Rotary cutting tool having pcd cutting tip

Abstract

A method of forming a cutting tool includes: providing a PCD coated nib of material formed in the shape of a rotary cutting tip; brazing the nib onto a generally cylindrical rod member disposed about a central longitudinal axis, the generally cylindrical rod member having a number of coolant passages formed therein at a first helix angle relative to the central longitudinal axis; and grinding a number of differential flutes of varying helix angles with respect to the central longitudinal axis into the brazed cylindrical rod and nib, each differential flute being oriented such that a corresponding coolant passage of the number of coolant passages breaks out within a corresponding flute.

1 - 6 . (canceled) 
     
     
         7 . A method of forming a cutting tool, the method comprising:
 providing a PCD coated nib of material formed in the shape of a rotary cutting tip;   brazing the nib onto a generally cylindrical rod member disposed about a central longitudinal axis, the generally cylindrical rod member having a number of coolant passages formed therein at a first helix angle relative to the central longitudinal axis; and   grinding a number of differential flutes of varying helix angles with respect to the central longitudinal axis into the brazed cylindrical rod and nib, each differential flute being oriented such that a corresponding coolant passage of the number of coolant passages breaks out within a corresponding flute.   
     
     
         8 . The method of  claim 7  wherein each differential flute includes a first portion disposed at or about the first helix angle with respect to the central longitudinal axis, a second portion disposed at a second helix angle with respect to the central longitudinal axis, and a third portion disposed at third helix angle with respect to the central longitudinal axis; wherein the third portion is disposed between the first and second portions along the central longitudinal axis; and wherein the third helix angle is greater than the first helix angle. 
     
     
         9 . The method of  claim 8  wherein each coolant passage of the number of coolant passages breaks out into a respective flute of the number of differential flutes generally in the third portion of the respective flute. 
     
     
         10 . The method of  claim 7  wherein grinding each flute of the number of differential flutes comprises:
 grinding a first portion at the first helix angle, 
 grinding a third portion adjacent the first portion at a third helix angle, and 
 grinding a second portion adjacent the third portion and opposite the first portion at a second helix angle, wherein the third helix angle is greater than the first portion. 
 
     
     
         11 . The method of  claim 10  wherein the first helix angle comprises an angle of about 30 degrees. 
     
     
         12 . The method of  claim 10  wherein the third helix angle comprises an angle of about 45 degrees. 
     
     
         13 . The method of  claim 10  wherein the second helix angle comprises an angle in the range of about 15 degrees to about 20 degrees.