Patent ID: 8469638

Claim:
A cutting insert ( 26 ), for internal grooving comprising: a front surface ( 34 ); a rear surface ( 36 ); a peripheral surface ( 38 ) extending between the front and rear surfaces ( 34 , 36 ); a cutting portion ( 40 ); a mounting portion ( 42 ) comprising: a lower rear surface ( 50 ); and exactly two insert protuberances, a first insert protuberance ( 52 ) and a second insert protuberance ( 54 ), protruding from the lower rear surface ( 50 ) in a direction away from the front surface ( 34 ), each insert protuberance ( 52 , 54 ) comprising: two insert protuberance side surfaces ( 58 ) extending in a direction away from the lower rear surface ( 50 ); and an insert protuberance upper surface ( 56 ) located between the two insert protuberance side surfaces ( 58 ) and distal the lower rear surface ( 50 ); and a through bore ( 28 ), passing through the front and rear surfaces ( 34 , 36 ); wherein the two insert protuberance side surfaces ( 58 ) on the first insert protuberance ( 52 ) form first and second insert protuberance side surfaces ( 64 , 66 ) that converge towards each other in a direction from the peripheral surface ( 38 ) towards the through bore ( 28 ), and the first and second insert protuberance side surfaces ( 64 , 66 ) form a protuberance wedge angle ( 2 α) therebetween having a bisector (B); the two insert protuberance side surfaces ( 58 ) on the second insert protuberance ( 54 ) form third and fourth insert protuberance side surfaces ( 68 , 70 ) that converge towards each other in a direction from the peripheral surface ( 38 ) towards the through bore ( 28 ); in a rear view of the cutting insert ( 26 ) a minimum first distance (L 1 ) between an imaginary line laying on the first insert protuberance side surface ( 64 ) and the fourth insert protuberance side surface ( 70 ) is greater than a second distance (L 2 ) between the second insert protuberance side surface ( 66 ) and an imaginary line laying on the third insert protuberance side surface ( 68 ); and the angle between the third insert protuberance side surface ( 68 ) and the bisector (B) is equal to half the protuberance wedge angle ( 2 α).