U.S. patent application number 13/014673 was filed with the patent office on 2011-07-28 for drilling assembly with underreaming bit and method of use.
Invention is credited to Timothy W. Conn.
Application Number | 20110180330 13/014673 |
Document ID | / |
Family ID | 44308108 |
Filed Date | 2011-07-28 |
United States Patent
Application |
20110180330 |
Kind Code |
A1 |
Conn; Timothy W. |
July 28, 2011 |
DRILLING ASSEMBLY WITH UNDERREAMING BIT AND METHOD OF USE
Abstract
Embodiments provide apparatuses and methods for drilling and
underreaming, particularly to underreamer expansion bits.
Underreamer drill assemblies and underreaming bits manufactured in
accordance with various embodiments may help to resist
over-excavating or undermining, which may result in a more stable
bore hole.
Inventors: |
Conn; Timothy W.; (Veneta,
OR) |
Family ID: |
44308108 |
Appl. No.: |
13/014673 |
Filed: |
January 26, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61298490 |
Jan 26, 2010 |
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Current U.S.
Class: |
175/406 |
Current CPC
Class: |
E21B 10/32 20130101 |
Class at
Publication: |
175/406 |
International
Class: |
E21B 10/26 20060101
E21B010/26 |
Claims
1. An underreamer drill assembly comprising: a center shaft having
a central axis, a proximal end, and a distal end, wherein the
center shaft is configured to receive drive energy from a driver at
the proximal end and adapted to couple to a bit body at the distal
end; a bit body adapted to couple to the center shaft and
configured to couple to at least one underreamer arm; and at least
one underreamer arm configured to underream a bore hole having a
side wall, wherein the center shaft, bit body, and underreamer arm
form a distal cutting face that is substantially perpendicular to
the central axis, and wherein the underreamer drill assembly is
configured to direct air, water, or flush media substantially away
from the side wall of the bore hole.
2. The underreamer drill assembly of claim 1, wherein the center
shaft and bit body are adapted to direct air, water, or flush media
substantially along the central axis and perpendicular to the
distal cutting face.
3. The underreamer drill assembly of claim 1, wherein the center
shaft and bit body are adapted to direct air, water, and flush
media substantially along the central axis and perpendicular to the
distal cutting face.
4. The underreamer drill assembly of claim 1, wherein the at least
one underreamer arm is configured to be extended against the side
wall of the bore hole.
5. The underreamer drill assembly of claim 1, wherein the at least
one underreamer arm comprises a distal pilot surface, a proximal
upper surface, and an axial height spanning the distance between
the distal pilot surface and the proximal upper surface.
6. The underreamer drill assembly of claim 5, wherein the axial
height is less than 8 inches.
7. The underreamer drill assembly of claim 5, wherein the axial
height is less than 6 inches.
8. The underreamer drill assembly of claim 5, wherein the axial
height is between about 2 and about 4 inches.
9. The underreamer drill assembly of claim 1, wherein the distal
cutting face comprises a plurality of compact cutting inserts.
10. The underreamer drill assembly of claim 9, wherein the compact
cutting inserts are replaceable.
11. The underreamer drill assembly of claim 9, wherein the compact
cutting inserts comprise carbide buttons.
12. The underreamer drill assembly of claim 1, wherein the center
shaft, bit body, and underreamer arms are modular.
13. The underreamer drill assembly of claim 12, wherein the bit
body is adapted to be removed and replaced with a second bit body
having a different diameter.
14. The underreamer drill assembly of claim 12, wherein the center
shaft is adapted to be removed and replaced with a second center
shaft that is adapted to couple to a different drive mechanism.
15. The underreamer drill assembly of claim 1, wherein the center
shaft comprises a drive adapter.
16. The underreamer drill assembly of claim 15, wherein the drive
adapter is configured to receive rotational torque, impact energy,
vibration, or linear feed force from a drive mechanism.
17. The underreamer drill assembly of claim 16, wherein the adapter
is configured to move the center shaft in response to the
rotational torque, impact energy, vibration, or linear feed
force.
18. The underreamer drill assembly of claim 16, wherein the drive
mechanism is a down hole hammer or a drill rod for hydraulic
hammer.
19. The underreamer drill assembly of claim 1, wherein the center
shaft is adapted at or near the distal end to couple to the bit
body via a hex or spline drive mechanism.
