U.S. patent application number 16/046704 was filed with the patent office on 2019-01-31 for earth-boring tools including cutting element profiles configured to reduce work rates.
The applicant listed for this patent is Baker Hughes, a GE company, LLC. Invention is credited to Alexander Rodney Boehm, Travis Nissley.
Application Number | 20190032411 16/046704 |
Document ID | / |
Family ID | 65037716 |
Filed Date | 2019-01-31 |
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United States Patent
Application |
20190032411 |
Kind Code |
A1 |
Nissley; Travis ; et
al. |
January 31, 2019 |
EARTH-BORING TOOLS INCLUDING CUTTING ELEMENT PROFILES CONFIGURED TO
REDUCE WORK RATES
Abstract
Earth-boring tools may include a body including blades
projecting therefrom, an axis of rotation, and cutting elements
secured to the blades. A profile of the cutting elements
intersecting outermost points of cutting faces of the cutting
elements as viewed projected rotationally onto a plane may be
parabolic from immediately proximate the axis of rotation to a nose
point at which a slope of the profile is such that an angle between
the profile and a plane perpendicular to the axis of rotation is
about 0.degree.. In other embodiments, a first section of the
profile may extend at a first slope, and a second section of the
profile may extend at a second, different slope. In still other
embodiments, a tangent line to the profile may be oriented at an
angle of at least 15.degree. at a location proximate to the axis of
rotation.
Inventors: |
Nissley; Travis; (Herndon,
VA) ; Boehm; Alexander Rodney; (Wheat Ridge,
CO) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baker Hughes, a GE company, LLC |
Houston |
TX |
US |
|
|
Family ID: |
65037716 |
Appl. No.: |
16/046704 |
Filed: |
July 26, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62538320 |
Jul 28, 2017 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 10/43 20130101 |
International
Class: |
E21B 10/43 20060101
E21B010/43 |
Claims
1. An earth-boring tool comprising: a body comprising blades
projecting therefrom, the blades extending generally radially
outwardly from an axis of rotation of the tool; and cutting
elements secured to the blades; wherein a profile of the cutting
elements secured to the blades intersecting outermost points of
cutting faces of the cutting elements as viewed projected
rotationally onto a plane, within which an axis of rotation of the
body is located, is parabolic from immediately proximate the axis
of rotation to a nose point at which a slope of the profile is such
that an angle between the profile and a plane perpendicular to the
axis of rotation is about 0.degree..
2. The earth-boring tool of claim 1, wherein a slope of the profile
proximate to the axis of rotation of the body is such that an angle
between the profile and a plane perpendicular to the axis of
rotation is at least about 15.degree..
3. The earth-boring tool of claim 1, wherein a slope of the profile
proximate to the axis of rotation of the body is such that an angle
between the profile and a plane perpendicular to the axis of
rotation is about 35.degree. or less.
4. The earth-boring tool of claim 1, wherein the nose point is
located at least one-half of a radius of the body from the axis of
rotation.
5. The earth-boring tool of claim 1, wherein the nose point is
located at less than three-fourths of a radius of the body from the
axis of rotation.
6. The earth-boring tool of claim 1, wherein surfaces of the blades
as projected onto the plane perpendicular to the direction of
rotation of the blades comprise a plurality of line segments, each
line segment extending tangent to a parabolic curve extending from
proximate to the axis of rotation to proximate to the nose
point.
7. The earth-boring tool of claim 6, wherein a number of the line
segments is at least five.
8. An earth-boring tool comprising: a body comprising blades
extending outward from a remainder of the body; and cutting
elements secured to the blades; wherein a first section of a
profile of a face formed by a least squares fit to outermost points
of cutting faces of the cutting elements secured to the blades as
viewed projected rotationally onto a plane, within which plane an
axis of rotation of the body is located, may be linear and may
extend at a first slope relative to a plane perpendicular to the
axis of rotation of the body from proximate to the axis of rotation
of the body radially outward; wherein a second section of the
profile of the face surrounding and extending radially outward from
the first section may be linear and may extend at a second,
different slope relative to the plane perpendicular to the axis of
rotation of the body; and wherein a third section of the profile
may be located radially outward from the second section, the third
section arcing from the second slope away from a leading end of the
body.
9. The earth-boring tool of claim 8, wherein the first slope is two
to four times as great as the second slope relative to the plane
perpendicular to the axis of rotation of the body.
10. The earth-boring tool of claim 8, wherein the first slope is
such that an angle between the first section and a plane
perpendicular to the axis of rotation is between about 10.degree.
and about 35.degree. relative to the plane perpendicular to an axis
of rotation of the body.
11. The earth-boring tool of claim 8, wherein the second slope is
such that an angle between the second section and a plane
perpendicular to the axis of rotation is between about 10.degree.
and about 20.degree. relative to the plane perpendicular to the
axis of rotation of the body.
