In order to improve the machining freedom of a workpiece while suppressing a cost increase, a tool rest for a machine tool includes a cutting tool holder having a plurality of parallel cutting tool fixing grooves to which a shank of a cutting tool can be fixed, and a tool holder that holds a tool for machining a workpiece gripped by a spindle that is capable of rotating about a spindle axis AX0. The tool holder includes a shaft part that is fixed to the cutting tool fixing groove, and a holding part. The holding part holds, as the tool that performs machining about a machining axis AX4, at least one of a rotary tool and a non-rotary tool in which the machining axis AX4 extends along the spindle axis AX0.

An operational control method is provided for a machine tool that includes a plurality of tool holders with a cutting-tool. The machine tool relatively moves the tool holders with respect to a workpiece to process the workpiece. The operational control method includes determining whether an abnormality has occurred in the cutting-tool during a processing or not, determining whether a simultaneous processing in which at least two or more of the tool holders perform the processings to an identical workpiece is being performed or not and whether the cutting-tool having the detected abnormality is the cutting-tool that is performing the simultaneous processing or not when the abnormality is detected, and causing the tool holder with the cutting-tool having the detected abnormality to take an abnormality avoidance operation and another of the tool holders to take a response operation based on a determination result at the determining of the simultaneous processing.

An operational control method is provided for a machine tool that includes a plurality of tool holders with a cutting-tool. The machine tool relatively moves the tool holders with respect to a workpiece to process the workpiece. The operational control method includes determining whether an abnormality has occurred in the cutting-tool during a processing or not, determining whether a simultaneous processing in which at least two or more of the tool holders perform the processings to an identical workpiece is being performed or not and whether the cutting-tool having the detected abnormality is the cutting-tool that is performing the simultaneous processing or not when the abnormality is detected, and causing the tool holder with the cutting-tool having the detected abnormality to take an abnormality avoidance operation and another of the tool holders to take a response operation based on a determination result at the determining of the simultaneous processing.

A technology capable of improving the accuracy of true-circular machining while avoiding an occurrence of intermittent cutting. A control unit of a machine tool determines an intermediate center position (Pi) in the moving direction for each divided rotation angle (E) smaller than a single rotation of the spindle and an intermediate eccentric radius (ri) around the intermediate center position (Pi) according to an initial position (Po) of the cutting edge in contact with the workpiece in the moving direction, the eccentric center position (Pc), and the eccentric radius (rc) to keep the cutting edge in contact with the workpiece as the moving object moves in the moving direction within a predetermined maximum feed speed (F) until a true-circular machining around the eccentric center position (Pc) is complete on the workpiece.

A technology capable of improving the accuracy of true-circular machining while avoiding an occurrence of intermittent cutting. A control unit of a machine tool determines an intermediate center position (Pi) in the moving direction for each divided rotation angle (E) smaller than a single rotation of the spindle and an intermediate eccentric radius (ri) around the intermediate center position (Pi) according to an initial position (Po) of the cutting edge in contact with the workpiece in the moving direction, the eccentric center position (Pc), and the eccentric radius (rc) to keep the cutting edge in contact with the workpiece as the moving object moves in the moving direction within a predetermined maximum feed speed (F) until a true-circular machining around the eccentric center position (Pc) is complete on the workpiece.

A downhole tool assembly includes a tubular having a turned-down region and a raised region extending axially away from the turned-down region. An inner diameter surface of the tubular in the turned-down region has a higher ellipticity than an outer diameter surface in the turned-down region. The outer diameter surface in the turned-down region defines a first center that is offset from a second center defined by the outer diameter surface of the tubular away from the turned-down region. The downhole tool assembly also includes a cylindrical tool disposed at least partially in the turned-down region.

A downhole tool assembly includes a tubular having a turned-down region and a raised region extending axially away from the turned-down region. An inner diameter surface of the tubular in the turned-down region has a higher ellipticity than an outer diameter surface in the turned-down region. The outer diameter surface in the turned-down region defines a first center that is offset from a second center defined by the outer diameter surface of the tubular away from the turned-down region. The downhole tool assembly also includes a cylindrical tool disposed at least partially in the turned-down region.

A machine tool control device according to one aspect of the present disclosure, which can prevent a workpiece from flying out, comprises: a total turning inertia estimation unit that, estimates the total turning inertia on the basis of feedback from a turning axis by causing the turning axis to rotate, said total turning inertia being the total inertia, around the turning axis, of the turning axis and an object that rotates together with the turning axis; a workpiece turning inertia estimation unit that estimates the workpiece turning inertia on the basis of the total turning inertia when a retention unit is not retaining a workpiece and the total turning inertia when the retention unit is retaining a workpiece, said workpiece turning inertia being the inertia, around the turning axis, of the workpiece; a maximum rotational speed calculation unit that, on the basis of the workpiece turning inertia, calculates the maximum rotational speed of the turning axis, at which the maximum energy when the workpiece separates from the retention unit is equal to a preset upper limit value; and a rotational speed limiting unit that limits the rotational speed of the turning axis so as not to exceed the maximum rotational speed.

A machine tool control device according to one aspect of the present disclosure, which can prevent a workpiece from flying out, comprises: a total turning inertia estimation unit that, estimates the total turning inertia on the basis of feedback from a turning axis by causing the turning axis to rotate, said total turning inertia being the total inertia, around the turning axis, of the turning axis and an object that rotates together with the turning axis; a workpiece turning inertia estimation unit that estimates the workpiece turning inertia on the basis of the total turning inertia when a retention unit is not retaining a workpiece and the total turning inertia when the retention unit is retaining a workpiece, said workpiece turning inertia being the inertia, around the turning axis, of the workpiece; a maximum rotational speed calculation unit that, on the basis of the workpiece turning inertia, calculates the maximum rotational speed of the turning axis, at which the maximum energy when the workpiece separates from the retention unit is equal to a preset upper limit value; and a rotational speed limiting unit that limits the rotational speed of the turning axis so as not to exceed the maximum rotational speed.

An NC lathe includes an energization signal switching unit for switching an energization signal set for each electric device between an energization required state and an energization non-required state, a prohibition signal switching unit for switching an energization prohibition signal set for each electric device between a prohibited state and a permitted state, a signal determination unit that determines whether or not each electric device is in a power saving state in which the energization signal for the electric device is in the energization required state and the energization prohibition signal is in the prohibited state, and a saving calculation unit that determines a cumulative duration of the power saving state, computes a device-specific power saving for each electric device on the basis of the cumulative duration, and calculates a power saving by adding together the device-specific power savings.