| 摘要 |
<p>The screw is provided with a three-lobed thread and has a tip portion, followed by a threaded intermediate portion with a three-lobed thread geometry, which passes into a further threaded portion that has a circular thread geometry. In all three threaded portions the flank angle of the thread is 60.degree. and the flank angle of the thread crests extending beyond the nominal diameter of the screw is 30.degree..</p> |
