Rotary cutting bit with material-deflecting ledge

Abstract

A cutting bit includes a body having a front surface and a side surface, the side surface including a shoulder below the front surface and extending substantially perpendicular to a central axis of the body, and a ring that is harder than the body attached to the body at a front surface of the shoulder. Wear life of the cutting bit is enhanced by maintaining particular dimensional relationships regarding the position of the ring on the body, and the diameter of portions of the body.

1 . A cutting bit, comprising: 
 a body having a front surface and a side surface, the side surface including a shoulder below the front surface and extending substantially perpendicular to a central axis of the body, the body being no larger in diameter above the shoulder than at the shoulder; and    a ring that is harder than the body attached to the body at a front surface of the shoulder.    
   
   
       2 . The cutting bit as set forth in  claim 1 , further comprising a cutting tip attached to the front surface, the cutting tip being harder than the body.  
   
   
       3 . The cutting bit as set forth in  claim 1 , wherein the body includes a second shoulder below the first shoulder, the body being no larger in diameter above the second shoulder than at the second shoulder, and the cutting bit comprising a second ring attached to the body at a front surface of the second shoulder.  
   
   
       4 . The cutting bit as set forth in  claim 1 , wherein a distance between the front surface and a top of the ring divided by a distance between the front surface and a bottom surface of the body is 0.15 to 0.5.  
   
   
       5 . The cutting bit as set forth in  claim 1 , further comprising a cutting tip attached to the front surface.  
   
   
       6 . The cutting bit as set forth in  claim 5 , wherein a diameter of a bottom of the cutting tip divided by the diameter of the body at the bottom of the cutting tip is 0.72 to 0.95.  
   
   
       7 . The cutting bit as set forth in  claim 5 , wherein a diameter of the cutting tip divided by an outside diameter of the ring is 0.60 to 0.80.  
   
   
       8 - 23 . (canceled)  
   
   
       24 . A cutting tip for being attached to a cutting bit, comprising: 
 a base portion,    a tip portion, the tip portion being generally convex in shape; and    a side portion extending between the base portion and the tip portion, the side portion being generally concave in shape.    
   
   
       25 - 32 . (canceled)