U.S. patent application number 09/682193 was filed with the patent office on 2002-02-21 for multi-directional cutters for drillout bi-center drill bits.
Invention is credited to Daly, Jeffery E., Hart, Steven James, Watson, Graham R..
Application Number | 20020020565 09/682193 |
Document ID | / |
Family ID | 22851532 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020020565 |
Kind Code |
A1 |
Hart, Steven James ; et
al. |
February 21, 2002 |
Multi-directional cutters for drillout bi-center drill bits
Abstract
A drillout bi-center bit includes first and second axes of
rotation separated by a distance D, a first region of radius D
centered on one of the axes of rotation, a second region of radius
D centered on the other of the axes of rotation, and a third region
defined by the overlap between the first and second regions,
wherein the cutters provided within the third region are designed
to withstand cutting in opposing cutting directions. This may be
achieved by providing each cutter with two cutting faces, or by
providing two groups of cutters, one group arranged to cut in one
direction, the other group being designed to cut upon rotation in
the other direction, one of the groups protruding from the bit body
of the bit to a greater depth than the other group.
Inventors: |
Hart, Steven James; (Bath,
GB) ; Watson, Graham R.; (Frampton on Severn, GB)
; Daly, Jeffery E.; (Cypress, TX) |
Correspondence
Address: |
SCHLUMBERGER OILFIELD SERVICES
JEFFREY E. DALY
7211 N. GESSNER
HOUSTON
TX
77040
US
|
Family ID: |
22851532 |
Appl. No.: |
09/682193 |
Filed: |
August 3, 2001 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
60227049 |
Aug 21, 2000 |
|
|
|
Current U.S.
Class: |
175/385 ;
175/398 |
Current CPC
Class: |
E21B 10/5673 20130101;
E21B 10/5676 20130101; E21B 10/43 20130101; E21B 10/26
20130101 |
Class at
Publication: |
175/385 ;
175/398 |
International
Class: |
E21B 010/26 |
Claims
We claim:
1. A drillout bi-center drill bit comprising a bit body with a
first end adapted to be detachably secured to a drill string, a
pilot section on a second, opposite end of the bit body, a reamer
section intermediate the first and second ends, and a drilling face
on the pilot section; a first drilling center of rotation of the
pilot section; a second, passthrough center of rotation of the
pilot section spaced apart from the first center of rotation by a
non-zero distance D; a first region of the drilling face centered
about the first center of rotation having a radius D, a second
region of the drilling face centered about the second center of
rotation having a radius D, and a third region of the drilling face
formed by the intersection of the first region and the second
region; a cutting element being fixed on the bit body within the
third region, the cutting element having a first cutting face
generally oriented perpendicular to the direction of travel of the
cutting element about the first center of rotation of the pilot
section and a second cutting face generally oriented perpendicular
to the direction of travel of the cutting element about the second
center of rotation.
2. The drillout bi-center drill bit of claim 1, wherein the cutting
element is formed of cemented tungsten carbide.
3. The drillout bi-center drill bit of claim 1, wherein the cutting
element is formed of an infiltrated material comprising metallic
powders mixed with diamond particles and a binder.
4. The drillout bi-center drill bit of claim 1, wherein a
polycrystalline diamond compact cutter is mounted on one of the
cutting faces of the cutting element.
5. The drillout bi-center drill bit of claim 1, wherein the cutting
element is of generally conical form, the first and second cutting
faces being defined by different parts of a generally conical
surface of the cutting element.
6. A drillout bi-center drill bit comprising a bit body with a
first end adapted to be detachably secured to a drill string, a
pilot section on a second, opposite end of the bit body, a reamer
section intermediate the first and second ends, and a drilling face
on the pilot section; a first drilling center of rotation of the
pilot section; a second, passthrough center of rotation of the
pilot section spaced apart from the first center of rotation by a
non-zero distance D; a first region of the drilling face centered
about the first center of rotation having a radius D, a second
region of the drilling face centered about the second center of
rotation having a radius D, and a third region of the drilling face
formed by the intersection of the first region and the second
region; a plurality of first cutters being positioned in the third
region, each with superhard cutting faces generally oriented
perpendicular to the direction of travel of their respective first
cutters about the first center of rotation, said first cutters
projecting a distance from the bit body; at least one second cutter
on the bit body within the third region and projecting a distance
from the bit body greater than the projection of the first cutters,
with a cutting face orientated generally perpendicular to the
direction of travel of the second cutter about the second center of
rotation.
