The present invention relates generally to a cutting element and a method of making a superabrasive cutter; and more particularly, to polycrystalline diamond drill blanks with improved carbide interface geometries.
Polycrystalline cubic boron nitride (PcBN), diamond or diamond composite materials are commonly used to provide a superhard cutting edge for cutting tools such as those used in metal machining or rock drilling.
Various polycrystalline diamond cutters have been proposed in which the diamond/carbide interface contains a number of non-planar features designed to increase the mechanical bond and reduce thermally induced residual stresses. However, high tensile residual stresses and high potential shock waves damages still exist at the diamond surface and near the interface in those designs.
Therefore, it can be seen that there is a need for a superabrasive cutter having a high resistance to shock waves when the superabrasive cutter is used to drill rocks.
In one embodiment, a cutting element may comprise a substrate having an inner face and an annular face, wherein the inner face has a center, the annular face has a periphery; and a superabrasive layer attaching to the substrate along the inner face and the annular face, wherein the inner face slopes outwardly and upwardly from the center at an angle ranging from between about 1° and about 7° degrees from horizontal.
In another embodiment, a cutting element may comprise a substrate having an inner face and an annular face, wherein the inner face has a center, the annular face has a periphery; wherein the inner face and the annular face of the substrate have a plurality of spaced-apart protrusions, wherein the center of the substrate is lower than the periphery of the annular face horizontally.
In yet another embodiment, a method of making a cutting element may comprise steps of providing a substrate having an inner face and an annular face, wherein the inner face has a center, the annular face has a periphery, wherein the inner face and the annular face have uneven geometry which is designed to deflect shock waves during an application; providing a superabrasive layer to the substrate along the inner face and the annular face; and subjecting the substrate and the superabrasive layer to a high pressure high temperature condition.
The foregoing summary, as well as the following detailed description of the embodiments, will be better understood when read in conjunction with the appended drawings. It should be understood that the embodiments depicted are not limited to the precise arrangements and instrumentalities shown.
a is a perspective view of a substrate of the cutting element according to an exemplary embodiment;
b is a cross-sectional view of the substrate according to an exemplary embodiment as shown in
a is a perspective view of a substrate of the cutting element according to another exemplary embodiment;
b is a cross-sectional view of the substrate according to the exemplary embodiment as shown in
a is a perspective view of a substrate of the cutting element according to yet another exemplary embodiment;
b is a cross-sectional view of the substrate according to the exemplary embodiment as shown in
a is a perspective view of a substrate of the cutting element according to still another exemplary embodiment;
b is a cross-sectional view of the substrate according to the exemplary embodiment as shown in
a is a perspective view of a substrate of the cutting element according to further another exemplary embodiment;
b is a cross-sectional view of the substrate according to the exemplary embodiment as shown in
a is a perspective view of a substrate of the cutting element according to further exemplary embodiment;
b is a cross-sectional view of the substrate according to the exemplary embodiment as shown in
a is a perspective view of the substrate of the cutting element according to yet further exemplary embodiment;
b is a cross-sectional view of the substrate according to the exemplary embodiment as shown in
Before the present methods, systems and materials are described, it is to be understood that this disclosure is not limited to the particular methodologies, systems and materials described, as these may vary. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope. For example, as used herein, the singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise. In addition, the word “comprising” as used herein is intended to mean “including but not limited to.” Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.
Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as size, weight, reaction conditions and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
As used herein, the term “about” means plus or minus 10% of the numerical value of the number with which it is being used. Therefore, about 50 means in the range of 45-55.
As used herein, the term “superabrasive particles” may refer to ultra-hard particles having a Knoop hardness of 5000 KHN or greater. The superabrasive particles may include diamond, cubic boron nitride, for example. The term “substrate” as used herein means any substrate over which the superabrasive layer is formed. For example, a “substrate” as used herein may be a transition layer formed over another substrate.
