A drilling machine performs a feed operation while rotating a spindle, suspends the feed operation of the spindle for a predetermined dwell time at a predetermined hole bottom position, and then performs drilling by retreating the spindle. A controller for controlling the drilling machine calculates the dwell time based on a prescribed rotation amount in response to specification of the prescribed rotation amount (dwell rotation amount) at the hole bottom position.

A motor control device is a motor control device which controls a spindle motor of a machine tool, the device including: a low-pass filter which averages torque command values or drive current values of the spindle motor and calculates averaged load information of the spindle motor; and a time constant calculation unit which calculates, as a time constant of the low-pass filter, a first time constant based on a cut-off frequency according to the rotation number of the spindle driven by the spindle motor, or a second time constant based on a cut-off frequency according to a value produced by multiplying a of cutting tooth number of a tool by the rotation number of the spindle.

A control apparatus of a machine tool including a feed axis, which is driven by a feed axis motor, includes a load torque estimation unit configured to estimate a load torque acting on a spindle motor, based on a torque command to the spindle motor which drives a spindle axis of the machine tool, and a speed of the spindle motor; and a speed control unit configured to control a speed of a feed axis motor such that the load torque estimated by the load torque estimation unit follows a prescribed load torque target value.

A numerical control device (1) of a machine tool capable of controlling its spindle rotating speed includes: a program analyzing unit (2) that reads ahead a machining program (6) by one block or more and analyzes a command for the machine tool; and a command determining unit (3) that determines, based on a result analyzed by the program analyzing unit (2), whether a command posterior to a spindle control command causes any machining problem when the command is executed during a spindle rotating speed change, outputs a first command, in which some problem occurs in the machining, after the spindle rotating speed reaches the commanded rotating speed, and output a second command, which is other than the first command, before the spindle rotating speed reaches the commanded rotating speed.

An apparatus includes vibration data obtainer 30 obtaining data on vibration caused by a tool in cutting, a vibration frequency calculator 22 calculating a vibration frequency of the tool by analyzing the obtained vibration data, a regenerative chatter detector 23 detecting whether regenerative chatter occurs by comparing the calculated vibration frequency of the tool with a spindle rotation number, and a spindle rotation controller 24 gradually decreasing or increasing the spindle rotation number when occurrence of regenerative chatter vibration is detected, and a stable rotation number calculator 25 monitoring variation of the vibration frequency of the tool and determining a spindle rotation number when the variation of the vibration frequency exceeds a predetermined reference value to be a stable rotation number.

An apparatus for detecting the status of a tool in a machine tool may include: a sensor unit configured to sense acceleration of a spindle of the machine tool in an x-axis direction and a y-axis direction during processing; and a processing device configured to convert the x-axis signal and the y-axis signal, sensed by the sensor unit, into signals capable of representing a cutting force by processing the x-axis and y-axis signals, detect a resultant force, and plot the detected resultant force on a polar coordinate system.

An object is to provide a numerical control system of a machine tool which can check a parameter that needs to be adjusted for each of a spindle and a motor. A numerical control system of a machine tool includes a parameter check function unit for checking a drive control parameter of a spindle, and the parameter check function unit includes: an acceleration/deceleration time measurement unit which measures an acceleration/deceleration time that elapses after the spindle receives an acceleration command and/or a deceleration command until the completion of acceleration and/or the completion of deceleration; an acceleration/deceleration time specified value storage unit which stores a specified value of the acceleration/deceleration time that is previously determined for each specification of the machine tool; and a determination unit which compares the acceleration/deceleration time measured with the acceleration/deceleration time measurement unit and the specified value stored in the acceleration/deceleration time specified value storage unit so as to determine whether or not the drive control parameter of the spindle is proper.

A numerical controller decelerates a spindle feed rate in a bite portion to a bite velocity lower than a commanded feed rate when drilling is carried out and then, after passage through a velocity recovery point where a measured spindle load is made substantially constant, accelerates the spindle feed rate from the bite velocity to the commanded feed rate.

A control apparatus of a machine tool, the control apparatus including: a numerical control unit configured to create a spindle axis command and a feed axis command according to a tapping program; a spindle axis control unit configured to control rotational operation of the spindle axis according to the spindle axis command; a rotation detector configured to detect a rotation position of the spindle axis; and a feed axis control unit configured to control feeding operation of the feed axis according to the feed axis command on the basis of the rotation position. The numerical control unit is further configured to include, in the spindle axis command, a speed command value during return that does not depend on maximum rotation speed during machining of the spindle axis and that is higher than the maximum rotation speed during machining, as a command of return operation.

A numerical controller includes: a vibration amplitude specifying unit for specifying an amplitude of a vibration component generated by a blade of a tool being brought into contact with a workpiece at a predetermined cycle, due to rotation of a spindle out of a spindle load; a gain calculating unit for calculating a gain of PID control such that an output of the feed speed is uninfluenced by the amplitude, based on the amplitude of the vibration component specified by the vibration amplitude specifying unit; and a speed control unit for outputting a feed speed of the spindle controlled by the PID control, by using the gain calculated by the gain calculating unit.