Patents Assigned to Okuma Corporation
  • 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
  • Publication number: 20190163164
    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: Application
    Filed: October 24, 2018
    Publication date: May 30, 2019
    Applicant: OKUMA CORPORATION
    Inventor: Takumi HONGO
  • Patent number: 10302511
    Abstract: A method for determining a cogging torque may include applying a substantially constant rotation torque to an output shaft of a motor without electrically energizing the motor; detecting, an angle of rotation of the output shaft of the motor at each of a plurality of angles of rotation; calculating an angular acceleration of the motor at each of the plurality of angles of rotation by second order differentiating the angle of rotation; calculating a measured torque value at each of the plurality of angles of rotation by multiplying the angular acceleration by a moment of inertia of a rotor in the motor; obtaining a measured torque waveform of the measured torque value at each of the plurality of angles of rotation as a function of the plurality of angles of rotation; and calculating a cogging torque waveform based on a frequency of the measured torque waveform.
    Type: Grant
    Filed: December 9, 2015
    Date of Patent: May 28, 2019
    Assignee: OKUMA CORPORATION
    Inventor: Tatsuya Shizu
  • Publication number: 20190146454
    Abstract: An operating state display device displays an operating state of a feed axis in a machine tool including the feed axis. The feed axis linearly moves a moving body via a ball screw with a servomotor. The operating state display device includes a passage number count unit, a use frequency calculation unit, and a display unit. The passage number count unit preliminarily divides an operating range of an axis operation of the feed axis into a predetermined number of sections and counts passage numbers of the moving body in the respective sections. The use frequency calculation unit calculates frequencies of use in respective classified types of the axis operation in each of the sections based on the counted passage numbers. The display unit displays the calculated frequencies of use in the respective classified types on a monitor in a predetermined aspect.
    Type: Application
    Filed: October 24, 2018
    Publication date: May 16, 2019
    Applicant: OKUMA CORPORATION
    Inventor: Takumi Hongo
  • Patent number: 10265818
    Abstract: In a machine tool, when machining is in a steady zone, a rotation phase of a main spindle at the time of measurement in the N-th sampling is calculated, and the calculated rotation phase and the measurement value are recorded in a recording section so as to be associated with each other. The measurement and calculation of the rotation phase of the main spindle at the time of each measurement are continued for plural times of rotations of the main spindle, and thus the measurement values are obtained at various rotation phases, whereby change in drive force during one rotation of the main spindle is finally calculated.
    Type: Grant
    Filed: August 9, 2017
    Date of Patent: April 23, 2019
    Assignee: Okuma Corporation
    Inventor: Takaaki Tanaka
  • Patent number: 10245697
    Abstract: A method for controlling a temperature adjustment system of a machine tool is provided. With the method, a temperature rise value ?Tk of a main spindle device after stopping of rotation of a main spindle is obtained by using a reference temperature measured by a machine body temperature sensor mounted in a portion other than the main spindle device of a machine tool to calculate an estimated temperature yk. Therefore, as compared to a conventional method based only on a temperature of a cooling medium, supply of the cooling medium by a cooling device can be stopped or an operation of the cooling device can be switched from a first mode to a second mode without deteriorating machining accuracy in the main spindle device, thereby efficiently reducing power consumption.
    Type: Grant
    Filed: October 13, 2015
    Date of Patent: April 2, 2019
    Assignee: Okuma Corporation
    Inventors: Eisuke Sogabe, Seiei Yamamoto
  • Publication number: 20190084112
    Abstract: A numerical control device for a machine tool controls a machine tool having a main spindle for attaching a tool, a table holding a workpiece and a jig, three translational axes, and one or more rotation axis. The numerical control device includes an axis-dependent deformation error estimation unit, an input unit, a gravitational deformation estimation unit, a correction value calculation unit, and an addition unit. The correction value calculation unit calculates a correction value of the translational axes and/or the rotation axis with respect to an error of a position and/or a posture of the tool with respect to the workpiece, based on an estimated value of an axis-dependent deformation error, an estimated value of a gravitational deformation error, and command values. The addition unit adds the correction values to the command values.
    Type: Application
    Filed: August 27, 2018
    Publication date: March 21, 2019
    Applicant: OKUMA CORPORATION
    Inventors: Takuya KOJIMA, Tetsuya MATSUSHITA
  • Publication number: 20190079489
    Abstract: A machining simulation apparatus performs a machining simulation in a machine tool by controlling a relative position between a tool model and a material model to perform a machining of the material model with the tool model. The machining simulation is performed with an input of at least one of a position command and a position detection value. The position command and the position detection value are obtained from the machine tool as log data corresponding to a time. A result of the machining simulation is displayed.
    Type: Application
    Filed: August 27, 2018
    Publication date: March 14, 2019
    Applicant: OKUMA CORPORATION
    Inventors: Keishi NATSUHARA, Daichi TATEBE, Katsunori KUNIMITSU
  • Patent number: 10228677
    Abstract: 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.
    Type: Grant
    Filed: April 13, 2016
    Date of Patent: March 12, 2019
    Assignee: Okuma Corporation
    Inventor: Tomoharu Ando
  • Patent number: 10209107
    Abstract: A geometric error identification method of multi-axis machine tool includes a measuring step of indexing a position of a target ball mounted on one of a main spindle and a table into a plurality of angles around an rotation axis, and measuring the position of the target ball at respective indexed positions by using a touch probe mounted on the other one of the main spindle and the table, a geometric error calculation step of calculating a geometric error from the measured position of the target ball, an ellipse-expression calculation step of calculating an ellipse approximate expression by an arc trajectory measured by operating the rotation axis, and an error correcting step of calculating and correcting a scaling error of translation axes from the calculated ellipse approximate expression.
    Type: Grant
    Filed: October 27, 2014
    Date of Patent: February 19, 2019
    Assignee: Okuma Corporation
    Inventor: Tadahiro Oki
  • Patent number: 10180164
    Abstract: A resolver for a rotation position detection device comprises a rotor portion having a resin gear having a hole formed at a center portion thereof through which a stationary shaft passes, and a rotor core connected to the resin gear; and a stator portion having the stationary shaft, an excitation wiring and a detection wiring, a back core, and a resin housing, wherein the excitation wiring and the detection wiring are arranged around the stationary shaft at a constant distance from the stationary shaft in a diameter direction, the back core is adjacent to or in contact with the stationary shaft, and the resin gear has a shape whose central portion projects in the shaft direction so as to be in contact with the back core.
    Type: Grant
    Filed: September 9, 2016
    Date of Patent: January 15, 2019
    Assignee: OKUMA CORPORATION
    Inventors: Shinji Shibata, Yasunori Kawakami