As used herein, the term “fractal”, means an infinite geometric series having the shape of a set arranged similar to the shape of each member of the set and repeating this regularity to develop greater sets. The term “near fractal”, means a near infinite geometric series having the shape of a set arranged similar to the shape of each member of the set and repeating this regularity to develop greater sets.
A cutting element, such as polycrystalline diamond composite (or “PDC”, as used hereafter) may represent a volume of crystalline diamond grains with embedded foreign material filling the inter-grain space. In one particular case, composite comprises crystalline diamond grains, bonded to each other by strong diamond-to-diamond bonds and forming a rigid polycrystalline diamond body, and the inter-grain regions, disposed between the bonded grains and filled with a catalyst material (e.g. cobalt or its alloys), which was used to promote diamond bonding during fabrication. Suitable metal solvent catalysts may include the metals in Group VIII of the Periodic table. PDC cutting element (or “PDC cutter”, as is used thereafter) comprises an above mentioned polycrystalline diamond body attached to a suitable support substrate, e.g. cemented cobalt tungsten carbide (WC—Co), by virtue of the presence of cobalt metal.
In another particular case, polycrystalline diamond composite comprises a plurality of crystalline diamond grains, which are not bonded to each other, but instead are bound together by foreign bonding materials such as borides, nitrides, carbides, e.g. SiC.
Polycrystalline diamond composites and PDC cutters may be fabricated in different ways and the following examples do not limit a variety of different types of diamond composites and PDC cutters which can be coated. In one example, PDC cutters are formed by placing a mixture of diamond polycrystalline powder with a suitable solvent catalyst material (e.g. cobalt) on the top of WC—Co substrate, which assembly is subjected to processing conditions of extremely high pressure and high temperature (HPHT), where the solvent catalyst promotes desired inter-crystalline diamond-to-diamond bonding and, also, provides a bonding between the polycrystalline diamond body and the substrate support.
In another example, PDC cutter is formed by placing diamond powder without a catalyst material on top of the substrate containing a catalyst material (e.g. WC—Co substrate). In this example, necessary cobalt catalyst material is supplied from the substrate and melted cobalt catalyst is swept through the diamond powder during the HPHT process. In still another example, a hard polycrystalline diamond composite is fabricated by forming a mixture of diamond powder with silicon powder and mixture is subjected to HPHT process, thus forming a dense polycrystalline cutter where diamond particles are bonded to newly formed SiC material.
Abrasion resistance of polycrystalline diamond composites and PDC cutters may be determined mainly by the strength of bonding between diamond particles (e.g. when cobalt catalyst is used), or, in the case when diamond-to-diamond bonding is absent, by foreign material working as a binder (e.g. SiC binder), or in still another case, by both diamond-to-diamond bonding and foreign binder.
Exemplary embodiments disclose a polycrystalline diamond cutter with a carbide substrate that forms an interface characterized by contoured geometries which impart higher resistance to both wear and fracture during a drilling application. The geometries favorably distribute residual and applied stress such that fewer diamond chips and fractures occur during rock drilling.
In exemplary embodiments, the contoured geometries may be characterized by a series of radiused protrusions from a plane or from a slope or from a raised land, for example. More specifically, the protrusions may be a series of bumps or of raised arcuate extents which have radii smaller than the radius of the substrate, and displaced in patterns which are favorable to HPHT processing. These patterns also serve to disrupt the residual stress field from HPHT processing as well as to deflect damaging shock waves in the diamond during rock drilling.
As shown in
The cutting element 10 may be fabricated according to processes and materials known to persons having ordinary skill in the art. The cutting element 10 may be referred to as a polycrystalline diamond compact (“PDC”) cutter when polycrystalline diamond is used to form the polycrystalline layer 12. PDC cutters are known for their toughness and durability, which allow them to be an effective cutting insert in demanding applications. Although one type of the cutting element 10 has been described, other types of cutting element may be utilized. For example, in some embodiment, superabrasive cutter 10 may have a chamfer (not shown) around an outer peripheral of the top surface 21. The chamfer may have a vertical height of 0.5 mm and an angle of 45° degrees which may provide a particularly strong and fracture resistant tool component.
