| 摘要 |
<p>A blank (100) for a self tapping fastener with a drive head (102), and a corresponding self tapping fastener is provided. The fastener blank has an odd number of lobes in a cross section taken perpendicular to its axis of rotation (112). The lobes define a relatively high out-of-round cross section along an axially tapered thread-forming zone (108), and a relatively low out-of-round cross section along the main body (104) taken in a direction toward the drive head. Between the main body and tapered thread-forming zone is located an additional thread forming zone (110) having an axial length (LA) of approximately one thread pitch and a cross section that conforms to the high out-of-round of the tapered zone. The maximum diameter (at the lobes) of the additional thread-forming section approximately matches that of the full-diameter main body section. A lower-diameter stabilizing section (106) can be provided ahead of the tapered zone, adjacent the tip of the fastener.</p> |
