Drill

Drill comprising a substantially solid shank with a first, tip-forming end having one or more cutting edges for cutting or machining of workpieces for making holes in the workpieces, an opposite second end of the shank and a number of flutes corresponding to the number of cutting edges, said flutes extending from the tip end towards the other end, said flutes being provided for forming and conveying chips from the corresponding cutting edge, said flutes having a first, chip-forming zone extending for a predetermined length from the first end and having one of a predetermined width or cross-sectional area, a second, chip-conveying zone with one of a larger width or cross-sectional area than the first zone at the connection between the first and second zones, the flutes along at least a portion of the second zone having a width that decreases toward the rear end, the chips after being formed in the first zone being capable of dilating in the second zone for reducing the friction-increasing force with which the chips tend to press against internal walls of the flutes and an inner wall of a hole during drilling.

Drill comprising a substantially solid shank with a first, tip-forming end having one or more cutting edges for cutting or machining of workpieces for making holes in the workpieces, an opposite second end of the shank and a number of flutes corresponding to the number of cutting edges, said flutes extending from the tip end towards the other end, said flutes being provided for forming and conveying chips from the corresponding cutting edge, said flutes having a first, chip-forming zone extending for a predetermined length from the first end and having one or a predetermined width or cross-sectional area, a second, chip-conveying zone with one of a larger width or cross-sectional area than the first zone, the chips after being formed in the first zone being capable of dilating in the second zone for reducing the friction-increasing force with which the chips tend to press against internal walls of the flutes and an inner wall of a hole during drilling, along at least a rear portion of the first chip-forming zone, the flutes having a width that gradually decreases rearwards to form a passage with minimal width in the region of the connection between the first and second zones, said passage compressing the chips to an extraordinarily small volume before the chips are fed into the second conveying zone.

Drill comprising a substantially solid shank with a first, tip-forming end having one or more cutting edges for cutting or machining of workpieces for making holes in the workpieces, an opposite second end of the shank and a number of flutes corresponding to the number of cutting edges, said flutes extending from the tip end towards the other end, said flutes being provided for forming and conveying chips from the corresponding cutting edge, said flutes having a first, chip-forming zone extending for a predetermined length from the first end and having one of a predetermined width or cross-sectional area, a second, chip-conveying zone with one of a larger width or cross-sectional area than the first zone, the chips after being formed in the first zone being capable of dilating in the second zone for reducing the friction-increasing force with which the chips tend to press against internal walls of the flutes and an inner wall of a hole during drilling, the shank being divided into a main part and a tip part, which is connectable with the main part, the cutting edges being provided on the tip part, the connection between the chip-forming zone and the chip-conveying zone in each flute being located in the region of the joint between said main part and said tip part.