U.S. patent application number 10/064817 was filed with the patent office on 2004-01-15 for cutter and method of manufacture thereof.
Invention is credited to Griffin, Nigel Dennis.
Application Number | 20040007394 10/064817 |
Document ID | / |
Family ID | 29731615 |
Filed Date | 2004-01-15 |
United States Patent
Application |
20040007394 |
Kind Code |
A1 |
Griffin, Nigel Dennis |
January 15, 2004 |
Cutter and method of manufacture thereof
Abstract
A polycrystalline diamond cutter and method of manufacturing a
polycrystalline diamond cutter is disclosed. The method of
manufacture comprising assembling a first substrate component, a
second notched substrate component and diamond crystals into a
desired configuration. The assembly is subjected to high
temperature and high pressure conditions to cause the diamond
crystals to bond to one another and to the first and second
substrate components. The method forms a cutter having a single
body of polycrystalline diamond bonded to the substrate
components.
Inventors: |
Griffin, Nigel Dennis;
(Nympsfield, GB) |
Correspondence
Address: |
GRANT PRIDECO, L.P.
JEFFREY E. DALY
1330 POST OAK BLVD. SUITE 2700
HOUSTON
TX
77056
US
|
Family ID: |
29731615 |
Appl. No.: |
10/064817 |
Filed: |
August 21, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10064817 |
Aug 21, 2002 |
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10064428 |
Jul 12, 2002 |
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Current U.S.
Class: |
175/434 ;
75/240 |
Current CPC
Class: |
E21B 10/573
20130101 |
Class at
Publication: |
175/434 ;
75/240 |
International
Class: |
E21B 010/36 |
Claims
What is claimed is:
1. A method of manufacturing a cutter comprising a first substrate
component, and a second substrate component, the method comprising
providing one or more notches in the second substrate component and
assembling the first substrate component and the second substrate
component and diamond crystals into a desired configuration, and
subjecting the assembly to high temperature and high pressure
conditions to cause the diamond crystals to bond to one another and
to the first and second substrate components to form a cutter
having a single body of polycrystalline diamond.
2. A method according to claim 1, wherein the first and second
substrate components engage one another.
3. A method according to claim 1, wherein the first and second
substrate components are spaced apart from one another, some of the
diamond crystals being located between the first and second
substrate components.
4. A method according to claim 1, further comprising assembling at
least a third substrate component with the first and second
substrate components and diamond crystals.
5. A method according to claim 1, further comprising locating the
first and second substrate components and diamond crystals within a
container prior to subjecting the assembly to high pressure, high
temperature conditions.
6. A method according to claim 1, further comprising including a
binder catalyst material in the assembly.
7. A method according to claim 6, wherein the binder catalyst
material is an iron group element.
8. A method according to claim 7, wherein the binder catalyst
material is cobalt.
9. A method according to claim 1, wherein the first substrate
component is generally cylindrical and the second substrate
component is of part-annular form.
10. A method according to claim 1, wherein the first substrate
component is of grooved form.
11. A cutter comprising a first substrate component, a notched
second substrate component and a single table of polycrystalline
diamond which is bonded to the first and second substrate
components.
12. A cutter according to claim 11, further comprising at least one
additional substrate component, the polycrystalline diamond table
being bonded to the or each additional substrate component.
13. A cutter according to claim 11, wherein the first substrate
component is of generally cylindrical form and the second substrate
component is of part-annular form.
14. A cutter according to claim 11, wherein the first and second
substrate components engage one another.
15. A cutter according to claim 11, wherein the first and second
substrate components are spaced apart from one another.
16. A cutter according to claim 15, wherein the polycrystalline
diamond table extends between the first and second substrate
components.
17. A cutter according to claim 11, wherein the first substrate
component is grooved.
18. A method of manufacturing a cutter comprising forming an
assembly by locating a powdered substrate component material,
diamond crystals and a first substrate component within a container
in a desired configuration, and subjecting the assembly to high
temperature and high pressure conditions to cause the powdered
substrate component material to form a second, notched substrate
component and the diamond crystals to bond to one another and to
the first and second substrate components to form a cutter having a
single body of polycrystalline diamond.
19. A method according to claim 18, further comprising including a
binder catalyst material in the assembly.
