FASTENER

摘要

A fastener comprises a shank defining a shank root, a head, a drilling portion and main threads. Each of the main threads is inclined with respect to a shank axis by 60-82 degrees. At least one main lobe projects from the shank. The main lobe is extended outwards from the shank root and attached to at least one cutting face of each main thread. Accordingly, the inclining arrangement allows the main threads to have a large rotating angle at the time of drilling and increase the drilling speed. By the main lobe in connection with the main thread, the fastener attains the preferable torque and flexibility, enhances the torsion resistance and the tensile strength against the drilling stress to prevent the fastener from snapping and reduces the resonant vibratory effect caused by vibrations after the drilling action, thereby promoting a firm fastening effect.

主权项

1. A fastener comprising:
a shank defining a shank root; a head disposed on one end of said shank; a drilling portion disposed on the other end of said shank; and a plurality of main threads spirally disposed on said shank, each of said main threads comprising two inclined cutting faces connected with each other; wherein each of said main threads is inclined with respect to a shank axis by 60-82 degrees, at least one main lobe projecting from said shank, said main lobe being extended outwards from said shank root and attached to at least one cutting face of each of said main threads.