Patent ID: 7704030

Claim:
A screw for use in nonmetal objects comprising: a screw head; a shank longitudinally extending from said screw head along a shank axis; a drilling portion disposed on a distal end of said shank, opposite to said screw head; and a plurality of threads disposed on said shank; wherein a plurality of cut-aiding portions being disposed on said shank and located between any two of said threads, and said cut-aiding portions being adjacent to each other; each of said cut-aiding portions consisting of a longer cutting surface and a shorter cutting surface joined thereto; said longer cutting surface and said shorter cutting surface being positioned toward opposite directions; a cutting edge being formed at an intersect of said shorter cutting surface and said longer cutting surface, whereby said shorter cutting surface and said cutting edge being presented in a fastening direction of said screw; said longer cutting surface comprising a first raked face and a second raked face with different slopes disposed thereon, thus forming a ridge where said first raked face and said second raked face meet; said ridge transversely extending to said shorter cutting surface of said cut-aiding portion.