20. A method according to claim 19, wherein the binder catalyst
material is an iron group element.
21. A method according to claim 20, wherein the binder catalyst
material is cobalt.
22. A method according to claim 18, wherein the powdered substrate
component material is located to form an additional, third
substrate component.
Description
CROSS REFERENCE TO RELATED APPLICATIONS This application is a
Continuation-in-Part of U.S. patent application Ser. No. 10/064,428
filed on Jul. 12, 2002 by Nigel Griffin.
BACKGROUND OF INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a cutter, and to a method of
manufacture thereof. The invention relates, in particular, to a
cutter suitable for use on a drill bit for the formation of
subterranean well bores. It will be appreciated that the cutter may
alternatively be used in other applications.
[0003] 2. Description of the Related Art
[0004] One form of drill bit for use in the formation of
subterranean wellbores comprises a bit body having a first end
provided with a plurality of generally radially extending
upstanding blades and a second end adapted to be secured to a drill
string. Each of the blades carries a plurality of cutters. The
cutters typically each comprise a tungsten carbide or other
metallic substrate to which is bonded a layer of a superhard
material, for example polycrystalline diamond. The substrate may be
bonded directly to the bit body, or alternately may be bonded to a
relatively long substrate which, in turn, is secured to the bit
body.
[0005] In another form of drill bit, cutters are mounted upon
rotatable cones mounted upon a bit body. Each cutter is typically
manufactured by placing a sintered tungsten carbide substrate and
diamond crystals into a container with a suitable binder catalyst
material, and subjecting the container to high pressure, high
temperature conditions such that the diamond crystals bond to one
another and to the substrate.
[0006] A number of different designs of cutter are known, the
different designs arising from, for example, the use of substrates
of different shapes. In one example, the substrate includes an
upstanding peripheral wall extending around most, but not all of
the circumference of the substrate. A cutter manufactured using a
substrate of this shape includes a polycrystalline diamond table
which only extends to the periphery of the cutter at the region
where the peripheral wall is absent as shown in FIGS. 1 and 2. It
has been found that in cutters of this type there is a tendency for
the polycrystalline diamond table to crack. This is thought to be
as a result of hoop stresses.
[0007] A number of cutter designs provide the cutter with two or
more cutting surfaces. This is achieved, in some designs, by
providing two separate substrates, a first diamond layer located
between the substrates and a second, isolated diamond layer located
upon the second substrate. This type of cutter is shown in U.S.
Pat. No. 5,722,499 and U.S. Pat. No. 5,667,028, both incorporated
by reference herein for all they disclose. Another design includes
separate diamond layers formed by providing grooves in the outer
periphery of the substrate and introducing diamond crystals into
the grooves prior to undertaking the high temperature high pressure
process. Cutters of this type are illustrated in U.S. Pat. No.
5,979,578 and U.S. Pat. No. 5,667,028, both incorporated by
reference herein for all they disclose. It will be appreciated
that, in these arrangements, two or more independent, isolated
regions of polycrystalline diamond are formed.
SUMMARY OF INVENTION
[0008] The present invention provides a cutter with a reduced
tendency for the polycrystalline diamond table to crack, and a
method for manufacture of such a cutter.
[0009] According to the present invention there is provided a
method of manufacturing a cutter comprising assembling a first
substrate component, a second substrate component and diamond
crystals into a desired configuration, and subjecting the assembly
to high temperature and high pressure conditions to cause the
diamond crystals to bond to one another and to the first and second
substrate components to form a cutter having a single body of
polycrystalline diamond.
[0010] The first and second substrate components may be arranged to
engage one another, or alternatively may be separated from one
another by at least some of the diamond crystals prior to
subjecting the assembly to high temperature, high pressure
conditions.
[0011] The first and second substrate components are preferably of
sintered tungsten carbide form. However, this need not be the case
and other materials could be used. For example the second substrate
component could be of a STELLITE (R) material. A binder catalyst
material, for example cobalt, may be included in the assembly.
Although cobalt is the preferred binder catalyst material, other
iron group elements may be used, if desired. The binder catalyst
material may be included in either of the first and second
substrate components, or mixed with the diamond powder, or provided
in any combination of these locations.