12. The earth-boring tool of claim 8, wherein a transition between
the first slope and the second slope occurs a radial distance at
least about one-half of a radial distance occupied by the first and
second slopes.
13. The earth-boring tool of claim 8, wherein a transition between
the first slope and the second slope occurs a radial distance less
than about three-fourths of a radial distance occupied by the first
and second slopes.
14. An earth-boring tool comprising: a body comprising blades
extending outward from a remainder of the body; and cutting
elements secured to the blades; wherein a profile formed by a least
squares fit to outermost points of cutting faces of the cutting
elements secured is oriented at an angle of at least 15.degree.
relative to a plane perpendicular to an axis of rotation of the
body at a location proximate to an axis of rotation of the
body.
15. The earth-boring tool of claim 14, the profile is oriented at
an angle of about 30.degree. or less relative to the plane
perpendicular to the axis of rotation at the location proximate to
the axis of rotation.
16. The earth-boring tool of claim 14, wherein the profile is
parabolic from immediately proximate the axis of rotation to a nose
point at which a slope of the profile is such that an angle between
a line tangent to the profile and a plane perpendicular to the axis
of rotation is about 0.degree..
17. The earth-boring tool of claim 16, wherein the nose point is
located at least one-half of a radius of the body from the axis of
rotation.
18. The earth-boring tool of claim 16, wherein the nose point is
located at less than three-fourths of a radius of the body from the
axis of rotation.
19. The earth-boring tool of claim 14, wherein surfaces of the
blades as projected onto a plane perpendicular to a direction of
rotation of the blades comprise a plurality of line segments, each
line segment extending tangent to a parabolic curve extending from
proximate to the axis of rotation to proximate to the nose
point.
20. The earth-boring tool of claim 19, wherein a number of the line
segments is at least five.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit under 35 U.S.C. .sctn.
119(e) of U.S. Provisional Patent Application Ser. No. 62/538,320,
filed Jul. 28, 2017, the disclosure of which is hereby incorporated
herein in its entirety by this reference.
TECHNICAL FIELD
[0002] This disclosure relates generally to earth-boring tools and
methods of making and using earth-boring tools. More specifically,
disclosed embodiments relate generally to profile configurations
for faces of earth-boring tools that may reduce work rate for
cutting elements, reduce bit imbalance, reduce loads borne by
cutting elements on at least some selected areas of the bit face,
and improve or maintain cutting removal efficiency.
BACKGROUND
[0003] 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 a drill bit, such as an earth-boring rotary drill
bit. 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). A fixed-cutter drill bit comprises a bit body
attached to a shank which will have a threaded portion to connect
to the rest of the bottom hole assembly. The bit body will have a
crown which contacts the formation to be drilled. In the crown are
nozzle inserts for connecting to internal fluid passageways to
provide drilling fluid or mud to the face of the bit body. The
crown also has junk slots to allow for removal of cuttings from the
formation and mud back up to the surface. The crown also has
blades, onto which are attached cutting elements which engage and
remove the formation material during a drilling operation. The
profile of the crown, which may be characterized as the face of the
bit is, in a majority of modern drag bits employing polycrystalline
diamond compact (PDC) cutters, divided up into regions by their
relationship to a longitudinal axis or centerline of the bit. The
area near the center of the drill bit, the rotational axis, is
referred to as the cone region. From the cone region, moving
radially outwardly, other regions of the crown are; the nose, the
shoulder, and the gage region. The profile of the crown is such
that typically the nose region is the first to contact the
formation as the drill bit advances into the formation during
drilling.
[0004] During drilling, the drill bit is rotated and advanced into
the subterranean formation. As the drill bit rotates, the cutters
on the face of the bit and extending to the gage, cut and shear the
formation material to form the wellbore. A diameter of the wellbore
drilled by the drill bit may be defined by the cutting structures
disposed at the gage, the largest outer diameter of the drill
bit.
[0005] The drill bit is coupled, either directly or indirectly, to
an end of 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, may be coupled together at the
distal end of the drill string at the bottom of the wellbore being
drilled. This assembly of tools and components is referred to in
the art as a "bottom hole assembly" (BHA).
[0006] The drill bit may be rotated within the wellbore by rotating
the drill string from the surface of the formation, or the drill
bit may be rotated by coupling the drill bit to 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 borehole. The downhole motor may be operated
with or without drill string rotation.
[0007] Because the drill string can be of considerable length, the
drilling assembly and the drill bit can exhibit a variety of
motions in addition to the rotation of the drill bit along a linear
path. Such motions are generally referred to as dysfunctions and
include vibration, displacement of the tool along a direction other
than the drilling direction, bending moments and whirl. Whirl
occurs in rotating members such as drill strings, drill bits,
shafts, etc. Often whirl induces failures in the bottom hole
assembly components and damages the drill bit.
