Patent ID: 9539653
Date: 2017-01-10
CPC Classifications: B23B,Y10T

Claim:
1. A twist drill comprising a shank and a flute portion which extends between a drill tip and the shank and has at least two flutes which peripherally extend helically at a twist angle and which are separated from each other by two webs and have a land extending at a periphery of the flute portion between the flutes, wherein provided on each land are at least two respective mutually spaced margins which extend on the land at an angle of inclination relative to a drill axis, that is larger than the twist angle but less than 90°, wherein the twist angle and the angle of inclination are measured from the drill axis in the same direction, and wherein the diameter of the flute portion, defined by the margins, starting from the drill tip, continuously narrows within a distance (A) from the drill tip towards the shank.