WO2021069987A1

WO2021069987A1 - Manufacture of polycrystalline superhard cutter utilizing internal wireframe

Info

Publication number: WO2021069987A1
Application number: PCT/IB2020/058561
Authority: WO
Inventors: Federico Bellin; Christopher REYES; Zachary CORDERO
Original assignee: Varel International Ind., L.L.C.; Willaim Marsh Rice University
Priority date: 2019-10-11
Filing date: 2020-09-15
Publication date: 2021-04-15

Abstract

A method for manufacturing a cutter includes: placing a can into a press, the can comprising superhard powder, a plurality of wires embedded in the superhard powder, and catalyst; and operating the press to sinter the superhard powder, thereby forming a polycrystalline superhard cutting head. An outer portion of each wire melts and forms a transition region in the cutting head and an inner portion of each wire remains intact. The method further includes exposing at least a portion of the polycrystalline superhard cutting head to acid for removing at least a portion of the catalyst from the polycrystalline superhard cutting head. The acid tunnels into the polycrystalline superhard cutting head by dissolving at least the inner portion of each wire.

Description

MANUFACTURE OF POLYCRYSTALLINE SUPERHARD CUTTER UTILIZING

INTERNAL WIREFRAME

BACKGROUND OF THE DISCLOSURE Field of the Disclosure

[0001] The present disclosure generally relates to manufacture of a polycrystalline superhard cutter utilizing an internal wireframe.

Description of the Related Art

[0002] US 4,288,248 discloses a compact for tools, such as cutting, drilling and shaping tools, consists essentially of self-bonded abrasive particles. The bonded particles define a substantially continuous interconnected network of pores, dispersed throughout the compact. The method for making such a compact comprises the steps of bonding a mass of abrasive particles, aided by a sintering aid material, under high temperatures and pressures (HP/HT) to form an abrasive body comprised of said particles in a self-bonded form and said material infiltrated throughout the body. The body is then treated to remove substantially all infiltrated material, thereby to produce a compact consisting essentially of the self-bonded abrasive particles. In another embodiment, a composite compact which is made in a similar manner to the first embodiment consists essentially of a layer of self-bonded abrasive particle and a substrate layer (preferably of cemented carbide) bonded to the abrasive particle layer.

[0003] US 7,712,553 discloses coating a polycrystalline diamond compact (PDC) cutter having a body of diamond crystals containing a catalyzing material with a material impervious to a given acid. After the coating has dried, a segment of the coating is removed and acid is supplied to the diamond crystal body through the template in the coating to leach out the catalyzing material contained within the body of diamond crystals.

[0004] US 8,997,897 discloses depositing a layer of matrix powder within a mold opening. A layer of super-abrasive particles is then deposited over the matrix powder layer. The super-abrasive particles have a non-random distribution, such as being positioned at locations set by a regular and repeating distribution pattern. A layer of matrix powder is then deposited over the super-abrasive particles. The particle and matrix powder layer deposition process steps are repeated to produce a cell having alternating layers of matrix powder and non-randomly distributed super-abrasive particles. The cell is then fused, for example using an infiltration, hot isostatic pressing or sintering process, to produce an impregnated structure. A working surface of the impregnated structure that is oriented non-parallel (and, in particular, perpendicular) to the super-abrasive particle layers is used as an abrading surface for a tool.

[0005] US 9,175,521 discloses a cutting table including a cutting surface, an opposing surface, a cutting table outer wall, and one or more slots. The cutting table outer wall extends from the circumference of the opposing surface to the circumference of the cutting surface. The slots extend from a portion of the cutting surface to a portion of the cutting table outer wall. The cutting table is leached to form a thermally stable cutting table. One or more slots are positioned in parallel with at least another slot in some embodiments. In some embodiments, the slots are positioned circumferentially around the cutting surface. In some embodiments, at least one slot is backfilled with a backfilling material to increase heat transfer or impact resistance. In some embodiments, the cutting table is coupled to a substrate to form a cutter. The slots are formed either after or during the formation of the cutting table.

[0006] US 9,302,945 discloses a method including depositing alternating layers of a ceramic powder and a pre-ceramic polymer dissolved in a solvent. Each layer of the pre-ceramic polymer is deposited in a shape corresponding to a cross section of an object. The alternating layers of the ceramic powder and the pre-ceramic polymer are deposited until the layers of the pre-ceramic polymer form the shape of the object. The method includes heating the deposited ceramic powder and pre-ceramic polymer to at least a decomposition temperature of the pre-ceramic polymer. The decomposition temperature of the pre-ceramic polymer is less than a sintering temperature of the ceramic powder. The method further includes removing excess ceramic powder that the pre-ceramic polymer was not deposited onto.

