CA1245625A - Multi-component cutting element using consolidated rod-like polycrystalline diamond - Google Patents

Abstract

MULTI-COMPONENT CUTTING ELEMENT USING
CONSOLIDATED ROD-LIKE POLYCRYSTALLINE DIAMOND

ABSTRACT OF THE DISCLOSURE
An enlarged diamond table for use as a cutter in rotating drill bits is provided by disposing a plurality of thermally stable or leached polycrystalline diamond (PCD) rod-like elements within a matrix body. In one embodiment the matrix body is impregnated with diamond grit and completely fills the interstitial spaces between the plurality of PCD elements.
Generally, the PCD elements have their longitudinal axes arranged in a mutually parallel configuration. The bundle of rod-like diamond elements are in one embodiment in a compact touching array and in another embodiment in a spaced-apart array. In the illustrated embodiment, a bundle of rod-like diamond elements are disposed so that their end surfaces are exposed on the cutting face of the cutting slug. The slug is then in turn mounted on a stud or directly infiltrated into a matrix body bit.

Description

~ 5

2 CONSOLIDATED ROD-LIKE POLYCRYSTALLINE DIAMOND

4 BACKS;ROUND OF THE INVENTION

6 1~ Fieid 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 rotating bits.

12 2. Description 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 shape 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 pressures and forces to which a drill bit is subjected during rock drilling.

27 Later, the commercial production of synthetically l ~ 5~5 1 roduced di~mond grit and polycry~t~lline stonec became a 2 ¦ reality. For example, synthetic diamond was sintered into larger

3 1 disk shapes and were formed as metal compacts, typically forming

4 ¦ an amalgam of polycrystalline sintered diamond and cobalt

5 ¦ 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 then attached by the drill bit manufacturers to

10 1 a tungsten carbide slug which is fixed within a drill bit body ll ¦ according to the design of the bit manufacturer.

13 ¦ ~owever, CUch prior art polycrystalline diamond (PCD~
14 ¦ compact cutting slugs are characterised by a low temperature ~tabili~y. Therefore, their direct incorporation into an 16 infiltrated matrix bit body is not practical or possible at this 17 time.

19 In an attempt to manufacture diamond cutting elements of improved hardness, abr~sion resistance and temperature stability, 21 prior art diamond synthesizers have developed a polycrystalline 22 sintered diamond element from which the metallic inters~itial 23 components, typically cobalt, carbide and the like, have been 24 leached or otherwise removed. Such leached polycrystalline synthetic diamond is manufactured by the General Electric Company 26 under the trademark GEOSET, for example 2102 GEOSETS, which are 27 formed in the shape of an equilateral pri~matic triangle 4 mm on 2~

~ 456'~S

1 a side and 2.6 mm deep (3 per carat), and as a 2103 GEOSET shaped 2 in the form o~ an equilateral triangular pri~matic element 6 mm 3 on a side and 3.7 mm deep (1 per carat). ~owever, due to present 4 fabrication techniques, in order to leach the 6ynthetic 6intered PCD and achieve the improved ~emperature stability, it is 6 necessary that these diamond elements be limited in size.
7 Therefore, whereas the diamond compact slug cutters, STRATAPAX, 8 may be formed in the ghape of circular disks of 3/8" (9.5 mm) to 9 1/2~ (12.7 mm) in diameter, the leached triangular prismatic diamonds, GEOSETS, have maximum dimensions of 4 mm to 6 mm. It

11 is well established that at least in soft formations

12 the cutting rate of a diamond rotating bit is substantially

13 improved by the size of the exposed diamond element available or

14 useful cutting. ~herefore, according to the prior art, the increased temperature ~tability of leached diamond products has 16 been achieved only at the sacrifice of the size of the diamond 17 elements and therefore the amount of diamond available in a bit 18 design for useful cutting action.

What is needed then is a PCD cutter which is 21 characterised by the temperature stability and characteristics of 22 leached diamond products, and yet has the cize available for 23 useful cutting action which is characterised by the larger unleached diamond products.

1;2D~5625 3 The invention is a diamond cutting element for use in a 4 drill bit comprising a plurality of thermally stable PCD cutting elements wherein each element is characterised by having a 6 longitudinal axis. A cutting slug is formed of matrix material.
7 The plurality of PCD elements are disposed in the matrix material 8 so that their longitudinal axes are generally mutually parallel.
9 Furthermore, tbe matrix material forming the cutting slug may incorporate diamond grit dispersed at least through a portion 11 of the cutting slug near the exposed end of the slug or its 12 cutting face. By reason of this combination of elements, an 13 enlarged diamond cu~ting 81ug can be provided for mounting within 14 the drill bit.

