Patent ID: 12258815

DETAILED DESCRIPTION

The illustrations presented herein are not meant to be actual views of any particular earth-boring tool or cutting element, but are merely idealized representations employed to describe illustrative embodiments. The drawings are not necessarily to scale.

As used herein, the term “earth-boring tool” means and includes any type of bit or tool used for drilling during the formation or enlargement of a wellbore in a subterranean formation. For example, earth-boring tools include fixed-cutter bits, roller cone bits, percussion bits, core bits, eccentric bits, bicenter bits, reamers, mills, drag bits, hybrid bits (e.g., rolling components in combination with fixed cutting elements), and other drilling bits and tools known in the art.

As used herein, the term “substantially” in reference to a given parameter means and includes to a degree that one skilled in the art would understand that the given parameter, property, or condition is met with a small degree of variance, such as within acceptable manufacturing tolerances. By way of example, depending on the particular parameter, property, or condition that is substantially met, the parameter, property, or condition may be at least 90.0 percent met, at least 95.0 percent met, at least 99.0 percent met, at least 99.9 percent met, or even 100.0 percent met.

As used herein, “about” or “approximately” in reference to a numerical value for a particular parameter is inclusive of the numerical value and a degree of variance from the numerical value that one of ordinary skill in the art would understand is within acceptable tolerances for the particular parameter. For example, “about” or “approximately” in reference to a numerical value may include additional numerical values within a range of from 90.0 percent to 110.0 percent of the numerical value, such as within a range of from 95.0 percent to 105.0 percent of the numerical value, within a range of from 97.5 percent to 102.5 percent of the numerical value, within a range of from 99.0 percent to 101.0 percent of the numerical value, within a range of from 99.5 percent to 100.5 percent of the numerical value, or within a range of from 99.9 percent to 100.1 percent of the numerical value.

As used herein, the term “and/or” means and includes any and all combinations of one or more of the associated listed items.

Referring toFIG.1, a perspective view of an earth-boring tool10in the form of rotary drill bit is shown. The earth-boring tool10may have blades20in which a plurality of cutting elements100may be secured. The cutting elements100may have a cutting table101with a cutting face102which may form the cutting profile of the earth-boring tool10. The cutting elements100may also include a substrate108configured to support the cutting table101. The substrate108may be secured to the blade20within a cutting element pocket formed in the blade20. For example, each cutting element may be welded, soldered, brazed, etc., to the blade20within a cutting element pocket formed therein.

The earth-boring tool10may rotate about a longitudinal axis of the earth-boring tool10during use thereof. When the earth-boring tool10rotates, the cutting face102of the cutting elements100may contact the earth formation and remove material therefrom. The material removed by the cutting faces102may then be removed through the junk slots40. The earth-boring tool10may include nozzles50, through which fluid, such as water or drilling mud, may be introduced into the area around the blades20to aid in removing the sheared material and other debris from the area around the blades and/or to cool the cutting elements100and the blades20.

FIG.2illustrates a perspective view of a rotatable cutting element100in accordance with embodiments of the present disclosure. The rotatable cutting element100may comprise the cutting table101with the cutting face102and a substrate108. The cutting table101may be formed from a polycrystalline material, such as, for example, polycrystalline diamond or polycrystalline cubic boron nitride. The rotatable cutting element100may be secured to the earth-boring tool10(FIG.1) by fixing the exterior surface of the substrate108to the earth-boring tool10. This is commonly achieved through a brazing process. The cutting table101is configured to rotate relative to at least a portion of the substrate108, such that the exterior surface of the108may be secured to the earth-boring tool10and the cutting table101may rotate relative to the earth-boring tool10.

FIG.3illustrates a simplified cross-sectional schematic illustration of the rotatable cutting element100ofFIG.2. The rotatable cutting element100may include a stationary portion302and a rotatable portion304. The stationary portion302may include a sleeve306. The sleeve306may form a portion of the substrate108including the outer surface of the substrate108that is secured to the earth-boring tool10(FIG.1). The sleeve306defines a cavity322into which a portion of the rotatable portion304is disposed.

The rotatable portion304may include a spindle310configured to extend into the cavity322defined in the sleeve306. The rotatable portion304may also include a shoulder308configured to extend laterally over an upper end surface of the sleeve306and form an interface318between the upper end surface of the sleeve306and a lower surface of the shoulder308on the rotatable portion304. The spindle310and a portion of the shoulder308form an additional rotatable portion304of the substrate108(and the cutting element100). As described above, the cutting table101is fixed to the rotatable portion304, and will rotate together with the rotatable portion304.

