A cutting tool having a tool holder, cutting insert and clamping member. The tool holder includes an elongated supporting surface extending in a rearward-to-forward direction. The cutting insert has a central portion and three cutting portions, the central portion having two opposing side surfaces and three spaced apart locating surfaces defining a first imaginary triangle. The cutting insert is indexable about a central axis intersecting the two side surfaces. Each locating surface intersects two of three bisector planes containing the central axis and bisecting respective corners of the first imaginary triangle, and the cutting edge of each cutting portion is located entirely outside of the first imaginary triangle. In each index position the clamping member is located entirely rearward of a first vertical plane containing the central axis and perpendicular to the rearward-to-forward direction, and one of the locating surfaces is in clamping contact with the supporting surface.

A rotary cutting tool insert according to one embodiment of the present invention includes: an annular rake face provided with at least one recess portion; and a cutting edge formed at an outer circumference of the rake face, the recess portion having a width of more than or equal to 1.2 mm and less than or equal to 3.0 mm in a circumferential direction of the rake face, a distance between the cutting edge and an end of the recess portion at the outer circumference side of the rake face being more than or equal to 0.1 mm and less than or equal to 0.5 mm. According to the rotary cutting tool insert according to the one embodiment of the present invention, roughness of a processed surface and vibration due to a cutting process can be prevented.

A cutting insert of one aspect includes a top surface including a corner portion and a pair of side portions each adjacent to the corner portion, a bottom surface, a side surface located between the top surface and the bottom surface, and a corner cutting edge disposed at the corner portion. In such a cutting insert, the top surface includes a first rake surface located along the corner cutting edge, a raised portion located farther on the inner side than the first rake surface, and a second rake surface located between the corner cutting edge and the raised portion. Moreover, a rake angle at a first region of the second rake surface corresponding to a center of the corner cutting edge is greater than a rake angle at a second region of the second rake surface located beside the first region.

A double-sided cutting insert includes two end surfaces that each includes major rake surfaces adjacent major cutting edges that form first angles with planes of major side surfaces of the insert, and a central support surface forming a second angle with the planes of the major side surfaces. Each end surface further includes major intermediate surfaces between the major rake surfaces and the central support surface. The major intermediate surfaces form third angles with the planes of the major side surfaces that are greater than the first angles and smaller than the second armies when measured in a central plane that extends along a central axis of the hole and is generally perpendicular to the planes of the major side surfaces and planes of the central support surfaces.

A cutting insert includes a rake face, a flank face, a cutting edge formed at a ridge where the rake face and the flank face intersect, a land provided on the rake face along the cutting edge, a breaker groove provided in the rake face inside of the land, and a curved surface formed between a groove surface of the breaker groove and the land. A radius of curvature of the curved surface is 0.5 mm or greater.

A cutting insert is used in a cutting edge replaceable rotary cutting tool. The cutting insert includes a first cutting edge formed on an intersecting ridge portion between a first end surface of two opposite end surfaces and a circumferential side surface, and a first depressed portion formed along a part of the first cutting edge. The first depressed portion is provided to form a larger rake angle at the first cutting edge than that at a part not having the first depressed portion of the first cutting edge.

A workpiece at least includes a first outer surface, a second outer surface and a third outer surface. The third outer surface intersects the first outer surface and the second outer surface to define an extrusion-acting portion having an extruding portion. The workpiece can be used to machine a cutter in an entire or a trimmed portion thereof. Thereupon, rapid production of cutters by molding machines can be realized, and blades of the molding machine for machining the cutter become replaceable. While a blade portion is machining, the extrusion-acting portion is applied to support and guide the workpiece, such that the surface machined by the blade portion can be extruded and polished simultaneously. Thus, machining qualities of the cutter, including finish, straightness and roundness, manufactured by applying the workpiece for the molding machine can be significantly improved.

A cutting insert according to one embodiment of the present invention comprises an upper surface, a lower surface, a lateral surface, a cutting edge, and a fastening hole, wherein the cutting edge includes a main cutting edge, a nose R part connected to the main cutting edge, and a sub-cutting edge connected to the nose R part, the upper surface includes a land part adjacent to the cutting edge, an inclined surface downwardly inclined from the land part, and an upper surface bottom part extending from the inclined surface, first and second protrusion parts are formed respectively, in which the first protrusion part is connected to a main cutting edge land part and formed on a main cutting edge inclined surface at a portion at which a nose R part inclined surface ends and the second protrusion part is connected to a sub-cutting edge land part and formed on a sub-cutting edge inclined surface at a portion at which the nose R part inclined surface ends, and no protrusion is present on the nose R part inclined surface.

A cutting insert of one aspect includes a top surface including a corner portion and a pair of side portions each adjacent to the corner portion, a bottom surface, a side surface located between the top surface and the bottom surface, and a corner cutting edge disposed at the corner portion. In such a cutting insert, the top surface includes a first rake surface located along the corner cutting edge, a raised portion located farther on the inner side than the first rake surface, and a second rake surface located between the corner cutting edge and the raised portion. Moreover, a rake angle at a first region of the second rake surface corresponding to a center of the corner cutting edge is greater than a rake angle at a second region of the second rake surface located beside the first region.

A cutting tool having a tool holder, cutting insert and clamping member. The tool holder includes an elongated supporting surface extending in a rearward-to-forward direction. The cutting insert has a central portion and three cutting portions, the central portion having two opposing side surfaces and three spaced apart locating surfaces defining a first imaginary triangle. The cutting insert is indexable about a central axis intersecting the two side surfaces. Each locating surface intersects two of three bisector planes containing the central axis and bisecting respective corners of the first imaginary triangle, and the cutting edge of each cutting portion is located entirely outside of the first imaginary triangle. In each index position the clamping member is located entirely rearward of a first vertical plane containing the central axis and perpendicular to the rearward-to-forward direction, and one of the locating surfaces is in clamping contact with the supporting surface.