Raise drilling bit with detachable stem
AssigneeReed Tool Company
InventorsByron W. Chitwood, Thomas E. Winship
Life of this patent
Estimating the term…
Abstract
A rotary drill bit for producing a raise bore about a pilot hole comprises a drill head having an upper surface for mounting cutter assemblies and lower surface spaced from said upper surface. The upper and lower surfaces are secured to and connected by a body sub. A drive stem is removably secured in the drive sub. The drive sub and stem have mating tapered portions for a press fit. Either the sub or the stem is provided with a spiral groove through which oil is injected under high pressure to expand the sub while the stem is rammed into place under high pressure. The stem can be removed by application of oil pressure and a ram force in the opposite direction.
Claims3
A rotary raise drill bit for producing a raise bore by disintegrating the earth formation surrounding a pilot hole comprising:
- a drill heat having an upper mounting member,
- a plurality of cutters secured to said upper mounting member,
- a drill stem,
- a supporting sub secured to said upper mounting member and having a vertical passage tapered outward toward its lower end portion for receiving said drill stem,
- said drill stem having an upper portion smaller in size than the passage in said sub and operable to pass therethrough during assembly and a lower portion larger in size than said passage prior to assembly and tapered to fit said passage when expanded,
- the outer tapered surface of the lower portion of said drill stem and the lower tapered surface of said passage being of a shape to mate with a longitudinally sliding fit during assembly, and
- means extending through the wall of said sub to apply force into said passage to expand the same during longitudinal sliding assembly to provide a compression fit of said passage on said lower portion of said drill stem after relaxation of said force, and the difference in size and the taper of said passage in said sub and said drill stem lower portion being such that said compression fit is in excess of the maximum torque encountered in drilling.
Dependencies are inferred from the claim text.