Rotationally asymmetric double-ended grooving cutting insert, insert holder and cutting tool

An insert holder (24) comprising a clamping portion (68) comprising:

• opposing first and second clamping portion side surfaces (70a, 70b) and a clamping portion front end surface (72) extending therebetween;
• a lower base jaw (80) and an opposing upper clamping jaw (78) which is resiliently displaceable relative to the lower base jaw (80);
• and
• an insert receiving slot (26) being longitudinally elongated in a direction defining a slot longitudinal axis (C) and opening out to the clamping portion front end surface (72) forming a front slot opening (74), the insert receiving slot (26) being formed from a gap between the lower base jaw (80) and the upper clamping jaw (78) and delimited by:
• a slot peripheral wall surface (76) comprising:
• a clamping jaw surface (82), a base jaw lower surface (84) and a slot rear surface (86) extending therebetween, the clamping jaw surface (82) being formed on the upper clamping jaw (78) and the base jaw lower surface (84) being formed on the lower base jaw (80);
• upper and lower slot engagement ridges (92a, 92b) which project from the clamping jaw surface (82) and base jaw lower surface (84) respectively;
• wherein:
• the upper and lower slot engagement ridges (92a, 92b) extend along upper and lower ridge longitudinal axes (RU, RL), respectively, which converge towards each other in a direction from the clamping portion front end surface (72) towards the slot rear surface (86) defining an acute ridge wedge angle (6);
• the insert receiving slot (26) has a slot vertical axis (V) oriented perpendicular to the slot longitudinal axis (C) and intersecting therewith, the slot vertical axis (V) extending through the clamping jaw surface (82) and the base jaw lower surface (84);
• characterized in that:
• the slot rear surface (86) comprises a slot rear stopper surface (88) and a slot rear recessed surface (90) which are oriented differently to each other, the slot rear stopper surface (88) being closer to the first clamping portion side surfaces (70a) than the slot rear recessed surface (90) and the slot rear recessed surface (90) being closer to the second clamping portion side surfaces (70b) than the slot rear stopper surface (88);
• and
• the slot rear recessed surface (90) overlaps with the slot rear stopper surface (88) in a direction along the slot vertical axis (V) and is further from the front slot opening (74) in a direction along the slot longitudinal axis (C) than the slot rear stopper surface (88).

A double-ended cutting insert (22) comprising:

• opposing first and second relief face surfaces (28a, 28b) and an insert peripheral surface (30) extending therebetween about an insert longitudinal axis (A), the insert peripheral surface (30) comprising opposing first rake and support face surfaces (34a, 36a) and opposing second rake and support face surfaces (34b, 36b) which all connect the first and second relief face surfaces (28a, 28b);
• a first insert central axis (C1) oriented perpendicular to the insert longitudinal axis (A) and extending through the first rake and support face surface (34a, 36a);
• a second insert central axis (C2) oriented perpendicular to both the first insert central axis (C1) and the insert longitudinal axis (A), and extending through the second rake and support face surface (34b, 36b),
• first and second cutting edges (44a, 44b) formed at the intersection of the first and second relief face surfaces (28a, 28b) and the first and second rake face surfaces (34a, 34b), respectively;
• first rake and support engagement grooves (48a, 50a) which are recessed in the first rake and support face surfaces (34a, 36a), respectively, and which open out to at least the second relief face surface (28a);
• and
• second rake and support engagement grooves (48b, 50b) which are recessed in the second rake and support face surfaces (34b, 36b), respectively, and which open out to at least the first relief face surface (28b);
• wherein:
• the cutting insert (22) lacks 180° rotational symmetry about all three of the insert longitudinal axis (A), the first insert central axis (C1) and the second insert central axis (C2);
• for at least one-half its length, the first support engagement groove (50a) is mirror symmetric about a first insert bisector plane (B1) which contains the insert longitudinal axis (A) and the first insert central axis (C1);
• and
• for at least one-half its length, the second support engagement groove (50b) is mirror symmetric about a second insert bisector plane (B2) which contains the insert longitudinal axis (A) and the second insert central axis (C2).