Insert clamping mechanism of indexable grooving tool and clamping tool

An insert clamping mechanism of an indexable grooving tool, the insert clamping mechanism comprising:

• an insert holding plate portion which is provided in a tool main body;
• an insert mounting seat which penetrates the insert holding plate portion in a thickness direction of the insert holding plate portion, extends in a slit shape, and is configured for a grooving cutting insert having a cutting edge to be mounted detachably, one end portion of both end portions of the insert mounting seat along an extending direction being open on an end surface of the insert holding plate portion;
• an opening-closing operation slit which is formed into a slit shape penetrating the insert holding plate portion in the thickness direction and communicates with the other end portion of the both end portions of the insert mounting seat along the extending direction;
• and
• a clamping tool which is configured to be inserted into the opening-closing operation slit,
• wherein an upper wall and a lower wall disposed to face each other in a separated manner are formed in the opening-closing operation slit,
• wherein the insert holding plate portion is configured to be elastically deformable such that the upper wall and the lower wall are separated from each other,
• wherein the clamping tool has a shaft portion configured to be inserted between the upper wall and the lower wall, and
• wherein in a cross-sectional view perpendicular to a center axis of the shaft portion,
• the shaft portion has a major axis and a minor axis orthogonal to each other on the center axis,
• an outer diameter of the shaft portion in a minor axis direction is less than a distance between the upper wall and the lower wall through the center axis along a vertical direction in which the upper wall and the lower wall face each other, and an outer diameter of the shaft portion in a major axis direction is more than the distance,
• at least one end portion of the both end portions positioned on the major axis in an outer circumference of the shaft portion is formed into a recessed shape or a linear shape and is disposed not to come into contact with the upper wall and the lower wall, and
• support portions having a largest outer diameter in the shaft portion are respectively formed in parts adjacent to the end portions on both sides around the center axis along the shaft portion.