Drill bit cutter pocket restitution

BACKGROUND OF THE INVENTION

In downhole drilling applications, a cutting element may be implanted in a pocket on a surface of a degradation assembly. The cutting element may be held in the pocket by means of a press fit, braze, a thermal expansion process, mechanical means, or other means known in the art.

U.S. Pat. No. 4,109,737 to Bovenkerk which is herein incorporated by reference for all that it contains, discloses a pin longitudinally tapered at an angle chosen such that when mounted in recesses of a drill crown, a self-holding or self-locking friction fit is formed.

U.S. Pat. No. 4,199,035 to Thompson which is herein incorporated by reference for all that it contains, discloses a drill bit comprised of composite compact cutters removably secured or attached to a drill crown. The cutter is preferably comprised of a stud or pin with an abrasive composite compact bonded at one end of the stud. The securing means for the cutter is comprised of a sleeve and a bushing fixed in the recess of the bit crown. The sleeve has a threaded outer wall for engagement with a threaded inner wall of the bushing.

U.S. Pat. No. 6,772,849 to Oldham, et al., which is herein incorporated by reference for all it contains, discloses a method of increasing a durability of a drill bit having a bit body with at least one blade disposed thereon, at least one cutter pocket disposed on the blade, and at least one cutter disposed in the cutter pocket. The method includes brazing the at least one cutter to the at least one cutter pocket so that a braze material disposed between the at least one cutter pocket and the at least one cutter comprises an exposed surface, and overlaying at least a portion of the exposed surface with a hardfacing material, wherein the hardfacing material includes a binder having a melting point selected to avoid damaging the cutter.

U.S. Pat. No. 3,771,612 to Adcock which is herein incorporated by reference for all that it contains, discloses a replaceable wear-resistant element assembly having a wear-resistant element and a mounting device for releasably securing the element in the recess of a supporting body. The mounting device is constructed of a one-piece goblet shaped unit having a sleeve portion for receiving the element therein and a stem portion for supporting the element. The stem and sleeve portions are interconnected by a shearable web portion which will fracture when an axial force of sufficient magnitude is applied to the sleeve to cause the sleeve to move downward about the stem to release the element.

Regardless of how the cutting element is mounted within the pocket, frequently after use the pocket holding the cutting element may become worn and may need to be restored.

BRIEF SUMMARY OF THE INVENTION

A pocket restitution assembly comprises a pocket formed in a surface that includes a central axis, an anchor seated in the pocket and aligned with the central axis, a tool attachment comprising a cylindrical shaft and an end for connection to the anchor, and a hollow bit slidably and rotatably sitting on the tool attachment. The hollow bit may fit within the pocket.

The surface that includes the central axis may be disposed on a working face of a drill bit similar to those used in downhole drilling applications.

The cylindrical shaft forming part of the tool attachment may comprise an external threadform and the hollow bit may comprise an internal threadform, wherein the external threadform is designed to mate with the internal threadform. The cylindrical shaft may also comprise a substantially smooth outer diameter intermediate, or between, the external threadform and the end of the tool attachment. The end of the tool attachment may comprise a threaded connection to the anchor. The cylindrical shaft of the tool attachment may comprise a stopping rim disposed adjacent the end and extending a distance into the pocket when the end of the tool attachment is connected to the anchor. This connection may comprise threading the end of the tool attachment into the anchor. The hollow bit may then be slid along the cylindrical shaft of the tool attachment until it halts against the stopping rim. The pocket may then be shaped around an external surface of the hollow bit.

The hollow bit may comprise a top end formed to connect with a driver, wherein the driver may rotate the hollow bit around the cylindrical shaft of the tool attachment. The driver may be a hollow tube comprising an internal geometry formed to accept the top end of the hollow bit. The driver may alternately comprise an external geometry and the top end of the hollow bit may comprise an internal geometry, wherein the external geometry substantially mates with the internal geometry. The driver may be rotated by a hand drill, CNC machine, drill press or combinations thereof.