16 More particularly, the invention is a diamond cutter for 17 ufie in a drill bit. The diamond cutter comprises a plurality of 18 leached PCD elements each of which are characterised by having a 19 longitudinal axis. ~he PCD elements are arranged and configured in the cutter so that their longitudinal axes are mutually 21 parallel. Diamond bearing matrix material is disposed between 22 the plurality of PCD elements to form an aggregate cutting slug 23 of a predetermined gross shape. By reason of this combination of 24 elements, an enlarged diamond cu~ter having a geometric size of unleached diamond product is provided and is substantially 26 characterised by haviny the physical or material properties of 27 the plurality of leached PCD elements.

I 1~456'~ ' 1 ¦ The invention includes a diamond cutter element for use 2 in a drill bit comprising a plurality of thermally stable 3 polycrystalline diamond cutting elements wherein each cutting 4 element is characterized by a longitudinal axis. The diamond cutter element also includes a matrix material forming a cutting 6 slug. The plurality of PCD elements are disposed in the matrix 7 material so that the longitudinal axes of each of the elements 8 are generally mutually parallel. The cutting slug is disposed in 9 the drill biit to present the longitudinal axes of the plurality of PCD cutting elements in a predetermined direction. The ll cutting slug is characterized by a cutting direction and ~he 12 cuttiny direction is defined as the instantaneous direction of 13 the linear displacement of the cutting ælug as determined by the 14 drill bit when the drill bit is operative, typically rotating.
In general, the predetermined direction may be parallel, 16 perpendicular, or inclined with respect to the cutting direction 17 and each PCD cutting element i6 characterized by having a 18 needle-like ~hape.

The invention is illustrated in the following Figures 21 ~herein l1ke elements are referenced by llke numerals.

~ zs 3 Figure 1 is a perspective view of a diamond cutter 4 utilizing cylindrical rod-like PCD pieces.

6 Figure 2 is a perspective view of a second embodiment 7 of a cutter wherein a pluralitiy of guarter-split cylinders are 9 employed.

Figure 3 is a perspective view of a third embodiment of 11 a cutter wherein a plurality of rectangular rod-like diamond 23 elements are employed.

14 Figure 4 is an end view of a fourth embodiment of a cutter wherein a plurality of elliptically shaped diamond rods 16 are employed.

1 Figure 5 is perspective view of a fifth embodiment in 19 the form of a triangular prismatic cutter utilizinq a plurality 22 f circular diamond rods of the type generally shown in Figure 1.

22 Figure 6 is a perspective view of a sixth embodiment 23 wherein a prismatic, rectangular cutting element is provided 2 which utilizes a plurality of circular diamond rod pieces.

2 Figure 7 is an end view of a seven~h embodiment in the 2 form of an elliptically shaped prismatic cutter wherein a 1~6~:5 1 plurality of cylindrical diamond pieces are employed.

3 Figure 8 is a perspective view of a stud cutter 4 employing the cutter shown in Figure 1.

6 Figure 9 is a side view of an infiltrated cutting tooth 7 using the cutter shown in ~igure 1, wherein the cutter is 8 generally oriented parallel to the bit face.

Figure 10 is a cross-sectional side view of an 11 infiltrated cutting tooth using the cutter shown in Figure 1, 12 wherein the ~utter is generally perpendicularly oriented with 13 respect to the bit face.

Figure 11 is a cross-sectional side view of an 16 infiltrated cutting tooth using the cutter shown in Figure 1, 17 wherein the cutter iB generally oriented at an angle with respect 18 to the bit face.

Figure 12 is a perspective view of a cutter wherein a 21 plurality of PCD rods are transversely oriented with respect to a 22 longitudinal axis of the cutter.

241 Figure 13 is a perspective view of a cutter wherein the 251 PDC rods are oriented at an angle with respect to the 27 longitudinal axes of the cylindrical cutter.

, I -B-I ~L~45~5 l~ Figure 14 is s perspective viev of a cylindrica1 cutter 2 ~ wherein the PCD elements are oriented diamond needles.

4 ¦ Figure 15 is a perspective view of a generally ¦ rectangular cutter wherein the PCD elements are oriented diamonds 6 ¦ needles.

8 ¦ The various embodiments of the invention can be better 9 ¦ understood by considering the above Figures in light of the iollowing etailed description.

22s _g_ ~4~ ,5 1 DETAILED DESCRIPTION OF T~E PRE~ERRED EMBODIMENT

3 The invention is an improved PCD cutter made of a 4 composite of thermally stable or leached rod-like diamond elements wherein the elements are combined to form an enlarged 6 cutter body, and are bound together by a metallic matrix to form 7 an enlarged, exposed diamond cutting surface~ The multiple edges 8 of the PCD elements tend to increase the total effective cutting 9 perimeter.

