| 摘要 |
A self-tapping screw (1) for use in fixing insulating boards (4) and waterproof sheeting (3, 3'), to a flat roof sheet panel (2), has a screw head (6), a self-drilling tip (10) and a screw shank which has a self-tapping thread (9) adjoining the self-drilling tip (10) and divided into sections (9/2, 9/3) by at least one smooth shank section (8). A further smooth shank section (7) directly adjoins the screw head (6). The diameter of the smooth shank sections (7, 8) is smaller than the root diameter of the self-tapping thread (9), and the end (15) of each thread section nearest the screw head (6), extends radially inwardly to the screw-shank diameter in the form of a flat radial surface (16) which is free of a thread run-out and is perpendicular to the axis of the screw shank. The screw (1) provides greater reliability against being unintentionally slackened, released and pulled out of its anchorage hole under the typical stresses experienced by flat roofs. |
