| 摘要 |
<p>"A self-threading screw is described which includes a (basically) conical point (7,7') set at the end of its shank (9') opposite that where the head (2) is housed, and a sunken zone (8) set between the end of the screw shank (9') and the conical point (7,7'). In addition, an apparatus is described to produce a self-threading screw provided with a point and a sunken zone, in which at least the thread of the self-threading screw, the conical point and the sunken zone are simultaneously produced by rolling." <IMAGE></p> |
