IMPROVED TYPE CUTTING TOOL AND CUTTING INSERT THEREFOR

摘要

PURPOSE: To form a uniform-radius curved cutting portion by mounting in a cavity a freely-dividing cutting insert with a flank having a certain relief angle with respect to a line parallel to a main polygonal face and with the main polygonal face intersecting side faces at preset angles to form rake faces. CONSTITUTION: A first main polygonal face 18 has a protrusion 26 inclined upward thereof. The protrusion 26 intersects side faces to form curved cutting edges 28 at the sides of a cutting insert. The protrusion 26 forms a flank 30 of an insert. The relief angle Q of the flank 30 is measured on the first main polygonal face with respect to a line 34 parallel to a second main polygonal face of the cutting insert. The relief angleθis a randomly given angle of about 5-25 degrees. The second main polygonal face intersects the side faces at an angle of at least 90 degrees to form rake faces.