Polycrystalline diamond compact cutter having a stress mitigating hoop at the periphery

Information

  • Patent Grant
  • 6189634
  • Patent Number
    6,189,634
  • Date Filed
    Friday, September 18, 1998
    26 years ago
  • Date Issued
    Tuesday, February 20, 2001
    23 years ago
Abstract
A cutting element, insert or compact, is provided for use with drills used in the drilling and boring of subterranean formations. This new insert, in its preferred embodiment, has a “hoop” region of polycrystalline diamond extending around the periphery of the compact to reduce the residual stresses inherent in thick diamond regions of cutters. This compact has improved wear and durability characteristics because it avoids failures due to stresses, delaminations and fractures caused by the differences in thermal expansion coefficient between the diamond and the substrate during sintering. Moreover, this invention may provide multiple polycrystalline diamond edges as the PDC wears. This exposure of multiple polycrystalline diamond edges slows the rate of wear flat surface development and reduces the weight on the bit required for acceptable drill penetration rates.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates to devices for drilling and boring through subterranean formations. More specifically, this invention relates to polycrystalline diamond compacts (“PDCs”), also known as cutting elements or diamond inserts, which are intended to be installed as the cutting element of a drill bit to be used for boring through rock in any application, such as oil, gas, mining, and/or geothermal exploration, requiring drilling through geological formations.




2. Description of Related Art




Polycrystalline diamond compacts (PDCs) are used with down hole tools, such as drill bits (including percussion bits; rolling cone bits, also referred to as rock bits; and drag bits, also called fixed cutter bits), reamers, stabilizers and tool joints. A number of different configurations, materials and geometries have been previously suggested to enhance the performance and/or working life of the PDC. The current trend in PDC design is toward relatively thick diamond layers. Typically, thick diamond layers bonded to a tungsten carbide substrate suffer from extremely high residual tensile stresses. These stresses arise from the difference in the thermal expansion between the diamond layer and the substrate after sintering at high temperature and high pressure. These stresses tend to increase with increasing diamond layer thickness. This stress contributes to the delamination and fracture of the diamond layer when the compact is used in drilling.




A polycrystalline diamond compact (“PDC”), or cutting element, is typically fabricated by placing a cemented tungsten carbide substrate into a refractory metal container (“can”) with a layer of diamond crystal powder placed into the can adjacent to one face of the substrate. The components are then enclosed by additional cans. A number of such can assemblies are loaded into a high-pressure cell made from a low thermal conductivity, extrudable material such as pyrophyllite or talc. The loaded cell is then placed in a high pressure press. The entire assembly is compressed under high pressure and high temperature conditions. This causes the metal binder from the cemented carbide substrate to “sweep” from the substrate face through the diamond crystals and to act as a reactive phase to promote the sintering of the diamond crystals. The sintering of the diamond grains causes the formation of a polycrystalline diamond structure. As a result, the diamond grains become mutually bonded to form a diamond mass over the substrate face. The metal binder may remain in the diamond layer within the pores of the polycrystalline structure or, alternatively, it may be removed via acid leeching or optionally replaced by another material, forming so-called thermally stable diamond (“TSD”). Variations of this general process exist and are described in the related art. This detail is provided so the reader may become familiar with the concept of sintering a diamond layer onto a substrate to form a PDC insert. For more information concerning this process, the reader is directed to U.S. Pat. No. 3,745,623, issued to Wentorf Jr. et al., on Jul. 7, 1973.




While thicker diamond layers are often desirable to increase the wear life of the PDC, as described above, such increases in diamond layer thickness often induce internal stresses at the interface between the diamond and the tungsten carbide substrate interface. Previous approaches to minimize these internal stresses include modifying the geometry of the interface to change the pattern of residual stress. However, usually the change in residual stress is relatively minor because a non-planar interface has little effect on the residual stress distribution in a thick diamond layer. The non-planar features are generally so small as to be regarded as nearly planar in relation to the diamond table thickness on a thick diamond cutter.




A number of approaches to the manufacturing process and application of PDCs with thick diamond layers are well established in related art. The applicant includes the following references to related art patents for the reader's general familiarization with this technology.




U.S. Pat. No. 4,539,018 describes a method for fabricating cutter elements for a drill bit.




U.S. Pat. No. 4,670,025 describes a thermally stable diamond compact, which has an alloy of liquidus above 700° C. bonded to a surface thereof.




U.S. Pat. No. 4,690,691 describes a cutting tool comprised of a polycrystalline layer of diamond or cubic boron nitride which has a cutting edge and at least one straight edge wherein one face of the polycrystalline layer is adhered to a substrate of cemented carbide and wherein a straight edge is adhered to one side of a wall of cemented carbide which is integral with the substrate, the thickness of the polycrystalline layer and the height of the wall being substantially equivalent.




U.S. Pat. No. 4,767,050 describes a composite compact having an abrasive particle layer bonded to a support and a substrate bonded to the support by a brazing filler metal having a liquidus substantially above 700° C. disposed there between.




U.S. Pat. No. 4,802,895 describes a composite diamond abrasive compact produced from fine diamond particles in the conventional manner except that a thin layer of fine carbide particles is placed between the diamond particles and the cemented carbide support.




