| 摘要 |
The invention relates to a self-tapping screw, whose threads, in a rear area (facing the head), have a substantially cylindrical external diameter and, in a front area (facing away from the head), extend with an external diameter which decreases towards the end of the screw. Both in the rear area and in the front area, the threads have an asymmetrical cross section with a bisector of the flank angle, measured at the thread tips, which is located obliquly with respect to the axial course of the core and which reverses from the rear area (first cross section) towards the front area (second cross section), the bisector in the front area being inclined towards the screw head. The reversal point of the thread cross section is placed such that the first cross section is substantially present in the rear area, the second cross section substantially in the front area. |
