A cemented carbide may include a hard phase that may include W and C, a first solid solution phase and a second solid solution phase, each of which may include W, C, Ti and Zr, and a binder phase that may include an iron group metal. The cemented carbide may include 1.0-3.0 mass % of the Ti in terms of TiC, and 0.75-2.0 mass % of the Zr in terms of ZrC. An amount of the Ti in terms of TiC may be more than 1 time and less than three times an amount of the Zr in terms of ZrC. The first solid solution phase may satisfy a relationship of 0.1Ti/(Ti+Zr)<0.4 in terms of atomic ratio. The second solid solution phase satisfies a relationship of 0.7Ti/(Ti+Zr)0.9 in terms of atomic ratio.

A cutting tool body includes a first member and a second member, both having a substantially cylindrical shape, and arranged such that a tool body central axis coincides with a central axis of each of the first and the second members. The first member has a tool characteristic of a first magnitude and the second member has the tool characteristic of a second magnitude, different from the first magnitude. The cutting tool body includes a transition member arranged between the first and second members and connected at a first end to the first member and at a second end to the second member. The tool characteristic in the transition member is of the first magnitude at the first end and of the second magnitude at the second end. The transition member has a transition region between the first and the second ends in which the tool characteristic transforms from the first magnitude to the second magnitude.

A surface coated cutting tool comprises a base material and a coating layer that coats the base material, the coating layer including an alternate layer composed of a first unit layer and a second unit layer alternately stacked, the first unit layer being composed of a nitride containing aluminum and zirconium, in the first unit layer, when the total number of metal atoms constituting the first unit layer is represented as 1, a ratio thereto of the number of atoms of the zirconium being not less than 0.65 and not more than 0.95, the second unit layer being composed of a nitride containing titanium and silicon, in the second unit layer, when the total number of metal atoms constituting the second unit layer is represented as 1, a ratio thereto of the number of atoms of the silicon being larger than 0 and not more than 0.20.

A surface-coated cutting tool includes a base material and a coating covering the base material. The base material includes a rake face and a flank face. The coating includes a TiCN layer. The TiCN layer has a (422) orientation in a region d1 in the rake face. The TiCN layer has a (311) orientation in a region d2 in the flank face.

A method of manufacturing clamping jaws for drill chucks, in which a pin is provided made from a blank, on which are formed a row of teeth furnished for engaging in a thread associated with the drill chuck and, axially offset on the side of the pin opposite the row of teeth, a clamping surface extending at an angle to the axis of the pin; in which at least one of the steps of quenching, carburizing, nitriding, and annealing is carried out to improve the material properties of the pin; and in which additional hardening is subsequently carried out in at least one region of the clamping jaws. The invention also relates to a clamping jaw and to a drill chuck having such clamping jaws.

A coated cutting tool comprising a cemented carbide and a coating layer formed on a surface of the cemented carbide, wherein: an average thickness of the coating layer is from 5.0 m or more to 30.0 m or less; and in the cemented carbide, when regarding a region thereof which ranges from the surface of the cemented carbide to a depth of 20.0 m in a direction opposite to the coating layer as a surface region, and also regarding a region thereof on a side opposite to the coating layer across the surface region as an inner region, an average value of KAM values in the surface region KAM.sub.s and an average value of KAM values in the inner region KAM.sub.i satisfy a condition represented by formula (1) below.
0.00|KAM.sub.sKAM.sub.i|0.10(1)

Provided is a ceramic sintered body having high wear resistance and chipping resistance. Also provided are an insert, a cutting tool and a friction stir welding tool, each of which uses such a high-performance ceramic sintered body. The ceramic sintered body includes Al.sub.2O.sub.3 (alumina), WC (tungsten carbide) and ZrO.sub.2 (zirconia), wherein Zr (zirconium) element is present at either one or both of: (1) a grain boundary between crystal grains of the Al.sub.2O.sub.3; and (2) a grain boundary of crystal grains of the Al.sub.2O and crystal grains of the WC, wherein the ceramic sintered body contains 55.0 to 97.5 vol % of the WC, 0.1 to 18.0 vol % of the ZrO.sub.2, and the balance being the Al.sub.2O.sub.3, and wherein the ZrO.sub.2 is in a phase of tetragonal structure (T) or a mixed phase of tetragonal structure (T) and monoclinic structure (M).

A cutting insert according to one embodiment includes: a rake face; a flank face continuous to the rake face; and a cutting edge constituted of a ridgeline between the rake face and the flank face. A coolant flow path is provided inside the cutting insert. One end portion of the coolant flow path opens in the flank face to form a coolant ejection hole. The flank face is provided with a coolant guide groove extending from the coolant ejection hole toward the cutting edge with a base end portion of the coolant guide groove being connected to the coolant ejection hole and with a front end portion of the coolant guide groove being disposed at a position close to the cutting edge relative to the base end portion.

A drill bit for chiseling stone includes an impact face at an insertion end of the drill bit, a hollow shank, where a delivery passage is defined within the hollow shank, and a drill head, where the drill head has, at a front end of the drill head, a cutting edge, an intake opening, and an intake passage. The intake passage connects the intake opening to the delivery passage. A cross section of the intake passage increases from the intake opening to the delivery passage.

Disclosed is a hole cutter capable of reducing a cutting load applied to a carbide tip during hole machining and improving cutting efficiency and workability. The hole cutter includes a cylindrical body, and a plurality of carbide tips disposed along an edge of the body. The carbide tips include a first carbide tip, a second carbide tip, and a third carbide tip. Assuming a circle which has a center coinciding with the body center and is in contact with a sharp tip of an upper surface portion of the first carbide tip, the second carbide tip is formed so that the sharp tip of an upper surface portion thereof is positioned at an inner region of the circle, and the third carbide tip is formed so that the sharp tip of an upper surface portion thereof is positioned at an outer region of the circle.