| 摘要 |
A chipless thread-forming screw (10) has a thread-carrying shank (11) provided at its opposite ends with a tip (13) and a head (4), respectively, and having a diameter between .25 and .35 mm, with the shank (11) having at least one frustroconical section (21) extending from the tip (13) in directi on of the head (14) and having, with respect to the thread root (22), a point angl e (.alpha.) between 20.degree. and 30.degree., and a cylindrical section (25) extending between the frustroconical section (21) and the head (14), and with a starting line (23) of the thread (15) remote from the head (14) being spaced from the tip (13) by a distance (L t) from 0 to .3 mm.
|
