Patent claim: A turning insert 1 comprising a top surface 8 an opposite bottom surface 9 side surfaces 13 13 13 connecting the top surface 8 and the bottom surface 9 a reference plane RP located parallel to and between the top surface 8 and the bottom surface 9 a center axis A1 extending perpendicular to the reference plane RP and intersecting the reference plane RP three nose portions 15 15 15 formed symmetrically around the center axis A1 each nose portion 15 15 15 comprising a first cutting edge 11 11 11a second cutting edge 12 12 12 and a convex nose cutting edge 10 10 10 connecting the first 11 11 11and second 12 12 12 cutting edges characterized in that in a top view the first 11 and second 12 cutting edges on the same nose portion 15 forms a nose angleof 2550 relative to each other and wherein the distance from the first cutting edge 11 to the reference plane RP decreases at increasing distance from the nose cutting edge 10.

Related passage: In Fig.3 an enlarged cutting comer is shown which engages a work piece the thread 23 of which is dashed.The cutting edge consists of a number of segments and includes an active major cutting edge 24 a nose edge 25 an active minor cutting edge 24A a passive edge 26 and a topping edge 27.The cutting tip 18 of the cutting corner projects a distance L1 measured from a line touching the topping surface 27 and the extreme points of the nose edge 25.The bisector B is defined by the major cutting edge the nose edge and minor cutting edge wherein the major cutting edge is provided on one side of the bisector and the minor cutting edge on the other side of the bisector while the nose edge cutting intersects the bisector.The major cutting edge 24 forms an acute angleof about 25 to 30 with the bisector B.The major cutting edge softly connects to the nose edge 25 which substantially is defined by an radius r of about 005 to 15 mm.The nose edge further softly connects preferably to the active minor cutting edge 24A or directly to the passive cutting edge 26.The minor cutting edge connects to the passive cutting edge on the perpendicular distance L2 from a tangent T of the nose edge in the extreme points of the nose edge.The distance L2 is bigger than or the same as the maximum depth of infeed per pass but less than the half of the distance L1 and preferably less than 25 mm and is preferably of the size of the radius r.Also the minor cutting edge or the part of the nose edge which is closest to the passive cutting edge forms the anglewith the bisector.The passive cutting edge 26 forms an anglewith the bisector which is 4 to 8 preferably about 5 less than the angle.The passive cutting edge connects to the topping edge 27 via a concave substantially passive curved edge 28 defined by a radius R the size of which depends of the actual thread profile but the radius is bigger than the radius of the nose edge.The cutting tip thus has a passive edge 26 which at least partly is provided on one side of an imaginary line S parallel with the direction of infeed F for the cutting insert and touching the cutting tip 18 said side facing away from the connected thread flank 23.The line S touches the nose edge 25 as well as intersects the curved cutting edge 28.