Patents Assigned to Okuma Corporation
  • Patent number: 9506736
    Abstract: A measurement system identifies geometric errors by using an initial position measurement step for specifying coordinates and dimensions of a target sphere, and an indexing measurement step for positioning rotary axes according to a plurality of indexing conditions and identifying geometric errors from sensor measured coordinate values corresponding to coordinate values obtained by measuring the target sphere with a sensor of a touch probe. Then, in the indexing measurement step, coordinates of the target sphere can be obtained by simply measuring the target sphere with the sensor only three times, using dimensions of the target sphere obtained in the initial position measurement step.
    Type: Grant
    Filed: March 10, 2015
    Date of Patent: November 29, 2016
    Assignee: Okuma Corporation
    Inventor: Tadahiro Oki
  • Patent number: 9502936
    Abstract: A plurality of coils C1 to Cm that constitutes a whole winding L of each phase is divided into g coil groups G1 to Gg for each phase. Each coil group is, for example, constituted by coils C1 to C4 wound around four polar teeth continuously disposed. The number of turns of respective end coils C1 to C4 of the coil group is less than the number of turns of central coils C2 and C3. Further, the whole winding L includes n partial windings N1 to Nn, in which a coil Cj (j is an integer in the range from 1 to m) is constituted by n sub coils S(1,j) to S(n,j) that are formed by the n partial windings. It is feasible to set a non-integer value as an effective number of turns of a coil when the number of turns of each sub coil is appropriately selected.
    Type: Grant
    Filed: January 29, 2014
    Date of Patent: November 22, 2016
    Assignee: OKUMA CORPORATION
    Inventor: Tatsuya Shizu
  • Patent number: 9457440
    Abstract: A chattering vibration preventing jig is made of metal, and is L-shaped as viewed from the side. A horizontal plate portion has a pair of cuts extending in the short-side direction from an end of the horizontal plate portion. A vertical plate portion has a plurality of screw holes arranged in a line in the long-side direction. Screws slightly longer than lengths of the screw holes are screwed into the corresponding screw holes to abut onto a workpiece. Adhesive is applied to abutment surfaces of the screws that abut onto the workpiece.
    Type: Grant
    Filed: October 8, 2014
    Date of Patent: October 4, 2016
    Assignee: Okuma Corporation
    Inventors: Yoshitaka Fukuda, Ryo Suzuki
  • Patent number: 9459598
    Abstract: Control parameters such as an acceleration/deceleration time constant Tf, a position loop gain Kpf, a velocity loop proportional gain Pvf, and a velocity loop integral gain Ivf, each including respective values assigned to each of a plurality of different inertia values J0˜Jmax, are changed based on an inertia value Jx calculated by an inertia identifying unit and an adjusted control parameter calculated by an automatic control-parameter adjustment unit.
    Type: Grant
    Filed: December 19, 2014
    Date of Patent: October 4, 2016
    Assignee: Okuma Corporation
    Inventors: Kazushige Kigaku, Tomohisa Kameyama
  • Patent number: 9448089
    Abstract: An optical encoder, comprising a plurality of light receiving elements 1-12, receiving light that has passed through or been reflected by a scale having a lattice of pitch P, and outputting four-phase signals that have been respectively offset in phase by an integer number of times 90° (1/4P). 12 light receiving elements being are in the lateral direction (scale longitudinal direction) with gaps between them of P/60 or 2P/60, four arbitrary light receiving elements arranged next to each other in a row all output signals of different phases, and light receiving elements respectively outputting signals of same phase have three lateral widths of 7OP/60, 13P/60 or 20P/60.
    Type: Grant
    Filed: October 24, 2014
    Date of Patent: September 20, 2016
    Assignee: OKUMA CORPORATION
    Inventors: Yasukazu Hayashi, Atsushi Ieki
  • Patent number: 9441942
    Abstract: A stator includes: a core formed by laminating magnetic steel sheets; and an excitation coil and a detection coil which are wound around teeth provided at the core. The core includes a peripheral section which is disposed to surround the rotor and a detection section which is disposed at the interior of the peripheral section and has the teeth. When the magnetic steel sheets are laminated, each of the magnetic steel sheets forming the core includes a portion which constitutes the peripheral section and a portion which constitutes the detection section. The detection section is substantially U-shaped, and both sides of the U-shape become a pair of teeth which form one phase. A base portion of the substantially U-shape of the detection section connects with the peripheral section, and gaps are provided between the peripheral section and a part of the base portion which is the root of the teeth.
