Cutting elements having cutting edges with continuous varying radii and bits incorporating the same

Abstract

A cutting element is provided having a substrate and an ultra hard material cutting layer over the substrate. The cutting layer includes a surface portion for making contact with a material to be cut by the cutting element. The surface portion in cross-section has a curvature that has a varying radius of curvature. A bit incorporating such a cutting element is also provided.

What is claimed is: 
     
       1. A shear cutter type cutting element comprising:
 a substrate for mounting on a drag bit; and 
 an ultra hard material cutting layer over the substrate, said cutting layer comprising a surface portion for making contact with a material to be cut by said cutting element, said surface portion in cross-section having a varying curvature that is formed by a plurality of adjacent sections, each section having a different radius of curvature than its adjacent section, wherein the surface portion in cross-section comprises a first section adjacent to a second section which is adjacent a third section, wherein the first section is non-flat and comprises a first radius of curvature, wherein the third section is non-flat and comprises a third radius of curvature, wherein the second section is flatter than the first and third sections and wherein the third radius of curvature is greater than the first radius of curvature, wherein the cutting layer comprises a first surface interfacing with the substrate and a second surface opposite the first surface, wherein the first section extends from the second surface. 
 
     
     
       2. The cutting element as recited in  claim 1 , wherein the first and third sections curve in the same direction in cross-section. 
     
     
       3. The cutting element as recited in  claim 1 , wherein one of the first and third sections curves in a first direction, and wherein the other of the first and third sections curves in a second direction opposite the first direction. 
     
     
       4. The cutting element as recited in  claim 1 , wherein the second section is flat. 
     
     
       5. The cutting element as recited in  claim 1 , wherein the surface portion in cross-section defines a chamfer. 
     
     
       6. The cutting element as recited in  claim 1 , wherein the surface portion extends from a peripheral surface of the cutting layer. 
     
     
       7. The cutting element as recited in  claim 1 , wherein the cutting layer comprises a first surface interfacing with the substrate, a second surface opposite the first surface, and a peripheral surface between the first and second surfaces, wherein the third section extends from the peripheral surface. 
     
     
       8. The cutting element as recited in  claim 1 , wherein the surface portion in cross-section comprises at least 35 sections, each section having a different radius of curvature than its adjacent section. 
     
     
       9. The cutting element as recited in  claim 1 , wherein the second radius of curvature is greater than the third radius of curvature. 
     
     
       10. The cutting element as recited in  claim 9 , wherein the second radius of curvature is greater than the first radius of curvature. 
     
     
       11. A shear cutter type cutting element comprising:
 a substrate for mounting on a drag bit; and 
 an ultra hard material cutting layer over the substrate, said cutting layer comprising a surface portion for making contact with a material to be cut by said cutting element, said surface portion in cross-section having a varying curvature that is formed by a plurality of adjacent sections, each section having a different radius of curvature than its adjacent section, wherein the surface portion in cross-section comprises a first section adjacent to a second section which is adjacent a third section, wherein the first section is non-flat and comprises a first radius of curvature, wherein the third section is non-flat and comprises a third radius of curvature, wherein the second section is flatter than the first and third sections and wherein the third radius of curvature is greater than the first radius of curvature, wherein the cutting layer comprises a first surface interfacing with the substrate, a second surface opposite the first surface, and a peripheral surface between the first and second surfaces, wherein the third section extends from the peripheral surface. 
 
     
     
       12. The cutting element as recited in  claim 11 , wherein the first and third sections curve in the same direction in cross-section. 
     
     
       13. The cutting element as recited in  claim 11 , wherein one of the first and third sections curves in a first direction, and wherein the other of the first and third sections curves in a second direction opposite the first direction. 
     
     
       14. The cutting element as recited in  claim 11 , wherein the second section is flat. 
     
     
       15. The cutting element as recited in  claim 11 , wherein the surface portion in cross-section defines a chamfer. 
     
     
       16. The cutting element as recited in  claim 11 , wherein the surface portion in cross-section comprises at least 35 sections, each section having a different radius of curvature than its adjacent section. 
     
     
       17. The cutting element as recited in  claim 11 , wherein the second radius of curvature is greater than the third radius of curvature. 
     
