U.S. patent application number 15/691256 was filed with the patent office on 2019-02-28 for cutting element assemblies comprising rotatable cutting elements, downhole tools comprising such cutting element assemblies, and related methods.
The applicant listed for this patent is Baker Hughes, a GE company, LLC. Invention is credited to Alexander Rodney Boehm, John Abhishek Raj Bomidi, Kegan L. Lovelace, William A. Moss, Jr., Jon David Schroder.
Application Number | 20190063162 15/691256 |
Document ID | / |
Family ID | 65434152 |
Filed Date | 2019-02-28 |
United States Patent
Application |
20190063162 |
Kind Code |
A1 |
Bomidi; John Abhishek Raj ;
et al. |
February 28, 2019 |
CUTTING ELEMENT ASSEMBLIES COMPRISING ROTATABLE CUTTING ELEMENTS,
DOWNHOLE TOOLS COMPRISING SUCH CUTTING ELEMENT ASSEMBLIES, AND
RELATED METHODS
Abstract
Rotatable cutting element assemblies includes a sleeve, a
centering element positioned at least partially within the sleeve,
a biasing element configured to apply a force against the centering
element, and a rotatable cutting element coupled to the centering
element and configured to rotate relative to the sleeve.
Earth-boring tools include a tool body and at least one rotatable
cutting element assembly coupled to the tool body. The at least one
rotatable cutting element assembly includes a sleeve fixedly
coupled to the tool body, a centering element positioned at least
partially within the sleeve, a rotatable cutting element coupled to
the centering element, and a biasing element configured to apply a
force against the centering element. Methods of forming an
earth-boring tool include positioning a centering element within a
sleeve, fixedly coupling the sleeve to a tool body, and coupling a
rotatable cutting element to the centering element.
Inventors: |
Bomidi; John Abhishek Raj;
(Spring, TX) ; Moss, Jr.; William A.; (Conroe,
TX) ; Schroder; Jon David; (The Woodlands, TX)
; Boehm; Alexander Rodney; (Wheat Ridge, CO) ;
Lovelace; Kegan L.; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes, a GE company, LLC |
Houston |
TX |
US |
|
|
Family ID: |
65434152 |
Appl. No.: |
15/691256 |
Filed: |
August 30, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 10/43 20130101;
E21B 10/55 20130101 |
International
Class: |
E21B 10/55 20060101
E21B010/55; E21B 10/43 20060101 E21B010/43 |
Claims
1. A rotatable cutting element assembly for an earth-boring tool,
comprising: a sleeve comprising a sidewall and a protrusion
extending inward from the sidewall; a centering element positioned
at least partially within the sleeve and configured to abut against
the protrusion; a biasing element configured to apply a force
against the centering element toward the protrusion; and a
rotatable cutting element coupled to the centering element and
configured to rotate relative to the sleeve.
2. The rotatable cutting element assembly of claim 1, wherein: the
centering element comprises a bore extending at least partially
through the centering element; and the rotatable cutting element
comprises a hole extending at least partially through the rotatable
cutting element along a central axis of the rotatable cutting
element.
3. The rotatable cutting element assembly of claim 2, further
comprising a fastener coupling the rotatable cutting element to the
centering element using the bore and the hole.
4. The rotatable cutting element assembly of claim 2, wherein the
bore extends fully through the centering element and the hole
extends fully through the rotatable cutting element.
5. The rotatable cutting element assembly of claim 2, wherein the
hole in the rotatable cutting element is a stepped through-hole
comprising a first portion that is wider than a second portion, a
lip defined at a transition from the first portion to the second
portion.
6. The rotatable cutting element assembly of claim 1, wherein: a
portion of the centering element protrudes from the sleeve past the
protrusion of the sleeve; and the rotatable cutting element
comprises a centering surface complementary to an exterior surface
of the protruding portion of the centering element.
7. The rotatable cutting element assembly of claim 1, wherein,
absent external forces, a gap is defined between a bottom surface
of the rotatable cutting element and a top surface of the
sleeve.
8. The rotatable cutting element assembly of claim 1, wherein the
rotatable cutting element is configured to rotate about its central
axis relative to the sleeve.
9. The rotatable cutting element assembly of claim 1, wherein the
sleeve comprises a base, further comprising a fastener threaded to
the base and extending through at least a portion of the rotatable
cutting element and the centering element.
10. The rotatable cutting element assembly of claim 1, further
comprising a centering element support positioned between the
centering element and the biasing element.
11. An earth-boring tool, comprising: a tool body; and at least one
rotatable cutting element assembly coupled to the tool body, the at
least one rotatable cutting element assembly comprising: a sleeve
fixedly coupled to the tool body; a centering element positioned at
least partially within the sleeve; a rotatable cutting element
coupled to the centering element and configured to rotate relative
to the tool body; and a biasing element configured to apply a force
against the centering element.
12. The earth-boring tool of claim 11, wherein the sleeve comprises
a sidewall and a protrusion extending inward from the sidewall, the
protrusion sized and shaped to maintain the centering element at
least partially within the sleeve.
13. The earth-boring tool of claim 11, wherein the sleeve is brazed
to the tool body.
14. The earth-boring tool of claim 11, wherein the tool body
comprises a fixed blade, and the sleeve is positioned within a
pocket in the fixed blade.
