| 摘要 |
Disclosed is a drilling tool comprising a first drill bit ( 2 ) that is provided with at least two forward cutting edges ( 4, 5 ) and a second drill bit ( 3 ) which encompasses at least two rear cutting edges ( 6, 7 ). A cutting groove ( 8, 9 ) runs continuously from one respective forward cutting edge ( 4, 5 ) to a rear cutting edge ( 6, 7 ). Said cutting groove ( 8, 9 ) is embodied in an asymmetric manner in an area (A) bordering the forward drill bit ( 2 ), in a symmetric manner in a central area (B), and asymmetric in an area (C) bordering the rear drill bit ( 3 ).
|
