Patent ID: 9597735
Date: 2017-03-21
CPC Classifications: B23B,B23P,B24B,Y10T

Claim:
1. A twist drill for drilling composite materials, the twist drill comprising: a shank; a drill body; a drill tip including a cutting edge and at least two chisel edges, the at least two chisel edges comprising a primary chisel edge and a secondary chisel edge, wherein the secondary chisel edge has a secondary chisel angle of 145° to 165°, the drill tip also having a point angle of 70° to 100° and a primary facet extending behind the cutting edge and a secondary facet extending behind the primary facet, wherein a relief angle of the primary facet is 15° to 25°, and a relief angle of the secondary facet is 15° to 30°; and a flute extending from the drill tip to the drill body, the flute having a constant helix, and a helix angle of the flute being selected from the range 45° to 55°.