The substrate108and the cutting table101may each be formed from different hard materials. For example, the cutting table101may be formed from a super-hard material, such as polycrystalline diamond or polycrystalline cubic boron nitride. The components of the substrate108may be formed from another hard material suitable for use in an earth-boring operation, such as a metal, an alloy (e.g., steel), a ceramic-metal composite material (e.g., cobalt-cemented tungsten carbide), or combinations thereof.

The spindle310of the rotatable portion304and the cavity322of the stationary portion302may have substantially complementary shapes. For example, the cavity322and the spindle310may each have a cylindrical shape and the spindle310may have a major dimension (e.g., diameter or radius) that is slightly less than a major dimension of the cavity322, such that the spindle310may rotate within the cavity322with little to no friction. The rotatable portion304and the stationary portion302may be substantially coaxial, such that each of the stationary portion302and the rotatable portion304may have a same longitudinal axis320, which may also be the rotational and longitudinal axis320of the rotatable cutting element100. The sleeve306may substantially surround the spindle310, which may substantially prevent radial movement of the rotatable portion304relative to the stationary portion302to maintain the substantially coaxial relationship between the stationary portion302and the rotatable portion304.

The rotatable portion304may be retained within the sleeve306by a retaining element312that may mechanically engage with each of a retaining face316of the sleeve306and a retaining groove314of the spindle310so as to retain the rotatable portion304within the stationary portion302. In some embodiments, the retaining element312is formed as a ring having an opening between two ends of the ring, such that the ring has a C-shape. The opening may facilitate compression and expansion of the ring. For example, the ring may be expanded by applying a radially outward force increasing a size of the opening, such as to fit the ring around the spindle310. The ring may be compressed by applying a radially inward force to decrease a size of the opening, such as to compress the ring into the retaining groove314for assembly or disassembly as described below. The retaining element312may be formed from a spring-like material having a large yield strength and a large elastic modulus, such that the retaining element312can be deformed (e.g., compressed or expanded) and will return to its original shape, such as the C-shaped ring. The retaining element312may be configured to limit axial movement of the rotatable portion304relative to the stationary portion302. For example, the retaining element312may be configured to allow limited axial movement between the rotatable portion304and the stationary portion302while maintaining sufficient space there between to establish a relatively low friction interface between the rotatable portion304and the stationary portion302to facilitate rotating the rotatable portion304relative to the stationary portion302during operation.

To facilitate assembly and/or disassembly of the rotatable cutting elements100, as well as rotation of the rotatable portion304relative to the stationary portion302, clearance may be included at each interface, such as between the retaining groove314and the retaining element312, between the retaining element312and the retaining face316. A gap at the interface318between the upper end surface of the sleeve306and a lower surface of the shoulder308results from the combination of the clearances at each interface. The individual clearances may be in a range from about 0.005 inches (0.127 mm) to about 0.05 inches (1.27 mm), such as between about 0.005 inches (0.127 mm) and about 0.02 inches (0.508 mm). After the rotatable cutting element100is assembled, the individual clearances may combine (e.g., through clearance stack-up), to create a larger overall clearance between the upper end surface of the sleeve306and a lower surface of the shoulder308. This may allow large amounts of axial movement between the rotatable portion304and the stationary portion302. Large amounts of axial movement can result in debris entering the internal spaces between the stationary portion302and the rotatable portion304, such as at the interface318or within the cavity322. This debris may cause damage to the interface318, internal surfaces within the cavity322, spindle310, and other parts of the rotatable cutting elements100, which may reduce the operational life of the rotatable cutting element100. In other cases, the debris may prevent the rotatable portion304from rotating as intended relative to the stationary portion302, which may negate the benefits of a rotatable cutting element. Thus, limiting the axial movement of the rotatable portion304relative to the stationary portion302may increase an operational life of the associated rotatable cutting element100.FIGS.4A through7illustrate different examples of retaining elements312and interfaces between the retaining elements312and the spindle310and the sleeve306.

FIGS.4A and4Billustrate enlarged views of an interface between a retaining element402and the retaining portions of the rotatable portion304and the stationary portion302. As illustrated inFIG.4A, an inner wall408of the stationary portion302may extend radially away from the rotatable portion304in a plane passing through the longitudinal axis320(FIG.3), such that the cross-sectional area of the cavity322is larger in a lower retaining region410than in an upper region of the cavity322. As shown inFIG.4B, the inner wall408in the retaining region410may include a retaining face412and a biasing face406. The biasing face406may extend at an angle A relative to the longitudinal axis320(FIG.3) of the cutting element100. The retaining face412extends in a direction substantially transverse to the longitudinal axis320(FIG.3) of the cutting element100and may be configured to interface with a top surface414of the retaining element402to substantially prevent the rotatable portion304from moving axially beyond the interface between the top surface414of the retaining element402and the retaining face412.

