摘要 |
A thread-forming screw includes a head and a shank, the shank having a thread and a thread-forming zone at the end opposite to the head, the thread-forming zone also having a thread portion. The shank at the end opposite to the head has a spherical portion with a maximum diameter in a plane perpendicular to the axis of the shank which corresponds approximately to the mean diameter of the thread of the shank. |