     
       18. The cutting element as recited in  claim 17 , wherein the second radius of curvature is greater than the first radius of curvature. 
     
     
       19. A shear cutter type cutting element comprising:
 a substrate for mounting on a drag hit; and 
 an ultra hard material cutting layer over the substrate, said cutting layer comprising a surface portion for making contact with a material to be cut by said cutting element, said surface portion in cross-section having a varying curvature that is formed by a plurality of adjacent sections, each section having a different radius of curvature than its adjacent section, wherein the surface portion in cross-section comprises a first section adjacent to a second section which is adjacent a third section, wherein the first section is non-flat and comprises a first radius of curvature, wherein the third section is non-flat and comprises a third radius of curvature, wherein the second section is flatter than the first and third sections and wherein the third radius of curvature is greater than the first radius of curvature, wherein the surface portion in cross-section comprises at least 35 sections, each section having a different radius of curvature than its adjacent section. 
 
     
     
       20. The cutting element as recited in  claim 19 , wherein the second section is flat. 
     
     
       21. A shear cutter type cutting element, comprising:
 a substrate; and   an ultrahard layer on an end face of the substrate, the ultrahard layer including:
 a central longitudinal axis; 
 a cylindrical peripheral side surface extending longitudinally from the substrate such that the central longitudinal axis extends longitudinally at a center of the cylindrical peripheral side surface of the ultrahard layer and the substrate; and 
 a cutting surface at an upper end of the ultrahard layer, opposite the substrate and intersecting the central longitudinal axis, extending to the cylindrical peripheral side surface and forming a cutting edge at its periphery, 
 wherein the cutting surface has more than two sections of varying radius of curvature along a plane in which the central axis lies, the more than two sections located circumferentially around the cutting surface and being spaced apart from one another, with a section of non-varying radius of curvature being therebetween; and 
 wherein the varying radius of curvature are selected from flat and convex sections. 
   
     
     
       22. The cutter of claim 21, wherein the varying radius of curvature include at least one convex section abutting to at least one flat section. 
     
     
       23. The cutter of claim 21, wherein the variance in the radius of curvature terminates at a point along the cutting surface a distance from a circumferential surface of the ultrahard layer. 
     
     
       24. The cutting element of claim 21, wherein a portion of the cutting surface, in cross-section, has a flat section. 
     
     
       25. The cutting element of claim 21, where the cutting surface is free of any sharp edges in cross-section. 
     
     
       26. The cutting element of claim 21, wherein a portion of the cutting surface at the central axis is flat and transitions into the varying radius of curvature for the plurality of sections at a distance from a circumferential surface of the ultrahard layer. 
     
     
       27. A fixed cutter drill bit comprising a body, blades extending from the body, and the cutting element as recited in claim 21 mounted thereon on at least one blade. 
     
     
       28. A shear cutter type cutting element, comprising:
 a substrate; and   an ultrahard layer on an end face of the substrate, the ultrahard layer including:
 a central longitudinal axis; 
 a cylindrical peripheral side surface extending longitudinally from the substrate and defining a periphery of the ultrahard layer; and 
 a cutting surface at an upper end of the ultrahard layer, opposite the substrate, the cutting surface comprising:
 an upper surface intersecting the central longitudinal axis; and 
 a sectional surface extending between the upper surface and the cylindrical peripheral side surface, the sectional surface comprising a plurality of sections having varying radii of curvature along a plane in which the central axis lies; 
 
 wherein the sectional surface has a different geometry in different circumferential sections of the cutting face; and 
 wherein the cutting surface is free of any sharp edges in cross-section. 
   
     
     
       29. The cutter of claim 28, wherein the varying radius of curvature are selected from flat, convex, and concave. 
     
     
       30. The cutter of claim 29, wherein the varying radius of curvature include at least one convex section abutting at least one flat section, the at least one flat section abutting at least one concave section. 
     
     
       31. The cutter of claim 28, wherein the variance in the radius of curvature terminates at a point along the cutting surface a distance from a circumferential surface of the ultrahard layer. 
     
     
       32. The cutting element of claim 28, wherein a portion of the cutting surface, in cross-section, has a flat section. 
     
     
       33. The cutting element of claim 28, wherein a portion of the cutting surface at the central longitudinal axis is flat and transitions into the varying radius of curvature for the plurality of sections at a distance from the peripheral side surface of the ultrahard layer. 
     
