Method for manufacturing a drill bit

In one aspect of the present invention, a drill bit has a body intermediate a shank and a working face, the working face comprising a plurality of blades formed on the working face and extending outwardly from the bit body. Each blade comprises at least one cutting element. The drill bit also has a jack element coaxial with an axis of rotation and extending out of an opening formed in the working face. A portion of the jack element is coated with a stop-off.

BACKGROUND OF THE INVENTION

The present invention relates to the manufacturing of drill bit assemblies for use in oil, gas and geothermal drilling. Drill bit assemblies typically have a number of cutting elements brazed onto a drill bit body. Such cutting elements generally include a diamond surface bonded to a carbide substrate and the carbide substrate is generally brazed into a pocket formed in the drill bit body.

U.S. Pat. No. 4,711,144 to Barr et al., which is herein incorporated by reference for all that it contains, discloses a method of mounting a cutter, having a stud portion defining one end thereof and a cutting formation generally adjacent the other end, in a pocket in a drill bit body member. The method includes the steps of forming a channel extending into the pocket, inserting brazing material into the channel, inserting the stud portion of the cutter assembly into the pocket, then heating the bit body member to cause the brazing material to flow through the channel into the pocket, and finally re-cooling the bit body member. During the assembly of the various pieces required in the steps mentioned immediately above, a spring is used, cooperative between the cutter and the bit body member, to retain the stud portion in the pocket and also to displace the stud portion toward the trailing side of the pocket.

BRIEF SUMMARY OF THE INVENTION

In one aspect of the present invention, a drill bit has a body intermediate a shank and a working face, the working face comprising a plurality of blades armed on the working face and extending outwardly from the bit body. Each blade comprises at least one cutting element. The drill bit also has a jack element coaxial with an axis of rotation and extending out of an opening formed in the working face. A portion of the jack element is coated with a stop-off.

A superhard tip may be bonded to a distal end of the jack element. The superhard tip may comprise a material selected from the group consisting of diamond, polycrystalline diamond, natural diamond, synthetic diamond, vapor deposited diamond, silicon bonded diamond, cobalt bonded diamond, thermally stable diamond, infiltrated diamond, layered diamond, monolithic diamond, polished diamond, course diamond, fine diamond, cubic boron nitride, diamond impregnated matrix, diamond impregnated carbide, metal catalyzed diamond, or combinations thereof. The jack element may have a surface with a concave region. The jack may also comprise a material selected from the group consisting of steel, a refractory metal, carbide, tungsten carbide, cemented metal carbide, niobium, titanium, platinum, molybdenum, diamond, cobalt, nickel, iron, cubic boron nitride, and combinations thereof. The jack element may either be press fit into a steel sleeve bonded to the working face of the drill bit or it may be brazed into or onto the working face of the drill bit.

The stop-off may have a melting point higher than 1000 degrees Celsius. In some embodiments, the stop-off may be boron nitride. However, in other embodiments, the stop-off may comprise a material selected from the group comprising copper, nickel, cobalt, gold, silver, manganese, magnesium, palladium, titanium, niobium, zinc, phosphorous, boron, aluminum, cadmium, chromium, tin, silicon, tantalum, yttrium, metal oxide, ceramic, graphite, alumina or combinations thereof. The stop-off may be layered onto the jack element.

In another aspect of the invention, a method has steps for manufacturing a drill bit. A drill bit has a working face and an axis of rotation and a bit body intermediate a shank and the working face. A steel sleeve may be brazed into a pocket formed in the working face of the drill bit. A portion of the jack element may be covered with a stop-off. The stop-off may be applied to the jack element by a process of layering, dipping, spraying, brushing, flow coating, rolling, plating, cladding, silk screen printing, taping, masking or a combination thereof. The jack element may then be press fit into the steel sleeve and at least one cutting element may be brazed onto the working face adjacent the pressed fit jack element.

The stop-off may be boron nitride or it may comprise a material selected from the group comprising copper, nickel, cobalt, gold, silver, manganese, magnesium, palladium, titanium, niobium, zinc, phosphorous, boron, aluminum, cadmium, chromium, tin, silicon, tantalum, yttrium, metal oxide, ceramic, or combinations thereof. The material may be combined with an acrylic binder that is dissolved in a solvent in order to form the stop-off. The solvent may comprise xylene, toluene, butyl acetate, or a combination thereof.

The stop-off may be non-wetting to a braze used for bonding the cutting elements onto the working face or the jack element into a pocket formed in the working face. This may be beneficial in that the jack element may be protected from the braze during the manufacturing process. In some applications, the portion of the jack element may be covered with a stop-off comprising a wax or a lacquer. The jack element may have a concave region.

