| 摘要 |
<p>The screw has an axial channel (4) and a threaded proximal section (1), a smooth intermediate section (2) and a threaded distal section (3). The proximal section is of greater diameter than the distal section, while the latter has two threads (31, 32), each with a pitch (A) at least twice as great as the pitch (B) of the proximal section. The smooth intermediate section of the screw accounts for about a third of its total length and both threaded ends are self-drilling and self-tapping. The proximal and distal threads can be chamfered at different angles, e.g. at 60 and 120 degrees respectively, or at the same angle of 90 degrees.</p> |
