Embodiments of the present disclosure relate to earth-boring tools including bearing element assemblies, and related methods.
Earth-boring tools are used to form boreholes (e.g., wellbores) in subterranean formations. Such earth-boring tools include, for example, drill bits, reamers, mills, etc. For example, a fixed-cutter earth-boring rotary drill bit (often referred to as a “drag” bit) generally includes a plurality of cutting elements secured to a face of a bit body of the drill bit. The cutters are fixed in place when used to cut formation materials. A conventional fixed-cutter earth-boring rotary drill bit includes a bit body having generally radially projecting and longitudinally extending blades. During drilling operations, the drill bit is positioned at the bottom of a well borehole and rotated.
A plurality of cutting elements is positioned on each of the blades. The cutting elements commonly comprise a “table” of superabrasive material, such as mutually bound particles of polycrystalline diamond, formed on a supporting substrate of a hard material, such as cemented tungsten carbide. Such cutting elements are often referred to as “polycrystalline diamond compact” (PDC) cutting elements or cutters. The plurality of PDC cutting elements may be fixed within cutting element pockets formed in rotationally leading surfaces of each of the blades. Conventionally, a bonding material, such as a braze alloy, may be used to secure the cutting elements to the bit body.
Some earth-boring tools may also include bearing elements that may limit the depth-of-cut (DOC) of the cutting elements, protect the cutting elements from excessive contact with the formation, enhance (e.g., improve) lateral stability of the tool, or perform other functions or combinations of functions. The bearing elements conventionally are located entirely rotationally behind associated leading cutting elements to limit DOC as the bearing elements contact and ride on an underlying earth formation, although bearing elements rotationally leading cutting elements are also known.
In one aspect of the disclosure, an earth-boring tool includes a body with a pocket in a leading end thereof for accepting at least a portion of a bearing element assembly. A bearing element assembly is disposed within the pocket, and the bearing element assembly includes a retaining element at least partially disposed in a groove in a sidewall of the pocket and a bearing element. The bearing element includes a distal end having a bearing surface, a proximal end, and a side surface between the distal end and the proximal end. The side surface includes a feature configured to abut the retaining element, and mechanical interference between the feature and the retaining element axially retains the bearing element within the pocket.
In another aspect of the disclosure, an earth-boring tool includes a body with a threaded receptacle in a leading end thereof for accepting at least a portion of a bearing element assembly. A bearing element assembly is disposed within the threaded receptacle, and the bearing element assembly may include a holder with a receptacle at a distal end thereof for receiving a bearing element, a threaded outer surface at a proximal end thereof for engagement with the threaded receptacle in the body of the earth-boring tool, and at least one feature proximate the distal end of the holder configured to interface with a tool adapted to apply torque to the holder.
In yet another aspect of the disclosure, a method of replacing a bearing element of an earth-boring tool includes disengaging a mechanical retention device retaining a first bearing element within a pocket in a body of the earth-boring tool, removing the first bearing element from the pocket, placing a second bearing element in the pocket, wherein the second bearing element comprises at least one of a shape of a bearing surface and an exposure of a bearing surface different from the first bearing element, and engaging the mechanical retention device to retain the second bearing element within the pocket.
While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the present invention, various features and advantages of disclosed embodiments may be more readily ascertained from the following description when read with reference to the accompanying drawings, in which:
The illustrations presented herein are not actual views of any particular material, bearing element assembly, or earth-boring tool, but are merely idealized representations employed to describe embodiments of the present disclosure. Additionally, elements common between figures may retain the same numerical designation.
As used herein, the term “bearing element” means an element configured to be mounted on a body of an earth-boring tool, such as a drill bit, and to rub against a formation as the body of the earth-boring tool is rotated within a wellbore. Bearing elements include, for example, what are referred to in the art as depth-of-cut (DOC) control elements. Bearing elements do not include conventional PDC cutting elements configured to cut formation material by a shearing mechanism.
