Tool body

A tool body to which a replaceable cutting insert is fixed, the tool body comprising:

• a holder:
• an insert mounting seat that is provided on a first surface of the holder;
• a clamp member that constrains the cutting insert placed on the insert mounting seat;
• and
• an operating member that presses a pressure receiving surface of the clamp member, wherein
• the clamp member has the pressure receiving surface, a spherical head portion that is formed into a spherical crown shape, and a hook portion that protrudes to a side opposite to a side of the spherical head portion when seen from a side of the first surface,
• the insert mounting seat supports the clamp member to be swingable with the spherical head portion as a fulcrum,
• the hook portion contacts a diameter reducing portion that is formed on an inner peripheral surface of a mounting hole for the cutting insert in a state in which the pressure receiving surface is pressed,
• the operating member has a screw portion on which a male screw threadedly engaged with the holder is formed and a pressing surface that presses the pressure receiving surface in a direction different than a direction at which an axial line of the screw portion extends,
• the pressure receiving surface is constituted by a part of a recessed cylindrical surface, and
• the pressing surface is constituted by a track formed by rotating a protruding arc serving as a generating line about the axial line of the screw portion on an outer peripheral side of the screw portion.