Patent ID: 6739809
Filing Date: 2004-05-25
Classification: B23B,Y10T

Abstract:
A drill comprising:a cutting point and a body including at least two diametrically opposite flutes, the body including a periphery, a web and lands extending from the web and having margins at leading edges of the lands, wherein the flutes are positioned between the land, the cutting point including a leading cutting lip and a trailing cutting lip and a central â€œs-shapedâ€  chisel edge extending between the leading and trailing cutting lips and defining two symmetrical drill point halves, wherein each drill point half includes a primary relief surface, a secondary relief surface and a third relief surface; the primary relief surface is inclined radially outwardly from the central chisel edge to the periphery of the body and downwardly from the leading cutting lip to the secondary relief surface; the secondary relief is inclined radially outwardly from the central chisel edge to the periphery of the body and downwardly from the primary relief surface to a rake surface of the flute; the third relief surface is inclined radially outwardly from the central chisel edge to the rake surface of the flute and downwardly from the central chisel edge to the secondary relief surface; wherein the third relief surface is inclined at an angle greater than the secondary relief surface and the secondary relief surface is inclined at an angle greater than the primary relief surface; wherein the third relief surface is substantially planar.