[0012] Also disclosed is a cutter with a single diamond table
bonded to first substrate component of circular cross-section and
to a second substrate component of annular or part-annular form. At
least one further substrate component, for example of annular or
part annular form, may additionally be provided.
[0013] According to another aspect of the invention there is
provided a method of forming an assembly by locating a powdered
substrate component material, diamond crystals and a first
substrate component within a container in a desired configuration,
and subjecting the assembly to high temperature and high pressure
conditions to cause the powdered substrate component material to
form a second substrate component, and the diamond crystals to bond
to one another and to the first and second substrate components to
form a cutter having a single body of polycrystalline diamond.
[0014] The powdered substrate component material is preferably
powdered tungsten carbide. As mentioned hereinbefore, a binder
catalyst material may be provided, for example mixed with the
powdered substrate component material.
[0015] The configuration of the powdered substrate component
material within the assembly may be such as to result in the
formation of at least one additional substrate component. The
second and/or additional substrate components may be of annular or
part-annular form.
[0016] The invention also relates to a cutter manufactured using
either of the methods described hereinbefore.
BRIEF DESCRIPTION OF DRAWINGS
[0017] The invention will further be described, by way of example
only, with reference to the accompanying drawings.
[0018] FIG. 1 is a diagrammatic sectional view of a prior art
cutter.
[0019] FIG. 2 is an end view of the prior art cutter of FIG. 1.
[0020] FIG. 3 is a perspective view of a drill bit.
[0021] FIG. 4 is a perspective view of an alternative drill
bit.
[0022] FIGS. 5 and 6 are views similar to FIGS. 1 and 2 showing a
cutter in accordance with an embodiment of the invention.
[0023] FIG. 7 is a diagrammatic view illustrating part of the
manufacturing operation.
[0024] FIGS. 8 to 25 are cross-sectional and side views of other
embodiments.
[0025] FIG. 26 is a view similar to FIG. 7 illustrating an
alternative manufacturing technique.
[0026] FIG. 27 is a view of one orientation of the notches on the
second substrate components.
[0027] FIG. 28 is a view of a second orientation of the notches on
the second substrate components.
[0028] FIG. 29 is a partial view of an enlargement of the second
substrate components showing a configuration of a notch.
DETAILED DESCRIPTION
[0029] Referring now to FIG. 3 there is shown a drill bit for use
in the formation of subterranean wellbores. The drill bit comprises
a bit body 10 having a first end 12 upon which a plurality of
blades 14 are provided, the blades 14 upstanding from the first end
12 and extending in generally radial directions. The bit body 10
further includes a second end 16 adapted to permit the drill bit to
be secured to the remainder of a drill string whereby the drill bit
can be driven for rotation about its longitudinal axis 18. Each of
the blades 14 is provided with a plurality of cutters 20, each of
the cutters 20 being arranged to engage the formation being drilled
using the drill bit, in use, such that the combination of rotation
of the drill bit and the application of a load, in a generally
axial direction, upon the drill bit causes the cutters to scrape
the material from the formation. The drill bit further includes a
plurality of nozzles 22 supplied with fluid and arranged such that,
in use, fluid supplied through the nozzles 22 serves to clean the
cutters and to carry the material removed by the cutters away from
the drill bit.
[0030] As is common practice with drill bits of this type, the
drill bit includes a gauge region 24. In the arrangement shown, the
gauge region 24 is provided with a plurality of inserts 26 intended
to enhance the ability of the drill bit to withstand wear of the
gauge region.
[0031] FIG. 4 illustrates an alternative type of drill bit. In the
drill bit of FIG. 4, the bit body 110 has an upper portion 116
which form legs 124 shaped to define mounting regions which in turn
carry rotatable rollers 128 of generally conical form. Each of the
rollers 128 is provided with a plurality of cutters 120. As with
the drill bit illustrated in FIG. 3, in use, the drill bit of FIG.
4 is rotated about its axis 118. With the drill bit of FIG. 4, such
rotation causes the rollers 128 to rotate about their own axes,
this movement causing the cutters 120 to engage and scrape against
the formation being drilled to remove material therefrom which, as
in the arrangement illustrated in FIG. 3, is removed by the
application of drilling fluid. Similar to the drill bit of FIG. 3,
gauge inserts 126 are also provided.
[0032] Cutters 20, 120 may have various shapes and sizes as shown.
