Note: Descriptions are shown in the official language in which they were submitted.
¦i 124~62~ CHP-6122
1 MULTI-COMPONENT CUl~TING ELEMENT USING
2 POLYCRYSTALLINE DlAMOND DISKS
4 BACKGROUND OF THE INVENTION
6 l. Field of the Invention
8 The present invention relates to the field of earth
9 boring tools and in particular relates to diamond cutters used on
rotary bits.
11
12 2. ~escription of the Prior Art
14 Rotating diamond drill bits were initially manufactured
with natural diamonds of industrial quality. The diamonds were
16 square, round or of irregular ~hape and fully embedded in a
17 metallic bit body, which was generally fabricated by powder
18 metallurgical techniques. Typically, the natural diamonds were
19 of a small size ranging from various grades of grit to larger
sizes where natural diamonds of 5 or 6 stones per carat were
21 fully embedded in the metal matrix. Because of the small size of
22 ¦ the natural diamonds, it was necessary to fully embed the
23 ~ diamonds within the matrix in order to retain them on the bit
24 face under the tremendous pre-~sures and forces to which a drill
bit is subjected during rock drilling.
26
27 ¦ Later, the commercial production of synthetically
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1 produced dian,ond grit and polycrystalline stones became a
2 reality. For example, synthetic diamond was fiintered into larger
3 disk shapes and were formed as metal compacts, typically forming
4 an amalgam of polycrystalline sintered diamond and cobalt
carbide. Such diamond tables are commercially manufactured by
6 General Electric Company under the trademark STRATAPAX. The
7 diamond tables are bonded, usually within a diamond press to a
8 cobalt carbide slug and sold as an integral slug cutter. The
9 slug cutters are ~hen attached by the drili bit manufacturers to
10¦ a tungsten carbide slug which is fixed within a drill bit body
ll¦ according to the design of the bit manufacturer.
121
13¦ ~owever, such prior art polycrystalline diamond (PCD)
14¦ compact cutting slugs are characterised by a low temperature
15¦ stability. Therefore, their direct incorporation into an
16¦ infiltrated matrix bit body is not practical or possible.
17 l
18¦ In an attempt to manufacture diamond cutting elements of
291 improved hardness, abrasion resistance and temperature stability,
l prior art diamond synthesizers have developed a polycrystalline
21¦ sintered diamond element from which the metallic interstitial
22 components, typically cobalt, carbide and the like, have been
23 leached or otherwise removed. Such leached polycrystalline
24 synthetic diamond is manufactured by the General Electric Company
under the trademark GEOSET, for example 2102 GEOSET5, which are
26 ~ formed in the shape of an equilateral prismatic triangle 4 mm on
27 a side and 2.6 mm deep (3 per carat), and as a 2103 ~EOSET shaped
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1 in the form of an equilateral triangular prismatic element 6 mm
2 on a side and 3.7 mm deep (1 pe~ carat). However, due to present
3 fabrication techniques, in order to leach the synthetic sintered
4 PCD and achieve the improYed temperature stability, it is
necessary that these diamond elements be limited in size.
6 Therefore, whereas the diamor.d compact slug cutters, STRATAPAX,
7 may be formed in the shape of circular disks of 3/8" (9.5 mm) to
8 1/2" (12.7 mm) in diameter, the leached triangular prismatic
9 diamonds, GEOSETS, have maximum dimensions of 4 mm to 6 mm. It
is well established that the cutting rate of a diamond rotating
11 bit is substantially improved by the size of the exposed diamond
12 element available for useful cutting. ~herefore, according to
13 the prior art, the increased temperature stability of leached
14 diamond products has been achieved only at the sacrifice of the
size of the diamond elements and therefore the amount of diamond
16 available in a bit design for useful cutting action.
17
18 What is needed Shen is a PCD cutter which is
19 characterised by the temperature stability and characteristics of
leached diamond products, and yet has the size available for
21 useful cutting action which is characterised by the larger
22 unleached diamond products.
243
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1 ¦ BRIEF SUMMARY OF THE INVENTION
2 l
3 ¦ ~he invention is a cutter for use in a drill bit
4 ~ comprising a plurality of thermally stable PCD disks. A cutting
5 ¦ slug is formed of matrix material and the plurality of diamond
61 disks are disposed in the cutting slug. The matrix material also
71 incorporates diamond grit in at least that portion of the cutting
81 slug in the proximity where the diamond disks are exposed, namely
9l the cutting face o~ the cutter~ By reason of this combination of
10¦ elements, an enlarged cutter is fabricated for mounting within
11¦ the drill bit.
