Note: Descriptions are shown in the official language in which they were submitted.
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GOUGING CUTTER STRUCTURE AND DRILL BIT MADE
THEREWITH
Background
[0001] This disclosure relates generally to the field of rotary drill
bits. More specifically,
the disclosure relates to drill bits having "gouging" type cutters and
structures for such
cutters.
[0002] Fixed cutter bits known in the art include polycrystalline diamond
compact
("PDC") bits, wherein a plurality of PDC cutters are affixed to a bit body in
a selected
arrangement on one or more blades formed in the bit body.
[0003] Gouging type cutters are used in drill bits for drilling mine
shafts or tunnels,
among other uses. Such bits are known in the art as "claw" bits, one example
of which is
sold under the trademark QUI-KLAW, which is a trademark of Drillhead, Inc.
Such bits
are known to be useful in drilling clay, unconsolidated sand, loose rock and
gravel.
[0004] U.S. Patent No. 8,505,634 issued to Lyons et al. describes a drill
bit having
gouging cutting elements disposed adjacent to shearing cutting elements on a
blade on
the bit body. The shearing cutting elements have a planar cutting face, while
the gouging
cutting elements have a non-planar cutting face, e.g., dome shaped or cone
shaped.
Brief Description of the Drawings
[0005] FIG. 1 is an oblique view on an example drill bit according to the
present
disclosure.
[0006] FIG. 2 shows a side view of an example blade of the bit shown in
FIG. 1.
[0007] FIG. 3 shows one example of a shear cutter.
[0008] FIG. 4A shows an exploded view of one example of a gouging cutter.
[0009] FIG. 4B shows the example gouging cutter as fully assembled.
[0010] FIG. 4C shows another example embodiment of a gouging cutter.
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[00111 FIG. 4D shows an assembled view of another embodiment of a gouging
cutter.
[0012] FIG. 4E shows an exploded view of the embodiment shown in FIG. 4D.
[0013] FIG. 4F shows another embodiment of a gouging cutter.
[0014] FIG. 4G shows an exploded view of another example embodiment of a
gouging
cutter.
[0015] FIG. 5 shows another example of a drill bit according to the
present disclosure.
[0016] FIG. 6 shows an oblique view of blades according to the example bit
shown in
FIG. 5.
[0017] FIG. 7 shows an example blade having shear cutters with gouging
cutters
disposed rotationally ahead of the shear cutters.
[0018] FIG. 8 shows an example blade having gouging cutters disposed
rotationally
behind gouging cutters.
Detailed Description
[0019] An example drill bit according to the present disclosure is shown
in oblique view
at 10 in FIG. 1. The bit 10 may include a bit body 11 having a tool joint
section 11A for
coupling the bit body 11 to a drill string (not shown) and a cutting section
11B which
may include a plurality of circumferentially spaced apart blades 12. The bit
body 11 may
be formed from steel and have an abrasion resistant coating such as tungsten
carbide
applied to certain wear susceptible areas (not shown) on the bit body 11. The
bit body
may also be made, for example, from carbide matrix of compositions known in
the art.
Each of the blades 12, in some embodiments, may extend from a selected
distance
proximate the axial center of the bit body 11, radially outwardly to a gage
portion 13
having a diameter approximately equal to the diameter of a wellbore to be
drilled by the
bit 10. The gage portion 13 of each blade 12 may include gage cutters 14 made,
for
example, from a hard or superhard material such as polycrystalline diamond,
cubic boron
nitride, diamond impregnated tungsten carbide or tungsten carbide. The present
example
includes six, circumferentially equally spaced apart blades 12, but the number
of blades
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and the circumferential spacing therebetween are not limits on the scope of
the present
disclosure.