20. An underreamer drill assembly comprising: a center shaft having
a central axis, a proximal end, and a distal end, wherein the
center shaft is configured to receive drive energy from a driver at
the proximal end and adapted to couple to a bit body via a hex
drive mechanism at the distal end; a bit body adapted to couple to
the center shaft via the hex drive mechanism and configured to
couple to at least one underreamer arm; and at least one
underreamer arm configured to underream a bore hole having a side
wall; wherein the center shaft, bit body, and underreamer arm form
a distal cutting face that is substantially perpendicular to the
central axis; wherein the underreamer drill assembly is configured
to direct air, water, or flush media substantially along the
central axis and perpendicular to the distal cutting face; and
wherein the center shaft is configured to transmit drive energy
from the driver to the at least one arm and move the at least one
arm from a retracted position to an extended position.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to U.S. Patent
Application No. 61/298,490, filed Jan. 26, 2010, entitled "DRILL
ASSEMBLY WITH UNDERREAMING BIT AND METHOD OF USE," the entire
disclosure of which is hereby incorporated by reference in its
entirety.
TECHNICAL FIELD
[0002] Embodiments herein relate to the field of excavation, and,
more specifically, to apparatus and methods for drilling and
underreaming.
BACKGROUND
[0003] Underreaming is an excavation technique used in boring and
in installing piles or steel casings. For instance, underreaming
may be used to enlarge or ream a borehole beneath a string of
casing or drivepipe. Expansion bits are useful for underreaming,
but when different strata are encountered, particularly
unconsolidated formations such as sand, gravel, clay, and water,
conventional expansion underreamers can cause undermining or
over-excavating of loose materials. This can undermine the
stability of the hole.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Embodiments will be readily understood by the following
detailed description in conjunction with the accompanying drawings.
Embodiments are illustrated by way of example and not by way of
limitation in the figures of the accompanying drawings.
[0005] FIG. 1 illustrates a side view of an underreamer assembly
with arms in the extended position, in accordance with various
embodiments;
[0006] FIG. 2 illustrates a side view of an underreamer assembly
with arms in the retracted position, in accordance with various
embodiments;
[0007] FIG. 3 illustrates an exploded view of an underreamer
assembly, in accordance with various embodiments;
[0008] FIG. 4 illustrates a side view of a center shaft, in
accordance with various embodiments;
[0009] FIG. 5 illustrates a cross-sectional view of a center shaft,
in accordance with various embodiments;
[0010] FIG. 6 illustrates a perspective view of a center shaft, in
accordance with various embodiments;
[0011] FIGS. 7A, 7B, and 7C illustrate a side view of a bit body
(FIG. 7A), a side view of a spring retainer (FIG. 7B) and cross
sectional view of a bit body (FIG. 7C), in accordance with various
embodiments;
[0012] FIG. 8 illustrates a perspective view of a bit body, in
accordance with various embodiments;
[0013] FIGS. 9A, 9B, and 9C illustrate a perspective view (FIG.
9A), side view (FIG. 9B), and back view (FIG. 9C) of an arm, in
accordance with various embodiments;
[0014] FIG. 10 illustrates a cross-sectional view of a center shaft
with the air flow pathway indicated, in accordance with various
embodiments;
[0015] FIG. 11 illustrates a face view of the underreamer assembly
in the extended position, in accordance with various
embodiments;
[0016] FIG. 12 illustrates a perspective view of the assembly of
various interchangeable components, in accordance with various
embodiments;
[0017] FIG. 13 illustrates a perspective view of the flow of flush
media through an exemplary underreamer assembly, in accordance with
various embodiments;
[0018] FIG. 14 illustrates a cross-sectional view of the flow of
flush media through an exemplary underreamer assembly, in
accordance with various embodiments;
[0019] FIG. 15 illustrates a side view of an alternate embodiment
of the underreamer assembly configured to be driven by a hex drive
mechanism, in accordance with various embodiments;
[0020] FIGS. 16A, 16B, 16C, and 16D illustrate a side view of an
embodiments of a bit body (FIG. 16A), a side view of a spring
retainer (FIG. 16B), a cross sectional view of a bit body (FIG.
16C), and a transverse cross sectional view of a bit assembly (FIG.
