US Patent 11179785 Cutting insert and indexable edge rotary cutting tool

A cutting insert includes a main surface formed in a substantially parallelogram shape and having a pair of acute angle corner portions and a pair of obtuse angle corner portions, a seating surface that faces a side opposite to the main surface, a side surface that connects the main surface and the seating surface to each other, a corner cutting edge disposed in the acute angle corner portion, and a main cutting edge and a subsidiary cutting edge which are respectively disposed in a pair of side ridge portions of the main surface located each other across the acute angle corner portion. A mounting hole into which the fixing member is inserted penetrates the main surface and the seating surface. The main cutting edge is inclined at an inclination angle equal to or larger than 8° with reference to a plane perpendicular to an axial direction of the mounting hole.