U.S. Pat. No. 4,861,350 describes a tool component, which comprises an abrasive compact bonded to a cemented carbide support body. The abrasive compact has two zones which are joined by an interlocking, common boundary.




U.S. Pat. No. 4,941,891 describes a tool component comprising an abrasive compact bonded to a support which itself is bonded through to an elongated cemented carbide pin.




U.S. Pat. No. 4,941,892 describes a tool component, which comprises an abrasive compact bonded to a support which itself is bonded through an alloy to an elongated cemented carbide pin.




U.S. Pat. No. 5,111,895 describes a cutting element for a rotary drill bit comprising a thin superhard table of polycrystalline diamond material defining a front cutting face, bonded to a less hard substrate.




U.S. Pat. No. 5,120,327 describes a composite for cutting in subterranean formations, which comprises a cemented carbide substrate and a diamond layer adhered to a surface of the substrate.




U.S. Pat. No. 5,176,720 describes a method of producing a composite abrasive compact.




U.S. Pat. No. 5,370,717 describes a tool insert, which comprises an abrasive compact layer having a working surface and an opposite surface bonded to a cemented carbide substrate along an interface. At least one cemented carbide projection extends through the compact layer from the compact/substrate interface to the working surface in which it presents a matching surface.




U.S. Pat. No. 5,469,927 describes a preform cutting element, which comprises a thin cutting table of polycrystalline diamond, a substrate of cemented tungsten carbide, and a transition layer between the cutting table and substrate. The interface between the cutting table and the transition layer is configured and non-planar to reduce the risk of spalling and delamination of the cutting table.




U.S. Pat. No. 5,472,376 describes a tool component, which comprises an abrasive compact layer bonded to a cemented carbide substrate along an interface. The abrasive compact layer has a working surface, on a side opposite to the interface, that is flat and presents a cutting edge or point around its periphery. A recess, having a side wall and a base both of which are located entirely within the carbide substrate, extends into the substrate from the interface.




U.S. Pat. No. 5,560,754 describes a method of making polycrystalline diamond and cubic boron nitride composite compacts, having reduced abrasive layer stresses, under high temperature and high pressure processing conditions.




U.S. Pat. No. 5,566,779 describes a drag bit formed of an elongate tooth made of tungsten carbide and having an elongate right cylinder construction. The end face is circular at the end of a conic taper. The tapered surface is truncated with two 180° spaced flat faces at 15° to about 45° with respect to the axis of the body. A PDC layer caps the end.




U.S. Pat. No. 5,590,727 describes a tool component comprising an abrasive compact, having a flat working surface which presents a cutting edge and an opposite surface bonded to a surface of cemented carbide substrate to define an interface having at least two steps.




U.S. Pat. No. 5,590,728 describes a preform cutting element for a drag-type drill bit that includes a facing table of superhard material having a front face, a peripheral surface, and a rear surface bonded to a substrate which is less hard than the superhard material. The rear surface of the facing table is integrally formed with a plurality of ribs which project into the substrate and extend in directions outwardly away from an inner area of the facing table towards the peripheral surface thereof.




U.S. Pat. No. 5,647,449 describes a crowned insert. The end of the insert is crowned with a PDC layer integrally cast and bonded thereto so that the enlargement is fully surrounded by the PDC crown.




U.S. Pat. No. 5,667,028 describes a polycrystalline diamond composite cutter having a single or plurality of secondary PDC cutting surfaces in addition to a primary PDC cutting surface, where at least two of the cutting surfaces are non-abutting , resulting in enhanced cutter efficiency and useful life. The primary PDC cutting surface is a PDC layer on one end face of the cutter. The secondary PDC cutting surfaces are formed by sintering and compacting polycrystalline diamond in grooves formed on the cutter body outer surface. The secondary cutting surfaces can have different shapes such as circles, triangles, rectangles, crosses, finger-like shapes, or rings.




U.S. Pat. No. 5,685,769 describes a tool compact comprising an abrasive compact layer bonded to a cemented carbide substrate along an interface, with a recess provided that extends into the substrate from the interface. The recess has a shape of at least two stripes which intersect.




U.S. Pat. No. 5,706,906 describes a cutting element for use in drilling subterranean formations.




U.S. Pat. No. 5,711,702 describes a cutting compact having a superhard abrasive layer bonded to a substrate layer, where the configuration of the interface between the abrasive and the substrate layers is a non-planar, or three dimensional to increase the surface area between the layers available for bonding.




U.S. Pat. No. 5,743,346 describes an abrasive cutting element comprised of an abrasive cutting layer and a metal substrate wherein the interface there between has a tangential chamfer the plane of which forms an angle of about 5° to about 85° with the plane of the surface of the cylindrical part of the metal substrate.




U.S. Pat. No. 5,766,394 describes a method for forming a polycrystalline layer of ultra hard material where the particles of diamond have become rounded instead of angular in a multiple roller process.




Each of the aforementioned patents and elements of related art is hereby incorporated by reference in its entirety for the material disclosed therein.