16D), all components of a bit assembly configured for use with a
hex drive mechanism, in accordance with various embodiments;
[0021] FIG. 17 illustrates a side view of another alternate
embodiment of the underreamer assembly configured to be driven by a
hex drive mechanism, in accordance with various embodiments;
and
[0022] FIG. 18 illustrates a cross sectional view of components of
a bit assembly configured for use with a hex drive mechanism, in
accordance with various embodiments.
DETAILED DESCRIPTION OF DISCLOSED EMBODIMENTS
[0023] In the following detailed description, reference is made to
the accompanying drawings which form a part hereof, and in which
are shown by way of illustration embodiments that may be practiced.
It is to be understood that other embodiments may be utilized and
structural or logical changes may be made without departing from
the scope. Therefore, the following detailed description is not to
be taken in a limiting sense, and the scope of embodiments is
defined by the appended claims and their equivalents.
[0024] Various operations may be described as multiple discrete
operations in turn, in a manner that may be helpful in
understanding embodiments; however, the order of description should
not be construed to imply that these operations are order
dependent.
[0025] The description may use perspective-based descriptions such
as up/down, back/front, and top/bottom. Such descriptions are
merely used to facilitate the discussion and are not intended to
restrict the application of disclosed embodiments.
[0026] The terms "coupled" and "connected," along with their
derivatives, may be used. It should be understood that these terms
are not intended as synonyms for each other. Rather, in particular
embodiments, "connected" may be used to indicate that two or more
elements are in direct physical or electrical contact with each
other. "Coupled" may mean that two or more elements are in direct
physical or electrical contact. However, "coupled" may also mean
that two or more elements are not in direct contact with each
other, but yet still cooperate or interact with each other.
[0027] For the purposes of the description, a phrase in the form
"A/B" or in the form "A and/or B" means (A), (B), or (A and B). For
the purposes of the description, a phrase in the form "at least one
of A, B, and C" means (A), (B), (C), (A and B), (A and C), (B and
C), or (A, B and C). For the purposes of the description, a phrase
in the form "(A)B" means (B) or (AB) that is, A is an optional
element.
[0028] The description may use the terms "embodiment" or
"embodiments," which may each refer to one or more of the same or
different embodiments. Furthermore, the terms "comprising,"
"including," "having," and the like, as used with respect to
embodiments, are synonymous.
[0029] In various embodiments, methods, apparatuses, and systems
for underreaming are provided. Embodiments herein provide
underreaming devices, such as bits and bit assemblies, and methods
for drilling and underreaming that overcome the shortcomings of
conventional underreaming devices. Among other things, underreamers
may be useful for a variety of excavation tasks, such as expanding
well bores, for instance to increase the yield of the well; for
straightening a bend in a hole, which may prevent the advancement
of a pile or casing; and/or for excavating tie-back or anchor holes
in any type of dirt, rock, or concrete formations.
[0030] Underreamers typically have cutting members that are
designed to be moved or extended against a well bore wall after the
tool is positioned within the well bore. However, such underreamers
typically have an air or fluid media flow pattern that forces air
or fluid media to exit the bit assembly in a lateral direction,
e.g., against the sides of the hole. This may be problematic when
excavating different strata, particularly unconsolidated formations
such as sand, gravel, clay, and water, as the pressure and
turbulence of the media can undesirably enlarge the hole in an
uneven fashion depending on the solidity of the strata. These
unconsolidated soil conditions may occur deep in the hole, for
instance, beneath rock strata, and conventional expansion
underreamers may therefore cause undermining or over-excavating of
the loose materials without the knowledge of the operator. This may
undermine the stability of the hole and/or any casing, footing, or
pile contained therein. By contrast, the underreamers provided
herein in various embodiments may provide a substantially vertical
downward media flow pattern through the bottom of the bit, which
prevents over-excavation from lateral flow and/or turbulence, and
which may increase the stability of the resulting hole.
[0031] Another advantage of the disclosed underreamer devices is
that it may have a short vertical distance between the pilot area
of the cutting face (e.g., the distal-most portion of the bit) and
the proximal edges of the underreaming arms. On a conventional
underreaming bit, this distance is about 8-10 inches, requiring the
pilot area of the bit to advance that distance in front of the
underreaming zone. On the disclosed underreaming bits, this
distance may be much shorter, for example, about four, three, or
two inches, or even less. In various embodiments, reducing this
distance may reduce the mass of the bit, which increases the energy
transformation into the drill, making for a more effective boring
mechanism.
