Patent ID: 6397956
Filing Date: 2002-06-04
Classification: E21B

Abstract:
A rotary-percussion device for directional drilling in rock comprising:a frustoconical head; a neck portion integral with the head; and a substantially cylindrical, rotatable body having a tubular forwardmost part, the head being eccentrically mounted to a front of the body with the neck portion slidingly received in the tubular forwardmost part of the body, wherein the head includes a front face and a rear face, the rear face is adjacent to the forwardmost part of the body, no portion of the body extends forward of the rear face, the axis of the head is parallel to, but offset from the axis of the body, and the front face of the head is chisel-shape and includes at least one oblique plane sloping forwardly in the same direction as the offset of the head axis relative to the body axis.