CUTTING INSERT AND CUTTING TOOL

摘要

PROBLEM TO BE SOLVED: To enable produced and discharged cutting chips to be bent in a direction of separating from a cutting object and fragmented by themselves under their bending action in the case where the cutting object is worked in the outer diameter at a right angle or a depth setting angle approximate thereto with a cutting insert that has a linear cutting edge extending from a nose and is provided in a cutting face with a breaker groove along the cutting edge so as to make a positive rake angle.SOLUTION: At a part closer to the tip of a linear cutting edge 107, a caving recess 121 is formed into a rake face 103 to form a concave cutting edge 125 with a ridge line made by a cross of an inner face 123 with a flank 113, thereby making this concave cutting edge 125 have a negative rake angleβ. In lathe turning with the concave cutting edge 125 as such a depth setting amount as to receive cutting, a cutting resistance at the part of the concave cutting edge 125 becomes relatively large. Therefore, a thickness of produced cutting chips becomes relatively thick at the part of the concave cutting edge 125, so that the cutting chips bend in a direction of separating from a cutting object due to a difference in thickness.