Abstract: A method is disclosed comprising the steps of locating, on a surface of a downhole component, a plurality of thermally stable polycrystalline diamond (TSP) bearing elements, and then applying to the surface a settable facing material which bonds to the surface between the bearing elements and embraces the elements to hold them in place. A method in which bearing elements each comprising a body of TSP at least partly surrounded by a layer of less hard material are secured to the surface by welding or brazing part of the surface of each bearing element which comprises said less hard material to said component is also described.

Abstract: A rotary drill bit is manufactured by a method including the step of forming at least a portion of the bit body from a precipitation hardening alloy, and brazing cutters to the bit body by a heating and cooling cycle during which the bit body is first heated to a temperature sufficient to melt the brazing material and is then cooled to room temperature, the heating and cooling brazing cycle being controlled in a manner so as also to effect precipitation hardening of the alloy from which the bit body is formed. In the case where the bit body is formed from solid infiltrated matrix material around a solid preformed mandrel, the heating and cooling cycle of the matrix forming process may also be controlled in a manner to effect precipitation hardening of the alloy from which the mandrel is formed.

Abstract: A method is disclosed comprising the steps of locating, on a surface of a downhole component, a plurality of thermally stable polycrystalline diamond (TSP) bearing elements, and then applying to the surface a settable facing material which bonds to the surface between the bearing elements and embraces the elements to hold them in place. A method in which bearing elements each comprising a body of TSP at least partly surrounded by a layer of less hard material are secured to the surface by welding or brazing part of the surface of each bearing element which comprises said less hard material to said component is also described.

Abstract: A method of applying a wear-resistant material to a surface of a downhole component for use in subsurface drilling comprises forming a plurality of bearing elements, applying a layer of an electrically conductive, less hard material to each bearing element, and then bonding each bearing element to the surface of the component by welding or brazing to the surface of the component a part of the surface of the bearing element which comprises said less hard material, wherein the layer is of thickness greater than 0.05mm.

Abstract: A method is disclosed comprising the steps of locating, on a surface of a downhole component, a plurality of thermally stable polycrystalline diamond (TSP) bearing elements, and then applying to the surface a settable facing material which bonds to the surface between the bearing elements and embraces the elements to hold them in place. A method in which bearing elements each comprising a body of TSP at least partly surrounded by a layer of less hard material are secured to the surface by welding or brazing part of the surface of each bearing element which comprises said less hard material to said component is also described.

Abstract: A rotary drill bit is manufactured by a powder metallurgy process by placing a metal mandrel in a mold, packing the mold with particulate matrix-forming material, infiltrating the material with a molten binding alloy, and cooling the assembly to form a solid infiltrated matrix bonded to the mandrel. The mandrel comprises an outer part surrounded by the matrix-forming material and an inner part, secured to the outer part but out of contact with the matrix-forming material. The outer part of the mandrel is formed from a material having thermal characteristics close to those of the matrix, so as to reduce the tendency for the matrix to crack under thermal stress, while the inner part of the mandrel is formed from a precipitation-hardening material, the strength and hardness of which increases in the infiltration process and the subsequent heating/cooling cycle for brazing the cutters on to the drill bit.

Abstract: A rotary drill bit is manufactured by a method including the step of forming at least a portion of the bit body from a precipitation hardening alloy, and brazing cutters to the bit body by a heating and cooling cycle during which the bit body is first heated to a temperature sufficient to melt the brazing material and is then cooled to room temperature, the heating and cooling brazing cycle being controlled in a manner so as also to effect precipitation hardening of the alloy from which the bit body is formed. In the case where the bit body is formed from solid infiltrated matrix material around a solid preformed mandrel, the heating and cooling cycle of the matrix forming process may also be controlled in a manner to effect precipitation hardening of the alloy from which the mandrel is formed.