| 摘要 |
<p>A drilling and thread forming screw is provided with means for breaking the chips produced during the drilling process. An obstruction in the form of a truncated cylindrical element having its flat end portion substantially facing the cutting edge of the cutting surface and having its cylindrical centerline perpendicular to the cutting edge is provided on the cutting surface whereby a chip formed by the drilling process is turned back into a sharp radius, causing the chip to break.</p> |
