A cutting insert of a substantially horizontal cylindrical segment shape and having top and bottom surfaces with a circular segment shape. The cutting insert has a convex side and a flat side, a top cutting edge which is formed where the convex side and the top surface meet, and a bottom cutting edge which is formed where the convex side and the bottom surface meet. The cutting insert includes a hole extending from the convex side towards the flat side. The hole is positioned at a center of a surface of the flat side.

A cutting insert according to one aspect has a flat plate shape including a first main surface having a polygonal shape, a second main surface located opposite to the first main surface, and an outer peripheral surface located between the first main surface and the second main surface. The cutting insert includes a cutting portion located in regions including at least a corner portion of the first main surface, and a main body portion located in a region other than the corner portion. A thickness of the main body portion is larger than a thickness of the cutting portions, and the main body portion includes a recessed portion or a protruding portion located in the outer peripheral surface thereof.

Embodiments of a cutting insert are provided. The cutting insert includes an upper surface, a lower surface, a plurality of side surfaces extending between the upper surface and the lower surface, an insert hole extending through the upper surface and the lower surface, and a corner portion provided with a cutting edge. At least one of the upper surface and the lower surface has a plurality of recesses extending between the insert hole and the corner portion. The plurality of recesses includes a first recess into which one portion of the mounting portion is inserted when the cutting insert is supported by the mounting portion, and a second recess into which another portion of the mounting portion is inserted when the cutting insert is supported by the mounting portion. The second recess has a side wall spaced apart from another portion of the mounting portion.

To provide a cutting insert such that a tool body can sufficiently hold the cutting insert even if one of cutting parts is broken. The cutting insert includes two side surfaces opposed to each other, a fixing hole passing through the centers of the two side surfaces, and an outer circumferential surface that is disposed between the outer circumferential edges of the two side surfaces and are connected to the outer circumferential edges of the two side surfaces. The outer circumferential surface includes four cutting parts, a first outer circumferential surface part that is disposed between the first cutting part and the second cutting part, and a second outer circumferential surface part that is opposed to the first outer circumferential surface part and is disposed between the third cutting part and the fourth cutting part. In a side view of the side surfaces from the axial direction of the fixing hole, the first outer circumferential surface part and the second outer circumferential surface part each have the center recessed toward the fixing hole, and a virtual arc having the same diameter as the diameter of the circumcircle of the cutting insert is in contact with two points on each of the outer circumferential surface parts.

A tool body to which a replaceable cutting insert is fixed includes: a holder: an insert mounting seat that is provided on a first surface of the holder; a clamp member that constrains the cutting insert placed on the insert mounting seat; and an operating member that presses a pressure receiving surface of the clamp member. The clamp member has the pressure receiving surface, a spherical head portion that is formed into a spherical crown shape, and a hook portion that protrudes to a side opposite to a side of the spherical head portion when seen from a side of the first surface. The insert mounting seat supports the clamp member to be swingable with the spherical head portion as a fulcrum, and the hook portion contacts a diameter reducing portion that is formed on an inner peripheral surface of an mounting hole for the cutting insert in a state in which the pressure receiving surface is pressed.

A cutting insert and a cutting tool which can suppress lowering of blade-edge positional accuracy while holding by a holder having a small thickness is enabled are provided.

The cutting insert includes a first end surface, a second end surface, and a peripheral side surface connected to the first end surface and the second end surface and having a rake face, a flank, and a cutting edge formed in a connection region between the rake face and the flank, and a through hole penetrating the first end surface and the second end surface is formed. It is the cutting insert including a first contact surface substantially perpendicular to a center axis direction of the through hole and capable of contacting the holder, a second contact surface substantially in parallel with the center axis direction of the through hole, substantially perpendicular to a plane including the first contact surface and capable of contacting the holder, and a third contact surface inclined with respect to the center axis direction of the through hole and capable of contacting the holder, and a cutting tool including the cutting insert as above.

Provided is a cutting insert having two cutting parts that is capable of entering a workpiece more deeply and easily supports machining of a groove or hole having a small diameter in a workpiece. A cutting insert includes: a body having at least an inner surface to be fixed to a tool body of a cutting tool and an outer surface opposed to the inner surface; and two cutting parts protruding in opposite directions in a longitudinal direction of the body. The cutting part includes: a cutting upper surface; a cutting front surface; and a first cutting side surface and a second cutting side surface. A front cutting edge is located on an edge between the cutting upper surface and the cutting front surface. In a projection view of the body as seen from the longitudinal direction, the cutting upper surfaces of the two cutting parts are oriented in directions opposed to each other, and front cutting edges of the two cutting parts are disposed so as to be more away from each other as being closer to the first cutting side surface from the second cutting side surface.

A non-indexable, one-sided cutting insert includes opposite insert side surfaces which define an insert width therebetween, opposite insert front and rear surfaces which extend between the insert side surfaces and define an insert depth therebetween and opposite insert top and bottom surfaces which extend between the insert side surfaces and the insert front and rear surfaces. The insert top and bottom surfaces define an insert height therebetween. The insert further includes a main cutting edge formed at an intersection between the insert top and front surfaces. A maximum value of the insert width is smaller than minimum value of the insert height, and a minimum value of the insert depth. The insert includes a deep opening which opens out only to the insert bottom surface and defines an opening depth. A depth ratio defined between the opening depth and the insert height is greater than 0.3.

A cutting insert according to the present disclosure includes a first raised portion and a second raised portion stepped from the first raised portion, which are formed on a top surface and along a center line connecting the center of the corner portion and the center of the top surface. The first raised portion is located closer to the corner portion than the second raised portion is, and the first raised portion is inclined downwardly from the second raised portion toward the corner portion. The second raised portion is formed at a higher position from the bottom surface than the first raised portion, and a side portion connected to the first raised portion is inclined downwardly from the second raised portion toward the first and second cutting edges.

A cutting insert having a first end surface, a second end surface, and a peripheral side surface. The peripheral side surface includes a rake surface, a front flank and a first cutting edge located in an intersecting edge between the rake surface and the front flank. The first end surface includes a central surface and a side flank located closer to the front flank as compared to the central surface. An intersecting edge between the central surface and the peripheral side surface serves as a first edge, and an intersecting edge between the side flank and the peripheral side surface serves as a second edge, and an angle formed by the first cutting edge and the first edge serves as a first angle α, and an angle formed by the first cutting edge and the second edge serves as a second angle β, wherein α is smaller than β.