Rotary tool

A rotary tool comprising:

• a cylindrical body including a rotational axis and extending from a first end to a second end;
• a plurality of outer peripheral cutting edges positioned on an outer periphery of the body to form a spiral shape from a side of the first end toward a side of the second end, wherein rotational trajectories of the plurality of outer peripheral cutting edges do not entirely overlap with each other;
• and
• a discharge groove positioned along the plurality of outer peripheral cutting edges, wherein,
• in a cross section of a rotational trajectory of the rotary tool including the rotational axis,
• the plurality of outer peripheral cutting edges comprise:
• a first convex section having a convex curved shape, a second convex section having a convex curved shape and positioned adjacent to the first convex section on the side of the second end,
• a first concave section having a concave curved shape and positioned contiguously on the side of the second end with respect to the first convex section, and a second concave section having a concave curved shape and positioned contiguously on the side of the second end with respect to the second convex section,
• the first convex section comprises:
• a first region having a convex curved shape and including an apex in the first convex section and
• a second region having a convex curved shape and positioned between the first region and the first concave section,
• the second convex section comprises:
• a third region having a convex curved shape and including an apex in the second convex section and
• a fourth region having a convex curved shape and positioned between the third region and the second concave section,
• a first radius of curvature of the first region is greater than a second radius of curvature of the second region and a third radius of curvature of the third region is greater than a fourth radius of curvature of the fourth region.