Machining tool

A machining tool for performing cutting operation on an inner periphery of a workpiece including an opening to form a plurality of machined surfaces, the machining tool comprising:

• a tool body configured to be driven to rotate around an axis line;
• a plurality of cutting tools configured to rotate together with the tool body;
• a cartridge configured to be attached to the tool body so as to advance and retreat along the axis line;
• and
• a cam configured to come into contact with a proximal end surface of the cartridge to thereby cause the cartridge to advance and retreat,
• at least one of the plurality of cutting tools being attached to the cartridge;
• wherein
• the cam has a circular arc surface extending along an outer circumference of a circular arc and a cut surface formed by cutting off a segment of the circular arc, and the cam is configured to rotate around a center of the circular arc as a center of rotation so that the circular arc surface and the cut surface are selectively brought into contact with the proximal end surface of the cartridge,
• the cartridge is advanced when the circular arc surface comes in contact with the proximal end surface, and
• the cartridge is retreated when the cut surface comes in contact with the proximal end surface.