Patent ID: 7682119
Filing Date: 2010-03-23
Classification: F16B

Abstract:
1. A screw comprising: a shank portion including a tapered bottom section having a tip; a head on top of said shank portion; a first helical thread extending helically around said shank portion in a first direction between said tip and said head, and having a first end distal from said head, and a second end opposite to said first end; a second helical thread extending helically around said shank portion in a second direction between said first helical thread and said tip, and having a third end proximate to said first end of said first helical thread, said first and second directions being opposite to each other; and a non-helical first ridge extending around said shank portion between said first and second helical threads and having a major diameter substantially identical to that of each of said first and second helical threads, said non-helical first ridge including a single non-helical crest extending around said shank portion, and two inclined faces tapering from said single non-helical crest in opposite directions; wherein said inclined faces of said first ridge are respectively in contact with said first end of said first helical thread and said third end of said second helical thread.