7. The drillout bi-center drill bit of claim 6, wherein the at
least one of second cutters is formed of cemented tungsten
carbide.
8. The drillout bi-center drill bit of claim 6, wherein a
polycrystalline diamond compact cutter is mounted on one of the
cutting faces the at least one of the second cutters is of an
infiltrated material comprising a mixture of metallic powders,
diamond particles and a binder.
9. The drillout bi-center drill bit of claim 6, wherein the bit
body is of infiltrated powdered metal matrix form and is shaped to
define the or each second cutter.
10. The drillout bi-center drill bit of claim 6, wherein a
polycrystalline diamond compact cutter is mounted on the cutting
face of the at least one of said second cutters.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority from U.S. Provisional
Patent Application No. 60/227,049 filed Aug. 21, 2000.
BACKGROUND OF INVENTION
[0002] 1. Field of the Invention.
[0003] The present invention relates generally to drill bits, and,
more particularly, to multi-directional cutters for a fixed cutter,
drillout bi-center bit.
[0004] 2. Description of the Related Art.
[0005] In the pursuit of drilling boreholes into the earth for the
recovery of minerals, there are instances when it is desirable to
drill a borehole with a diameter larger than the bit itself. Drill
bits used to form these boreholes are generally known as bi-center
type drill bits.
[0006] Bi-center drill bits are well known in the drilling
industry. Various types of bi-center drill bits are described in
U.S. Pat. Nos. 1,587,266, 1,758,773, 2,074,951, 2,953,354,
3,367,430, 4,408,669, 4,440,244, 4,635,738, 5,040,621, 5,052,503,
5,165,494, 5,678,644 and European Patent Application 0,058,061 all
herein incorporated by reference.
[0007] Modern bi-center drill bits are typically used in difficult
drilling applications where the earth formations are badly
fractured, where there is hole swelling, where the borehole has a
tendency to become spiraled, or in other situations where an
oversize hole is desirable.
[0008] In these difficult drilling applications, the top portion of
the well bore is often stabilized by setting and cementing casing.
The cement, shoe, float, and related cementing hardware are then
typically drilled out of the casing by a drill bit that is run into
the casing for this purpose. Once the cement and related hardware
are drilled out, the drillout bit is tripped out of the hole and a
bi-center drill bit is run back into the borehole. Drilling then
proceeds with the bi-center drill bit, which drills a hole into the
formation below the casing with a diameter that is greater than the
inside diameter of the casing.
[0009] To reduce drilling expenses, attempts have been made to
drill the cement and related hardware out of the casing, and then
drill the formation below the casing with a single bi-center drill
bit. These attempts often resulted in heavy damage to both the
casing and the bi-center drill bit.
[0010] The casing tends to be damaged by the gauge cutting elements
mounted on the bi-center drill bit because inside the casing the
pilot section of the bit is forced to orbit about its center,
causing the gauge cutters to engage the casing. The forced orbiting
action of the pilot section can also cause damage to the cutters on
the leading face of the bi-center drill bit.
[0011] As is well known in fixed cutter drill bits, the cutting
elements have cutting faces which are precisely oriented relative
to the direction of travel of the cutter through the formation
being drilled. However, cutters located in an area generally
between the passthrough center and the drilling center of the bit
face of drillout bi-center bits experience two different directions
of travel as they drill. One direction of travel occurs when the
bit is drilling out, and the other direction of travel occurs when
the bit is drilling the full diameter borehole. The cutters which
lie in line between the two centers, in fact, experience exactly
opposite directions of travel.
[0012] As previously stated, this has caused severe damage to the
cutters in this area in the past. The typical solution to this
problem has been to leave this area of the face of the bit devoid
of cutters. Unfortunately, in some bi-center bit designs,
particularly bi-center bits with large differences between the
passthrough diameter and the drilling diameter, leaving this region
devoid of cutters may cause the drilling performance of the bit to
suffer.
[0013] The present invention is directed to overcoming, or at least
reducing the effects of, one or more of the problems set forth
above.
