| 摘要 |
PCT No. PCT/EP98/04720 Sec. 371 Date Jun. 21, 1999 Sec. 102(e) Date Jun. 21, 1999 PCT Filed Jul. 28, 1998 PCT Pub. No. WO99/06719 PCT Pub. Date Feb. 11, 1999A 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 Q1=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 DEG ; 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 2.7; 3) the point angle of the thread teeth is about 30 DEG . |
