Cutting insert

A cutting tool (10) having a longitudinal axis of rotation (A) and comprising:

• a tool body (16) having at least one insert pocket (24) formed in a front end (18) of the tool body and a cutting insert (22) retained in the at least one insert pocket, the at least one insert pocket comprising:
• a pocket tangential abutment surface (96);
• a threaded bore (98) extending tangentially rearwardly from the pocket tangential abutment surface;
• pocket side walls (100) extending upwardly from the pocket tangential abutment surface, two of the pocket side walls are a first pocket abutment surface (102) and a second pocket abutment surface (106), each of which forms a pocket internal angle (θ) with the pocket tangential abutment surface;
• the cutting insert (22) has a polygonal prismatic shape with two opposing end surfaces (28) and a peripheral surface (34) extending therebetween, a median plane (M) is located between the end surfaces bisecting the cutting insert, the peripheral surface has a plurality of polygonal sides (48), each polygonal side has a side abutment surface (38) and merges with an adjacent polygonal side through a rounded corner (40), each rounded corner forms a vertex (42) of the polygonal shape, the cutting insert comprising:
• a through bore (36) extending between the end surfaces;
• an insert tangential abutment surface (44) extending around the through bore;
• a cutting region (46) associated with each of the polygonal sides (48), the cutting region being elevated with respect to the insert tangential abutment surface (44) and comprising:
• a primary cutting edge (50), associated with a polygonal side (48), formed at an intersection of a primary rake surface (54) and a primary relief surface (56);
• a secondary cutting edge (52), associated with a rounded corner (40), formed at an intersection of a secondary rake surface (72) and a secondary relief surface (74), and merging with the primary cutting edge (50);
• the primary cutting edge (50) comprises three primary cutting edge portions as seen in a side view of the cutting insert:
• a substantially straight first primary central portion (62) that is slanted with respect to the median plane;
• a convex second primary portion (64) that merges with the first primary central portion (62) at an upper end (66) of the first primary central portion;
• a concave third primary portion (68) that merges with the first primary central portion (62) at a lower end (70) of the first primary central portion;
• the secondary cutting edge (52) comprises three secondary cutting edge portions as seen in a side view of the cutting insert:
• a substantially straight first secondary central portion (82) that is slanted with respect to the median plane, the first primary and secondary central portions slanting in different directions;
• a convex second secondary portion (84) that merges with the first secondary central portion (82) at an upper end (86) of the first secondary central portion;
• a concave third secondary portion (88) that merges with the first secondary central portion (82) at a lower end (90) of the first secondary central portion;
• the primary relief surface (56) forms a primary relief surface angle (γ) with an associated side abutment surface (38), the primary relief surface angle varies from a primary first maximal value adjacent a primary edge upper end (58) to a primary second minimal value adjacent a primary edge lower end (60);
• the secondary relief surface (74) forms a secondary relief surface angle (δ) with an associated rounded corner (40), the secondary relief surface angle varies from a secondary first maximal value adjacent a secondary edge upper end (76) to a secondary second minimal value adjacent a secondary edge lower end (78);
• wherein
• the insert tangential abutment surface (44) abuts the pocket tangential abutment surface (96),
• a first side abutment surface (38) of the cutting insert abuts the first pocket abutment surface (102),
• a second side abutment surface (38) of the cutting insert abuts the second pocket abutment surface (106), and
• a clamping bolt (26) passes through the through bore (36) of the cutting insert and threadingly engages the threaded bore (98).

A reversible, generally pentagonal-shaped cutting insert (22) comprising:

• two opposing end surfaces (28);
• a through bore (36) having a through bore axis (B) extending between the end surfaces;
• an insert tangential abutment surface (44) extending around the through bore on both end surfaces;
• an imaginary median plane (M) located between the end surfaces and bisecting the cutting insert;
• a peripheral surface (34) extending between the end surfaces and having five sides (48), each side having a side abutment surface (38) and merging with an adjacent side through a rounded corner (40);
• and
• a cutting region (46) associated with each side (48), each cutting region being elevated with respect to the insert tangential abutment surface (44) and comprising:
• a primary cutting edge (50) associated with a side (48), formed at an intersection of a primary rake surface (54) and a primary relief surface (56), and extending towards the median plane (M) from a primary edge upper end (58) to a primary edge lower end (60);
• and
• a secondary cutting edge (52) associated with a rounded corner (40), formed at an intersection of a secondary rake surface (72) and a secondary relief surface (74), and extending towards the median plane from a secondary edge upper end (76) to a secondary edge lower end (78);
• wherein:
• the secondary edge upper end (76) merges with the primary edge upper end (58);
• a secondary edge lower end (78) merges with the primary edge lower end (60) of the primary cutting edge (50) of a preceding cutting region (46);
• each rounded corner (40) forms a vertex (42) of the generally pentagonal shape;
• the secondary edge lower end (78) and the primary edge lower end (60) are spaced apart from a corresponding associated vertex (42);
• the primary relief surface (56) forms a primary relief surface angle (γ) with an associated side abutment surface (38), the primary relief surface angle (γ) varying from a primary first maximal value adjacent the primary edge upper end (58) to a primary second minimal value adjacent the primary edge lower end (60);
• and
• the secondary relief surface (74) forms a secondary relief surface angle (δ) with an associated rounded corner (40), the secondary relief surface angle (δ) varying from a secondary first maximal value adjacent the secondary edge upper end (76) to a secondary second minimal value adjacent the secondary edge lower end (78).