Tool body, insert support mechanism and cutting tool

A cutting tool (1) in which a cutting insert (10) is removably mounted on an insert mounting part (21) of a tool body (20), the cutting tool having an insert support mechanism configured to receive a rotational moment which acts on the cutting insert (10) so as to rotate the cutting insert (10) on a base surface (21A) of the insert mounting part (21), wherein:

• the cutting insert (10) comprises a first engagement part (14) provided in an end surface (12) which is brought into contact with the base surface (21A), the first engagement part (14) including at least two specific portions (15) which are separate from each other;
• the base surface (21A) of the tool body (20) is provided with second and third engagement parts (24, 25) so as to be separate from each other, the second and third engagement parts (24, 25) corresponding to the two specific portions (15);
• when the cutting insert (10) is mounted on the insert mounting part (21), one of the specific portions (15) is brought into contact with the second engagement part (24) while the other one of the specific portions (15) does not come into contact with the third engagement part (25);
• and
• when the cutting insert (10) receives the rotational moment, at least part of the insert mounting part (21) is elastically deformed, so that the other one of the specific portions (15) is brought into contact with the third engagement part (25).

A tool body (20) having a rotational axis (C), a leading end surface (30), an outer side surface (32) extending from the leading end surface (30) to a base end surface (31), and an insert mounting part (21) opening to at least one of the leading end surface (30) and the outer side surface (32), wherein:

• the insert mounting part comprises:
• a base surface (21A) extending in a virtual plane;
• a side wall surface (21B);
• a screw hole (23) formed in the base surface, the screw hole having a central axis (H) which intersects the virtual plane at a center point (X);
• and
• second and third engagement parts (24, 25) formed on the base surface (21A);
• when, viewed from a direction facing the base surface (21A), the base surface (21A) is divided into four areas (26, 27, 28, 29) by a first boundary (L1) which is parallel to the rotational axis (C) and passes through the center point (X), and a second boundary (L2) which is perpendicular to the first boundary (L1) and also passes though the center point (X);
• the second engagement part (24) is formed in the first area (26) on the outer side surface (32) side relative to the first boundary (L1) and on the base end surface (31) side relative to the second boundary (L2);
• the third engagement part (25) is formed in the second area (27) on the outer side surface (32) side relative to the first boundary (L1) and on the leading end surface (30) side relative to the second boundary (L2);
• and
• when viewed from the direction facing the base surface (21A), a first distance (A) between the second engagement part (24) and the center point (X) is greater than a second distance (B) between the third engagement part (25) and the center point (X).