SUMMARY OF THE INVENTION




In drill bits, which are used to bore through subterranean geologic formations, it is desirable to manipulate the harmful stresses created at the superabrasive—substrate interface, the superabrasive surface, and/or at the location of cutter contact with the formation. When present such stresses can reduce the working life of the PDC by causing premature failure of the superabrasive layer. It is also desirable to have PDCs with increasingly thick diamond or cBN superabrasive layers. However, such thick diamond or cBN layers exacerbate the problem of residual stresses. In general, the most damaging tensile stress regions are located on the outer diameter of the cutter in the superabrasive diamond layer just above the diamond—carbide interface. High tensile stress regions may also be found on the cutting face. These stresses increase with increasing diamond layer thickness. On standard cutters, the relatively thin diamond table will be in compression near the center of the diamond face. This invention provides a geometry that manipulates the residual stresses and provides the increased strength and working life of thick diamond layers, by, in its preferred embodiment, providing a polycrystalline diamond layer that extends across the top and down the side of the PDC. A “hoop” of diamond is created about the perimeter of the cutter, which serves to significantly reduce the harmful residual stresses while producing a cutter having improved working life and cutting performance. Additionally, this “hoop” has been found to counteract the bending stress at the diamond—carbide interface. Moreover, the “hoop” induces compressive forces on the top surface and inner diameter of the diamond layer. These compressive forces serve as a barrier to crack propagation, thereby providing a considerable improvement in fracture toughness of the PDC. An additional benefit of the present invention is the creation of two cutting edges as the PDC wears. Typically, thick diamond cutters have large wear flats which tend to behave as bearing surfaces, requiring excessive weight on the bit for reasonable penetration rates. This invention addresses this issue because, although it behaves as a typical PDC cutter during initial wear, as the wear increases the wear flat becomes comprised of a carbide center portion surrounded by diamond, thereby creating two cutting edges. The second cutting edge slows the rate of wear flat development and reduces the weight requirement on the bit for acceptable bit penetration rates.




Therefore, it is an object of this invention to provide a PDC with an enhanced residual stress distribution.




It is a further object of this invention to provide a PDC with a “hoop” geometry that favorably manipulates the residual stresses associated with the differences in thermal expansion between the diamond and the substrate.




It is a further object of this invention to provide a PDC that provides the increased strength and working life of thick diamond layers without the associated increase in external diamond surface tensile stresses.




It is a further object of this invention to provide a PDC with a “hoop” region that counteracts the bending stresses at the diamond—carbide interface.




It is a further object of this invention to provide a PDC with a “hoop” region that provides compressive forces, which serve as a barrier to crack propagation, on the top surface and the inner diameter of the diamond layer of the cutter.




It is a further object of this invention to provide a PDC with a “hoop” region that exposes a plurality of cutting edges during normal wear of the cutter.




These and other objectives, features and advantages of this invention, which will be readily apparent to those of ordinary skill in the art upon review of the following drawings, specification, and claims, are achieved by the invention as described in this application.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

depicts a perspective view of the preferred embodiment of this invention.





FIG. 2

depicts a cross-section view of the preferred embodiment of the invention.





FIGS. 3



a


and


3




b


depict representative views of the preferred embodiment of the invention while in use.

FIG. 3



a


shows the preferred PDC of this invention at initial wear conditions.

FIG. 3



b


shows the preferred PDC of this invention at extended wear conditions.





FIGS. 4



a-l


show top and cross section views of a variety of alternative embodiments of the invention.





FIG. 5

shows the perspective view of an additional embodiment of the invention.





FIGS. 6



a-f


show cross-sectional views of a variety of alternative embodiments of the invention presented in FIG.


5


.





FIGS. 7



a-p


show top and cross-sectional views of additional alternative embodiments of the invention.











DETAILED DESCRIPTION OF THE INVENTION




This invention is intended for use in cutting tools, most typically drag bits, roller cone bits and percussion bits used in oil and gas exploration, drilling, mining, excavating and the like. Typically the bit has a plurality of PDCs mounted on the bit's cutting surface. When the drill bit is rotated, the leading edge of one or more PDCs comes into contact with the rock surface. During the drilling operation, the stresses and pressures imposed on each PDC require that the PDC be capable of sustaining high internal stresses and that the diamond layer of the PDC be strong. The present invention is, in its preferred embodiment, a polycrystalline diamond compact (PDC) cutter with a polycrystalline diamond layer that extends fully across the top and around a portion of the sides of the PDC. The portion of the polycrystalline diamond layer that extends around some or all of the side of the PDC is referred to as a “hoop” region. The preferred thickness of the diamond layer down the side may or may not be the same as the thickness of the top surface of the diamond layer. The thickness selection is made based on the desired stress characteristics. For the purposes of this disclosure, thickness of the top surface of the polycrystalline diamond layer is defined as the distance from the top surface to the nearest carbide region. The thickness of the “hoop” portion of the polycrystalline diamond layer is defined as the distance from the outer edge of the side of the polycrystalline diamond layer to the nearest carbide region. The stress mitigation is controlled mainly by the hoop width


208


and the top layer thickness


207


. The diamond height on the outer diameter


210


is unimportant as long as the width


208


and the thickness


207


are appropriate.