15. The earth-boring tool of claim 11, further comprising a
fastener coupling the rotatable cutting element to the centering
element.
16. The earth-boring tool of claim 15, wherein the fastener extends
into a hole formed in the tool body.
17. A method of forming an earth-boring tool, the method
comprising: positioning a centering element within a sleeve;
positioning a biasing element within the sleeve and adjacent to the
centering element; fixedly coupling the sleeve to a tool body
within a pocket of the tool body; and coupling a rotatable cutting
element to the centering element, the rotatable cutting element
rotatable relative to the tool body.
18. The method of claim 17, further comprising attaching a base of
the sleeve to a sidewall of the sleeve after positioning the
centering element and the biasing element within the sleeve to
maintain the centering element and the biasing element within the
sleeve.
19. The method of claim 17, wherein coupling the rotatable cutting
element to the centering element comprises attaching the rotatable
cutting element to a ball with a fastener.
20. The method of claim 19, wherein the rotatable cutting element
is rotatable about its central axis relative to the fastener and
relative to the tool body.
Description
FIELD
[0001] Embodiments of this disclosure relate generally to rotatable
cutting elements for downhole earth-boring tools, earth-boring
tools including such cutting elements, and related methods.
BACKGROUND
[0002] Wellbores are formed in subterranean formations for various
purposes including, for example, extraction of oil and gas from the
subterranean formation and extraction of geothermal heat from the
subterranean formation. Wellbores may be formed in a subterranean
formation using an earth-boring tool, such as an earth-boring
rotary drill bit or a reamer. Different types of earth-boring
rotary drill bits are known in the art, including fixed-cutter bits
(which are often referred to in the art as "drag" bits),
rolling-cutter bits (which are often referred to in the art as
"rock" bits), diamond-impregnated bits, and hybrid bits (which may
include, for example, both fixed cutters and rolling cutters).
Reamers are used to enlarge a wellbore, and may also include one or
more cutters. The drill bit or reamer is rotated and advanced into
the subterranean formation. Upon rotation, the cutters or abrasive
structures thereof cut, crush, shear, and/or abrade away the
formation material to form or enlarge the wellbore. A diameter of
the wellbore drilled by the drill bit may be defined by the cutting
structures disposed at the largest outer diameter of the drill bit
or reamer.
[0003] The drill bit or reamer is coupled, either directly or
indirectly, to what is referred to in the art as a "drill string,"
which comprises a series of elongated tubular segments connected
end-to-end that extends into the wellbore from the surface of earth
above the subterranean formations being drilled. Various tools and
components, including the drill bit or reamer, may be coupled
together, such as proximate or at the distal end of the drill
string at the bottom of the wellbore being drilled. An assembly of
tools and components at the end of the drill string is referred to
in the art as a "bottom hole assembly" (BHA).
[0004] The drill bit or reamer may be rotated within the wellbore
by rotating the drill string from the surface of the formation, or
the drill bit or reamer may be rotated with a downhole motor, which
is also coupled to the drill string and disposed proximate the
bottom of the wellbore. The downhole motor may include, for
example, a hydraulic Moineau-type motor having a shaft, to which
the drill bit is mounted, that may be caused to rotate by pumping
fluid (e.g., drilling mud or fluid) from the surface of the
formation down through the center of the drill string, through the
hydraulic motor, out from nozzles in the drill bit, and back up to
the surface of the formation through the annular space between the
outer surface of the drill string and the exposed surface of the
formation within the wellbore. The downhole motor may be operated
with or without drill string rotation.
[0005] The drill string may include a number of components in
addition to a downhole motor and drill bit and/or reamer including,
without limitation, drill pipe, drill collars, stabilizers,
measuring while drilling (MWD) equipment, logging while drilling
(LWD) equipment, downhole communication modules, and other
components.
[0006] In addition to drill strings, other tool strings may be
disposed in an existing well bore for, among other operations,
completing, testing, stimulating, producing, and remediating
hydrocarbon-bearing formations.
[0007] Cutting elements used in earth boring tools often include
polycrystalline diamond compact (often referred to as "PDC")
cutting elements, which are cutting elements that include so-called
"tables" of a polycrystalline diamond material mounted to
supporting substrates and presenting a cutting face for engaging a
subterranean formation. Polycrystalline diamond (often referred to
as "PCD") material is material that includes inter-bonded grains or
crystals of diamond material. In other words, PCD material includes
direct, intergranular bonds between the grains or crystals of
diamond material.
[0008] Cutting elements are typically mounted on a drill bit or
reamer body by brazing. The body is formed with recesses therein,
commonly termed "pockets," for receiving a substantial portion of
each cutting element in a manner to present the PCD layer at an
appropriate back rake and side rake angle, facing in the direction
of intended drill bit or reamer rotation, for cutting in accordance
with the drill bit or reamer design. In such cases, a brazing
compound is applied between the surface of the substrate of the
cutting element and the surface of the recess on the body in which
the cutting element is received. The cutting elements are installed
in their respective recesses in the body, and heat is applied to
each cutting element via a torch to raise the temperature to a
point high enough to braze the cutting elements to the bit body in
a fixed position, but not so high as to damage the PCD layer.