11 Consider first the embodiment of Pigure l. A cutter 12 body, generally denoted by reference numeral lO, i6 compri~ed of 13 a plurality of diamond cutting elements 12. Diamond autting 14 elements 12, in the preferred embodiment are each in the form of right circular cylinder having a diameter of approximately 0.25~
16 to 0.75u ana a height of approximately 0.078 inch (1.98 mm) to 17 0.394 inch (lO.O mm). Althou~h such cylindrical rod-like diamond 18 elements are generally in the form of a right circular cylinder, 19 one end of the cylinder i8 formed as a flat perpendicular ~urface while the opposing end is formed an axially symmetric dome or 21 conical shape of approximately 0.039-0.118 inch (1-3 mm) in 22 height depending on the size of the cylinder and manufacturing 23 variations. For example, dome topped PCD cylinders of the 24 following diameters and lengths respectively are presently commercially available: 2mm diameter by 3mmm long; 4mm by 6 mm;
26 6mm by 6mm; 6mm by 8mm; and 8mm by lOmm. The shape and pro-27 portions of each vary depending on gross geometries and minor '.~ . I

~X~5~25 1 process variations.

In the illustrated embodiment of Figure 1, cutter 10 is 4 ~hown in perspective view with a cutting face 14 facing the viewer. The PCD elements 12 as described above may be oriented 6 within cutting slug 10 with the axial ends of cylinders 12 7 generally coplanar with face 14. In other words, each of the 8 plurality of rod-like cylindrical diamond elements 12 are 9 disposed with their axis of symmetry generally parallel to the axis of ~ymmetry of cylindrical cutting slug 10. Further, each 11 of the diamond elements 12 is of approximately identical chape 12 and size so that when bundled to form cutting slug 10, one axial 13 end of each cylindrical element 12 can be aligned with the 14 corresponding ends of each of the other cylindrical elements in the bundle to form a generally flat face 1~. Either the flat or 16 domed end or both of cylindrical elements 12 may be oriented on 17 face 14.

19 Therefore, a~ shown in the illustrated embodiment of Figure 1, face 14 of cutting slug 10 forms a generally circular 21 surface. Inasmuch as cylindrical diamond elements 12 are also 22 circular in cross section, the interstitial space between 23 cylindrical diamond elements 12 throughout cutting slug 10 is 24 filled with a metallic matrix 16. The compo~ition of matrix 16 may be chosen from powder mixtures well known in the art as 26 presently used for the fabrication of powder metallurgical 28 infiltration bits. Generally, such metallic matrices 16 are 11'-~ ~,245~25 1 ¦ tungsten carbide sintered mixtures containing selected amounts of 2 ¦ various other elements and compounds as are well known in the art 3 ¦ to achieve the desired body characteristics.
4 l 5 ¦ According to the present invention, matrix 16 within 6 ¦ cutting slug 10 is impregnated with natural or synthetic diamond 7 ¦ grit, thereby substantially improving the abrasive resistant 8 ¦ qualitie6 of matrix 16. The grit i~ disposed within cutting slug 9 ¦ 10 at least within the proximity of the cutting face, and 10 ¦ preferably uniformly throughout its volume. Again, the mesh or 11 ¦ ~ize of diamond grit included within ~atrix 16 between rod-like 12 ¦ diamond elements 12 can be selected according to ~ell kn~wn 13 ¦ principles to obtain the desired abrasive result6. Generally, 14 ¦ the diameter of 6uch grit varies between 0.010 inch (0.00254 mm)

15 ¦ to 0.05 inch (1.27 mm). A grit concentration of 50~ or more by

16 ¦ volume is preferred.