[0020] At least one or each blade 12 may define a stepped, dual "profile"
or curved
shape. In the present example, a forward (with respect to direction of
rotation of the bit)
step of at least one or all of the blades 12 may be longitudinally lower or
behind (further
back or rearward with respect to the direction the bit will drill) than a
rearward step of
blade 12, as will be further explained below with reference to FIG. 2. Lower
in the
present context means further from the drilling surface defined by the profile
of the
blades 12. The forward step of the profile may include a plurality of pick
type or gouging
cutters 18 spaced in a row along the forward step. The gouging type cutters 18
will be
further explained below. The rearward step of the profile may in some examples
include
a plurality of shear cutters 16, such as, for example, polycrystalline diamond
compact
(PDC) cutters, tungsten carbide cutters, or cubic boron nitride cutters of any
type known
in the art. The foregoing arrangement of blades and cutters is only meant to
service as an
example of a drill bit made with gouging cutters according to the present
disclosure and
is not intended to limit the scope of the present disclosure.
[0021] The shear cutters 16 may be mounted on the blade 12 at a selected
backrake
angle. The gouging cutters 18 may be mounted in openings (18A in FIG. 2) at a
selected
forward rake angle. In some examples, the tips (FIG. 4) of the gouging cutters
18 may
extend longitudinally ahead of (in the direction the bit will drill) a cutting
surface defined
by the shear cutters 16 by about 0.5 inches (13 mm). The foregoing dimensions
are only
an example, and are not intended to limit the scope of the present disclosure.
[0022] A space between circumferentially adjacent blades 12 may foun a
flow path or
waterway to enable space for cuttings generated by the bit 10 to be disposed
until they are
forced out by the action of drilling fluid pumped through one or more nozzles
or "jets" 20
inserted into the bit body 11 as shown in FIG. 1.
[0023] FIG. 2 shows a side view of one of the blades 12 without the
cutters (16, 18 in
FIG. 1) to better illustrate some of the blade's features. The blade 12 in the
present
example may define a forward (with respect to direction of rotation of the
bit) step 22 that
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traverses a curved profile. The forward step 22 may extend radially inwardly
to a
predetermined position (i.e., a selected distance from the center of rotation
of the bit
body) enabling convenience of placement of the gouging cutters (18 in FIG. 1)
in
substantially cylindrically shaped pockets 18A. The curvature of the profile
may
substantially match the curvature of a corresponding portion of a rearward
step 24 on the
blade 12, or may have a different curvature. The rearward step 24 may be
elevated (or
extended longitudinally in the direction of drilling) by a selected distance H
at one or
more lateral positions along the blade 12. In the present example, the
distance H may be
about 0.5 inches (13 mm). As previously explained, such dimension and step
type blade
structure are not limits on the scope of the present disclosure, but are meant
only to
illustrate and example structure for a drill bit using gouging cutters as will
be further
explained below with reference to FIGS. 4A and 4B. The rearward step 24 (if
such blade
structure is used) may define a profile that extends radially outward to the
gage surface
13 and may extend radially inward to a selected distance from the axis of
rotation of the
bit body (11 in FIG. 1) somewhat more or somewhat less than the forward step
22. The
rearward step 24 shown in FIG. 2 may in some examples include pockets 16A for
mounting the shear cutters (16 in FIG. 1). The curvature of the profile
defined by the
rearward step 24 may be any profile known to be used with fixed shear cutter
drill bits.
The distance by which the tips of the gouging cutters (18 in FIG. 1) extend
beyond the
rearward step 24 or a cutting surface defined by the shear cutters (16 in FIG.
1), if used,
will be related to the length of the gouging cutters (18 in FIG. 1) and the
selected distance
H. However, it should be clearly understood that other embodiments of a drill
bit made
using gouging cutters according to the present disclosure may use blade
profiles suitable
for use of only gouging type cutters. It is also within the scope of the
present disclosure
to use gouging cutters as will be explained below on one or more roller cones
of a roller
cone type drill bit.
[0024]
In other examples, the rearward step 24 or any or all of the blades 12 may
omit
the mounting pockets 16A and the shear cutters (16 in FIG. 1). In some
examples, the
blades (12 in FIG. 1) may only include a single profile surface that extends a
selected
distance from the rotational axis of the bit to the gage surface (13 in FIG.