[0008] The time required to drill a well is greatly affected by the
number of times the drill bit must be changed in order to reach the
targeted formation. This is the case because each time the bit is
changed, the entire string of drill pipe, which may be miles
(kilometers) long, must be retrieved from the borehole, section by
section. Once the drill string has been retrieved and the new bit
installed, the bit must be lowered to the bottom of the borehole on
the drill string, which again must be constructed section by
section. This process requires considerable time, effort and
expense. The length of time that a drill bit may be employed before
it must be changed depends upon its rate of penetration ("ROP"), as
well as its durability.
BRIEF SUMMARY
[0009] In some embodiments, earth-boring tools may include a body
including blades projecting therefrom, the blades extending
generally radially outwardly from an axis of rotation of the tool.
Cutting elements may be secured to the blades. A profile of the
cutting elements secured to the blades intersecting outermost
points of cutting faces of the cutting elements as viewed projected
rotationally onto a plane, within which an axis of rotation of the
body may be located, may be parabolic from immediately proximate
the axis of rotation to a nose point at which a slope of the
profile is such that an angle between the profile and a plane
perpendicular to the axis of rotation is about 0.degree..
[0010] In other embodiments, earth-boring tools may include a body
having blades extending outward from a remainder of the body.
Cutting elements may be secured to the blades. A first section of a
profile of a face formed by a least squares fit to outermost points
of cutting faces of the cutting elements secured to the blades as
viewed projected rotationally onto a plane, within which plane an
axis of rotation of the body is located, may be linear and may
extend at a first slope relative to a plane perpendicular to the
axis of rotation of the body from proximate to the axis of rotation
of the body radially outward. A second section of the profile of
the face surrounding and extending radially outward from the first
section may be linear and may extend at a second, different slope
relative to the plane perpendicular to the axis of rotation of the
body. A third section of the profile may be located radially
outward from the second section, the third section arcing from the
second slope away from a leading end of the body.
[0011] In still other embodiments, earth-boring tools may include a
body having blades extending outward from a remainder of the body.
Cutting elements may be secured to the blades. A profile formed by
a least squares fit to outermost points of cutting faces of the
cutting elements secured may be oriented at an angle of at least
15.degree. relative to a plane perpendicular to an axis of rotation
of the body at a location proximate to an axis of rotation of the
body.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] While this disclosure concludes with claims particularly
pointing out and distinctly claiming specific embodiments, various
features and advantages of embodiments within the scope of this
disclosure may be more readily ascertained from the following
description when read in conjunction with the accompanying
drawings, in which:
[0013] FIG. 1 is a perspective view an earth-boring tool;
[0014] FIGS. 2A through 2D are schematics of profiles for cutting
elements of an earth-boring tool, such as that shown in FIG. 1;
[0015] FIG. 3 is a schematic of two embodiments of profiles for
cutting elements for an earth-boring tool, such as that shown in
FIG. 1; and
[0016] FIG. 4 is a schematic of yet another embodiment of a profile
for cutting elements of an earth-boring tool, such as that shown in
FIG. 1.
DETAILED DESCRIPTION
[0017] The illustrations presented in this disclosure are not meant
to be actual views of any particular earth-boring tool or component
thereof, but are merely idealized representations employed to
describe illustrative embodiments. Thus, the drawings are not
necessarily to scale.
[0018] As used herein, the term "configured" refers to a size,
shape, material composition, and/or 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.
[0019] As used herein, the terms "substantially" and "about" 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. For example, a parameter that is substantially or about
a specified value may be at least about 90% the specified value, at
least about 95% the specified value, at least about 99% the
specified value, or even at least about 99.9% the specified
value.
[0020] As used herein, the term "earth-boring tool" means and
includes any type of bit or tool used for drilling during the
formation or enlargement of a wellbore in a subterranean formation.
For example, earth-boring tools include fixed-cutter drill bits,
percussion bits, core bits, eccentric bits, bi-center bits,
reamers, mills, hybrid bits, and other drilling bits and tools
known in the art.
[0021] The inventors herein have discovered that, in addition to
the form, orientation and positioning of the PDC cutting elements
on the bit face, the profile of the bit and particularly the
profile portion from the nose through the cone to the bit
centerline greatly impact bit durability and ROP. Therefore, the
form and positioning of the cutting elements and the design of the
bit body are thus are significant to improving ROP and durability
of a drill bit.
[0022] FIG. 1 shows a perspective view of an earth-boring tool 100.
The earth-boring tool 100 may include a body 102 having blades 104
extending outward from a remainder of the body 102 with junk slots
114 located rotationally between the blades 104. The blades 104 may
extend radially outward from proximate to the axis of rotation 110
of the earth-boring tool 100 to a gage region 118 at an outer
diameter of the body 102. The blades 104 may extend longitudinally
from a face 116 of the body 102 at a leading end of the
earth-boring tool 100, away from the face 116, toward a shank 120
at a trailing end of the earth-boring tool 100. The shank 120 may
have a threaded connection portion, which may conform to industry
standards (e.g., those promulgated by the American Petroleum
Institute (API)), for attaching the earth-boring tool 100 to a
drill string. The body 102 may include a material suitable for
downhole use. For example, the body 102 may include a metal or
metal alloy material (e.g., steel) or a particle-matrix composite
material (e.g., particles of tungsten carbide located in a metal or
metal alloy matrix).