17

18 Consider now slug 10 of the embodiment of Figure 1.

19 Slug 10 can be fabricated either by conventional infiltration or hot pressing techniques. Consider, for example, the fabrication 21 according to hot pressing techniques. A plurality of cylindrical 22 diamond rods 12 are arranged in a hot press mold either in the 23 compact touching configuration as shown in Figure 1 or in a 24 spaced-apart configuration similar to that described in connection with the below described embodiments of the invention.
26 Selected ~atrix powder 16 is similarly loaded into the mold 27 between the interstitial areas between cylinders 12 as well as ~ abo~e r below the bundle cylinders by amount taking into 2 ¦ consideration the greater compressibility oP the material of 3 I matrix 16 as compared with that of synthetic diamond of rods 12.
4 ¦ Typically, such mold parts are made of graphite and are then 5 ¦ placed within a conventional hot press. The mold and its 6 ¦ contents are then heated, usually by a conventional induction 7 ~ heater, and subject to pressure. The pressures and temperatures 8 I used to form cutting slug 10 are well outside of the diamond 9 ¦ synthesis phase regions and result in a compact sintered matrix 10 ¦ mass in which rods 12 are securely embedded as depicted in Figure 11 1. For example, a pressure of approximately 200 psi and a 12 temparture of 1900F exerted and held on a cylindrical mold 13 holding a cylindrical bundle of diamond elements 12 for a period 14 of 3 minutes produces 61ug cutter 10 as depicted in Figure 1. It is understood, of course, that many other temperatures, pressures 16 and holding times could be equivalently employed without 17 departing from the spirit and scope of the invention.

19 Turn now to the second embodiment o~ Figure 2 wherein a perspective view of a right clrcular cylindrical cutting slug 18 21 is depicted. In contrast to the first embodiment of Figure 1, 22 the embodiment of Figure 2 incorporates a plurality of split 23 cylindrical diamond elements 20 embedded within an interstitial 24 diamond bearing metallic matrix 16. In the illustrated embodiment, rod-like PCD elements 20 are comprised of 26 quarter-split cylindrical element6. In other words, the right 27 circular cylindrical elements 12 described in connection with ~s~z~

1 Figure 1 are sectioned into quarters to form quarter-split 2 cylinders. Such section can be accomplished by laser cutting, 3 electrodischarge machining or other equivalent means. Split 4 cylindrical elements 20 may then be arranged in a spaced-apart pattern as depicted in Figure 2, each with its apical point 24 6 oriented in the same direction as shown, oriented in radial 7 directions, alternating in reversed directions or other 8 convenient patterns as may be chosen. Again, the interstitial 9 matrix material 16 incorpsrates a diamond grit to prevent the erosion of matrix 16 from between elements 20 while cu~ting slug 11 18 is subjective to the abrasive wear of rock and hydraulic fluid 12 in a drill bit.

14 Again, cutting 81ug 18 of Figure 2 may be fabricated by conventional hot pressing or infiltration techniques as 16 described. Consider now fabrication by an infiltration 17 technique. Elements 20 are disposed in a generally parallel, 18 spaced apart bundle, with the longitidinal axis of each rod-like 19 cutter 20 generally parallel and 6paced apart from the longitudinal axis of the adjacent rod-like element6 20. The 21 axial ends of elements 20 are similarly aligned to provide a 22 generally flat cutting face 26. Rods 20 are placed within a 23 predetermined location within a machined carbon mold, typically 24 by gluing in the same manner as natural or syn~hetic single piece diamonds are placed within infiltration molds. Thereafter, 26 powdered matrix material i5 filled within the mold and tapped or 27 vibrated, thereby causing it to settle in place within the mold.
~8 ~ 6~5 1 Diamond elements 20 will then be surrounded by matrix powder.
2 Thereafter the fill mold is furnaced, causing the matrix material 3 to melt and infiltrate downwardly and throughout the mold cavity 4 resulting in the embedded structure as shown in Figure 2, and as better shown and described in connection with ~igure 9. For the 6 sake of clarity, the depiction of Figure 2 shows cutter 18 apart 7 from any bit body which may be integrally formed therewith.

9 Alternatively, cutting slug 18 may be separately fabricated by an infiltration technique apart from a bit mold. A
11 carbon mold defining the shape and size of cutting slug 18 is 12 provided and a plurality of split cylindrical rod elements 20 13 disposed and fixed within the carbon mold as before by gluing.
14 Thereafter, the interstitial spaces between elements 20 is filled within a selected diamond impregnated matrix material. The 16 carbon mold for cutting slug 18 is thereafter furnaced to allow 17 the matrix material ~o become sintered and infiltrate between 18 elements 20. The body is cooled and the finished slug removed 19 from the mold. Thereafter, tbe infiltrated slug can be handled as a single element and placed as described in greater de~ail in 21 connection with Figures 8 and 9 within a bit body~
22 l 23 I Turn now to Figure 3 wherein the ~hird embodiment of the 24 invention is illustrated. Whereas the first and second embodiments of Figures 1 and 2 respectively 6howed a plurality of 26 right circular cylindrical or split cylindrical rod elements, the 2~3 tl i rd embod iment of Pi gu r e 3 i 11 ust r a tes the embod imer t whe r e i r~ a ~ 56'~5 1 plurality of rectangular or square rod-like elements 28 are 2 incorporated within a cutting slug 30. Once again, PCD elements 3 28 may be placed within cutting slug 30 ~n a compacted 4 arrangement or in a spaced apart arrangement where in the interstitial metal matrix in either case forms a diamond bearing 6 body. As before, cutting slug 30 is shown as a right circular 7 cylinder and may be formed by conventional hot pressing or 8 infiltration techniques as described above.