FIG. 1

shows the perspective view of the preferred embodiment of this invention. This view depicts the exterior of the preferred PDC


100


. The polycrystalline diamond region


101


is shown fixed to a carbide substrate region


102


. The preferred bond


103


between the diamond region


101


and the carbide region


102


is accomplished using a sintering process although alternatively a brazing or chemical vapor phase deposition of the polycrystalline diamond can be used. The polycrystalline diamond region


101


is formed of diamond crystals bound together by a high pressure/high temperature process that forms the diamond crystals together into a solid diamond mass. Alternatively, a cubic boron nitride (cBN) or other superabrasive material layer can be substituted for the polycrystalline diamond layer


101


. The preferred substrate region


102


is composed of tungsten carbide, although alternative materials, including titanium carbide, tantalum carbide, vanadium carbide, niobium carbide, hafnium carbide, zirconium carbide, or alloys thereof, can be used for the substrate


102


material. Such superabrasive materials and substrate materials suitable for use in PDC are well known in the art.





FIG. 2

shows the cross-section view of the preferred embodiment of the invention. This view shows the “hoop”


201


region of the polycrystalline diamond layer


101


being bounded by a substrate


102


shelf


204


and a substrate


102


center region


203


side wall


206


. In this depiction of the preferred embodiment of the invention


100


, the top surface


202


and the sidewall


206


of the center region


203


are shown as being generally flat. Alternatively, irregularities, including but not limited to indentations, protrusions, grooves, channels, posts and the like may be imposed on the surface of the top surface


202


and/or the side wall


206


. Similarly, the shelf


204


is shown to be generally flat, although alternatively irregularities including but not limited to indentations, protrusions, grooves, channels, posts and the like may be imposed on the surface of the shelf


204


. Such alternative imposed surface features when used along with the “hoop”


201


of this invention should be considered within the scope of the invention. The thickness dimension


208


of the “hoop”


201


region may be either greater than, less than or equal to the thickness


207


of the top surface of the polycrystalline diamond layer


101


.





FIGS. 3



a


and


3




b


show representative views of the preferred embodiment of the invention under use.

FIG. 3



a


shows the preferred PDC of this invention at initial wear conditions. This view provides a simplified diagram of the preferred PDC of this invention


100


being used to cut a surface


301


. A contact point


302


is shown in contact with the surface


301


. This view shows very little wear on the PDC


100


. An expanded view of the contact point, or wear flat


302


is shown


307


. This expanded view


307


shows the wear point


302


as exposing only polycrystalline diamond


308


of the polycrystalline diamond layer


101


. This is the typical wear flat


302


during the initial wear stage.

FIG. 3



b


shows the preferred PDC of this invention at extended wear conditions. This view also provides a simplified diagram of the preferred PDC of this invention


100


being used to cut a surface


301


. A contact point


303


is shown in contact with the surface


301


. This view shows a significant amount of wear on the PDC


100


. An expanded view of the contact point, or wear flat


303


is shown


308


. This expanded view


308


shows the wear point


303


as exposing both the substrate


306


, material of the substrate


102


, and one or more polycrystalline cutting surfaces


304


,


305


of the polycrystalline diamond layer


101


. This is the typical wear flat


303


during the extended wear stage of the preferred PDC


100


.





FIGS. 4



a-l


show top and cross section views of a variety of alternative embodiments of the invention. Referring to

FIGS. 4



a


and


4




b


, which are the top view and cross section view of an alternative embodiment


400


of the invention.

FIG. 4



a


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


408


center region


432


bounded by a “hoop”


439


region of polycrystalline diamond


414


, as shown in a perspective drawing in

FIG. 1. A

shelf


426


is provided on which the “hoop”


439


region is attached to the substrate


408


. The intersection of the substrate


408


shelf


426


and substrate


408


center region


432


side wall


420


is rounded in this embodiment


400


. Similarly, the intersection of the top surface


445


and the side wall


420


of the center region


432


are rounded. This embodiment


400


of the invention also provides a polycrystalline diamond layer


414


, which covers the entire top surface


445


of the substrate


408


.




Referring to

FIGS. 4



c


and


4




d


, which are the top view and cross section view of a second alternative embodiment


401


of the invention.

FIG. 4



c


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


409


center region


433


bounded by a “hoop”


440


region of polycrystalline diamond


415


, as shown in a perspective drawing in

FIG. 1. A

shelf


427


is provided on which the “hoop”


440


region is attached to the substrate


409


. The intersection of the substrate


409


shelf


427


and substrate


409


center region


433


side wall


421


is extremely rounded in this embodiment


401


. Similarly, the intersection of the top surface


446


and the side wall


421


of the center region


433


are extremely rounded. This embodiment


401


of the invention also provides a polycrystalline diamond layer


415


, which covers the entire top surface


446


of the substrate


409


.




Referring to

FIGS. 4



e


and


4




f


, which are the top view and cross section view of a third alternative embodiment


402


of the invention.

FIG. 4



e


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


410


center region


434


bounded by a “hoop”


441


region of polycrystalline diamond


416


, as shown in a perspective drawing in

FIG. 1. A

shelf


428


is provided on which the “hoop”


441


region is attached to the substrate


410


. The intersection of the substrate


410


shelf


428


and substrate


410


center region


434


side wall


422


slopes upward and toward the center region


434


in this embodiment


402


. The intersection of the top surface


447


and the side wall


422


of the center region


434


forms an obtuse angle. This embodiment


402


of the invention also provides a polycrystalline diamond layer


416


, which covers the entire top surface


447


of the substrate


410


.




