CA1245624A

CA1245624A - Multi-component cutting element using polycrystalline diamond disks

Info

Publication number: CA1245624A
Application number: CA000477325A
Authority: CA
Inventors: Clifford R. Pay; Alexander K. Meskin
Original assignee: Eastman Christensen Co
Current assignee: Baker Hughes Oilfield Operations LLC
Priority date: 1984-03-26
Filing date: 1985-03-25
Publication date: 1988-11-29
Also published as: EP0157278A2; EP0157278A3; AU3946885A; DE3574043D1; EP0157278B1; JPS60242291A

Abstract

MULTI-COMPONENT CUTTING ELEMENT USING
POLYCRYSTALLINE DIAMOND DISKS

ABSTRACT OF THE DISCLOSURE
A diamond cutting table having the geometric characteristics of larger unleached diamond compact products and yet characterised by the physical properties of smaller leached diamond products is fabricated by forming a diamond cutter incorporating a plurality of polycrystalline diamond (PCD) leached disks. The PCD leached disks are disposed in array in a cutting slug formed of matrix material. The matrix material is disposed between and around the plurality of diamond disks and in one embodiment incorporates a volume distribution of diamond grit. The cutting slug is hot pressed or infiltrated to form an integral mass or table. The diamond table is then bonded to a cutter or directly molded into an integral tooth within a matrix body bit.

Description

¦i 124~62~ CHP-6122 1 MULTI-COMPONENT CUl~TING ELEMENT USING

2 POLYCRYSTALLINE DlAMOND DISKS

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.

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.

27 ¦ Later, the commercial production of synthetically 2~ ~
ll -2-~k ~ i6~

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.

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 ~2~

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.

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.

~ 12~5~;2~

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.

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 28 ~

1~456;~ ~

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.

28~

'LZ~5~24 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.

14 Figure 4 is a perspective view of a second embodiment of the invention showing a triangular ~haped multicomponent cutting 16 element.

18 Figure 5 is a third embodiment of the invention showing 19 a perspective view of a multicomponent rectangular shaped cutting element.

22These and other embodiments can best be understood by 23ewing the above drawings in light of the following deRcription.

I

~ 12~5624 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.

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 I -S-~ i6~

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.
_g_ 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.
2~
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.

1~'~5~;24 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.

~2~

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.

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 ~56~4 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 ~ 562~

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.

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 ~5~

2 he f ol low ing cl a ims .

~28

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An improvement in a cutter for use in a matrix metal drag bit manufactured by metallic infiltration comprising an enlarged diamond table for providing a cutting surface, said diamond table incorporated into said cutter in said drag bit during infiltration of said bit, said enlarged diamond table comprising a metal matrix binder and a plurality of thermally stable polycrystalline diamond disks each having at least one end surface, said one end surface of said plurality of diamond disks fully exposed on a cutting face of said cutter and coplanar therewith, said cutting face predominantly forming an exposed diamond-only surface, said plurality of diamond disks being embedded within said matrix binder, whereby an enlarged diamond cutter is fabricated for use within said drag bit.

2. The cutter of claim 1 wherein said matrix binder incorporates diamond grit in at least that portion of said diamond table where said diamond disks are exposed.

3. The cutter of claim 1 wherein said plurality of polycrystalline diamond disks are each formed of pre-fabricated synthetic polycrystalline diamond formed as right circular disks.

4. The cutter of claim 3 wherein said circular disks are disposed within said diamond table in an array, said array disposed in compact form wherein each of said polycrystalline diamond disks is immediately proximate to at least one polycrystalline diamond disk.

5. The cutter of claim 3 wherein said polycrystalline diamond disks are disposed in an array in said diamond table wherein said polycrystalline diamond disks are formed in a spaced-apart relationship, said matrix binder disposed be-tween each polycrystalline diamond disk and no two poly-crystalline diamond disks being in immediate proximity with any other.

6. The cutter of claim 1 wherein said matrix binder incorporating said diamond incorporates a dispersion of diamond grit uniformly throughout said diamond table.

7. The cutter of claim 1 wherein said diamond table is characterized by a cutting face, said diamond grit disposed in said matrix binder being disposed only in that portion of said diamond table in the proximity of said cutting face.

8. A diamond cutter in a rotating bit comprising:
a plurality of circular leached, prefabricated poly-crystalline diamond synthetic disks each having at least one end surface; and a cutting slug formed of matrix material, said plurality of polycrystalline diamond disks disposed within said cutting slug and said matrix material filling between said plurality of polycrystalline diamond disks, said cutting slug characterized by a cutting face, said one end surface of said polycrystalline disks fully exposed on said cutting face, said matrix material forming said cutting slug further comprising diamond grit incorporated at least in that portion of said cutting slug adjacent to said cutting face, said one end surfaces of said plurality of polycrystalline diamond disks collectively comprising said cutting face of said cutting slug, said cutting face predominantly forming an exposed diamond-only surface whereby an enlarged diamond cutter is provided for mounting in said drag bit, and whereby said diamond cutter simulates an integral diamond table.

9. The cutter of Claim 8 wherein said diamond grit incorporated within said matrix material forming said cutting slug is substantially uniformly disposed throughout said cutting slug.

10. The cutter of claim 9 wherein said cutting slug is characterized by a thickness substantially equal to the thickness of said polycrystalline diamond disks.

11. The cutter of claim 10 wherein said cutting slug is bonded to a stud cutter.

12. The cutter of claim 10 wherein said cutting slug is directly infiltrated into an integral cutting tooth of a matrix body bit.

13. The cutter of claim 10 wherein said poly-crystalline diamond circular disks are disposed within said cutting slug in a compact array wherein each said poly-crystalline diamond disk is immediately proximate to and touching at least one adjacent polycrystalline diamond disk.

14. The cutter of claim 10 wherein said plurality of polycrystalline diamond circular disks are disposed in an array in said cutting slug in a spaced-apart relation-ship, said diamond bearing matrix binder forming said cutting slug disposed between said spaced apart poly-crystalline diamond circular disks, no one polycrystalline diamond circular disk being immediately proximate to an adjacent one.