Milling cutter and cutting insert therefor

A cutting tool assembly comprising a cutting insert holder, a cutting insert and a clamping screw, the cutting insert holder comprising a clamping portion connected to a body portion;

• the clamping portion comprising:
• a lower clamping jaw having a lower peripheral surface and an upper clamping surface;
• an upper clamping jaw resiliently connected to the lower clamping jaw, the upper clamping jaw having a lower clamping surface and an upper peripheral surface;
• a through bore passing through the upper and lower clamping jaws, the through bore being threaded in one of the upper or lower clamping jaws;
• an insert receiving slot defined between the upper and lower clamping surfaces;
• the cutting insert comprising:
• an insert upper clamping surface bounded by an upper edge;
• an insert lower clamping surface bounded by a lower edge;
• a peripheral side surface between the insert upper clamping surface and the insert lower clamping surface;
• at least one cutting edge associated with the peripheral side surface;
• at least one through hole passing through the cutting insert between the insert upper and lower clamping surfaces;
• wherein:
• in a front view of the cutting tool assembly, the upper and lower clamping surfaces of the lower and upper clamping jaws, respectively, are partially convex, and the insert lower and upper clamping surfaces are concave;
• the cutting insert is retained in the insert receiving slot in a retained position by means of the clamping screw which passes through the through bore in the upper and lower clamping jaws of the cutting insert holder and through the at least one through hole in the cutting insert and is screwed into the threaded through bore in one of the upper or lower clamping jaws;
• the lower clamping surface of the upper clamping jaw engages the insert upper clamping surface at at least one upper region of contact and the upper clamping surface of the lower clamping jaw engages the insert lower surface at at least one lower region of contact;
• wherein:
• at least a portion of the insert upper clamping surface conforms with a portion of a first cylindrical surface having a first radius of curvature, r1, and a first cylinder axis;
• at least a portion of the insert lower clamping surface conforms with a portion of a second cylindrical surface having a second radius of curvature, r2, and a second cylinder axis;
• the upper clamping surface of the lower clamping jaw partially conforms with a third cylindrical surface having a third radius of curvature, R2, and a third cylinder axis;
• the lower clamping surface of the upper clamping jaw partially conforms with a fourth cylindrical surface having a fourth radius of curvature, R1, and a fourth cylinder axis;
• the fourth radius of curvature, R1, is greater than the first radius of curvature, r1, the third radius of curvature, R2, is greater than the second radius of curvature, r2.