Tungsten Carbide Bit with Hardfaced Nose Area

Abstract

An earth-boring bit has rotatable cones with rows of carbide elements installed thereon. A nose is symmetrically arranged on a cone axis of one of the cones. The nose has a central core that protrudes outward. A base joins supporting metal of the cone. A free end is opposite the base. Teeth are formed on the cone between the base and the free end, the teeth extending radially outward. A hard facing layer is located on the teeth. Intermediate hardfacings extend outward from the core between each of the teeth. The intermediate hardfacings may be lugs and preferably extend the same distance from the core as the teeth.

1 . An earth boring bit, comprising:
 a plurality of rotatable cones;   rows of carbide cutting elements installed within mating holes in each of the cones;   a nose on a cone axis of one of the cones, the nose having a central core with a base joining supporting metal of the cone and a free end opposite the base;   a plurality of teeth extending radially outward from the core between the base and the free end;   a hard facing layer located on the teeth; and   intermediate hardfacings extending outward from the core between each of the teeth, at least some of the intermediate hardfacings extending substantially a same distance from the core as the teeth.   
     
     
         2 . The bit according to  claim 1 , wherein each of the intermediate hardfacings comprises a lug, the lugs having leading and trailing sides spaced from the teeth. 
     
     
         3 . The bit according to  claim 1 , wherein each of the intermediate hardfacings comprises a lug having a generally triangular shape with an outermost portion of each of the intermediate hardfacings defining an apex of the triangular shape. 
     
     
         4 . The bit according to  claim 1 , wherein:
 each of the teeth has a leading side, a trailing side and a thickness extending between the leading and trailing sides; and   each of the intermediate hardfacings comprises a lug having a leading side, a trailing side, and a thickness between the leading and trailing sides of each of the lugs that is less than the thickness of each of the teeth.   
     
     
         5 . The bit according to  claim 1 , wherein:
 each of the teeth has a generally triangular shape with an apex defining an outermost portion;   a recess is located in underlying supporting material of each of the teeth; and   the hardfacing layer fills the recess and defines the apex.   
     
     
         6 . The bit according to  claim 1 , wherein the intermediate hardfacings fill each space between the teeth, defining a substantially uniform exterior side surface of the nose. 
     
     
         7 . The bit according to  claim 6 , wherein the exterior side surface comprises:
 a first frusto-conical surface extending from the free end toward the base and increasing in diameter; and   a second frusto-conical surface extending from the base toward the lower frusto-conical surface and increasing in diameter.   
     
     
         8 . The bit according to  claim 1 , wherein the teeth are integrally formed with and the same material as the core. 
     
     
         9 . The bit according to  claim 1 , wherein the core is the same material as and is integrally formed with the supporting metal of the cone. 
     
     
         10 . An earth boring bit, comprising:
 a plurality of rotatable cones;   rows of carbide cutting elements installed within mating holes in each of the cones;   a nose formed on a cone axis of one of the cones;   the nose having a plurality of teeth extending radially outward relative to a cone axis;   a hardfacing layer located on the teeth;   a lug located between each of the teeth and extending radially outward; and   each of the lugs is formed entirely of a hardfacing material containing carbide particles.   
     
     
         11 . The bit according to  claim 10 , wherein the hardfacing material of the lugs has substantially the same composition as the hardfacing layer. 
     
     
         12 . The bit according to  claim 10 , wherein each of the teeth is formed of an underlying support metal over which the hardfacing layer is applied. 
     
     
         13 . The bit according to  claim 10 , wherein each of the lugs has leading and trailing sides spaced from the teeth. 
     
     
         14 . The bit according to  claim 10 , wherein each of the lugs has a generally triangular shape with an outermost portion of each of the lugs defining an apex of the triangular shape. 
     
     
         15 . The bit according to  claim 10 , wherein:
 each of the teeth has a leading side, a trailing side and a thickness extending between the leading and trailing sides; and   each of the lugs has a leading side, a trailing side, and a thickness between the leading and trailing sides of each of the lugs that is less than the thickness of each of the teeth.   
     
     
         16 . The bit according to  claim 10 , wherein:
 each of the teeth has a generally triangular shape with an apex defining an outermost portion;   a recess is located in underlying supporting material of each of the teeth at the apex; and   the hardfacing layer fills the recess and defines the apex.   
     
     
         17 . An earth boring bit, comprising:
 a plurality of rotatable cones, each of the cones having a metal shell;   rows of carbide cutting elements installed within mating holes in the shell of each of the cones;   a nose arranged on a cone axis of one of the cones, the nose having a central core formed of underlying support metal that is the same as the metal of the shell, the core having a base joining the shell and a free end opposite the base;   a plurality of teeth extending radially outward from the core between the base and the free end relative to a cone axis, the teeth being formed of the same metal as the metal of the core and the shell;   a hard facing layer located on each of the teeth, defining a generally triangular shape for each of the teeth with an apex of the triangular shape being located between the base and the free end, the hardfacing layer defining leading and trailing sides for each of the teeth and being formed of carbide particles within a matrix metal;   a lug extending outward from the core between each of the teeth substantially a same distance from the core as the apex of each of the teeth, each of the lugs having leading and trailing sides spaced from leading and trailing sides of adjacent ones of the teeth;   each of the lugs having a generally triangular shape with an apex defining a radially outermost portion of each of the lugs; and   each of the lugs being formed entirely of a hardfacing material containing carbide particles within a matrix metal.   
     
     
         18 . The bit according to  claim 17 , wherein:
 a thickness between the leading and trailing sides of each of the lugs is less than a thickness of each of the teeth.   
     
     
         19 . The bit according to  claim 17 , wherein:
 the portion of the core to which each of the lugs joins tapers in an outward direction toward the base.   
     
     
         20 . The bit according to  claim 17 , wherein each of the lugs has a first end spaced from the free end of the core and a second end spaced from the base.