Fail-resistant hammer assembly for a valveless percussive drill
AssigneeJ.H. Fletcher & Co.
InventorWard D. Morrison
Life of this patent
Estimating the term…
Abstract
In a valveless percussive drill of the hydraulic type and incorporating a hammer assembly, an “intermediate” shoulder between the head portion and cushion portion of a reciprocating piston engages the end face of a distributor or liner, rather than an interior bearing structure for the piston. This end face can be made harder than the ulterior bearing structure, which may include a surface made of a different material than the piston. Collectively, the result is a percussive drill with the hammer assembly incorporating the piston substantially less susceptible to failure due to galling as the result of contamination in the working fluid.
Claims21
An apparatus for forming part of a valveless percussive drill for use with a working liquid, comprising:
- a piston adapted for reciprocating movement in a longitudinal direction, the piston having an oversized head portion, a stem portion, a cushion portion, and at least one shoulder positioned at least partially between the head portion and the cushion portion;
- and
- a tubular body for receiving the piston, the body having a cushion pocket for engaging the cushion portion, an interior surface resistant to galling due to the presence of any contaminant in the working liquid and a hardened end face for engaging the shoulder of the piston in the event of overtravel in the longitudinal direction.
A method of forming part of a valveless percussive drill for use with a working liquid, comprising:
- providing a piston with an oversized head portion, a stem portion, a cushion portion, and at least one shoulder at least partially between the head portion and the cushion portion;
- positioning the piston at least partially in a tubular body having a cushion pocket for engaging the cushion portion, an interior surface resistant to galling and a hardened end face for engaging the shoulder of the piston in the event of overtravel in a longitudinal direction.
A method of manufacturing a liner assembly for use in connection with a piston in a percussive drill, comprising:
- forming a tubular body of a first material for receiving the piston, the body having an interior surface and an end face;
- providing a lining formed of a second material resistant to galling along at least a portion of the interior surface;
- after the providing step, hardening at least the end face.
An apparatus for performing drilling, comprising:
- a valveless percussive drill including:
- (1) a piston adapted for reciprocating movement in a longitudinal direction, the piston having an oversized head portion, a stem portion, a cushion portion, and at least one shoulder positioned at least partially between the head portion and the cushion portion;
- and (2) a tubular body for receiving the piston, the body having a cushion pocket for engaging the cushion portion, an interior surface resistant to galling and a hardened end face for engaging the shoulder of the piston in the event of overtravel in the longitudinal direction.
Dependencies are inferred from the claim text.