[0032] In various embodiments, the shorter working distance between
the pilot area of the cutting face and the underreaming arms also
may increase the efficacy of the underreaming action. When a pile
is being driven into the ground and becomes obstructed by a
boulder, an underreamer may be used to remove the obstruction and
allow the pile to continue to advance. However, if there is a long
working distance between the pilot area and the underreaming arms,
it may not be possible to advance the underreaming assembly far
enough for the arms to be effective at clearing the obstruction.
Thus, the short working distance between the pilot area and the
underreaming arms in the bits of the present disclosure may allow
the disclosed underreamer devices to be used in such a
situation.
[0033] In other embodiments, a further advantage of the disclosed
underreaming bits and assemblies is that many of the components are
replaceable and/or interchangeable. Thus, when components of the
assembly become worn, they may be replaced with new components
without having to replace the whole bit or bit assembly. For
instance, the buttons on the arms or pilot face may be replaced, as
may the outer body, and the individual arms. Furthermore, in some
embodiments, the center shaft may be exchanged with a different
center shaft, and/or a different outer body may be substituted,
allowing the device to be configured to suit the specific
conditions of the task at hand.
[0034] Additionally, the design of the bit assembly and center
shaft may result in a highly efficient torque transfer through the
center shaft. This may increase the efficiency of the system, and
may increase the boring and underreaming efficacy of the device as
compared to conventional devices.
[0035] FIG. 1 shows an exemplary underreaming device 10 with the
arms 70 in an extended position, and FIG. 2 illustrates the
embodiment shown in FIG. 1 with the arms 70 in a retracted
position. FIG. 3 illustrates an exploded view of the underreamer
assembly shown in FIG. 1, and FIG. 4 illustrates a side view of the
exemplary center shaft shown in FIG. 1, in accordance with various
embodiments. FIG. 5 illustrates a cross-sectional view of a center
shaft, in accordance with various embodiments. FIG. 6 illustrates a
perspective view of a center shaft, in accordance with various
embodiments.
[0036] Referring to FIG. 1, in general, the underreaming device 10
may include a drive device coupler 20, which, in some embodiments,
may couple the underreaming device to a drive device, and which may
form a part of and communicate rotational torque, impact, vibration
and/or linear force to the center actuating shaft 30, which may in
turn transfer rotational torque, impact, and/or vibration to the
bit body 50 and/or to one or more arms 70. In some embodiments,
such as the illustrated embodiment, two arms 70 are used. However,
any number of arms may be used, depending on the particular
excavation conditions, the size of the arms, and the diameter of
the bit body 50 being used. For instance, in various embodiments,
underreaming device 10 may have one, two, three, four, five, six,
seven, or even more arms, depending on the intended use, the
diameter of bit body 50, the diameter of the hole being excavated,
or the substrate in which underreaming device 10 is used. In some
embodiments, bit body 50 may be configured to have a size
appropriate for passing inside a standard steel pipe or casing.
[0037] In various embodiments, bit body 50 may transfer torque to
and/or serve as a guide for arms 70. In use, in various
embodiments, arms 70 may travel from the extended position shown in
FIG. 1 to the retracted position illustrated in FIG. 2 and back
again repeatedly in order to effect an underreaming function. FIG.
3 illustrates the relationship between arms 70 and bit body 50, and
in particular, how they rest in apertures formed by perpendicular
surfaces 60 and primary arm pocket surfaces 61 in bit body 50. In
some embodiments, bit body 50 may rotate in a clockwise or
counterclockwise direction (or alternate directions) during use,
and may advance in an axial (e.g., distal) direction as the hole is
excavated.
[0038] Referring to FIG. 4, which shows center actuating shaft 30
in side view, and FIG. 5, which shows center actuating shaft 30 in
cross section, center actuating shaft 30 may have a central hole 22
for air, water, or any other flush media to pass though. Center
actuating shaft 30 may also have a main section 32 having a
specified diameter, and an adjacent (e.g., approximately 90 degree)
face that fits within bit body 50, according to various
embodiments. Center actuating shaft 30 may, in some embodiments,
guide bit body 50 and transfer impact to the adjacent face (e.g.,
top or proximal edge) of bit body 50. Center actuating shaft 30
also may have an undercut section 34 having a specified diameter
with two adjacent (e.g., approximately 90 degree) faces. In one
embodiment, undercut section 34 may have a specified diameter, and
may have a size sufficient to allow a spring retainer (not shown)
to be collapsed for assembly and disassembly, and to be positioned
to keep arm 70 engaged in the retracted position. Although in the
illustrated embodiment, the spring retainer functions to couple bit
body 50 to center actuating shaft 30, any other retention device
may be used for this purpose, as will be appreciated by those of
skill in the art.