The body 104 of the earth-boring tool 100 may be secured to a shank 108 having a threaded connection portion 110, which may conform to industry standards, such as those promulgated by the American Petroleum Institute (API), for attaching the earth-boring tool 100 to a drill string (not shown).
The body 104 may include internal fluid passageways that extend between fluid ports 112 at the face of the body 104 and a longitudinal bore that extends through the shank 108 and partially through the body 104. Nozzle inserts 114 may be secured within the fluid ports 112 of the internal fluid passageways. The body 104 may further include a plurality of blades 116 that are separated by fluid courses 118, which may be referred to in the art as “junk slots.” In some embodiments, the body 104 may include gage wear plugs 120, wear knots 122, or both.
Each bearing element assembly 106 may be positioned on a blade 116 to rotationally trail at least one cutting element 102, as shown in
Bearing element assemblies like the bearing element assemblies 106 may serve to limit the depth-of-cut (DOC) of the cutting elements 102. Drilling characteristics of a particular bit, such as DOC, may depend on exposure of bearing surfaces of the bearing element assemblies 106. Thus, bearing element assemblies having different exposures may impart different drilling characteristics to a particular bit design. Conventionally, bearing elements similar to bearing element assemblies 106 may be brazed into pockets in the earth-boring tool 100. Replacement of brazed bearing elements typically requires the earth-boring tool 100 to be returned to a manufacturing facility where the bit body may undergo heat cycles during a brazing process. Embodiments of the present disclosure relate to earth-boring tools and bearing element assemblies that enable replacement of the bearing element assemblies in the field of use.
Referring now to
The bearing element 201 may comprise a proximal end 210 and a side surface 212 between the distal end 206 and the proximal end 210. The side surface 212 may also be characterized as a sidewall. In the embodiment shown in
The pocket 202 may have a transverse cross-sectional shape generally similar to the transverse cross-sectional shape of the side surface 212 of the bearing element assembly 200. In some embodiments, the side surface 212 may be sized such that the bearing element 201 fits within the pocket 202 with an interference fit. In other embodiments, the side surface 212 and the pocket 202 may be sized such that a clearance exists between the side surface 212 of the bearing element 201 and a sidewall 203 of the pocket 202. Such a clearance may be provided intentionally to ease insertion and removal of the bearing element assembly 200, or the clearance may be the result of inaccuracy inherent in the manufacturing process.
The sidewall 203 of the pocket 202 may include a groove 214 in a plane generally normal to a central axis Ac of the pocket 202. The groove 214 may be substantially annular. A retaining element 216 may be at least partially disposed within the groove 214. The retaining element 216 may also be characterized as a mechanical retention device. As a non-limiting example, the retaining element 216 may have a substantially circular transverse cross-sectional shape (i.e., in the cross-section of
The side surface 212 of the bearing element 201 may include a feature against which a portion of the retaining element 216 may abut to retain the bearing element 201 within the pocket 202. For example, a portion of the retaining element 216 may extend from the groove 214 and into a recess 218 in the side surface 212 of the bearing element 201. Mechanical interference between the retaining element 216, a surface of the blade 204 within the groove 214, and a portion 220 of the side surface 212 of the bearing element 201 within the recess 218 may retain the bearing element 201 within the pocket 202.
One or more removal access holes may extend through an exterior surface of the blade 204 and intersect at least a portion of the pocket 202. For example, one or more channels 222 may be disposed in the sidewall 203 of the pocket 202. For example, the one or more channels 222 may extend into a surface of the blade 204 in a direction substantially parallel to the central axis Ac of the pocket 202, and may intersect the pocket 202 adjacent a portion of the side surface 212 of the bearing element assembly 200. The one or more channels 222 may be configured to accept a removal tool used to facilitate removal of the bearing element assembly 200 from the pocket 202 of the blade 204, as will be described in greater detail below. The one or more channels 222 may be spaced equidistantly about a circumference of the pocket 202. For example, in the embodiment of
The side surface 212 of the bearing element 201 may include a notch 224 positioned adjacent the one or more channels 222. As a non-limiting example, the notch 224 may have an annular shape, i.e., the notch 224 may extend around a circumference of the side surface 212 of the bearing element 201.