1) and the
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gouging cutters (18 in FIG. 1) are mounted to the bit body (11 in FIG. 1) so
that the tips
thereof are disposed at a selected longitudinal distance ahead of the blade
profile surface.
[0025] An example shear cutter 16 is shown in side view in FIG. 3. The
example shown
in FIG. 3 is a PDC cutter, although other types of shear cutters may be used
in other
implementations of a bit according to the disclosure. The shear cutter 16 may
include a
substrate 30 such as may be made from tungsten carbide or other material known
in the
art for such use in PDC cutters. A diamond table 32 may be affixed to an upper
surface
of the substrate 30. The diamond table 32 may be made from polycrystalline
diamond
using processes known in the art. Any known configuration of interface between
the
diamond table 32 and the substrate 30 may be used. The diamond table may have
an
exposed substantially planar surface 32A, which may have a chamfer 32B at its
edge.
The substrate 30 may be brazed to the bit body (11 in FIG. 1) on one of the
pockets (16A
in FIG. 2) using techniques known in the art. In other examples, the shear
cutters 16 may
be made from materials such as tungsten carbide, diamond impregnated tungsten
carbide
or cubic boron nitride. The shape of the shear cutters is not intended to
limit the scope of
the present disclosure.
[0026] FIG. 4A shows an exploded view of one of the gouging cutters 18
according to
the present disclosure as it would be mounted in one of the pockets (18A in a
blade 12 in
FIG. 2). The gouging cutter 18 may include a substantially circular cross
section cutter
mount body 18D made from steel or similar high strength metal. The cutter
mount body
18D may also be made from materials such as sintered tungsten carbide. The
cutter
mount body 18D may be brazed to the bit body (11 in FIG. 1) in a respective
one of the
pockets (18A in FIG. 2) or may be interference fit therein so that the cutter
mount body
18D is retained in the bit body. In some embodiments the cutter mount body 18D
is
inserted into the pocket (18A in FIG. 2). In some embodiments, the gouging
cutter 18
may be removed from the respective pocket 18A for servicing or replacement..
The
manner of mounting the cutter mount body 18D in the pocket (18A in FIG. 2) is
not
intended to limit the scope of the present disclosure.
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[0027] The present embodiment, and additional example embodiments to be
described in
more detail below enable the cutter mount body 18D to be affixed to the bit
body, while
enabling replacement of a gouging cutting element. The gouging cutting element
may be
mounted within the cutter mount body 18D or to the cutter mount body 18D so
that it is
free to rotate with respect to the cutter mount body 18D.
[0028] A gouging cutting element 18B may be made from, for example,
tungsten
carbine, cubic boron nitride, polycrystalline diamond or any other material
known in the
art for making a gouging cutter cutting surface. The gouging cutting element
18B may be
substantially round in cross section. In the present example embodiment, a
main diameter
portion 318 may have a diameter selected to be smaller than an internal
diameter of the
cutter mount body 18D. An outer end 118 of the cutting element 18B may be
shaped
substantially conically as shown in FIG. 4A, but may have any other shape
known in the
art for gouging type cutters. An inner end 218 of the cutting element 18B may
have a
substantially round cross section and a diameter selected to substantially
match the
interior diameter of the gouging cutter mount body 18D. A retainer 18C may
have an
interior opening 418 having an internal diameter selected to enable free
passage of the
main diameter portion 318 of the cutting element 18B therethrough, and a
mounting
surface 518 having an outer diameter selected to fit within the interior
diameter of the
gouging cutter mount body 18D. The retainer 18C may be affixed to the gouging
cutter
mount body, for example, by threading, welding, brazing, using a snap ring or
any other
mounting device known in the art.
