Patents Assigned to Okuma Corporation
  • Publication number: 20200298355
    Abstract: A workpiece fixing jig for fixing a workpiece to a table and/or a pallet of a machine tool includes a base plate, a support block, a bolt, and a drop prevention unit. The base plate is clamped or unclamped to the table and/or the pallet. The support block is disposed upright on the base plate. The support block has a placement surface for the workpiece on a top surface of the support block. The bolt is housed in the support block to be movable up and down. The bolt is projected from the placement surface to be screwable into a lower surface of the workpiece. The drop prevention unit prevents a drop of the bolt from the inside of the support block.
    Type: Application
    Filed: March 9, 2020
    Publication date: September 24, 2020
    Applicant: OKUMA CORPORATION
    Inventor: Tomomi IDO
  • Patent number: 10780547
    Abstract: A machine tool includes a main shaft unit; a polishing head for processing a workpiece; and an unnecessary byproduct leakage preventing unit for preventing leakage of abrasive resulting from processing at or around a part of the workpiece, the part being processed, and wherein the unnecessary byproduct leakage preventing unit includes a cover provided separately from the polishing head, the cover having a structure that is open in three directions and that has walls in another three directions such that a protection space where to hold a part of the workpiece is defined, the cover for receiving the abrasive, and a movement mechanism for moving the cover so as to stay apart from the workpiece while the workpiece is not being processed and so as to have a part of the workpiece held in the protection space while the workpiece is being processed.
    Type: Grant
    Filed: April 23, 2018
    Date of Patent: September 22, 2020
    Assignee: OKUMA CORPORATION
    Inventors: Hiroyuki Sugiura, Shoichi Morimura
  • Patent number: 10784730
    Abstract: A rotor of a synchronous motor has a rotor core and a permanent magnet. The rotor core has a plurality of magnet insertion apertures and a plurality of slits. The permanent magnet is disposed in each of the magnet insertion apertures such that the magnetic poles of the permanent magnets are directed in a diameter direction. The slits are formed on an radially outer side of the magnet insertion aperture so as to align with intervals along a side of the permanent magnet. Magnetic paths are defined between adjacent slits. A gap that is a slot open in the axial direction of the rotor core is formed on the opposite side from a plurality of magnetic paths across the permanent magnet to adjust the magnetic resistance of the magnetic paths for making a change in magnetic flux between adjacent magnetic paths small.
    Type: Grant
    Filed: October 23, 2018
    Date of Patent: September 22, 2020
    Assignee: OKUMA CORPORATION
    Inventors: Takanori Yokochi, Tatsuya Shizu
  • Patent number: 10784803
    Abstract: A position control device includes a subtracter for subtracting a q-axis current detection value iq from a q-axis current command value iq* to output a q-axis current error ?iq, an adder for adding a q-axis current compensation amount iqc* for compensating for response timing of q-axis current to the q-axis current error ?iq, a q-axis current controller for amplifying an output of the adder by I-P control to calculate a q-axis voltage error ?vq and calculating a q-axis voltage command value vq* on the basis of the q-axis voltage error ?vq, and a second adder for adding a q-axis voltage feedforward amount vqf corresponding to a time derivative value s·iq of the q-axis current to the q-axis voltage command value vq* to calculate a final q-axis voltage command value.
    Type: Grant
    Filed: June 14, 2019
    Date of Patent: September 22, 2020
    Assignee: OKUMA CORPORATION
    Inventor: Satoshi Eguchi
  • Patent number: 10760994
    Abstract: It is an object to perform an abnormality diagnosis for a feed axis without additionally adding a sensor or the like. A frequency characteristic of a feed axis and a damage frequency that occurs when the feed axis that has been damaged performs an axis operation are obtained, a frequency where a gain is maximized in the obtained frequency characteristic is calculated, and a feed velocity where the frequency matches the damage frequency is calculated. An axis operation is performed on the feed axis with the calculated feed velocity, and a frequency analysis is performed on servo information regarding a control of a servo motor during the axis operation. Then, the presence and absence of a peak of the damage frequency is confirmed from a result of the frequency analysis, and when the peak is present, it is determined that it is abnormal.