[0009] Unfortunately, securing a PDC cutting element to a drill bit
or reamer restricts the useful life of such cutting element,
because the cutting edge of the diamond table and the substrate
wear down, creating a so-called "wear flat" and necessitating
increased weight-on-bit to maintain a given rate of penetration of
the drill bit or reamer into the formation due to the increased
surface area presented. In addition, unless the cutting element is
heated for removal and then rebrazed with an unworn portion of the
cutting edge presented for engaging a formation, more than half of
the cutting element is never used.
[0010] Rotatable cutting elements mounted for rotation about a
longitudinal axis of the cutting element can wear more evenly than
fixed cutting elements, and exhibit a significantly longer useful
life without removal from the earth-boring tool. That is, as a
cutting element rotates in a body of an earth-boring tool,
different parts of the cutting edges or surfaces may be exposed at
different times, such that more of the cutting element is used.
Thus, rotatable cutting elements may have a longer life than fixed
cutting elements.
BRIEF SUMMARY
[0011] In some embodiments, rotatable cutting element assemblies
include a sleeve including a sidewall and a protrusion extending
inward from the sidewall, a centering element positioned at least
partially within the sleeve and configured to abut against the
protrusion, a biasing element configured to apply a force against
the centering element toward the protrusion, and a rotatable
cutting element coupled to the centering element and configured to
rotate relative to the sleeve.
[0012] In some embodiments, earth-boring tools include a tool body
and at least one rotatable cutting element assembly coupled to the
tool body. The at least one rotatable cutting element assembly
includes a sleeve fixedly coupled to the tool body, a centering
element positioned at least partially within the sleeve, a
rotatable cutting element coupled to the centering element and
configured to rotate relative to the tool body, and a biasing
element configured to apply a force against the centering
element.
[0013] In certain embodiments, methods of forming an earth-boring
tool include positioning a centering element within a sleeve,
positioning a biasing element within the sleeve and adjacent to the
centering element, fixedly coupling the sleeve to a tool body
within a pocket of the tool body, and coupling a rotatable cutting
element to the centering element, the rotatable cutting element
rotatable relative to the tool body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a simplified schematic diagram of a drilling
system using cutting element assemblies disclosed herein.
[0015] FIG. 2 is a simplified perspective view of a fixed-blade
earth-boring rotary drill bit that may be used in conjunction with
the drilling system of FIG. 1.
[0016] FIG. 3 is a simplified cross section showing a cutting
element assembly according to an embodiment of this disclosure,
mounted in a blade of an earth-boring tool, such as in a blade of
the fixed-blade earth-boring rotary drill bit of FIG. 2.
[0017] FIGS. 4 and 5 are simplified cross-sectional views showing
additional embodiments of rotatable cutting elements for use in
cutting element assemblies.
[0018] FIGS. 6 and 7 are simplified cross-sectional views showing
additional embodiments of centering elements for use in cutting
element assemblies.
[0019] FIG. 8 is a simplified cross section showing a cutting
element assembly according to another embodiment of this
disclosure, mounted in a blade of an earth-boring tool, such as in
a blade of the fixed-blade earth-boring rotary drill bit of FIG.
2.
DETAILED DESCRIPTION
[0020] The illustrations presented herein are not actual views of
any particular cutting assembly, tool, or drill string, but are
merely idealized representations employed to describe example
embodiments of the present disclosure. The following description
provides specific details of embodiments of the present disclosure
in order to provide a thorough description thereof. However, a
person of ordinary skill in the art will understand that the
embodiments of the disclosure may be practiced without employing
many such specific details. Indeed, the embodiments of the
disclosure may be practiced in conjunction with conventional
techniques employed in the industry. Only those process acts and
structures necessary to understand the embodiments of the
disclosure are described in detail below. Additional conventional
acts and structures may be used. Also note, any drawings
accompanying the application are for illustrative purposes only,
and are thus not drawn to scale. Additionally, elements common
between figures may have corresponding numerical designations.
[0021] As used herein, the terms "comprising," "including,"
"containing," "characterized by," and grammatical equivalents
thereof are inclusive or open-ended terms that do not exclude
additional, un-recited elements or method steps, but also include
the more restrictive terms "consisting of," "consisting essentially
of," and grammatical equivalents thereof.
[0022] As used herein, the term "may" with respect to a material,
structure, feature, or method act indicates that such is
contemplated for use in implementation of an embodiment of the
disclosure, and such term is used in preference to the more
restrictive term "is" so as to avoid any implication that other
compatible materials, structures, features, and methods usable in
combination therewith should or must be excluded.
[0023] As used herein, the term "configured" refers to a size,
shape, material composition, and arrangement of one or more of at
least one structure and at least one apparatus facilitating
operation of one or more of the structure and the apparatus in a
predetermined way.
[0024] As used herein, the singular forms following "a," "an," and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise.
[0025] As used herein, the term "and/or" includes any and all
combinations of one or more of the associated listed items.
[0026] As used herein, spatially relative terms, such as "upward,"
"downward," "lower," "bottom," "above," "upper," "top," and the
like, may be used for ease of description to describe one element's
or feature's relationship to another element(s) or feature(s) as
illustrated in the figures. Unless otherwise specified, the
spatially relative terms are intended to encompass different
orientations of the materials in addition to the orientation
depicted in the figures.
[0027] As used herein, the term "substantially" in reference to a
given parameter, property, or condition means and includes to a
degree that one of ordinary skill in the art would understand that
the given parameter, property, or condition is met with a degree of
variance, such as within acceptable manufacturing tolerances. By
way of example, depending on the particular parameter, property, or
condition that is substantially met, the parameter, property, or
condition may be at least 90.0% met, at least 95.0% met, at least
99.0% met, or even at least 99.9% met.
