure. Additionally, elements common between figures
may retain the same or similar numerical designation.
[0023] Although some embodiments of the present disclosure are
depicted as being used and employed in earth-boring rotary drill
bits, such as fixed-cutter rotary drill bits, persons of ordinary
skill in the art will understand that replaceable cutting
structures in accordance with the present disclosure may be
employed with any earth-boring tool. Accordingly, the terms
"earth-boring tool" and "earth-boring drill bit," as used herein,
mean and include any type of bit or tool used for drilling during
the formation or enlargement of a wellbore in a subterranean
formation and include, for example, rolling cone bits, core bits,
eccentric bits, bicenter bits, reamers, expandable reamers, mills,
drag bits, hybrid bits, impregnated bits, and other drilling bits
and tools known in the art.
[0024] As used herein, the term "cutting element" means and
includes any structure configured to engage an earth formation
including, by way of example and without limitation, tungsten
carbide inserts, polycrystalline diamond compact (PDC) cutting
elements and inserts, thermally stable polycrystalline (TSP)
diamond compact cutting elements, natural diamonds,
superabrasive-impregnated elements, and other cutting element
materials and structures as known in the art. In addition, cutting
elements and cutting faces thereof may include any geometric shape
or configuration, such as, for example, cylindrical, dome-shaped,
tombstone, chisel-shaped, pyramids, and other shapes and
configurations as known in the art.
[0025] Referring to FIGS. 1 and 2, an earth-boring tool 10
including a replaceable cutting structure 12 in accordance with the
present disclosure is shown. The earth-boring tool 10 includes a
body 13 comprising a face 14, a gage region 16, and a shoulder
region 18 at a radially outer portion of the face 14 proximate the
gage region 16. A plurality of circumferentially spaced blades 20
extends longitudinally from the face 14 over the shoulder region 18
and along the gage region 16. A plurality of junk slots 22 also
extends longitudinally from the face 14 over the shoulder region 18
and along the gage region 16 in the circumferential spaces between
adjacent blades 20. A plurality of cutting elements 24 is attached
to the body 13 on the blades 20 thereof. The cutting elements 24
may be at least partially disposed in recesses, which may also be
characterized as "pockets," formed in the blades 20.
[0026] A replaceable cutting structure 12 may be attached to the
earth-boring tool 10 at the shoulder region 18. In other
embodiments, a replaceable cutting structure may be attached to an
earth-boring tool at other locations such as, for example, on the
face of a rotary drag bit, on the face of an impregnated bit, on a
supporting ring of cutting elements of a roller cone on a rolling
cone drill bit. In further embodiments, a replaceable cutting
structure may be attached to an earth-boring tool on a
formation-engaging portion of a reamer tool, on a region of a
hybrid bit susceptible to at least one of localized wear and
localized impact damage, or on any other portion of an earth-boring
tool that is susceptible to at least one of localized wear and
localized impact damage as a result of drilling.
[0027] As shown in FIG. 3, a replaceable cutting structure 12 may
comprise an attachment member 26 in the form of a plurality of
blade segments 23 and a cutting portion configured to engage an
underlying earth formation. The cutting portion may comprise, for
example, a plurality of cutting elements 24, as shown in FIG. 3, or
a superabrasive material disposed in a matrix material, such as,
for example, a diamond material in a metal matrix. The blade
segments 23 may comprise interconnected portions of an annular
member generally conforming to an exterior shape of a body 13 of an
earth-boring tool 10 at a shoulder region 18 (see FIG. 4). Thus,
portions of blades 20 in the form of blade segments 23 and of
intervening junk slots 22 may be formed in the attachment member
26, enabling the attachment member 26 to provide an at least
substantially smooth transition between adjacent exterior surfaces
of the earth-boring tool 10 and the replaceable cutting structure
12. The replaceable cutting structure 12 may be configured to
attach to a body 13 of an earth-boring tool 10, for example, on the
face 14 thereof. The attachment member 26 may comprise planar
surfaces at right angles to one another at the inner and lower
surfaces of the attachment member 26, the planar surfaces being
configured to abut against and attach to cooperative surfaces on
the body 13 of an earth-boring tool 10. In other embodiments, the
inner and lower surfaces of attachment member 26, and the
cooperative surfaces of the body 13 may not be planes at right
angles to one another, but may be curved, angled, notched, or may
have other cooperative interface features, such as, for example,
recesses or protrusions, disposed thereon. In broad terms, the
attachment member 26 may be said to be configured for disposition
in one or more cooperatively configured seats on the body 13. The
cutting elements 24 are attached to the blade segments 23 of the
attachment member 26. The cutting elements 24 may be disposed in
multiple rows along the blade segments 23 of the attachment member
26. In other embodiments, the cutting elements 24 may be disposed
in a single row at the rotationally leading end of the blade
segments 23 or, alternatively, a single cutting element 24 may be
disposed on each blade segment 23 of the attachment member 26.