To remove the bearing element 201 from the pocket 202 of the blade 204, an operator may insert a tool (e.g., a prying tool, such as a pry bar or flat-bladed screwdriver, or a pulling tool, such as a multi jawed puller) into the one or more channels 222, such that a portion of the tool rests within the notch 224 in the side surface 212. Using the tool, the operator may apply a force F generally parallel to the central axis Ac of the pocket 202, e.g., by prying or pulling against the bearing element 201 within the notch 224. Under the applied force F, a portion of the side surface 212 within the recess 218 may bear against the retaining element 216 and urge the retaining element 216 to expand circumferentially into the groove 214. The retaining element 216 may move free of the recess 218 to enable removal of the bearing element 201 from the pocket 202. The retaining element 216 may be left within the groove 214, or may be circumferentially compressed and removed from the groove 214 and the pocket 202. A replacement retaining element may be inserted into the pocket 202 and into the groove 214.
A replacement bearing element may be inserted into the pocket 202 by the operator. As shown in
When necessary, the operator may replace the bearing element 201 with another bearing element having different characteristics, e.g., a different exposure or shape of the bearing surface 208, to impart to the earth-boring tool 100 (
Referring now to
A feature such as a flange 316 may extend from the side surface 314. As a non-limiting example, the flange 316 may be substantially annular. The pocket 302 may be shaped to receive the flange 316. For example, the pocket 302 may include a first portion 318 having a first diameter D1, the first portion 318 extending a first depth Dp1 into the blade 304 along a central axis Ac of the pocket 302. The pocket 302 may have a second portion 320 having a second diameter D2, the second portion 320 extending a second depth Dp2 into the blade 304 along the central axis Ac. The first diameter D1 may be greater than the second diameter D2, and the first depth Dp1 may be less than the second depth Dp2. The first diameter D1 may be substantially the same as a diameter of the flange 316, and the flange 316 may be substantially received within the first portion 318 of the pocket 302.
The first portion 318 of the pocket 302 may include a groove 322 in a sidewall thereof. A retaining element 324 may be disposed at least partially within the groove 322. In this embodiment, the groove 322 is substantially annular in shape. The retaining element 324 may abut a portion of the flange 316 to retain the bearing element 301 within the pocket 302. As a non-limiting example, the retaining element 324 may be a spiral snap ring. In other embodiments, the retaining element may be an internal split snap ring (which may be referred to in the art as a “circlip”).
One or more removal access holes may extend through an exterior surface of the blade 304 and intersect the pocket 302 adjacent a portion of the bearing element 301. For example, the one or more removal access holes may be defined by one or more channels 326 disposed in a sidewall 303 of the pocket 302. The one or more channels 326 may extend from an exterior surface of the blade 304 into the blade 304 in a direction generally parallel to the central axis Ac of the pocket 302. The one or more channels 326 may intersect the first portion 318 of the pocket 302 adjacent a portion of the flange 316. The one or more channels 326 may be equidistantly spaced around a circumference of the pocket 302. For example, three channels 326 may be spaced about one hundred twenty degrees (120°) apart.
To remove the bearing element 301, an operator may remove the retaining element 324 by, e.g., prying an end of the retaining element 324 out of the groove 322 and gradually prying the retaining element 324 from the groove 322 around a circumference thereof in the case of a spiral snap ring. As another example, the operator may use snap ring pliers or a similar tool to circumferentially contract a split ring and remove it from the groove 322. A removal tool such as a prying or pulling tool as described above may be inserted into the one or more channels 326, such that a portion of the removal tool contacts a proximal surface 328 of the flange 316. Using the tool, the operator may apply a force F generally along the central axis Ac, e.g., by prying or pulling, to release the bearing element 301 from the pocket 302.
