An insert configured to be assembled to a tool for cutting a workpiece, includes: an upper surface including first to fourth upper corner portions formed in respective quadrants divided by a first imaginary vertical axis and a first imaginary horizontal axis that are perpendicular to each other; and a lower surface formed below the upper surface in a height direction and including first to fourth lower corner portions formed in respective quadrants divided by a second imaginary vertical axis and a second imaginary horizontal axis that are perpendicular to each other. A lower ridge portion protruding downward in the height direction is formed on the lower surface, and extends across the second and fourth lower corner portions, which are symmetrical with respect to a center of the lower surface

A cutting edge has a corner cutting edge, a flat drag, and a main cutting edge. The rake surface has a first rake surface portion, a second rake surface portion, and a third rake surface portion. The first rake surface portion has a first inclined surface inclined at a first angle. The second rake surface portion has a second inclined surface inclined at a second angle greater than the first angle. The first end portion and the second end portion are higher than the reference surface in a direction perpendicular to the reference surface, and the main cutting edge extends so as to intersect the reference surface when viewed in a direction parallel to the reference surface. A first step portion rising from the third rake surface portion and continuous with the first rake surface portion is provided on the rake surface.

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 cutting insert for a milling tool, having a first side, a second side which is identical to the first side and a circumferential surface which extends between the first and the second sides, with a bore which extends along a bore axis. The cutting insert is 120 rotationally symmetrical with respect to the bore axis and includes on each of the first side and the second side three identically formed cutting regions, respectively, which are situated at a transition between the first side and the circumferential surface or at a transition between the second side and the circumferential surface, respectively. Each of the in total six cutting regions includes a first rectilinear cutting edge, a second rectilinear cutting edge, and a third arcuate cutting edge, wherein a first end of the first cutting edge is connected to a first end of the third cutting edge, and a first end of the second cutting edge is connected to a second end of the third cutting edge, wherein the first and the second cutting edges are of same length. The cutting insert includes on the first side a first contact surface which extends orthogonally to the bore axis and lies in a first contact plane, and on the second side includes a second contact surface which extends orthogonally to the bore axis and lies in a second contact plane, and wherein each of the first cutting edges are connected at their second ends, which are located opposite the first ends, to one of a total of six arcuate edges, a vertex of which is located between the first and the second contact planes.

A cutting insert may include a first surface having a polygonal shape, a second surface, a third surface and a cutting edge. The first surface may include a first corner, a first side, a first inclined surface located along the first side, and a second inclined surface located along the second side. In a plan view of the first surface, a width of the first inclined surface in a direction orthogonal to the first side may become larger as approaching the second side. A width of the second inclined surface in a direction orthogonal to the second side may become larger as approaching the first side.

Provided is a cutting insert capable of suppressing edge fracture when a work having high hardness is machined. A cutting insert includes two end surfaces having a plurality of corner parts and opposed to each other, a peripheral side surface extending between the two end surfaces, and a cutting edge formed at an intersecting edge between at least one of the two end surfaces and the peripheral side surface. The cutting edge has at least a first corner edge, a second corner edge, a major cutting edge, and an end cutting edge. The end cutting edge has a circular-arc shape, which projects outward, as viewed from the side of the end surface. The end cutting edge has a width which is from 15% to 50% of the width of the cutting insert. The end cutting edge has an arc radius which is from to 1/1 of the width of the cutting insert.

An indexable cutting insert has a first corner edge forming a front tip of a cutting edge portion configured to project furthest in the direction of an axis of rotation of an end mill tool receiving the insert. A major cutting edge is descending to come closer to the lower surface of the insert along its extension away from the first corner edge. The minor cutting edge extends from the first corner edge while descending from a point of the cutting edge portion most distant to the lower surface all the way to an inner corner of the insert and has a length of 80%-95% of the length of the major cutting edge including a second corner edge in a side elevation view of the cutting insert.

In an end view, a cutting insert 10 comprises a first connecting part 30A which is inclined such that the first connecting part 30A travels in a first direction as it heads away from a second peripheral side surface part 18 and approaches a fourth peripheral side surface part 22, and also comprises a second connecting part 30B which is connected to a center point serving as an end of the first connecting part 30A and which is inclined such that the second connecting part 30B travels in a third direction as it heads away from the second peripheral side surface part 18 and approaches the fourth peripheral side surface part 22. A cutting edge 24 comprises: a first cutting edge part 24A which is formed on the first connecting part 30A so as to be distant, by a first distance L1, from a virtual plane PR1 including a center point C1; a second cutting edge part 24B which has, in a side view, a concave circular-arc shape having a second curvature radius smaller than a first curvature radius and which is formed on the second connecting part 30B so as to be distant, by a second distance L2 greater than the first distance L1, from the virtual plane PR1; and a third cutting edge part 24C connecting the first cutting edge part 24A and the second cutting edge part 24B.

In a cutting insert of an embodiment of the present invention, an upper surface includes a first corner, and a second corner and a third corner respectively adjacent to both sides of the first corner. The upper surface sequentially includes a rake surface located along an upper cutting edge and inclined toward a lower surface as going inward from the upper cutting edge at a rake angle on a basis of a perpendicular plane perpendicular to a central axis extending between the upper and lower surfaces, and a connection surface located more inward than the rake surface and inclined toward the lower surface as going inward at a connection angle on the basis of the perpendicular plane. An intersecting part of the rake surface and the connection surface includes a highest position in a portion of the intersecting part corresponding to the minor rake surface. A cutting tool with the cutting insert, and a method of producing a machined product by using the cutting tool are also provided.

A milling insert for a side and face milling tool includes an upper side defining an upper extension plane, a lower side defining a lower extension plane, and a side surface extending between the upper and the lower sides around a periphery of the insert that includes a main radial clearance surface, two opposite axial clearance surfaces and two corner clearance surfaces. At least one cutting edge is formed in a transition between the upper and the side surfaces, wherein each cutting edge includes a main cutting edge extending above the main radial clearance surface and two corner cutting edges extending above the corner clearance surfaces on opposite sides of the main cutting edge. The main cutting edge slopes downward toward a midpoint of the main cutting edge and the main cutting edge and the main radial clearance surface slope outward from the corner cutting edges toward the midpoint.