Numerical control device, machine learning device, and numerical control method

A numerical control device comprising:

• control computation circuitry to control a spindle that is a rotation axis of a machining target,
• first drive shaft to drive a first tool to perform vibration cutting machining on the machining target, and
• second drive shaft to drive a second tool to perform vibration cutting machining on the machining target,
• wherein:
• the control computation circuitry comprises:
• a memory to store a machining program for performing vibration cutting machining on the machining target;
• determination circuitry to determine whether the numbers of vibrations of the first drive shaft and the second drive shaft follow a first spindle rotation speed that is a rotation speed of the spindle specified by the machining program;
• and
• number-of-vibrations calculation circuitry to, in response to the determination circuitry determining that the number of vibrations of the first drive shaft follows the first spindle rotation speed and the number of vibrations of the second drive shaft does not follow the first spindle rotation speed, change the rotation speed of the spindle from the first spindle rotation speed to a third spindle rotation speed,
• the third spindle rotation speed has a value between the first spindle rotation speed and a second spindle rotation speed, and
• the second spindle rotation speed is calculated on the basis of:
• a first vibrational frequency calculated based on the first spindle rotation speed and the number of vibrations of the first drive shaft;
• and the number of vibrations of the second drive shaft.