| 摘要 |
A twist drill for drilling composite materials includes a shank; a drill body; a drill tip having a cutting edge, a chisel edge, and a secondary chisel edge, wherein the secondary chisel angle of the drill tip is 145° to 165 and the point angle is 70° to 100°; and a flute extending from the drill tip to the drill body. The flute has a constant helix, and the helix angle of the flute being selected from the range 45° to 55°. A method of drilling a composite material comprising fibers uses the twist drill of the present embodiment. Suitably, the composite material is carbon fiber reinforced plastic or glass fiber reinforced plastic, and optionally being a laminate material such that the method comprises stack drilling. Embodiments achieve a combination of good hole quality, good tool life and good hole size spread. |
