| 摘要 |
A self-drilling, self-tapping screw has a drill tip formed by a pair of conical segments 24, 26. Each segment has a flat side and a rounded tip with one segment being longitudinally off set with respect to the other. The shorter segment 26 may have a greater inclined angle. The flat side of the second segment is coplanar with the flat side of the first segment. The screw preferably includes a quad-lead thread 18, 20 having two crests with a first diameter and two crests with a second larger diameter. Other threads may be used. <IMAGE> |
