Provided is a structure for improving accuracy in attaching a cutting tool to a body and making it possible to increase the number of blades while the cutting tool is mounted on the body. A cutting insert 1 includes: an upper surface 10 that has a shape with a lengthwise direction LD and a widthwise direction SD; a lower surface that is located opposite to the upper surface 10; a peripheral side surface 30 that is formed so as to connect the upper surface 10 and the lower surface; cutting edges 51 and 52 that are respectively formed on an intersecting ridge line of the upper surface 10 and the peripheral side surface 30, and on an intersecting ridge line of the lower surface and the peripheral side surface 30, and each have a curved ridge line that extends in a lengthwise direction thereof; and a through hole 60 that penetrates from the upper surface 10 to the lower surface. End surfaces 31 and 32 located in the lengthwise direction LD of the upper surface 10 and the lower surface, of the peripheral side surface 30, are respectively inclined with respect to the upper surface 10 and the lower surface, and are parallel to each other. A reference surface 33 that is located opposite to the cutting edges 51 and 52, of the peripheral side surface 30, is a flat surface that is orthogonal to the upper surface 10 and the lower surface.

Provided is a cutting insert and a cutting tool equipped with the cutting tool improving the force to clamp the insert and improving the strength of the insert and the chip dischargeability. The cutting insert includes: an upper surface, which is a first end surface; a lower surface, which is a surface on an opposite side to the upper surface, and is a second end surface having an installing surface for installing a cutting tool; a screw hole which has an axial line penetrating from the upper surface to the lower surface; a peripheral side surface which is formed such that the upper surface and the lower surface are connected; a major cutting edge and an inner cutting edge which are formed in an intersecting region between the upper surface and the peripheral side surface, and an intersecting region between the lower surface and the peripheral side surface, respectively; and a constraining surface which is formed on the peripheral side surface so as to at least partially contact with a body. An angle of the major cutting edge and an angle of the constraining surface are different in a top view viewed from the upper surface, and the angle of the major cutting edge is smaller than the angle of the constraining surface.

A cutting insert includes a polygonal plate-shaped insert main body having two polygonal surfaces, a side surface having a flank, and a cutting edge to be formed in an intersection ridgeline portion between a rake face and the flank. The insert main body has a rotationally symmetrical shape with respect to an insert center line, and has a front-rear reversely symmetrical shape with respect to the polygonal surface. The cutting edge includes a corner cutting edge, a major cutting edge extending from an one end of the corner cutting edge, and a wiper cutting edge extending from an one end of the major cutting edge in a direction intersecting the major cutting edge at an obtuse angle. A first region is disposed where a clearance angle of the flank gradually decreases to a negative angle after continuously passing through 0° from a positive angle.

Provided is a cutting insert and a cutting tool equipped with the cutting tool improving the force to clamp the insert and improving the strength of the insert and the chip dischargeability. The cutting insert includes: an upper surface, which is a first end surface; a lower surface, which is a surface on an opposite side to the upper surface, and is a second end surface having an installing surface for installing a cutting tool; a screw hole which has an axial line penetrating from the upper surface to the lower surface; a peripheral side surface which is formed such that the upper surface and the lower surface are connected; a major cutting edge and an inner cutting edge which are formed in an intersecting region between the upper surface and the peripheral side surface, and an intersecting region between the lower surface and the peripheral side surface, respectively; and a constraining surface which is formed on the peripheral side surface so as to at least partially contact with a body. An angle of the major cutting edge and an angle of the constraining surface are different in a top view viewed from the upper surface, and the angle of the major cutting edge is smaller than the angle of the constraining surface.

A cutting insert includes a polygonal plate-shaped insert main body having two polygonal surfaces, a side surface having a flank, and a cutting edge to be formed in an intersection ridgeline portion between a rake face and the flank. The insert main body has a rotationally symmetrical shape with respect to an insert center line, and has a front-rear reversely symmetrical shape with respect to the polygonal surface. The cutting edge includes a corner cutting edge, a major cutting edge extending from an one end of the corner cutting edge, and a wiper cutting edge extending from an one end of the major cutting edge in a direction intersecting the major cutting edge at an obtuse angle. A first region is disposed where a clearance angle of the flank gradually decreases to a negative angle after continuously passing through 0 from a positive angle.

Provided is a structure for improving accuracy in attaching a cutting tool to a body and making it possible to increase the number of blades while the cutting tool is mounted on the body. A cutting insert 1 includes: an upper surface 10 that has a shape with a lengthwise direction LD and a widthwise direction SD; a lower surface that is located opposite to the upper surface 10; a peripheral side surface 30 that is formed so as to connect the upper surface 10 and the lower surface; cutting edges 51 and 52 that are respectively formed on an intersecting ridge line of the upper surface 10 and the peripheral side surface 30, and on an intersecting ridge line of the lower surface and the peripheral side surface 30, and each have a curved ridge line that extends in a lengthwise direction thereof; and a through hole 60 that penetrates from the upper surface 10 to the lower surface. End surfaces 31 and 32 located in the lengthwise direction LD of the upper surface 10 and the lower surface, of the peripheral side surface 30, are respectively inclined with respect to the upper surface 10 and the lower surface, and are parallel to each other. A reference surface 33 that is located opposite to the cutting edges 51 and 52, of the peripheral side surface 30, is a flat surface that is orthogonal to the upper surface 10 and the lower surface.

Provided is a structure for improving accuracy in attaching a cutting tool to a body and making it possible to increase the number of blades while the cutting tool is mounted on the body. A cutting insert 1 includes: an upper surface 10 that has a shape with a lengthwise direction LD and a widthwise direction SD; a lower surface that is located opposite to the upper surface 10; a peripheral side surface 30 that is formed so as to connect the upper surface 10 and the lower surface; cutting edges 51 and 52 that are respectively formed on an intersecting ridge line of the upper surface 10 and the peripheral side surface 30, and on an intersecting ridge line of the lower surface and the peripheral side surface 30, and each have a curved ridge line that extends in a lengthwise direction thereof; and a through hole 60 that penetrates from the upper surface 10 to the lower surface. End surfaces 31 and 32 located in the lengthwise direction LD of the upper surface 10 and the lower surface, of the peripheral side surface 30, are respectively inclined with respect to the upper surface 10 and the lower surface, and are parallel to each other. A reference surface 33 that is located opposite to the cutting edges 51 and 52, of the peripheral side surface 30, is a flat surface that is orthogonal to the upper surface 10 and the lower surface.

Provided is a structure for improving accuracy in attaching a cutting tool to a body and making it possible to increase the number of blades while the cutting tool is mounted on the body. A cutting insert 1 includes: an upper surface 10 that has a shape with a lengthwise direction LD and a widthwise direction SD; a lower surface that is located opposite to the upper surface 10; a peripheral side surface 30 that is formed so as to connect the upper surface 10 and the lower surface; cutting edges 51 and 52 that are respectively formed on an intersecting ridge line of the upper surface 10 and the peripheral side surface 30, and on an intersecting ridge line of the lower surface and the peripheral side surface 30, and each have a curved ridge line that extends in a lengthwise direction thereof; and a through hole 60 that penetrates from the upper surface 10 to the lower surface. End surfaces 31 and 32 located in the lengthwise direction LD of the upper surface 10 and the lower surface, of the peripheral side surface 30, are respectively inclined with respect to the upper surface 10 and the lower surface, and are parallel to each other. A reference surface 33 that is located opposite to the cutting edges 51 and 52, of the peripheral side surface 30, is a flat surface that is orthogonal to the upper surface 10 and the lower surface.