The current invention proposes sharpening thin hardened metal blades with the hard turning process using a holder designed to hold the blades in a firm and stiff manner and a ceramic cutting tool held in a fixture. Generally, the cutting tool is held stationary in its fixture while the workpiece, in its holder, is rotated such that it repeatedly comes into controlled contact with the cutting tool. In sharpening operations such as proposed here, it is critical to (i) hold the workpiece firmly and rigidly, and (ii) position the cutting tool in a precise, predictable and reliable manner.

An end mill includes a major-diameter shank, a cone-shaped connector portion disposed at the end of the shank, a minor-diameter body disposed by way of the connector portion coaxially therewith, a toothed element disposed at the leading end of the body, an installation recess dented slightly in the toothed element, and a cutting edge held in the installation recess so as to swell in the shape of an arc to protrude from an outer peripheral face of the body.

A second distance is longer than a first distance and a value obtained by dividing the third distance by the fourth distance is more than or equal to 0.5 and less than or equal to 0.8 when it is assumed that the first distance represents a distance between the cutting edge and the mounting surface in a direction perpendicular to the rake face, the second distance represents a distance between the mounting surface and a boundary portion between the rising portion and the flat portion in the direction perpendicular to the rake face, the third distance represents a distance between the boundary portion and a tip of the cutting edge in a direction parallel to the rake face, and the fourth distance represents a distance between the second discharging opening portion and the tip of the cutting edge in the direction parallel to the rake face.

Provided is a milling cutter including: a tool body to rotate about an axis; and cutting edges at an outer peripheral part of a front end of the tool body, wherein the cutting edges include a flat face machining cutting edge extending along a virtual plane perpendicular to the axis, and a recessed groove machining cutting edge projecting further toward a front end side in the axial direction than the flat face machining cutting edge, and the recessed groove machining cutting edge has a first inclined portion extending toward the front end side in the axial direction toward an outside in a radial direction, a second inclined portion arranged outside the first inclined portion in the radial direction and extending toward a base end side in the axial direction toward the outside in the radial direction, and a tip portion connecting the first and second inclined portions.

An end mill includes an end mill body having a bar-shape extending along a rotation axis and including a first end and a second end, a side surface, a first end cutting edge, a second end cutting edge, a first peripheral cutting edge extending from the first end cutting edge, and a second peripheral cutting edge extending from the second end cutting edge. In which, L2 is smaller than L1, where L1 is a distance from the rotation axis to the first peripheral cutting edge, and L2 is a distance from the rotation axis to the second peripheral cutting edge in a cross section orthogonal to the rotation axis. And 2 is greater than 1, where 1 is a rake angle of the first peripheral cutting edge, and 2 is a rake angle of the second peripheral cutting edge.

An object of the present invention is to provide helically fluted end mill with a diamond cutting surface. More particularly, it is an object of the present invention to provide a helically fluted end mill with helical grooves in the flutes that are filled with compacted polycrystalline diamond that can provide an effective cutting length based on the appropriate relationship between cutting length, diameter, the number of flutes, angle, and the number of polycrystalline diamond segments per flute.

A cutting tool according to an aspect of the present disclosure includes a shank, a joint, and a cutting portion attached through the joint to the shank. The cutting portion includes a core and a surface portion. The surface portion is disposed around a central axis of the cutting portion to cover an outer circumferential surface of the core. The surface portion includes a cutting edge. The cutting edge is disposed on an outer circumferential surface of the surface portion and formed in a helical shape about the central axis. The surface portion is a composite sintered material including a hard phase formed of a plurality of diamond particles and a plurality of cubic boron nitride particles, and a binder phase forming the remainder.

A rotary cutting blade material has an attaching structure forming portion that is to serve as an attaching portion to the shank, a cutting structure forming portion that is to serve as a cutting blade, and a joint portion. The cutting structure forming portion has a core portion and a surface portion provided on the attaching structure forming portion with the joint portion being interposed, and the surface portion covers at least a part of a surface of the core portion. The attaching structure forming portion includes a hard material including a hard component and one or two or more types of iron group elements, and the hard material has a Young's modulus of not more than 350 GPa. The core portion includes a cemented carbide material, and the surface portion includes PCD or CBN.

Holders are described herein providing secure clamping and/or positioning of cutting inserts. Briefly, a holder for a cutting insert comprises a base and a slot for receiving the cutting insert, wherein the slot forms an angle with the base ranging from 10 degrees to 60 degrees.

A cutting tool according to an aspect of the present disclosure includes a cutting edge portion which contains at least one of cubic boron nitride and polycrystalline diamond. The cutting edge portion includes a flank face, a negative land contiguous to the flank face, and a cutting edge formed by a ridgeline between the flank face and the negative land. At least one of the negative land and the flank face is provided with a plurality of recesses and a projection. The projection is formed by arranging the edges of adjacent recesses in contact with each other.