A cutting insert may include a first surface having a polygonal shape, a second surface, and a cutting edge located on a ridge line where the first surface intersects with the second surface. The first surface may include a first corner, a second corner, a third corner, a first side, and a second side. In a plan view of the first surface, the first side may have a straight line shape or a convex shape protruded outward relative to a first imaginary line connecting the first corner and the second corner, and the second side may have a concave shape recessed inward relative to a second imaginary line connecting the first corner and the third corner.

There is provided a cutting insert which is capable of cutting by using either one of both surfaces and is stably supported by a tool body. Each of a first end surface and a second end surface of a cutting insert includes a first inclined surface which is inclined from a diagonal line by which a corner portion connecting a first peripheral side surface and a second peripheral side surface and a corner portion connecting a third peripheral side surface and a fourth peripheral side surface are joined toward a corner portion connecting the first peripheral side surface and the fourth peripheral side surface such that a distance to an imaginary plane decreases, and a second inclined surface which is inclined from the diagonal line toward a corner portion connecting the second peripheral side surface and the third peripheral side surface such that a distance to the imaginary plane decreases.

An object of this disclosure is to provide a cutting insert that is shaped so that a major cutting edge is not damaged easily. In the cutting insert, a major cutting edge, a corner edge, a flat cutting edge and an inner cutting edge are formed on at least an upper surface, a protruding portion protruding outward is formed in a major cutting edge side surface portion of a side surface that corresponds to the major cutting edge, and a first section is formed in which, when viewed from above, the protrusion amount becomes smaller as the protruding portion separates from the corner edge. Furthermore, the cutting insert includes a first clearance angle changing portion in which a clearance angle becomes smaller as a major cutting edge flank portion formed in a major cutting edge side surface portion separates from the corner edge, and a second clearance angle changing portion in which the clearance angle becomes larger as the major cutting edge flank portion separates from the corner edge, wherein the first clearance angle changing portion is preferably positioned closer to the corner edge than the second clearance angle changing portion is, and, of end portions of the first clearance angle changing portion, the value of the clearance angle at a distal end portion from the corner edge is preferably negative.

A milling tool includes a main body and a plurality of cutting inserts with respective cutting edges. The main body has an end face and a barrel-shaped curved lateral face. A first group of the plurality of cutting inserts are fastened on the end face, a second group of the plurality of cutting inserts are fastened on the barrel-shaped curved lateral face, and the respective cutting edges describe a barrel shape. Each one of the plurality of cutting inserts may be designed as an indexable insert.

A milling tool (10) comprises a shank section (12) and a head (14), the head being provided on a tip end side of the shank section and having cutting edges. The head (14) includes an expanding diameter section (14a) and a contracting diameter section (14b), the expanding diameter section gradually increasing in diameter as it spans toward the tip end from a base end portion adjoining the shank section (12), and the contracting diameter section gradually decreasing in diameter as it spans toward the tip end from a maximum diameter section (14c). At least one cutting edge (20, 22) is provided on each of the expanding diameter section (14a) and the contracting diameter section (14b). At least one tip-end cutting edge (32) that extends from the contracting diameter section to a center axis of the milling tool is provided on a tip end portion of the head.

A cutting insert for a rotary cutting tool has a second surface that includes a second seating surface having a shape of a flat surface. The first cutting edge has a first main cutting edge portion and a first sub cutting edge portion. The second cutting edge has a second main cutting edge portion and a second sub cutting edge portion. When viewed in a direction from the first surface toward the second surface, at least a portion of the second sub cutting edge portion is located outside the first main cutting edge portion, and at least a portion of the first sub cutting edge portion is located outside the second main cutting edge portion. When viewed in the direction from the first surface toward the second surface, each of the first sub cutting edge portion and the second sub cutting edge portion has a shape of a curved line.

A cutting tool which may be used in machining various material may include a body and one or more cutting elements associated therewith. In one example, the cutting element(s) may comprise a superhard table, such as a polycrystalline diamond table. In some embodiments, the polycrystalline diamond table may have a diamond density of approximately 95 percent volume or greater. In some embodiments, the thickness of the superhard table may be approximately 0.15 inch. In some embodiments, the superhard table may include a chip-breaking feature or structure. Methods of shaping, finishing, or otherwise machining materials are also provided, including the machining of materials comprising titanium.

A cutting insert of the present disclosure includes a top surface, a bottom surface, a side surface, and a corner cutting edge, a first cutting edge, a second cutting edge and a third cutting edge formed at a ridge line formed by the side surface and the top surface. The corner cutting edge has a first end and a second end. The first cutting edge extends from the first end in a first direction. The second cutting edge extends from the second end in a second direction. The third cutting edge extends from the second cutting edge in a third direction. The top surface has a first rake face adjacent to the first cutting edge, a second rake face adjacent to the second cutting edge, and a third rake face adjacent to the third cutting edge.

An assembled chamfer mill comprises a tool holder, an extension shaft, and chamfer bits locked to two ends of the extension shaft. The chamfer bits each have upper blades and lower blades for chamfering the edges of a workpiece simultaneously. The length of a shaft body of the extension shaft may be set in various sizes. Depending on the thickness and shape of the workpiece, the shaft body having an appropriate length is selected, so as to control the distance between the two chamfer bits. Another extension shaft may be provided to connect a further chamber bit for chamfering the edges of the workpiece simultaneously.

A cutting insert which is excellent in both cutting edge strength and chip evacuation is provided. A corner edge of the cutting insert is formed in an arc shape. In a direction perpendicular to a rotation axis of a body, a width of the corner edge is 40% or more and 50% or less of a width of the cutting insert. An upper surface has a negative land which is formed along a cutting edge and has a negative angle. The angle of the negative land increases from one end, which is connected to an inner cutting edge, of both ends of the corner edge toward the other end.