Figure 4 represents yet a fourth embodiment of the 11 invention wherein a right circular cylindrical cutting slug 32 12 employs a plurality of elliptically ~haped rod-like elements 34.
13 In other words, the cross ~ection of elements 34 are generally 14 noncircular or elliptical and are aligned within cutting slug 32 80 that their longitudinal axes are generally parallel.
16 Elliptical elements 34 may be arranged within cutting slug 32 in 17 a spaced apart relationship or in a more compacted form wherein 18 each element touches or is immediately proximate to adjacent 19 elements. Again, the lnterstitial material between elements 34 is comprised of a diamond bearing metallic matrix, and the 21 aggregate body comprising cutting slus 32 is fabricated by hot 22 pressing or infiltration. PCD elements in the invention in a 23 compact array may actually touch each other or may be separated 24 by a thin layer of matrix material which tends to bond the adjacent elements together. For the purposes of this specification, either situation or its equivalent chall be 28 defined as an ~immedia~ely proximate~ configuration.

1245~i25 1 A fifth embodiment is illustrated in Figure 5. Cutting 2 ~lug 36 of Figure 5 employs the same right circular cylindrical 3 cutting elements 12 of the embodiment of Figure 1 but aggregates 4 elements 12 in a bundle or spaced-apart relationship so that the gross overall outline of cutting slug 36 is generally triangular 6 and prismatic. Interstitial areas between elements 12 of cutting 7 slug 36 are again filled with a diamond bearing matrix 16 by hot 8 pressing or infiltration.

A variation of overall slug cutter shapes are also shown 11 in the sixth and seventh embodiments of Figures 6 and 7 12 respectively. In the case of Figure 6, risht circular 13 cylindrical elements 12 are shown in perspective view as bundled 14 within a generally rectangular or square cutting slug 40.
Rod-like elements 20 are combined either in a compacted and 16 touching bundle or in a spaced-apart relationship wherein the 17 interstitial spaces are again filled with diamond bearing matrix.
18 In the embodiment of Figure 7, an end view is ~llu~trated showing 19 right circular cylindrical rod-like elements 12 once again aggregated within an elliptically shaped cutting slug 42 bound 21 together in diamond bearing matrix material 16.

23 Clearly, the various embodiments shown and described in 24 connection with Figures 1-7 are set forth purely for the purposes of example and should not be taken as limiting the spirit or 26 scope of the invention. The overall geometric shape formed by 227 the cutting slugs in each case may be chosen according to the !

1 ~45~

1 optimal design and utility of the bit and c~mbined with any one 2 of a plurality of shapes of rod-like PCD elements arranged as 3 ¦ compacted or spaced-apart bundles as shown. The combinations 4 ¦ explicitly illustrated are the preferred combinations but by no 5 ¦ mèans exhaust the logical combinations which could be produced 6 ¦ between overall gross outline and constituent diamond rod-like 7 elements which can be used according to the invention to form an 8 enlarged diamond cutter. In addition to variations in shapes and 9 sizes as just described, the number of cutting elements included with any chosen 81ug can also be varied according to the desired 11 ¦ result.

13 ¦ Turn now to Figure 8 wherein a cutting slug of the 14 ¦ invention is shown as mounted on a stud for insertion within a bit body. In the illustrated embodiment of Figure 8 the first 16 embodiment of cutting slug 10 is utilized. Cutting slug 10, with 17 cutting face 14 outwardly disposed, is raised onto a tungsten 18 ¦ carbide stud 46. Such studs 46 are well known to the art and 19 ¦ many designs have been developed for use in connection with

20 ¦ diamond contact tables. Thus, as depicted in Figure 8, cutting

21 ¦ slug 10 is bonded to tungsten carbide stud 46 by a brazed layer

22 ¦ 48 shown in exaggerated thickness. The longitudinal axes of each

23 ¦ rod~like cutting element 12 within cutting slug 10 is arranged

24 within cutting slug 10 so a~ to be generally parallel to the longitudinal axis of symmetry 50 of the 81ug 10. Axis 50 as 26 illu~trated in Figure 8 is approximately normal to cutting face 27 14. Stud 46 is then press fit, brazed and otherwise inserted by ~2~i25 1 conventional means into a bit body (not shown) 80 that face 14 is 2 disposed so that axis 50 is oriented in a generally azim~thal or 3 advancing direction as defined by the rotation of the rotating 4 bit.