[0028] As used herein, the term "about" used in reference to a
given parameter is inclusive of the stated value and has the
meaning dictated by the context (e.g., it includes the degree of
error associated with measurement of the given parameter).
[0029] As used herein, the term "hard material" means and includes
any material having a Knoop hardness value of about 1,000
kg.sub.f/mm.sup.2 (9,807 MPa) or more. Hard materials include, for
example, diamond, cubic boron nitride, boron carbide, tungsten
carbide, etc.
[0030] As used herein, the term "intergranular bond" means and
includes any direct atomic bond (e.g., covalent, metallic, etc.)
between atoms in adjacent grains of material.
[0031] As used herein, the term "polycrystalline hard material"
means and includes any material comprising a plurality of grains or
crystals of the material that are bonded directly together by
intergranular bonds. The crystal structures of the individual
grains of polycrystalline hard material may be randomly oriented in
space within the polycrystalline hard material.
[0032] As used herein, the term "earth-boring tool" means and
includes any type of tool used for drilling during the formation or
enlargement of a wellbore and includes, for example, rotary drill
bits, percussion bits, core bits, eccentric bits, bi-center bits,
reamers, mills, drag bits, roller-cone bits, hybrid bits, and other
drilling bits and tools known in the art.
[0033] FIG. 1 is a schematic diagram of an example of a drilling
system 100 using cutting element assemblies disclosed herein. FIG.
1 shows a wellbore 110 that may include an upper section 111 with a
casing 112 installed therein and a lower section 114 that is being
drilled with a drill string 118. The drill string 118 may include a
tubular member 116 that carries a drilling assembly 130 at its
bottom end. The tubular member 116 may be coiled tubing or may be
formed by joining drill pipe sections. A drill bit 150 (also
referred to as the "pilot bit") may be attached to the bottom end
of the drilling assembly 130 for drilling a first, smaller diameter
borehole 142 in a formation 119. A reamer 160 may be placed above
or uphole of the drill bit 150 in the drill string 118 to enlarge
the first, smaller diameter borehole 142 to a second, larger
diameter borehole 120. The terms wellbore and borehole are used
herein as synonyms.
[0034] The drill string 118 may extend to a rig 180 at the surface
167. The rig 180 shown is a land rig for ease of explanation. The
apparatus and methods disclosed herein equally apply when an
offshore rig is used for drilling underwater. A drive system 169
(e.g., a rotary table or a top drive) may rotate the drill string
118 and the drilling assembly 130, and thus the pilot bit 150 and
reamer 160, to respectively form boreholes 142 and 120. The rig 180
may also include conventional devices, such as mechanisms to add
additional sections to the tubular member 116 as the wellbore 110
is drilled. A surface control unit 190, which may be a
computer-based unit, may be placed at the surface for receiving and
processing downhole data transmitted by the drilling assembly 130
and for controlling the operations of various devices and sensors
170 in the drilling assembly 130. A drilling fluid from a source
179 thereof may be pumped under pressure through the tubular member
116, discharged through the pilot bit 150, and returned to the
surface via the annular space (also referred to as the "annulus")
between the drill string 118 and an inside wall of the wellbore
110.
[0035] During operation, when the drill string 118 is rotated, both
the pilot bit 150 and the reamer 160 may rotate. The pilot bit 150
may drill the first, smaller diameter borehole 142, while
simultaneously the reamer bit 160 may enlarge the first, smaller
diameter borehole borehole 142 to a second, larger diameter
borehole 120. The earth's subsurface formation 119 may contain rock
strata made up of different rock structures that can vary from soft
formations to very hard formations, and therefore the pilot bit 150
and/or the reamer 160 may be selected based on the formations
expected to be encountered in a drilling operation.
[0036] FIG. 2 is a perspective view of a fixed-cutter earth-boring
rotary drill bit 200 that may be used in conjunction with the
drilling system 100 of FIG. 1. For example, the drill bit 200 may
be the pilot bit 150 shown in FIG. 1. The drill bit 200 includes a
bit body 202 that may be secured to a shank 204 having a threaded
connection portion 206 (e.g., an American Petroleum Institute (API)
threaded connection portion) for attaching the drill bit 200 to a
drill string (e.g., drill string 118, shown in FIG. 1). In some
embodiments, the bit body 202 may be secured to the shank 204 using
an extension 208. In other embodiments, the bit body 202 may be
secured directly to the shank 204.
[0037] The bit body 202 may include internal fluid passageways that
extend between the face 203 of the bit body 202 and a longitudinal
bore, extending through the shank 204, the extension 208, and
partially through the bit body 202. Nozzle inserts 214 also may be
provided at the face 203 of the bit body 202 within the internal
fluid passageways. The bit body 202 may further include a plurality
of blades 216 that are separated by junk slots 218. In some
embodiments, the bit body 202 may include gage wear plugs 222 and
wear knots 228. A plurality of cutting element assemblies 210 may
be mounted on the face 203 of the bit body 202 in cutting element
pockets 212 that are located along each of the blades 216. The
cutting element assemblies 210 may include PDC cutting elements, or
may include other cutting elements. For example, some or all of the
cutting element assemblies 210 may be or include a cutting element
assembly 300 including rotatable cutting elements, as described
below and shown in FIGS. 3-7.