121
13¦ In particular, the invention is a diamond cutter in a
14¦ rotary bit comprising a plurality of circular leached PCD
15¦ prefabricated synthetic disks each having at least one end
16¦ surface. A cutting slug is formed of matrix material and the
171 plurality of PCD disks are disposed àn the cutting slug. The
18 matrix material fills the interstitial spaces between the
19 plurality of PCD disks. The cutting slug is further
characterised by having a cutting face wherein the one end
21 surface of each of the PCD disks is fully exposed on the cutting
22 face. The matrix material, which forms the cutting slug, further
23 comprises and includes diamond grit which is incorporated at
24 ¦ least in that portion of the cutting slug in the proximity of the
25 ¦ cutting face. Preferably, the diamond grit is uniformly
26 ~ dispersed throughout the matrix material. By reason of this
27 ¦ combination of elements, an enlarged diamond table i5 provided as
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1 ¦ a cutter for mounting the rotary bit.
2 l
3 ¦ These and other embodiments of the invention are best
4 ¦ understood by considering the following drawings wherein like
5 elerent are referenced by I ike numerals.
225
26
271
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1 BRIEF DESCRIPI`ION OF THE DRAWINGS
3 Figure 1 is a perspective view of a multicomponent
4 cutting element formed in the shape of a circular disk acsording
to the invention.
7 Figure 2 is a side sectional view of the disk
8 illustrated in Figure 1 shown as attached to a stud cutter.
Figure 3 is a side sectional view of a multicomponent
11 cutting element of the type shown in Figure 1 ~ounted in matrix
12 tooth integrally formed in an infiltrated matrix bit.
13
14 Figure 4 is a perspective view of a second embodiment of
the invention showing a triangular ~haped multicomponent cutting
16 element.
17
18 Figure 5 is a third embodiment of the invention showing
19 a perspective view of a multicomponent rectangular shaped cutting
element.
21
22These and other embodiments can best be understood by
23ewing the above drawings in light of the following deRcription.
267
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1 ¦ DETAILED DESCRIPTION OF THE PRE~ERRED EMBODIMENl'S
2 l
3 ¦ The invention is an enlarged diamond cutter comprised of
4 ¦ a plurality of right circular cylindrical thermally stable
5 ¦ or leached PCD disks arranged in array within a cutting slug or
6 I table. The slug in turn is comprised of metallic powder which is
71 infiltrated, molded or pressed about the array of PCD disks ~o
81 form an amalgamated integral mass. The multiple edges of the PCD
9¦ disks tend to increase the total diamond cutting perimeter.
101
11¦ The invention can better be understood by turning first
12¦ to the illustrated embodLment of Figure 1. In Figure 1 a
13¦ perspective view of a diamond table or cutting slug, generally
14¦ denoted by reference numeral 10, is depicted. Cut~ing slug 10 is
151 comprised of an array of PCD elements 12. In the illustrated
16¦ embodiment, elements 12 are right, circular cylindrical disks
1~¦ which are comprised of leached polycrystalline synthetic diamond
18¦ formed in a diamond press. Such material is of substantially the
1~¦ same composition as synthetic diamond made and sold by ~eneral
201 Electric Company under the trademark GEOSET, or by various
21¦ Ministries of the ~eoples of the People's Republic of China. In
22¦ the case of synthetic diamond material available from China, the
23I diamond stock is sold in rod-like cylindrical shapes of
241 approximately 0.07 inch (2.00 mm) to 0.394 inch (10.0 mm) in
length and 0.078" to 0.315" (2mm to 8mm) in diameter. These
26 rod-like shapes can then be sectioned to form cylindrical disk
27 ¦ eiements 12 to any desired thickness by laser-cutting,
28 l
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1 electrodischarge machining or other equivalent means. For
2 example, in the illustrated embodiment, disk diamond elements 12
3 are 0.157" (4mm) in diameter and 0.039" (lmm) thick.