In an exemplary embodiment, as shown in
In an exemplary embodiment, the annular face 26 and the inner face 30 may have uneven levels, forming a step 44 (shown in
The uneven geometry may further include that the inner face 30 having a plurality of protrusions 32 which may be spaced-apart and arranged in a row 40. The protrusions 32 may be located radially inside the annular face 26. In one exemplary embodiment, the row 40 may be disposed in a circular path around the geometric center of the inner face 30. However, the exemplary embodiment may not be limited to this circular geometry, for example, the row 40 may be elliptical or a symmetrical.
The uneven geometry may further include that the annular face 26 may have a plurality of protrusions 28 which may be spaced-apart and arranged in a row 42. The protrusions 28 may be located radially outside the inner face 30. In one exemplary embodiment, the row 42 may be disposed in a circular path around the geometric center of the inner face 30. However, the exemplary embodiment may not be limited to this circular geometry, for example, the row 40 may be elliptical or a symmetrical.
An end cross-sectional view of one of the protrusions 28 and 32 taken along a diameter plane is shown in
As shown in
In operation, when the cutting element is used in an application, such as a drilling application, the protrusions 32 and arches 32 may deflect shock waves in the superabrasive layer, such as diamond layer. Further, the uneven geometry may favorably distribute residual and applied stress field from high pressure high temperature manufacturing process.
In another exemplary embodiment, as shown in
In yet another exemplary embodiment, as shown in
As shown in
The protrusions 32 and 28 may take various forms, such as T-bones, chevron, V-shape, inverted V-shape, or ridges as shown in
In another embodiment, the protrusions may be characterized by a near-fractal pattern of linear or curvilinear segments which serve to deflect and dissipate shock waves from multiple directions. A fractal pattern is one which is complex and self-similar across different scales. A near-fractal pattern is less complex and more limited in the scales for which the pattern is self-similar. Such aforementioned segments may be of different heights and thicknesses compared to neighboring segments. As an example, a near-fractal pattern may be based on a linear branching pattern as shown in
As shown in
One or more steps may be inserted in between or substituted for each of the foregoing steps 82-86 without departing from the scope of this disclosure.
Cutters were prepared without a bevel on the diamond edge. They were rigidly held in a clamp fixture by gripping on the outer diameter, leaving a section of the diamond edge exposed. Using an Instron Model instrument, the cutter assembly was raised a designated height above an impact bar. The height and weight of the falling tool assembly, including the cutter, determine the energy of the impact. The impact bar was rectangular with a square cross section. It was made of steel that is through-hardened to a hardness of 60 on the Rockwell C scale.
The cutter was positioned within the fixture assembly so that when it was dropped onto the impact bar, the diamond edge impacts at an angle of 15 degrees relative to the diamond-carbide interface. A cutter that failed under impact displayed cracks and/or chips that are easily visible.
The energy of the drop, and therefore the height of the drop, had been pre-determined to cause some failures in some cutters. As examples, drops of 14 joules, or 20 joules or more, provided a means to distinguish product design behavior by using a scoring metric.
The test method used in the present invention consisted of dropping each cutter up to seven times and then scoring the result. If a cutter survived 1 drop without failure, then failed on the second drop, it got a score of 1 out of 7, or 14%. If a cutter survived all 7 drops without failure, it got a score of 100%. Typically, 10 cutters in each test group were dropped and scored. The comparison scores reflected the relative impact resistance in the drop test mode. A higher score meant a more resistant cutter.
The data in
While reference has been made to specific embodiments, it is apparent that other embodiments and variations can be devised by others skilled in the art without departing from their spirit and scope. The appended claims are intended to be construed to include all such embodiments and equivalent variations.
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