The biasing face406may be configured to interface with the retaining element402by gradually increasing or decreasing a frictional force on a biasing interface surface404of the retaining element402as the rotatable portion304is urged in an axial direction along the longitudinal axis320(FIG.3). This may limit the axial motion of the rotatable portion304before the top surface414of the retaining element402reaches the retaining face412.

In some embodiments, the angle A of the biasing face406is selected to provide a large change in frictional force over a relatively small change in axial position. For example, the angle A may be between about 45° and about 89°, such as between about 60° and about 89°, or between about 80° and about 89°. The biasing interface surface404may extend at an angle B relative to the longitudinal axis320(FIG.3). The angle A of the biasing face406and the angle B of the biasing interface surface404may be similar. The biasing face406and the biasing interface surface404extending at similar angles A and B, may result in an increase in contact area between the biasing interface surface404and the biasing face406. The angle B of the biasing interface surface404may be substantially the same as the angle A of the biasing face406, such as within +/−20° of the angle A of the biasing face406, or within +/−10° of the angle A of the biasing face406, or within about +/−5° of the angle A of the biasing face406.

As described above, the retaining element402may be formed from a substantially rigid spring-like material capable of withstanding the high temperatures and pressures in a downhole environment while maintaining a high yield strength and having a high modulus of elasticity. When assembled the retaining element402may be elastically compressed into the retaining groove314. Once the retaining element402and retaining groove314are substantially axially aligned with the retaining region410, the retaining element402is configured to expand or bias in a radial direction away from the longitudinal axis320(FIG.3) to return to its original, un-compressed shape. For example, the retaining element402may be formed from a metal or metal alloy, such as steel, iron, stainless steel, nickel based alloys, chromium, etc., or a high temperature polymer, such as polytetrafluoroethylene (PTFE). The original, un-compressed shape of the retaining element402may be sufficiently large, that the retaining element402may extend until the biasing interface surface404of the retaining element402contacts the biasing face406of the stationary portion302. As the retaining element402extends, the angles A and B of the biasing face406and the biasing interface surface404may cause the rotatable portion304to move axially into the stationary portion302. The angles A and B may be selected such that the retaining element402may fully extend before the shoulder308(FIG.3) reaches the interface318(FIG.3), such that a clearance is maintained between the upper end surface of the sleeve306(FIG.3) and a lower surface of the shoulder308(FIG.3) to facilitate rotation of the rotatable portion304relative to the stationary portion302. The interface318(FIG.3) between the shoulder308(FIG.3) of the rotatable portion304and the stationary portion302may limit the axial movement of the rotatable portion304into the stationary portion302, while the interface between the biasing interface surface404of the retaining element402and the biasing face406of the stationary portion302may limit the axial movement of the rotatable portion304out of the stationary portion302.

FIGS.5A and5Billustrate enlarged views of another embodiment of the interface between a retaining element502and the retaining portions of the rotatable portion304and the stationary portion302. As illustrated inFIGS.5A and5B, an inner wall508of the stationary portion302extends radially away from the rotatable portion304in a plane passing through the longitudinal axis320(FIG.3), such that the cross-sectional area of the cavity322is larger in a lower retaining region510than in an upper region of the cavity322. As shown inFIG.5B, inner wall408in the retaining region410includes a biasing face506. The biasing face506extends at an angle A relative to the longitudinal axis320(FIG.3) of the cutting element100. The biasing face506may be configured to interface with the retaining element502by gradually increasing or decreasing a frictional force on a biasing interface surface504of the retaining element502as the rotatable portion304moves in an axial direction.

In some embodiments, the angle A of the biasing face506is selected to provide a large change in frictional force over a relatively small change in axial position. For example, the angle A may be between about 45° and about 89°, such as between about 60° and about 89°, or between about 80° and about 89°. The biasing interface surface504may extend at an angle B relative to the longitudinal axis320(FIG.3). The angle A of the biasing face506and the angle B of the biasing interface surface504may be similar. The biasing face506and the biasing interface surface504extending at similar angles A and B, may result in an increase in contact area between the biasing interface surface504and the biasing face506. The angle B of the biasing interface surface504may be substantially the same as the angle A of the biasing face506, such as within +/−20° of the angle A of the biasing face506, or within +/−10° of the angle A of the biasing face506, or within about +/−5° of the angle A of the biasing face506.

