Rotational drill bits and apparatuses including the same
View Patent ↗A subterranean support-bolt drill bit has a bit body rotatable about a central axis, the bit body having a forward end and a rearward end axially spaced away from the forward end. The support-bolt drill bit includes at least one bit cutting element coupled to the bit body, the at least one bit cutting element including a cutting edge. The support-bolt drill bit also includes a central pilot projecting from the bit body beyond the at least one bit cutting element in an axially forward direction, the central pilot including a pilot cutting edge.
1. A subterranean support-bolt drill bit, comprising:
a bit body rotatable about a central axis, the bit body having a forward end and a rearward end axially spaced away from the forward end;
at least one bit cutting element coupled to the bit body, the at least one bit cutting element comprising a cutting edge; and
a central pilot projecting from the bit body beyond the at least one bit cutting element in an axially forward direction, the central pilot comprising a plurality of pilot cutting elements mounted in cutter pockets defined in a forward end of the central pilot, wherein the plurality of pilot cutting elements are spaced from the bit body by a substantially cylindrical peripheral surface of the central pilot that extends axially between the bit body and the cutter pockets.
2. The subterranean support-bolt drill bit of claim 1 , wherein each of the plurality of pilot cutting elements comprises a cutting edge.
3. The subterranean support-bolt drill bit of claim 2 , wherein each of the plurality of pilot cutting elements is axially spaced away from the forward end of the bit body.
4. The subterranean support-bolt drill bit of claim 2 , wherein the plurality of pilot cutting elements are spaced substantially equally about the central axis.
5. The subterranean support-bolt drill bit of claim 2 , wherein each of the plurality of pilot cutting elements comprises a cutting face having a substantially semi-circular periphery.
6. The subterranean support-bolt drill bit of claim 2 , wherein the plurality of pilot cutting elements form a generally apical cutting tip centered about the central axis.
7. The subterranean support-bolt drill bit of claim 1 , wherein the central pilot is integrally formed with the bit body.
8. The subterranean support-bolt drill bit of claim 1 , wherein the central pilot is secured within a recess extending through at least a portion of the bit body.
9. The subterranean support-bolt drill bit of claim 1 , wherein at least a portion of at least one of the plurality of pilot cutting elements and the at least one bit cutting element comprises a superabrasive material.
10. The subterranean support-bolt drill bit of claim 9 , wherein the superabrasive material comprises polycrystalline diamond.
11. The subterranean support-bolt drill bit of claim 1 , wherein the at least one bit cutting element comprises a plurality of bit cutting elements.
12. The subterranean support-bolt drill bit of claim 11 , wherein the plurality of bit cutting elements comprises two bit cutting elements or three bit cutting elements.
13. The subterranean support-bolt drill bit of claim 1 , further comprising a coupling shank extending generally parallel to the central axis.
14. The subterranean support-bolt drill bit of claim 13 , wherein the central pilot is connected to the coupling shank by a connection member extending through a hole defined in the bit body.
15. The subterranean support-bolt drill bit of claim 1 , wherein the cutting edge of the at least one bit cutting element extends radially beyond the central pilot relative to the central axis.
16. The subterranean support-bolt drill bit of claim 1 , wherein the central pilot has a length of approximately 0.5 inches or more in the axial direction.
17. A subterranean support-bolt drilling assembly, comprising:
a drill steel; and
a drill bit mounted to the drill steel, the drill bit comprising:
a bit body rotatable about a central axis, the bit body having a rearward end adjacent the drill steel and a forward end axially spaced away from the rearward end;
at least one bit cutting element coupled to the bit body, the at least one bit cutting element comprising a cutting edge; and
a central pilot projecting from the bit body beyond the at least one bit cutting element in an axially forward direction, the central pilot comprising a plurality of pilot cutting elements mounted in cutter pockets defined in a forward end of the central pilot, wherein the plurality of pilot cutting elements are spaced from the bit body by a substantially cylindrical peripheral surface of the central pilot that extends axially between the bit body and the cutter pockets.
18. The subterranean support-bolt drilling assembly of claim 17 , wherein each of the plurality of pilot cutting elements comprises a cutting edge.
19. The subterranean support-bolt drilling assembly of claim 17 , wherein the drill bit further comprises a coupling shank extending into a portion of the drill steel.