SUMMARY OF INVENTION
[0014] In one aspect of the present invention, there is provided a
drillout bi-center drill bit comprising a bit body with a first end
adapted to be detachably secured to a drill string, a pilot section
on a second, opposite end of the bit body and a reamer section
intermediate the first and second ends. There is a first drilling
center of rotation of the pilot section and a second passthrough
center of rotation of the pilot section spaced apart from the first
center of rotation by a non-zero distance D. There is also a first
region of the pilot section centered about the first center of
rotation having a radius D, a second region of the pilot section
centered about the second center of rotation having a radius D, and
a third region of the pilot section formed by the intersection of
the first region and the second region. A cutting element is fixed
on the bit body within the third region. The cutting element has a
first cutting face generally oriented perpendicular to the
direction of travel of the cutting element about the first center
of rotation of the pilot section and a second cutting face
generally oriented perpendicular to the direction of travel of the
cutting element about the second center of rotation.
[0015] In another aspect of the present invention, there is
provided a drillout bi-center drill bit comprising a bit body with
a longitudinal axis and a first end adapted to be detachably
secured to a drill string, a pilot section on a second, opposite
end of the bit body and a reamer section intermediate the first and
second ends. There is a first drilling center of rotation of the
pilot section and a second passthrough center of rotation of the
pilot section spaced apart from the first center of rotation by a
non-zero distance D. There is a first region of the pilot section
centered about the first center of rotation having a radius D, a
second region of the pilot section centered about the second center
of rotation having a radius D, and a third region of the pilot
section formed by the intersection of the first region and the
second region. There are a plurality of first cutters in the third
region, with superhard cutting faces generally oriented
perpendicular to the direction of travel of the cutting element
about the first center of rotation, projecting a distance from the
bit body. At least one second cutter is fixed on the bit body
within the third region and projecting a distance from the bit body
greater than the projection of the first cutters, with a cutting
face oriented generally perpendicular to the direction of travel of
the second cutter about the second center of rotation.
BRIEF DESCRIPTION OF DRAWINGS
[0016] The invention may be best understood by reference to the
following description taken in conjunction with the accompanying
drawings, in which like reference numerals identify like elements,
and in which:FIG. 1 provides a perspective view of a drillout
bi-center drill bit in accordance with one embodiment of the
present invention; FIGS. 2A, 2B and 2C show side views perspectives
of the drillout bi-center drill bit of FIG. 1; FIG. 3 shows an end
view perspective of the drillout bi-center drill bit of FIG. 1;
FIG. 4A shows an end view perspective of the drillout bi-center
drill bit of FIG. 1 illustrating the iris shaped third region; FIG.
4B shows a simplified end view of the iris shaped third region of
the drillout bi-center drill bit of FIG. 4A; FIGS. 5-7 show
perspective views of various cutting elements that are mounted in
the iris shaped third region on the drillout bi-center drill bit in
accordance with the present invention; FIG. 8 is a partial end view
of the face of the drillout bi-center drill bit showing an
alternate cutter arrangement in accordance with another embodiment
of the present invention; FIG. 9 shows a perspective view of a
cutting element of the embodiment of the drillout bi-center drill
bit of FIG. 8; FIG. 10 shows a perspective view of still another
cutter arrangement in accordance with another embodiment of the
present invention.
[0017] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that the description
herein of specific embodiments is not intended to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
DETAILED DESCRIPTION
[0018] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers" specific goals, such as compliance with
system-related and business-related constraints, which will vary
from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure.
[0019] Turning now to the drawings, and specifically referring to
FIGS. 1, 2A, 2B, and 2C, a drillout bi-center drill bit 10 having
multi-directional cutters is shown in accordance with one
embodiment of the present invention. The drillout bi-center drill
bit 10 has a longitudinal axis 11 upon which the drill bit 10
rotates, and a bit body 12 with a first end 14 adapted to be
secured to a drill string (not shown) for driving the drill bit 10.
According to one embodiment, threads 16 may be used for coupling
the drill bit 10 to the drill string. However, it will be
appreciated to those of ordinary skill in the art that various
other forms of attachment may be used in lieu of the threads 16
without departing from the spirit and scope of the present
invention. At a second, opposite end of the bit body 12 is a pilot
section 18 of the drillout bi-center drill bit 10 with an exposed
drilling face 17. A reamer section, shown generally by numeral 20,
is intermediate the first end 14 and the pilot section 18 of the
bi-center drill bit 10.
