Abstract: A bit body formed of a mixture of matrix material and superabrasive powder and including pockets lined with superabrasive-free matrix material, and a method for forming the same, are provided. The pockets are shaped to receive cutting elements therein. The superabrasive-free matrix material enhances braze strength when a cutting element is brazed to surfaces of the pocket. The method for forming the drill bit body includes providing a mold and displacements. The displacements are coated with a mixture of superabrasive free matrix-material and an organic binder. The mold is packed with a mixture of matrix material and superabrasive powder and the arrangement heated to form a solid drill bit body. When the solid bit body is removed from the mold, pockets are formed by the displacements in the bit body and are lined with the layer of superabrasive-free matrix material. The superabrasive material may be diamond, polycrystalline cubic boron nitride, SiC or TiB2 in exemplary embodiments.

Abstract: A drill bit including a bit body and an upper portion, wherein the bit body and the upper portion are comprised of a matrix material, and wherein the upper portion includes a threaded connection comprised of a machineable matrix material is disclosed.

Abstract: An insert for a drill bit which includes a diamond impregnated body, and a shearing portion disposed on said body is shown. In addition, a method for forming a drill bit that includes (a) forming a shearing portion on a diamond-impregnated insert body to form a cutting insert, (b) forming a bit body having a plurality of sockets sized to receive a plurality of the cutting inserts, and (c) mounting the plurality of cutting inserts in the bit body and affixing the plurality of cutting inserts to the bit body; wherein steps (a)-(c) are carried out such that a total exposure of the diamond-impregnated insert to temperatures above 1000° F. is greater than a total exposure of the shearing portion to temperatures above 1000° F.

Abstract: An insert for a drill bit which includes a diamond impregnated body, and a shearing portion disposed on said body is shown. In addition, a method for forming a drill bit that includes (a) forming a shearing portion on a diamond-impregnated insert body to form a cutting insert, (b) forming a bit body having a plurality of sockets sized to receive a plurality of the cutting inserts, and (c) mounting the plurality of cutting inserts in the bit body and affixing the plurality of cutting inserts to the bit body; wherein steps (a)–(c) are carried out such that a total exposure of the diamond-impregnated insert to temperatures above 1000° F. is greater than a total exposure of the shearing portion to temperatures above 1000° F.

Abstract: This invention provides an improved cutting element for downhole cutting tools including a support element and a beveled shearing element disposed on the support element and a drill bit including the cutting element; a cutting element including a support element and a shearing element disposed on the support element, wherein the shearing element includes TSP, a sharpened cutting edge, and at least one blended edge that forms part of an interface with the support element and a drill bit including the cutting element. Cutting inserts including an insert body and the shearing elements disclosed above are provided. Also provided are methods for forming the cutting elements and drill bit inserts and a method for drilling mixed earth formations using the improved downhole cutting tools of the present invention.

Abstract: An insert for a drill bit which includes a diamond impregnated body, and a shearing portion disposed on said body is shown. In addition, a method for forming a drill bit that includes (a) forming a shearing portion on a diamond-impregnated insert body to form a cutting insert, (b) forming a bit body having a plurality of sockets sized to receive a plurality of the cutting inserts, and (c) mounting the plurality of cutting inserts in the bit body and affixing the plurality of cutting inserts to the bit body; wherein steps (a)-(c) are carried out such that a total exposure of the diamond-impregnated insert to temperatures above 1000° F. is greater than a total exposure of the shearing portion to temperatures above 1000° F.