Referring now to
To remove the bearing element 401 from the pocket 402, an operator may insert a portion of a tool 420 into the bore 406. For example, the tool 420 may be a tool with an elongated shank at a working end, such as a pin punch. The operator may drive the tool 420 into the bore 406 until the tool abuts the proximal surface 410 of the bearing element 401. Driving the tool 420 further into the bore 406 may cause the tool 420 to bear against the proximal surface 410 of the bearing element 401 and force the bearing element 401 from the pocket 402.
In some embodiments of the present disclosure, bearing element assemblies may include a bearing element disposed within a receptacle of a holder. The holder may include a mechanical retention device (e.g., a threaded outer surface configured to interface with a threaded receptacle in a blade of an earth-boring tool 100 (
For example, referring now to
In
A mechanical locking device 520 may be disposed between a distal surface 522 of the sleeve 514 and a proximal surface 524 of the holder 504. The mechanical locking device 522 may include, as non-limiting examples, a locking washer such as a split washer or star washer, a Belleville (i.e., conical) washer, or other locking washers.
Referring now to
The holder 604 may include a conical portion 620 between the distal end 606 and the proximal end 610. The sleeve 614 may include a corresponding conical surface 622 on an inner diameter at a location distal to the threaded inside diameter 616. Contact between the conical portion 620 of the holder 604 and the conical surface 622 of the sleeve 614 may enhance (e.g., increase) a frictional force between the holder 604 and the sleeve 614, preventing the holder 604 from rotating relative to the sleeve 614 and consequently loosening from the sleeve 614.
Referring now to
The threaded receptacle 702 of the blade 704 may include a pocket 708 and a sleeve 710 disposed in the pocket 708. The sleeve 710 may be similar to sleeves 514 and 614 described above with reference to
The pocket 708 may include a slot 712 adjacent an outside diameter 718 of the sleeve 710. The slot 712 may extend through the blade 704 to expose a portion of the outside diameter 718 of the sleeve 710, as shown in
To remove the bearing element assembly 700 from the blade 704, an operator may place a tool, e.g., a socket wrench, over the wrench flats 706 and apply a rotational force with the tool to the bearing element assembly 700. The operator may remove the bearing element assembly 700 from the sleeve 710 and pocket 708. The operator may place a replacement bearing element assembly 700 within the pocket 708 and use the tool to tighten threads (e.g., threaded shank 512, 612 of holders 504, 604 shown in
The threaded outer surface 808 may be configured substantially identically to an outer surface of a nozzle insert 114 (
Referring now to
Referring now to
Additional non-limiting example embodiments of the disclosure are set forth below.
An earth-boring tool, comprising: a body comprising a pocket in a leading end thereof for accepting at least a portion of a bearing element assembly; and a bearing element assembly disposed within the pocket, the bearing element assembly comprising: a retaining element at least partially disposed in a groove in a sidewall of the pocket; and a bearing element comprising: a distal end having a bearing surface; a proximal end; and a side surface between the distal end and the proximal end, the side surface comprising a feature configured to abut the retaining element, wherein mechanical interference between the feature and the retaining element axially retains the bearing element within the pocket.
The earth-boring tool of Embodiment 1, further comprising at least one removal access hole extending through an exterior surface of the body and intersecting the pocket, wherein the at least one removal access hole is configured to receive a removal tool.
The earth-boring tool of Embodiment 2, wherein the at least one removal access hole is defined by a channel in the sidewall of the pocket and extending in a direction substantially parallel to a central axis of the pocket.
The earth-boring tool of Embodiment 3, wherein the at least one removal access hole comprises a plurality of channels spaced equidistantly around the sidewall of the pocket.
The earth-boring tool of Embodiment 3 or Embodiment 4, wherein the side surface of the bearing element comprises a notch adjacent the channel.