Cutting slug 10 in the embodiment of Figure 1 has an
6 overall geometric shape of a right circular cylindrical disk. In
7 the illustra~ed embodiment, the thickness of cutting slug 10 is
8 substantially equal to the thickness of diamond elements 12,
9 although it could be increased or decreased if desired. Diamond
10 ¦ elements 12 are disposed in cutting the slug 10 in an array which
11 ¦ may be compactly formed, wherein each diamond element 12 contacts
12 ¦ or is immediately proximate to at least one adjacent diamond
13 ¦ element. PCD elements in the invention in a compact array may
14 ¦ actually touch each other or may be separated by a thin layer of
15 ¦ matrix material which tends to bond the adjacent elements
16 togetbher. For the purposes of this specification, either
17 situation or its equivalent shall be defined as an "immediately
18 proximate" configuration.
Alternatively, the array of diamond elements 12 could be
21 placed within cutting slug 10 in a spaced apart relationship so
22 that no two adjacent elements contacted each other and the
23 interstitial space between diamond elements 12 is completely
24 ~ filled by matrix material 14. ln addition, diamond coverage can
25 I be extended by using fractional portions of whole discs where
26 ~ appropriate. Matrix material 14 is an amalgam of powdered metals
28 ~ well known to the art, principally comprised of tungsten carbide.
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1 Other elements and compounds may be added as well to effect the
2 physical/chemical properties of matrix material 14 a required.
4 The invention is particularly characterised in that
matrix material 14 also incorporates natural or synthetic diamond
6 grit. Any mesh or grit size well known to the art may be used
7 according to the required performance characteristics as
8 determined by well known principles. In general, a grit size of
9 0.01 inch (0.00254 mm) to 0.05 (1,27 mm) inch in diameter is
employed. A diamond grit incorporated or impregnated within
11 matrix material 14 is disposed therein in a dispersion at least
12 within that portion of matrix material 14 forming a layer near
13 ~ cutting face 16 of cutting ~lug 10. In the preferred
14 embodiments, the grit is uniformly distributed throughout the
volume of the matrix material at a concentration of 50~ or more
16 by volume. Cutting face 16 is thus comprised of the exposed end
17 faces 18 of each diamond element 12 and the interstitial exposed
18 ~urface of diamond bearing matrix material 14. In the
19 illustrated embodiment, diamond grit i8 ~ubstantially uniformly
dispersed throughout the entire volume of matrix material 14 and
21 not merely in the proximity of cutting face 16.
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23 Cutting slug 10 of the embodiment of Figure l-may be
24 fabricated by conventional hot pressing or infiltration
techni~ues. Consider fir~t fabrication by hot pressing. A
26 carbon mold, in which a right circular cylindrical cavity is
27 defined, is fabricated with movable end pieces or anvils.
28
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1 Polycrystalline synthetic diamond elements 12, which are
2 prefabricated, typically in a diamond press, are then placed
3 within the cylindrical cavity defined in the carbon mold. The
4 placement may be in a compact array or spaced apart array or such
other arrangement as may be deemed appropriate. Thereafter,
6 powaer metal in which the diamond grit is uniformly mixed is
7 placed in the mold between diamond elements 12 and at least above
8 or below the elements. A greater depth of the diamond bearing
9 matrix powder is loaded in the mold, than the thickness of
10 ¦ diamond elements 12 in order to account for the higher
11 ¦ compressability of the matrix powder as compared to synthetic
12 ¦ polycrystalline diamonds 12. Sealing anvils are then placed on
13 ¦ the top or bottom or both ends of the cylindrical cavity of the
14 ¦ filled carbon mold and the mold and anvils are then placed within
15 ¦ a hot press. The filled mold and its contents are then heated by
16 a conventional induction heater and subjected to pressure. The
17 pressure and temperature causes the matrix powder to amalgamate
18 and compress to form the circular disk depicted as cutting 81ug
19 10 in Figure 1. The pressures and temperatures used in the hot
press are well outside the diamond synthesis phase regions and no
21 appreciable amount of diamond is either synthesized or converted
22 into graphite during the process. Por example, a pressure of
23 200 psi is exerted upon the contents of the filled mold which is
24 held at 1900 F for 3 minutes. The result is a multi-component
25 ¦ array of PCD elements 12 in a circular cylindrical disk 10 of
26 ¦ approximately 0.512~ (13mm) in diameter.
27
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1 The same disk may be fabricated by conventional
2 infiltration techniques wherein diamond elements 12 are again set
3 within a carbon mold which is backfilled with matrlx powder. The
4 filled mold is then pressed and the powder allowed to ~ettle and
infiltrate to form an amalgamated sintered mass having the shape
6 as defined by the mold.
