Patent ID: 6309149
Filing Date: 2001-10-30
Classification: B23B,Y10T

Abstract:
A twist drill for dry drilling, said drill comprising:a tip portion;a body portion disposed adjacent said tip portion;a central longitudinal axis;said tip portion being substantially cone-shaped;said tip portion having a base portion and a top portion;said base portion being substantially wider than said top portion;said base portion being disposed immediately adjacent said body portion of said drill;said top portion being disposed on said tip portion opposite said base portion;said tip portion comprising:a first chip face forming a portion of said conical surface of said tip portion;a second chip face forming a portion of said conical surface of said tip portion;a chisel edge arrangement configured to initiate dry cutting of a metal object to be dry drilled;said chisel edge arrangement being disposed between said first chip face and said second chip face;said first chip face having a first end disposed adjacent said chisel edge arrangement and a second end disposed opposite said first end and adjacent said body portion of said drill;said second chip face having a first end disposed adjacent said chisel edge arrangement and a second end disposed opposite said first end and adjacent said body portion of said drill;said first chip face being configured to extend monotonically away from said body portion to said chisel edge arrangement disposed on said top of said tip portion;said second chip face being configured to extend monotonically away from said body portion to said chisel edge arrangement disposed on said top of said tip portion;said first chip face being disposed to meet said second chip face at said top of said tip portion; andsaid chisel edge arrangement comprising:a first chisel edge portion;a second chisel edge portion;each of said chisel edge portions being disposed to extend away from each other from said central longitudinal axis; andsaid first chisel edge portion and said second chisel edge portion being asymmetric with respect to one another about said central longitudinal axis;said body portion comprising:a first chip flute;a second chip flute; andsaid first chip flute and said second chip flute being symmetric with respect to one another about said central longitudinal axis;a first cutting edge, configured to dry drill, being disposed between said tip portion and said body portion;a second cutting edge, configured to dry drill, being disposed between said tip portion and said body portion;said first cutting edge and said second cutting edge being substantially symmetric with respect to one another about said central longitudinal axis;said first chip flute being disposed to extend along said body portion from said first cutting edge; andsaid second chip flute being disposed to extend along said body portion from said second cutting edge.