[0038] FIG. 3 is a simplified cross-sectional view showing a
cutting element assembly 300 mounted in a blade 302 of an
earth-boring tool. The blade 302 may be, for example, one of the
blades 216 shown in FIG. 2. The cutting element assembly 300 may be
one of the cutting element assemblies 210 shown in FIG. 2. In some
embodiments, the blade 302 may be a body of a roller cone, a body
of a reamer, or a body of any earth-boring tool or component that
may employ a cutting element. Accordingly, the earth-boring tools
of this disclosure are not limited to fixed-cutter rotary drill
bits.
[0039] The cutting element assembly 300 may include a sleeve 304
secured to the blade 302. For example, the sleeve 304 may be
brazed, welded, and/or threaded within a pocket 303 of the blade
302. In other embodiments, the sleeve 304 may be integrally formed
with the blade 302, such that there is no physical interface
between the sleeve 304 and the blade 302.
[0040] The sleeve 304 may have a generally cylindrical interior
surface 306 defined by a sidewall 308. An inward protrusion 310 may
extend from a top portion of the sidewall 308, the inward
protrusion defining an inner surface coextensive with the generally
cylindrical inner surface 306 of the sidewall 308. The sleeve 304
may also include a base 312, which may be integral with or coupled
to a bottom portion of the sidewall 308 at an interface 314. By way
of example, the base 312 may be welded, brazed, threaded, or
press-fit to the sidewall 308 at the interface 314. A central hole
316 may extend at least partially (e.g., fully) through the base
312. An inner surface 318 of the central hole 316 may be threaded.
In some embodiments, a hole 320 (shown in broken lines in FIG. 3)
may be present in the blade 302 in a position to be aligned with
the central hole 316 of the base 312 of the sleeve 304. The hole
320 in the blade 302 may be threaded.
[0041] A centering element 322 may be positioned partially within
the sleeve 308 and retained therein by the inward protrusion 310 of
the sleeve 304. As used herein, the term "centering element" means
and includes structures including an angled upper surface,
including structures having a substantially spherical,
hemispherical, tapered, or ellipsoid shape, for example. The inner
surface of the inward protrusion 310 may have a shape corresponding
to an exterior surface the centering element 322, such as an
arcuate inner surface corresponding to a ball-shaped centering
element 322, for example. A bore 324 may generally centrally extend
through the centering element 322. A top portion of the centering
element 322 may protrude out of the sleeve 304 past the inward
protrusion 310. The generally cylindrical interior surface 306 of
the sidewall 308 may have a diameter that is at least as large as
the largest diameter of the centering element 322, while the inward
protrusion 310 may have a smallest inner diameter that is smaller
than the largest diameter of the centering element 322. Thus, the
inward protrusion 310 may retain a majority portion of the
centering element 322 within the sleeve 304.
[0042] A biasing element 326 (e.g., a coil spring) may also be
positioned within the sleeve 304 between the centering element 322
and the base 312 of the sleeve. The biasing element 326 may force
the centering element 322 upward against the inward protrusion 310,
but allow some movement of the centering element 322 downward upon
application of a sufficient downward force on the centering element
322. Optionally, in some embodiments, a centering element support
328 may be positioned between the centering element 322 and the
biasing element 326. If present, the centering element support 328
may include an upper surface corresponding to an exterior surface
of the centering element 322.
[0043] A rotatable cutting element 330 may be positioned over and
rotatably coupled to the sleeve 304 and centering element 322. The
rotatable cutting element 330 may include a substrate 332 and a
cutting table 334. The substrate 332 may include, for example,
cobalt-cemented tungsten carbide or another carbide material. The
cutting table 334 may include a hard material, such as a
polycrystalline hard material, bonded to the substrate 332. In
other embodiments, the rotatable cutting element 330 may be formed
entirely of the polycrystalline hard material, or may include
another material in addition to the polycrystalline hard material
and the substrate 332. The cutting table 334 may include diamond
(synthetic or natural), cubic boron nitride, or another hard
material.
[0044] The cutting table 334 may be generally cylindrical, and may
also include chamfers or other surface shapes and features as known
to one of ordinary skill in the art. Alternatively, the cutting
table 334 may also be shaped to be non-cylindrical. In some
embodiments, as shown in FIG. 3, the rotatable cutting element 330
may include a generally central through-hole 336 extending through
the cutting table 334 and substrate 332. The through-hole 336 may
include a wide portion 338 and a narrow portion 340, defining a lip
342 at a transition between the wide portion 338 and the narrow
portion 340. Centrally located on the substrate 332 on a side
thereof opposite the cutting table 334 may be a centering surface
344. The centering surface 344 may be configured for bearing
against the centering element 322. Thus, the centering surface 344
may have a shape and size (e.g., radius of curvature) complementary
to an exterior surface of the centering element 322.
[0045] A bottom surface 346 of the rotatable cutting element 330
may extend radially outward from the centering surface 344. A top
surface 348 of the sleeve 304 may extend radially outward from the
inward protrusion 310. The bottom surface 346 of the rotatable
cutting element 330 and the top surface 348 of the sleeve 304 may
be positioned to oppose each other. Initially and absent sufficient
external forces on the rotatable cutting element 330 to overcome a
force imposed on the rotatable cutting element 330 by the biasing
element 326 through the centering element 322, the bottom surface
346 of the rotatable cutting element 330 may be at least partially
separated from the top surface 348 of the sleeve 304 by a gap.
