A spindle speed adjusting device in machining is provided, which may include a plurality of signal detection modules, a signal capturing module and a signal processing module. Each of the signal detection modules may keep measuring the vibration signals in machining. The signal capturing module may capture the vibration signals. The signal processing module may execute a transmissibility analysis to obtain the transmissibility between the signal detection modules, and execute a frequency response fitting according to the transmissibility to obtain a plurality of system dynamic parameters, and then execute a stability lobe diagram analysis to calculate the optimized spindle speed of the machining tool so as to make the machining tool operate at the optimized spindle speed. The signal processing module may repeatedly execute the transmissibility analysis, the frequency response fitting and the stability lobe diagram analysis to keep updating the optimized spindle speed until the machining process ends.

A feedback control numerical machine tool and a method thereof are provided. The machine tool includes at least two spindles, an acoustic frequency detecting module, at least two spindle position detecting modules, and a control module. The spindles machine a workpiece. The acoustic frequency detecting module detects an acoustic frequency of the spindles when machining the workpiece. The spindle position detecting modules detects position information of the spindles when machining the workpiece. The control module acquires the acoustic frequency and the position information of the spindles, monitors whether any of the spindles chatters according to the acoustic frequency of the spindles, and performs chattering avoidance to the spindle that chatters according to the position information of the spindles. As such, the present disclosure performs chattering monitoring to a plurality of spindles and avoids the chattering immediately.

A machining status display apparatus includes a display device having a display screen, a stability lobe picture creator creating, based on specifications of a tool to be used, display picture data for displaying a stability lobe as a correlation diagram between a spindle rotation speed and a limit depth of cut of the tool above which regenerative chatter occurs, a first machining information picture creator creating display picture data for displaying machining related information other than regenerative chatter corresponding to set machining conditions, and a display controller displaying the stability lobe and the machining related information with the stability lobe and the machining related information superimposed one on another on the display screen of the display device based on the display picture data created by the stability lobe picture creator and the display picture data created by the first machining information picture creator.

A chatter avoidance method and device is provided, including steps of: providing a stable operating condition plot; partially removing a first layer of a workpiece with a predetermined first removal depth according to a safe removal depth of the stable operating condition plot and sensing a chatter caused by the removal operation; if no chatter is sensed, completing the removal operation, otherwise, continuing to partially remove the first layer with a second removal depth less than the predetermined first removal depth; and determining a minimum removal depth according to the removal operation, and removing a last layer of the workpiece with a last removal depth less than or equal to the minimum removal depth, allowing the workpiece to have a target thickness. The disclosure prevents a chatter from continuously occurring without requiring a shut-down and thereby maintains a desired production rate.

A system, method, and computer-readable medium for providing a user interface. The system includes circuitry configured to generate chatter information based on sensor data collected from a machining operation of a machine performed at a previously selected tool speed setting. The chatter information includes a chatter level value and a chatter frequency value. A plurality of different candidate tool speed settings is determined based on the generated chatter frequency value from the machining operation. The circuitry generates the user interface that includes a plurality of different tool speed settings, including the previously selected tool speed setting and the plurality of different candidate tool speed settings for selection by a user. The user interface is configured to indicate the chatter level value for the previously selected.

A chatter avoidance method and device is provided, including steps of: providing a stable operating condition plot; partially removing a first layer of a workpiece with a predetermined first removal depth according to a safe removal depth of the stable operating condition plot and sensing a chatter caused by the removal operation; if no chatter is sensed, completing the removal operation, otherwise, continuing to partially remove the first layer with a second removal depth less than the predetermined first removal depth; and determining a minimum removal depth according to the removal operation, and removing a last layer of the workpiece with a last removal depth less than or equal to the minimum removal depth, allowing the workpiece to have a target thickness. The disclosure prevents a chatter from continuously occurring without requiring a shut-down and thereby maintains a desired production rate.

A sensorless method for machine tool chatter detection. When the machine tool spindle is running, a spindle motor torque signal is analyzed in the time domain to determine whether a bit is currently cutting a workpiece. When not cutting, an air-cut reference signal is stored for later use. When cutting, the spindle motor torque signal, along with positioning servo motor signals, are converted to the frequency domain and filtered. Filtering steps include removal of the air-cut reference signal via spectral subtraction, removal of spindle harmonic components, removal of artificial peaks due to aliasing effects, and removal of artificial peaks due to encoder error effects. After filtering, indicator criteria are evaluated to detect chatter, including a magnitude of the filtered torque signal for servo data and a magnitude ratio of the filtered torque signal to the air-cut reference signal for spindle data. Corrective action is taken when chatter is detected.

A tool holder is configured for rotation about a tool holder axis of rotation defining an axial direction. The tool holder, at one axial longitudinal end thereof, has a tool section with a tool-receiving formation for receiving a tool and, at the opposite axial longitudinal end, has a coupling section with a coupling formation for torque-transmitting coupling to a machine spindle of a machine tool. A measuring apparatus is configured for acquiring data relating to the operation of the tool holder. The measuring apparatus has a sensor, in particular an acceleration sensor, with at least two measurement axes. The two measurement axes are oriented substantially radially with respect to the tool holder axis of rotation.

A sensorless method for machine tool chatter detection. When the machine tool spindle is running, a spindle motor torque signal is analyzed in the time domain to determine whether a bit is currently cutting a workpiece. When not cutting, an air-cut reference signal is stored for later use. When cutting, the spindle motor torque signal, along with positioning servo motor signals, are converted to the frequency domain and filtered. Filtering steps include removal of the air-cut reference signal via spectral subtraction, removal of spindle harmonic components, removal of artificial peaks due to aliasing effects, and removal of artificial peaks due to encoder error effects. After filtering, indicator criteria are evaluated to detect chatter, including a magnitude of the filtered torque signal for servo data and a magnitude ratio of the filtered torque signal to the air-cut reference signal for spindle data. Corrective action is taken when chatter is detected.

An apparatus of controlling a chattering of a machine tool includes an acceleration sensor installed at a forced frequency part of the machine tool to detect a chattering signal of the machine tool; a monitor including a chattering output unit for displaying a chattering value in a graph form, a chattering correction direction display unit for outputting an increase or a decrease of a rotation amplitude and a rotation amplitude variable period, and a parameter input unit for inputting an increase or a decrease ratio of the rotation amplitude and a time corresponding to the rotation amplitude variable period; and a control unit for adjusting the rotation amplitude and the rotation amplitude variable period manually or automatically, which stabilizes the chattering of the machine tool and reduces a vibration and a noise caused by the chattering and prevents abnormal wear and damage to the machine tool.