Cutting tool having an indexable cutting insert retained by a moment force about a pivot axis

An insert holder (22) having holder axis (A1) establishing a forward-to-rearward direction (DF, DR), and comprising:

• a holder shank (22) extending along the holder axis (A1);
• and
• a holder head (26) formed at a forward end of the holder shank (26), the holder head comprising:
• spaced apart lower and upper clamping portions (30, 32) located on opposite sides of a horizontal first plane (P1) containing the holder axis (A1), the upper clamping portion (32) being displaceable relative to the lower clamping portion (30);
• a pivot axis (A2) extending through the lower clamping portion (30) in a direction parallel to the horizontal first plane (P1);
• first and second lower clamping surfaces (34, 36) formed on the lower clamping portion (30) and spaced apart from one another along the pivot axis (A2) by a transitional surface (35) which is recessed relative to the first and second lower clamping surfaces (34, 36);
• a vertical second plane (P2) extending along the holder axis (H1), perpendicular to the horizontal first plane (P1) and located between the first and second lower clamping surfaces (34, 36);
• an upper clamping surface (38) provided on the upper clamping portion (32) and facing a first direction, the upper clamping surface (38) intersected by the vertical second plane (P2) and entirely located between the first and second lower clamping surfaces (34, 36) in a lateral direction (dL) perpendicular to the second plane (P2);
• and
• a stopper portion (64) formed on the holder head (26), the stopper portion (64) having a stopper surface (66) facing a second direction different from the first direction faced by the upper clamping surface (38), wherein:
• in cross-sections taken in fifth and sixth planes (P5, P6) parallel to the second plane (P2) and intersecting the spaced apart first and second lower clamping surfaces (34, 36), respectively, the first and second lower clamping surfaces (34, 36) are convex.

A cutting tool (20) comprising an insert holder (22) and an indexable cutting insert (24) removably secured therein,

• the insert holder (22) comprising:
• a holder head (26) and a holder shank (28) extending rearwardly therefrom along a holder axis (A1),
• the holder head (26) having spaced apart lower and upper clamping portions (30, 32) located on opposite sides of a first plane (P1) containing the holder axis (A1), and further having a stopper portion (64),
• the lower clamping portion (30) extending along a pivot axis (A2) and having spaced apart first and second lower clamping surfaces (34, 36) located on opposite sides of a second plane (P2) perpendicular to the first plane (P1),
• the upper clamping portion (32) being displaceable relative to the lower clamping portion (30) and having an upper clamping surface (38) which is intersected by the second plane (P2),
• the stopper portion (64) being non-displaceable relative to the lower clamping portion (30) and having a stopper surface (66);
• the cutting insert (24) comprising:
• opposing first and second end surfaces (40, 42) with a peripheral surface (44) extending therebetween and an insert axis (A3) extending therethrough,
• the peripheral surface (44) having a plurality of cutting portions (48) circumferentially spaced apart about the insert axis (A3), one of the plurality of cutting portions (48) being an operative first cutting portion (48′) having an operative first cutting edge (50′) formed at the intersection of a first rake surface (52′) and a first relief surface (54′), the first rake surface (52′) facing in a first direction (d1) about the insert axis (A3),
• wherein:
• the upper clamping surface (38) makes contact with a first leading abutment surface (68a) which is formed on a first abutment portion (56′) of the peripheral surface (44), the first leading abutment surface (68a) facing in said first direction (d1) about the insert axis (A3),
• the stopper surface (66) makes contact with a first trailing abutment surface (68b) which also is formed on the first abutment portion (56′) of the peripheral surface (44), the first trailing abutment surface (68b) facing in a second direction (d2) about the insert axis (A3) rotationally opposite to said first direction (d1),
• a second abutment portion (56″) of the peripheral surface (44) makes contact with the first and second lower clamping surfaces (34, 36),
• the second plane (P2) intersects the plurality of cutting portions (48),
• each cutting portion (48) has a cutting edge (50),
• in a cross-section taken in a fourth plane (P4) coincident with or parallel to the second plane (P2), the plurality of cutting edges (50) define a first imaginary circle (C1) which circumscribes the peripheral surface (44),
• the cutting insert (24) has a maximum width (WMAX) in a direction parallel to the insert axis (A3), and
• the maximum width (WMAX) is greater than a first radius (R1) of the first imaginary circle (C1).