[0023] Cutting elements 112 may be secured to the body 102. More
specifically, the cutting elements 112 may be secured at least
partially within pockets 122 extending from rotationally leading
surfaces of a blade 104 into the blade 104. The cutting elements
112 may be configured to engage with the formation under WOB, and
remove formation material during rotation of the earth-boring tool
100. Nozzles 124 located within the junk slots 114 may emit
drilling fluid circulating through the drill string under pressure
to remove cuttings from the cutting elements 112 and the bit face
and carry the cuttings suspended in the drilling fluid up the
wellbore annulus to the surface. The cutting elements 112 of the
earth-boring tool 100 may have a profile 106 according to an
embodiment of the disclosure, which profile 106 may best be shown
by projecting cutting faces 134 of the cutting elements 112
rotationally onto a common plane 108 to one side of an axis of
rotation 110, which may also be characterized as the longitudinal
axis, of the earth-boring tool 100. The profile 106 may then be
formed by identifying the outermost points of the cutting faces 134
of the cutting elements 134, the outermost points being located
farthest from the body 102, and calculating a least squares fit for
those points. Profiles 106 for cutting elements 112 of earth-boring
tools 100 in accordance with this disclosure may reduce the work
rate for individual cutting elements 112 secured to face 116 of the
earth-boring tool 100, may improve stability of the earth-boring
tool 100 during drilling, and may better distribute loads borne
across the radial extent of the profile 106 without significantly
worsening performance, in terms of rate of penetration (ROP) of the
earth-boring tool 100. The earth-boring tool 100 depicted in FIG. 1
is configured as a fixed-cutter drill bit having cutting elements
112 secured to the blades 104 thereof, but other configurations for
earth-boring tools employing fixed cutting elements may be employed
with a profile 106 for cutting elements 112 in accordance with this
disclosure.
[0024] FIGS. 2A through 2D are schematic embodiments of profiles
106 for cutting elements 112 of an earth-boring tool, such as the
earth-boring tool 100 shown in FIG. 1. The profiles 106A through
106D of FIGS. 2A through 2D may collectively follow a parabolic
trajectory 126 from proximate to the axis of rotation 110 of the
earth-boring tool 100 (see FIG. 1), radially outward, to a nose
point 128. At the nose point 128, a slope of the profiles 106A
through 106D as measured relative to a plane 130 extending
perpendicular to the axis of rotation 110 may be such that an angle
between tangent lines to the profiles 106A through 106 D and the
plane 130 at the nose point 128 may be, for example, less than
about 5.degree.. More specifically, a line extending tangent to a
surface of the blades 104 at the nose point 128 may be, for
example, about 0.degree.. From the nose point 128, the profile 106
may extend radially outward to the gage region 118 (see FIG. 1)
while curving longitudinally toward the shank 120 (see FIG. 1). The
nose point 128 may be located at least one-half of a radius of the
earth-boring tool 100 (see FIG. 1) away from the axis of rotation
110. More specifically, the nose point 128 may be located between
about one-half and about three-fourths of the radius of the
earth-boring tool 100 (see FIG. 1) from the axis of rotation.
[0025] The outer surface of each blade 104A through 104D in the
region extending radially from the axis of rotation 110 to the nose
point 128 may include one or more planes 132A through 132D
extending radially outward from the axis of rotation 110 toward the
nose point 128, and extending longitudinally at an oblique angle
relative to the plane 130 perpendicular to the axis of rotation
110. For example, the outer surface of each blade 104A through 104D
may include a number of planes 132A through 132D equal to a number
of cutting elements 112A through 112D located in the region
extending radially from the axis of rotation 110 to the nose point
128, each cutting element 112A through 112D located on a
corresponding one of the planes 132A through 132D. More
specifically, the total number of planes 132A through 132D deployed
on all the blades 104A through 104D of a given earth-boring tool
may be at least five. Each plane 132A through 132D may be oriented
tangent to the parabolic trajectory 126 at a point of intersection
between the surface of the respective plane 132A through 132D and a
line 136A through 136D extending from a point on a cutting face
134A through 134D of a corresponding cutting element 112A, through
112D farthest from the blade 104A through 104D within the plane
132A through 132D, to the respective plane 132A through 132D in a
direction perpendicular to the plane 132A through 132D. When the
planes 132A through 132D of the blades 104A through 104D are
projected rotationally onto the plane 108 (see FIG. 1) containing
the axis of rotation 110, the parabolic trajectory 126 may contact
each of the planes 132A through 132D, such that the planes 132A
through 132D lie tangent to the parabolic trajectory. Moreover, a
curve 138 formed by a least squares fit to a series of points
generated by rotationally projecting each of the cutting elements
112A through 112D within the region extending radially from the
axis of rotation 110 to the nose point 128 onto the plane 108 (see
FIG. 1) in which the axis of rotation 110 is located and placing
the points at the points on the cutting faces 134A through 134D of
the cutting elements 112A through 112D farthest from the surfaces
of the blades 104A through 104D within the region may be a
parabola.