6 Turn now to Figure 9 wherein the utilization of cutting 7 slug 10 is shown in an alternative embodiment in an infiltration 8 bit. Cutting 61ug 10 is shown in diagrammatic 6ectional side 9 view as being directly infiltrated into a matrix body generally denoted by a reference numeral 52. Once again, cylindrical 11 elements 12 within cutting slug 10 are arranged B0 that their 12 longitudinal axes are generally parallel to longitudinal axis 50 13 normal to cutting face 14. Body 52 forms a pocket about cutting 14 slug 10 thereby providing both basal and backing support as diagrammatically depicted by a trailing upport portion 54 16 integral with body 52 of the infiltration bit. The cutting tooth 17 configuration of Figure 9 is fabricated according to conventional 18 infiltration techniques as described ~bove. In other words, 29 cutting ~lugs 10 are placed in predetermlned positions within the O carbon mold with a metallic powder filled behind slugs 10.
21 Thereafter, tbe filled mold is furnaced, the metallic powder 22 melts and infiltrates to form a solidified mass in which cutting 23 slugs 10 are embedded.

Although in each of the illustrated embodiments rod-like 26 elements 12, ?o, 28 and 34 have been shown as having their 28 longitudinal axes each aligned to be generally parallel to a j ~ 6~5 1 ¦ corresponding longitudinal axis of a corresponding cutting slug, 2 ¦ it is entirely within the scope of the invention that such 3 ¦ diamond elements may be arranged in bundles or in spaced-apart 4 ¦ groups so that the axes of each are inclined at predetermined 5 ¦ angles with respect to a selected axis of symmetry of the cutting 6 ¦ slug. In the extreme, it may be poss.ible for the diamond 71 rod-like elements to be arranged and oriented along a direction 8 ¦ substantially perpendicular to the normal of the cutting face, 9 ¦ such as would be achieved by rotating cutting slug 40 of the 10¦ embodiment of Figure 6 80 that cutting face of cutting slug 40 11 ¦ was not face 56, as shown in Figure 6, but an adjacent side, ~uch 12¦ as face 58.

14 ¦ Figures 10-13 illustrate such additional embodiments.
15¦ Figure 10, for example, shows the cutter of Figure 1 wherein 16 ~ cylindrical body 10 is oriented with respect bit face 60 is 171 generally perpendicular orientation. Cylindrical rod-like PC~ 16 18 ¦ are again oriented generally parallel to the longitudinal axis of 19¦ cylindrical cutter 10. ~owever, cutter 10 has been disposed 201 above, on or in bit face 60 of a matrix drill bit accordingly to 21 ¦ conventional infiltration fabrication techniques 60 that PCDs 16 22 ¦ are generally perpendicular to the direction of cutter travel.

24 ¦ Figure 11 is a cross-sectional view of another

25 ¦ embodiment of cutter 10 of Figure 1, wherein cutter 10 is

26 ~ disposed above, on or in bit face 60 in an angular orient~tion so

27 ¦ that PCD rods 16 are acutely or obli~uely aligned with respect to ~8 I

~ 25 1 the direction of travel or advance of cutter 10 as the bit i8 2 rotated.

4 Figure 12 illustrates a cutter, generally denoted by reference remo~e 62, wherein rod-like PCD elements 12 are 6 transversely disposed within cylindrical cutter 62. Each PCD 12 7 is oriented within cutter 62 in a direction substantially 8 perpendicular to its longitudinal axis 64. Certain ones of PCD
9 elements 12 may lie on or near longitudinal ~xis 64, and thus have a length substantially equal to the full diameter of cutter 11 62. Other ones of PCD elements 12 lie well off longitudinal axis 12 64, and thus have a length determined by the cord segment across 13 which cylindrical PCD element 12 i~ disposed within cylindrical 14 cutter 62. The spacing or density of PCD elements 12 within cutter 62 is chosen according to the nature of the rock formation 16 for which cutter 62 is intended. For example, although shown in 17 the illustrated embodiment of Figure 12 as a l~osely ~paced 18 array, it is entirely within the scope of the invention that the 19 array of PCD elements 12 may be densely packed in the touching arrangement such as shown in the cutters of Figures 1, 5 and 6.

