Patent ID: 8596943

Claim:
A chipless thread-forming screw ( 10 ) for securing a stack of a plurality of metal sheets having a total thickness between 2 and 3.1 mm, the screw comprising a shank ( 11 ) carrying, at least regionwise, a thread ( 15 ); a tip region provided at one end of the shank ( 11 ); and a head ( 14 ) provided at another opposite end of the shank ( 11 ), the shank having a frustoconical section ( 21 ) extending from the tip region in direction of the head ( 14 ), and a cylindrical section ( 25 ) extending between the frustoconical section ( 21 ) and the head ( 14 ), wherein the tip region has a shape different from a shape of the frustoconical section ( 21 ) of the shank ( 11 ), a base extending transverse to a screw axis and from which the frustoconical section ( 21 ) extends and which has a diameter between 0.25 and 0.35 mm, and a non-pointed tip ( 13 ) spaced from the base, wherein the frustoconical section ( 21 ) has, with respect to a thread root ( 22 ), a point angle (α) between 20° and 30°, and wherein a starting line ( 23 ) of the thread ( 15 ) remote from the head ( 14 ) is spaced from the tip ( 13 ) by a distance (Lt) from 0 to 0.3 mm.