Numerical control system of machine tool

A numerical control system of a machine tool, the numerical control system comprising:

• a command unit;
• and
• a control unit that controls a drive unit of respective axes of the machine tool in accordance with a command from the command unit,
• the command unit comprising:
• an interpolation block waveform drawing unit that performs a simulation of an NC program, calculates an interpolation pulse of a relationship between speed and time or a relationship between position and time indicating an operation of the respective axes from a command value of an axis address of the respective axes, and sequentially outputs an interpolation command of the respective axes for each block to draw a waveform of the relationship between speed and time or the relationship between position and time in a case of operating the machine tool;
• a different axis block specifying unit that compares two blocks adjacent in time series which are drawn by the interpolation block waveform drawing unit, and specifies the two adjacent blocks calculated from command values of different axis addresses;
• and
• an interpolation overlap block waveform creating unit that obtains an overlappable amount of the two adjacent blocks specified by the different axis block specifying unit, and overlaps the two adjacent blocks specified by the different axis block specifying unit on a basis of the overlappable amount to create a waveform of the relationship between speed and time or the relationship between position and time in a case of operating the machine tool.