The hollow bit may additionally comprise an internal recess extending a length substantially equal to the distance of the stopping rim of the tool attachment, wherein the stopping rim may halt the linear advancement of the hollow bit when it makes contact with the internal recess.

The hollow bit may comprise an external geometry substantially the same shape as a cutting element, wherein as a weld material is introduced into the pocket it takes the shape of the external geometry. The hollow bit may comprise a roughing router that includes a cutting surface having at least one cutting blade, wherein as the roughing router rotates the cutting surface cuts a shape within the pocket substantially similar to a cutting element. Alternatively, the hollow bit may comprise a finishing router that includes a finishing surface having an abrasive material, wherein as the finishing router rotates the finishing surface cleans a shape within the pocket substantially similar to a cutting element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a perspective diagram of an embodiment of a rotary drag bit comprising cutting elements implanted in a surface.

FIG. 1b is a cross-sectional diagram of the embodiment of the rotary drag bit in FIG. 1a and a close-up view of a cutting element mounted in a pocket in a surface.

FIG. 2 is a cross-sectional diagram of an embodiment of a cutting element mounted in a pocket in a surface in the act of cutting an earthen formation.

FIG. 3a is a cross-sectional diagram of an embodiment of an anchor within the pocket in the surface of FIG. 2 after the cutting element has been removed and a tool attachment being inserted into the pocket.

FIG. 3b is a cross-sectional diagram of the embodiment of a tool attachment in FIG. 3a now secured to the anchor within the pocket in the surface.

FIG. 4a is a cross-sectional diagram of an embodiment of a hollow bit on the tool attachment within the pocket in the surface of FIG. 3b and a weld material being inserted into the pocket and substantially surrounding the hollow bit.

FIG. 4b is a cross-sectional diagram of the embodiment of a hollow bit on the tool attachment within the pocket in the surface of FIG. 4a and the weld material deposited within the pocket forming an interior of the pocket.

FIG. 5a is a perspective diagram of an embodiment of a hollow bit engaging with a driver.

FIG. 5b is a cross-sectional diagram of an embodiment of the hollow bit on the tool attachment of FIG. 4b being driven by a driver.

FIG. 6 is a cross-sectional diagram of an embodiment of a cutting element being inserted into the pocket of FIG. 5b with the interior formed of the weld material and after the hollow bit has been removed.

FIG. 7a is a perspective diagram of an embodiment of a hollow bit and a driver.

FIG. 7b is a perspective diagram of another embodiment of a hollow bit and a driver.

FIG. 8 is a cross-sectional diagram of an embodiment of a cutting element incorporated into a percussion drill bit.

FIG. 9 is a cross-sectional diagram and a close-up view of an embodiment of a cutting element incorporated into a roller cone bit.

FIG. 10 is a cross-sectional diagram of an embodiment of a cutting element incorporated into a pick.

FIG. 11 is a flow diagram of an embodiment of a method for restoring a pocket.

DETAILED DESCRIPTION OF THE INVENTION AND THE PREFERRED EMBODIMENT

Referring now to the figures, FIG. 1a displays a perspective diagram of an embodiment of a degradation assembly 150 comprising cutting elements 101a implanted in a surface 100a. In the embodiment shown the degradation assembly 150 is in the form of a rotary drag bit 160, however, the degradation assembly may also comprise a percussion drill bit, roller cone bit, a pick, or other degradation assemblies known in the art.

FIG. 1b displays a cross-sectional diagram of the embodiment of the rotary drag bit 160. The rotary drag bit 160 may comprise at least one blade 180 disposed on a working face 185. The blade 180 may comprise the surface 100a where at least one cutting element 101a may be inserted.