[0039] In various embodiments, center actuating shaft 30 also may
have air holes 36 that communicate with the main central hole 22.
Air holes 36 may be used for cleaning debris from the mechanism,
according to various embodiments. Embodiments of center actuating
shaft 30 also may have an extended step surface 38 with adjacent
sides parallel to center actuating shaft 30. A ramp angle surface
40 may serve as a transfer between the extended step surface 38 and
a retract step surface 42, which may have adjacent sides that are
substantially parallel to the shaft. According to various
embodiments, ramp angle surface 40 may have one or more air holes
44 that communicate with central hole 22. In embodiments, air holes
44 may be used for clearing debris or other media from the bit
assembly. In addition, center actuation shaft 30 may have a radial
air groove 46. Some embodiments may provide a face 48 perpendicular
to center actuating shaft 30, and in some embodiments face 48 may
include one or more carbide (or other rock cutting material)
compact buttons or inserts 90.
[0040] FIGS. 7A, 7B, and 7C illustrate a side view of a bit body
(FIG. 7A), a side view of a spring retainer (FIG. 7B) and cross
sectional view of a bit body (FIG. 7C), in accordance with various
embodiments. Referring to FIGS. 7A-7C, bit body 50 may have a main
diameter bore 52 with an adjacent face that may guide bit body 50
on center shaft 30 and may transfer impact force through the
adjacent face to the face of center actuating shaft 30. Also
included in some embodiments is a radial groove 54 that has two
adjacent faces that fit a spring retainer and/or spring retainer
ring 55. In some embodiments, holes 56 run perpendicularly through
bit body 50 and center actuation shaft 30. In use, keys, pins, or
other elongated objects may be inserted through holes 56 to
collapse spring retainer ring 55 and uncouple bit body 50 from
center actuating shaft 30. Thus, bit body 50 may be easily
uncoupled from center actuating shaft 30, for instance when bit
body 50 requires replacing due to wear, when a different diameter
bit body 50 is desired, or when arms 70 need to be accessed or
replaced.
[0041] In various embodiments is a radial pocket surface 58 that
may act as a stop to prevent over extension of the arms 70 in the
extended position. In some embodiments, perpendicular surfaces 60
are included and disposed to mate with arms 70. Additional surfaces
may include primary arm pocket surfaces 61 and secondary arm
surfaces 62, both of which may be generally perpendicular to center
actuation shaft 30. Some embodiments may also include a radial
angle surface 63 that may include compact inserts 90. Additionally,
bit body 50 may include one or more face flushing slots 64 running
perpendicular to center actuating shaft 30, and main return
flushing slots 66 parallel to center actuating shaft 30 that may
intersect with one or more face flushing slots 64. Some embodiments
also may include a face 68 generally perpendicular to center
actuating shaft 30 that may have additional carbide (or other
cutting material) compact buttons or inserts 90 coupled
thereto.
[0042] FIG. 8 illustrates a perspective view of an example of bit
body 50, in accordance with various embodiments, and FIGS. 9A, 9B,
and 9C illustrate a perspective view (FIG. 9A), side view (FIG.
9B), and back view (FIG. 9C) of an example of arm 70, in accordance
with various embodiments. Referring to FIG. 9, arm 70 may be a
removable and replaceable component that has a radial diameter
surface 72 that may define a ream diameter, and a radial plot
surface 74 having a specified diameter. Also included in some
embodiments is a radial angle surface 76 that has inserts 90
coupled thereto. A perpendicular face 78 also may have compact
inserts 90, and may act as part of the pilot surface in some
embodiments. Another perpendicular surface 80 may be configured to
contact and mate with the bit body arm pocket 60. Also included in
some embodiments is a plurality of major arm surfaces 81 that may
contact and mate with the major arm pocket surfaces 61. Also
contemplated are minor arm surfaces 82 that may contact and mate
with minor arm surfaces 62.