    Type: Grant
    Filed: July 19, 2017
    Date of Patent: September 1, 2020
    Assignee: Okuma Corporation
    Inventor: Takumi Hongo
  • Patent number: 10737333
    Abstract: A machine tool includes: a turret configured to hold a tool through a clamp mechanism; a workpiece main spindle device configured to rotatably hold a workpiece; a switching unit configured to change a clamp state of the clamp mechanism by using rotation torque of the workpiece main spindle device; and an in-machine robot configured to move the switching unit. The clamp mechanism includes a torque input hole to which rotation torque is applied to change the clamp state. The switching unit includes an input shaft coupled with the workpiece main spindle device, an output shaft coupled with the torque input hole of the clamp mechanism and configured to output torque to the torque input hole, and a transmission mechanism configured to transfer, to the output shaft, the rotation torque of the workpiece main spindle device input through the input shaft.
    Type: Grant
    Filed: January 23, 2019
    Date of Patent: August 11, 2020
    Assignee: OKUMA CORPORATION
    Inventors: Tomoki Hayashi, Shoichi Morimura
  • Patent number: 10725465
    Abstract: A state diagnostic device collects a usage state and diagnostic data of components, and selects, from the collected diagnostic data, at least one of diagnostic data obtained in a state where the usage state of the components is a truly normal state and diagnostic data obtained in a state where the usage state of the components is a truly abnormal state. The selected diagnostic data is defined as master data. A diagnosis result obtained by diagnosing the master data based on a current diagnostic model is compared with a diagnosis result obtained by diagnosing the master data based on a new diagnostic model, and whether the current diagnostic model is consistent with the new diagnostic model is determined. When the consistency is satisfied, the diagnostic model is updated from the current diagnostic model to the new diagnostic model.
    Type: Grant
    Filed: February 21, 2018
    Date of Patent: July 28, 2020
    Assignee: Okuma Corporation
    Inventors: Takahiro Tamakoshi, Hiroshi Ueno, Tomoharu Ando
  • Publication number: 20200230764
    Abstract: A method includes four steps, (1) setting an initial tool temperature, (2) estimating a temperature of a tool or a position measurement sensor based on the initial tool temperature and a temperature of a spindle, (3) estimating an amount of thermal displacement of the tool or the position measurement sensor with a preliminarily set tool thermal displacement estimation formula based on the estimated temperature, and (4) moving a feed shaft of the machine tool based on the estimated amount of thermal displacement to perform a correction. In the second step, the temperature of the spindle is measured, then a tool-mounted portion temperature of the spindle from the measured temperature is estimated. Further, the temperature of the tool or the position measurement sensor is estimated with the tool-mounted portion temperature, the initial tool temperature of the tool or the position measurement sensor, and the preliminarily set tool temperature estimation formula.
    Type: Application
    Filed: December 24, 2019
    Publication date: July 23, 2020
    Applicant: OKUMA CORPORATION
    Inventor: Yuji MIZOGUCHI
  • Patent number: 10702962
    Abstract: A swarf handling apparatus installed in a machining tool that performs machining operation accompanied with production of stringy swarf includes a swarf catching device. The swarf catching device includes a holder unit that holds the stringy swarf when the stringy swarf makes contact with the holder unit. The swarf catching device causes the holder unit to be floated in a region around a machining point in such a manner that the position of the holder unit is varied relative to the machining point, for catching the stringy swarf in the holder unit.
    Type: Grant
    Filed: April 27, 2018
    Date of Patent: July 7, 2020
    Assignee: OKUMA CORPORATION
    Inventor: Hiroyuki Sugiura
  • Patent number: 10688612
    Abstract: A machine tool is provided which can execute various works while suppressing increase in cost or size. The machine tool includes a tool spindle device which is a movable member which can move with respect to a mounting surface of the machine tool, and one or more serial-manipulator-type robots attached on the tool spindle device, which can move with the tool spindle device, and which have two or more degrees of freedom, and the robot includes two or more end effectors provided at positions different from each other with one or more joints therebetween.