DETAILED DESCRIPTION

FIG. 1is a perspective diagram of an embodiment of a drill string100suspended by a derrick101. A bottom hole assembly102is located at a bottom of a bore hole103and includes a drill bit104. As the drill bit104rotates downhole, the drill string100advances farther into a subterranean formation105. The drill string100may penetrate a subterranean formations105that is soft or hard. The bottomhole assembly102and/or downhole components may include data acquisition devices which may gather data. The data may be sent to the surface via a transmission system to a data swivel106. The data swivel106may send the data to the surface equipment. Further, the surface equipment may send data and/or power to downhole tools and/or the bottomhole assembly102. U.S. Pat. No. 6,670,880, which is herein incorporated by reference for all that it contains, discloses a telemetry system that may be compatible with the present invention; however, other forms of telemetry may also be compatible such as systems that include mud pulse systems, electromagnetic waves, radio waves, and/or short hop. In some embodiments, no telemetry system is incorporated into the drill string.

In the embodiment ofFIG. 2, a drill bit104A has a bit body200A between a shank201A and a working face202A. A plurality of blades250A formed on the working face202A extend outwardly from the bit body200A, with each blade250A having at least one cutting element203A. A jack element204A extends out of an opening205A formed in the working face202A. The jack element204A may be formed of a material selected from the group consisting of a refractory metal, carbide, tungsten carbide, cemented metal carbide, niobium, titanium, platinum, molybdenum, diamond, cobalt, nickel iron, and cubic boron nitride. In the preferred embodiment, the stop-off may incldues boron nitride.

Referring now toFIG. 3, jack element204A is coaxial with an axis of rotation350A and extends out of the opening205A formed in the working face202A of the drill bit104A. A superhard tip300A is bonded to a distal end301A of the jack element204A and includes a material selected from the group consisting of diamond, polycrystalline diamond, natural diamond, synthetic diamond, vapor deposited diamond, silicon bonded diamond, cobalt bonded diamond, thermally stable diamond, infiltrated diamond, layered diamond, monolithic diamond, polished diamond, course diamond, fine diamond, cubic boron nitride, diamond impregnated matrix, diamond impregnated carbide and metal catalyzed diamond. The jack element204A is press fit into a steel sleeve302A brazed into a pocket303A formed in the working face202A of the drill bit104A. The working face202A includes the plurality of blades250A that are formed to extend outwardly from the bit body200A, each of which may have at least one cutting element203A. Preferably, the drill bit104A may have between three and seven blades250A. A plurality of nozzles305A may also be fitted into recesses306A formed in the working face202B.

During the manufacturing of the drill bit104A having a jack element204A, high temperatures may cause excess braze207A from the cutting elements203A proximate the jack element204A to melt and flow onto the jack element204A. It is believed that in some embodiments, the braze207may weaken the jack element204and contribute to damage of the jack element204in a downhole drilling operation. A portion206A of the jack element204A is coated with a stop-off in order to protect the jack element204A from the braze207A used to braze the cutting elements203A onto the plurality of blades250A. In some embodiments, the stop-off covers a portion206A of the jack element204A extending out of the opening205A formed in the working face202A. In other embodiments, the stop-off covers the whole jack element204A. The stop-off has a melting temperature higher than 1000 degrees Celsius. This is necessary because of the high temperatures the drill bit104A is exposed to during the manufacturing process. Preferably, the melting temperature of the stop-off is higher than a melting temperature of the braze207A.

FIG. 3adiscloses an embodiment of a drill bit104B with a jack element204B brazed directly to the bit body200B. A stop-off400B is coated onto the portion of the jack element204B below and above an opening205B of a pocket303B. The braze207B is allowed to bond a majority of the surface area of the jack element204B to the wall of the pocket303B, but not the portion of the jack element204B proximate the opening205B of the pocket303B. In some embodiments of the invention, the jack element204B may have a plurality of fluid holes. These holes may also be protected from braze material with a stop-off. In some embodiments, the stop-off may actually plug off the fluid holes during manufacturing.

FIGS. 4 through 7illustrate different embodiments of a jack element204C,204D,204E,204F extending out of an opening205C,205D,205E,205F formed in a working face202C,202D,202E,202F of a drill bit104C,104D,104E,104F. The jack element204C,204D,204E,204F is press fit into a steel sleeve302C,302D,302E,302F, the steel sleeve302C,302D,302E,302F being bonded to the working face202C,202D,202E,202F of the drill bit104C,104D,104E,104F. The steel sleeve302C,302D,302E,302F is brazed within a pocket303C,303D,303E,303F formed into the working face202C,202D,202E,202F. A stop-off400C,400D,400E,400F may cover a portion206C,206D,206E,206F of the jack element204C,204D,204E,204F. In some embodiments, the stop-off400C,400D,400E,400F comprises boron nitride. In other embodiments, the stop-off may comprise a material selected from the group consisting of copper, nickel, cobalt, gold, silver, manganese, magnesium, palladium, titanium, niobium, zinc, phosphorous, boron, aluminum, cadmium, chromium, tin, silicon, tantalum, yttrium, metal oxide, ceramic, graphite, and alumina. The stop-off400C,400D,400E,400F may be formed by combining an aforementioned material with an acrylic binder dissolved in a solvent. The solvent may comprise xylene, toluene, butyl acetate, hydrocarbons, or a combination thereof. The solvents and binders used in forming the stop-off400C,400D,400E,400F may be dependant on the method of applying the stop-off400C,400D,400E,400F as well as the material composition of the jack element204C,204D,204E,204F. The stop-off400C,400D,400E,400F may be non-wetting to a material used to braze the cutting elements203C,203D,203E,203F onto the working face202C,202D,202E,202F. It is believed that the stop-off400C,400D,400E,400F may protect the jack element204C,204D,204E,204F from thermal fluctuations during the manufacturing process. Thermal fluctuations may be caused by the molten braze contacting the jack element204C,204D,204E,204F, causing the jack element204C,204D,204E,204F to expand and constrict with the changing temperatures, thus weakening the jack element204C,204D,204E,204F.