     
       34. A fixed cutter drill bit comprising a body, blades extending from the body, and the cutting element as recited in claim 28 mounted thereon on at least one blade. 
     
     
       35. A shear cutter type cutting element, comprising:
 a substrate; and   an ultrahard layer on an end face of the substrate, the ultrahard layer including:
 a central longitudinal axis; 
 a cylindrical peripheral side surface extending longitudinally from the substrate such that the central longitudinal axis extends longitudinally at a center of the cylindrical peripheral side surface of the ultrahard layer and the substrate; and 
 a cutting surface at an upper end of the ultrahard layer, opposite the substrate and intersecting the central longitudinal axis, extending to the peripheral side surface and forming a cutting edge at its periphery, 
 wherein the cutting surface has a plurality of sections of varying radius of curvature, along a plane in which the central axis lies, 
 wherein a portion of the cutting surface at the central longitudinal axis is flat and transitions at a smoothly curved transition into the varying radius of curvature of the plurality of sections at a distance from the peripheral side surface of the ultrahard layer, 
 wherein the plurality of sections are located circumferentially around the cutting surface in spaced apart circumferential sections of the cutting surface. 
   
     
     
       36. The cutter of claim 35, wherein the varying radius of curvature are selected from flat, convex, and concave. 
     
     
       37. The cutter of claim 36, wherein the varying radius of curvature include at least one convex section abutting to at least one flat section, the at least one flat section abutting to at least one concave section. 
     
     
       38. The cutter of claim 35, wherein the variance in the radius of curvature terminates at a point along the cutting surface a distance from a circumferential surface of the ultrahard layer. 
     
     
       39. The cutting element of claim 35, where the cutting surface is free of any sharp edges in cross-section. 
     
     
       40. The cutting element of claim 35, wherein the cutting surface has more than two sections of varying radius of curvature. 
     
     
       41. A fixed cutter drill bit comprising a body, blades extending from the body, and the cutting element as recited in claim 35 mounted thereon on at least one blade. 
     
     
       42. A shear cutter type cutting element, comprising:
 a substrate; and   an ultrahard layer on an end face of the substrate, the ultrahard layer including:
 a central longitudinal axis; 
 a cylindrical peripheral side surface extending longitudinally from the substrate and defining a periphery of the ultrahard layer; and 
 a cutting surface at an upper end of the ultrahard layer, opposite the substrate, the cutting surface comprising:
 an upper surface intersecting the central longitudinal axis; and 
 a sectional surface extending between the upper surface and the peripheral side surface, the sectional surface comprising a plurality of sections of varying radius of curvature along a plane in which the central axis lies; 
 
 wherein the plurality of sections comprises two sections that are alternatingly positioned between three convex sections, wherein the two sections are flatter than the three convex sections; and 
 wherein the sectional surface has a different geometry in adjacent circumferential sections of the cutting face. 
   
     
     
       43. The cutter of claim 42, wherein the varying radius of curvature are selected from flat, convex, and concave. 
     
     
       44. The cutter of claim 42, wherein the two sections include a first flat section and a second flat section, wherein the first flat section is adjacent to and between a first and a second of the three convex sections, wherein the second flat section is adjacent to and between the second convex section and a third of the three convex sections, and wherein the first convex section, the second convex section, and the third convex section have different radii of curvatures. 
     
     
       45. The cutter of claim 42, wherein the variance in the radius of curvature terminates at a point along the cutting surface a distance from the peripheral side surface of the ultrahard layer. 
     
     
       46. The cutting element of claim 42, where the cutting surface is free of any sharp edges in cross-section. 
     
     
       47. The cutting element of claim 42 wherein the upper surface is flat and transitions at a smoothly curved transition into the sectional surface at a distance from the peripheral side surface of the ultrahard layer. 
     
     
       48. The cutting element of claim 42, wherein the cutting surface has more than two sections of varying radius of curvature. 
     
     
       49. A fixed cutter drill bit comprising a body, blades extending from the body, and the cutting element as recited in claim 42 mounted thereon on at least one blade.