Referring to

FIGS. 4



g


and


4




h


, which are the top view and cross section view of a fourth alternative embodiment


403


of the invention.

FIG. 4



g


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


411


center region


435


bounded by a “hoop”


442


region of polycrystalline diamond


417


, as shown in a perspective drawing in

FIG. 1. A

shelf


429


is provided on which the “hoop”


442


region is attached to the substrate


411


. The intersection of the substrate


411


shelf


429


and substrate


411


center region


435


side wall


423


slopes upward and away from the center region


435


in this embodiment


403


. The intersection of the top surface


448


and the side wall


423


of the center region


435


forms an acute angle. This embodiment


403


of the invention also provides a polycrystalline diamond layer


417


, which covers the entire top surface


448


of the substrate


411


.




Referring to

FIGS. 4



i


and


4




j


, which are the top view and cross section view of a fifth alternative embodiment


404


of the invention.

FIG. 4



i


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


412


center region


436


bounded by a “hoop”


443


region of polycrystalline diamond


418


, as shown in a perspective drawing in

FIG. 1. A

shelf


430


is provided on which the “hoop”


443


region is attached to the substrate


412


. The intersection of the substrate


412


shelf


430


and substrate


412


center region


436


side wall


424


slopes upward and away from the center region


436


in this embodiment


404


. The intersection of the top surface


449


, which in this embodiment


404


is the apex of a near parabolic substrate


412


surface, and the side wall


424


of the center region


436


is continuously curved. This embodiment


404


of the invention also provides a polycrystalline diamond layer


418


, which covers the entire top surface


449


of the substrate


412


.




Referring to

FIGS. 4



k


and


4




l


, which are the top view and cross section view of a sixth alternative embodiment


405


of the invention.

FIG. 4



k


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


413


center region


438


bounded by a “hoop”


444


region of polycrystalline diamond


419


, as shown in a perspective drawing in

FIG. 1. A

shelf


431


is provided on which the “hoop”


444


region is attached to the substrate


413


. The intersection of the substrate


413


shelf


431


and substrate


413


center region


438


side wall


425


slopes upward and away from the center region


438


in this embodiment


405


. The intersection of the top surface


450


and the side wall


425


of the center region


438


is curved. This embodiment


405


of the invention also provides a polycrystalline diamond layer


419


, which covers the entire top surface


450


of the substrate


413


.





FIG. 5

shows the perspective view of an additional embodiment of this invention. This view depicts the exterior of the alternative PDC


500


. The polycrystalline diamond region


502


is shown fixed to a carbide substrate region


501


. The preferred bond


504


between the diamond region


502


and the carbide region


501


is accomplished using a sintering process, although alternatively a brazing or chemical vapor phase deposition of the polycrystalline diamond can be used. The polycrystalline diamond region


502


is formed of diamond crystals bound together by a high pressure/high temperature process that forms the diamond crystals together into a solid diamond mass. Alternatively, a cubic boron nitride (cBN) or other superabrasive material layer can be substituted for the polycrystalline diamond layer


502


. The preferred substrate region


501


is composed of tungsten carbide, although alternative materials, including titanium carbide, tantalum carbide, vanadium carbide, niobium carbide, hafnium carbide, zirconium carbide, or alloys thereof, can be used for the substrate


501


material. Such superabrasive materials and substrate materials suitable for use in PDC are well known in the art. This alternative embodiment


500


also provides for an exposed center


503


carbide region. In sum, this embodiment


500


and the embodiments shows in

FIGS. 6



a-f


provide a polycrystalline diamond “hoop” region


502


without a top polycrystalline diamond layer covering the entire substrate surface.




Referring to

FIG. 6



a


, which is the cross section view of a first alternative embodiment


600


of the invention having only a polycrystalline diamond “hoop” region


612


. Residual stress mitigation is provided by the substrate


606


center region


624


bounded by a “hoop”


612


region of polycrystalline diamond, as shown in the perspective drawing of

FIG. 5. A

shelf


630


is provided on which the “hoop”


612


region is attached to the substrate


606


. The intersection of the substrate


606


shelf


630


and substrate


606


center region


624


side wall


636


meets at an approximate right angle


618


in this embodiment


600


.




Referring to

FIG. 6



b


, which is the cross section view of a second alternative embodiment


601


of the invention having only a polycrystalline diamond “hoop” region


613


. Residual stress mitigation is provided by the substrate


607


center region


625


bounded by a “hoop”


613


region of polycrystalline diamond, as shown in the perspective drawing of

FIG. 5. A

shelf


631


is provided on which the “hoop”


613


region is attached to the substrate


607


. The intersection of the substrate


607


shelf


631


and substrate


607


center region


625


side wall


637


meets at an obtuse angle


619


in this embodiment


601


.




Referring to

FIG. 6



c


, which is the cross section view of a third alternative embodiment


602


of the invention having only a polycrystalline diamond “hoop” region


614


. Residual stress mitigation is provided by the substrate


608


center region


626


bounded by a “hoop”


614


region of polycrystalline diamond, as shown in the perspective drawing of

FIG. 5. A

shelf


632


is provided on which the “hoop”


614


region is attached to the substrate


608


. The intersection of the substrate


608


shelf


632


and substrate


608


center region


626


side wall


638


meets at an acute angle


620


in this embodiment


602


.