[0007] US 9,393,674 discloses a carbide composite for a downhole tool formed by depositing a first layer on a substrate, and a second layer at least partially adjacent to the first layer. The first and second layers may each include carbides, metal binders, organic binders, or a combination thereof. The first and second carbide layers may have a different particle size, particle shape, carbide concentration, metal binder concentration, or organic binder concentration from one another.

[0008] US 2014/0069726 discloses varying the rate of leaching of a polycrystalline diamond (PCD) cutting layer for cutting elements or other wear parts by introduction into the PCD of an additive prior to leaching. Selective introduction of the additive into one or more regions of a PCD cutting structure allows controlling leaching rates of selective leaching of parts of the PCD structure, which allows for creating of a boundary between the leached and non-leached regions of a PCD structure to be made so that is not parallel to the surface or surfaces exposed to the leaching solution. The additive is comprised of a material that increases the permeability of the PCD or acceptance of the PCD to the leaching solution, such as a hydrophile.

[0009] US 2018/0250647 discloses a lithography based method for the manufacture of diamond composite materials in which green bodies are prepared by a layer-by-layer construction with resulting green bodies de-bound and sintered to achieve a dense high hardness material.

[0010] US 2018/0313163 discloses a cutting table including hard material, and a fluid flow pathway within the hard material. The fluid flow pathway is configured to direct fluid proximate outermost boundaries of the hard material through one or more regions of the hard material inward of the outermost boundary of the hard material. A cutting element and an earth-boring tool are also described.

[0011] US 2020/0130062 discloses a method for manufacturing a cutter including: placing a can into a press, the can comprising superhard powder, a metallic frame embedded in the superhard powder, and catalyst; operating the press to sinter the superhard powder, thereby forming a polycrystalline superhard cutting head; and exposing at least a portion of the polycrystalline superhard cutting head and the frame to acid for removing at least a portion of the catalyst from the polycrystalline superhard cutting head. The leaching frame comprises a plurality of branches. Each branch has an inner end located adjacent to a front face of the cutting head and an outer end located adjacent to a side of the cutting head. The acid tunnels into the polycrystalline superhard cutting head by dissolving the leaching frame.

[0012] WO 2018/050796 discloses a method for manufacturing an impregnated segment includes forming a base tier by depositing one or more layers of molten metallic material. The base tier has a plurality of cavities. The method further includes inserting at least one superhard particle into each cavity and forming an additional tier on top of the base tier by depositing one or more layers of the molten metallic material. The additional tier has a plurality of cavities. The method further includes repeating the insertion of the superhard particles and the formation of additional tiers to form an impregnated cage.

[0013] WO 2018/084839 discloses a sintering assembly and a polycrystalline diamond compact (PDC) including an acid-labile leach-enhancing material, a PDC including cavities formed by removal of an acid-labile leach-enhancing material, and a method of forming a leached PDC using an acid-labile leach-enhancing material. Further disclosed are drill bits using PDCs formed suing an acid-labile leach enhancing material.

[0014] Liu, Chengliang, et al. "Effect of removing internal residual metallic phases on wear resistance of polycrystalline diamond compacts." International Journal of Refractory Metals and Hard Materials 31 (2012): 187-191 discloses effective removal of Internal residual metal phases (mainly cobalt) from polycrystalline diamond compacts (PDCs) by electrolysis to improve their high temperature wear resistance. Through turning granite (dry cutting), the wear resistance of PDCs with different residual metal removal depth (RMRD) was checked. The relationship between the measured wear rate and RMRD was obtained, and the results showed that PDCs treated by electrolysis have a significant improvement in wear resistance. X-ray diffraction (XRD) and scanning electron microscopy (SEM) observation of PDCs' wear surface indicated that diamond-graphite phase transformation occurs for the samples with residual metal phase. The wear mechanism is discussed, and the study suggests that the graphitization is the main wear process of PDCs with internal residual metal phases. [0015] Polushin, N. I., M. S. Ovchinnikova, and M. N. Sorokin. "Reducing the Metal Content in PCD Polycrystalline Diamond Layer by Chemical and Electrochemical Etching." Russian Journal of Non-Ferrous Metals 59.5 (2018): 557- 562 discloses investigating polycrystalline diamond compacts (PDCs), which find broad application in drilling, tool-and-die, and building branches of industry. They are a complex composition of diamond and cermet phases. The diamond phase consists of diamond grains of various granulometric compositions and shapes and forms a strong hard skeleton. A cermet phase serves as a binder. The presence of catalyst metals in a diamond layer of bilayer PDC composite materials lowers their operational properties, because the difference in thermal expansion coefficients between diamond grains and catalyst can lead to material cracking in the cutting process, while a high temperature when fabricating the diamond tool and its operation in the cutting zone can lead to the reverse diamond-graphite phase transition. In order to increase wear-resistance characteristics of diamond PCD composites formed using catalyst metals (cobalt and tungsten), etching of metals from the surface of the tool working zone is performed by two methods, notably, electrochemical and chemical. Electrochemical etching is performed in sulfuric acid with various current modes and concentration, and chemical etching is performed in a mixture of hydrochloric and nitric acids and a mixture of fluoric and nitric acids. The distribution of the chemical composition over the depth of PCD samples after etching is performed using scanning electron microscopy. It is established that electrochemical etching is more active kinetically, while chemical etching is promising for industrial application. Abrasive tests of PCD samples before and after etching show the absence of a noticeable effect of both electrochemical and chemical etching of their abrasive ability.

