Drag bit excavation
AssigneeRapidex, Inc.
InventorsCarl R. Peterson, Allan T. Fisk
Life of this patent
Estimating the term…
Abstract
A drag bit excavating device comprising a core extending along an axis; a bit carrier supported on the core; cutter bits supported by the carrier along a three dimensional spiral having constant pitch and increasing radius along at least a portion of the axis, the carrier being relieved to provide radially extending spaces between the turns of the spiral; a frame supporting the core, carrier, and bits for rotation about and advance along the axis; and a drive to provide rotation, whereby the bits slot the material to be excavated while the material between portions of the resulting slot extends into the spaces to be subsequently broken away.
Claims36
A drag bit excavating device comprising
- a core extending along an axis,
- a bit carrier supported on said core,
- cutter bits supported by said carrier along a three dimensional spiral having a constant pitch P and increasing radius along at least a portion of said axis,
- said carrier being relieved to provide radially extending spaces between the turns of said spiral,
- a frame supporting said core, carrier, and bits for rotation about and advance along said axis,
- a drive to provide said rotation and said advance at the rate of one pitch P per revolution, and
- means including said bits for cutting in the material to be excavated a slot of depth that increases with said advance, while leaving between portions of said slot and extending into said spaces, to be subsequently broken away, the major portion of said material to be excavated.
A method of excavating comprising the steps of
- (a) providing a device comprising
- a core extending along an axis,
- a bit carrier supported on said core,
- cutter bits supported by said carrier along a three dimensional spiral having a constant pitch P and increasing radius along at least a portion of said axis, said carrier being relieved to provide radially extending spaces between the turns of said spiral,
- a frame supporting said core, carrier, and bits for rotation about and advance along said axis,
- a drive to provide said rotation and said advance at the rate of one pitch P per revolution, and
- means including said bits for cutting in the material to be excavated a slot of depth that increases with said advance, while leaving between portions of said slot and extending into said spaces, to be subsequently broken away, the major portion of said material to be excavated;
- (b) advancing said device along said axis while rotating said core, carrier, and bits about said axis;
- and
- (c) breaking away said material extending into said spaces after passage through said slot of a said bit at the maximum radius of said carrier.
Dependencies are inferred from the claim text.