CIRCULAR DRILL BIT Russian patent published in 1997 - IPC

FIELD: hole drilling. SUBSTANCE: circular drill bit is designed for prospecting drilling to evaluate underground reservoirs. It has body mounted for rotation relative to certain rotation axis, plates provided on body on its front part, collection of cutters arranged along each plate and each having cutting edge. Assemblage of these cutting edges forms imaginary envelope located around drilled out core and nozzles which feed jet of washing fluid into face and which have outlet in front pert of body. At least one nozzle has outlet deflecting jet of washing fluid obliquely forward with regard to rotation axis away from drilled out core, predominantly at angle more than 45 def or 50 deg. EFFECT: increased drilling efficiency. 21 cl, 5 dwg