SUMMARY OF THE DISCLOSURE

[0016] The present disclosure generally relates to manufacture of a polycrystalline superhard cutter utilizing an internal wireframe. In one embodiment, a method for manufacturing a cutter includes: placing a can into a press, the can comprising superhard powder, a plurality of wires embedded in the superhard powder, and catalyst; and operating the press to sinter the superhard powder, thereby forming a polycrystalline superhard cutting head. An outer portion of each wire melts and forms a transition region in the cutting head and an inner portion of each wire remains intact. The method further includes exposing at least a portion of the polycrystalline superhard cutting head to acid for removing at least a portion of the catalyst from the polycrystalline superhard cutting head. The acid tunnels into the polycrystalline superhard cutting head by dissolving at least the inner portion of each wire.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0018] Figure 1A illustrates additive manufacturing of a rough leaching frame, according to one embodiment of the present disclosure. Figures 1 B illustrate the manufactured rough leaching frame.

[0019] Figure 2A illustrates acid finishing of the rough leaching frame. Figure 2B illustrates the manufactured leaching wireframe. Figure 2C illustrates carburizing the leaching wireframe.

[0020] Figure 3A illustrates a wire of the carburized leaching wireframe. Figure 3B illustrates the leaching wireframe loaded into an inner can for a high pressure and high temperature (HPHT) sintering operation. Figure 3C illustrates cutting table powder loaded into the inner can. Figure 3D illustrates a substrate loaded into the inner can and placement of an outer can.

[0021] Figure 4 illustrates the HPHT sintering operation to form a superhard cutter.

[0022] Figure 5A illustrates the effect of carburization of the leaching frame. Figure 5B illustrates an alternative carburization step, according to another embodiment of the present disclosure. [0023] Figure 6A illustrates grinding of the superhard cutter. Figure 6B illustrates leaching of a cutting table of the superhard cutter.

[0024] Figure 7A illustrates the leached cutting table. Figure 7B illustrates brazing of the leached cutter into a blade of a drill bit.

DETAILED DESCRIPTION

[0025] Figure 1A illustrates additive manufacturing of a rough leaching frame 1, according to one embodiment of the present disclosure. The rough leaching frame 1 may be formed using a direct metal deposition (DMD) system 2 to form branches 3 (Figure 1B) on a prefabricated base disk 4. The DMD system 2 may include a robot 5, a deposition head 6, a controller, such as a microcontroller or programmable logic controller (PLC) 7, a material supply system 8, a cooling system 9, an electrical power supply 10, and a pedestal 11.

[0026] The robot 5 may include a base, one or more arms, and an actuator (not shown) for each arm. The base may mount the robot 5 to a floor of a manufacturing facility (not shown). A first arm of the robot 5 may be supported from the base and may be rotated relative to the base by a first actuator. The robot 5 may include one or more additional arms pivotally connected to the first arm and articulated relative thereto by one or more actuators. The deposition head 6 may be fastened to an end of the robot 5 distal from the base.

[0027] The deposition head 6 may include a laser 6z, a nozzle 6n, and a feedback sensor 6s, such as a pyrometer. An upper end of the laser 6z may be fastened to the distal end of the robot 5. An upper end of the nozzle 6n may be fastened to a lower end of the laser 6z. A bracket 6b may be fastened to an outer surface of the laser 6z and the feedback sensor 6s may be fastened to the bracket adjacent to a lower end of the nozzle 6n.

[0028] Alternatively, the deposition head 6 may include an electron beam generator instead of a laser. Alternatively, a welding head may be used instead of the deposition head 6 and a rod feeding system may be used instead of the material supply system 8. [0029] The material supply system 8 may include a compressor 8c, a metering hopper 8h, a delivery flowline 8n, and a transport junction 8j. The metering hopper 8h may be loaded with frame powder 12. The frame powder 12 may be metallic, such as being a metal selected from any of Groups 4, 5, and 7-10 of the Periodic Table, such as cobalt. A discharge of the metering hopper 8h and a discharge of the compressor 8c may each be connected to a respective inlet of the transport junction 8j. A discharge of the transport junction 8j may be connected to the delivery flowline 8n. The delivery flowline 8n may enter the robot 5 at the base and the robot may have one or more fluid swivels to accommodate routing of the flowline therethrough. The delivery flowline 8n may exit the robot 5 at one of the additional arms and lead to a header 6h supported from an outer surface of the laser 6z. A plurality of feed lines may extend from the header 6h to respective ports of the nozzle 6n for delivery of the frame powder 12 toward the focal point of the laser 6z.