However, for ease of understanding, the references and explanations
for cutters 20 in this specification apply equally to cutters 120,
as both types may be useful in both types of drill bits shown. The
cutters 20, 120 may also be useful in numerous other type of down
hole tools and other devices employing highly wear resistant
cutting elements.
[0033] FIGS. 5 and 6 illustrate one of the cutters of the drill
bits shown in FIGS. 3 and 4. The cutter 20 shown in FIG. 5
comprises a first tungsten carbide substrate component 30 of
generally cylindrical form, a second substrate component 32, also
of tungsten carbide, and of part-annular form as shown in FIG. 6,
and a polycrystalline diamond table 34. The cutter 20 is
manufactured by placing the second substrate component 32 into part
of a suitable container 36, positioning powdered diamond crystals
34a in the region in which the table 34 of polycrystalline diamond
is to be formed, and positioning the first substrate component 30
onto the second component 32 and diamond crystals 34a. The
container 36 is then closed and sealed, as shown in FIG. 7, the
assembly then being subjected to high temperature, high pressure
conditions to cause the diamond crystals 34a to bond to one another
and to the first and second substrate components 30, 32. It will be
appreciated that the formation of such bonds results in the
production of the polycrystalline diamond table 34. In order for
the table 34 of polycrystalline diamond to form, the assembly shown
in FIG. 7 may further include a quantity of a suitable binder
catalyst material. Typically, the binder catalyst material takes
the form of cobalt. However, a number of other materials could be
used. In particular, any iron group element may be used as the
binder catalyst material. The binder catalyst material may be
introduced into the assembly by mixing the binder catalyst material
with the diamond crystals 34a, or by incorporating the binder
catalyst material into one or other, or both of the first and
second substrate components 30, 32, or by including the binder
catalyst material in the material of the container 36, or by a
combination of these techniques. Where the binder catalyst material
is included in the substrate components, it will be appreciated
that it infiltrates into the diamond material during the high
pressure high temperature operation.
[0034] After completion of the high temperature, high pressure
sintering operation, the container 36 is removed and the cutter
subjected to a suitable machining operation, if desired.
[0035] It will be appreciated that the cutter 20 manufactured using
this technique and as shown in FIGS. 5 and 6 is similar in
appearance to the known cutter shown in FIGS. 1 and 2. However, the
use of the two-part substrate results in the application of
significantly lower magnitude hoop stressing to the polycrystalline
diamond table, the separate second substrate component 32 being
more compliant than arrangements in which a single substrate is
used, and as a result the risk of cracking of the polycrystalline
diamond table is significantly reduced.
[0036] Although the technique described hereinbefore with reference
to FIGS. 5, 6 and 7 can be used to produce a cutter 20 which is
similar to that of FIGS. 1 and 2, the same technique may be used to
manufacture a wide range of other cutter designs. A number of
possible cutter designs are shown in FIGS. 8 to 19. In the
arrangement illustrated in FIGS. 8 and 9, the first and second
substrate components 30, 32 are spaced apart from one another by a
part of the polycrystalline diamond table 34. It will be
appreciated that a cutter of this type may be produced simply by
positioning the second substrate component 32 within one part of
the container 36, introducing the diamond crystals 34a into the
container 36, the diamond crystals 34a extending over the second
substrate component 32, and then introducing the first substrate
component 30 so that diamond crystals 34a are located between the
substrate components 30, 32. The application of high pressure, high
temperature conditions to such an assembly will result in the
production of a cutter 20 of the type shown in FIGS. 8 and 9.
[0037] The prior cutters shown in FIGS. 1 and 2 have an overall
impact toughness averaging about 30 joules. Cutters 20 manufactured
as described, with the second substrate component 32 as shown in
FIGS. 5, 6, 7 and 9 have demonstrated a 30% (to about 40 joules)
improvement in impact toughness and accompanying reduction in
cracking of the diamond table compared to the prior cutters shown
in FIGS. 1 and 2. A still further improvement is obtained when
notches 33 are pre-formed in the second substrate component 32, as
shown in FIGS. 27-29.