As described above, the retaining element502may be formed from a substantially rigid spring-like material capable of withstanding the high temperatures and pressures in a downhole environment while maintaining a high yield strength and having a high modulus of elasticity. When assembled the retaining element502may be elastically compressed into the retaining groove314. Once the retaining element502and retaining groove314are substantially radially aligned with the retaining region510, the retaining element502is configured to expand or bias in a radial direction away from the longitudinal axis320(FIG.3) to return to its original, un-compressed shape. For example, the retaining element502may be formed from a metal, such as steel, iron, stainless steel, nickel based alloys, chromium, etc., or a high temperature polymer, such as polytetrafluoroethylene (PTFE). The original, un-compressed shape of the retaining element502may be sufficiently large, that the retaining element502may extend until the biasing interface surface504of the retaining element502contacts the biasing face506of the stationary portion302. As the retaining element502extends the angles A and B of the biasing face506and the biasing interface surface504may cause the rotatable portion304to move axially into the stationary portion302. The angles A and B may be selected such that the retaining element502may fully extend before the shoulder308(FIG.3) reaches the interface318(FIG.3), such that a clearance is maintained between the upper end surface of the sleeve306(FIG.3) and a lower surface of the shoulder308(FIG.3) to facilitate rotation of the rotatable portion304relative to the stationary portion302. The interface318(FIG.3) between the shoulder308(FIG.3) of the rotatable portion304and the stationary portion302may limit the axial movement of the rotatable portion304into the stationary portion302, while the interface between the biasing interface surface504of the retaining element502and the biasing face506of the stationary portion302may limit the axial movement of the rotatable portion304out of the stationary portion302.

As illustrated inFIGS.5A and5B, some embodiments do not include a retaining face. The exclusion of the retaining face may facilitate the removal of the rotatable portion304from the stationary portion302. For example, an axial force may be applied to the rotatable portion304in a direction out of the stationary portion302. As the rotatable portion304moves axially out of the stationary portion302, the interface between the biasing interface surface504of the retaining element502and the biasing face506of the stationary portion302may cause the retaining element502to be compressed into the retaining groove314of the rotatable portion304. The axial force may be sufficient to cause the retaining element502to retract fully into the retaining groove314, such that the retaining element502has an outer diameter less than or equal to a diameter of the inner wall508in the region axially above the retaining region510. This may facilitate removing the rotatable portion304from the stationary portion302, such as for repair, reprocessing or replacement.

FIGS.6A and6Billustrate enlarged views of another embodiment of the interface between a retaining element602and the retaining portions of the rotatable portion304and the stationary portion302. As illustrated inFIGS.6A and6B, an inner wall608of the stationary portion302extends radially away from the rotatable portion304increasing a cross-sectional area of the cavity322to form a retaining region610. The inner wall608in the retaining region610includes a retaining face604. The retaining face604extends in a direction substantially transverse to the longitudinal axis320(FIG.3) of the cutting element100and may interface with a top surface606of the retaining element602to substantially prevent the rotatable portion304from moving axially beyond the interface between the top surface606of the retaining element602and the retaining face604.

In some embodiments, the retaining element602is formed from a shape memory alloy. The shape memory alloy is a metal alloy configured to change shape when exposed to a triggering condition, such as a triggering temperature. Shape memory alloys may include Nickel Titanium alloys, such as Nitinol (NiTi), Nickel Titanium Cobalt (NiTi—Co), Nickel Titanium Copper (NiTi—Cu), Nickel Titanium Chromium (NiTi—Cr), and Nickel Titanium Vanadium (NiTi—V). The retaining element602may have a ring shape, such as a C-shaped ring, similar to the embodiments described above. The retaining element602may be trained to move into a conical ring shape when triggered, as illustrated inFIG.6B, such that the retaining element602may act as a biasing element, such as a spring or Belleville washer. The conical shape may cause the retaining element602to extend between the retaining face604of the stationary portion302and an inner face612of the retaining groove314with the top surface606of the retaining element602forming an acute angle (e.g., an angle between about 5° and about 30°, such as between about 10° and about 20°) relative to the respective faces604,612.

The retaining element602may act as a biasing element, such that the resting shape of the retaining element602may apply an inward axial force to the rotatable portion304and any outward axial movement of the rotatable portion304may be resisted by a deformation force in the retaining element602. Thus, the interface318(FIG.3) between the shoulder308(FIG.3) of the rotatable portion304and the stationary portion302may limit the axial movement of the rotatable portion304into the stationary portion302, while the deformation force in the602coupled with the interfaces between the retaining element602and the retaining face604and the retaining element602and the inner face612of the314may limit the axial movement of the rotatable portion304out of the stationary portion302.

