DIRECTIONAL DRILLING TOOL

摘要

A rotary-percussion device for directional drilling in rock comprises a substantially cylindrical, rotatable body portion (15) housing a percussion hammer, and a frustroconical head (2) eccentrically mounted on the front of the body portion. The minimum diameter face (3) of the head is adjacent to the body portion. The axis (6) of the head is parallel to but offset from the axis (5) of the body. The front face (4) of the head is chisel-shaped and comprises at least one oblique plane (11) sloping forwardly in the same direction as the offset of the head axis relative to the body axis.