DRILLING TOOL Russian patent published in 1994 - IPC

FIELD: well drilling equipment. SUBSTANCE: drilling tool secured to drill pipe consists of multicone drill bit, branch pipe with auger spiral rigidly attached to it. Branch pipe is fitted on pipe string with ports coinciding with those of branch pipe. Drilling tool includes also two rigidly connected removable drilling knives with cutting edges installed square to pipe axial line. Freely moved inside pipe string on rope is skip for transportation of drilled rock. Knife cutting edges may be installed at acute angle, and drilling knives may be replaced with pipe with drilling scrapers and ports. Pipe is secured in stops for rotation by means of gear systems located between branch pipe and pipe string. EFFECT: higher efficiency. 2 cl, 5 dwg