DRILL BIT Russian patent published in 1998 - IPC

FIELD: mining industry; drilling machinery and equipment. SUBSTANCE: drill bit has body with nipple and blowout passages, valve units installed in blowout passages. Valve units are made up of shut-off member and return spring. Located in blowout passage of valve unit is cellular bottom-screen. Shut-off member and return spring together with cellular bottom-screen are arranged inside drill bit body for unobstructed flowing of blowout agent between inner surface of hole in body and shut-off member for protection against influence of sludge particles. Cellular bottom-screen is secured at hole outlet in body by stop so as to ensure easy and quick replacement of valve unit with another one having required bore area of cellular bottom-screen. EFFECT: higher efficiency. 4 cl, 13 dwg