[0026] Because the cutting elements 112A through 112D may be
located at different radial distances from the axis of rotation
110, the specific slopes of the planes 132A through 132D relative
to the plane 130 perpendicular to the axis of rotation 110 may
vary. For example, the slopes of the planes 132A through 132D
relative to the plane 130 perpendicular to the axis of rotation 110
may be such that angles between the planes 132A through 132D and
the plane 130 perpendicular to the axis of rotation 110 may vary
from about 35.degree. or less proximate to the axis of rotation 110
to greater than about 0.degree. proximate to the nose point 128.
More specifically, the slopes of the planes 132A through 132D
relative to the plane 130 perpendicular to the axis of rotation 110
may be such that angles between the planes 132A through 132D and
the plane 130 perpendicular to the axis of rotation 110 may vary
from about 30.degree. or less proximate to the axis of rotation 110
to about 5.degree. or more (e.g., about 10.degree. or more, about
15.degree. or more, etc.) proximate to the nose point 128. The
parabolic trajectory 126 followed by the planes 132A through 132D
of the blades 104A through 104D, and the parabolic curve 138
followed by the cutting elements 112A through 112D, may enable the
region proximate to the axis of rotation 110 to extend more rapidly
toward the shank 120 (see FIG. 1), while the parabolic trajectory
126 and the parabolic curve 138 may more gradually transition from
the steep region proximate to the axis of rotation 110 to the nose
point 128.
[0027] FIG. 3 is a schematic of embodiments of two additional
profiles 106E and 106F for cutting elements 112 (see FIG. 1) for an
earth-boring tool, such as the earth-boring tool 100 shown in FIG.
1. As shown in FIG. 3, another profile 106E for cutting elements
112 (see FIG. 1) in accordance with this disclosure may follow a
parabolic trajectory 126 in the region extending from the axis of
rotation 110 of the earth-boring tool 100 to the nose point 128. As
with the previous embodiment, the nose point 128 may be at a
location where a slope of the profile 106E may be such that an
angle from a line tangent to the profile 106E as measured relative
to a plane 130 extending perpendicular to the axis of rotation 110
may be, for example, less than about 5.degree.. More specifically,
the nose point 128 may be located where a line extending tangent to
a curve 138 defining the profile 106E, and formed by a least
squares fit to a series of points generated by rotationally
projecting each of the cutting elements 112 (see FIG. 1) onto the
plane 108 (see FIG. 1) in which the axis of rotation 110 is located
and placing the points on the cutting faces 134A through 134D of
the cutting elements 112A through 112D farthest from the surfaces
of the blades 104A through 104D within the region, may be, for
example, about 0.degree.. From the nose point 128, the profile 106E
may extend radially outward to the gage region 118 (see FIG. 1)
while curving longitudinally toward the shank 120 (see FIG. 1).
[0028] Unlike the outer surfaces of the blades 104A through 104D
shown in FIGS. 2A through 2D, which included planes 132A through
132D extending tangent to the parabolic trajectory 126, the outer
surface of at least one of the blades 104E shown in FIG. 3 may
itself be parabolic. More specifically, the outer surface of the
blade 104E when projected rotationally onto the plane 108 (see FIG.
1) in which the axis of rotation 110 is located may be a parabola
from immediately proximate to the axis of rotation 110 to the nose
point 128, with substantially no linear portions.
[0029] A slope of the curve 138 defining the profile 106E relative
to the plane 130 perpendicular to the axis of rotation 110, as
quantified by measuring an angle between a line tangent to the
outer surface and the plane 130 perpendicular to the axis of
rotation 110, may vary from about 35.degree. or less proximate to
the axis of rotation 110 to about 0.degree. or more proximate to
the nose point 128. More specifically, the slope of the curve 138
defining the profile 106E relative to the plane 130 perpendicular
to the axis of rotation 110 may be such that the angle between the
line tangent to the outer surface and the plane 130 vary from about
30.degree. or less proximate to the axis of rotation 110 to about
5.degree. or more (e.g., about 10.degree. or more, about 15.degree.
or more, etc.) proximate to the nose point 128. The slope of the
curve 138 defining the profile 106E relative to the plane 130
perpendicular to the axis of rotation 110 may vary continuously
from proximate to the axis of rotation 110 to proximate to the nose
point 128, forming a parabola. The parabolic trajectory 126
followed by the profile 106E of the blade 104, and the parabolic
curve 138 followed by the cutting elements 112 (see FIG. 1) secured
thereto, may enable the region proximate to the axis of rotation
110 to extend more rapidly toward the shank 120 (see FIG. 1), while
the parabolic trajectory 126 and the parabolic curve 138 may more
gradually transition from the steep region proximate to the axis of
rotation 110 to the nose point 128.
