| 摘要 |
Thread-forming screw comprising a head and a shank, the shank having a threa d and a thread-forming zone at the end opposite to the head, the thread-formin g zone also having a thread portion, characterized in that the shank at the en d 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 th e mean diameter of the thread of the shank. |