22 Turn now to Figure 13, where yet ano~her embodiment of 23 the invention is illustrated in connection with a cylindrical 24 cutter generally denoted by reference numeral 66. Cutter 66 has the ~ame overall gross cylindrical geometry as cutter 62 in 26 Figure 12 with the exception that rod-like PCD elements 12 are 27 disposed within cutter 66 at a bias or at an angle with respect ~ rj 1 to longitudinal axis 6B. In the embodiment of Figure 13, each 2 ¦ rodlike PCD element 12 is disposed in a predetermined direction 3 ¦ at various distances offset from longitudinal axis 68. Thus, 4 ¦ biased PCD elements 12 of Figure 13 form an nrray of elements 5 ¦ offset from longitudinal axis 68, with the length of each element 6 ¦ being determined by its position in the array relative to the 71 cylindrical ~urface of cutter 66. It must be understood with 81 respect to the embodiment of Figure 13, just as with those shown 9¦ in Figures 10-12, that whereas in the illustrated embodiment 10¦ elements 12 are shown spaced apart, it is entirely consistent 11 with the invention that a densely packed array could be 12 ~ubstituted.

14 Turning now to Figure 14, a larger disclike cutter, generally denoted by reference numeral 70 is illustrated, wherein 16 cutter 70 has disposed therein a multiplicity of needle-shaped 17 PCD elements 72. For the sake of clarity of Figure 14, only a 18 ¦ portion of such needle elements are illustrated, and it is 19¦ contemplated that the entire volume of cutter 70 will be filled 201 with an array of such elements 72. ~eedle-like elements 72 are 21¦ much like rod-like PCD elements 12 shown in connection with the 22 ¦ embodiments of Figures 1-13~ with the exception that needle-like 231 elements 72 have a much smaller diameter. Whereas the smallest 241 rod-like PCD element 12 now commercially ~vailable measures 251 approximately 2 mm in diameter, needle-like elements 72 have a 26¦ diameter substantially less than 2 mm. The detailed confis-27 1 uration of the ~ I -22^

~562~ ~

1 array of needle-like PCD elements 72 within disc cutter 70 can be 2 varied according to the overall cutting and abrasive-wear 3 resistance desired. For example, in the less abrasive formations 4 a space-apart array~ such as that suggested in Figure 14, may be employed. The array may be arranged in concentric circles of 6 needle-like elements 72, wherein elements 72 between each circle 7 may or may not be as azimuthally offset from the adjacent 8 circular row. Additionally, needle-like element~ 72 may be 9 compactly disposed within the metal matrix of cutter 70, either according to a regular geometric packing, or in a randomly packed 11 arrangement. Furthermore, although needle-like elements 72 have 12 been ~hown as each disposed in a direction generally parallel to 13 the longitudinal axis of symmetry of disc-like cutter 70, other 14 orientations of elements 72 within cutter 70, similar to that shown in Figures 12 and 13, may also be utilized.

17 Similarly, turning to Figure 15, needle-like elements 72 18 may be disposed in cutters of dramatically different geometric 19 configurations, such as cutter 74 of Figure 15. Cutter 74 of Figure 15 is generally a rectangular shaped or block-shaped 21 cutter wherein needle-like elements 72 are disposed, again shown 22 in the illustrated view for the sake of clarity only in a 23 partially depicted perspective view. In other words, al~hough 24 Figure 15 illustrates only certain portions of cutter 74 having 25 ¦ elements 72, it is contemplated ~hat the entire volume of cutter 26 ¦ 74 i8 filled with or has elements 72 disposed therein. As in the ?8 case of cutter 70 of Figure 14, cutter 74 of Figure 15 may employ ~24~6~5 1 needle-like PCD elements with varying angles of disposition as 2 described above. For example, rod-like PCD elements 12 of cutter 3 66 of Figure 13 may be replaced by a plurality of needle-like 4 elements 72. Cutter 66 is then disposed in or on a bit face with its longitudinal axis 68 generally parallel to the cutting 6 direction. ~iased needles 72 replacing rods 12 would then wear 7 or fracture during cutting one needle at a time so that loss of 8 diamond material due to fracturing during cutting is 9 substantially limited.

11 Therefore, it must be understood that many modifications 12 and alterations may be made by those having ordinary skill in the 13 art without departing from the cpirit and scope of the ~nvention.
14 The illustrated embodiment has been ~hown only for the purposes of example and clarification and should not be taken as limiting 16 e 1nvention which i9 defined further in the following cl9im9.

2C~

28

Claims (26)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS.

1. A diamond cutter element for use in a drill bit comprising:
a plurality of thermally stable polycrystalline diamond cutting elements each characterised by a long-itudinal axis; and a diamond table formed of a matrix material, said plurality of polycrystalline diamond elements disposed in said matrix material wherein said longitudinal axis of said elements are generally mutually parallel, whereby an enlarged diamond table can be provided for mounting within said drill bit.