[0043] Some embodiments may include one or more radial stop
surfaces 84, which may contact and mate with bit body radial pocket
surface 58. Further embodiments also may include a radial back
angle surface 86 for aiding in the retractions of radial arms 70. A
parallel actuating surface 88 may contact and mate with center
actuating shaft 30 during operation, and in some embodiments it may
contact and mate with retract step surface 42, the ramp angle
surface 40, and/or extended step surface 38. Embedded in the
surface may be buttons or compact inserts 90, according to various
embodiments.
[0044] FIG. 10 illustrates a cross-sectional view of an example of
center actuating shaft 30 with the air or media flow pathway
indicated, in accordance with various embodiments, and FIG. 11
illustrates a face view of the underreamer assembly 10 with arms 70
in the extended position, in accordance with various
embodiments.
[0045] In operation, in various embodiments, drive device coupler
20 (which in some embodiments may be an integral part of center
actuating shaft 30) may be the adapter to which a down hole hammer,
drill rod for hydraulic hammer, or any other means to impart
rotational torque, impact energy, vibration, or linear feed force
may be used to move (for instance rotate or advance) center shaft
30. In various embodiments, center actuating shaft 30 (and thus
coupler 20) may be interchanged with other shafts/couplers in order
to change the assembly to be, for instance, mated with a down hole
hammer or a drill rod for a hydraulic hammer.
[0046] In some embodiments, the rotational torque from center
actuating shaft 30 may be imparted to arms 70 by means of contact
with surfaces 42, 44, and 38. The rotational torque may then be
transferred from arms 70 into bit body 50 in some embodiments by
means of contact with surfaces 81 and 82 of arms 70 and their mated
surfaces 61 and 62 bit body 50.
[0047] FIG. 15 illustrates a side view of an alternate embodiment
of the underreamer assembly configured to be driven by a hex drive
mechanism; and FIGS. 16A, 16B, 16C, and 16D illustrate a side view
of an embodiments of a bit body (FIG. 16A), a side view of a spring
retainer (FIG. 16B), a cross sectional view of a bit body (FIG.
16C), and a transverse cross sectional view of a bit assembly (FIG.
16D), all components of a bit assembly configured for use with a
hex drive mechanism, in accordance with various embodiments. In
these embodiments, instead of imparting torque directly to arms 70,
which then impart torque to bit body 50, rotational torque from
center actuating shaft 30 may be imparted to bit body 50 via drive
members 31, 51. Although a hex drive interface is illustrated, any
torque transfer interface may be substituted, for instance a spline
drive mechanism or any interface having any number of flat
surfaces, facets, recesses in, or projections from center shaft 30
that are configured to mate with and/or engage corresponding
features in bit body 50. In various embodiments, use of the
hex/spline drive mechanism (for instance, drive members 31, 51) may
help to avoid excessive loading and wear on surfaces 38. 40, and 42
on center actuating shaft 30, and mated surfaces 61 and 62 on bit
body 50, while maintaining alignment of the components and ensuring
smooth operation of arm 70 deployment and retraction. Thus, the
illustrated hex drive mechanism may help avoid causing excessive
wear and tear on arms 70 and bit body 50.
[0048] Whereas FIGS. 15 and 16 illustrate an example of a center
shaft 30/bit body 50 drive members 31, 51 being located proximal to
spring retainer 55, one of skill in the art will appreciate that
such drive members 31, 51 may alternately or additionally be
located distal to spring retainer 55, as shown in FIGS. 17 and 18.
FIG. 17 illustrates a side view of another alternate embodiment of
the underreamer assembly configured to be driven by a hex drive
mechanism, in accordance with various embodiments; and FIG. 18
illustrates a cross sectional view of components of a bit assembly
configured for use with a hex drive mechanism, in accordance with
various embodiments. In some embodiments, such as the embodiment
illustrated in FIGS. 17 and 18, a hex drive, spline drive, or other
drive member 31, 51 may be located at any point between the distal
tip of center shaft 30 and spring retainer 55. In some embodiments,
positioning drive members 31, 51 distal to (e.g., below) spring
retainer 55 may increase the area of contact between opposing drive
members 31, 51, which may reduce wear and may decrease the height
of bit body 50 in some embodiments.