However, the gap may be removed by a downward force (e.g., an
operating force between the rotatable cutting element 330 and a
formation) sufficient to overcome the upward force from the biasing
element 326. Thus, during use and operation, the bottom surface 346
of the rotatable cutting element 330 and the top surface 348 of the
sleeve 304 may be bearing surfaces for rotation of the rotatable
cutting element 330.
[0046] A fastener 350 (e.g., a fastener, a pin, a screw, etc.) may
be positioned to extend at least partially through the through-hole
336 of the rotatable cutting element 330, the bore 324 of the
centering element 322, the central hole 316 of the base 312 of the
sleeve 308, and, if present, the hole 320 in the blade 302. The
fastener 350 may be configured and positioned to couple the
rotatable cutting element 330 to the sleeve 308 and centering
element 322, while allowing the rotatable cutting element 330 to
rotate about its central axis, relative to the sleeve 308 and blade
302. The fastener 350 may be secured to the base 312 of the sleeve
304, such as via threads in the central hole 316 of the base 312,
and/or to the blade 302, such as via threads in the hole 320 of the
blade 302. In some embodiments, the hole 320 of the blade 302 may
be provided without threads as a clearance recess to receive an end
of the fastener 350 as the fastener 350 extends through the central
hole 316 of the base 312.
[0047] Absent external forces, the rotatable cutting element 330
may be forced upward by the biasing element 326 through the
centering element 322, such that the head of the fastener 350 may
abut against the lip 342 of the rotatable cutting element 330.
During operation, if a sufficient downward force acts on the
rotatable cutting element 330, the lip 342 may become spaced from
the head of the fastener 350. The shaft of the fastener 350 have a
diameter that is smaller than the narrow portion 340 of the
through-hole 336, to allow for rotation of the rotatable cutting
element 330 about the fastener 350. The centering element 322 may
be configured to rotate together with the rotatable cutting element
330, or the rotatable cutting element 330 may rotate independently
of the centering element 322. To facilitate rotation of the
rotatable cutting element 330, a lubricant (e.g., oil, drilling
fluid) may be provided between the rotatable cutting element 330
and the pocket 303 of the blade 302, between the bottom surface 346
of the substrate 332 of the rotatable cutting element 330 and the
top surface 348 of the sleeve 304, between the fastener 350 and the
narrow portion 340 of the through-hole 336, and/or between the
centering surface 344 of the substrate 332 of the rotatable cutting
element 330 and the centering element 322. After assembly and
during operation, the centering surface 344 of the rotatable
cutting element 330 may substantially continuously abut against the
centering element 322, due to force applied by the biasing element
326.
[0048] In case the rotatable cutting element 330 becomes worn or
broken, it may be replaced by simply removing the fastener 350 and
coupling a new rotatable cutting element 330 to the cutting element
assembly 300 by replacing the fastener 350 (or a new fastener 350).
The replacement of the rotatable cutting element 330 may be
accomplished without removing the sleeve 304 from the blade 302.
For example, the weld or braze between the sleeve 304 and the blade
302 may remain intact while the rotatable cutting element 330 is
replaced.
[0049] Accordingly, embodiments of this disclosure may enable
simple, cost-effective replacement of the rotatable cutting element
330, while maintaining the integrity of brazes and/or welds that
couple the cutting element assembly 300 to the blade 302. In
addition, the centering element 322 may facilitate centering of the
rotatable cutting element 330 relative to the sleeve 304, and may
provide a bearing surface on which the rotatable cutting element
330 may rotate. Moreover, the biasing element 326 may be selected
to provide an upward force on the rotatable cutting element 330
that is tailored to facilitate rotation of the rotatable cutting
element 330 at a particular threshold downward force on the
rotatable cutting element 330. For example, a relatively stronger
biasing element 326 may be selected to reduce or eliminate rotation
of the rotatable cutting element 330 at a relatively low force, due
to increased force and friction between the lip 342 and the head of
the fastener 350. Likewise, a relatively weaker biasing element 326
may be selected to facilitate rotation of the rotatable cutting
element 330 even at relatively low forces, due to decreased force
and friction between the lip 342 and the head of the fastener
350.
[0050] In some embodiments, an earth-boring tool including
rotatable cutting elements may be formed by positioning the
centering element 322 within the sleeve 304 and against the inward
protrusion 310. The bore 324 through the centering element 322 may
be generally aligned with a central axis of the sleeve 304.
Optionally, the centering element support 328 may also be
positioned within the sleeve 304 and against the centering element
322. The biasing element 326 may be placed against the centering
element 322 (or against the centering element support 328, if
present) and at least partially within the sleeve 304. The base 312
may be coupled (e.g., threaded, brazed, and/or welded) to the
sidewall 308 of the sleeve 304, which may force the biasing element
326 to compress and to force the centering element 322 against the
inward protrusion 310. The sleeve 304, assembled with the centering
element 322, biasing element 326, and base 312, may be coupled to
the blade 302 of an earth-boring tool, such as by brazing, welding,
and/or threading the sleeve 304 within the pocket 303 of the blade
302. The rotatable cutting element 330 may be positioned over the
sleeve 304 and centering element 322, and rotatably coupled thereto
by passing the fastener 350 through the rotatable cutting element
330, through the centering element 322, and at least partially into
the central hole 316 of the base 312 of the sleeve 304. The
fastener 350 may be secured to the sleeve 304 using the central
hole 316 and/or to the blade 302 using the hole 320 in the blade
302, as discussed above. The rotatable cutting element 330 may
later be replaced by removing the fastener 350, removing the
rotatable cutting element 330, positioning a new rotatable cutting
element 330 in its place, and replacing the fastener 350 (or
positioning a new fastener 350) as described above.
