Directional drilling tool - where front face of head is chisel shaped and comprises at least one oblique plane sloping forward in same direction as the head axis offset relative to body axis

摘要

A substantially cylindrical, rotating body portion (15) houses a percussion hammer. A frustoconical head (2) is eccentrically mounted on front of body portion, where minimum diameter face (3) of head is adjacent the body portion, axis of head being parallel to, but offset from, axis of the body. The front face (4) of head is chisel-shaped and comprises at least one oblique plane (11) sloping forward in same direction as offset of head axis relative to body axis. - An independent claim is also included for: a backreaming tool comprising a drill rod, two or more percussion hammers around periphery of drill rod, with their axes parallel to drill rod axis, and air outlets on the heads of the hammers. The tool passes through a pilot bore in a direction opposite to the original drilling direction to widen the bore.