Turning tool

A turning tool comprising:

• a replaceable cutting insert;
• and a tool body that secures the cutting insert, wherein
• the cutting insert is mirror-image symmetric with respect to a first symmetric surface which is perpendicular to a central axis of a mounting hole, and is mirror-image symmetric with respect to a second symmetric surface which extends along the central axis,
• the cutting insert has a front surface, a rear surface which is on an opposite side to the front surface, a peripheral side surface which connects the front surface and the rear surface, and the mounting hole which penetrates the front surface and the rear surface, and
• the peripheral side surface is formed parallel with the central axis, and
• the peripheral side surface includes:
• a first cutting part constituted of a first cutting edge which is parallel with the central axis, and a first rake surface and a first flank which is adjacent to the first cutting edge;
• a second cutting part constituted of a second cutting edge which is mirror-image symmetric with the first cutting part with respect to the second symmetric surface and is parallel with the central axis, and a second rake surface and a second flank which is adjacent to the second cutting edge;
• a base end part which is on the opposite side to a leading end part where the first cutting part and the second cutting part are disposed;
• a third flat surface which continues from the first rake surface;
• a first flat surface which extends towards the third flat surface from one end of the base end part;
• a fourth flat surface which is mirror-image symmetric with the third flat surface with respect to the second symmetric surface and continues to the second rake surface;
• and
• a second flat surface which is mirror-image symmetric with the first flat surface with respect to the second symmetric surface and extends towards the fourth flat surface from the other end of the base end part,
• wherein a boundary portion between the third flat surface and first flat surface is non-planar,
• wherein a boundary portion between the fourth flat surface and second flat surface is non-planar,
• the tool body includes:
• an insert mounting seat which secures the cutting insert in an orientation in which the second flat surface is parallel with a longitudinal direction of the tool body, in a state where the first cutting part is usable;
• and
• a first discharge port which supplies coolant to the first cutting edge from the first rake surface side, in a state where the first cutting part is usable, and
• the first discharge port is disposed between the second flat surface and a first reference surface which is parallel with the second flat surface and extends along an edge line of the first cutting edge.