[0020] While in operation, the bit body 12 is rotated via the drill
string by some external means while the drillout bi-center drill
bit 10 is forced into the material being drilled. The rotation
under load causes cutting elements 24 exposed at the drilling face
17 to penetrate into the drilled material and remove the material
in a scraping and/or gouging fashion.
[0021] In accordance with one embodiment of the present invention,
the bit body 12 includes internal passaging (not shown) that allows
pressurized drilling fluid to be supplied from the drilling surface
to a plurality of nozzle orifices 22. These nozzle orifices 22
discharge the drilling fluid to clean and cool the cutting elements
24 as they engage the material being drilled. The drilling fluid
also functions to transport the drilled material to the surface for
disposal.
[0022] According to one embodiment, the pilot section 18 may have a
section with at least one fluid passage 26 provided for return flow
of the drilling fluid. There also may be other fluid passages 26
provided in the reamer section 20 of the drillout bi-center drill
bit 10 as well.
[0023] Referring specifically to FIGS. 2B and 2C, side view
perspectives of the drillout bi-center drill bit 10 of the present
invention are shown. One important characteristic of the drillout
bi-center drill bit 10 is its ability to drill a borehole 11 into
the earth 13 with a gauge drilling diameter larger than the inside
diameter of the casing 15, or pipe or other type of conductor the
bit 10 passes through, which is shown in FIG. 2C.
[0024] Another important characteristic of the of the drillout
bi-center drill bit 10 is its ability to drill out cement 19 (and
related hardware, not shown) inside the casing 15 as shown in FIG.
2B without causing damage to the casing 15 or the cutting elements
24 of the drill bit 10.
[0025] Turning now to FIG. 3, an end view of a drillout bi-center
drill bit 10 of the present invention is shown. The gauge drilling
diameter, as indicated by the circle 28, is generated by radius R1
from a first center of rotation 30 of the pilot section 18. In this
drilling mode, the circular portion of the pilot section 18 will be
concentric with the diameter 28. The cutting elements 24 on the
portion of the reamer section 20 radially furthest from the first
center of rotation 30 actually drills the gauge drilling diameter
of the borehole 11, as indicated at numeral 31. The reamer section
20 is formed eccentrically of the pilot section 18, so only a
portion of the wall of the borehole 11 is in contact with the
cutting elements 24, which cut the final gauge of the borehole 11
at any given time during operation.
[0026] The drillout bi-center drill bit 10 also has a passthrough
diameter, as indicated by the circle 32, generated by radius R2
from a second center of rotation 34 of the pilot section 18. The
shortest linear distance at the face of the bit between the centers
of rotation 30, 34 is indicated as non-zero distance D. The second
center of rotation 34 is on the centerline of the smallest cylinder
that may be fitted about the drillout bi-center drill bit 10. To be
effective, the passthrough diameter that is indicated by circle 32
must be smaller than the inside diameter of the casing 15 that the
drillout bi-center drill bit 10 must pass through.
[0027] For optimal life, the cutting elements 24 must be oriented
on the pilot section 18 in a known manner with respect to the
direction of scraping through the material being drilled. This is
no problem for bi-center drill bits that do not drill the cement 19
and related hardware out of the casing. However, when a drillout
bi-center drill bit is drilling the cement 19 and related hardware
in the casing, some of the cutting elements 24 may be subjected to
reverse scraping while rotating about the second center of rotation
34. Reverse scraping often causes rapid degradation of the cutting
elements 24.
[0028] The cutting elements 24 are typically polycrystalline
diamond compact cutters or PDC. A PDC is typically comprised of a
facing table of diamond or other superhard substance bonded to a
less hard substrate material, typically formed of but not limited
to, tungsten carbide. The PDC is then often attached by a method
known as long substrate bonding to a post or cylinder for insertion
into the bit body 12. This PDC type of cutting element 24 is
particularly sensitive to reverse scraping because loading from
reverse scraping can easily destroy both the diamond table bonding
and the long substrate bonding.
