Cutters for fixed cutter bits

Abstract

A PDC cutter including a body formed from a substrate material, an ultrahard layer disposed on the body, and a concave cutting face perpendicular to an axis of the body is disclosed. A PDC cutter including a body formed from a substrate material, an ultrahard layer disposed on the body, and a non-planar cutting face perpendicular to an axis of the body, the cutting face including a circumferential concave portion, and an inner protrusion portion is also disclosed.

1 . A PDC cutter comprising:
 a body formed from a substrate material;   an ultrahard layer disposed on the body; and   a concave cutting face perpendicular to an axis of the body.   
     
     
         2 . The PDC cutter of  claim 1 , wherein a depth of the concave cutting face is less than a height of the ultrahard layer. 
     
     
         3 . The PDC cutter of  claim 1 , wherein a depth of the concave cutting face is between 50 and 85 percent of a height of the ultrahard layer. 
     
     
         4 . The PDC cutter of  claim 1 , wherein a cutting profile of the concave cutting face is asymmetric with respect to the axis of the body. 
     
     
         5 . The PDC cutter of  claim 1 , wherein the body is cylindrical. 
     
     
         6 . The PDC cutter of  claim 1 , wherein the body is oval. 
     
     
         7 .- 25 . (canceled) 
     
     
         26 . The PDC cutter of  claim 1 , wherein a cutting profile of the concave cutting face comprises a linear profile. 
     
     
         27 . The PDC cutter of  claim 1 , wherein a cutting profile of the concave cutting face comprises a rounded profile. 
     
     
         28 . The PDC cutter of  claim 1 , wherein a cutting profile of the concave cutting face comprises a radius of curvature that varies across the concave cutting face. 
     
     
         29 . The PDC cutter of  claim 1 , where a portion of the body is exposed at a deepest point of the concave cutting face. 
     
     
         30 . The PDC cutter of  claim 1 , wherein a deepest point of the concave cutting face is centrally located within the cutting face, along the axis of the body. 
     
     
         31 . A PDC cutter comprising:
 a body formed from a substrate material; and   an ultrahard layer disposed on the body, the ultrahard layer having a cutting face intersecting a circumferential side surface at a cutting edge;   where a cutting edge angle formed between the cutting face and the circumferential side surface is less than 90 degrees.   
     
     
         32 . The PDC cutter of claim  13 , wherein the cutting face is concave. 
     
     
         33 . The PDC cutter of claim  14 , wherein a deepest point of the concave cutting face is centrally located within the cutting face, along a central axis of the body. 
     
     
         34 . The PDC cutter of claim  14 , wherein a deepest point of the concave cutting face is offset from a central axis of the body. 
     
     
         35 . The PDC cutter of claim  13 , wherein the body is cylindrical. 
     
     
         36 . The PDC cutter of claim  13 , wherein the body has an oval cross sectional shape.