    Type: Grant
    Filed: June 28, 2013
    Date of Patent: September 13, 2016
    Assignee: OKUMA Corporation
    Inventors: Soichi Kawamura, Motozumi Yura, Shinji Shibata
  • Patent number: 9381608
    Abstract: When generation of a chatter vibration is detected, a parameter calculation device calculates a first frequency range and a second frequency range. A determination validity is calculated in consideration of a rotation speed detection resolution and a frequency resolution, and based on a ratio of a frequency range of rotational-period forced chatter vibration to a frequency range of regenerative chatter vibration. It is determined based on the determination validity whether the generated chatter vibration is regenerative chatter vibration, rotational-period forced chatter vibration, or flute-passage-period forced chatter vibration.
    Type: Grant
    Filed: January 19, 2012
    Date of Patent: July 5, 2016
    Assignee: Okuma Corporation
    Inventor: Takaaki Tanaka
  • Patent number: 9317028
    Abstract: An electric motor control device for performing tandem control for driving one movable component includes, for each electric motor, a position controller, a speed controller, and a current controller. Further, each electric motor also has a preload controller for adding a preload torque to a torque command Tm calculated by the speed controller, and to a torque command Ts calculated by the speed controller. The preload controller calculates a minimum necessary preload torque for eliminating backlash in accordance with a position of the movable component.
    Type: Grant
    Filed: April 11, 2014
    Date of Patent: April 19, 2016
    Assignee: OKUMA CORPORATION
    Inventors: Takeshi Sakai, Akiyoshi Satake
  • Patent number: 9302362
    Abstract: A door mechanism of a machining center includes a wide door panel, narrow door panels, a pair of upper and lower slide rails into which the wide door panel and the narrow door panels are fitted, and a plurality of motors that serve as drive units for independently driving the wide door panel and the narrow door panels. The wide door panel and the narrow door panels are arranged in line extending across an opening of the machining center to close the opening of the machining center and are slidable in a direction parallel to a width of the opening to open a portion of the opening having a width approximately twice a width of a one of the narrow door panels.
    Type: Grant
    Filed: March 19, 2014
    Date of Patent: April 5, 2016
    Assignee: Okuma Corporation
    Inventors: Tomofumi Tsuchida, Makoto Tomita
  • Patent number: 9266209
    Abstract: 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.
    Type: Grant
    Filed: November 29, 2011
    Date of Patent: February 23, 2016
    Assignee: Okuma Corporation
    Inventors: Toshihiko Murahashi, Hironori Funaguchi
  • Patent number: 9221143
    Abstract: An apparatus includes an external input device that allows setting of the amount of runout and the phase of each cutting edge, a computation device that acquires the rotational phase of a tool and that computes the angular velocity and the phase of vibration of two, X-axis and Y-axis, feed shafts on the basis of the input amount of runout and angular velocity of each cutting edge to generate a feed shaft control signal, and a numerical control device that controls feed in the X-axis and the Y-axis directions. The numerical control device relatively vibrates a workpiece in synchronization with the angular velocity of the tool on the basis of the results of computation performed by the computation device.
    Type: Grant
    Filed: March 11, 2013
    Date of Patent: December 29, 2015
    Assignee: Okuma Corporation
    Inventors: Hiroshi Inagaki, Toshiya Shikama
  • Patent number: 9211624
    Abstract: Determination of chatter vibration is done for a plurality of peak values that appears when frequency-domain vibrational acceleration is obtained through fast Fourier analysis on time-domain vibrational acceleration. In machining at a low rotation speed and machining using a tool with small flute number in particular, a type of chatter vibration that has occurred can be accurately determined, and “natural type vibration” occurring due to friction between a tool and a workpiece and an impact force caused by machining can also be determined.
