Rotating-cutting-edge-type milling tool and cutting method using same

A rotating-cutting-edge-type milling tool comprising:

• a tool main body which is rotated around a tool axial line;
• an insert attachment seat formed at an outer periphery portion of a distal end of the tool main body;
• and
• a cutting insert formed in a discoid shape is rotatable on a shaft around an insert axial line thereof, the shaft mounted on the insert attachment seat, the cutting insert including:
• front and rear surfaces which intersect the insert axial line;
• an outer periphery surface which connects circumferential edges of the front and rear surfaces;
• and
• a cutting edge formed in a circular shape extending around the insert axial line, which is formed on a circumferential edge of the front surface, wherein
• among the front and rear surfaces, the front surface is located to face forward in a tool rotation direction of the tool main body around the tool axial line, and the rear surface is located to face rearward in the tool rotation direction and sits on the insert attachment seat,
• a virtual circle is obtained by a locus of a tool distal end edge of the cutting edge in a direction of the tool axial line when the tool distal end edge is rotated in a tool circumferential direction of the tool main body around the tool axial line,
• a virtual plane as a reference plane is obtained by a locus of a tangent line of the virtual circle, which passes through the tool distal end edge, when the tangent line is moved parallel to the tool axial line toward a tool posterior end of the tool main body from the tool distal end edge,
• an angle (ARt) at which a cross line of the reference plane and a cutting edge virtual plane including the cutting edge, is inclined with respect to the tool axial line projected onto the reference plane, is in a range of −30 degrees to −60 degrees,
• an angle (RR) at which a cutting edge tangent line of the cutting edge which passes through the tool distal end edge and extends outward, is inclined with respect to a predetermined tool radial direction orthogonal to the tool axial line, which passes through the tool distal end edge and extends outward, is in a range of −30 degrees to −75 degrees or is in a range of −20 degrees to 30 degrees, and
• the ranges of the angle (ARt) and the angle (RR) cause the insert axial line and a direction of a resultant force on the insert to be substantially parallel to each other during a cutting operation.