A cutting tool includes: a main body portion composed of a cemented carbide; and a front end portion composed of a binderless cubic boron nitride polycrystal, the front end portion being joined to the main body portion. In an axial direction along a rotation axis of the main body portion, the main body portion has a first end and a second end opposite to the first end. The front end portion has a neck portion and an edge portion, the neck portion protruding from the second end along the axial direction, the edge portion being continuous to the neck portion, the edge portion being located at a location distant away from the second end relative to the neck portion in the axial direction. In the axial direction, the neck portion has a third end on the edge portion side and a fourth end opposite to the third end.

A method for machining ribs or grooves on a workpiece such as a shaft or an air or gas axial bearing intended to be rotated about a longitudinal axis of a centrifugal compressor. All of the ribs or grooves are obtained at once by the machining tool on a workpiece portion driven such that it rotates, by moving the workpiece or the tool holder in a longitudinal machining direction, the machining tool moving back and forth with a machining position in contact with the workpiece and a position wherein it is not in contact with the workpiece from the start to the end of the workpiece portion. The back-and-forth movements of the machining tool are synchronised with the sinusoidal program set up in the machining unit, as well as with the desired, programmed arrangement of the ribs or grooves to be produced on the workpiece portion.

A method for producing a drill ring for a core drill bit is disclosed. The method includes constructing at least two green parts from encapsulated diamond particles, the diamond particles being covered by a powder mixture. The green parts are formed into ring segments under the effect of pressure and the ring segments are annularly assembled and sintered under temperature action to form a continuous drill ring.

A diamond sintered material includes diamond grains, wherein a content ratio of the diamond grains is more than or equal to 80 volume % and less than or equal to 99 volume % with respect to the diamond sintered material, an average grain size of the diamond grains is more than or equal to 0.1 μm and less than or equal to 50 μm, and a dislocation density of the diamond grains is more than or equal to 1.2×10.sup.16 m.sup.−2 and less than or equal to 5.4×10.sup.19 m.sup.−2.

A coated tool, such as a rotating, cutting tool, includes a tool body and a multilayer wear protection coating system. The wear protection system coats a functional surface of the tool body that is subject to wear and includes a first undoped diamond layer and a second undoped diamond layer disposed over the first undoped diamond layer. The first undoped diamond layer is electrically conductive and exhibits grain boundary conductivity from delocalized electrons. The second undoped diamond layer is electrically insulating. The first undoped diamond layer is 4-20 microns thick and is made with diamond grains whose size ranges from 4-10 nm. The first and second diamond layers are applied by chemical vapor deposition (CVD) using a hot-wire method. The wear protection system also includes an additional undoped diamond layer that is electrically insulating and is disposed between the functional surface of the tool body and the first diamond layer.

The present invention provides a cutting tool which has a flat top face but still has excellent chip control. The cutting tool includes: a peripheral side face; a top face which is a flat top face constituting a part of an upper surface that is depressed except for the portion of the top face; a cutting edge that is formed at least on a ridge line of a corner R connecting two linear ridge lines, out of ridge lines where the peripheral side face and top face cross; and a fan-shaped rake portion including ridge portions and groove portions, which are disposed alternately and are both depressed so as to be inclined from the corner R, where the crossing line with the top face appears in a wave form, toward a pivot portion which is a center of radial portions.

A high-pressure high-temperature, HPHT, diamond tool piece and a method of producing an HPHT diamond tool piece. At least a portion of the HPHT diamond tool piece comprises an aggregated nitrogen centre to C-nitrogen centre ratio of greater than 30%. The method includes irradiating an HPHT diamond material to introduce vacancies in the diamond crystal lattice, annealing the HPHT diamond material such that at least a portion of the HPHT diamond material comprises an aggregated nitrogen centre to C-nitrogen centre ratio of greater than 30%, and processing the HPHT diamond material to form an HPHT diamond tool piece.

A rotation mechanism 9 rotates a spindle 2a to which a workpiece 6 is attached. A feed mechanism 8 feeds a cutting edge 4a positioned obliquely relative to a rotation axis of the workpiece 6 in a direction containing a cutting direction component orthogonal to the rotation axis with the cutting edge 4a cutting into the workpiece 6 to machine a surface of the workpiece 6. The cutting edge 4a of a cutting tool 4 has been formed by scanning a cylindrical irradiation region including a focused spot of laser light over a diamond-coated layer of a chip base material.

One example of the present disclosure relates to a coupon. The coupon includes a first surface with a first circular channel and a second surface opposite and parallel to the first surface. The second surface is spaced a distance D0 from the first surface and includes a second circular channel concentric with the first circular channel. The coupon also includes a toroidal portion between the first circular channel and the second circular channel. The toroidal portion includes a rectangular sectional portion.

A method for manufacturing a cutting tool having a rake face, a flank face, and an edge having a ridge line interconnecting the rake face and the flank face, wherein on the flank face there is a cutting edge region from the ridge line of the edge to a point A away therefrom on the side of the flank face by a distance X, the method comprising producing and processing the flank face with a laser, the producing and processing being producing and processing the cutting edge region along the ridge line of the edge with a first laser beam having a depth of focus equal to or deeper than a width of the cutting edge region when the distance X is the width of the cutting edge region, the distance X being 0.2 mm or more and 5 mm or less.