Twist-drill bit

摘要

A helical drill bit (1) for rock has an axially extending shank (2) located between a chuck insert end (3) and an opposite drilling head (4) with at least one axially extending helical discharge groove (7) extending radially inwardly from the outer circumferential surface of the shank. A radially projecting groove reinforcement (9) is arranged in the base of the radial groove (8), with the reinforcement changing its geometric form or its position within the discharge groove (7) along the discharge groove (7).