[0028] The attachment member 26 may comprise at least one cutting
element accommodation recess in an underside thereof. At least one
cutting element 24 already attached to an earth-boring tool 10 (see
FIG. 4) at a location of intended mounting of the attachment member
26 may protrude from a surface of the body 13 of the earth-boring
tool 10 in an area of seat 28 and, absent formation of at least one
corresponding cutting element accommodation recess, interfere with
attachment of the attachment member 26 to the body 13 of the
earth-boring tool 10. Each cutting element accommodation recess may
enable a corresponding cutting element 24 already mounted to the
body 13 to be partially disposed therein while enabling attachment
of the attachment member 26 to the body 13 of the earth-boring tool
10 with minimal cutting element 24 interference.
[0029] The size of the replaceable cutting structure 12 may
correspond to a predicted radially and circumferentially extending
region of localized wear occurring on a shoulder region 18 or other
region of a body 13 of an earth-boring tool 10 as a result of use
of the earth-boring tool 10 in a drilling or reaming operation. The
region of localized wear may be predicted using computer modeling,
such as, for example, finite element analysis, or by observation of
localized wear in the field. Thus, the replaceable cutting
structure 12 may be sized to enable easy replacement of a region of
a body 13 of an earth-boring tool 10 most susceptible to localized
wear and, therefore, most likely to cause premature failure of the
earth-boring tool 10. In addition, the replaceable cutting
structure 12 may enable replacement of a worn portion of an
earth-boring tool with a replaceable cutting structure 12 having
increased wear resistance, impact strength, fracture toughness, or
any combination of these.
[0030] Referring again to FIG. 4, an earth-boring tool 10 to which
a replaceable cutting structure 12 (see FIG. 3) may be attached is
shown. The earth-boring tool 10 includes a seat 28 formed in the
shoulder region 18 of the body 13 of the earth-boring tool 10.
Surfaces defining the seat 28 may be configured correspondingly to
abut against and attach to a replaceable cutting structure 12 (see
FIG. 3). Thus, the seat 28 may comprise planar surfaces at right
angles to one another. In other embodiments, the surfaces defining
the seat 28 and the adjacent surfaces of the replaceable cutting
structure 12 for mounting thereon may not be planes at right angles
to one another, but may be curved, angled, notched, or may have
interface features, such as, for example, recesses or protrusions,
disposed thereon. The material of the body 13 of the earth-boring
tool 10 may be machinable, enabling the surfaces that define the
seat 28 to be formed in the body 13. For example, if the body 13
suffers wear during a drilling operation, such wear may result in
uneven surfaces on the body 13, so the worn area may be machined to
relatively precise tolerances to form the seat 28 for placement and
attachment of the replaceable cutting structure 12 thereto.
[0031] The earth-boring tool 10, itself may comprise at least one
cutting element accommodation recess. At least one cutting element
24 attached to an attachment member 26 (see FIG. 3) may protrude
from a surface of the attachment member 26 of a replaceable cutting
structure 12 and, absent formation of at least one corresponding
cutting element accommodation recess in body 13, interfere with
attachment of the attachment member 26 to the body 13 of the
earth-boring tool 10. Each cutting element accommodation recess may
enable a corresponding cutting element 24 to be partially disposed
therein while enabling attachment of the attachment member 26 to
the body 13 of the earth-boring tool 10 with minimal cutting
element 24 interference.
