DRILLING TOOL FOR ROTARY DRILLING Russian patent published in 1994 - IPC

FIELD: drilling tools for rotary drilling of holes and blast holes. SUBSTANCE: drilling tool has retainer in form of collar spring. Wings 3 are attached for limited rotation about their axes and interaction with one another in extreme positions. Distance from plane of contact to axis of rotation of each wing is less than distance from wing rotation axis to tool axis. Cutting member 5 is spaced at distance exceeding the distance of any point on surface of narrow faces of wing 3 to wing rotation axis. Wing 3 is asymmetric. EFFECT: higher efficiency. 2 cl, 6 dwg