| 摘要 |
A thread-tapping thread (21), which extends at least partially along a stem (12), includes side flanks (23,24) that mutually define an angle (W) of 100 to 350 degrees. The ratio of the outer diameter of the thread with respect to the root diameter of the stem ranges from 1.1 to 1.4. The ratio of the outer diameter of the thread with respect to the pitch (P) of the thread ranges from 1.4 to 1.7. |
