| 摘要 |
<p>A drilling and thread forming fastener is provided having a threaded shank and a pilot end. The fastener pilot end in cross section has a major and minor axis intersecting at the fastener center of rotation. A pair of arcuate flutes are disposed in opposed quadrants from a pair of arcuate lands, each of said arcuate flutes and an arcuate land intersecting on the major axis to form a cutting edge of the fastener, the two cutting edges being disposed in a plane containing the center of rotation of the fastener. The fastener construction is adaptable to applications in relatively thick materials including cement or cinder block, and is effective to increase tool life when manufactured by a forging process.</p> |
