Abstract: A cold-rolled screw which is intended for screwing into plastic has a narrow self-tapping thread with an inflection on at least one side of the thread so that the inner flank angle is smaller than the outer flank angle but still approximately equal to or larger than one third of the outer flank angle. In a second aspect, the screw thread has an end surface spaced from the free end of the screw to guide the plastic displaced by the thread during threading of the screw.

Abstract: A cold-rolled screw which is intended for screwing into plastic has a narrow self-tapping thread with an inflection on at least one side of the thread so that the inner flank angle is smaller than the outer flank angle but still approximately equal to or larger than one third of the outer flank angle. In a second aspect, the screw thread has a end surface spaced from the free end of the screw to guide the plastic displaced by the thread during threading of the screw.

Abstract: A retaining screw produced by cold rolling includes a self tapping thread designed to be screwed into thermoplastic material or the like. The screw has a virtually end-to-end cylindrical thread as well as thread teeth, the thread crest of which has the same height on the whole length, while the free space between two teeth remains the same all along the thread The screw presents the following characteristics: either 1) the thread outer diameter Do and the thread inner diameter Dk represent the ratio Q.sub.1 =Do/Dk, in a magnitude of 1.2 to 1.4; 2) the axial distance P between two thread teeth gives with the height H of the latter a ratio Q2=P/H, in a magnitude of 2.75 to 2.9; 3) the point angle of the thread teeth is about 30.degree.; or 1) the thread outer diameter Do and this thread inner diameter gives a ratio Q1=Do/Dk, in a magnitude of 1.25 to 1.65; 2) the axial distance P between two thread teeth gives with the height H of the latter a ratio Q2=P/H, in a magnitude of 2.35 to 2.