| 摘要 |
Fasteners are provided that include a head and having a head, a tip end having a tip, a first body portion having right-hand threads, and a second body portion having left-hand threads. The first body portion is adjacent to the tip end of the fastener and extends a first distance along a length of the fastener towards the head end. The second body portion is adjacent to the first body portion, and extends the head end of the fastener and extending a second distance along the length of the fastener towards the head end. The right-hand threads, and the left-hand threads, can have a pitch angle .alpha. of less than about 60°. |
