The present disclosure relates to a rhomboid-shaped double-sided turning insert having a convex cutting corner flanked by two flank faces, wherein the insert comprises, on each side: a rhomboid-shaped rake face opposite the face of the opposite side; a lateral cutting corner surface arranged adjoining and between the two flank faces; two flanking edges, each formed between a respective flank face and a rhomboid side of the rake face; a cutting edge formed by a straight primary cutting edge and a straight secondary cutting edge, formed between the lateral cutting corner surface and the rake face, arranged adjoining and between the two flanking edges, wherein the primary cutting edge is longer than the secondary cutting edge; and a chip-deflecting surface which is recessed and arranged inwardly of said cutting edge; wherein a lateral cutting corner surface of the insert, formed by the lateral cutting corner surfaces of a first and a second side, extends between the first side and second side cutting edges, wherein the primary cutting edge and secondary cutting edge are in reversed positions between the first and second sides.

A cutting insert according to an aspect includes a base portion and a cutting portion. The cutting portion includes a front end surface, an top surface, a first lateral surface, a second lateral surface, a front cutting edge, and a lateral cutting edge. The front cutting edge includes a first cutting edge and a second cutting edge, and a radius of curvature of the first cutting edge is greater than a radius of curvature of the second cutting edge.

A cutting insert in a non-limiting embodiment may include a first surface, a second surface, a third surface and a land surface. The first surface may include a first corner and a first side extended from the first corner. The land surface may be located between the first surface and the third surface and inclined relative to the first surface and the third surface. The land surface may include a first land surface located along the first corner, a second land surface located along the first side, and a third land surface having a concave shape which is adjacent to the second land surface and located further away from the first land surface than the second land surface.

A cutting insert may include an upper surface, a lateral surface, and a cutting edge including a boundary between the upper surface and the lateral surface. The upper surface may include a first rising face that extends upward and a second rising face that is connected to an upper side of the first rising face and extends upward. The first rising face may include a first region that extends along a corner portion and a second region that extends along a side portion. The second rising face may include a third region connected to the first region and a fourth region connected to the second region. An entirety of a boundary between the first region and the third region may be positioned above the cutting edge. A boundary between the second region and the fourth region may include a portion disposed below the cutting edge.

A turning insert includes a top surface, a bottom surface, and side surfaces connecting the top and bottom surfaces. A reference plane is located parallel to and between the top surface and the bottom surface. A center axis intersects and extends perpendicular to the reference plane. Three nose portions are formed symmetrically around the center axis. Each nose portion has a first cutting edge, a second cutting edge and a convex nose cutting edge connecting the first and second cutting edges. As seen in in a top view, the first and second cutting edges on the same nose portion form a nose angle of 25-50°. The first cutting edge includes a first sub-portion and a second sub-portion. A distance from the nose cutting edge to the first sub-portion is shorter than a distance from the nose cutting edge to the second sub-portion.

A straight line along the second line segment and a straight line along the fourth line segment form an acute angle. The straight line along the second line segment and the straight line along the third line segment form an obtuse angle. The straight line along the first line segment and the straight line along the fourth line segment form an obtuse angle. Each of the third curved portion and the fourth curved portion is larger in radius of curvature than the first curved portion and larger in radius of curvature than the second curved portion. In a direction perpendicular to the bottom surface, a distance between the top surface and the bottom surface is equal to a distance between the cutting edge and the bottom surface, or is shorter than the distance between the cutting edge and the bottom surface.

A turning insert includes a head portion connected to a stem portion. A CBN cutting edge includes a surface generating cutting edge and two major cutting edge portions, such that each major cutting edge portion forms an angle of 5-20° in relation to a tangent line of the cutting edge at a forward point of the cutting edge.

A cutting insert of one embodiment is provided with: an insert body having a top surface that has a corner section, a bottom surface, and side surfaces; a cutting edge that is positioned at an intersection between the top surface and the side surfaces, and includes a corner cutting edge, a first cutting edge and a second cutting edge; a rake face that slopes downward away from the cutting edge; and a first raised part that is positioned inside the rake face, and rises upward. The first raised part includes a protruding section that protrudes toward the corner cutting edge. The cutting insert is further provided with a second raised part that extends toward the first cutting edge and the second cutting edge from the protruding section, and has a convex curved shape in which, when viewed from above, the outer peripheral edge on the corner section side.

The invention relates to a cutting insert (1) for installation in carrier tools for machining workpieces, comprising a top side (2), a bottom side (3), and side surfaces (4) connecting the top side (2) and the bottom side (3), wherein a peripheral protective chamfer (5) having an upper edge (6) adjoining the top side (2) of the cutting insert (1) and having a lower edge (7) adjoining the side surfaces (4) is arranged at the transition from the top side (2) to the side surfaces (4), wherein the upper edge (6) forms cutting edges (9) and cutting corners (10) and, in the region of the cutting edges (9), the lower edge (7) transitions into a cutting-edge clearance angle surface (8) having an edge clearance angle of 3° to 11°. For improved edge stability in drawn cuts, it is proposed that, in the region of the cutting corners (10), the lower edge (7) of the protective chamfer (5) transitions into a corner clearance angle surface (11) having an edge clearance angle of 3° to 5°.

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.