Claims
- 1. A cutter comprising:
- a) a hard substrate;
- b) a cutting surface made of a hard, superabrasive material;
- wherein said substrate and said cutting surface together form an essentially cylindrical shape; wherein said cutting surface comprises a surface layer of said hard, superabrasive material on a first face of the cutter and a ridge of said hard, superabrasive material protruding from said surface layer into said substrate; wherein said ridge runs from the interior of said cutter to the perimeter of said cutter; wherein the apex of said ridge is defined as a line which runs from a first point in the interior of said cylinder on the interface between said substrate and said surface layer to a second point on the perimeter of said cutter at a distance from said interface; wherein the cross-section of said ridge approximates the shape of the wear scar which will form on said cutter; and wherein said line forms an angle .phi. with the longitudinal axis of the cutter.
- 2. A cutter in accordance with claim 1 wherein said apex of said ridge is defined by a line.
- 3. A cutter in accordance with claim 1 wherein said apex of said ridge has a U-shaped cross section.
- 4. A cutter in accordance with claim 1 wherein said apex of said ridge has an elliptical cross section.
- 5. A cutter in accordance with claim 1 wherein said ridge has a parabolic cross section.
- 6. A cutter in accordance with claim 1 wherein said hard, superabrasive material is selected from the group consisting of cubic boron nitride and polycrystalline diamond; and wherein said substrate material is selected from the group consisting of tungsten carbide, boron tetracarbide, tantalum carbide, vanadium carbide, niobium carbide, halfnium carbide, and zirconium carbide.
- 7. A cutter in accordance with claim 6 wherein said hard, superabrasive material is polycrystalline diamond.
- 8. A cutter in accordance with claim 6 wherein said substrate material is tungsten carbide.
- 9. A cutter in accordance with claim 1 wherein .phi. is selected so that said second point is in the central region of said cutter.
- 10. A cutter in accordance with claim 1 wherein .phi. is selected so that said second point extends beyond said central longitudinal axis of the cutter.
- 11. A cutter in accordance with claim 1 wherein the interface between said substrate and said cutting surface is curved in the region where said ridge intersects said surface layer to avoid the formation of stress risers.
- 12. A cutter in accordance with claim 1 wherein the interface between said substrate and said surface layer is ridged to improve transfer of stresses between said substrate and said surface layer.
- 13. A cutter in accordance with claim 1 wherein the interface between said substrate and said surface layer has been chemically etched to improve transfer of stresses between said substrate and said surface layer.
- 14. A cutter in accordance with claim 1 wherein .phi. is between 10 and 80 degrees.
- 15. A cutter in accordance with claim 1 wherein .phi. is between 20 and 70 degrees.
- 16. A cutter in accordance with claim 1 wherein .phi. is between 30 and 60 degrees.
- 17. An apparatus for use in drilling subterranean formations, comprising a body presenting an exterior surface having at least one cutting element secured thereto, said at least one cutting element comprising:
- (a) a hard substrate;
- (b) a cutting surface made of a hard, superabrasive material; and
- (c) an interface between said hard substrate and said cutting surface;
- wherein said substrate and said cutting surface together form an essentially cylindrical shape; wherein said cutting surface comprises a surface layer of said hard, superabrasive material on a first face of the cutting element, said cutting element having an interior, a perimeter and a longitudinal axis, and a ridge of said hard, superabrasive material protruding from said surface layer into said substrate; wherein said ridge has an apex and a cross section and wherein said ridge runs from said interior of said cutting element to said perimeter of said cutting element; wherein said apex of said ridge is defined by a line which runs from a first point in said interior of the cutting element on said interface between said substrate and said surface layer to a second point on said perimeter of said cutting element at a distance from said interface; wherein said cross-section of said ridge has a shape approximating a shape of a wear scar which will form on said cutting element; and wherein said line forms an angle .phi. with said longitudinal axis of the cutting element.
- 18. A method of manufacturing a cutter in accordance with claim 1, comprising the steps of:
- a) placing a disk-shaped cemented carbide substrate into a cartridge;
- b) loading a layer of diamond crystals into said cartridge adjacent one face of the substrate;
- c) loading said cartridge into an ultra-high pressure press; and
- d) compressing said substrate and adjacent diamond crystal layer under ultra-high temperature and pressure conditions such that a diamond table is formed over the substrate face, said diamond table also being bonded to said one face of said substrate;
- wherein said cemented carbide substrate has a trough-like indentation extending from its central region to its perimeter; and wherein said trough-like indentation is deeper at said perimeter than at said central region.
Parent Case Info
This application claims the benefit of U.S. Provisional Application Ser. No. 60/018,263, filed on May 24, 1996.
US Referenced Citations (47)
Foreign Referenced Citations (1)
Number |
Date |
Country |
2 240 797 |
Aug 1991 |
GBX |