[0029] When the retainer 18C is affixed to the gouging cutter mount body
18D, the
cutting element 18B may be retained in place within the gouging cutter mount
body 18D
while free to rotate with respect thereto. If the cutting element 18B should
be worn or
damaged during use of a drill bit using such gouging cutters 18, it may be
possible to
replace only the cutting element 18B in the present example embodiment by
removing
the retainer 18C. Thus, in some examples, the gouging cutter mount body 18D
may be
permanently or semi permanently affixed to the bit body (11 in FIG. 1). The
relative
diameters of the main portion 318, the interior diameter of the cutter mount
body 18D
and the opening 418 in the retainer 18C may be selected so that the cutting
element 18B
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may rotate freely in the cutting element body 18D. In other embodiments, the
cutting
element body 18D may be mounted in the pocket (18A in FIG. 2) so that it may
freely
rotate. Such mounting may include, for example, snap rings or the like. It
will be
appreciated by those skilled in the art that a length of the main diameter
portion may be
selected so that the outer end 118 of the cutting element protrudes through
the opening
418 in the retainer 18C.
[0030] FIG. 4B shows the gouging cutter 18 fully assembled as it would be
affixed in a
corresponding pocket (18A in FIG. 2) in the bit body (11 in FIG. 1).
[0031] Embodiments to be described below with reference to FIGS. 4C
through 4F may
provide means for releasably mounting a gouging cutting element to a gouging
cutter
mount body, wherein the gouging cutting element may rotate freely with respect
to the
cutter mount body. The following embodiments may include an opening formed on
a
longitudinal end of the cutting element (which may or may not include a
separate rotating
cutter body), wherein a groove is formed on an interior surface of the
opening. The cutter
mount body may have a feature which mates with the opening. An exterior
surface of the
feature on the cutter mount body may include a corresponding groove that
cooperates
with the groove on the interior surface of the opening when a locking element
is disposed
in both grooves. In some embodiments, the locking element may comprise ball
bearings
or locking balls. In some embodiments, the locking element may comprise a snap
ring.
In some embodiments, the locking feature may comprise a set screw.
[0032] FIG. 4C shows a cross section of another example embodiment of a
gouging
cutter 220. The example shown in FIG. 4C is assembled. A gouging cutting
element
118A may be brazed or interference fit, for example, into a gouging cutting
element
rotating body 118B. The gouging cutting element 118A may be made from
materials as
explained with reference to the previously described embodiment and may be
similarly
shaped at a cutting surface end thereof. The gouging cutting element rotating
body 118B
may be made from steel or sintered tungsten carbide, as non-limiting examples.
The
assembled gouging cutting element 118A and gouging cutting element rotating
body
118B may be rotatably mounted to another embodiment of a gouging cutter mount
body
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18D. The present embodiment of the gouging cutter mount body 18D may be
substantially cylindrically shaped and include a reduced diameter portion
having a ball
retaining groove therein. Retaining balls 118D, which may be made from steel
or other
high strength material may be urged into the groove and also be urged into a
corresponding retaining groove 118G formed in a portion (e.g., an opening such
as a
cylindrical opening) as shown in the cutting element rotating body 118B. A
retaining
sleeve 118C may be disposed radially externally to the retaining balls 118D,
the gouging
cutter mount body 18D and the gouging cutting element rotating body 118B so
that the
retaining balls retain the gouging cutting element rotating body 118B to the
gouging
cutter mount body 18D while enabling free relative rotation therebetween. A
spring 118F
or similar biasing device may hold the retaining sleeve 118C in the position
shown in
FIG. 4C. To enable removal of the gouging element rotating body 118B from the
cutter
mount body 18D, the retaining sleeve 118C may be urged downwardly against the
basing
force of the spring 118F so that the retaining balls 118D are enabled to move
into a
release groove 118E on the interior surface of the retaining sleeve 118C. The
gouging
cutting element rotating body may them be removed by pulling it away from the
gouging
cutter mount body 18C axially. A replacement assembly including a gouging
cutting
element 118A and gouging cutting element holding fixture 118B may be inserted
into the
retaining sleeve 118C, and the retaining sleeve 118C may be subsequently
released.
Thus, the replacement assembled gouging cutting element and gouging cutting
element
holding fixture may be locked to the gouging cutter mount body 18D while
enabled to
rotate freely with respect thereto. In the present embodiment, it may thus be
possible to
replace the gouging cutting element 118A without removing the cutter mount
body 18D
from the bit body (11 in FIG. 1).
