Patent ID: 8668409
Filing Date: 2014-03-11
Classification: B23B,B23C,Y10T

Abstract:
1. A twist drill comprising: a drill body of generally cylindrical shape disposed about a longitudinal axis, the drill body having a first end configured to be coupled to a machine tool and an opposite second end, the drill body including a chip flute formed therein, the chip flute extending a distance along the drill body, the chip flute having a leading edge and a run-out edge running along the chip flute, the run-out edge disposed behind the leading edge in a direction of rotation of the twist drill, wherein: the chip flute, viewed cross-sectionally in a direction perpendicular to the longitudinal axis, includes a first wall portion and a second wall portion, the first wall portion extends along a curve between the run-out edge and the second wall portion, the second wall portion extends in a straight line from between the leading edge and the first wall portion, the first wall portion and the second wall portion are disposed adjoining one another and together define a J-shaped cross-sectional profile perpendicular to the longitudinal axis, and the first wall portion has a curvature such that an acute advance angle is formed between a first line and a second line, the first line being tangential to the first wall portion at the run-out edge and the second line extending: