Deterioration in boring efficiency is curbed and the costs of repolishing are reduced by curbing wear-width progression of a distal end portion of a tip main body of a drilling tip. A drilling tip that is attached to a distal end surface of a tool main body of a drilling tool which is rotated around an axis and in which a striking force is applied to a distal end side in a direction of the axis. The drilling tip includes a tip main body (1) in which a base end portion (2) having a columnar shape and a distal end portion (3) protruding from this base end portion (2) to the distal end side are integrally formed. The distal end portion (3) includes a curved convex surface-shaped portion (4) protruding to the distal end side of the tip main body (1), and a projection portion (5) extending in a diameter direction with respect to a center line C of the base end portion (2) viewed from the distal end side of the tip main body (1) and further protruding to the distal end side from a surface of the curved convex surface-shaped portion (4).

Deterioration in boring efficiency is curbed and the costs of repolishing are reduced by curbing wear-width progression of a distal end portion of a tip main body of a drilling tip. A drilling tip that is attached to a distal end surface of a tool main body of a drilling tool which is rotated around an axis and in which a striking force is applied to a distal end side in a direction of the axis. The drilling tip includes a tip main body (1) in which a base end portion (2) having a columnar shape and a distal end portion (3) protruding from this base end portion (2) to the distal end side are integrally formed. The distal end portion (3) includes a curved convex surface-shaped portion (4) protruding to the distal end side of the tip main body (1), and a projection portion (5) extending in a diameter direction with respect to a center line C of the base end portion (2) viewed from the distal end side of the tip main body (1) and further protruding to the distal end side from a surface of the curved convex surface-shaped portion (4).

A method of forming a composite cutter for a downhole drilling tool is described. The method includes: mixing a polycrystalline diamond powder and a cubic boron nitride powder with a molar ratio between 0.1 and 0.9 to form a catalyst-free composite mixture; placing the catalyst-free composite mixture into a mold configured in a shape of a cutter; exposing the catalyst-free composite mixture to an ultra-high-pressure, high-temperature treatment including a pressure between 11 Gigapascals (GPa) and 20 GPa, and a temperature between 1300 Kelvins (K) and 2600 K to form a solid composite body; and cooling the solid composite body to form the composite cutter.

A cutting element may include a substrate and an ultrahard layer. A top surface of the ultrahard layer includes a peripheral edge extending around the cutting element, a cutting crest extending across a major dimension of the cutting element from a cutting edge at a first portion of the peripheral edge to a modified region at a central axis of the ultrahard layer, and a lateral portion extending across a minor dimension of the cutting element from the peripheral edge to the modified region. The modified region along the major dimension includes a concave cross-sectional shape. The lateral portion along the minor dimension from the peripheral edge to the modified region includes one or more of a linear shape and a convex shape, and the modified region along the minor dimension includes a planar shape perpendicular to the central axis.

In an embodiment, a polycrystalline diamond table includes a plurality of bonded diamond grains and a plurality of interstitial regions defined by the plurality of bonded diamond grains. The polycrystalline diamond table may be at least partially leached such that at least a portion of at least one interstitial constituent has been removed from at least a portion of the plurality of interstitial regions by exposure to a leaching agent. The leaching agent may include a mixture having a ratio of weight % hydrofluoric acid to weight % nitric acid of about 1.0 to about 2.4, and water in a concentration of about 50 weight % to about 85 weight %. Various other materials, articles, and methods are also disclosed.

In an embodiment, a polycrystalline diamond table includes a plurality of bonded diamond grains and a plurality of interstitial regions defined by the plurality of bonded diamond grains. The polycrystalline diamond table may be at least partially leached such that at least a portion of at least one interstitial constituent has been removed from at least a portion of the plurality of interstitial regions by exposure to a leaching agent. The leaching agent may include a mixture having a ratio of weight % hydrofluoric acid to weight % nitric acid of about 1.0 to about 2.4, and water in a concentration of about 50 weight % to about 85 weight %. Various other materials, articles, and methods are also disclosed.

A multi-indenter drill bit includes a plurality of indenters arranged on a drilling surface of a bit face. The ratio of the total indenter area to the bit face area is defined by a parameter KPI.sub.1 (expressed as a percentage), and the ratio of the average individual indenter area to the bit face area is defined by a parameter KPI.sub.2, (expressed as a percentage). The relationship between KPI.sub.1 and KPI.sub.2 is defined by an equation.

A multi-indenter drill bit includes a plurality of indenters arranged on a drilling surface of a bit face. The ratio of the total indenter area to the bit face area is defined by a parameter KPI.sub.1 (expressed as a percentage), and the ratio of the average individual indenter area to the bit face area is defined by a parameter KPI.sub.2, (expressed as a percentage). The relationship between KPI.sub.1 and KPI.sub.2 is defined by an equation.

The invention relates to reamers used in downhole oil well drilling operations, particularly in reaming while drilling applications. Presented is a reamer having an interior channel which runs along an elongate axis of the entire body of the reamer, wherein there are openings along both ends of the reamer, exposing the interior channel. Additionally presented in the reamer are a plurality of paths extending parallel to the interior channel along the exterior of the body of the reamer, and running in a helical pattern along the entirety of the exterior of the body of the reamer. Disposed within the helical paths are a plurality of cutting inserts, which cutting inserts are enabled to provides a uniform cutting surface against a well bore, which preferably improves cutting action and reduces strain on the reamer.

Rotary drill bits may include on or more cutting element assemblies which include a cutter and a mounting system. In one embodiment, the mounting system includes a housing, a first bearing component disposed within the housing, and a second bearing component associated with the cutting element. In certain embodiments, the bearing components may comprise a table of superhard material bonded with a substrate. In one or more embodiments, the bearing components may include bearing surfaces that are arcuate. For example, the bearing surfaces may be substantially spherical (a portion of a sphere). The bearing components may be arranged to act as a radial bearing as well as a thrust bearing for the cutting element, enabling the cutting element to rotate about a longitudinal axis of the cutter, relative to the housing, while also enabling the longitudinal axis of the cutter to be displaced (change angles) relative to the housing.