Screw with low drilling resistance
A screw with low drilling resistance comprises a head portion, a shank portion, a plurality of first threads, a drilling portion, and a plurality of second threads. Wherein, a plurality of opening slots are correspondingly defined on the second threads, and a first included angle of the first threads is smaller than a second included angle of the second threads. Thereby, the opening slots on the second threads efficiently provide the first threads with an auxiliary cutting effect and preferably offers a debris accommodating room. The first threads including the smaller first included angle favorably reinforce the bearing force of the second threads including the larger second included angle, thereby promoting the cutting effect of the screw and allowing a speedy screwing.
1. A screw with low drilling resistance, comprising:
a head:
a shank extended from said head;
a plurality of first threads spiraling on said shank;
a drilling portion disposed on said shank opposite to said head; wherein each first thread includes a first upper flank and a first lower flank connected to said first upper flank; said first upper flank and said first lower flank extending radially from said shank to converge at a first included angle;
a plurality of second threads being affixed to said threads and spiraled on said shank and being respectively disposed on said first upper flank and said first lower flank of said first threads; each second thread including a second upper flank and a second lower flank connected to the second upper flank;
a plurality of connective opening slots being defined by said plurality of second threads, said plurality of connective opening slots exposing portions of said first threads therethrough, said second upper flank and said second lower flank extending radially from said shank to converge at a second included angle, and said first included angle of said first thread being less than said second included angle of said second thread; and
said first upper flank, said first lower flank, said second upper flank and said second lower flank converging to a singular apex point;
whereby said difference in said first and second included angles provide an increased volume within each of said plurality of connective opening slots for receiving debris.