    Type: Grant
    Filed: May 12, 2017
    Date of Patent: June 23, 2020
    Assignee: OKUMA CORPORATION
    Inventor: Shoichi Morimura
  • Patent number: 10663942
    Abstract: A position control apparatus includes an inversion detector which detects an inversion of a position command and generates an inversion detection signal, a deflection characteristic storage unit which stores a deflection characteristic representing an amount of deflection with respect to a torque command, and an inversion correction calculator which calculates an inversion correction amount. The inversion correction calculator stores a torque command immediately before the inversion, and calculates the inversion correction amount from a difference between an amount of deflection immediately before inversion in which the stored torque command is checked with the deflection characteristic, and an amount of deflection after the inversion in which a value obtained by inverting a sign of the stored torque command is checked with the deflection characteristic. A value obtained by adding the inversion correction amount to the position command value is used for position error calculation.
    Type: Grant
    Filed: July 26, 2018
    Date of Patent: May 26, 2020
    Assignee: OKUMA CORPORATION
    Inventors: Hisashi Kondou, Tomohiro Shibata, Yuji Uchida, Takeshi Sakai
  • Patent number: 10649014
    Abstract: A method measures a frequency characteristic at a feed axis control unit configured to drive a motor in accordance with a velocity command value to control a velocity or a position of a movable portion of a driven body. The velocity command value includes a velocity reference value from a host device or a velocity command calculator and a sweep signal swept in order to measure the frequency characteristic. The method includes moving the feed axis in one direction by commanding the velocity reference value where a moving velocity of the feed axis is constant, exciting by providing a sine wave having an amplitude less than a magnitude of the velocity reference value to the sweep signal, and measuring the frequency characteristic of a feed axis drive system including the motor.
    Type: Grant
    Filed: February 23, 2017
    Date of Patent: May 12, 2020
    Assignee: Okuma Corporation
    Inventors: Masashi Miyaji, Takashi Norihisa
  • Patent number: 10632611
    Abstract: The machine tool includes a tool post linearly movable along a direction parallel to an X axis and a direction parallel to a Z axis, a workpiece spindle which retains a workpiece in a condition rotatable about an axis parallel to the Z axis, and an in-machine robot which is installed in a machining chamber and has joints. The joints of the in-machine robot include a base joint rotatable about an axis parallel to the Z axis, and three parallel joints rotatable about an axis orthogonal to the axis of rotation of the base joint, the parallel joints being located on a distal end side of the base joint and successively arranged from the base joint. The axis of rotation of the base joint is displaced from that of the workpiece spindle.
    Type: Grant
    Filed: December 3, 2018
    Date of Patent: April 28, 2020
    Assignee: OKUMA CORPORATION
    Inventor: Shoichi Morimura
  • Patent number: 10603752
    Abstract: A machine tool that cuts a workpiece by a rotary tool includes a tool spindle device that holds the rotary tool in a manner to allow self-rotation with a predefined tool rotational axis Rt as a center, one or more in-machine robots, and a connecting mechanism that attaches the in-machine robot on the tool spindle device so that the in-machine robot moves independently from the rotary tool at a periphery of the tool spindle device with the tool rotational axis Rt as a center.
    Type: Grant
    Filed: April 28, 2017
    Date of Patent: March 31, 2020
    Assignee: OKUMA CORPORATION
    Inventor: Shoichi Morimura
  • Patent number: 10594242
    Abstract: A controller for a motor determines a voltage limit circle based on a velocity of the motor, a DC bus voltage of an inverter, calculates a q axis current limit value based on the voltage limit circle and a predetermined current limit circle, determines, as a q axis current command value, a value obtained through a limit process which is applied using the q axis current limit value to a q axis current value calculated in accordance with a torque command value, and determines a corresponding d axis current value based on the q axis current command value.
