| 摘要 |
The bit 1 includes a shaft 2, a blade 8 attached to the shaft, a cutting edge 18 & 20 formed on the blade and a smooth flute 50 & 52 formed in the blade adjacent to the cutting edge. The blade may have a pair of cutting shoulders 14 & 16 that extend inwardly from the outer sides of the blade toward a bit axis A. A tip 26 has converging sides 28 & 30 that create a point 32 that extends from the shoulders 14 & 16. The flute 50 & 52 may be provided on the leading portion of each blade face 10 & 12 adjacent the cutting edges 18 & 20. Each flute is a smooth curve that creates a substantially uninterrupted recess on each face of the blade to facilitate chip removal, increase the drill rate and lower the power required to drill a hole. The flute may have two curved surfaces with different radii of curvature. A non-stick coating may be applied to the blade to further facilitate chip removal. |
