| 摘要 |
FIELD: metal working; cutting of holes. ^ SUBSTANCE: proposed drill has front end with at least two cutting edges which forms drilled hole in blank, rear end and several flutes whose number corresponds to number of cutting edges, passing from front end in direction to rear end and designed to form and remove chips from corresponding cutting edges. Each cutting edge has main edge passing from its central end to peripheral end, central end being arranged along axis opposite to peripheral end, and secondary edge at peripheral end of main edge, said secondary edge being made curved. To increase speed of cutting and improved quality of machined surface, secondary edge is provided with front, intermediate and rear circular segments of different radii. Radius of front segment is smaller than radius of intermediate segment, but is greater than radius of rear segment. ^ EFFECT: increased cutting speed, improved quality of machined surface. ^ 4 cl, 10 dwg |