[0033]
FIG. 4D shows another example embodiment of a gouging cutter 222. The
present embodiment may include a gouging cutting element 118A and a gouging
cutting
element holding fixture 118B substantially as in the embodiment described with
reference to FIG. 4C. In the present embodiment, a snap ring retaining groove
222B may
be founed on an inner surface of a cylindrical bore in the gouging cutting
element
holding fixture 118B. A corresponding snap ring groove 222C may be foi _____
ined on an
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exterior surface of a reduced diameter portion of the gouging cutter mount
body 18C. A
snap ring 222A maybe inserted into the groove 222B prior to assembly of the
gouging
cutting element holding fixture 118B to the gouging cutter mount body 18D.
When
assembled, the snap ring 222A retains the gouging cutting element holding
fixture 118B
to the cutter mount body 18D while enbling free relative rotation
therebetween. A
release provision, such as a hole or other opening (not shown) through the
gouging
cutting element holding fixture 118B may enable use of a pin or similar
release tool to
compress the snap ring 222A to enable release of the gouging cutting element
holding
fixture 118B from the cutter mount body 18D to enable replacement of the
former (with
its assembled gouging cutting element 118A). An exploded view of the
embodiment of
FIG. 4D is shown in FIG. 4E. In the present embodiment, it is also possible to
release /
remove gouging cutting element holding fixture 118B simply by pulling on it
with a tool
such as a slide hammer. The groove on the outer surface of the gouging cutting
element
holding fixture 118B may be configured for a tool that slides into the groove
and attaches
to the end of the slide hammer.
[0034]
FIG. 4F shows an cross section of another embodiment of a gouging cutter fully
assembled. In the present embodiment, a gouging cutter 118A and gouging cutter
holding fixture 118B may be formed and assembled as explained with reference
to the
embodiments described with reference to FIGS. 4C and 4D. In the present
embodiment,
an interior surface of a cylindrical opening in the bottom of the gouging
cutting element
holding fixture 118B may include a retaining groove 118J formed therein. A
radius of
the retaining groove 118J may be selected to enable close tolerance, yet free
rolling fit of
a plurality of ball bearings 11811 therein. A mating cylindrical post on the
cutter mount
body 18D may include a similar retaining groove 118K on its exterior surface.
When the
gouging cutting element holding fixture 118B is positioned on the cutter mount
body
18D, ball bearings 11811 may be inserted into a toroidal opening created by
positioning
the respective grooves 118J, 118K as shown in FIG. 4F. After the toroidal
opening is
substantially filled with ball bearings 11811 through a fill port 118M in the
gouging cutter
holding fixture 118B, the fill port 118M may be sealed with a plug 118L. The
plug 118L
may be brazed or interference fit into the fill port 118M. Replacement of the
gouging
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cutter 118A may be performed by removing the plug 118L and removing the ball
bearings 118H through the fill port 118M, thus releasing the gouging cutter
rotating body
118B from the cutter mount body 18D. Replacement may be performed similarly to
the
original assembly procedure explained above.
[0035] FIG. 4G shows an exploded view of another example embodiment of a
gouging
cutter. The present example gouging cutter 226 may include a gouging cutting
element
118A affixed to a rotating cutter body 118B as in the previous embodiments. A
cutter
mount body 18D may include a groove 118K on an exterior surface thereof as
shown. A
set screw 118L may be inserted through an opening 118M in the rotating cutter
body
118B such that when fully inserted therein, an end of the set screw 118L is
disposed in
the groove 118K, thus rotatably locking the rotating cutter body 118B to the
cutter
mounting body 18D.
[0036] The foregoing example embodiments of a gouging cutter for a drill
bit have in
common that the gouging cutter is replaceably mounted to a cutter mount body,
such that
the gouging cutter may freely rotate with respect to the cutter mount body.
While the
embodiments shown in FIGS. 4C, 4D, 4E and 4F include a separate cutting
element and
rotating cutter body, other embodiments may have the cutting element and
rotating cutter
body formed integrally as a single component.
