A cutting insert includes an upper surface having a circular cutting edge, a lower surface opposite the upper surface, an exterior sidewall between the upper surface and the lower surface, and an interior sidewall defining a hole extending from the upper surface to the lower surface. The interior sidewall includes an upper interior sidewall portion and a lower interior sidewall portion. The lower interior sidewall portion increases in radius with respect to a downward direction of the cutting insert. The lower interior sidewall portion includes a plurality of recessed portions positioned about a circumferential direction of the lower interior sidewall portion.

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.

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.

Provided is a cutting insert in which cutting edges in a plurality of sections can be used, and it is possible to keep chips, which are discharged from a cutting edge in a section that is being used, from damaging an unused cutting edge in an adjacent section. An edge where an upper surface and a peripheral side surface intersect is divided into a plurality of sections AB, BC, CD, and so on. In each of the plurality of section, the section AB, for example, includes one minor cutting edge and one major cutting edge that is longer than the minor cutting edge. The major cutting edge is inclined at an angle α to be away from a lower surface gradually while extending away from the minor cutting edge. A height position of the upper surface in an up-down direction in which the upper surface and the lower surface oppose each other does not change as the upper surface extends toward the attachment hole, or the height position decreases in a direction from the upper surface toward the lower surface.

A polygonal cutting blade having a circular arc-shaped groove in a hole includes a blade body composed of an upper surface, a lower surface and a plurality of main side surfaces connecting the upper surface and the lower surface. The blade body has a central hole penetrating through the upper surface and the lower surface, and is centrally symmetrical about a central axis of the central hole. At least one set of positioning side surface comprised of adjacent two of the main side surfaces is provided. An inner surface of the central hole has at least one circular arc-shaped groove fitting with a fastening screw for fixing the cutting blade. The circular arc-shaped groove directly faces toward an intersection of the two main side surfaces of the set of positioning side surface. A groove central axis of the circular arc-shaped groove has an offset distance from the central axis.

The present disclosure provides a cutting insert that is economical and can be stably fixed to a tool body. A first edge line (10R) of a cutting insert (2) is a rectangle having a first side (11) and a third side (13) as long sides and a second side (12) and a fourth side (14) as short sides. Cutting edges are formed at the first side (11), the second side (12) and the third side (13); on the other hand no cutting edge is formed at the fourth side (14). At a second edge line (20R) having the same shape as the first edge line (10R), a sixth side (22) where a cutting edge is formed is opposite to the fourth side (14), and an eighth side (24) where a cutting edge is not formed is opposite to the second side (12). A peripheral side surface (30) includes a fourth side surface (34) facing the fourth side (14) and the sixth side (22). The fourth side surface (34) extends from a first end surface (10) to a second end surface (20) and is inclined in a direction from the second side (12) to the fourth side (14).

A cutting insert includes a cutting edge portion, and the cutting edge portion includes a bottom cutting edge forming an arc shape that protrudes toward a front end side in a central axis direction, an outer peripheral cutting edge forming an arc shape that protrudes toward an outside in a radial direction, and a cutting edge of corner that connects an outer end of the bottom cutting edge in the radial direction and a front end of the outer peripheral cutting edge in the central axis direction and forms an arc shape that protrudes toward a front end outer circumferential side. The bottom cutting edge and the outer peripheral cutting edge are formed so as to form a linearly symmetric shape together with respect to an imaginary straight line that passes through an arc central point of the cutting edge of corner and intersects the central axis.

An insert may include a base member and a resin layer located on the base member. The base member may include a first surface, a second surface, and a cutting edge. The first surface includes a rake surface region. The second surface may be adjacent to the first surface and includes a flank surface region. The cutting edge may be located in at least a part of a ridge line at which the first surface intersects with the second surface. The resin layer may not be located on the second surface but may be located on the first surface.

What is presented is a cutting insert including a polygonal plate-shaped insert main body that includes: two polygonal surfaces; a side surface; and a cutting edge, the insert main body has a mounting hole that is centered on an insert center line passing through centers of the two polygonal surfaces, the cutting edge includes a major cutting edge extending from a first end of a corner edge located at a corner of the polygonal surface, and, in the opening of the mounting hole, a plurality of protrusions protruding with respect to a boss surface around an opening of the mounting hole are formed at intervals in a peripheral direction in an inner periphery side region of the major cutting edge.

A cutting body rotatable about a tool axis has an insert receiving pocket with a seat surface at an axial forward end thereof. The seat surface has a plurality of abutment elements, including an axial abutment element having an axially forward facing abutment surface and at least one radial abutment element. In a top view of the insert receiving pocket, the axially forward facing abutment surface forms an external acute clamping angle with a radially outward facing pocket wall. A rotary cutting tool includes the cutting body, and a cutting insert removably secured in the insert receiving pocket, having a base surface in contact with the seat surface. The at least one radial abutment element occupies or is occupied by at least one radial abutting element of the base surface, and the axially forward facing abutment surface is in contact with an axial abutting surface of the base surface.