[0051] Additional embodiments of rotatable cutting elements and
centering elements are illustrated in FIGS. 4 through 7. Referring
to FIG. 4, a rotatable cutting element 400 according to another
embodiment, for use in a cutting element assembly similar to that
described with reference to FIG. 3, may include a substrate 402, a
cutting table 404, a straight through-hole 406, and a centering
surface 408. The rotatable cutting element 400 may be similar to
the rotatable cutting element 330 described above with reference to
FIG. 3, except the straight through-hole 406 may have a
substantially uniform cross-sectional diameter. Accordingly, the
straight through-hole 406 may lack a narrow portion, a wide
portion, and a lip between a narrow portion and a wide portion. The
rotatable cutting element 400 with the straight through-hole 406
may be rotatably coupled to remaining portions of a cutting element
assembly by passing a fastener through the straight through-hole
406, with a head of the fastener resting on the cutting table
404.
[0052] Referring to FIG. 5, a rotatable cutting element 500
according to another embodiment, for use in a cutting element
assembly similar to that described with reference to FIG. 3, may
include a substrate 502, a cutting table 504, and a blind hole 506
extending into the substrate 502 from a centering surface 508. The
rotatable cutting element 500 with the blind hole 506 may be
rotatably coupled to remaining portions of a cutting element
assembly by passing a fastener upward through at least a centering
element, and optionally through a base of a sleeve (as described
above in relation to FIG. 3) and into the blind hole 506. The
fastener may be secured to the substrate 502 at the blind hole 506
via threads, a braze, and/or a weld. The fastener and rotatable
cutting element 500 may be configured to rotate relative to the
centering element and/or sleeve.
[0053] Referring to FIG. 6, a centering element 600 according to
another embodiment, for use in a cutting element assembly similar
to that described with reference to FIG. 3, may include a stepped
bore 602 including a wide portion 604 and a narrow portion 606,
with a lip 608 at a transition from the wide portion 604 to the
narrow portion 606. The centering element 600 may be employed in
embodiments in which a fastener may be positioned with its head in
the wide portion 604 of the stepped bore 602 and its shaft
extending through the narrow portion 606 to be coupled to a
rotatable cutting element. In embodiments employing the centering
element 600, the centering element 600 and a corresponding
rotatable cutting element (e.g., rotatable cutting element 330,
400, or 500) may rotate relative to a sleeve and/or blade together,
or the centering element 600 and corresponding rotatable cutting
element may be rotatable relative to each other.
[0054] Referring to FIG. 7, a centering element 700 according to
another embodiment, for use in a cutting element assembly similar
to that described with reference to FIG. 3, may include a blind
bore 702. The centering element 700 may be employed in embodiments
in which a fastener may be positioned with its shaft extending at
least partially through a corresponding rotatable cutting element
(e.g., rotatable cutting element 330, 400, or 500) to be coupled to
the centering element 700, such as via threads, a weld, or a braze
within the blind bore 702. The centering element 700 may rotate
together with the corresponding rotatable cutting element relative
to a sleeve and/or blade, or the corresponding rotatable cutting
element may rotate about the fastener independent from the
centering element 700.
[0055] Referring to FIG. 8, a cutting element assembly 800
according to another embodiment may include a sleeve 804 configured
for coupling to a blade 802 within a pocket 803 of the blade 802, a
centering element 822 positioned at least partially within the
sleeve 804, a biasing element 826 within the sleeve 804, a
rotatable cutting element 830 coupled to the centering element 822
by a fastener 850, and, optionally, a centering element support 828
between the biasing element 826 and the centering element 822. The
cutting element assembly 800 shown in FIG. 8 may be similar to the
cutting element assembly 300 shown in FIG. 3, but the shape and
configuration of the centering element 822 and corresponding
structures of the sleeve 804, rotatable cutting element 830, and
optional centering element support 828 may be different than those
shown in FIG. 3.
[0056] For example, referring to FIG. 8, the centering element 822
may have a generally cylindrical lateral outer surface, with a
tapered upper surface 852. The rotatable cutting element 830 may
include a tapered centering surface 844 that is complementary to
the tapered upper surface 852 of the centering element 822. An
inward protrusion 810 of the sleeve 804 may have a complementary
shape and size to a retention surface 854 along the generally
cylindrical lateral outer surface of the centering element 822,
such that the biasing element 826 may force the centering element
822 upward until the retention surface 854 abuts against the inward
protrusion 810, absent counteracting external forces sufficient to
overcome the force from the biasing element 826. Although the
retention surface 854 is shown in FIG. 8 as extending radially
outward normal to the generally cylindrical lateral outer surface
of the centering element 822, in other embodiments the retention
surface 854 may be angled upward or downward (from the perspective
shown in FIG. 8). If the optional centering element support 828 is
included, its upper surface may be complementary in shape to a
lower surface of the centering element 822. Accordingly, it is
contemplated that centering elements according to this disclosure
may have various shapes and configurations.