[0030] The cooling system 9 may include a reservoir 9r of coolant 9c, such as water, a pump 9p, and a delivery line 9n. An intake of the pump 9p may be connected to the reservoir 9r and the delivery flowline 9n may be connected to a discharge of the pump. The delivery flowline 9n may enter the robot 5 at the base and the fabrication robot may have one or more fluid swivels to accommodate routing of the flowline therethrough. The delivery flowline 9n may exit the robot 5 at the end of at one of the additional arms and lead to the nozzle 6n for application of the coolant thereto.

[0031] The electrical power supply 10 may be in electrical communication with the laser 6z and the arm actuators of the robot 5 via a power cable (only one shown) extending through the respective robot. The feedback sensor 6s and arm actuators may be in electrical communication with the PLC 7 via a respective data cable (only one shown) extending through the robot 5.

[0032] In operation, the rough leaching frame 1 may be designed on a computer aided design (CAD) system to generate a CAD design model. The CAD design model may be converted to a computer aided manufacturing (CAM) format and supplied to the PLC 7. The base disk 4 may be mounted to the pedestal 11. The PLC 7 may then operate the robot 5 to begin deposition of a first slice of the branches 3. Heat generated by the laser 6z may melt the frame powder 12 (or metal portion thereof, if a metal carbide) as the robot 5 moves the deposition head 6 along the pedestal 11, thereby depositing a layer of molten material thereon. The robot 5 may repeat deposition of slices until the rough leaching frame 1 has been formed.

[0033] Alternatively, the rough leaching frame 1 may be formed using a three dimensional printer (not shown). The three dimensional printer may include the controller, a laser, a scanner, a feed piston, a part piston, a housing, a supply of the frame powder 12, and a roller. The scanner may further include a deflector in visual communication with the laser and an actuator for moving the deflector for scanning the laser along a path corresponding to a slice of the rough leaching frame 1. The controller may be in communication with the scanner actuator and an actuator of each piston. The laser may supply a sufficiently intense beam to sinter or melt the frame powder 12. The part piston may be lowered by the controller by an increment corresponding to a thickness of the slice once the slice has been completed by the scanner and laser. The supply piston may be raised to ensure that the roller is supplied with the frame powder 12 and the roller may distribute the frame powder therefrom to the part piston after each slice of the rough leaching frame 1 has been completed.

[0034] Figure 1B illustrates the manufactured rough leaching frame 1. The rough leaching frame 1 may include the base disk 4 and a plurality of the branches 3 extending outward therefrom. The branches 3 may be spaced around the base disk 4 at regular intervals, such as three-hundred sixty degrees divided by the number of branches. The base disk 4 may be circular cross-section and each branch 3 may be cylindrical. Each branch 3 may have a shank 3s and a prong 3p. The shank 3s may have a vertical portion extending from the base disk 4, a slightly curved radial portion, and an elbow connecting the vertical and radial portions. The prong 3p may have a circumferential portion extending from the radial portion of the shank 3s, a radial tip, and an elbow portion connecting circumferential portion and the tip.

[0035] Alterantively, the rough leaching frame 1 may include a base ring instead of the base disk 4.

[0036] Figure 2A illustrates acid finishing of the rough leaching frame 1. Additive manufacturing may only be capable of producing relatively thick branches 3 which are not optimal. To reduce the cross-sectional diameter of the branches 3, the branches may be submerged into a bath of acid 13, such as Aqua regia, a mixture of nitric acid and hydrofluoric acid, nitric acid, sulfuric acid, phosphoric acid, perchloric acid hydrofluoric acid, or any other mixtures thereof, and left therein for a soaking time. The acid 13 may dissolve excess metal from the branches 3, thereby reducing the cross-sectional diameter of the branches to less than one hundred microns, such as ranging between forty and sixty microns. The base disk 4 may be used to suspend the rough leaching frame 1 from a lip of the acid tank 14. An electrode 15e may also be disposed in the acid 13 and a power supply 15p connected thereto via a lead. The power supply 15p may be direct current and have another lead connected to the base disk 4, thereby enhancing the thinning process via electrolysis. Whether the positive lead is connected to the base disk 4 and the negative lead is connected to the electrode 15e or vice versa may depend on the type of acid 13 used.

