The present invention relates to an actively dampened centerless grinding process for a centerless grinding machine having wheels, between which there is arranged a part to be ground, and heads carrying the wheels, which process has moving the wheels closer to one another by applying pressure on the part for the grinding thereof, such that vibrations are generated in the grinding machine due to grinding, measuring the vibrations due to grinding, and introducing, depending on the measurement, an active damping force (F.sub.act) parallel to the force flow of the grinding machine and by means of using an inertial actuator acting directly on one of the heads, such that the vibrations due to grinding are attenuated.

A machine tool includes: a main spindle that holds a work piece; a tool holding unit that holds a tool for processing the work piece; a detection unit that detects vibration generated during processing of the work piece; and a processor that controls machining of the work piece performed by the tool, in which the processor compares a detected value detected by the detection unit with a predefined threshold value, interrupts the machining by releasing contact between the work piece and the tool at time of generation of chatter vibration or when there is a sign of the generation of the chatter vibration in which the detected value exceeds the threshold value, and analyzes the chatter vibration while the machining is being interrupted on basis of the detected value detected by the detection unit before the interruption.

An NC unit calculates the phase difference in chatter vibration during working on the basis of detection result of sound produced by working a workpiece by an end mill, increases the number of rotations of the end mill by a predetermined number if the phase difference is smaller than a first phase difference threshold, and decreases the number of rotations of the end mill by a predetermined number if the phase difference is larger than a second phase difference threshold. Further, if the phase difference is between the first phase difference threshold and the second phase difference threshold, the NC unit finds the resonance frequency of a machine tool by multiplying a chatter frequency by a correction factor that changes according to the chatter frequency, and calculates the number of rotations of the end mill on the basis of the resonance frequency, to obtain stable working with suppressed chatter vibration.

A machine tool includes: a display; a tool configured to machine a workpiece; a spindle configured to rotate the tool or the workpiece; a sensor configured to detect a vibration frequency of the spindle or the tool; and a processor configured to control the machine tool. The processor is configured to: detect a chatter vibration in the spindle or the tool based on the vibration frequency; based on a frequency of the chatter vibration, a rotation speed of the spindle, and the number of cutting edges of the tool, calculate an order corresponding to the number of vibrations of the tool during a period of time until a current rotation angle of a first cutting edge of the tool reaches a current rotation angle of a second cutting edge of the tool; and present order information on the display, the order information indicating a magnitude of the calculated order.

A computerized method of machining a workpiece including, prior to machining the workpiece, establishing, based on empirical data obtained from machining activity at an earlier time, an historical mapping indicating pairings of depth of cut and rpm at which undesirable chatter (UDC) did not occur during machining activity at an earlier time using at least one given type of milling machine, at least one given type of cutting tool and at least one given type of workpiece material, prior to commencing machining of the workpiece, programming a machine tool to machine the workpiece using a given type of milling machine, a given type of cutting tool and a given type of workpiece material at at least one depth of cut and rpm, which, based on the historical mapping, avoid UDC and operating the machine tool in accordance with the programming to machine the workpiece.

A computerized method of machining a workpiece including, prior to machining the workpiece, establishing, based on empirical data obtained from machining activity at an earlier time, an historical mapping indicating pairings of depth of cut and rpm at which undesirable chatter (UDC) did not occur during machining activity at an earlier time using at least one given type of milling machine, at least one given type of cutting tool and at least one given type of workpiece material, prior to commencing machining of the workpiece, programming a machine tool to machine the workpiece using a given type of milling machine, a given type of cutting tool and a given type of workpiece material at at least one depth of cut and rpm, which, based on the historical mapping, avoid UDC and operating the machine tool in accordance with the programming to machine the workpiece.

A display control device includes a calculation unit for calculating a first rotating speed on the basis of a vibration level detected by a vibration detection unit when the vibration level has exceeded a predetermined value, a change receiving unit for receiving a change instruction for changing a second rotating speed that is a rotating speed when the vibration level has exceeded the predetermined value to the first rotating speed, and a display control unit for performing control to display, on an operation screen, the first rotating speed, the second rotating speed, and a ratio display unit indicating a change ratio to a third rotating speed specified by a machining program, and performing control to display the first rotating speed at a position in the ratio display unit corresponding to a change ratio of the first rotating speed to the third rotating speed.

A computerized method of machining a workpiece including, prior to machining the workpiece, establishing, based on empirical data obtained from machining activity at an earlier time, an historical mapping indicating pairings of depth of cut and rpm at which undesirable chatter (UDC) did not occur during machining activity at an earlier time using at least one given type of milling machine, at least one given type of cutting tool and at least one given type of workpiece material, prior to commencing machining of the workpiece, programming a machine tool to machine the workpiece using a given type of milling machine, a given type of cutting tool and a given type of workpiece material at at least one depth of cut and rpm, which, based on the historical mapping, avoid UDC and operating the machine tool in accordance with the programming to machine the workpiece.

A display control device according to an embodiment controls display of a state of a machine tool that includes (i) an attachment portion to which a tool is attachable, (ii) a numerical control unit for controlling (a) movement of the attachment portion and (b) a rotating speed of the tool in accordance with a machining program and (iii) a vibration detection unit for detecting vibration of the tool. This display control device includes a display control unit for controlling display of time-series data indicating (i) a change in a vibration level detected by the vibration detection unit and (ii) a change in the rotating speed of the tool. Upon receiving an instruction to change the rotating speed, the display control unit controls the display so that a marker indicating the change instruction is superimposed on the time-series data.

A vibration information display device includes a monitor, a vibration information acquisition unit, an operating information acquisition unit, a storage unit, and a display control unit. The monitor displays information on the chatter vibrations. The vibration information acquisition unit acquires vibration information when the chatter vibrations are detected. The operating information acquisition unit acquires operating information of the machine tool when the chatter vibrations are detected. The storage unit stores the acquired vibration information and operating information. The display control unit displays the vibration information and the operating information stored in the storage unit on the monitor. Alternatively, the display control unit displays the vibration information stored in the storage unit on the monitor together with trajectory information of a blade edge of the tool included in the operating information.