Detachable shoe plates for large diameter drill bits
OwnerAllen E. Bardwellinventor
Life of this patent
Estimating the term…
Abstract
Shoe members and drill shank members for large diameter cable drilling bits are provided with a tongue on one of the members that projects axially relative to the drill shank member and with an arcuate lip and projecting stop on the other of the members to trap the tongue and prevent radial movement of the shoe member in response to radially directed forces caused by the spinning of the bit in drilling operations. Such forces would impose shear stresses on the fastening members that extend through the shoe member and axially into the drill shank. Four embodiments are disclosed: a spudding bit, two star bits and a scow bit.
Claims10
An improved drill bit for gravity-drop cable drilling, the bit comprising:
- an elongated shank member having a bottom diametrical portion;
- a shoe member with a metal shoe body and with inserts of a metal that is harder than the metal of the shoe body, some of the inserts projecting at an angle from a bottom of a toe on the shoe body, these angularly projecting inserts being operable to cut along an outer edge of a hole being drilled;
- fastener means extending through the shoe member and into the shank member in an axial direction relative to the shank member for removably coupling the shoe member in a fixed position along the bottom diametrical portion of the shank member;
- wherein one of the members coupled together by the fastener means has a tongue projecting axially relative to the shank member and disposed longitudinally relative to the bottom diametrical portion of the shank member;
- and
- wherein the other of the members coupled together by the fastener means has an arcuate lip that opposes a radially outward facing side of the tongue and also has a projecting stop that opposes a radially inward facing side of the tongue to cooperate with the lip in restraining radial movement of the shoe member along the bottom diametrical portion of the shank member in response to radial shear forces encountered during cable drilling operations.
Dependencies are inferred from the claim text.