FIG. 2 displays a cross-sectional diagram of an embodiment of a cutting element 101b mounted in a pocket 102 within a surface 100b. The cutting element 101b may be brought into contact with a formation 230 in an attempt to degrade the formation 230. The formation 230 may be an earthen formation or types of manmade formations. After protracted exposure to the formation 230 the cutting element 101b may begin to dislodge from the pocket 102 and thus cause damage to the pocket 102. Following such wear it may be desirous to replace the cutting element 101b in an attempt to restore it to its original operating efficiency. Replacing the cutting element 101b may require repairing the pocket 102 and the surface 100b before a replacement cutting element 101b may be inserted.

Repairing the pocket 102 and surface 100b may involve first removing the cutting element 101b from the pocket 102. In cases of severe wear the cutting element 101b may have already dislodged from the pocket 102. After having removed the cutting element 101b from the pocket 102, the pocket 102 and surrounding surface 100b may be reformed.

FIGS. 3a and 3b display an anchor 201 disposed within the pocket 102 and along a central axis 202 of the pocket 102. A filler (such as filler 203 in FIG. 6 discussed below) may have been previously inserted into the anchor 201 to prevent loose material or debris from entering into the anchor 201, but already may have been removed using a common screwdriver or similar pointed object.

With the filler removed from the anchor 201, a tool attachment 200 may be secured into the anchor 201 through an end 205, such as a threadform or threaded connection, snap ring, press fit, adhesive, weld, latch, lock or combinations thereof. The tool attachment 200 may comprise a non-wettable surface that is non-wettable with weld material. FIG. 3a displays an embodiment of a tool attachment 200 being brought into the pocket 102. FIG. 3b displays an embodiment of the tool attachment 200 being secured into the anchor 201 via an end 205 having a threadform or threaded connection.

FIGS. 4a and 4b show a hollow bit 300a slidably and rotatably sitting on the tool attachment 200. The tool attachment 200 may provide for the hollow bit 300 to be centered within the pocket 102 and held in place.

The hollow bit 300a may comprise a block 320. The block 320 may comprise a material that is non-wettable with weld material 302. The block 320 may have this non-wettable material on an exterior surface or comprise a solid mass of non-wettable material. The non-wettable material may comprise graphite, pyrophyllite, certain ceramics, or combinations thereof.

The tool attachment 200 may comprise a stopping rim 301 and the hollow bit 300a may comprise an internal recess 311 such that the hollow bit 300a may slide along the tool attachment 200 until it reaches the stopping rim 301. The stopping rim 301 may place the hollow bit 300a substantially in the center of the pocket 102 and countersunk under the surface 100 to a specified depth.

With the hollow bit 300 in the pocket 102, weld 302 may be inserted intermediate or between the pocket 102 and the block 320. The weld 302 may be inserted by a welder 340. In the embodiment shown in FIG. 4a the welder 340 is in the form of a MIG welder, however, the welder 340 may also comprise a TIG, stick, or other type of welder known in the art. As shown in FIG. 4b, the weld 302 may conform to the shape of the block 320 such that a replacement cutting element may be fit within the restored pocket 102.

FIG. 5a displays an embodiment of a hollow bit 300a comprising a roughing router 420a. The roughing router 420a may comprise a cutting surface 405a comprising at least one cutting blade 410a. The hollow bit 300a may also comprise a top end 555a formed to mate with a driver 400a. The mating between the hollow bit 300a and the driver 400a may allow the driver 400a to rotate the hollow bit 300a. In some embodiments, the driver 400a may comprise a component 415a that may be a hand drill, CNC machine, drill press or combinations thereof.

FIG. 5b shows the roughing router 420a placed over the tool attachment 200 and being rotated by a driver 400a. The driver 400a may rotate the roughing router 420a causing the cutting surface 405a to cut a shape within the pocket 102 substantially similar to a cutting element.

