Okazaki, Japan
Okazaki, Japan

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Patent
Okuma Corporation | Date: 2016-10-21

A main spindle controller of a machine tool varies a rotation speed of a main spindle that grips a workpiece to a varied maximum speed higher than a reference rotation speed set value as a set value of a reference rotation speed by a variation width set value as a set value of a variation width or a varied minimum speed lower than the reference rotation speed set value by the variation width set value in units of the tool path. At the same time, the main spindle controller refers to speed condition information that indicates a condition of the preliminarily stored reference rotation speed and variation width assuming that a chatter vibration is to be reduced, and when at least one of the reference rotation speed set value and the variation width set value does not satisfy the condition of the speed condition information.


A main spindle failure detection device for a machine tool includes a rotation speed detection unit, a reach time estimation unit, and a determining unit. The reach time estimation unit is configured to estimate a reach time in which the rotation speed of the main spindle reaches a predetermined rotation speed threshold using a non-linear model based on a rotation speed of the main spindle detected at a start of an inertia operation and a rotation speed of the main spindle detected after an elapse of preset measurement time from the start of the inertia operation. The determining unit is configured to compare the reach time estimated by the reach time estimation unit with a preset reach time in which the rotation speed reaches the rotation speed threshold, so as to determine a failure in the main spindle based on a result of the comparison.


Patent
Okuma Corporation | Date: 2016-10-03

In an NC device having a function as a monitoring apparatus for a machine tool, a monitoring parameter and a retracting parameter which are set and inputted through an input unit by an operator, can be stored in a storage unit. When, for example, monitoring is performed by using a load on a main spindle as machine information, a machining monitoring unit displays a monitored state on a monitor, and compares a threshold value, of the load on the main spindle, according to which occurrence of abnormality is determined, and which is set in the monitoring parameter, and an instruction load generated by a machine operation instruction unit with each other, to determine whether or not abnormality has occurred. When abnormality is determined as having occurred, a retracting instruction is transmitted to a retracting instruction unit according to the retracting parameter, and display is performed on the monitor.


Patent
OKUMA Corporation | Date: 2016-11-16

A window function calculator applies a Hann window function to Vd (n) to obtain a numeric value Vw (n). For twenty successive numeric values Vw(n) for every twenty numeric values (N=20), each of the Fourier calculators to executes Fourier calculation. Further, the SRSS calculators to calculate square root of sum of squares of SIM and COS components of respective orders of the results of Fourier calculation as numeric values A2, A3, A4, A5. A subtractor calculates a numeric value Ci=A3A5, while a subtractor calculates a numeric value Si=A4A2. A Frequency calculator calculates a numeric value Fi=(m+1+2*ATAN2 (Ci, Si)/)/(NT), which indicates the frequency identified. An amplitude calculator doubles the square root of the sum of squares of the numeric values Ci and Si, and calculates a numeric value Ai that indicates the amplitude of the frequency identified.


Patent
Okuma Corporation | Date: 2016-06-15

A main spindle load monitoring device indicates a main spindle load in a machine tool that includes a tool with a plurality of edges on a main spindle and performs a process of a workpiece while the tool rotates with the main spindle. The main spindle load monitoring device includes a main spindle load detecting unit configured to detect a load on the main spindle, a main spindle load conversion unit, and a display control unit. The main spindle load conversion unit is configured to convert a time course of the main spindle load detected by the main spindle load detecting unit into a change of the main spindle load with respect to a main spindle rotation angle. The display control unit is configured to indicate a value of the main spindle load converted by the main spindle load conversion unit on a display screen in a polar coordinates system.


Patent
Okuma Corporation | Date: 2016-04-13

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.


Patent
OKUMA Corporation | Date: 2016-03-17

A position control device for driving one control target, using two drive shafts, has position control units provided to the respective drive shafts. Each position control unit includes a calculation unit for calculating a torque command value before compensation, a deflection vibration reduction torque compensator for calculating a deflection torque estimate and calculating a deflection vibration reduction torque compensation amount, based on the deflection torque estimate and a deflection vibration reduction compensation gain, and a compensator gain calculation unit for outputting, upon receipt of a tandem control command, to the deflection vibration reduction torque compensator, a signal for outputting the deflection vibration reduction torque compensation amount and calculating the deflection vibration reduction compensation gain, and the each of the position control units outputs a value obtained by adding the deflection vibration reduction torque compensation amount to the torque command value before compensation as the torque command value.


A thermal displacement correcting apparatus includes a correction amount estimating device and a parameter automatic selecting device that, in a machine tool having two different sets of specifications that differ due to the presence/absence of a scale and different methods of measuring the lengths of a bed and a table, estimate a thermal displacement correction amount of the machine tool of each set of specifications. The two devices store a collection of parameters for an estimated thermal displacement calculation corresponding to each of the bed, the scale, the table, and a workpiece, as a database, and select the parameters belonging to the set of specifications from the database based on machine information according to each set of specifications, calculate estimated thermal displacements of the bed, the table, and the workpiece, or also the scale, according to the selected parameters, and combine the estimated thermal displacements.


Patent
Okuma Corporation | Date: 2016-02-01

An error identification method of a machine tool includes an initial position measurement step of indexing a main spindle head rotation axis to an initial angle to measure an initial position of a measured jig, a table reference angle calculation step of calculating a reference angle of the table, a reference position measurement step of indexing the table rotation axis to the reference angle and indexing the main spindle head rotation axis to the initial angle, a relative position measurement step of respectively indexing the table rotation axis and the main spindle head rotation axis to a plurality of predetermined angles, an arc approximation step of approximating the plurality of measured position values into an arc, and an error calculation step of calculating an error of a center position of the rotation axis, a tilt error of the rotation axis, or a tilt error of the translational axis.


Patent
OKUMA Corporation | Date: 2016-05-19

A multi-turn detector is configured to detect an amount of multiple turns of an input shaft using a plurality of resolvers. Each resolver includes a rotor portion and a stator portion. The rotor portion has a rotor core composed of a magnetic flux modulating component. The rotor portion rotates in accordance with rotation of the input shaft at a reduction gear ratio that is different from that of a rotor portion of another resolver. The stator portion has an excitation winding that excites an ac magnetic flux in a direction of an axis of rotation of the rotor portion and two detection windings that output ac signals that are obtained by performing amplitude modulation in accordance with a rotation angle of the rotor portion. The excitation windings and the detection windings of the plurality of resolvers are formed by conductor traces in a common multi-layer printed circuit board.

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