[0030] The other profile 106F shown in FIG. 3 may be characterized
by a linear portion 125 of the profile 106F exhibiting a steep
slope extending from proximate to the axis of rotation 110,
radially outward, to proximate to the nose point 128. From the nose
point 128, the profile 106F may extend radially outward to the gage
region 118 (see FIG. 1) while curving longitudinally toward the
shank 120 (see FIG. 1). A slope of a linear portion 125 of the
profile 106F relative to the plane 130 perpendicular to the axis of
rotation 110 may be such that an angle between the linear portion
125 and the plane 130 may be, for example, between about 35.degree.
and about 10.degree.. More specifically, the slope of the linear
portion 125 of the profile 106F relative to the plane 130
perpendicular to the axis of rotation 110 may be such that the
angle between the linear portion 125 and the plane 130 may be
between about 30.degree. and about 15.degree.. The steep slope of
the linear portion 125 of the profile 106F in the region extending
from proximate to the axis of rotation 110, radially outward, to
proximate to the nose point 128 may enable the region proximate to
the longitudinal axis of rotation 110 to extend more rapidly toward
the shank 120 (see FIG. 1). The profile 106F may be generated by,
for example, forming a least squares fit to a series of points
identified by rotationally projecting each of the cutting elements
112 (see FIG. 1) onto the plane 108 (see FIG. 1) in which the axis
of rotation 110 is located and placing the points on the cutting
faces 134 (see FIG. 1) of the cutting elements 112 (see FIG. 1)
farthest from the surfaces of the blades 104 (see FIG. 1).
[0031] In some embodiments employing the steep linear trajectory
for the profile 106F of the cutting elements 112 proximate to the
axis of rotation 110, the nose point 128 may be located on a planar
nose surface 127. For example, the surfaces of the blades 104 (see
FIG. 1) producing the linear portion 125 of the profile 106F, which
may themselves be planar, may intersect with another planar nose
surface 127 at an edge. The nose surface 127 may extend radially
outward from the surfaces of the blades 104 (see FIG. 1) producing
the steep linear portion 125 of the profile 106F at a slope such
that an angle between the nose surface 127 and the plane 130
extending perpendicular to the axis of rotation 110 may be less
than about 5.degree.. More specifically, the slope of the nose
surface 127 may be such that the angle between the nose surface 127
and the plane 130 extending perpendicular to the axis of rotation
110 may be, for example, about 0.degree.. From the nose surface
127, the surfaces of the blades 104 may extend radially outward to
the gage region 118 (see FIG. 1) while curving longitudinally
toward the shank 120 (see FIG. 1).
[0032] FIG. 4 is a schematic of yet another embodiment of a profile
106G of cutting elements 112 (see FIG. 1) for an earth-boring tool,
such as the earth-boring tool 100 shown in FIG. 1. The profile 106G
shown in FIG. 3 may be characterized by a first linear section 140
exhibiting a steeper slope extending from proximate to the axis of
rotation 110 radially outward to a second linear section 142, the
second linear section 142 extending from the first linear section
140 at a shallower slope to or proximate to the nose point 128. As
with the previous embodiment, the nose point 128 may be at a
location where a slope of the profile 106G may be at or proximate a
minimum, as quantified by measuring an angle between a line tanged
to the profile 106G at the nose point and a plane 130 extending
perpendicular to the axis of rotation 110, which may be, for
example, less than about 5.degree.. More specifically, the nose
point 128 may be located where a line extending tangent to the
profile 106G may be, for example, about 0.degree.. From the nose
point 128, the profile 106G may extend radially outward to the gage
region 118 (see FIG. 1) while curving longitudinally toward the
shank 120 (see FIG. 1). The profile 106G may be generated by, for
example, forming a least squares fit to a series of points
corresponding to locations on the cutting faces 134 (see FIG. 1) of
the cutting elements 112 (see FIG. 1) farthest from the surfaces of
the blades 104 (see FIG. 1) when the cutting faces 134 (see FIG. 1)
are rotationally projected onto the plane 108 (see FIG. 1) in which
the axis of rotation 110 is located.
