| 摘要 |
The drill bit (1) has a shaft (3) to be inserted into the chucks of a power drill with one end (7) and a drill head (8) positioned at the opposite end (5). The drill head (8) is provided with three radial positioned slightly helical shaped cutting grooves (10) and three cutting edges (9, 91) extending into three smaller, inclined cutting edges (17), which are part of the centering crest (11). The specific design causes the tip of the drill head (8) to move almost horizontally across the surface of a metal sheet and to avoid to sink in too deeply into the material to be processed. |
