CUTTING INSERT

摘要

PROBLEM TO BE SOLVED: To divide and discharge in the proper winding length, by rounding in a spiral spring shape, without laterally dislocating chips, regardless of a difference in a chip thickness by a size of a feed quantity by grooving and cutting-off processing.SOLUTION: Inclined planes 51 and 52 of forming a low position toward a central part sandwiched by both lateral cutting edges 120, are formed on a rake face 40, and a recessed groove 60 is formed in the tip rear direction of including a front cutting edge 110 in a central part sandwiched by this. A groove width of the recessed groove 60 is gradually increased backward from a position of the cutting edge 110, and is gradually reduced thereafter, and is formed as the narrowest part in gradual reduction on the other side of a position P3 of the upper end 45 of a breaker wall 43 and in a rear position P2 more than a rear end position P1 of a positive rake angle, and is gradually increased up to the position P3 of the upper end 45 of the breaker wall 43 toward its rear, and assuming a groove width dimension of the front cutting edge 110 as W1, a groove width dimension of the narrowest part as W2 and a groove width dimension of the position P3 of the upper end 45 of the breaker wall 43 as W3, these are set in the dimensional relationship of W1