[0032] As shown in FIG. 5, a plurality of replaceable cutting
structures 12 may be provided. Each replaceable cutting structure
12 may comprise one or more cutting elements 24 mounted to an
attachment member 26 in the form of a single blade segment 23
generally conforming to the shape of adjacent portions of blades 20
on a body 13 of an earth-boring tool 10 (see FIG. 6), enabling the
attachment member 26 to provide an at least substantially smooth
transition between the adjacent surfaces of the body 13 of the
earth-boring tool 10 and the replaceable cutting structure 12. Each
replaceable cutting structure 12 may be configured to attach to the
body 13 of the earth-boring tool 10. Each attachment member 26 may
comprise planar surfaces at right angles to one another at the
inner and lower surfaces of the attachment member 26, the planar
surfaces being configured to abut against and attach to the body 13
of an earth-boring tool 10. In other embodiments, the inner and
lower surfaces of the attachment member 26 may not be planes at
right angles to one another, but may be curved, angled, notched, or
may have interface features, such as, for example, recesses or
protrusions, disposed thereon. The cutting elements 24 may be
disposed in multiple rows along the blade segments 23 formed in the
attachment member 26. In other embodiments, the cutting elements 24
may be disposed in a single row at the rotationally leading end of
the blade segments 23 or a single cutting element 24 may be
disposed on each blade segment 23 of the attachment member 26.
[0033] The attachment member 26 may comprise at least one cutting
element accommodation recess. At least one cutting element 24
attached to a body 13 of an earth-boring tool 10 (see FIG. 4) may
protrude from a surface of the body 13 of the earth-boring tool 10
in the area of seat 28 and, absent formation of at least one
corresponding cutting element accommodation recess, interfere with
attachment of the attachment member 26 to the body 13 of the
earth-boring tool 10. Each cutting element accommodation recess may
enable a corresponding cutting element 24 on body 13 to be
partially disposed in the underside of attachment member 26 while
enabling attachment of the attachment member 26 to the body 13 of
the earth-boring tool 10 with minimal cutting element 24
interference.
[0034] As previously noted, size of the replaceable cutting
structure 12 may correspond to a predicted region of localized wear
on a shoulder region 18 or other region of an earth-boring tool 10.
The region of localized wear may be predicted using computer
modeling, such as, for example, finite element analysis, or by
observation of localized wear in the field. Thus, the replaceable
cutting structure 12 may be sized to enable easy replacement of a
region of an earth-boring tool 10 most susceptible to localized
wear and, therefore, most likely to cause premature failure of the
earth-boring tool 10.
[0035] Referring to FIG. 6, an earth-boring tool 10 to which a
plurality of replaceable cutting structures 12 (see FIG. 5) may be
attached is shown. The earth-boring tool 10 includes a plurality of
seats 28 formed in blades 20 at the shoulder region 18 of a body 13
of the earth-boring tool 10. Surfaces defining the seats 28 may be
configured correspondingly to abut against and attach to a like
plurality of replaceable cutting structures 12 in the form of blade
segments 23 (see FIG. 5). Thus, the seats 28 may comprise planar
surfaces at right angles to one another. In other embodiments, the
surfaces defining the seats 28 and cooperative surfaces of blade
segments 23 may not be planes at right angles to one another, but
may be curved, angled, notched, or may have interface features,
such as, for example, recesses or protrusions, disposed thereon.
The material of the body 13 of the earth-boring tool 10 may be
machinable, enabling the surfaces that define the seat 28 to be
formed in the body 13.
[0036] The earth-boring tool 10 may comprise at least one cutting
element accommodation recess. At least one cutting element 24
attached to an attachment member 26 of a replaceable cutting
structure 12 (see FIG. 3) may protrude from a surface of the
attachment member 26 and, absent formation of at least one
corresponding cutting element accommodation recess, interfere with
attachment of the attachment member 26 to the body 13 of the
earth-boring tool 10. Each cutting element accommodation recess may
enable a corresponding cutting element 24 to be partially disposed
therein while enabling attachment of the attachment member 26 to
the body 13 of the earth-boring tool 10 with minimal cutting
element 24 interference.
[0037] Attachment members 26 of replaceable cutting structures 12,
such as blade segments 23, may comprise strong, tough, and impact-
and abrasion-resistant materials suitable for use in earth-boring
applications. For example, an attachment member 26 may comprise a
metal or metal alloy, such as, for example, steel, or may comprise
a cermet material, such as, for example, sintered tungsten carbide
in a matrix material. A hardfacing material may, optionally, be
disposed on an exterior portion of the attachment member 26.
