Workpiece machining apparatus

A workpiece machining apparatus comprising:

• a headstock to which a workpiece is attached when coordinate axes orthogonal to each other are set to a Z-axis and an X-axis;
• a tool rest being movable in the Z-axis direction and the X-axis direction;
• and
• a rotary tool unit attached to the tool rest,
• wherein the headstock has a support member being movable in the Z-axis direction, the support member has a spindle side contact portion in an end portion in the Z-axis direction,
• wherein the rotary tool unit has a tool body having a tool side contact portion with which the spindle side contact portion of the support member can come into contact in the Z-axis direction, and a tool protruding from the tool body and being rotatable around its own axis,
• wherein the tool which is rotating machines the workpiece by moving the tool body in the Z-axis direction in a state where the spindle side contact portion and the tool side contact portion are brought into contact with each other,
• wherein when a coordinate axis orthogonal to the Z-axis and the X-axis is set to a Y-axis, the tool protrudes from the tool body in the Y-axis direction,
• wherein the workpiece has a through-hole extending in the Z-axis direction,
• wherein the tool forms a groove extending in the Z-axis direction in the through-hole by moving the tool body inside the through-hole in the Z-axis direction, and
• wherein the spindle side contact portion and the tool side contact portion are engageable with each other in a state of being deviated from each other in the X-axis direction.