| 摘要 |
A fastener is constructed having four thread zones (4, 5, 6, 7) constructed over the length of the fastener (1), from the head (2) to the tip (10), namely a ridged cylindrical holding zone (4), a ridged cylindrical transition thread forming zone (5), a rectilobular tapered thread forming zone (6), and a rectilobular alignment zone (7). The pitch cross section of the thread varies in each zone. |
