US Patent 7862280 Saw tooth screw

A saw tooth screw provides a screw thread divided into a first and a second thread sections. A plurality of slots, inclined with respect to a shank axial line, are disposed on each thread of the first thread section for dividing the thread into a plurality of thread segments, wherein each of the thread segment has a first inclined surface and a second inclined surface on two ends thereof; the first inclined surface is parallel to the second inclined surface. The thread of the second thread section is formed of a saw-tooth-shape by having recesses extending from a shank to an outer edge of the thread for debris of object to exit through the slots, thereby reducing the screwing torsion and increasing the screwing rotation speed.