Numerical control device

A numerical control device that controls a machine tool that includes an X-axis for moving a turret to which a tool is attached, an H-axis for rotating the turret, and a C-axis for rotating a workpiece and that does not have a Y-axis orthogonal to the X-axis, the numerical control device comprising:

• an analyzer that analyzes a virtual-Y-axis rapid-traverse command in a virtual-Y-axis interpolation mode in which an X-Y-axis movement command in a machining program is converted into a command in an X-H-C coordinate system, an analysis result of the converted command is interpolated, and the X-axis, the H-axis, and the C-axis are cooperatively driven;
• a C-axis interpolation processor that interpolates a C-axis angle in response to the analyzed virtual-Y-axis rapid-traverse command;
• and
• an X-axis interpolation processor that interpolates an X-axis position based on the interpolated C-axis angle, wherein
• the numerical control device controls an X-axis position so as to rotate the C-axis while keeping a C-axis velocity to a constant velocity and to enable a virtual Y-axis to move substantially linearly.