[0037] Figure 2B illustrates the manufactured leaching wireframe 16. Once the soaking time has elapsed, the leaching wireframe 16 may be removed from the acid bath 13 and rinsed. The dimensions of the thinned wires 17 (each having a prong 17p and shank 17s) may be verified, such as by using a three dimensional scanner.

[0038] Figure 2C illustrates carburizing the leaching wireframe 16. After rinsing, the leaching wireframe 16 may be loaded into a carburization furnace 18. The carburization furnace 18 may include a housing 19, a heating element 20, a controller, such as programmable logic controller (PLC) 21 , a temperature sensor 22, a carbon potential sensor 23, a reactor 24, and a power supply (not shown).

[0039] The reactor 24 may be mounted to a sidewall of the housing 19 and extend through an opening therein. The reactor 24 may include a plurality of concentric tubes, such as a feed tube 24f, a combustion tube 24c, a heater tube 24h, and a generator tube 24g. The reactor 24 may further include a manifold 24m having a first inlet in fluid communication with the feed tube 24f for supplying fuel 25 thereto. The reactor 24 may further include a diffuser 24d connected to a distal end of the feed tube 24f and an igniter (not shown) disposed within the combustion tube 24c adjacent to the diffuser. The manifold 24m may further have a second inlet in fluid communication with the combustion tube 24c for supplying an oxidizer, such as air 26, thereto. The air 26 may flow down an annulus formed between the feed tube 24f and the combustion tube 24c to the diffuser 24d for mixing with the fuel 25. An end of the combustion tube 24c may be closed for diverting exhaust 27 resulting from combustion of the fuel 25 and air 26 up an annulus formed between the combustion tube 24c and the heater tube 24h to an outlet of the manifold 24m. The manifold 24m may also have a baffle isolating the outlet from the second inlet.

[0040] The manifold 24m may further have a third inlet in fluid communication with the generator tube 24g for supplying a mixture 28 of air and enriching gas thereto. The enriching gas may be a hydrocarbon or carbon-oxide. The mixture 28 may flow down an annulus formed between the generator tube 24g and the heater tube 24h for being heated by the counter-flowing exhaust 27 and/or radiation from the combustion. The reactor 24 may further include catalyst 24y packed along a portion of the annulus formed between the generator tube 24g and the heater tube 24h to promote cracking of the mixture 28. The catalyst 24y may be metallic, such as electrolytic nickel. The cracked mixture (not shown) may be discharged from the generator tube 24g into a chamber formed in the housing 19 to establish a carburizing atmosphere therein.

[0041] Before loading of the leaching wireframe 16, the furnace 18 may be preheated to a carburizing temperature and the reactor 24 operated to establish the carburizing atmosphere. The leaching wireframe 16 may be loaded and allowed to sit in the furnace for a predetermined period of time 29 sufficient for carburization thereof.

[0042] Alternatively, the reactor 24 may be omitted and the leaching wireframe 16 may instead be packed with carburizing material. Alternatively, the reactor 24 may be a separate unit from the furnace 18 and the cracked mixture may be piped thereto.

[0043] Figure 3A illustrates a wire 31 of the carburized leaching wireframe 30. Each wire 31 may include an inner non-carburized core 31 e and an outer carburized sleeve 31v. The sleeve 31v may now be an alloy including the metal discussed above, such as cobalt, and carbon. As illustrated by the concentration line 32, an outer surface of the sleeve 31 v may have a eutectic concentration 32e of carbon and the carbon concentration may be decrease as the radial distance therefrom increases toward the core 31 e. The carbon concentration at the interface between the core 31 e and the sleeve 31 v may be zero. Correspondingly, a liquidus line 33 shows that the core 31 e has a melting point 33m of the core metal and then the liquidus temperature of the sleeve 31v decreases from the interface with the core 31e toward the outer surface of the sleeve 31v as the carbon concentration increases to the eutectic temperature 33e.

[0044] Alternatively, the outer surface of the sleeve 31v may have a carbon concentration of at least ninety percent of the eutectic concentration 32e. Alternatively, the core 31 e may have an inconsequential carbon concentration, such as less than ten percent of the eutectic concentration 32e.

[0045] Figure 3B illustrates the carburized leaching frame 30 loaded into an inner can 34n for a high pressure and high temperature (HPHT) sintering operation. Once carburization has concluded, the leaching frame 30 may be removed from the furnace 18 and rinsed. The leaching frame 30 may then be placed into the inner can 12n. The inner can 12n may be made from a refractory metal and may have a cylindrical cavity formed therein for receiving the carburized leaching frame 30. The carburized leaching frame 30 may be loaded into the inner can 12n so that the base disk 4c rests on a bottom thereof.