[0038] The notches 33 allow the second substrate component 32 to
crack in a controlled manner during processing, allowing additional
relief of the stresses in the diamond table 34. Providing these
notches 33 for additional stress relief has resulted in an
additional 25% (to about 50 joules) improvement in impact toughness
over the cutters 20 made with un-notched second substrate
components 32. Stated differently, the second substrate component
32 with the notches 33 have a 60% improvement in impact toughness
over the prior cutters shown in FIGS. 1 and 2.
[0039] The notches 33 are formed into the second substrate
component 32 either during its manufacture or the notches 33 are
formed later by removing a portion of the material of the second
substrate component 32. The notches may be regularly spaced, as
shown in FIGS. 28 and 29 or they may be irregularly spaced
according to the size and orientation of the second substrate
component 32. The notches may be shaped with rounded ends 35 as
shown in FIG. 29, or may have a variety of end configurations. The
exact orientation of the notches is not particularly important,
provided they provide a predictable path for the expansion of the
second substrate component 32 during processing. This expansion
often, but not necessarily always, leads to the aforementioned
crack in the second substrate component 32 of the finished cutter
20 from the base of the notch 33 to the edge.
[0040] Accordingly, the method for manufacturing the cutters 20
comprising a first substrate component 30 and a second substrate
component 32 for this embodiment of the invention is providing one
or more notches in the second substrate component 32 and assembling
the first substrate component 30 and the second substrate component
32 and diamond crystals 34a into a desired configuration, and
subjecting the assembly to high temperature and high pressure
conditions to cause the diamond crystals 34a to bond to one another
and to the first and second substrate components 30, 32 to form a
cutter 20 having a single body of polycrystalline diamond 34.
[0041] FIGS. 10 and 11 illustrate a cutter 20 which is similar to
that of FIGS. 8 and 9 but in which an additional, third substrate
component 38 is located between the first and second substrate
components 30, 32. In this arrangement, the polycrystalline diamond
table 34 extends between the first and third substrate components
30, 38 and between the third and second substrate components 38,
32. The manufacturing process used in the formation of a cutter 20
of this type simply requires the introduction of the second
substrate component 32 into the container 36, the application of
diamond material into the container 36 covering the second
substrate component 32, the introduction of the third substrate
component 38 into the container 36, the application of more diamond
material to cover the third substrate component 38, and finally the
introduction of the first substrate component 30.
[0042] The arrangement shown in FIGS. 12 and 13 is similar to that
of FIGS. 10 and 11 but includes a fourth substrate component 42. A
further distinction between the arrangement of FIGS. 12 and 13 and
that of FIGS. 10 and 11 is that no diamond material is provided
between the various substrate components. It will be noted from
FIGS. 11 and 13 that in each of these arrangements, the angular
extent of the various part-annular substrate components are not
equal resulting in the formation of steps in the polycrystalline
diamond table 34. This need not be the case. The arrangement of
FIGS. 10 and 11 further differs from that of FIGS. 12 and 13 in
that, as shown in FIG. 12, the various part-annular substrate
components are of non-equal radial extent whereas in the
arrangement shown in FIG. 10, the second and third substrate
components 32, 38 are of equal radial extent.
[0043] Turning to the arrangement shown in FIGS. 14 and 15, the
second and fourth substrate components, 32, 42 are of equal radial
extent and equal angular extent, the third substrate component 38
being of smaller radial and angular extent with the result that the
polycrystalline diamond table 34 includes a radially extending
projection 34b around part of its periphery.
[0044] The arrangement shown in FIGS. 16 and 17 is similar to that
of FIG. 8, but differs therefrom in that the second substrate
component 32 is not located at the surface of the cutter, but
rather is buried within the polycrystalline diamond table 34.
[0045] In each of the arrangements described hereinbefore, the
first substrate component 30 is of generally cylindrical form
having a flat surface to which the other substrate components
and/or the polycrystalline diamond table 34 is bonded. This need
not be the case, and FIGS. 18 and 19 illustrate an arrangement in
which the surface of the first substrate component 30 is grooved.
As a result, an arrangement is possible in which in some areas of
the cutter 20, the second substrate component 32 rests directly
upon the first substrate component 30, and in other regions thereof
the second substrate component 32 is spaced from the first
substrate component 30. In the regions where the second substrate
component 32 is spaced from the first substrate component 30, as
shown in FIG. 19, then the polycrystalline diamond table 34 extends
between the first and second substrate components, 30, 32.
