Numerical value controller

A numerical value controller for a machine tool, the numerical value controller comprising:

• a memory that stores a machining program for drilling a hole in a workpiece in accordance with relative movement between a tool and the workpiece in a depth direction extending along a longitudinal axis of the tool;
• and
• a processor configured to control the relative movement between the tool and the workpiece based on the machining program and move the tool relative to the workpiece in the depth direction from a return point to a hole bottom point,
• wherein the return point is a position retracted in the depth direction from a workpiece surface where the tool starts to perform a drilling process,
• wherein the machining program includes a command for a workpiece height point serving as a position of the workpiece surface in the depth direction,
• wherein the processor is configured to:
• move, from the return point to an intermediate position between the return point and the workpiece height point, the tool relative to the workpiece in the depth direction at a rapid traverse rate higher than a cutting feed rate;
• and
• change, at the intermediate position, a relative rate of the tool relative to the work piece in the depth direction from the rapid traverse rate to the cutting feed rate, and
• wherein the intermediate position is determined according to a responsiveness of mechanical control of the machine tool.