In the embodiment ofFIG. 4, a stop-off400C may cover a portion206C of the jack element204C nearest the cutting elements203C. The portion206C of the jack element204C extending out of the drill bit may be more prone to contact with a braze from the cutting elements203C than other portions of the jack element204C.

However, as shown in the embodiment ofFIG. 5, it may be beneficial to cover a larger portion206D of the jack element204D with the stop-off400D to ensure that the portion206D of the jack element204D is protected.

In the embodiment ofFIG. 6, the stop-off400E may be applied to the jack element204E by taping. In other embodiments, the stop-off400E may be applied to the jack element204E by a process of layering, dipping, spraying, brushing, flow coating, rolling, plating, cladding, silk screen printing, masking or a combination thereof.

FIG. 7shows a jack element204F in which the stop-off400F is layered. In this embodiment, the stop-off400F may be thicker at one segment700F of the jack element204F than at another segment701F of the jack element204F. The amount of stop-off400F used to cover a portion206F of the jack element204F may vary along the jack element204F. Layers may be beneficial when the stop-off400F does not bond well to the portion206F of the jack element204F. In such a case, the undermost layer of the stop-off400F may form a good bond with the stop-off400F and the jack element204F.

FIGS. 8 through 11show various embodiments of a jack element204G. In some embodiments, a jack element204G,204H,204I,204J may have a surface800G,800H,800J with a concave region801G,801H,801J, as shown inFIGS. 8,9, and11. In such embodiments, it is believed that forces exerted on the jack element204G,204H,204J may be more evenly distributed throughout the jack element204G,204H,204J.

In the embodiment ofFIG. 8, a superhard tip300G may be bonded to a distal end301G of the jack element204G, the tip including a material selected from the group consisting of diamond, polycrystalline diamond, natural diamond, synthetic diamond, vapor deposited diamond, silicon bonded diamond, cobalt bonded diamond, thermally stable diamond, infiltrated diamond, layered diamond, monolithic diamond, polished diamond, course diamond, fine diamond, cubic boron nitride, diamond impregnated matrix, diamond impregnated carbide, and metal catalyzed diamond. The jack element204G may include a material selected from the group consisting of a refractory metal, carbide, tungsten carbide, cemented metal carbide, niobium, titanium, platinum, molybdenum, diamond, cobalt, nickel, iron, and cubic boron nitride.

In the embodiment ofFIG. 9, the jack element204H does not have a superhard tip. In this embodiment, the jack element204H includes surface800H with a concave region801H.

FIG. 10discloses an embodiment of a jack element204I with a superhard tip300I bonded to the distal end301I of the jack element204I. The superhard tip300I includes a flat-sided thick, sharp geometry as well as a curved interface1000I between the superhard tip300I and the jack element204I.

FIG. 11depicts a jack element204J with a superhard tip300J attached to the distal end301J of the jack element204J. Nodules1100J may be incorporated at the interface1000J between the superhard tip300J and the jack element204J, which may provide more surface area on the jack element204J to provide a stronger interface. This embodiment also shows a jack element204J having a surface800J with a concave region801J.

FIG. 12is a diagram of an embodiment of a method1200for manufacturing a drill bit. The method1200includes providing1201a drill bit with a working face and an axis of rotation and a bit body intermediate a shank and the working face. The method1200also includes brazing1202a steel sleeve into a pocket formed in the working face of the drill bit. The method1200further includes covering1203a portion of a jack element with a stop-off. The stop-off preferably comprises boron nitride. However, it may comprise copper, nickel, cobalt, gold, silver, manganese, magnesium, palladium, titanium, niobium, zinc, phosphorous, boron, aluminum, cadmium, chromium, tin, silicon, tantalum, yttrium, metal oxide, ceramic, or combinations thereof. Covering a portion of the jack element with a stop-off may include applying a wax or lacquer to the portion. The stop-off may be applied to the jack element by a process of layering, dipping, spraying, brushing, flow coating, rolling, plating, cladding, silk screen printing, taping, masking or a combination thereof. The method also includes press fitting1204the jack element into the steel sleeve and brazing1205at least one cutting element onto the working face adjacent the pressed fit jack element. The stop-off may be non-wetting to a material used in brazing the cutting elements onto the working face.

InFIG. 13, another method1200ais disclosed. The method1200amay comprise the steps of providing1201aa drill bit with a working face and an axis of rotation and a bit body intermediate a shank and the working face; covering1203aa portion of a jack element with a stop-off, and brazing1250athe jack element into the working face.