Patent ID: 8206067

Claim:
A drill bit comprising a shank, a body in the form of a truncated cone extending as far as the shank and the base of which is located at a free axial end of the drill bit, said end having at least two main cutting edges joined together by two central edges, said body having two lips and two flutes extending in a helical fashion alternately around a longitudinal rotation axis of the drill bit, the lips and the flutes extending from the free axial end to the shank of the drill bit, each lip having a land and each flute having a main cutting face adjacent a land and adjacent a main cutting edge, said main cutting edge forming an intersection with a flank face at the free axial end of the drill bit, the flank faces each being extended, on the side with the lips, by a rake face, two recesses extending from the central edges to the periphery of the drill bit and forming two secondary cutting faces, at least one end portion of the body of the drill bit being made of a ceramic, wherein each land is radially extended, toward the rotation axis of the drill bit, by a curved bevel, followed by a flank face, such that the intersection between each curved bevel and the adjacent flute is formed by an edge whose radially external end is further away axially, along the rotation axis of the drill bit, from the shank of the drill bit than a radially internal end of said edge, and wherein the curved bevels are each extended, on the side with the rake faces, by a bevel.