[0046] Figure 3C illustrates cutting table powder 35 loaded into the inner can 12n. The cutting table powder 35 may be monocrystalline synthetic diamond. A quantity of the cutting table powder 35 may be poured into the inner can 34n. During or after pouring of the cutting table powder 35, the inner can 34n may be vibrated to compact the cutting table powder. The quantity of cutting table powder 35 may be sufficient to form a layer in the inner can 34n having a thickness sufficient to embed the wires 31 of the carburized leaching frame 30 therein.

[0047] Alternatively, the cutting table powder 35 may be another superhard material powder, such as cubic boron nitride powder, instead of the diamond powder.

[0048] Figure 3D illustrates a substrate 36 loaded into the inner can 34n and placement of an outer can 34o. The substrate 36 may be cylindrical and pre fabricated by a sintering operation, such as hot isotactic pressing. The substrate 36 may be fabricated from a hard material, such as a cermet. The cermet may be a cemented carbide, such as a Group 8-10 (of the Periodic Table) metal-tungsten carbide. The Group 8-10 metal may be cobalt. The Group 8-10 metal may become alloyed with carbon during the hot isotactic pressing of the substrate. The substrate 36 may be inserted into the cavity of the inner can 34n and into engagement with the cutting table powder 35 while a back portion of the substrate may protrude from an end of the inner can 34n. The outer can 34o may then placed over the inner can 34n. The outer can 34o may be made from a refractory metal and may have a cylindrical cavity formed therein for receiving the inner can 34n and the back portion of the substrate 36. The loaded cans 34n,o may then be sealed, thereby forming a can assembly 34.

[0049] Figure 4 illustrates the HPHT sintering operation to form a superhard cutter 37 (Figure 6A). A plurality of can assemblies 34 may be assembled with a liner 38, a heating element 39, a pair of plugs 40, and a cylinder 41 to form a cell 42. The cell 42 may then be inserted into a HPHT press, such as a belt press 43, and the belt press operated to perform the HPHT sintering operation, thereby causing the alloy component of the substrate 36 to melt and sweep into the cutting table powder 35. The molten alloy may act as a catalyst for recrystallization of the superhard monocrystalline diamond into polycrystalline diamond (PCD), thereby forming a coherent cutting table 44 (Figure 6B), while bonding the cutting table and substrate 36 together to form the superhard cutter 37. The base disk 4c may have a diameter corresponding to the diameter of the cutting table 44. A pressure of the HPHT sintering operation may be at least five gigaPascals, such as ranging between five and ten gigaPascals. A temperature of the HPHT sintering operation may range between the eutectic temperature 33e and the melting point 33m (both at the sintering pressure), such as the eutectic temperature plus forty to ninety percent of the difference between the two temperatures.

[0050] Alternatively, a cubic press may be used to perform the HPHT sintering operation instead of the belt press 43. Alternatively, the inner can 34n may have a nonplanar bottom for forming a shaped cutting head instead of the planar cutting head, such as the cutting table 44. [0051] Figure 5A illustrates the effect of carburization of the leaching frame 30. For comparison, shown on the left of the Figure is the non-carburized wire 17 after the HPHT sintering operation and shown on the right of the Figure is the carburized wire 31 after the HPHP sintering operation. During the HPHT sintering operation, each carburized sleeve 31v (or at least fifty percent thereof) may melt and mix with the cutting table powder 35, thereby forming an impregnated transition region 45 in the cutting table 44 adjacent to the respective intact cores 31 e. The transition region 45 may include the alloy 45a of the sleeve 31 v and the monocrystalline cutting table powder 35. The transition region 45 may serve to lessen the steep gradient 47s of mechanical properties, such as Young’s modulus E, between the polycrystalline superhard material 46 in the cutting table 44 and the metal of each core 31 e/wire 17. This less steep gradient 47g due to the transition region 45 reduces risk of cracks forming in the cutting table 44 adjacent to the cores 31 e.

[0052] Figure 5B illustrates an alternative carburization step, according to another embodiment of the present disclosure. Instead of carburizing the wireframe 16 using the carburization furnace 18, a carburization step may be added to the HPHT sintering operation. The belt press 43 may be operated to exert the sintering pressure 48 on an alternative cell (including the non-carburized wireframes 16 instead of the carburized wireframes 30) and the heating element 39 may be operated to heat the alternative cell to the carburizing temperature 49c and the temperature may be kept for a carburizing time. During the carburizing time, carbon from the cutting table powder 35 may diffuse into the sleeve 31 v. The carburizing temperature 49c may be less than the eutectic temperature 33e (at the sintering pressure 48). The heating element 39 may then be operated to heat the alternative cell to the sintering temperature 49s (discussed above) and the temperature may be kept for the sintering time.