Referring to

FIG. 6



d


, which is the cross section view of a fourth alternative embodiment


603


of the invention having only a polycrystalline diamond “hoop” region


615


. Residual stress mitigation is provided by the substrate


609


center region


627


bounded by a “hoop”


615


region of polycrystalline diamond, as shown in the perspective drawing of

FIG. 5. A

shelf


633


is provided on which the “hoop”


615


region is attached to the substrate


609


. The intersection of the substrate


609


shelf


633


and substrate


609


center region


627


side wall


639


meets at a curved corner


621


with the side wall


639


generally parallel to the side


642


of this embodiment


603


of the PDC. Although being generally parallel to the side


642


the side wall


639


may include a typical manufacturing draft angle.




Referring to

FIG. 6



e


, which is the cross section view of a fifth alternative embodiment


604


of the invention having only a polycrystalline diamond “hoop” region


616


. Residual stress mitigation is provided by the substrate


610


center region


628


bounded by a “hoop”


616


region of polycrystalline diamond, as shown in the perspective drawing of

FIG. 5. A

shelf


634


is provided on which the “hoop”


616


region is attached to the substrate


610


. The intersection of the substrate


610


shelf


634


and substrate


610


center region


628


side wall


640


meets at a curved corner


622


with the side wall


640


sloping generally upwards and towards the center region


628


of this embodiment


604


of the PDC.




Referring to

FIG. 6



f


, which is the cross section view of a sixth alternative embodiment


605


of the invention having only a polycrystalline diamond “hoop” region


617


. Residual stress mitigation is provided by the substrate


611


center region


629


bounded by a “hoop”


617


region of polycrystalline diamond, as shown in the perspective drawing of

FIG. 5. A

shelf


635


is provided on which the “hoop”


617


region is attached to the substrate


611


. The intersection of the substrate


611


shelf


635


and substrate


611


center region


629


side wall


641


meets at a curved corner


623


with the side wall


641


sloping generally upwards and away from the center region


629


of this embodiment


605


of the PDC.





FIGS. 7



a-p


show top and cross section views of a variety of alternative embodiments of the invention which employ different substrate to polycrystalline diamond interface geometries for the purposes of enhancing the strength and/or the manufacturability of the PDC. Each of these embodiments also incorporates a polycrystalline diamond “hoop” fixed to a substrate shelf. Specific detail concerning these embodiments is provided as follows. Referring to

FIGS. 7



a


and


7




b


, which are the top view and cross section view of an alternative embodiment


700


of the invention.

FIG. 7



a


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


708


center ring


724


bounded by a “hoop”


740


region of polycrystalline diamond


716


, as shown in a perspective drawing in

FIG. 1. A

shelf


732


is provided on which the “hoop”


740


region is attached to the substrate


708


. The intersection of the substrate


708


shelf


732


and substrate


708


center ring


724


side wall


748


is formed in an angle of approximately 90 degrees (although a draft angle may be included for manufacturability), in this embodiment


700


. Similarly, the intersection of the top surface


756


and the side wall


748


of the center ring


724


is formed in an approximately 90 degrees. This embodiment


700


of the invention also provides a polycrystalline diamond layer


716


, which covers the entire top surface


756


of the substrate


708


.




Referring to

FIGS. 7



c


and


7




d


, which are the top view and cross section view of an alternative embodiment


701


of the invention.

FIG. 7



c


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


709


center region


725


bounded by a “hoop”


741


region of polycrystalline diamond


717


, as shown in a perspective drawing in

FIG. 1. A

shelf


733


is provided on which the “hoop”


741


region is attached to the substrate


709


. The intersection of the substrate


709


shelf


733


and substrate


709


center region


725


side wall


749


is formed in an angle of approximately 90 degrees, in this embodiment


701


. Similarly, the intersection of the top surface


757


and the side wall


749


of the center region


725


is formed in an approximately 90 degrees. This embodiment


701


of the invention also provides a polycrystalline diamond layer


717


, which covers the entire top surface


757


of the substrate


709


.




Referring to

FIGS. 7



e


and


7




f


, which are the top view and cross section view of an alternative embodiment


702


of the invention.

FIG. 7



e


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


710


center ring


726


bounded by a “hoop”


742


region of polycrystalline diamond


718


, as shown in a perspective drawing in

FIG. 1. A

shelf


734


is provided on which the “hoop”


742


region is attached to the substrate


710


. The intersection of the substrate


710


shelf


734


and substrate


710


center ring


726


side wall


750


curves upwardly and toward the center


764


of the PDC, in this embodiment


702


. The geometry of the substrate


710


to polycrystalline diamond region


718


, of this embodiment


702


is provided with a substrate


710


concavity


766


positioned approximately at the center


764


of the PDC. This embodiment


702


of the invention also provides a polycrystalline diamond layer


718


, which covers the entire top surface


758


and


734


of the substrate


710


.




Referring to

FIGS. 7



g


and


7




h


, which are the top view and cross section view of an alternative embodiment


703


of the invention.

