Patent ID: 6655882
Filing Date: 2003-12-02
Classification: B22F,C22C,Y10S,Y10T

Abstract:
A twist drill having a central longitudinal axis, said twist drill comprising:a cutting tip being configured to impact a material to be drilled to initiate drilling of the material; a shank portion being configured to be inserted into and held in a chucking arrangement for a drill; a fluted portion being disposed between and to connect said tip portion and said shank portion; said fluted portion comprising: a first chip flute and a second chip flute; said first chip flute and said second chip flute being substantially symmetric with respect to one another and substantially helically disposed about said central longitudinal axis; a first cutting edge being disposed between said cutting tip and said first chip flute; a second cutting edge being disposed between said cutting tip and said second chip flute; 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 helically along said fluted portion from said first cutting edge; said second chip flute being disposed to extend helically along said fluted portion from said second cutting edge; at least a portion of said cutting tip and at least a portion of said fluted portion comprise a tool portion having an interior and an exterior; and said tool portion comprising: a cermet body configured to engage material to remove or dislodge material; said cermet body comprising at least one hard component and a binder; said binder comprising: cobalt in the range of from about forty weight percent to about ninety weight percent; nickel in the range of from about four weight percent to about thirty-six weight percent; and iron in the range of from about four weight percent to about thirty-six weight percent; said binder having a ratio of nickel to iron in the range of about 1.5:1 to about 1:1.5; said binder in said body having a first concentration at a first portion and a second concentration at a second portion; said first concentration in said first portion being substantially different from said second concentration in said second portion to thus form a gradient in said body; said binder comprising a substantially face centered cubic structure, with the difference in concentration between said first concentration and said second concentration of said binder in said body being configured and disposed to substantially maintain said face centered cubic structure of said binder upon said binder being subjected to plastic deformation; and the difference in concentration between said first concentration and said second concentration of said binder in said body also being configured and disposed to minimize stress and strain induced transformations in said binder, and to maximize fatigue resistance and toughness in said body.