DRILLING DEVICE Russian patent published in 1999 - IPC

FIELD: drilling machinery and equipment. SUBSTANCE: this can be used for drilling bore-holes in unstable ground. Drilling device has casing pipe with internal protrusion in its forward part, bottom-hole percussive machine with case-drilling tool which is made up of anvil interacting with casing pipe and rock-crushing bit secured by its tail part in anvil. Rock-crushing bit is provided with pilot stage and widening stage. Rock-crushing bit is positioned eccentrically relative to axis of anvil. Pilot stage is made eccentric with respect to axis of tail part of rock-crushing bit. In addition, rock-crushing bit is installed in anvil with eccentricity and is secured for possible axial displacement by means of leading bush provided with end-face cam, and by two half-rings. Aforesaid embodiment of drilling device improves reliability and efficiency of operation. EFFECT: higher efficiency. 5 dwg