[0038] Attachment members 26 may be formed by casting a metal part
and subsequently machining desired features, such as, for example,
attachment surfaces or pockets for receiving cutting elements 24,
into the metal part. Alternatively, attachment members 26 may be
formed by distributing a plurality of hard particles, such as, for
example, tungsten carbide particles, and a plurality of particles
comprising a matrix material, such as, for example, copper,
copper-based alloys, cobalt, and cobalt-based alloys, in a mold
(not shown). In some cases, the matrix material may be melted and
infiltrated into the plurality of hard particles. In other cases,
the hard particles and particles comprising a matrix material may
then be pressed in the mold to form a green part. The hard
particles and particles comprising a matrix material may then be
subjected to a densification process. For example, the green part
may be subjected to heat and pressure to at least partially sinter
the green part. The green part may be partially sintered to form a
brown part, or may be sintered to a final density. The green,
brown, or fully sintered part may also have desired features, such
as, for example, attachment surfaces or cutting element 24 pockets,
formed therein. Such desired features may be machined, for example,
in a green or brown part, or may be molded into an infiltrated part
or a fully sintered part. Cutting elements 24 may be attached to
the attachment member 26 in pockets formed therein by welding,
brazing, shrink-fit, by being captured due to shrinkage of the
attachment member 26 during a densification process, or by other
means as known in the art. Cutting elements 24 may be attached to
the attachment member 26 before or after the attachment member 26
is, itself attached to a body 13 of an earth-boring tool 10.
[0039] Replaceable cutting structures 12 may be attached to bodies
13 of earth-boring tools 10. For example, at least one replaceable
cutting structure 12 may be attached to a body 13 of an
earth-boring tool 10 by welding, by brazing, by shrink-fit, by
press-fit, by screws, by bolts, by pins, by keys, by mutually
engaging threads on a replaceable cutting structure 12 and a body
13, by being captured due to shrinkage of an earth-boring tool 10
during a densification process, or by other means as known in the
art. Alternatively, at least one preformed replaceable cutting
structure 12 may be placed in a mold. The body 13 of an
earth-boring tool 10 may then be cast in the mold around the
replaceable cutting structure 12, thereby attaching it to the body
13 of the earth-boring tool 10.
[0040] In operation, a replaceable cutting structure 12 may be
subjected to greater wear than other regions of an earth-boring
tool 10 during a drilling or reaming operation, resulting in
localized wear of the replaceable cutting structure 12. For
example, as a rotary drag bit rotates in a borehole and engages the
underlying earth formation, the combination of abrasive wear,
impact forces, and vibrations may cause the replaceable cutting
structure 12 to wear down more quickly than other portions and
features of the earth-boring tool 10, such as, for example, other
portions of the face 14, and the gage region 16. When an operator
determines that the replaceable cutting structure 12 has worn down
to a selected extent, or when the bit ceases to drill an underlying
earth formation at an acceptable rate in the borehole, the
earth-boring tool 10 may be extracted from the borehole. The body
13 of the bit and remaining portions of the replaceable cutting
structure 12 may be machined to return a seat 28 at a shoulder
region 18 of the body 13 to a geometry it exhibited prior to being
deployed in the borehole or to a new, selected geometry. Another
replaceable cutting structure 12 may then be attached to the body
13, and the earth-boring tool 10 redeployed in the borehole or
deployed in another borehole. Therefore, replaceable cutting
structures 12 may increase the useful life of an earth-boring tool
10 by enabling replacement of the region most susceptible to
localized wear and, therefore, most likely to cause premature
failure of the earth-boring tool 10.
