| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill body, the peripheral and negatively angled part edges of which are strong to enable the best service life of the drill body.SOLUTION: A drill body has a front head (4) which is provided with two cutting edges and is formed at the front end. A first part edge is included in a central tip part (8) having a front chisel edge (29), and a second part edge extends between a peripheral end point (11) and a radially-inner end point (12) where the second part edge transforms into the first part edge (9). Two part surfaces (13a, 13b) of a primary clearance surface (13) meet each other in a chute bottom (17). The drill body is provided with a second chute bottom (30), and the second chute bottom (30) extends in an extension of the first chute bottom (17) and separates two second part surfaces (15a, 15b) included in a secondary clearance surface (15). |
