Patents Assigned to Okuma Corporation
  • 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
  • Patent number: 10468924
    Abstract: A rotor for a flux-barrier-type reluctance motor having a plurality of poles formed in a circumferential direction includes a plurality of slits provided for each pole, a permanent magnet partially inserted into the slits in such a manner that magnetic poles of the permanent magnet are directed substantially orthogonal to the slit, a slit for a movable element disposed radially inside the permanent magnet disposed at an innermost position in a radial direction, and a movable element made of a magnetic material and inserted into the cavity, the movable element being capable of moving in the slit for the movable element in the circumferential direction. A radially inner side of the innermost slit into which the permanent magnet is inserted and radially outer and inner sides of both the slit for the movable element and the movable element are in a concentric circular-arc shape.
    Type: Grant
    Filed: May 4, 2017
    Date of Patent: November 5, 2019
    Assignee: OKUMA CORPORATION
    Inventor: Takanori Yokochi
  • Publication number: 20190301975
    Abstract: A method for diagnosing an abnormality of rolling bearing includes: measuring a vibration of a rotator; performing a frequency analysis on the vibration to calculate a magnitude of a vibration at each frequency; calculating a characteristic frequency as a frequency of a vibration from a specification of the rolling bearing and a rotation speed of the rotator at a vibration measurement in the measuring; calculating a vibration value from which an effect of the rotation speed is removed by dividing a magnitude of a vibration at the characteristic frequency by a value including a base and an exponent, the base being a predetermined physical quantity in a proportional relation with an angular velocity of the rotator at the vibration measurement in the measuring, the exponent being a positive number; calculating an evaluation index based on the vibration value; and determining an existence of an abnormality based on the evaluation index.
    Type: Application
    Filed: March 25, 2019
    Publication date: October 3, 2019
    Applicant: OKUMA CORPORATION
    Inventors: Hiraku SUGIURA, Issei KOIKE
  • Patent number: 10409267
    Abstract: 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.
    Type: Grant
    Filed: October 21, 2016
    Date of Patent: September 10, 2019
    Assignee: Okuma Corporation
    Inventor: Kohei Nishimura
  • Patent number: 10391559
    Abstract: A machine tool includes a workpiece spindle device which rotates a workpiece, a tool post which can move a tool in a first axis direction (X-axis direction) which is a radial direction of the workpiece and a second axis direction (Z-axis direction) which is an axial direction of the workpiece, and an articulated robot including a plurality of arms, a plurality of joints, and end effectors. The plurality of joints connect the plurality of arms in a rotatable manner around an axis parallel to a third axis (Y-axis) orthogonal to the first axis and the second axis, and the end effectors move in a plane parallel to a movement plane of the tool.
    Type: Grant
    Filed: May 24, 2017
    Date of Patent: August 27, 2019
    Assignee: OKUMA CORPORATION
    Inventor: Shoichi Morimura
  • Patent number: 10386252
    Abstract: A position control apparatus is provided that can perform accurate nonlinear compensation control immediately after the apparatus is activated. At a time of acceleration, a signal amplification ratio is calculated and designated for each signal vector element based on information related to acceleration/deceleration at a starting time and the structure of a signal vector that is determined for a target plant, and as a result, a signal vector for which the strength of linear independence is increased is generated. Because the strength of the linear independence condition of the signal vector is increased, the speed of convergence of identification for a low-frequency disturbance element, such as a gravitational torque or a sliding-mode load torque, can be increased.
    Type: Grant
    Filed: August 21, 2014
    Date of Patent: August 20, 2019
    Assignee: OKUMA CORPORATION
    Inventor: Satoshi Eguchi
  • Patent number: 10371139
    Abstract: A hydraulic pressure control device comprising: a hydraulic sensor provided between a hydraulic pump and a load; a speed command arithmetic unit configured to output a speed command value Vc based on a difference between a hydraulic pressure detection value Pd from the hydraulic sensor and a hydraulic pressure command value Pc; a torque command value arithmetic unit configured to calculate a torque command value Tc based on a difference between a speed detection value Vd of a motor and the speed command value Vc; a current controller configured to control current of the motor based on the torque command value Tc; and a hydraulic pressure abnormality detector configured to detect whether a hydraulic circuit has abnormality based on the speed command value Vc and an operating condition of the load of the hydraulic circuit commanded from an upper-level control device.