[0041] An earth-boring tool 10 may comprise one or more failure
detection features. Referring to FIG. 7, an earth-boring tool 10
comprising a plurality of outlets 30 exposed at an outer surface of
a replaceable cutting structure 12 is shown. The outlets 30
comprise channels formed in the replaceable cutting structure 12
and having openings at the outer surface of the replaceable cutting
structure 12 at a rotationally leading end thereof. A plurality of
channels 32 is formed internally in a body 13 of the earth-boring
tool 10 corresponding to and aligned with the outlets 30, placing
the outlets 30 in fluid communication with an internal plenum 34
formed in the body 13 of the earth-boring tool 10. As the
earth-boring tool 10 engages the underlying earth formation,
drilling fluid is pumped down the internal plenum 34, through the
channels 32, and out the outlets 30, which may have
flow-controlling and directing nozzles (not shown) adjacent the
face 14. The outlets 30 may enable cooling at a region of the
earth-boring tool 10 and replaceable cutting structure 12 most
susceptible to wear and heat generation. The outlets 30 may also
enable drilling fluid to be directed at cutting elements 24,
removing cuttings and carrying them up through junk slots 22 (see
FIGS. 1 and 2). When the replaceable cutting structure 12 becomes
worn to a point where replacement is desirable or necessary,
cuttings from the earth formation may become lodged in the channels
32 or worn outlets 30, causing a pressure spike in drilling fluid
pressure which is detectable at the rig floor (not shown).
Therefore, the nozzles 30 may enable an operator to detect when the
replaceable cutting structure 12 should or must be replaced.
[0042] As shown in FIG. 8, outlets 30 may also be located at an
interface 36 between a body 13 of an earth-boring tool 10 and a
replaceable cutting structure 12. The outlets 30 comprise openings
formed in the body 13 and are located at the interface 36 between
the replaceable cutting structure 12 and the body 13. A plurality
of channels 32 is formed internally in the body 13 of the
earth-boring tool 10 leading to the outlets 30, placing the outlets
30 in fluid communication with an internal plenum 34 formed in the
body 13 of the earth-boring tool 10. As the earth-boring tool 10
engages the underlying earth formation, drilling fluid is pumped
down the internal plenum 34, through the channels 32, and to the
outlets 30. When the replaceable cutting structure 12 becomes worn
to a point where the outlets 30 become exposed, the drilling fluid
may begin circulating through the nozzles, causing a pressure drop
in drilling fluid pressure, which is detectable at the rig floor.
Therefore, the outlets 30 may enable an operator to detect when the
replaceable cutting structure 12 should or must be replaced.
[0043] Referring to FIG. 9, a self-sharpening replaceable cutting
structure 12 attached to a body 13 of an earth-boring tool 10 is
shown. The self-sharpening replaceable cutting structure 12
includes a first plurality of cutting elements 24. The first
plurality of cutting elements 24 is attached to an attachment
member 26 of the replaceable cutting structure 12, and at least a
portion of each cutting element 24 of the first plurality is
exposed. Cutting elements 24 of the first plurality are configured
to engage an earth formation directly once the earth-boring tool 10
is deployed. The self-sharpening replaceable cutting structure 12
further comprises at least another plurality of cutting elements
24. Cutting elements 24 of the at least another plurality are
located below cutting elements 24 of the first plurality. In other
words, the cutting elements 24 of the at least another plurality
are located closer to an axial centerline 38 of the body 13 than
the cutting elements 24 of the first plurality. The cutting
elements 24 of the at least another plurality may be completely
embedded within the attachment member 26. For example, the
attachment member 26 may be formed around the cutting elements 24
of the at least another plurality. In other embodiments, cutting
elements 24 of the at least another plurality may be at least
partially exposed, being disposed in pockets formed in the
attachment member 26. As the earth-boring tool 10 engages an
underlying earth formation, the first plurality of cutting elements
24 and the attachment member 26 may wear down to a point where the
cutting elements 24 of the first plurality become so worn as to be
dislodged. The at least another plurality of cutting elements 24
may then be exposed and begin engaging the earth formation. Thus,
the at least another plurality of cutting elements 24 may enable
the replaceable cutting structure 12 to be self-sharpening.
[0044] While the present disclosure has been described herein with
respect to certain embodiments, those of ordinary skill in the art
will recognize and appreciate that it is not so limited. Rather,
many additions, deletions, and modifications to the embodiments
described herein may be made without departing from the scope of
the disclosure as hereinafter claimed, including legal equivalents.
In addition, features from one embodiment may be combined with
features of another embodiment while still being encompassed within
the scope of the disclosure as contemplated by the inventors.
* * * * *