Method and apparatus for applying vibration and machining an object

A numerical control device that controls a drive unit including drive axes for machining a machining object by moving a tool and the machining object relative to each other along a movement path while applying vibration, by use of the drive axes provided for the tool or the machining object,

• wherein a rotational speed of a main shaft that rotates the machining object when performing the machining and a number of vibrations of the vibration to be applied during each one rotation of the main shaft are determined based on a predetermined frequency selected from a plurality of preset frequencies of the vibration to be applied,
• the numerical control device comprising:
• a memory to store data that identifies a plurality of specific frequencies of the vibration for the respective drive axes which are related to the vibration to be applied, which are to be avoided due to one or more resonance frequencies or anti-resonance frequencies of the rotation axes, from among a plurality of preset frequencies of the vibration to be applied;
• and
• a controller configured to, based on the plurality of frequency data, change:
• i) the rotational speed of the main shaft or ii) the number of applied vibrations, wherein the change is based on:
• a) a commanded rotational speed of the main shaft for rotating the machining object, b) a given number of applied vibrations of the applied vibration in each one rotation of the main shaft, and c) a process period for forming a movement command to the drive axes, so that a frequency of the vibration to be applied becomes a frequency that is different from the specific frequencies stored in the memory.