8 Turn now to Figure 2 wherein cutting slug 10 is shown in
9 sectional side view. Cutting slug 10 may be bonded by soldering
or brazing to a steel or tungsten carbide stud 20 well known to
11 the art. Stud 20 in turn is disposed within a drill bit body by
12 press fitting, brazing or other well known methods. Cutting slug
13 10 in the illustrated embodiment is bonded to stud 20 by braze or
14 solder forming a bonding layer 22 hown in exaggerated sectional
view in Figure 2. Cutting face 16 is thus fully exposed and
16 provides the useful cutting surface. Therefore, by using high
17 temperature-stable and improved leached diamond elements 12, an
18 enlarged cutting slug 10 of a size comparable or greater than
19 presently available diamond compact cutters, such as STRATAPAX
cutters, can be employed in conventional bit designs or in
21 combination with conventional stud cutters as illustrated in
22 Figure 2.
23
24 Figure 3 shows a side sectional view of cutting slug 10
as disposed within an infiltrated matrix body bit. Only the
26 tooth portion of the matrix body is illustrated. Cutting slug 10
227 ~ is disp ed in a carbon ~old according to conventional
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1 infiltration techniques. Thereafter, the mold is filled with a
2 metal matrix. The filled mold is then furnaced allowing the
3 metallic powder to become sintered and infiltrate downward
4 through the mold to form an integral mass. As illustrated in
Figure 3, cutting slug 10 thus becomes bonded to the integral
6 mass of the matrix body and is embedded therein according to the
7 bit design and tooth structure defined within the mold. For
8 example, in the illustrated embodiment of Figure 3, cutting slug
9 10 is fully exposed above surface 24 of the bit and is provided
10¦ with a trailing, integrally formed portion 26 to provide a
11 ¦ backing and ~upport for cuttin~ slug 10. Cutting face 16 thus is
12 ¦ fully exposed and forms the forward moving surface of the
13 ¦ composite tooth structure that i~ characterised by an overall
14 ¦ size and geometric shape heretofore characterised only by diamond
15 ¦ compact stud cutters which could not be fabricated within an
16 ¦ infiltration matrix bit because of their poor thermal stability.
17 l
18 Turn now to the second embodiment of Figure 4 wherein a
19 cutting slug, generally denoted by reference numeral 28, is
O formed in the shape of a ~riagular table. Again, a plurality of
21 synthetic PCD right circular disks 12 are disposed within cutting
22 ~lug 28. Diamond elements 12 are disposed in an array which may
23 either be compactly formed or spaced-apar~. The interstitial
24 ¦ space between and about diamond elements 12 within cutting slug
25 ¦ 28 is comprised of a metallic diamond bearing matrix 14 described
27 ¦ above. As before, diamond elements 12 have at least one circular
28 end face exposed on cutting face 3~ of cutting slug ~8. The
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1 thickness of slugs 28 may be substantially equal to the thickness
2 of diamond elements 12. Again, cutting slug 2B may be formed by
3 conventional hot press or infiltration techniques and then
4 mounted on a stud in the manner as shown in connection with
~igure 2 or airectly disposed within an infiltrated matrix body
6 bit as described in connection with Figure 3.
8 Figure 5 illustrates a third embodiment of the invention
9 wherein a diamond table or cutting slug, generally denoted by a
reference numeral 32, is formed in a rectangular or square shape.
11 The same circular diamond elements 12 as described above are
12 disposed within cutting slug 32 in an array with the interstitial
13 spaces between and around diamond elements 12 filled with a
14 diamond bearing matrix material 14. The embodiment of Figure S
differs only from that of Figure 4 and Figure l by the overall
16 gross geometric outline of the cutting slug and not by any detail
17 of its constituents or mode of fabrication~ Again, the cutting
18 Elug is fabricated using infiltration or hot press technigues and
19 can then be mounted on a stud cutter in the manner briefly
described in Figure 2 or directly in a matrix bit as suggesteà in
21 Figure 3.
22
23 Many alterations and modifications may be made by those
24 having ordinary skill in the art without departing from the
spirit and scope of the invention. The illustrated embodiment
26 has been shown only for the purposes of clarity and example and
27 should not be taken as limiting the invention which is defined in
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2 he f ol low ing cl a ims .
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