| 摘要 |
The invention relates to a screw ( 1 ) having a threaded shank ( 2 ) and a screw tip ( 6 ). The threaded shank ( 2 ) is composed of a shank core ( 10 ) and a thread which extends helically over the shank core ( 10 ). Two flanks ( 15, 16 ) which converge in an outer thread edge ( 14 ) has a height (H) measured radially from the shank core ( 10 ) to the thread edge ( 14 ). The thread ( 12 ) has a specific apex angle (alpha) formed between the adjacent flanks ( 15, 16 ). Preferably the outer thread edge ( 14 ) extends in a wave form in the radial direction with an amplitude (U) between wave crests ( 20 ) forming indentations ( 24 ) which interrupt the surface of the flank ( 15/16 ). At least one of the two flanks ( 15, 16 ) of the thread ( 12 ) is formed concavely in the region between the shank core ( 10 ) and the thread edge ( 14 ), seen in radial profile, in such a way that the apex angle (alpha) is less than a flank angle (alpha<SUB>F</SUB>). With preference, the thread ( 12 ) respectively has in the regions that are not interrupted by indentations ( 24 ). |
