Detachable insert type cutting tool

A holder for a detachable insert type cutting tool comprising:

• a holder main body;
• an insert mounting seat which is provided in the holder main body and on which a cutting insert having a cutting edge is detachably mounted;
• and
• an upper jaw section and a lower jaw section for pinching and fixing the cutting insert,
• wherein the insert mounting seat is provided between the lower surface of the upper jaw section and the upper surface of the lower jaw section,
• convex curve outer surfaces are formed on one side of the upper and lower jaw sections when viewed from the leading end sides of the upper and lower jaw sections,
• concave curve inner surfaces are formed on the other side of the upper and lower jaw sections, and
• the concave curve inner surface of the upper jaw section is disposed at a position retreated further radially outward than an arc surface extending along the concave curve inner surface of the lower jaw section in a state where the cutting insert is fixed to the insert mounting seat.

A head member for a detachable insert type cutting tool comprising:

• an insert mounting seat on which a cutting insert having a cutting edge is detachably mounted;
• and
• an upper jaw section and a lower jaw section for pinching and fixing the cutting insert,
• wherein the insert mounting seat is provided between the lower surface of the upper jaw section and the upper surface of the lower jaw section,
• convex curve outer surfaces are formed on one side of the upper and lower jaw sections when viewed from the leading end sides of the upper and lower jaw sections,
• concave curve inner surfaces are formed on the other side of the upper and lower jaw sections, and
• the concave curve inner surface of the upper jaw section is disposed at a position retreated further radially outward than an arc surface extending along the concave curve inner surface of the lower jaw section in a state where the cutting insert is fixed to the insert mounting seat.