[0057] Additional non-limiting example embodiments of the
disclosure are described below.
Embodiment 1
[0058] A rotatable cutting element assembly for an earth-boring
tool, comprising a sleeve comprising a sidewall and a protrusion
extending inward from the sidewall; a centering element positioned
at least partially within the sleeve and configured to abut against
the protrusion; a biasing element configured to apply a force
against the centering element toward the protrusion; and a
rotatable cutting element coupled to the centering element and
configured to rotate relative to the sleeve.
Embodiment 2
[0059] The rotatable cutting element assembly of Embodiment 1,
wherein: the centering element comprises a bore extending at least
partially through the centering element; and the rotatable cutting
element comprises a hole extending at least partially through the
rotatable cutting element along a central axis of the rotatable
cutting element.
Embodiment 3
[0060] The rotatable cutting element assembly of Embodiment 2,
further comprising a fastener coupling the rotatable cutting
element to the centering element using the bore and the hole.
Embodiment 4
[0061] The rotatable cutting element assembly of Embodiment 2 or
Embodiment 3, wherein the bore extends fully through the centering
element and the hole extends fully through the rotatable cutting
element.
Embodiment 5
[0062] The rotatable cutting element assembly of any of Embodiments
2 through 4, wherein the hole in the rotatable cutting element is a
stepped through-hole comprising a first portion that is wider than
a second portion, a lip defined at a transition from the first
portion to the second portion.
Embodiment 6
[0063] The rotatable cutting element assembly of any of Embodiments
1 through 5, wherein: a portion of the centering element protrudes
from the sleeve past the protrusion of the sleeve; and the
rotatable cutting element comprises a centering surface
complementary to an exterior surface of the protruding portion of
the centering element.
Embodiment 7
[0064] The rotatable cutting element assembly of any of Embodiments
1 through 6, wherein, absent external forces, a gap is defined
between a bottom surface of the rotatable cutting element and a top
surface of the sleeve.
Embodiment 8
[0065] The rotatable cutting element assembly of any of Embodiments
1 through 7, wherein the rotatable cutting element is configured to
rotate about its central axis relative to the sleeve.
Embodiment 9
[0066] The rotatable cutting element assembly of any of Embodiments
1 through 8, wherein the sleeve comprises a base, further
comprising a fastener threaded to the base and extending through at
least a portion of the rotatable cutting element and the centering
element.
Embodiment 10
[0067] The rotatable cutting element assembly of any of embodiments
1 through 9, further comprising a centering element support
positioned between the centering element and the biasing
element.
Embodiment 11
[0068] An earth-boring tool, comprising: a tool body; and at least
one rotatable cutting element assembly coupled to the tool body,
the at least one rotatable cutting element assembly comprising: a
sleeve fixedly coupled to the tool body; a centering element
positioned at least partially within the sleeve; a rotatable
cutting element coupled to the centering element and configured to
rotate relative to the tool body; and a biasing element configured
to apply a force against the centering element.
Embodiment 12
[0069] The earth-boring tool of Embodiment 11, wherein the sleeve
comprises a sidewall and a protrusion extending inward from the
sidewall, the protrusion sized and shaped to maintain the centering
element at least partially within the sleeve.
Embodiment 13
[0070] The earth-boring tool of Embodiment 11 or Embodiment 12,
wherein the sleeve is brazed to the tool body.
Embodiment 14
[0071] The earth-boring tool of any of Embodiments 11 through 13,
wherein the tool body comprises a fixed blade, and the sleeve is
positioned within a pocket in the fixed blade.
Embodiment 15
[0072] The earth-boring tool of any of Embodiments 11 through 14,
further comprising a fastener coupling the rotatable cutting
element to the centering element.
Embodiment 16
[0073] The earth-boring tool of Embodiment 15, wherein the fastener
extends into a hole formed in the tool body.
Embodiment 17
[0074] A method of forming an earth-boring tool, the method
comprising: positioning a centering element within a sleeve;
positioning a biasing element within the sleeve and adjacent to the
centering element; fixedly coupling the sleeve to a tool body
within a pocket of the tool body; and coupling a rotatable cutting
element to the centering element, the rotatable cutting element
rotatable relative to the tool body.
Embodiment 18
[0075] The method of Embodiment 17, further comprising attaching a
base of the sleeve to a sidewall of the sleeve after positioning
the centering element and the biasing element within the sleeve to
maintain the centering element and the biasing element within the
sleeve.
Embodiment 19
[0076] The method of Embodiment 17 or Embodiment 18, wherein
coupling the rotatable cutting element to the centering element
comprises attaching the rotatable cutting element to a ball with a
fastener.
Embodiment 20
[0077] The method of Embodiment 19, wherein the rotatable cutting
element is rotatable about its central axis relative to the
fastener and relative to the tool body.
[0078] While the present invention has been described herein with
respect to certain illustrated 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
illustrated embodiments may be made without departing from the
scope of the invention as claimed, including legal equivalents
thereof. In addition, features from one embodiment may be combined
with features of another embodiment while still being encompassed
within the scope of the invention as contemplated by the inventors.
Further, embodiments of the disclosure have utility with different
and various tool types and configurations.
* * * * *