Two edged drill for high tensile materials - has cutter plate whose edges are axially and positively radially between zero and five degrees

摘要

The two edged drill is for high tensile materials, whose front cutting edge is on or near the drill periphery and whose main cutting edges are inclined inwards where the total cutting width is so split on the two cutting edges that one edge assumes roughly the outer half of the cutting width and the drill guide and the other cutting edge assumes roughly the inner half of the cutting width. The rake angle of the cutter plate edges are axially and radially positively in a range between 0 deg. and 5 deg. and the inner cutting edge lies at least 0.1 to 0.3 mm. below the centre of the drill axis. The drill has internal cooling and lubrication bores which emerge in the free faces near the flutes.