Fixed cutter drill bits with mechanically attached cutter element assemblies

Abstract

A fixed cutter drill bit for drilling an earthen formation has a central axis and a cutting direction of rotation about the central axis. The drill bit includes a bit body configured to rotate about the central axis in the cutting direction of rotation. The bit body includes a bit face and a blade extending radially along the bit face. The blade has a leading side relative to the cutting direction of rotation, a trailing side relative to the cutting direction of rotation, and a cutter-supporting surface extending from the leading side to the trailing side. The blade includes a socket extending from the leading side of the blade and penetrating the cutter-supporting surface of the blade. The socket has a central axis, an open end at the leading side of the blade, and a closed end distal the leading side of the blade. The socket has (i) a first width W 1 in a front view of the blade measured parallel to a projection of the cutter-supporting surface across the socket in the front view at a first distance D 1 measured perpendicular to the projection of the cutter-supporting surface in the front view, and (ii) a second width W 2 in a front view of the blade measured parallel to the projection of the cutter-supporting surface across the socket in the front view at a second distance D 2 measured perpendicular to the projection of the cutter-supporting surface in the front view. The second distance D 2 is greater than the first distance D 1 and the second width W 2 at the second depth D 2 is greater than the first width W 1 at the first width W 1. In addition, the drill bit includes a cutter element assembly mounted to the blade and extending from the cutter-supporting surface of the blade. The cutter element assembly includes a cutter element carrier seated in the socket and fixably attached to the blade. The cutter element carrier includes a base that mates with the socket. The cutter element assembly also includes a cutter element fixably attached to the cutter element carrier.

What is claimed is: 
     
         1 . A fixed cutter drill bit for drilling an earthen formation, the drill bit having a central axis and a cutting direction of rotation about the central axis, the drill bit comprising:
 a bit body configured to rotate about the central axis in the cutting direction of rotation, wherein the bit body includes a bit face;   a blade extending radially along the bit face, wherein the blade has a leading side relative to the cutting direction of rotation, a trailing side relative to the cutting direction of rotation, and a cutter-supporting surface extending from the leading side to the trailing side, wherein the blade includes a socket extending from the leading side of the blade and penetrating the cutter-supporting surface of the blade;   wherein the socket has a central axis, an open end at the leading side of the blade, and a closed end distal the leading side of the blade;   wherein the socket has (i) a first width W 1  in a front view of the blade measured parallel to a projection of the cutter-supporting surface across the socket in the front view at a first distance D 1  measured perpendicular to the projection of the cutter-supporting surface in the front view, and (ii) a second width W 2  in a front view of the blade measured parallel to the projection of the cutter-supporting surface across the socket in the front view at a second distance D 2  measured perpendicular to the projection of the cutter-supporting surface in the front view, wherein the second distance D 2  is greater than the first distance D 1  and the second width W 2  at the second depth D 2  is greater than the first width W 1  at the first width W 1 ;   a cutter element assembly mounted to the blade and extending from the cutter-supporting surface of the blade, wherein the cutter element assembly comprises:
 a cutter element carrier seated in the socket and fixably attached to the blade, wherein the cutter element carrier includes a base having a central axis, a leading face proximal the leading side of the blade, and a trailing face distal the leading side of the blade, wherein the base mates with the socket; 
 a cutter element fixably attached to the cutter element carrier. 
   
     
     
         2 . The fixed cutter drill bit of  claim 1 , wherein the cutter element carrier further comprises a support block extending from the base, wherein the support block and the base define a pocket, wherein the cutter element is seated in the pocket. 
     
     
         3 . The fixed cutter drill bit of  claim 2 , wherein the cutter element comprises a substrate and a cutting layer bonded to the substrate, wherein the substrate has a central axis and the cutting layer defines a cutting face of the cutter element;
 wherein the cutter element has a leading end relative to the cutting direction of rotation, a trailing end relative to the cutting direction of rotation, and a radially outer surface extending axially relative to the central axis of the substrate from the leading end to the trailing end;   wherein the trailing end of the cutter element engages the support block, and wherein the radially outer surface of the cutter element engages and is fixably attached to the base.   
     
     
         4 . The fixed cutter drill bit of  claim 3 , wherein the cutter element includes a recess extending from the trailing end of the cutter element and the support block includes a projection extending into the recess of the cutter element. 
     
     
         5 . The fixed cutter drill bit of  claim 3 , wherein the support block includes a throughbore or a recess extending from a leading side of the support block and the cutter element includes a projection extending from the trailing end of the cutter element into the throughbore or the recess. 
     
     
         6 . The fixed cutter drill bit of  claim 2 , wherein the cutter element comprises a cutting layer defining a cutting face of the cutter element and a projection extending from the cutting layer;
 wherein the support block includes a throughbore extending from a leading side of the support block; and   wherein the projection of the cutter element is secured within the throughbore of the support block by an interference fit.   
     
     
         7 . The fixed cutter drill bit of  claim 6 , wherein the cutter element carrier includes a slit extending axially relative to the central axis of the base from the leading face of the base to the trailing face of the base and extending radially relative to the central axis of the base from the throughbore of the support block through the support block and the base. 
     
     
         8 . The fixed cutter drill bit of  claim 6 , wherein the cutting layer and the projection are monolithic and made of polycrystalline diamond or polycrystalline cubic boron nitride. 
     
     
         9 . The fixed cutter drill bit of  claim 3 , wherein the base has a concave cylindrical cutter element facing surface that engages and is fixably attached to the cutter element. 
     
     
         10 . The fixed cutter drill bit of  claim 2 , wherein the cutter element carrier includes an internally threaded throughbore extending through the support block and the base, wherein a set screw threadably engages the internally threaded throughbore and has a tip seated in a counterbore extending from the socket into the blade. 
     
     
         11 . The fixed cutter drill bit of  claim 2 , wherein the cutter element carrier includes a counterbore extending from the leading face of the base and a throughbore extending from the counterbore through the base to the trailing face of the base
 wherein a bolt is seated in the counterbore, extends through the throughbore, and is threaded into an internally threaded bore extending from the socket into the blade.   
     
     
         12 . The fixed cutter drill bit of  claim 1 , further comprising:
 a counterbore extending from the socket into the blade;   a biasing member seated in the counterbore;   a pin partially disposed in the counterbore and biased into the socket by the biasing member, wherein the pin has an end seated in a recess of the base of the cutter element carrier.   
     
     
         13 . The fixed cutter drill bit of  claim 1 , wherein the base has a concave cylindrical cutter element facing surface that engages and is fixably attached to the cutter element;
 wherein the cutter element carrier further comprises a pair of lateral sidewalls extending circumferentially from the base, wherein each lateral sidewall has a radially inner concave cylindrical surface that engages and is fixably attached to the cutter element.   
     
     
         14 . The fixed cutter drill bit of  claim 1 , wherein the socket has a dovetail shape in the front view of the blade and the base has a mating dovetail shape in the front view of the blade. 
     
     
         15 . The fixed cutter drill bit of  claim 2 , wherein a trailing end of the cutter element comprises a planar surface that is flush with a planar surface of the support block;
 wherein the base includes a concave cylindrical cutter element facing surface that engages and is fixably attached to the cutter element;   wherein the base includes an indexing surface extending from the concave cylindrical cutter element facing surface to the planar surface of the support block, wherein the indexing surface engages a mating indexing surface of the cutter element to rotationally position the cutter element relative to the cutter element carrier.   
     
