Conical cutters for drill bits, and processes to produce same

Claim 1

A roller bit cutter, comprising, in combination: (a) a tough, metallic generally conical and fracture resistant core having a hollow interior, the core defining an axis, (b) an annular metallic radial bearing layer carried by said core at the interior thereof to support the core for rotation, said bearing layer extending about said axis, (c) an impact and wear resistant metallic inner layer on the core, at the interior thereof, to provide an axial thrust bearing, and (d) hard metallic inserts having anchor portions carried by the core and partly embedded therein the inserts protruding outwardly at the exterior of the core to define cutters, at least some of the inserts spaced about said axis, (e) and a wear resistant outer metallic layer on the exterior of said core, (f) said core defining multiple recesses reciving said insert anchor portions, said outer metallic layer extending into said recesses and between the core and said insert anchor portions, (g) said outer layer consolidated under pressure in situ to look to and about the anchor portions of the inserts in said recesses, the insert anchor portions tapered in directions extending toward the exterior of the recesses, and the outer layer engaging said tapered anchor portions to have taper corresponding to that of said insert anchor portions, (h) said core consisting of consolidated ferrous powder metal steel having the following composition, with percentages being by weight: ______________________________________ iron 79 to 98% copper 0 to 20% carbon 0.4 to 1.0% nickel 0 to 4.0% ______________________________________ (i) said outer layer consisting of a composite mixture of refractory particles in a binder metal.

Claim 17

The method of producing a roller bit cutter, that includes the steps: (a) providing a tough, metallic generally conical and fracture resistant core having a hollow interior, the core defining an axis, (b) providing an annular metallic radial bearing layer carried by said core at the interior thereof to support the core for rotation, said bearing layer extending about said axis, (c) providing an impact and wear resistant metallic inner layer on the core, at the interior thereof, to provide an axial thrust bearing, (d) providing hard metallic inserts having anchor portion carried by the core and partly embedded therein, the inserts protruding outwardly at the exterior of the core to define cutters, at least some of the inserts spaced about said axis, (e) providing a wear resistant outer metallic layer on the exterior of said core, (f) providing said core with multiple recesses to receive said outer metallic layer and to receive said insert anchor portions of be surrounded by said metallic layer in said recesses, (g) said outer layer consisting of a composite mixture of refractory particles in a binder metal, and including the step of consolidating said outer layer under pressure to lock to said anchor portions, said pressure transmitted to the inserts and to the outer layer, (h) said core consisting of consolidated ferrous powder metal steel having the following composition, with percentages being by weight: ______________________________________ iron 79 to 98% copper 0 to 20% carbon 0.4 to 1.0% nickel 0 to 4.0%. ______________________________________

Claim 18

The method of producing a roller bit cutter, that includes the steps: (a) providing a tough, metallic generally conical and fracture resistant core having a hollow interior, the core defining an axis, (b) providing an annular metallic radial bearing layer carried by said core at the interior thereof to support the core for rotation, said bearing layer extending about said axis, (c) providing an impact and wear resistant metallic inner layer on the core, at the interior thereof, to provide an axial thrust bearing, (d) providing hard metallic inserts having anchor portion carried by the core and partly embedded therein, the inserts protruding outwardly at the exterior of the core to define cutters, at least some of the inserts spaced about said axis, (e) providing a wear resistant outer metallic layer on the exterior of said core, (f) providing said core with multiple recesses to receive said outer metallic layer and to receive said insert anchor portions of be surrounded by said metallic layer in said recesses, (g) said outer layer consisting of a composite mixture of refractory particles in a binder metal, and including the step of consolidating said outer layer under pressure to lock to said anchor portions, said pressure transmitted to the inserts and to the outer layer, (h) said core consisting of consolidated ferrous powder metal steel having the following composition, with percentages being by weight: ______________________________________ iron 79 to 98% copper 0 to 20% carbon 0.4 to 1.0% nickel 0 to 4.0%. ______________________________________

Claim 21

The method of one of claims 16-18 wherein at least one of said layers consists essentially of consolidated powder metal.

Claim 22

The method of one of claims 16-18 wherein at least two of said layers consist of consolidated powder metal, and said pressure is transmitted to both layers.

Claim 23

The method of one of claims 16-18 wherein said bearing layer and inner layer consist of consolidated powder metal, and said pressure is transmitted to all three layers.

Claim 25

The method of claims 18 or 22 wherein the core has mechanical properties in excess of the following lower limits: 130 ksi ultimate tensile strength 80 ksi yield strength 5% tensile elongation 15% reduction in area 10 ft-lb (izod) impact strenth.