DRILL FOR OIL WELLS PERFORATOR Russian patent published in 2004 - IPC

FIELD: mining industry. SUBSTANCE: device has a shaft with an element for connecting with drive, head with cutting members. Shaft is made bendable. Head is provided with benched cutting members in form of central or peripheral hard alloyed plates. Size of calibrating edges of central plate is no more than 0.6 of diameter of calibrating edge of peripheral plates. Point of intersection of calibrating and cutting edges of central plate is distant from cutting edges of peripheral plates for not less than 1.1 of casing string thickness. Inclination angle of cutting edges of peripheral plates is made along crookedness of casing string outer surface. Ends of bendable shaft are placed in cylindrical recesses in the end part of drive connection element and benched head, said recesses being of depth not less than 1.25 of bendable shaft diameter. EFFECT: lowered drive power costs for metal cutting, increased reliability and durability of cutting tools. 3 dwg