    Type: Grant
    Filed: January 30, 2019
    Date of Patent: March 17, 2020
    Assignee: OKUMA CORPORATION
    Inventor: Satoshi Eguchi
  • Patent number: 10585416
    Abstract: An abnormality diagnostic method executes causing the feed axis to perform an axis operation in a predetermined diagnosis condition to obtain servo information according to a control of the servomotor, performing a frequency analysis on the obtained servo information, obtaining a damage frequency generated while the feed axis whose bearing is damaged performs the axis operation, from a result of the frequency analysis, and comparing the obtained damage frequency with a predetermined threshold to determine a presence/absence of an abnormality. In the determining, before the damage frequency is compared with the threshold, a determination whether a vibration frequency of the bearing interferes with a vibration frequency generated while a rolling element passes through a nut of the ball screw or not is performed, and the comparison is performed by setting the respective thresholds that are different in a case of the interference and a case of no interference.
    Type: Grant
    Filed: October 24, 2018
    Date of Patent: March 10, 2020
    Assignee: Okuma Corporation
    Inventor: Takumi Hongo
  • Patent number: 10578723
    Abstract: In a position detector for converting, into position information, two signals shifted in phase by 90 degrees from each other, a phase correction value calculator for calculating a phase correction value for correcting a phase difference between the two signals calculates a phase change value representing a change in the phase correction value, to find a next phase correction value based on the phase change value and a present phase correction value. A virtual change value calculator calculates, based on second-order components obtained by Fourier analysis of a radius value, a virtual phase change value representing another change in the phase correction value obtained when changes in offset and amplitude ratio are ignored, and a virtual amplitude change value representing a change rate in an amplitude ratio correction value obtained when a change in the phase difference is ignored.
    Type: Grant
    Filed: June 13, 2017
    Date of Patent: March 3, 2020
    Assignee: OKUMA CORPORATION
    Inventor: Katsutoshi Iwazawa
  • Patent number: 10545033
    Abstract: 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.
    Type: Grant
    Filed: May 19, 2016
    Date of Patent: January 28, 2020
    Assignee: OKUMA CORPORATION
    Inventors: Yasukazu Hayashi, Koji Kitagawa, Yasunori Kawakami, Hiroaki Matsuura
  • Patent number: 10513001
    Abstract: A bearing diagnostic device includes an identification unit and an obtaining unit. The identification unit is configured such that a feature quantity, an operation condition of a main spindle at a measurement of the feature quantity, and specification data of the bearing used for the main spindle are preliminarily configured as inputs. The identification unit is configured such that a normal state and an abnormal state are preliminarily configured as outputs. The identification unit is configured to create an identification model through machine learning. The obtaining unit is configured to obtain the feature quantity, the operation condition at the measurement of the feature quantity, and the specification data of the bearing used for the main spindle.
    Type: Grant
    Filed: July 7, 2017
    Date of Patent: December 24, 2019
    Assignee: Okuma Corporation
    Inventor: Tomoharu Ando
  • Patent number: 10496072
    Abstract: A temperature of a portion of which the temperature is difficult to directly measure is accurately estimated in a simple method. In S1, information about a coolant discharging/stopping state is obtained. As the information about the coolant discharging/stopping state, a flag is used such that the flag represents 1 for the discharging state and the flag represents 0 for the stopping state. Next, in S2, temperature data is obtained from temperature sensors provided in components of a machine tool, a machining space, and a coolant tank. Next, in S3, lag process is performed for the coolant discharging/stopping state flag, and coefficients for measured temperatures of the coolant and the structure are calculated. Next, in S4, the measured temperatures are multiplied by the coefficients, and an estimated temperature of a portion to which the temperature sensor is not attached is calculated.
    Type: Grant
    Filed: November 3, 2017
    Date of Patent: December 3, 2019
    Assignee: Okuma Corporation
    Inventor: Yuji Mizoguchi