[0046] In each of the arrangements described hereinbefore, it is
important to note that the polycrystalline diamond table 34 is in
the form of a single element, rather than taking the form of two or
more separate components spaced apart and isolated from one another
by a component of the substrate.
[0047] Although the cutters 20 described hereinbefore are suitable
for use with drill bits of the type illustrated in FIG. 3, it will
be appreciated that by appropriate selection of the shape of the
cutter, similar cutters may find application in drill bits of the
type illustrated in FIG. 4. A cutter 20 more applicable for use in
a drill bit of the type illustrated in FIG. 4 is shown in FIG.
20.
[0048] The cutter 20 shown in FIG. 20 comprises a first tungsten
carbide substrate component 30 of generally cylindrical form but
having a domed upper surface 50, in the orientation illustrated. A
second substrate component 32 of annular form is positioned upon
the first substrate component 30, the space within the second
substrate component 32 containing a polycrystalline diamond table
34. The shapes of the second substrate component 32 and
polycrystalline diamond table 34 are such as to define a domed
surface 52. It will be appreciated that this type of cutter can be
manufactured using a technique very similar to those described
above.
[0049] It will be appreciated that a number of modifications can be
made to the cutter of FIG. 20, for example to change its shape so
that the surface 52 is of, for example, generally conical form.
Other variations include spacing the second substrate component 32
from the first substrate component 30, as shown in FIG. 21, or
including additional substrate components, as shown in FIG. 22. The
second and/or additional substrate components may be of annular or
part-annular form. Where they are of curved, part-annular, form
then depending upon their circumferential extent, two or more
components may be provided at the same axial position as shown in
FIG. 23.
[0050] With cutters of the type used on drill bits of the type
shown in FIG. 4, it is common to provide one or more transition
layers comprising a mixture of diamond and tungsten carbide between
the tungsten carbide substrate and the polycrystalline diamond
table. Such transition layers 54 may also be incorporated into the
cutters shown in FIGS. 20 to 23. The second substrate component may
be positioned upon the transition layer 54 or layers, for example
as shown in FIG. 24, or the transition layer 54 or layers may be at
least partially encircled by the second substrate component, for
example as shown in FIG. 25.
[0051] In each of the arrangements described hereinbefore, the
second and additional substrate components are of pre-sintered
tungsten carbide form. It will be understood the other materials
may be used, if desired. Where pre-sintered tungsten carbide
substrate components are used, during the high pressure high
temperature sintering operation the diamond will typically be
compressed to a greater extent than the pre-sintered substrate
components. This may result in, for example, a significant
machining operation being required to produce a cutter having a
flat or smooth face. It is thought that this effect may be reduced
by modifying the manufacturing technique so that, instead of
locating a pre-sintered second substrate component 32 with the
container 36, and where appropriate instead of using pre-sintered
third and fourth substrate components 38, 42, etc., a quantity of
powdered tungsten carbide 56 is positioned in the container 36, as
shown in FIG. 26, in the areas in which the second substrate
component 32, and where applicable the third and fourth substrate
components 38, 42, etc., are required.
[0052] Once assembled, the application of the assembly to the high
temperature, high pressure conditions will cause the second
substrate component 32, and the third and fourth components 38, 42,
etc., where applicable, to form as well as resulting in the
formation of the polycrystalline diamond table and the bonding of
the table to the first substrate component 30 and to the newly
formed substrate components 32, 38, 42. As in the arrangements
described hereinbefore, a binder catalyst material, typically
cobalt, may be provided. The binder catalyst material may be mixed
with the diamond powder, the tungsten carbide powder, the
pre-sintered first substrate component 30, or in any combination of
these locations.
[0053] During the manufacturing operation, the tungsten carbide
forming the second substrate component 32 and, where appropriate,
the additional substrate components, compresses at a rate similar
to the powdered diamond with the result that a short, less complex
machining operation may be required to produce a cutter with a
generally flat or smooth surface.
[0054] It will be appreciated that this technique may be used in
the manufacture of any of the cutters 20 described hereinbefore, or
modifications thereto.
[0055] Again, as previously described, in all the embodiments
described herein any of the secondary substrate components 32, 38,
42 which are performed may be provided with notches 33 to further
improve impact toughness.
[0056] 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.
* * * * *