Patent ID: 7134813
Filing Date: 2006-11-14
Classification: B23B,Y10T

Abstract:
1. A rotary driven cutting tool, comprising a drill having a nominal drill diameter D, at least one spiral cutting groove and at least one land which extend from a tool tip of the drill to a tool shaft of the drill, each land comprising a main cutter and an internal cooling channel which extends from the tool tip to an opposite end of the drill and comprises a continuous cross-sectional contour, which tangentially encloses an imaginary circle with a center, the cross-sectional contour of the internal cooling channel comprising at least one curvature maximum whose distance from an axis of the drill in the direction of a line between the center and the axis of the drill exceeds, or is the same as, the distance between the center and the axis of the drill, a minimum wall thickness between the internal cooling channel and an external circumference of the drill being between a lower limit and an upper limit, a minimum wall thickness between the internal cooling channel and a cutting face of the drill being between said lower limit and said upper limit, and a minimum wall thickness between the internal cooling channel and a cutting flank of the drill being between said lower limit and said upper limit, said lower limit being 0.08×D for D<=1 mm, and 0.08 mm for D>1 mm, said upper limit being 0.35×D for D<=6 mm, and 0.4×D−0.30 mm for D>6 mm, a radius at the smallest radius of curvature of the cross-sectional contour of the internal cooling channel corresponding to 0.35 times to 0.9 times a radius of a circle enclosed by the contour.