| 摘要 |
<p>A screw capable of drilling holes easily and discharging dregs effectively includes a head; and a stem extending from a lower portion of the head. The head is formed by an upper portion and a lower portion. The upper portion is a round disk. The annular ring of the round disk of the head is formed with a plurality of inclined protrusion. The recesses between the protrusions extend from an inner edge of the round ring to an outer edge of the round ring and are arranged along un-radial paths. A periphery of the lower portion of the head is formed with at least one knife sheet which extends from the annular ring of the round disk of the head to the stem; and the direction of the knife sheet is inclined to an axis of the lower portion of the head.</p> |
