A numerical control device for controlling multiple drive shafts that drive a tool for machining an object to be machined includes an analysis processing unit that analyzes a machining program, a machining path calculation unit that calculates a machining path, which is a travel path of the tool in cutting machining of the object to be machined, based on a result of analysis of the machining program performed by the analysis processing unit, and an interrupt pathway calculation unit that calculates a travel path of the tool in an interrupt operation based on the result of analysis. The interrupt operation is an operation repeatedly performed in which the tool is temporarily lifted up from the machining path while the tool is moved along the machining path and is machining the object to be machined.

To provide a control device for a machine tool capable of performing thread cutting while reducing the load on the machine tool from the oscillating operation, without extending the cycle time, and capable of reliably shredding chips in a case of performing the non-oscillating operation in the present pass after the oscillating operation in the previous pass. A control device for a machine tool includes: an oscillating operation execution determination unit that determines whether to execute an oscillating operation that causes the cutting tool to oscillate in the radial direction of the workpiece; an oscillation command generation unit that generates an oscillation command of the oscillating operation based on a determination result; a control unit that superimposes the oscillation command on a position command of the feed axis to generate a drive command. The oscillating operation execution determination unit determines to intermittently execute the oscillating operation, and the oscillation command generation unit generates an oscillation command so that a non-oscillating cutting portion of a present pass includes a portion at which oscillating cutting was performed in a previous pass, or so that an oscillating cutting portion of the present pass includes a portion at which non-oscillating cutting was performed in the previous pass.

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 control device for a machine tool and a machine tool capable of easily performing cutting with vibration according to the amount of feed is provided. The control device includes a control section for controlling the relative rotation and feeding of a cutting tool and a material, the control section performing cutting with vibration of the cutting tool relative to the material by combining a forward feed movement in the machining direction, in which the cutting tool machines the material, and a return movement in the counter-machining direction. A return movement setting section sets a pulse-like signal including a command for moving a cutting tool in the machining direction and a command for the return movement. A forward feed setting section makes the cutting tool reach a change point by combining the movement in the machining direction on the basis of the return movement setting section and the forward feed movement. A pulse-like signal is formed in sine waveform with an inflection point, and a phase of the inflection point for making the cutting tool reach the change point is set to a value different from a phase of the change point.

A machine tool and a control device for the machine tool for shortening the machining time of a workpiece in a case where the relative and reciprocal vibration of workpiece holder and tool post in the radial direction of the workpiece is stopped during a period from an initial point until when the workpiece and the cutting tool come into contact with each other is provided. In the machine tool, when threading the workpiece to form a threaded portion on the workpiece by relatively moving the workpiece and the cutting tool in the feed direction while relatively rotating the workpiece and the cutting tool 130 to perform multiple times of cutting processes along the same cutting path in a predetermined spiral form, the cutting tool is brought closer toward the workpiece in the feed direction from a predetermined initial point at which the workpiece and the cutting tool are separated from each other, the workpiece and the cutting tool come into contact with each other, and the threading is started with the contact. During the period from the initial point until when the workpiece and the cutting tool come into contact with each other, a controller stops the vibration of the cutting tool, and, in continuous cutting processes in the multiple times of cutting processes in the threading, the control means sets a phase position of the tool post in the vibration direction and stops the reciprocal vibration so that, when the workpiece and the cutting tool come into contact with each other, each of the continuous cutting processes has a predetermined phase in the reciprocal vibration relative to a rotation phase of the workpiece at the start of the threading.

A machine tool and a control apparatus thereof include an amplitude control unit to control the amplitude of reciprocal vibration by a vibration unit. The amplitude control unit is configured to reduce the amplitude of the reciprocal vibration by the vibration unit as a cutting tool is fed in a feeding direction when the cutting tool reaches a predetermined cutting tool work stopping position on a workpiece in the feeding direction (Z-axis direction) to prevent the cutting tool from cutting the workpiece beyond the cutting tool work stopping position.

A machine tool and a control apparatus thereof include an amplitude control unit to control the amplitude of reciprocal vibration by a vibration unit. The amplitude control unit is configured to reduce the amplitude of the reciprocal vibration by the vibration unit as a cutting tool is fed in a feeding direction when the cutting tool reaches a predetermined cutting tool work stopping position on a workpiece in the feeding direction (Z-axis direction) to prevent the cutting tool from cutting the workpiece beyond the cutting tool work stopping position.

To provide a control device for a machine tool capable of performing thread cutting while reducing the load on the machine tool from the oscillating operation, without extending the cycle time, and capable of reliably shredding chips in a case of performing the non-oscillating operation in the present pass after the oscillating operation in the previous pass. A control device for a machine tool includes: an oscillating operation execution determination unit that determines whether to execute an oscillating operation that causes the cutting tool to oscillate in the radial direction of the workpiece; an oscillation command generation unit that generates an oscillation command of the oscillating operation based on a determination result; a control unit that superimposes the oscillation command on a position command of the feed axis to generate a drive command. The oscillating operation execution determination unit determines to intermittently execute the oscillating operation, and the oscillation command generation unit generates an oscillation command so that a non-oscillating cutting portion of a present pass includes a portion at which oscillating cutting was performed in a previous pass, or so that an oscillating cutting portion of the present pass includes a portion at which non-oscillating cutting was performed in the previous pass.

A numerical control device for a machine tool, the machine tool including: a reference shaft that moves a tool or a workpiece; and a superimposition shaft that moves a tool or the workpiece. The numerical control device superimposes the movement amount of the reference shaft on the movement amount of the superimposition shaft. The numerical control device including a control computation unit that, in response to a superimposition control command, changes at least one of a first vibration rate, a second vibration rate, and a main shaft rotation speed on a basis of a first vibration command, a second vibration command and a main shaft rotation speed command such that the first vibration rate stays constant and the second vibration rate stays constant. The first vibration rate is a number of times that of the reference shaft vibrates per rotation of a main shaft.

A method for cutting a thread on a rotating workpiece by means of a cutting tool having a cutting edge. The method includes sequentially performing a number of passes, each pass includes simultaneously moving the cutting tool and/or the workpiece relative to each other along and oscillating the cutting tool towards and away from workpiece rotational such that the cutting edge exits and enters the workpiece forming an air cut. The air cuts performed in a final pass are longer than all the other passes.