Patent ID: 6071046
Filing Date: 2000-06-06
Classification: B23B,Y10T

Abstract:
A drilling head having a cylindrical body with a longitudinal axis, tapering towards a leading end thereof, said drilling head comprising at least two chip evacuation flutes and at least two lands therebetween;each flute having a first side wall facing the direction of rotation of the drilling head and a second side wall diverging outwardly from the first side wall and merging therewith, adjacent the leading end of the drilling head, via a web-thinning recessed surface extending towards said leading end;each land being bound by said first wall of one adjacent flute and said second wall of another adjacent flute and having a generally radially extending and axially inclined front flank face tapering towards said leading end; said front flank face of each land intersecting the first wall of said one flute at a primary cutting edge, intersecting the web-thinning recessed surface of said one flute at a secondary cutting edge, and intersecting the front flank face of the other land at a chisel edge which is disposed at the leading end of the drilling head and which passes through said longitudinal axis;characterized in that said chisel edge is concave and merges with the secondary cutting edges of the two lands via axially outermost extremities thereof which are spaced from said axis, and whereinan axially innermost point of the chisel edge divides the chisel edge into two chisel edge cutting sections, and the chisel edge is provided with recesses formed in the front flank faces of the lands and extending away therefrom, each recess providing one chisel edge cutting section with a chip rake surface and the other chisel edge cutting section with a relief surface.