A numerical control apparatus includes: a drive unit controlling a main shaft rotating a workpiece, a first drive shaft feeding a cutting tool relatively to the workpiece along a perpendicular direction to a lead direction of a thread, and a second drive shaft feeding the cutting tool relatively to the workpiece along the lead direction; and a vibration unit superimposing, on movement of the first drive shaft, vibration having a period having a predetermined ratio with a rotation period of the main shaft, and forms a thread on the workpiece by moving the cutting tool and the workpiece relative to each other and performing cut processes on the workpiece. The numerical control apparatus includes a thread-cutting vibration adjustment unit controlling the drive unit to shift phase of the vibration with respect to phase of the main shaft by a predetermined vibration phase shift amount every time in the cut processes.

Provided is a numerical value control device capable of easily setting an effective diameter for a machined circle. The numerical value control device is equipped with a command unit which prescribes a machined circle standard or a proportion of the tolerance class to the machined circle tolerance in a machining program for machining a circle using a machine tool, and also equipped with a setting unit for setting a correction amount for the effective diameter of the machined circle on the basis of the machined circle standard or the proportion of the tolerance class to the machined circle tolerance.

Embodiments of present disclosure relate to thread machining apparatus (300), method and system. The thread machining apparatus (300) comprises: a spindle motor (310) adapted to drive a thread tool (200) coupled to an output shaft of the spindle motor (310) to rotate at a rotational speed; and a feeding device (320) movably coupled to the spindle motor (310), and configured to drive the spindle motor (310) to move along an axial direction (X) of the spindle motor (310) at a moving speed; wherein during thread machining, the moving speed is proportional to the rotational speed. The solutions of the embodiments of present disclosure have significantly improved the efficiency, stability and accuracy of thread machining.

A numerical controller is configured to move a tool in synchronism with rotation of a workpiece, thereby controlling a machine tool configured to perform thread cutting, and comprises a cutting amount variation setting unit for previously setting the size of a variation of a cutting amount during the thread cutting. The cutting amount variation setting unit periodically changes the cutting amount based on a preset variation during the thread cutting.

A machine tool includes a number-of-same-rotation-speed-cutting-passes computing section that decides the number of same rotation speed cutting passes. The number-of-same-rotation-speed-cutting-passes computing section determines the cutting mode of a threading process based on a set machining program etc., and automatically decides an optimal number of same rotation speed cutting passes according to the cutting mode. Thus, even unskilled operators can easily suppress chatter vibrations, and can easily use the machine tool.

Provided is a technology capable of reliably carrying out air cutting during oscillation machining for threading regardless of oscillation phase differences. This machine tool control device 1 comprises: a condition acquisition unit 11 for acquiring, as a precondition, one or two pieces of information among three pieces of information, namely, an oscillation phase difference, information regarding a workpiece radial cut depth, and information regarding a radial oscillation amplitude of the workpiece; an air cut amount acquisition unit 12 for acquiring a specified air cut amount indicating the degree of air cut in the oscillation direction; and a machining control unit 13 for determining (a) piece(s) of information not acquired by the condition acquisition unit 11 among the three pieces of information on the basis of the precondition and carrying out machining control such that an air cut amount based on the interval between the n-th threading path and a threading path subsequent to the n-th path matches the specified air cut amount.