The shape memory alloy of the retaining element602may be configured to trigger at a temperature higher than ambient temperature (e.g., about 25° C.). In some embodiments, the retaining element602is configured to trigger at or around temperatures that are typical of a downhole environment. For example, the retaining element602may be configured to trigger at a temperature between about 100° F. and about 900° F., such as between about 150° F. and about 600° F., or between about 300° F. and about 350° F. In some embodiments, the cutting element100will be assembled and a triggering temperature will be applied to the cutting element100as part of the assembly process. In another embodiment, the cutting element100will be assembled and the downhole environment will be relied on to provide the triggering temperature, such that the retaining element602will change shape to the conical biasing shape after the cutting element100is inserted into the wellbore. In a further embodiment, the shape memory alloy of the retaining element602may be configured to trigger at around or slightly below ambient temperature, so that the retaining element602may be cooled substantially below ambient in a freezer or by dry ice, inserted and triggered by ambient heat of the drill bit.

A rotating cutting element100including a shaped memory alloy retaining element602may be assembled by first training the shaped memory alloy retaining element602to the desired shape (e.g., conical shape) at the desired trigger temperature. Typically, a shaped memory alloy is trained by securing the alloy in the desired shape and holding the alloy in that shape at the desired temperature for a time period, such as between about five minutes and an hour, or between about ten minutes and thirty minutes. After the time period the shaped memory alloy is rapidly cooled.

When the temperature of the retaining element602is reduced or lowered to a temperature below the trigger temperature, such as ambient temperature, the retaining element602may then be compressed into the retaining groove314of the rotatable portion304, such as by reducing a size of the opening between the ends of a C-shaped ring. The retaining element may be deformed to a flat disc or ring shape. Additional tooling such as a ring compressor may be used to compress the retaining element602fully into the retaining groove314, such that the rotatable portion304may be inserted into the cavity322defined in the stationary portion302. The rotatable portion304may be axially inserted or disposed into the cavity322with the inner wall608securing the retaining element602in the retaining groove314until the retaining groove314and retaining element602reach the retaining region610.

In the retaining region610, the inner wall608extends radially away from the rotatable portion304, such that the retaining element602may extend away from the retaining groove314into the retaining region610. In some embodiments, the retaining region610may also include a biasing face (e.g., biasing face406), as illustrated inFIGS.4A and4Band described above. In some embodiments, the cutting element100is then manually heated, such as in a furnace, kiln, or with a heat gun or other heating device, to a temperature above the triggering temperature, such that the retaining element602returns to the desired trained shape and biases the rotatable portion304into the stationary portion302. In other embodiments, the cutting element100is stored at ambient temperatures and the cutting element100is transported to the worksite without triggering the shaped memory alloy of the retaining element602. The cutting element100is then tripped into a borehole on an earth-boring tool where the heat of the downhole environment and/or heat generated by friction triggers the shaped memory alloy into the desired or trained shape, such that the retaining element602biases the rotatable portion304into the stationary portion302further limiting the axial movement of the rotatable portion304.

Embodiments of the present disclosure may extend the operating life of cutting elements by limiting damage to the cutting elements and facilitating rotation of the rotatable cutter by substantially preventing binding, clogging, and other debris related impediments to the free rotation of the rotatable cutting element. This may provide a cutting element with improved wear characteristics of a cutting surface that may result in a longer service life for the rotatable cutting elements. Extending the life of the rotatable cutting elements may in turn, extend the life of the earth-boring tool to which they are attached. Replacing earth-boring tools or even tripping out an earth-boring tool to replace worn or damaged cutters is a large expense for earth-boring operations. Often earth-boring tools are on a distal end of a drill string that can be in excess of 40,000 feet long. The entire drill string must be removed from the borehole to replace the earth-boring tool or damaged cutters. Extending the life of the earth-boring tool may result in significant cost savings for the operators of an earth-boring operation.

The embodiments of the disclosure described above and illustrated in the accompanying drawing figures do not limit the scope of the invention, since these embodiments are merely examples of embodiments of the invention, which is defined by the appended claims and their legal equivalents. Any equivalent embodiments are intended to be within the scope of this disclosure. Indeed, various modifications of the present disclosure, in addition to those shown and described herein, such as alternative useful combinations of the elements described, may become apparent to those skilled in the art from the description. Such modifications and embodiments are also intended to fall within the scope of the appended claims and their legal equivalents.