    Type: Grant
    Filed: September 22, 2015
    Date of Patent: August 6, 2019
    Assignee: OKUMA CORPORATION
    Inventor: Tomohiro Shibata
  • Patent number: 10366018
    Abstract: In a control apparatus which uses a CPU which does not have hardware for memory protection, a function is realized to detect unauthorized writing from a non-safety-related unit program in units of bits, for a safety-related unit data area of a RAM, a safety-related unit register area of an external integrated circuit, and a built-in peripheral I/O register of the CPU. A memory access monitoring unit requests an interrupt process upon detection of a write access of the safety-related unit program permitted to access a safety-related unit region. The interrupt process realizes a function to detect write access from a non-safety-related unit program area by using a program counter of a write access origin retracted to a stack area to judge whether the write access origin is a safety-related unit program or the non-safety-related unit program area, and judge, in units of bits, whether or not there is a change to a safety-related unit region.
    Type: Grant
    Filed: October 16, 2017
    Date of Patent: July 30, 2019
    Assignee: OKUMA CORPORATION
    Inventor: Yoshimasa Egi
  • Patent number: 10357863
    Abstract: An error identification method includes a tool sensor position acquisition stage, a reference block position acquisition stage, a relative position calculation stage, a reference tool position acquisition stage, a position measurement sensor measurement stage, a length compensation value calculation stage, a diameter compensation value acquisition stage, a position measurement stage, a position compensation stage, and a geometric error identification stage. The diameter compensation value acquisition stage acquires a radial direction compensation value of the position measurement sensor with the measured jig. The position measurement stage indexes the rotation axis to a plurality of any given angles and measures respective positions of the measured jig. The position compensation stage compensates the position measurement value at the position measurement stage using the length direction compensation value and the radial direction compensation value.
    Type: Grant
    Filed: April 11, 2017
    Date of Patent: July 23, 2019
    Assignee: Okuma Corporation
    Inventors: Tetsuya Matsushita, Reiji Kanbe
  • Patent number: 10359266
    Abstract: A position measurement method to measure a position of an object in a machine tool includes a tool sensor position acquisition stage, a reference block position acquisition stage, a relative position calculation stage, a reference tool position acquisition stage, a position measurement sensor measurement stage, a length compensation value calculation stage, and a position measurement stage. In the position measurement stage, the measurement position of the object is compensated using a length direction compensation value of a position measurement sensor calculated in the length compensation value calculation stage. The object is measured by the position measurement sensor installed to a main spindle.
    Type: Grant
    Filed: April 7, 2017
    Date of Patent: July 23, 2019
    Assignee: Okuma Corporation
    Inventors: Reiji Kanbe, Tetsuya Matsushita
  • Patent number: 10328543
    Abstract: A machine tool which removal-machines a workpiece by means of a tool includes a retaining device (a workpiece spindle and a tailstock) that retains the workpiece, a support device (an in-machine robot) that supports the workpiece, in order to suppress deflection of the workpiece retained by the retaining device, and a control device that controls driving of the support device by force control having a force as a control target. Specifically, a supporting force by the support device and a machining force by a tool are measured, and the driving of the support device is controlled so that the supporting force is equal to the machining force.
    Type: Grant
    Filed: August 16, 2017
    Date of Patent: June 25, 2019
    Assignee: OKUMA CORPORATION
    Inventor: Shoichi Morimura
  • Patent number: 10310494
    Abstract: A diagnostic result display method in a diagnostic device calculates a diagnostic result by a determination of a predetermined state and a certainty factor of the determination. The diagnostic result display method includes setting preset predetermined colors to predetermined states, setting a preset area of a geometric shape according to certainty factors, and displaying the area of the geometric shape in at least one of the predetermined colors.
    Type: Grant
    Filed: September 12, 2017
    Date of Patent: June 4, 2019
    Assignee: Okuma Corporation
    Inventors: Takumi Hongo, Hitoshi Sumi
  • Patent number: 10307877
    Abstract: A machine tool that machines a workpiece by a tool includes a workpiece spindle device that holds the workpiece in a rotatable manner with a predefined workpiece rotational axis Rw as a center, one or more in-machine robots, and a connecting mechanism that attaches the one or more robots on the machine tool so that the one or more robots move independently from the workpiece, with the workpiece rotational axis Rw serving as a center.
    Type: Grant
    Filed: April 28, 2017
    Date of Patent: June 4, 2019
    Assignee: OKUMA CORPORATION
    Inventor: Shoichi Morimura