Double-sided cutting insert and cutting tool including same

A cutting tool rotated about a rotation axis, comprising:

• a double-sided cutting insert;
• a shank having a plurality of insert pockets configured such that the cutting insert is mounted thereto;
• and
• a clamp screw configured to fix the cutting insert to one of the plurality of insert pockets,
• wherein the cutting insert comprises:
• a through bore perforated in a first central axis;
• first and second end surfaces formed identically and located opposite to each other in the first central axis;
• a peripheral side surface disposed between the first and second end surfaces and including a plurality of seating side surfaces disposed at an equal interval in a circumferential direction of the first central axis;
• and
• first and second cutting edges formed identically and disposed at an intersection between the first end surface and the peripheral side surface and at an intersection between the second end surface and the peripheral side surface, respectively, each of the first and second cutting edges including a plurality of partial cutting edges connected one after another in the circumferential direction and curved convexly when the cutting insert is viewed from a plan view,
• wherein each of the plurality of partial cutting edges includes a first circular arc portion curved convexly when the cutting insert is viewed from a side view, and a second circular arc portion extending from the first circular arc portion and curved concavely when the cutting insert is viewed from the side view,
• wherein, when the cutting insert is viewed from the plan view, two second circular arc portions located opposite to each other with reference to the first central axis are disposed in a diagonal direction of the cutting insert,
• wherein each of the plurality of seating side surfaces is spaced apart from the first circular arc portion in a radially outward direction of the first central axis, and is disposed so as to be perpendicular to an imaginary line, which passes through the first central axis and a midpoint of the first circular arc portion and is orthogonal to the first central axis when the cutting insert is viewed from the side view,
• wherein each of the plurality of insert pockets includes:
• a bottom wall positioned in the rotation direction of the cutting tool and having a threaded bore to which the clamp screw is fastened, wherein one of the first and second end surfaces is seated on the bottom wall;
• and
• at least two side walls on which at least two seating side surfaces among the plurality of seating side surfaces are seated respectively, and
• wherein the bottom wall is inclined with respect to the rotation direction and is contacted to one of the first and second end surfaces such that the first circular arc portion and the second circular arc portion form a cutting trajectory becoming a portion of a perfect circle.