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US 5,443,337 AGranted
Sintered diamond drill bits and method of making
OwnerIchiro Katayamainventor
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OwnerIchiro Katayamainventor
Estimating the term…
A drill bit for cutting hard and abrasive materials has cutting lips formed from sintered polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN) contained in one or more inserts installed in a drill bit blank. The inserts are made by forming depressions in the upper surface of a matrix slab of tungsten carbide, filling the depressions with fine mesh grains of diamonds or cubic born nitride, subjecting the slab to heat and pressure sufficient to fuse the grains to one another and to the surrounding matrix walls, and then cutting the matrix slab to remove individual inserts containing an elongated vein having an exposed PCD or PCBN surface supported by at least one and preferably two or more side walls of tungsten carbide. A rectangular slot having side walls parallel to one another and equidistant from the diameter of a cylindrical drill bit blank is cut into one transverse end wall of the blank, and one or more inserts placed in the slot. The tungsten carbide walls of the inserts are then brazed to the adjacent side walls of the slot. The bit is then ground to a desired configuration, in which PCD or PCBN material forms at least part of at least one cutting lip of the finished drill bit. Preferably, flutes are formed in drill bit blank as part of the grinding operation.
An improved drill bit of the type having an elongated cylindrical body, a pair of helical flutes formed in said body, each of said flutes having an outer edge surface in the form of a strip-shaped margin, a central longitudinally disposed web section between said flutes, and a cutting point having a conical shape intersecting each said margin and forming therewith a cutting lip having the shape of a knife edge disposed between the apex of said point and each one of a pair of diametrically opposed margins, each of said cutting lips being located on diametrically opposite sides of said web and spaced laterally apart from the longitudinal center plane of said web, said improvement comprising;
An improved drill bit of the type having an elongated cylindrical body, a pair of helical flutes along the sides of said body, the outer edge surface of each flute having a strip-shaped margin, a central longitudinally disposed web section between said flutes and a cutting point having a conical surface intersecting each margin and forming therewith a cutting lip having the shape of a knife edge disposed between the apex of the tip and each one of a pair of diametrically opposed said margins, each of said cutting lips being located on a diametrically opposed side of said web and spaced laterally apart from the longitudinal center plane of said web, said improvement comprising at least one first type insert secured in a slot formed in said web and extending inward into said body from said point, said insert comprising an elongated, straight block of refractory material fused by heat and pressure into an elongated, straight channel formed in one surface of a matrix, said block of refractory material comprising grains of a material harder than the material of which said matrix is made, at least a portion of said refractory material being coextensive with at least a portion of one of said cutting lips.
Dependencies are inferred from the claim text.