Under-reaming pile bore excavator
OwnerHachiro Inoueinventor
Life of this patent
Estimating the term…
Abstract
An under-reaming pile bore excavator by which a straight pile bore is first excavated vertically to a given depth by rotating the main drill bits and the under-reamed bore is next excavated downward and outward into a given shape by rotating the slidable wing bits. The under-reaming pile bore excavator of the present invention comprises a plurality of guide rails, and a plurality of slidable wing bits mounted on the guide rails which excavate the under-reamed bore, in addition to the conventional main drill bits which excavate the straight pile bore. In using the under-reaming pile bore excavator of the present invention, it is possible to obtain a stable impermeable soil surface on the excavated bore to prevent water from penetrating into the soil wall and to prevent lumps of soil from being dislodged therefrom.
Claims6
An under-reaming pile bore excavator which comprises:
- (a) an inner pipe to which an excavating torque is applied;
- (b) an outer pipe telescopically connected to said inner pipe, said outer pipe being rotated together with said inner pipe in either direction;
- (c) a plurality of main drill bits fixed to the bottom of said outer pipe at an appropriate bit angle to excavate a straight pile bore;
- (d) a plurality of guide rails fixed to said outer pipe at an inclined angle with respect to the axis of said outer pipe;
- and
- (e) a plurality of slidable wing bits slidably mounted onto said guide rails at an appropriate bit angle to excavate an under-reamed pile bore when moved downward and outward along said guide rails, said slidable wing bits being movably connected to said inner pipe so as to extend in the radial direction along said guide rails,
- whereby a straight pile bore is first excavated by said main drill bits with said slidable wing bits fixed in their uppermost position and then the under-reamed pile bore is excavated by moving said slidable wing bits downward and thus extending them outward along said guide rails by the force of gravity applied thereto.
Dependencies are inferred from the claim text.