[0053] Figure 6A illustrates grinding of the superhard cutter 37. The cutter 37 may be removed from the cell 42 and inserted into a cylindrical grinder 50 and/or other finishing machines to remove excess material, polish surfaces thereof, and form a chamfer 44m (Figure 6B) into a periphery of the cutting table 44 at a front face 44f (Figure 6B) thereof distal from the substrate 36 and a chamfer 36m (Figure 6B) into a periphery of the substrate 36 at the back end thereof. During the finishing process, the base disk 4c may be ground off from the cutting table 44.

[0054] Figure 6B illustrates leaching of the cutting table 44. Figure 7 A illustrates the leached cutting table 44c. The cores 31 e may have inner ends at, such as flush with, the front face 44f of the cutting table 44 and may extend backward and outward from the front face such that outer ends thereof are adjacent to, such as flush with, a side 44s of the cutting table and behind the chamfer 44m.

[0055] A portion of the substrate 36 and the side 44s of the cutting table 44 may be masked 51. At least a front portion of the cutting table 44 may then be submerged into a bath of acid 52 and left therein for a soaking time. The acid 52 may be any of those discussed above for the acid 13. The acid 52 may dissolve at least the cores 31 e and may also dissolve the sleeve alloy 45a of the transition regions 45, thereby forming leaching tunnels into the cutting table 44 along the cores. Facilitated by the leaching tunnels, the acid 52 may leach at least a substantial portion of the catalyst from a portion of the cutting table 44 adjacent to the front face 44f and side 44s thereof. Figure 7A specifically illustrates leached regions 53 of the cutting table 44c attributable to the leaching tunnels. For clarity, the leached regions attributable to the acid 52 migrating through the non-wired regions of the cutting table 44 are not shown. The acid 52 will also migrate through interstitial spaces in the cutting table to create additional leached regions which will merge with the leached regions 53 attributable to the leaching tunnels. Merging of the leached regions 53 may create a thermally stable region including the front face 44f, the chamfer 44c, and a portion of the side 44s adjacent to the chamfer.

[0056] Alternatively, a portion of the side 44s of the cutting table 44 including the outer ends of the cores 31 e may also be unmasked during the leaching process.

[0057] Figure 7B illustrates brazing of the leached cutter 37c into a blade 54 of a drill bit 55. The brazing operation may be manual or automated. A plurality of the leached cutters 37c may be mounted into pockets formed in a leading edge of the blade 54. Each leached cutter 37c may be delivered to the pocket by an articulator 56. A brazing material 57 may be applied to an interface formed between the pocket and the leached cutter 37c using an applicator 58. As the brazing material 57 is being applied to the interface, the articulator 56 may rotate the leached cutter 37c relative to the pocket to distribute the brazing material 57 throughout the interface. A heater (not shown) may be operated to melt the brazing material 57. Cooling and solidification of the brazing material 57 may mount the leached cutter 37c to the blade 54. The brazing operation may then be repeated for mounting additional cutters into additional pockets formed along the leading edge of the blade 54. The pocket may be inclined relative to a bottom face of the blade adjacent thereto by a back-rake angle. The back rake angle may range between ten and thirty degrees.

[0058] The drill bit 55 may include a bit body 59, a shank 60, a cutting face, and a gage section 61. A lower portion of the bit body 59 adjacent to the cutting face may be made from a composite material, such as a ceramic and/or cermet body powder infiltrated by a metallic binder and an upper portion of the bit body adjacent to the shank 60 may be made from a softer material than the composite material of the upper portion, such as a metal or alloy shoulder powder infiltrated by the metallic binder. The bit body 59 may be mounted to the shank 60 during molding thereof. The shank 60 may be tubular and made from a metal or alloy, such as steel, and have a coupling, such as a threaded pin, formed at a longitudinal end thereof for connection of the drill bit 55 to a drill collar (not shown). The shank 60 may have a flow bore formed therethrough and the flow bore may extend into the bit body 59 to a plenum thereof. The cutting face may form a lower end of the drill bit 55 and the gage section 61 may form an outer portion thereof.

[0059] Alternatively, the bit body 59 may be metallic, such as being made from steel, and may be hardfaced. The metallic bit body may be connected to a modified shank by threaded couplings and then secured by a weld or the metallic bit body may be monoblock having an integral body and shank.