     
         16 . A fixed cutter drill bit for drilling an earthen formation, the drill bit having a central axis and a cutting direction of rotation about the central axis, the drill bit comprising:
 a bit body configured to rotate about the central axis in the cutting direction of rotation, wherein the bit body includes a bit face;   a blade extending radially along the bit face, wherein the blade has a leading side relative to the cutting direction of rotation, a trailing side relative to the cutting direction of rotation, and a cutter-supporting surface extending from the leading side to the trailing side, wherein the blade includes a socket extending from the leading side of the blade and penetrating the cutter-supporting surface of the blade;   wherein the socket has a central axis, an open end at the leading side of the blade, and a closed end distal the leading side of the blade;   wherein the socket is defined by a base surface of the blade extending axially relative to the central axis of the socket from the leading side of the blade, a first lateral side surface extending axially relative to the central axis of the socket from the leading side of the blade, and a second lateral side surface extending axially relative to the central axis of the socket from the leading side of the blade, wherein the base surface of the blade is distal the cutter-supporting surface, wherein the first lateral side surface and the second lateral side surface are disposed on opposite lateral sides of the central axis of the socket, and wherein each lateral side surface extends from the cutter-supporting surface to the base surface of the blade;   wherein the first lateral side surface of the blade includes at least a portion that slopes or curves away from at least a portion of the second lateral side surface of the blade moving away from the cutter-supporting surface to toward the base surface of the blade in a front view of the blade;   a cutter element assembly removably mounted to the blade and extending from the cutter-supporting surface of the blade, wherein the cutter element assembly comprises:
 a cutter element carrier seated in the socket and fixably attached to the blade, wherein the cutter element carrier includes a base having a central axis, a leading end proximal the leading side of the blade, and a trailing end distal the leading side of the blade; 
 wherein the base of the cutter element carrier mates with the socket and has an outer surface comprising a cutter element facing surface extending axially relative to the central axis of the base from the leading end of the base to the trailing end of the base, a first lateral side surface extending axially relative to the central axis of the base from the leading end of the base to the trailing end of the base, and a second lateral side surface extending axially relative to the central axis of the base from the leading end of the base to the trailing end of the base; 
 wherein the blade facing surface of the base slidingly engages the base surface of the blade, the first lateral side surface of the base engages the first lateral side surface of the blade, and the second lateral side surface of the base engages the second lateral side surface of the blade; and 
 a cutter element fixably attached to the cutter element carrier. 
   
     
     
         17 . The fixed cutter drill bit of  claim 16 , wherein the base surface of the blade includes a planar surface and the blade facing surface of the base of the cutter element carrier includes a planar surface that is flush with and engages the planar surface of the base surface of the blade. 
     
     
         18 . The fixed cutter drill bit of  claim 16 , wherein the cutter element carrier further comprises a support block extending from the base, wherein the support block and the base define a pocket, and wherein the cutter element is seated in the pocket. 
     
     
         19 . The fixed cutter drill bit of  claim 18 , wherein the cutter element includes a recess extending from a trailing end of the cutter element and the support block includes a projection extending into the recess of the cutter element. 
     
     
         20 . The fixed cutter drill bit of  claim 18 , wherein the support block includes a throughbore extending from a leading face of the support block and the cutter element includes a projection extending from a trailing end of the cutter element into the throughbore. 
     
     
         21 . The fixed cutter drill bit of  claim 20 , wherein the projection of the cutter element is secured in the recess or the throughbore by an interference fit. 
     
     
         22 . The fixed cutter drill bit of  claim 16 , wherein the base has a concave cylindrical cutter element facing surface that engages and is fixably attached to the cutter element. 
     
     
         23 . The fixed cutter drill bit of  claim 16 , wherein the cutter element carrier includes an internally threaded throughbore extending through the support block and the base, wherein a set screw threadably engages the internally threaded throughbore and has a tip seated in a counterbore extending from the base surface of the blade. 
     
     
         24 . The fixed cutter drill bit of  claim 16 , wherein the cutter element carrier includes a counterbore extending from the leading face of the base and a throughbore extending from the counterbore through the base to the trailing face of the base;
 wherein a bolt is seated in the counterbore, extends through the throughbore, and is threaded into an internally threaded bore extending from the socket into the blade.   
     
     
         25 . The fixed cutter drill bit of  claim 16 , wherein the first lateral sidewall of the socket includes a planar surface oriented at an angle a relative to a reference plane oriented perpendicular to a projection of the cutter-supporting surface across the socket in a front view of the blade, wherein the second lateral sidewall of the socket includes a planar surface oriented at an angle a relative to the reference plane in the front view, wherein each angle a is a negative draft angle ranging from 25° to 75°.