[0033] A slope of the first linear section 140 of the profile 106G
relative to the plane 130 perpendicular to the axis of rotation 110
may be such that an angle between the first linear section 140 and
the plane 130 may be, for example, between about 35.degree. and
about 5.degree.. More specifically, the slope of the first linear
section 140 of the profile 106G relative to the plane 130
perpendicular to the axis of rotation 110 may be such that an angle
between the first linear section 140 and the plane 130 may be, for
example, between about 30.degree. and about 10.degree.. A first
radial distance R.sub.1 over which the first linear section 140
extends, as measured from the axis of rotation 110 in a direction
perpendicular to the axis of rotation 110, may be, for example,
between about 50% and about 75% of a second radial distance R.sub.2
to the nose point 128. More specifically, the first radial distance
R.sub.1 over which the first linear section 140 extends may be, for
example, between about 60% and about 70% (e.g., about 66%) of the
second radial distance R.sub.2 to the nose point 128. A slope of
the second linear section 142 of the profile 106G relative to the
plane 130 perpendicular to the axis of rotation 110 may be less
than the slope of the first linear section 140. For example, the
slope of the second linear section 142 relative to the plane 130
perpendicular to the axis of rotation 110 may be between about 25%
and about 50% of the slope of the first linear section 140. More
specifically, the slope of the second linear section 142 relative
to the plane 130 perpendicular to the axis of rotation 110 may be
between about 30% and about 40% (e.g., about 33%) of the slope of
the first linear section 140. As an additional example, the slope
of the second linear section 142 relative to the plane 130
perpendicular to the axis of rotation 110 may be such that an angle
between the second linear section 142 and the plane 130 may be
between about 10.degree. and about 20.degree.. More specifically,
the slope of the second linear section 142 relative to the plane
130 perpendicular to the axis of rotation 110 may be such that an
angle between the second linear section 142 and the plane 130 may
be between about 12.degree. and about 18.degree. (e.g., about
15.degree.). The first slope of the first linear section 140 may
be, for example, about one-and-a-half to five times as great as the
second slope of the second linear section 142 relative to the plane
perpendicular to the axis of rotation of the body. More
specifically, the first slope of the first linear section 140 may
be, for example, about two to four times (e.g., two-and-a-half
times, three times, three-and-a-half times) as great as the second
slope of the second linear section 142 relative to the plane
perpendicular to the axis of rotation of the body. The steeper
slope of the first linear section 140 may enable the region
proximate to the axis of rotation 110 to extend more rapidly toward
the shank 120 (see FIG. 1), while the more gradual slope of the
second linear section 142 may more gradually transition from the
steep region proximate to the axis of rotation 110 to the nose
point 128.
[0034] Profiles for outermost points of cutting elements of
earth-boring tools in accordance with this disclosure may exhibit a
deeper cone region immediately surrounding the axis of rotation. As
a result a greater quantity of the formation material being drilled
may be received into the cone region, and the sloped surfaces of
the blades may better grip that larger quantity of formation
material, increasing stability. In addition, the inventors have
found that providing a more gradual transition from the steeper
slope in the region proximate to the axis of rotation to a
shallower slope proximate to the nose point more evenly balances
work rates across the face of the tool. Impact loading of cutting
elements following profiles in accordance with this disclosure may
also be reduced. The inventors have also found through their
modeling of the behavior of an earth-boring tool including profiles
for cutting elements in accordance with this disclosure that
maximum stresses within the blades are more evenly balanced from
blade to blade. Because the slope of the transition between cutting
elements secured to the blades is steeper in the cone region, the
junk slots within that region may be shallower than in other
regions. However, modeling of the fluid flow from the nozzles to
clear cuttings reveals that the shallower junk slots do not have a
significant deleterious effect on the efficiency with which the
fluid clears the cuttings. Finally, earth-boring tools employing
profiles in accordance with this disclosure may more evenly
distribute a given applied weight (e.g., weight-on-bit) across all
the cutting elements.
[0035] Additional, nonlimiting embodiments within the scope of this
disclosure include the following:
Embodiment 1
[0036] An earth-boring tool comprising: a body comprising blades
projecting therefrom, the blades extending generally radially
outwardly from an axis of rotation of the tool; and cutting
elements secured to the blades; wherein a profile of the cutting
elements secured to the blades intersecting outermost points of
cutting faces of the cutting elements as viewed projected
rotationally onto a plane, within which an axis of rotation of the
body is located, is parabolic from immediately proximate the axis
of rotation to a nose point at which a slope of the line is such
that an angle between the line and a plane perpendicular to the
axis of rotation is about 0.degree..
Embodiment 2
[0037] The earth-boring tool of Embodiment 1, wherein a slope of
the profile proximate to the axis of rotation of the body is such
that an angle between the line and a plane perpendicular to the
axis of rotation is at least about 15.degree..
Embodiment 3
[0038] The earth-boring tool of Embodiment 1 or Embodiment 2,
wherein a slope of the profile proximate to the axis of rotation of
the body is such that an angle between the line and a plane
perpendicular to the axis of rotation is about 35.degree. or
less.
Embodiment 4
[0039] The earth-boring tool of any one of Embodiments 1 through 3,
wherein the nose point is located at least one-half of a radius of
the body from the axis of rotation.