2. The cutter of Claim 1 wherein said matrix material incorporates diamond grit dispersed at least through a portion of said diamond table.

3. The cutter of Claim 1 wherein said polycrystalline diamond elements are each comprised of right circular cylindrical synthetic diamond rods.

4. The cutter of Claim 1 wherein said polycrystal-line diamond elements are each comprised of a longitudinal segment of a right circular cylindrical rod.

5. The cutter of Claim 4 wherein said longitudinal segment is a quarter-split cylindrical rod.

6. The cutter of Claim 1 wherein said polycrystal-line diamond elements each comprise a generally rectangular prismatic rod.

7. The cutter of Claim 1 wherein said polycrystal-line diamond elements each comprise a generally elliptical rod.

8. The cutter of Claim 1 wherein said matrix material forms said diamond table generally in the form of a right circular, cylindrical disk.

9. The cutter of Claim 1 wherein said matrix material forms said diamond table in the shape of a generally tri-angular prismatic section.

10. The cutter of Claim 1 wherein said matrix material forms said diamond table generally in the shape of a rectangular prismatic section.

11. The cutter of Claim 1 wherein said matrix material forms said diamond table generally in the shape of an el-liptical disk.

12. The cutter of Claim 1 wherein said diamond table formed of matrix material is further characterised by having an axis of symmetry and wherein each of said polycrystalline diamond elements has its longitudinal axis arranged and configured generally parallel to said axis of symmetry of said diamond table.

13. The cutter of Claim 12 wherein said polycry-stalline diamond elements are compactly bundled within said diamond table formed of matrix material so that each polycrystalline diamond element is immediately proximate to an adjacent element.

14. The cutter of Claim 12 wherein said plurality of polycrystalline. diamond elements are disposed within said diamond table in a spaced-apart relationship with said matrix material disposed therebetween.

15. The cutter of Claim 12 wherein said diamond table has an exposed cutting face and said axis of symmetry of said diamond table is generally normal to said cutting face.

16. A diamond cutter for use in a drill bit comprising:
a plurality of leached polycrystalline diamond elements each characterized by a longitudinal axis, said polycrystalline diamond elements arranged and configured in said cutter so that said longitudinal axes are mutually parallel; and diamond bearing matrix material disposed between and about said plurality of polycrystalline diamond elements to form an aggregate diamond table of a predetermined gross shape, whereby an enlarged diamond cutter substantially characterized by the material properties of said plurality of leached polycrystalline diamond elements is provided.

17. The cutter of Claim 16 wherein said diamond table has a cutting face exposed to cutting action and wherein such longitudinal axes of said polycrystalline diamond elements are generally perpendicular to said cutting face.

18. The cutter of Claim 17 wherein said polycrystal-line diamond elements are compactly set within said diamond table so that each polycrystalline diamond element is immediately proximate to at least one adjacent polycrystal-line diamond element.

19. The cutter of Claim 17 wherein said polycrystal-line diamond elements are disposed in said diamond table in a spaced-apart relationship with said diamond bearing matrix material disposed therebetween.

20. The cutter of Claim 16 wherein said diamond bearing matrix material incorporates a uniform distribution of diamond grit.

21. A diamond cutter element for use in a drill bit comprising:
a plurality of thermally stable polycrystalline diamond cutting elements, each characterized by a long-itudinal axis; and a matrix material forming a diamond table, said plurality of polycrystalline diamond elements disposed in said matrix material wherein said longitudinal axes of said elements are generally mutually parallel, said diamond table disposed in said drill bit to present said longitudinal axes of said plurality of polycrystalline diamond cutting elements in a predetermined direction, said diamond table characterized by a cutting direction, said cutting direction defined as the instantaneous direction of displacement of said diamond table as determined by said drill bit when said drill bit is operative.

22. The cutter of Claim 21, wherein said predetermined direction of said longitudinal axes of said plurality of polycrystalline diamond cutting elements is generally parallel to said cutting direction of said diamond table.

23. The cutter of Claim 21, wherein said predeter-mined direction of said longitudinal axes of said poly-crystalline diamond elements is generally perpendicular to said cutting direction of said diamond table.

24. The cutter of Claim 21, wherein said predeter-mined direction of said longitudinal axes of said plurality of polycrystalline diamond cutting elements is inclined with respect to said cutting direction of said diamond table.

25. The cutter of Claim 21, wherein each said poly-crystalline diamond cutting element is characterized by a needle-like shape.

26. The cutter of Claim 21, wherein each said poly-crystalline diamond cutting element is characterized by a needle-like shape.