A numerical control apparatus includes: a thread-whirling motor controller controlling, based on a thread lead representing a movement amount of a thread whirling tool per rotation of a workpiece, a reference differential speed representing a difference between a predetermined reference rotational speed of the thread whirling tool and a rotational speed of the workpiece, the number of tool blades of the thread whirling tool, and a workpiece spindle speed representing the rotational speed of the workpiece, a first motor moving the thread whirling tool, a second motor rotating the thread whirling tool, and a third motor rotating the workpiece. The thread-whirling motor controller controls: the first motor based on the thread lead and the reference differential speed; the second motor based on the thread lead, the reference differential speed, the number of tool blades, and the workpiece spindle speed; and the third motor based on the workpiece spindle speed.

A numerical controller includes a motion start point determination unit that calculates a cycle motion start point where the screw thread cutting cycle is to be started, an acceleration/deceleration control unit that moves the tool from the cycle motion start point to a screw thread cutting start point with motions of a plurality of axes overlapped, and a control unit that controls motions of a machining device based on control instructions received from an instruction analysis unit and the acceleration/deceleration control unit. The cycle motion start point is a point from which acceleration or deceleration of a first axis and a second axis orthogonal to the first axis is started so as to make a speed of the first axis reach a specified cutting feed speed and to make a speed of the second axis substantially become zero at time of arrival at the screw thread cutting start point.

An automatic lathe includes a main spindle that rotates a workpiece about a shaft center, a cutting tool that processes the workpiece, a feeder that moves the cutting tool, an input receiver that receives inputs regarding an eccentric distance and a radius, and a controller that controls the movement by the feeder such as to set a virtual circle having a radius of the distance, to set an offset virtual circle having a center at a position where a center of the virtual circle is offset from the shaft center of the workpiece in the radial direction of the workpiece by the radius, and to move the cutting tool along an circumference of the offset virtual circle in relation to a rotation of the workpiece by the main spindle. A hole is processed, which has the radius at a position away from the shaft center by the distance.

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.

To provide a controller for a machine tool capable of shredding chips in any thread cutting method. A controller for a machine tool comprises: an oscillation condition calculation unit that calculates an oscillation amplitude and an oscillation direction allowing shredding of chips occurring from lathe-turning machining based on an infeed amount in a radial direction of a work and a shift amount in a circumferential direction of the work relative to a last machining path of a tool used for the lathe-turning machining on the work; an oscillation command calculation unit that calculates an oscillation command for causing the work and the tool to oscillate relative to each other based on the oscillation amplitude and the oscillation direction calculated by the oscillation condition calculation unit; and an adder that adds a movement command for moving the work and the tool relative to each other for the lathe-turning machining on the work and the oscillation command.

To provide a controller for a machine tool capable of shredding chips and capable of performing machining by cutting correctly without implementation of a so-called finishing process. A controller for a machine tool includes: an oscillation command generation unit that generates an oscillation command for causing a work and a tool to oscillate relative to each other in a radial direction of the work based on a condition for oscillation; a movement command generation unit that generates a movement command for causing the work and the tool to move relative to each other for thread cutting of the work; an adder that adds the oscillation command and the movement command; and a determination unit that predetermines whether the oscillation command is to be added to the movement command, is which the adder outputs a superimposed command configured to include one or more types of machining patterns combining an arbitrary number of a total movement command with the oscillation command added, and an arbitrary number of a total movement command without the oscillation command added, in accordance with a result of determination by the determination unit.

A machine tool and a control device therefor, wherein vibration cutting of a workpiece is carried out by means of a tool and wherein, after the vibration cutting, finish-cutting is carried out for cutting a finishing allowance of the workpiece by means of the tool, without relative vibration between the workpiece and the tool, by relatively rotating the workpiece and the tool and relatively moving them in the feed direction. According to the invention, before the vibration cutting, a finishing allowance calculation means calculates a finishing allowance remaining on the workpiece after vibration cutting has been completed, and a determination means determines whether or not the finishing allowance as calculated by the finishing allowance calculation means is less than, or equal to a predetermined threshold value.

A numerical controller includes a motion start point determination unit that calculates a cycle motion start point where the screw thread cutting cycle is to be started, an acceleration/deceleration control unit that moves the tool from the cycle motion start point to a screw thread cutting start point with motions of a plurality of axes overlapped, and a control unit that controls motions of a machining device based on control instructions received from an instruction analysis unit and the acceleration/deceleration control unit. The cycle motion start point is a point from which acceleration or deceleration of a first axis and a second axis orthogonal to the first axis is started so as to make a speed of the first axis reach a specified cutting feed speed and to make a speed of the second axis substantially become zero at time of arrival at the screw thread cutting start point.

A controller for controlling a synchronized operation of spindle and feed axes. A spindle-axis control section includes an initial-motion control section for accelerating a spindle axis from a starting position; a maximum-acceleration detecting section for detecting a maximum acceleration of the spindle axis during acceleration; a residual rotation-amount detecting section for detecting a residual rotation amount of the spindle axis; a current-speed detecting section for detecting a current speed of the spindle axis; a decelerating-motion control section for decelerating the spindle axis to reach an intermediate speed, after the acceleration; a positioning-motion control section for decelerating the spindle axis to reach the target position after reaching the intermediate speed; and a torque-command limiting section for limiting a fluctuation of a torque command of the position control, instructed to the spindle axis, to a predetermined range over a period until a predetermined elapse condition is satisfied after reaching the intermediate speed.

An automatic lathe includes a main spindle that rotates a workpiece about a shaft center, a cutting tool that processes the workpiece, a feeder that moves the cutting tool, an input receiver that receives inputs regarding an eccentric distance and a radius, and a controller that controls the movement by the feeder such as to set a virtual circle having a radius of the distance, to set an offset virtual circle having a center at a position where a center of the virtual circle is offset from the shaft center of the workpiece in the radial direction of the workpiece by the radius, and to move the cutting tool along an circumference of the offset virtual circle in relation to a rotation of the workpiece by the main spindle. A hole is processed, which has the radius at a position away from the shaft center by the distance.