| 摘要 |
The screw has an elongate tubular shaft provided with an external thread. A bit (3) is arranged with teeth (4), where the bit is provided at a longitudinal end of the shaft. Each tooth is arranged with cutting edges (5, 10). A notch (8) is formed in the bit at a base (5a) of each cutting edge for delimiting a sharpening reserve of an associated tooth. An indicator is arranged in the notch for defining an end-of-life status of the bit. |