[0029] In prior art drill bits, the cutting elements are typically
configured with a single cutting surface, where the cutting surface
is properly oriented to cut through material being drilled when the
drill bit rotates around a first center of rotation, such as center
of rotation 30, for example. However, when the drillout bi-center
drill bit 10 rotates around a second center of rotation, such as
center of rotation 34, for example, the cutting surface of the
cutting element is not properly oriented to optimally cut through
the drilled material. That is, when the cutting element is
configured with this single cutting surface, the drill bit is
optimally utilized while drilling around the first center of
rotation, but is not optimally positioned to cut material when the
drill bit rotates around a second center of rotation. With this
particular prior art configuration, the cutting element will
undesirably wear at a faster rate when the drill bit is rotating
around the center of rotation where the single cutting surface of
the cutting element is not optimally positioned to cut material. As
a result of the cutting elements wearing at a faster rate, the life
of the drill bit is undesirably shortened.
[0030] As previously stated, the distance D is the shortest linear
distance between center of rotation 30 and center of rotation 34.
As shown in FIG. 4A, a first region 56 of the pilot section 18,
centered about the first center of rotation 30, has a radius D. A
second region 58 of the pilot section 18 is centered about the
second center of rotation 34, and also has a radius D. A third
region 60 of the pilot section 18 is formed by the intersection of
the first region 56 and the second region 58. This iris shaped
third region 60 is the critical area where reverse cutter scraping
is possible.
[0031] Turning now to FIG. 4B, a perspective view of cutting
elements of the embodiment of the drillout bi-center drill bit of
FIG. 8 is shown. Three cutting elements 72, 74, 76 (FIGS. 5-7) of
the present invention are shown in the iris shaped third region 60
between the drilling center of rotation 30 and the passthrough
center of rotation 34.
[0032] Cutter 72 has two cutting faces 78, 80. When the drillout
bi-center drill bit 10 is rotating about the drilling center of
rotation 30, cutting face 80 of cutter 72 is properly oriented for
cutting along the path indicated by arrow 82. Cutting face 80 is
generally oriented perpendicular to the direction of travel of the
cutter 72 in this operating mode, which is parallel to dashed line
86 passing through about the drilling center of rotation 30.
[0033] In a similar manner, when the drillout bi-center drill bit
10 is rotating about the passthrough center of rotation 34, cutting
face 78 of cutter 72 is properly oriented for cutting along the
path indicated by arrow 84. Cutting face 78 is generally oriented
perpendicular to the direction of travel of the cutter 72 in this
operating mode, which is generally parallel to dashed line 88
passing through about the passthrough center of rotation 34.
[0034] Cutter 72 may be formed of any material suitable for
drilling earth formations. Since the wear rate of cutting elements
near the center of the bit is generally low, cemented tungsten
carbide may be a suitable material. It is understood that during
drillout operation, only a small amount of wear is likely to occur
on cutting face 78 of cutter 72. It would be expected that much
more wear would occur on face 80 when the bit is drilling into the
earth. If the wear rates are unacceptably high, the cutter 72 may
be formed of an infiltrated material comprising metallic powders
such as tungsten carbide mixed with diamond particles and a
binder.
[0035] Cutter 74 operates in a manner similar to cutter 72,
although as described later, cutter 74 is intended for much more
abrasive drilling than cutter 72. Cutter 74 has two cutting faces
90, 92. When the drillout bi-center drill bit 10 is rotating about
the drilling center of rotation 30, cutting face 90 of cutter 74 is
properly oriented for cutting along the path indicated by arrow 94.
Cutting face 90 is generally oriented perpendicular to the
direction of travel of the cutter 74 in this operating mode which
is parallel to dashed line 98 passing through about the drilling
center of rotation 30.
[0036] In a similar manner, when the drillout bi-center drill bit
10 is rotating about the passthrough center of rotation 34, cutting
face 92 of cutter 74 is properly oriented for cutting along the
path indicated by arrow 96. Cutting face 92 is generally oriented
perpendicular to the direction of travel of the cutter 74 in this
operating mode which is parallel to dashed line 100 passing through
about the passthrough center of rotation 34.
