Radial cutter bit with cutting insert having edge preparation

Abstract

A radial cutter bit includes a non-rotatable shank portion, a head portion including a tip region distal from the non-rotatable shank portion, and a cutting insert mounted at the tip region of the head portion. The cutting insert includes a body having a leading face, an opposing trailing face, a first side and a second side. The leading face has a central face portion, a first side face portion extending toward the first side of the body and a second face portion extending toward the second side of the body. The cutting insert further includes a top surface having a relief surface, a T-land surface extending between at least a portion of the leading face and the relief surface of the top surface and a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.

What is claimed is: 
     
         1 . A radial cutter bit for engaging an earth strata material, the radial cutter bit comprising:
 a non-rotatable shank portion;   a head portion integrally formed with the non-rotatable shank portion and including a tip region distal from the non-rotatable shank portion; and   a cutting insert mounted at the tip region of the head portion, wherein the cutting insert comprises:
 a body having a leading face, an opposing trailing face, a first side and a second side; 
 the leading face having a central face portion, a first side face portion extending toward the first side of the body and a second face portion extending toward the second side of the body; 
 a top surface having a relief surface; 
 a T-land surface extending between at least a portion of the leading face and the relief surface of the top surface; and 
 a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface. 
   
     
     
         2 . The radial cutter bit of  claim 1 , wherein the T-land surface includes a central T-land surface extending between the central face portion of the leading face and the relief surface of the top surface. 
     
     
         3 . The radial cutter bit of  claim 2 , wherein the cutting edge includes a central cutting edge formed at the intersection of the central T-land surface and the relief surface of the top surface. 
     
     
         4 . The radial cutter bit of  claim 3 , wherein the central cutting edge has a negative axial rake angle. 
     
     
         5 . The radial cutter bit of  claim 1 , wherein the T-land surface includes a first side T-land surface extending between the first side face portion of the leading face and the relief surface of the top surface. 
     
     
         6 . The radial cutter bit of  claim 5 , wherein the cutting edge includes a first side cutting edge formed at the intersection of the first side T-land surface and the relief surface of the top surface. 
     
     
         7 . The radial cutter bit of  claim 6 , wherein the first side cutting edge has a negative axial rake angle. 
     
     
         8 . The radial cutter bit of  claim 1 , wherein the T-land surface includes a second side T-land surface extending between the second side face portion of the leading face and the relief surface of the top surface. 
     
     
         9 . The radial cutter bit of  claim 8 , wherein the cutting edge includes a second side cutting edge formed at the intersection of the second side T-land surface and the relief surface of the top surface. 
     
     
         10 . The radial cutter bit of  claim 9 , wherein the second side cutting edge has a negative axial rake angle. 
     
     
         11 . A cutting insert for use in connection with a cutter bit for engaging an earth strata material, the cutting insert comprising:
 a body having a leading face, an opposing trailing face, a first side and a second side;   the leading face having a central face portion, a first side face portion extending toward the first side of the body and a second face portion extending toward the second side of the body;   a top surface having a relief surface;   a T-land surface extending between at least a portion of the leading face and the relief surface of the top surface; and   a cutting edge formed at the intersection of the T-land surface and the relief surface of the top surface.   
     
     
         12 . The cutting insert of  claim 11 , wherein the T-land surface includes a central T-land surface extending between the central face portion of the leading face and the relief surface, the cutting edge includes a central cutting edge formed at the intersection of the central T-land surface and the relief surface, and the central cutting edge has a negative axial rake angle. 
     
     
         13 . The cutting insert of  claim 12 , wherein the T-land surface includes a first side T-land surface extending between the first side face portion of the leading face and the relief surface, the cutting edge includes a first side cutting edge formed at the intersection of the first side T-land surface and the relief surface, and the first side cutting edge has a negative axial rake angle. 
     
     
         14 . The cutting insert of  claim 13 , wherein the T-land surface includes a second side T-land surface extending between the second side face portion of the leading face and the relief surface, the cutting edge includes a second side cutting edge formed at the intersection of the second side T-land surface and the relief surface, and the second side cutting edge has a negative axial rake angle. 
     
     
         15 . The cutting insert of  claim 12 , wherein the negative axial rake angle of the central cutting edge is in the range of about 10 degrees to about 60 degrees. 
     
     
         16 . The cutting insert of  claim 13 , wherein the negative axial rake angle of the first side cutting edge is in the range of about 10 degrees to about 60 degrees. 
     
     
         17 . The cutting insert of  claim 14 , wherein the negative axial rake angle of the second side cutting edge is in the range of about 10 degrees to about 60 degrees.