| 摘要 |
Screw for hard materials such as concrete or masonry comprises a screw shaft, a screw head in the region of one end of the screw shaft, a front screw end, and a thread having cutting teeth alternately arranged to the left and the right of an imaginary central line on the side facing away from the head. Preferred Features: The thread has a saw tooth profile and a series of laterally offset adjacent teeth (7). |