[0037] In order to survive severe, abrasive drilling conditions the
cutting face 90 of cutter 74 is quite different from that of cutter
72. A PDC cutting element 102 is mounted on cutting face 90 a small
distance 104 from the end 106 of cutter 74 exposed at the drilling
face 17 of the drillout bi-center drill bit 10. During the drillout
phase, a small amount of wear will occur on end 106. After
drillout, the bit will then start drilling a full diameter hole in
the earth. However, in abrasive drilling conditions, even cutters
near the center will wear rapidly. Therefore, the end 106 of cutter
74 will wear rapidly, exposing the PDC element 102. Once this
happens, the cutter will wear at a rate comparable to other PDC
cutters near the center.
[0038] In this embodiment, the PDC is attached to the cutter 74 by
a method known as long substrate bonding. The cutter 74 is then
inserted into the bit body 12, which gives the PDCs an alternative
orientation with respect to the center of rotation about which the
drill bit 10 rotates.
[0039] It should be apparent that cutters 72 and 74 will generally
have different orientations of cutting faces 78, 80, 90, 92
depending where they are located within the iris shaped third
region 60 between the drilling center of rotation 30 and the
passthrough center of rotation 34. Although some mismatch of
cutting faces 78, 80, 90, 92 would be tolerated, allowing some
commonality of cutting face orientations, many different
configurations of cutters 72 and 74 would still be necessary for
most drillout bi-center drill bits 10.
[0040] Another embodiment of the invention which can be placed
anywhere in the iris shaped third region 60, a cone shaped cutter
76 suitable for very non-abrasive drilling condition, is shown in
FIG. 7. In cutter 76, the side 108 is generally conic and may
terminate in a flat top 110 that is also exposed at the drilling
face 17. Since these cutters 76 are generally symmetrical, they may
be placed anywhere within the iris shaped third region 60 between
the drilling center of rotation 30 and the passthrough center of
rotation 34. In this cutter 76, the cutting edge 112 is the
intersection of the side 108 and the flat top 110. Since cutter 76
is generally symmetrical, both drillout and passthrough drilling
are readily accomplished. Although not particularly "sharp", cutter
76 is suitable for non-abrasive drilling conditions.
[0041] Shown in FIG. 8 is a particular bit configuration where the
cutting functions for drillout and full diameter drilling are
embodied in separate cutters. Two drilling face sections 17 are
shown on bit body 12. A plurality of conventional cutters 24 is
shown with arrows 114 indicating their path of rotation about the
drilling center of rotation 30. A plurality of cutters 116 (shown
in FIG. 9) have cutting faces 118 oriented for drilling out, with
arrows 119 indicating their path of rotation about the passthrough
center of rotation 34.
[0042] The tops 120 of cutters 116 are orientated relatively
farther from the bit body 12 than the remainder of cutters 24 on
the drilling face section 17 of the drillout bi-center bit 10.
Therefore the cutting faces 118 of cutters 116 will engage the
drillout material and prevent damage to cutters 24 during drillout.
Once drillout is complete, the cutters 116 will rapidly wear,
allowing the cutters 24 to drill normally. The operation is
therefore effectively the same as cutter 74. Cutter 116 may be
formed of any material suitable for drilling earth formations.
However, similar to cutter 74, a cemented tungsten carbide material
or an infiltrated material comprising metallic powders such as
tungsten carbide mixed with diamond particles and a binder is
suitable. In this embodiment and similar to cutters 72, 74 and 76
the cutter 116 is oriented as necessary then fixed into the bit
body 12.
[0043] An alternate embodiment for the arrangement of the drillout
cutters shown in FIG. 8 is possible when the bit body 12 is an
infiltrated powdered metal matrix material. When this is the case,
the cutter 122 is formed as a bump in the matrix of the bit body
12. The cutting face 118, and top 120, of cutter 122 function
identically to cutter 116. However, because matrix bits are made in
a molding process, orienting and fixing the cutters 122 into the
bit body 12 is not necessary. Cutter 122 is integral with the bit
body. Methods of construction of matrix drill bits are well known
in the art. Accordingly, the specific details of such will not be
disclosed herein to avoid unnecessarily obscuring the present
invention.
[0044] The particular embodiments disclosed above are illustrative
only, as the invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art having
the benefit of the teachings herein. Furthermore, no limitations
are intended to the details of construction or design herein shown,
other than as described in the claims below.
[0045] Whereas the present invention has been described in
particular relation to the drawings attached hereto, it should be
understood that other and further modifications apart from those
shown or suggested herein, may be made within the scope and spirit
of the present invention.
* * * * *