In some embodiments, an internal threadform 430 on the roughing router 420a may interact with an external threadform 435 on the tool attachment 200. The interaction between the internal threadform 430 and the external threadform 435 may drive the roughing router 420a toward the pocket 102 and rough the weld 302. As the roughing router 420a continues to rotate the threadforms 430 and 435 may disengage. After the threadforms 430 and 435 disengage, the roughing router 420a may freely rotate about the tool attachment 200, still roughing the weld 302, but not translating further into the pocket 102.

FIG. 6 shows the now restored pocket 102 in the surface 100b. Upon completing a finishing operation on the weld 302, the hollow bits and tool attachment may be removed from the pocket 102. The anchor 201 may again be filled with a filler 203 to keep braze, loose material or other debris from entering the anchor 201. The filler 203 may comprise graphite. The filler 203 may be packed into the cavity of the anchor 201 but may also be easily removed when necessary. A replacement cutting element 101c may then be inserted into the restored pocket 102.

FIGS. 7a and 7b depict various embodiments of hollow bits 300b and 300c and drivers 400b and 400c, respectively. The hollow bit 300b may comprise a top end 555b formed to mate with the driver 400b in the embodiment shown in FIG. 7a. The top end 555b of the hollow bit 300b comprises an internal geometry 556 and the driver 400b comprises an external geometry 545, wherein the internal geometry 556 substantially mates with the external geometry 545. The internal geometry 556 may comprise the shape of a slot, cross, square, hexagon, or other geometry.

The hollow bit 300b may also comprise a finishing router 720 as shown in FIG. 7a. The finishing router 720 may comprise an abrasive surface 705. The abrasive surface 705 may comprise an abrasive material such as sandpaper, diamond grit, or other abrasive materials known in the art. The finishing router 720 may also comprise a solid abrasive form such as a grinding stone.

FIG. 7b shows an embodiment wherein the top end 555c of the hollow bit 300c comprises an external geometry 557 and the driver 400c comprises an internal geometry 546, wherein the external geometry 557 substantially mates with the internal geometry 546. The driver 400c in this embodiment may comprise a hollow tube. The internal geometry 546 may comprise the shape of a square, hexagon, octagon, star, or other geometry.

The embodiment of the hollow bit 300c as shown in FIG. 7b comprises a roughing router 420b. As mentioned previously, a roughing router 420b may comprise a cutting surface 405b comprising at least one cutting blade 410b.

Referring now to FIGS. 8 through 11, the cutting element may be inserted into pockets in various applications and the present invention may be used to restore those pockets. FIG. 8 shows an embodiment of a cutting element 101d incorporated into a percussion drill bit 800. The percussion drill bit 800 may comprise a surface 100c that includes at least one cutting element 101d that may be thrust into an earthen formation.

FIG. 9 shows an embodiment of a roller cone bit 1000. The roller cone bit 1000 may comprise at least one roller 1005. The roller 1005 may rotate while being forced into an earthen formation and thus wearing away at the formation. The roller 1005 may comprise a surface 100d comprising at least one cutting element 101e.

FIG. 10 shows an embodiment of a pick 1100. The pick 1100 may comprise a shank 1105 secured in a holder 1110. The holder 1110 may further be held in a block 1115 attached to a driving mechanism (not shown) that may thrust the pick into an earthen or manmade formation to degrade that formation. The shank 1105 may comprise a surface 100e on its distal end comprising a pocket 1102 and a cutting element 101f disposed within the pocket 1102.

FIG. 11 shows a flow diagram of an embodiment of a method 1200 for restoring a pocket. The method 1200 comprises the steps of providing a pocket formed in a surface and an anchor seated in the pocket 1201; connecting an end of a tool attachment comprising a cylindrical shaft to the anchor 1202; sliding a hollow bit along the cylindrical shaft of the tool attachment 1203; and shaping the pocket around an external surface of the hollow bit 1204.

Whereas the present invention has been described in particular relation to the drawings attached hereto, it should be understood that other and further modifications apart from those shown or suggested herein, may be made within the scope and spirit of the present invention.