The earth-boring tool of any one of Embodiments 2 through 5, wherein the at least one removal access hole comprises a bore extending through an exterior surface of the body and intersecting the pocket.
The earth-boring tool of Embodiment 6, wherein the bore intersects the pocket adjacent a proximal surface of the bearing element.
The earth-boring tool of any one of Embodiments 1 through 7, wherein the protrusion comprises a substantially annular flange extending laterally from the side surface of the bearing element.
The earth-boring tool of Embodiment 8, wherein the sidewall of the pocket comprises a first portion having a first diameter extending into the body a first depth along a central axis of the pocket and a second portion having a second diameter extending into the body a second depth along the central axis of the pocket, wherein the first diameter is greater than the second diameter and the second depth is greater than the first depth.
The earth-boring tool of any one of Embodiments 1 through 7, wherein the feature comprises a portion of the side surface of the bearing element within a substantially annular recess.
The earth-boring tool of any one of Embodiments 1 through 10, wherein the earth-boring tool is a fixed-cutter rotary drill bit.
An earth-boring tool, comprising: a body comprising a threaded receptacle in a leading end thereof for accepting at least a portion of a bearing element assembly; and a bearing element assembly disposed within the threaded receptacle, the bearing element assembly comprising: a holder with a receptacle at a distal end thereof for receiving a bearing element and a threaded outer surface at a proximal end thereof for engagement with the threaded receptacle in the body of the earth-boring tool; and at least one feature proximate the distal end of the holder configured to interface with a tool adapted to apply torque to the holder.
The earth-boring tool of Embodiment 12, wherein the threaded receptacle comprises a sleeve with an at least partially threaded inner diameter and a generally smooth outer diameter, and the sleeve is disposed within a pocket of the body.
The earth-boring tool of Embodiment 12 or Embodiment 13, further comprising a slot extending from an exterior surface of the body to a portion of an outer surface of the sleeve.
The earth-boring tool of any one of Embodiments 12 through 14, wherein the threaded outer surface of the holder is configured substantially identically to an outer surface of a nozzle insert for insertion in a fluid outlet port in the body of the earth-boring tool.
The earth-boring tool of Embodiment 15, wherein the bearing element assembly comprises an internal fluid passageway in communication with a fluid port in the body of the earth-boring tool and in communication with one or more fluid outlets in a side surface of the bearing element.
A method of replacing a bearing element of an earth-boring tool, comprising: disengaging a mechanical retention device retaining a first bearing element within a pocket in a body of the earth-boring tool; removing the first bearing element from the pocket; placing a second bearing element in the pocket, wherein the second bearing element comprises at least one of a shape of a bearing surface and an exposure of a bearing surface different from the first bearing element; and engaging the mechanical retention device to retain the second bearing element within the pocket.
The method of Embodiment 17, wherein disengaging the mechanical retention device comprises rotating the bearing element relative to the pocket to disengage threads on an outer surface of the bearing element from threads in a sidewall of the pocket.
The method of Embodiment 17, wherein disengaging the mechanical retention device comprises removing a retaining element from a groove in a sidewall of the pocket.
The method of Embodiment 17, wherein disengaging the mechanical retention device comprises applying a force to a surface of the bearing element with a tool inserted in a removal access hole extending through an exterior surface of the body and intersecting the pocket.
Although the foregoing description contains many specifics, these are not to be construed as limiting the scope of the present invention, but merely as providing certain exemplary embodiments. Similarly, other embodiments of the invention may be devised, which do not depart from the spirit or scope of the present disclosure. For example, features described herein with reference to one embodiment also may be provided in others of the embodiments described herein. The scope of the invention is, therefore, indicated and limited only by the appended claims and their legal equivalents, rather than by the foregoing description. All additions, deletions, and modifications to the disclosed embodiments, which fall within the meaning and scope of the claims, are encompassed by the present disclosure.