| 摘要 |
A twist drill has fastening elements and a cutting part comprising helical grooves, and two cutting edges with a radius of curvature of a cutting wedge. The radius of curvature of the cutting wedge is variable along the length of the main cutting edges. The radii of curvature of the main cutting edges on the periphery of the drill are equal to: r= 0,004-0,005. R, mm. The radii of curvature of the edges at a bridge are determined by the formula =r/3, mm. |
