CROWN BIT Russian patent published in 1994 - IPC

FIELD: rock cutting tool for well drilling. SUBSTANCE: relation between the sum of end face areas of core and well forming members and end face area of cutting member is within 0.5 to 0.8. Relation between height of cutting member and its width is within 0.501.0. End face of each sector between core and well forming members has recess. Recess bottom is made with radius equalling 1/3 of sector end face width. Recess depth equals half the radius. Height of core forming member exceeds that of well forming member by value determined by expression given in invention description. EFFECT: higher efficiency. 3 cl, 5 dwg