FIG. 7



g


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


711


center ring


727


bounded by a “hoop”


743


region of polycrystalline diamond


719


, as shown in a perspective drawing in

FIG. 1. A

shelf


735


is provided on which the “hoop”


743


region is attached to the substrate


711


. The intersection of the substrate


711


shelf


735


and substrate


711


center ring


727


side wall


751


curves upwardly and toward the center


765


of the PDC, in this embodiment


703


. The geometry of the substrate


711


to polycrystalline diamond region


719


, of this embodiment


703


is provided with a substrate


711


protrusion


767


extending from the substrate


711


into the polycrystalline diamond region


719


and positioned approximately at the center


765


of the PDC. This embodiment


703


of the invention also provides a polycrystalline diamond layer


719


, which covers the entire top surface


759


and


735


of the substrate


711


.




Referring to

FIGS. 7



i


and


7




j


, which are the top view and cross section view of an alternative embodiment


704


of the invention.

FIG. 7



i


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


712


center region


728


bounded by a “hoop”


744


region of polycrystalline diamond


720


, as shown in a perspective drawing in

FIG. 1. A

shelf


736


is provided on which the “hoop”


744


region is attached to the substrate


712


. The intersection of the substrate


712


shelf


736


and substrate


712


center region


728


side wall


752


is formed in an angle of approximately 90 degrees, in this embodiment


704


. Similarly, the intersection of the top surface


760


and the side wall


752


of the center region


728


is formed in an approximately 90 degrees. This embodiment


701


of the invention also provides a polycrystalline diamond layer


720


, which covers the entire top surface


760


of the substrate


712


.




Referring to

FIGS. 7



k


and


7




l


, which are the top view and cross section view of an alternative embodiment


705


of the invention.

FIG. 7



k


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


713


center region


768


bounded by a “hoop”


745


region of polycrystalline diamond


721


, as shown in a perspective drawing in FIG.


1


. A shelf


737


is provided on which the “hoop”


745


region is attached to the substrate


713


. Protruding from the substrate


713


are a plurality of generally cylindrical knobs or protrusions


729


. The intersection of the substrate


713


shelf


737


and substrate


713


protrusions


729


side walls


753


are formed in an angle of approximately 90 degrees (although a draft angle may be included for manufacturability), in this embodiment


705


. Similarly, the intersection of the top surface


761


of the protrusions


729


and the side wall


753


of the protrusions


729


are formed in an angle of approximately 90 degrees. This embodiment


705


of the invention also provides a polycrystalline diamond layer


721


, which covers the entire top surface


737


and


761


of the substrate


713


.




Referring to

FIGS. 7



m


and


7




n


, which are the top view and cross section view of an alternative embodiment


706


of the invention.

FIG. 7



m


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


714


center region


730


bounded by a “hoop”


746


region of polycrystalline diamond


722


, as shown in a perspective drawing in

FIG. 1. A

shelf


738


is provided on which the “hoop”


746


region is attached to the substrate


714


. The intersection of the substrate


714


shelf


738


and substrate


714


center region


730


side wall


754


is formed in an angle of approximately 90 degrees, in this embodiment


706


. Similarly, the intersection of the top surface


762


and the side wall


754


of the center region


730


is formed in an approximately 90 degrees. This embodiment


706


of the invention also provides a polycrystalline diamond layer


722


, which covers the entire top surface


762


of the substrate


714


.




Referring to

FIGS. 7



o


and


7




p


, which are the top view and cross section view of an alternative embodiment


707


of the invention.

FIG. 7



o


shows the top of the substrate without the polycrystalline diamond region to better show the surface topography of the substrate. Residual stress mitigation is provided by the substrate


715


center region


769


bounded by a “hoop”


747


region of polycrystalline diamond


723


, as shown in a perspective drawing in

FIG. 1. A

shelf


739


is provided on which the “hoop”


747


region is attached to the substrate


715


. Protruding from the substrate


715


are a plurality of generally cylindrical knobs or protrusions


731


. In this embodiment


707


of the invention the knobs


731


generally form a circle within the periphery of the top surface of the substrate


715


. The intersection of the substrate


715


shelf


739


and substrate


715


protrusions


731


side walls


755


are formed in an angle of approximately 90 degrees, in this embodiment


707


. Similarly, the intersection of the top surface


763


of the protrusions


731


and the side wall


755


of the protrusions


731


are formed in an angle of approximately 90 degrees. This embodiment


707


of the invention also provides a polycrystalline diamond layer


723


, which covers the entire top surface


739


and


763


of the substrate


715


.




The described embodiments are to be considered in all respects only as illustrative of the current best mode of the invention known to the inventor at the time of filing the patent application, and not as restrictive. Although a number of alternative embodiments of the invention are provided above, these embodiments are provided only as illustrative and not as exhaustive of potential alternative embodiments of the invention. The scope of this invention is, therefore, indicated by the appended claims rather than by the foregoing description. All devices that come within the meaning and range of equivalency of the claims are to be embraced as within the scope of this patent.