Embodiment 5
[0040] The earth-boring tool of any one of Embodiments 1 through 4,
wherein the nose point is located at less than three-fourths of a
radius of the body from the axis of rotation.
Embodiment 6
[0041] The earth-boring tool of any one of Embodiments 1 through 5,
wherein surfaces of the blades as projected onto the plane
perpendicular to the direction of rotation of the blades comprise a
plurality of line segments, each line segment extending tangent to
a parabolic curve extending from proximate to the axis of rotation
to proximate to the nose point.
Embodiment 7
[0042] The earth-boring tool of Embodiment 6, wherein a number of
the line segments is at least five.
Embodiment 8
[0043] An earth-boring tool comprising: a body comprising blades
extending outward from a remainder of the body; and cutting
elements secured to the blades; wherein a first section of a
profile of a face formed by a least squares fit to outermost points
of cutting faces of the cutting elements secured to the blades as
viewed projected rotationally onto a plane, within which plane an
axis of rotation of the body is located, may be linear and may
extend at a first slope relative to a plane perpendicular to the
axis of rotation of the body from proximate to the axis of rotation
of the body radially outward; wherein a second section of the
profile of the face surrounding and extending radially outward from
the first section may be linear and may extend at a second,
different slope relative to the plane perpendicular to the axis of
rotation of the body; and wherein a third section of the profile
may be located radially outward from the second section, the third
section arcing from the second slope away from a leading end of the
body.
Embodiment 9
[0044] The earth-boring tool of Embodiment 8, wherein the first
slope is two to four times as great as the second slope relative to
the plane perpendicular to the axis of rotation of the body.
Embodiment 10
[0045] The earth-boring tool of Embodiment 8 or Embodiment 9,
wherein the first slope is such that an angle between the first
section and a plane perpendicular to the axis of rotation is
between about 10.degree. and about 35.degree. relative to the plane
perpendicular to an axis of rotation of the body.
Embodiment 11
[0046] The earth-boring tool of any one of Embodiments 8 through
10, wherein the second slope is such that an angle between the
second section and a plane perpendicular to the axis of rotation is
between about 10.degree. and about 20.degree. relative to the plane
perpendicular to the axis of rotation of the body.
Embodiment 12
[0047] The earth-boring tool of any one of Embodiments 8 through
11, wherein a transition between the first slope and the second
slope occurs a radial distance at least about one-half of a radial
distance occupied by the first and second slopes.
Embodiment 13
[0048] The earth-boring tool of any one of Embodiments 8 through
12, wherein a transition between the first slope and the second
slope occurs a radial distance less than about three-fourths of a
radial distance occupied by the first and second slopes.
Embodiment 14
[0049] An earth-boring tool comprising: a body comprising blades
extending outward from a remainder of the body; and cutting
elements secured to the blades; wherein a profile formed by a least
squares fit to outermost points of cutting faces of the cutting
elements secured is oriented at an angle of at least 15.degree.
relative to a plane perpendicular to an axis of rotation of the
body at a location proximate to an axis of rotation of the
body.
Embodiment 15
[0050] The earth-boring tool of Embodiment 14, the profile is
oriented at an angle of about 30.degree. or less relative to the
plane perpendicular to the axis of rotation at the location
proximate to the axis of rotation.
Embodiment 16
[0051] The earth-boring tool of Embodiment 14 or Embodiment 15,
wherein the profile is parabolic from immediately proximate the
axis of rotation to a nose point at which a slope of the profile is
such that an angle between a line tangent to the profile and a
plane perpendicular to the axis of rotation is about 0.degree..
Embodiment 17
[0052] The earth-boring tool of Embodiment 16, wherein the nose
point is located at least one-half of a radius of the body from the
axis of rotation.
Embodiment 18
[0053] The earth-boring tool of Embodiment 16, wherein the nose
point is located at less than three-fourths of a radius of the body
from the axis of rotation.
Embodiment 19
[0054] The earth-boring tool of Embodiment 14, wherein surfaces of
the blades as projected onto a plane perpendicular to a direction
of rotation of the blades comprise a plurality of line segments,
each line segment extending tangent to a parabolic curve extending
from proximate to the axis of rotation to proximate to the nose
point.
Embodiment 20
[0055] The earth-boring tool of Embodiment 19, wherein a number of
the line segments is at least five.
[0056] While certain illustrative embodiments have been described
in connection with the figures, those of ordinary skill in the art
will recognize and appreciate that the scope of this disclosure is
not limited to those embodiments explicitly shown and described in
this disclosure. Rather, many additions, deletions, and
modifications to the embodiments described in this disclosure may
be made to produce embodiments within the scope of this disclosure,
such as those specifically claimed, including legal equivalents. In
addition, features from one disclosed embodiment may be combined
with features of another disclosed embodiment while still being
within the scope of this disclosure, as contemplated by the
inventors.
* * * * *