The cutting teeth (3) are in contact with each other in the area of the bolt diameter (6). Gaps are formed between the cutting edges (9). The conical bolt (1) carries the impact sleeve (2) and the cutting teeth, which are held together by the spring ring (4). The lower edges (5) of the teeth are in contact with each other and locked. The sleeve transmits the impact force with its end face (7) to the end faces (8) of the teeth. The teeth have grooves (10), which angle the teeth during undercutting.