Claims
  • 1. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, comprising:(A) a substrate having a bottom surface, a top surface and having a peripheral edge on said top surface, wherein said top surface of said substrate provides a shelf generally parallel to said top surface; and (B) a layer of superabrasive material, having an interface region where said superabrasive layer is bonded to said top surface of said substrate and wherein said layer of superabrasive material further comprises a hoop extending onto said shelf of said top surface of said substrate, and wherein said layer of superabrasive material is of uniform composition throughout.
  • 2. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 1, wherein said shelf extends completely around said periphery of said top surface of said substrate.
  • 3. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 1, wherein said superabrasive layer completely covers said top surface of said substrate.
  • 4. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 1, wherein said superabrasive layer covers only part of said top surface of said substrate.
  • 5. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 1, wherein said substrate is composed of a material selected from the group consisting of tungsten carbide, titanium carbide, tantalum carbide, vandium carbide, niobium carbide, hafnium carbide, zirconium carbide.
  • 6. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 1, wherein said substrate is composed of at least one carbide alloy.
  • 7. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 1, wherein said superabrasive layer is composed of polycrystalline diamond.
  • 8. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 1, wherein upon extensive contact with a surface to be drilled, becomes extensively worn, and when said compact becomes extensively worn reveals a plurality of polycrystalline diamond surfaces for cutting said surface to be drilled.
  • 9. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 1, wherein said interface region between said layer of superabrasive material and said substrate, further comprises irregularities selected from the group comprising protrusions, grooves, channels, depressions, ribs and posts.
  • 10. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, comprising:(A) a substrate having a bottom surface, a generally non-planar top surface, a side wall surface generally perpendicular to said bottom surface, a shelf generally perpendicular and having a peripheral edge on said top surface, wherein said generally non-planar top surface further comprises a surface irregularity; and (B) a layer of superabrasive material, having an interface region where said superabrasive layer is bonded to said top surface of said substrate and wherein said layer of superabrasive material further comprises a hoop extending onto said shelf of said top surface of said substrate, and wherein said layer of superabrasive material is of uniform composition throughout.
  • 11. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein said surface irregularity is selected from the group consisting of ribs, grooves, depressions, ribs, channels and protrusions.
  • 12. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein said shelf extends completely around said periphery of said top surface of said substrate.
  • 13. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein said superabrasive layer completely covers said top surface of said substrate.
  • 14. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein said superabrasive layer covers only part of said top surface of said substrate.
  • 15. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein said substrate is composed of a material selected from the group consisting of tungsten carbide, titanium carbide, tantalum carbide, vandium carbide, niobium carbide, hafnium carbide, zirconium carbide.
  • 16. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein said substrate is composed of at least one carbide alloy.
  • 17. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein said superabrasive layer is composed of polycrystalline diamond.
  • 18. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein upon extensive contact with a surface to be drilled, becomes extensively worn, and when said compact becomes extensively worn reveals a plurality of polycrystalline diamond surfaces for cutting said surface to be drilled.
  • 19. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 10, wherein said interface region between said layer of superabrasive material and said substrate, further comprises irregularities selected from the group comprising protrusions, grooves, channels, depressions, ribs and posts.
  • 20. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, comprising:(A) a substrate having a bottom surface, a generally planar top surface, a side wall surface generally perpendicular to said bottom surface, a shelf generally perpendicular and having a peripheral edge on said top surface, wherein said top surface of said substrate provides a shelf generally parallel to said planar top surface; and (B) a layer of superabrasive material, having an interface region where said superabrasive layer is bonded to said top surface of said substrate and wherein said layer of superabrasive material further comprises a hoop extending onto said shelf of said top surface of said substrate, and wherein said layer of superabrasive material is of uniform composition throughout.
  • 21. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 20, wherein said shelf extends completely around said periphery of said top surface of said substrate.
  • 22. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 20, wherein said superabrasive layer completely covers said top surface of said substrate.
  • 23. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 20, wherein said superabrasive layer covers only part of said top surface of said substrate.
  • 24. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 20, wherein said substrate is composed of a material selected from the group consisting of tungsten carbide, titanium carbide, tantalum carbide, vandium carbide, niobium carbide, hafnium carbide, zirconium carbide.
  • 25. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 20, wherein said substrate is composed of at least one carbide alloy.
  • 26. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 20, wherein said superabrasive layer is composed of polycrystalline diamond materials.
  • 27. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 20, wherein upon extensive contact with a surface to be drilled, becomes extensively worn, and when said compact becomes extensively worn reveals a plurality of polycrystalline diamond surfaces for impacting said surface to be drilled.
  • 28. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, as recited in claim 20, wherein said interface region between said layer of superabrasive material and said substrate, further comprises irregularities selected from the group comprising protrusions, grooves, channels, depressions, ribs and posts.
  • 29. A polycrystalline diamond compact for use on a bit for drilling subterranean formations, comprising:(A) a substrate having a bottom surface, a top surface, a side wall surface generally perpendicular to said bottom surface, a shelf generally perpendicular and having a peripheral edge on said top surface, wherein said top surface of said substrate provides a shelf generally parallel to said bottom surface extending on said peripheral edge; and (B) a layer of superabrasive material, having an interface region where said superabrasive layer is bonded to said top surface of said substrate and wherein said layer of superabrasive material further comprises a hoop, having a width and a depth, extending onto said shelf of said top surface of said substrate, and wherein depth of said hoop is greater in dimension that said width of said hoop.
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