[0060] The cutting face may include one or more primary blades (not shown), one or more secondary blades 54, fluid courses formed between the blades, and the leached cutters 37c. The cutting face may have one or more sections, such as an inner cone, an outer shoulder, and an intermediate nose between the cone and the shoulder sections. The blades 54 may be disposed around the cutting face and each blade may be formed during molding of the bit body 59 and may protrude from a bottom of the bit body. The primary blades and the secondary blades 54 may be arranged about the cutting face in an alternating fashion. The primary blades may each extend from a center of the cutting face, across (the rest of) the cone and nose sections, along the shoulder section, and to the gage section 61. The secondary blades 54 may each extend from a periphery of the cone section, across the nose section, along the shoulder section, and to the gage section 61. Each blade 54 may extend generally radially across the cone (primary only) and nose sections with a slight spiral curvature and along the shoulder section generally longitudinally with a slight helical curvature. Each blade 54 may be made from the same material as the bit body 59. The leached cutters 37c may be mounted along leading edges of the blades 54.

[0061] One or more ports 62 may be formed in the bit body 59 and each port may extend from the plenum and through the bottom of the bit body to discharge drilling fluid (not shown) along the fluid courses. Once the leached cutters 37c have been mounted to the respective blades 54, a nozzle (not shown) may be inserted into each port 62 and mounted to the bit body 59, such as by screwing the nozzle therein.

[0062] The gage section 61 may define a gage diameter of the drill bit 55. The gage section 61 may include a plurality of gage pads, such as one gage pad for each blade 54 and junk slots formed between the gage pads. The junk slots may be in fluid communication with the fluid courses formed between the blades 54. The gage pads may be disposed around the gage section 61 and each pad may be formed during molding of the bit body 59 and may protrude from the outer portion of the bit body. Each gage pad may be made from the same material as the bit body 59 and each gage pad may be formed integrally with a respective blade 54. Each gage pad may extend upward from a shoulder portion of the respective blade 54 to an exposed outer surface of the shank 60.

[0063] In use (not shown), the drill bit 55 may be assembled with one or more drill collars, such as by threaded couplings, thereby forming a bottomhole assembly (BHA). The BHA may be connected to a bottom of a pipe string, such as drill pipe or coiled tubing, thereby forming a drill string. The BHA may further include a steering tool, such as a bent sub or rotary steering tool, for drilling a deviated portion of the wellbore. The pipe string may be used to deploy the BHA into the wellbore. The drill bit 55 may be rotated, such as by rotation of the drill string from a rig (not shown) and/or by a drilling motor (not shown) of the BHA, while drilling fluid, such as mud, may be pumped down the drill string. A portion of the weight of the drill string may be set on the drill bit 55. The drilling fluid may be discharged by the nozzles and carry cuttings up an annulus formed between the drill string and the wellbore and/or between the drill string and a casing string and/or liner string.

[0064] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope of the invention is determined by the claims that follow.

Claims

Claims:

1. A method for manufacturing a cutter, comprising: placing a can into a press, the can comprising superhard powder, a plurality of wires embedded in the superhard powder, and catalyst; operating the press to sinter the superhard powder, thereby forming a polycrystalline superhard cutting head, wherein an outer portion of each wire melts and forms a transition region in the cutting head and an inner portion of each wire remains intact; and exposing at least a portion of the polycrystalline superhard cutting head to acid for removing at least a portion of the catalyst from the polycrystalline superhard cutting head, wherein the acid tunnels into the polycrystalline superhard cutting head by dissolving at least the inner portion of each wire.

2. The method of claim 1, wherein, before placing the can into the press, the wires extend from a base, thereby forming a wireframe.

3. The method of claim 2, further comprises: loading the wireframe into the can; and loading superhard powder into the can.

4. The method of claim 2, further comprising grinding off the base of the wireframe from the polycrystalline superhard cutting head.

5. The method of claim 2, further comprising, before placing the can into the press: forming a rough frame using an additive manufacturing system; and exposing branches of the rough frame to acid, thereby reducing a cross- sectional diameter thereof and forming the wires.

6. The method of claim 5, further comprising using electrolysis to enhance the reduction of the cross-sectional diameter of the branches.

7. The method of claim 1, further comprising, before sintering, carburizing the wires.

8. The method of claim 7, wherein the wires are carburized using a carburization furnace.

9. The method of claim 7, wherein the wires are carburized using the press.

10. The method of claim 1, wherein the inner portion of each wire has an inner end located adjacent to a front face of the cutting head and an outer end located adjacent to a side of the cutting head.

11. The method of claim 10, further comprising forming a chamfer in a periphery of the cutting head at the front face, wherein the outer end of the inner portion of each wire is behind the chamfer.

12. The method of claim 1, wherein the wires are made from a metal selected from Groups 4, 5, and 7-10 of the Periodic Table.

13. The method of claim 1, wherein a cross-sectional diameter of each wire is less than one hundred microns.

14. The method of claim 1, wherein the cutting head is a cutting table.

15. The method of claim 1, wherein: the can comprises catalyst by loading a substrate into the can, and the substrate is bonded to the polycrystalline superhard cutting table while operating the press.