[0049] In some embodiments, arms 70 may be deployed by the linear
(e.g. axial) force applied to center actuating shaft 30 and
transferred to bit body 50. As bit body 50 moves, arms 70 may be
engaged by means of contact with surfaces 88, 42, 44, and 38. At
the point of full deployment, arms 70 may be kept from deploying
further by means of surfaces 84 and 58, which collectively may be
referred to as the "stop pocket." Impact energy may be imparted
from center actuating shaft 30 by means of surface 32 and its
adjacent surface 42 in bit body 50, and into arms 70 by means of
surfaces 60 and 80, in accordance with various embodiments.
[0050] FIG. 12 illustrates a perspective view of the assembly of
various interchangeable components. As described above, one
advantage of the disclosed underreaming bits and assemblies is that
many of the components are replaceable and/or interchangeable.
Thus, when components of the assembly become worn, they may be
replaced with new components without having to replace the whole
bit or bit assembly. For instance, the buttons on the arms or pilot
face may be replaced, as may bit body 50, and individual arms 70.
Furthermore, in some embodiments, center shaft 30 may be exchanged
with a different center shaft, and/or a different bit body 50 may
be substituted, allowing worn components to be replaced, and/or the
device to be configured to suit the specific conditions of the task
at hand.
[0051] As described above, in use, retention device 55 may be
collapsed or otherwise disengaged, for instance by inserting keys,
pins, or other elongated objects through holes 56, thus uncoupling
bit body 50 from center actuating shaft 30. Once bit body 50 has
been removed from center actuating shaft 30, arms 70 may be removed
from the interior of bit body 50 by retracting them into bit body
50 and lifting them out of the recesses in which they rest.
Replacement arms may then be inserted into bit body 50 if desired,
and/or a replacement bit body 50 may be coupled to center shaft 30,
for instance one having a larger or smaller diameter, a different
number of arms, or other desirable features, such as a different
drive mechanism.
[0052] FIG. 13 illustrates a perspective view of the flow of air,
water, and/or flush media through an exemplary underreamer
assembly; and FIG. 14 illustrates a cross-sectional view of the
flow of air, water, and/or flush media through an exemplary
underreamer assembly; all in accordance with various embodiments.
As illustrated in in FIGS. 13 and 14, in various embodiments,
substantially all of the air, water, and/or flush media may pass
through the underreamer assembly and exit through the distal
cutting face in a downward direction, substantially parallel to the
longitudinal axis of the device and perpendicular to the distal
cutting face. In various embodiments, such downward airflow may
direct substantially all of the air, water, and/or flush media away
from the side (lateral) walls of the bore hole, thus preventing
over excavation when loose strata are encountered during a boring
operation. In particular embodiments, unlike conventional
underreamers, essentially no flush media pass laterally against the
sides of the bore hole, as any air, water, and/or flush media
traveling laterally towards the bore hole walls will be diverted by
arms 70 and/or the outer edge of bit body 50, particularly when
arms 70 are in the extended position. Thus, in various embodiments,
at least 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98% or
99% of the air, water, and/or flush media may be directed away and
along the central axis and perpendicular to the distal cutting
face. Similarly, in some embodiments, less than 20%, 15%, 10%, 9%,
8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% of the air, water, and/or flush
media may be directed laterally towards the side wall of the bore
hole. Thus, the device may avoid the over-excavation problems
associated with conventional underreamers.
[0053] Debris removal may be accomplished in some embodiments by
flush media of air, water, or any combination of fluid or gas,
through central hole 22, into air holes 44, and deflected by
surface 88 of arms 70. Following that, the flush media may move
around center actuating shaft 30 and radial air groove 46 in some
embodiments, e.g., to exit the assembly in a direction parallel to
the drilled hole, without impacting the sides of the hole. The
media may then be returned via face flushing slot 64 into return
flushing slot 66 in some embodiments. A small amount of flush media
may be diverted to holes 36 to keep the mechanism clean of debris
in certain embodiments.
[0054] Although certain embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that a wide variety of alternate and/or equivalent
embodiments or implementations calculated to achieve the same
purposes may be substituted for the embodiments shown and described
without departing from the scope. Those with skill in the art will
readily appreciate that embodiments may be implemented in a very
wide variety of ways. This application is intended to cover any
adaptations or variations of the embodiments discussed herein.
Therefore, it is manifestly intended that embodiments be limited
only by the claims and the equivalents thereof.
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