[0037] Referring again to FIG. 4F, in some embodiments an aspect ratio of
the gouging
cutter may be limited. The aspect ratio in the present context means the ratio
of the
overall length of the gouging cutter, shown at L with respect to its overall
diameter,
shown at D. In some embodiments, the aspect ratio may be at most 2.5. The same
limitation on the aspect ratio may be applied to any of the other embodiments
shown in
and explained with reference to FIGS. 4A, 4B, 4C, 4D, 4E and 4G. Limiting the
aspect
ratio may reduce breakage of the gouging cutter during use.
[0038] It should also be clearly understood that while the example cutter
mount bodies
shown in and described with reference to FIGS. 4A through 4E are affixable to
a bit
body, they may also be integrally formed with the bit body while including
features to
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enable replaceable retention of the cutting element while allowing free
rotation of the
cutting element with respect to the cutter mount body.
[0039] FIG. 5 shows another example of a drill bit according to the
present disclosure in
which the gouging cutters 18 are mounted to the bit body 11 so as to be
disposed
rotationally behind the shear cutters 16. In the example of FIG. 5, the tips
of the gouging
cutters 18 may extend a selected distance beyond a cutting surface defined by
the shear
cutters 16.
[0040] FIG. 6 shows an enlarged view of the bit body of FIG. 5 wherein
pockets 16A for
the shear cutters (16 in FIG. 5) are disposed at locations along the blade 12,
and the
pockets 18A for the gouging cutters (18 in FIG. 5 are shown disposed
rotationally behind
the blade 12. In the example of FIG. 6, the tips of the gouging cutters (18 in
FIG. 5) may
extend a selected longitudinal distance ahead of the cutting surface defined
by the shear
cutters (16 in FIG. 5) when mounted in the pockets 18A.
[0041] FIG. 7 shows another example wherein the blade 12 only comprises
mounting for
the shear cutters 16. The gouging cutters 18 may be mounted rotationally ahead
of the
shear cutters 16 in pockets that are not on the blade top. In the example of
FIG. 7, the
tips of the gouging cutters 18 may extend a selected longitudinal distance
ahead of the
cutting surface defined by the shear cutters 16.
[0042] FIG. 8 shows another example wherein at least one of the blades 12
includes
gouging cutters 18 mounted therein and shear cutters 16 mounted on the blade
12
rotationally ahead of the gouging cutters 18. The tips of the gouging cutters
18 may
extend a selected distance longitudinally ahead of a cutting surface defined
by the shear
cutters 16.
[0043] In other examples, gouging cutters may be mounted on one or more
blades and
shear cutters may be mounted on one or more blades. In such examples, as in
the other
examples described above, the gouging cutters and shear cutters may be affixed
to the
blades within the stated respective ranges of rake angles, and the gouging
cutters may
extend longitudinally ahead of the cutting surface defined by the shear
cutters by the
distances described above.
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[0044] In the examples of FIGS. 5 through 8, the gouging cutters and shear
cutters may
have rake angles, structures and compositions substantially as set forth with
reference to
the examples described with reference to FIGS. 1 through 3. It should be
clearly
understood that the examples described herein including both gouging type
cutters and
shear cutters is not a limitation on the scope of the present disclosure.
Other
embodiments may use only gouging type cutters made as explained with reference
to
FIGS. 4D and 4E.
[0045] Drill bits made according to the present disclosure may have
gouging cutters that
may be more readily serviceable than gouging type cutters known in the art.
Other
possible benefits of a drill bit made according to the present disclosure may
include that a
rotatable gouging cutter is much more robust (less prone to loss or breakage)
and can be
much made smaller than gouging cutters known in the art prior to the present
disclosure.
[0046] While the invention has been described with respect to a limited
number of
embodiments, those skilled in the art, having benefit of this disclosure, will
appreciate
that other embodiments can be devised which do not depart from the scope of
the
invention as disclosed herein. Accordingly, the scope of the invention should
be limited
only by the attached claims.
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