    Type: Grant
    Filed: April 27, 2012
    Date of Patent: December 15, 2015
    Assignee: Okuma Corporation
    Inventor: Takaaki Tanaka
  • Patent number: 9190946
    Abstract: An acceleration command calculator calculates an acceleration command “as” based on an output torque Tmb of the spindle motor applied when the rotational speed is less than or equal to a base rotational speed and an inertia Jm+Jl of the overall spindle. A switching speed calculator calculates a control mode switching speed Vs based on the acceleration command “as”. A control mode switching switch switches from a speed control mode to a position control mode when the motor speed Vm becomes less than or equal to the control mode switching speed Vs, to stop the spindle at a desired rotational position. The control mode switching speed Vs may be a value calculated using the following equation: Vs=60×(amax×0.5)1/2, where a maximum acceleration that can be achieved at this time is represented by a max.
    Type: Grant
    Filed: March 4, 2013
    Date of Patent: November 17, 2015
    Assignee: OKUMA Corporation
    Inventors: Tomohiro Shibata, Tomohisa Kameyama
  • Patent number: 9188972
    Abstract: A numerical control apparatus includes a program analyzing unit 19 that extracts a command rotational speed of a rotary shaft from a machining program, an optimum rotational speed recording unit 16 that stores a plurality of optimum rotational speeds that are suitable to suppress chattering vibrations, and a command rotational speed substitutability determination unit 17. The command rotational speed substitutability determination unit obtains a substitute rotational speed range that represents a range of a substitutable optimum rotational speed based on the command rotational speed extracted from the machining program, and selects an optimum rotational speed from among the plurality of optimum rotational speeds stored in the optimum rotational speed recording unit, which falls within the substitute rotational speed range, as a command rotational speed to be actually used in processing.
    Type: Grant
    Filed: February 8, 2012
    Date of Patent: November 17, 2015
    Assignee: OKUMA Corporation
    Inventor: Syunji Kido
  • Patent number: 9186765
    Abstract: The monitoring apparatus includes vibration sensors that detect vibration accompanying machining, a rotation detector and a rotation detection section that detect rotation of a main spindle, and a stability limit and vibration distribution calculation section that creates, on the basis of vibration information obtained from the vibration sensors and a rotation speed of the main spindle detected by the rotation detector and rotation detection section, both a stability limit diagram illustrating a relationship between the rotation speed and a stability limit of the machining and a vibration distribution diagram illustrating a relationship between the rotation speed and the vibration, and displays the created diagrams on a monitor in a vertical arrangement.
    Type: Grant
    Filed: October 4, 2011
    Date of Patent: November 17, 2015
    Assignee: Okuma Corporation
    Inventors: Tomoharu Ando, Hiroshi Ueno, Akihide Hamaguchi
  • Patent number: 9174318
    Abstract: A machine tool includes a rotational drive unit that rotationally drives a main spindle to which a tool is attached, a moving unit that relatively moves the tool with respect to the workpiece, and a rotational speed adjustment unit that adjusts a rotational speed of the main spindle by controlling the rotational drive unit. The machine tool also includes a machining start determination unit that determines that machining of the workpiece by the tool is started with the rotational drive unit rotationally driving the main spindle. The rotational speed adjustment unit exponentially raises the rotational speed of the main spindle after reducing the rotational speed to a predetermined rotational speed set in advance, on condition that the machining start determination unit determines that the machining is started, and causes the rotational speed of the main spindle to reach a value of the rotational speed before being reduced.
    Type: Grant
    Filed: June 10, 2014
    Date of Patent: November 3, 2015
    Assignee: Okuma Corporation
    Inventor: Hiroshi Inagaki
  • Patent number: 9170571
    Abstract: A position controller sets a variable friction compensation value which varies in accordance with a change in sliding characteristics by providing a variable friction compensation value calculation unit that includes a sliding torque normalization calculation unit that normalizes a sliding torque at a predefined speed; a compensation value amplifying ratio calculation unit that calculates a compensation value amplifying ratio based on the sliding torque at the normalized speed; and multipliers.
    Type: Grant
    Filed: April 24, 2014
    Date of Patent: October 27, 2015
    Assignee: OKUMA CORPORATION
    Inventors: Masahiro Maeda, Satoshi Eguchi
  • Patent number: 9138848
    Abstract: A vibration suppressing method and a vibration suppressing device are disclosed. After detection of chatter vibration using at least one vibration detecting device, a stable rotation speed for suppressing the chatter vibration is calculated using a stable rotation speed calculating device. A determination device then compares a detection value detected by the vibration detecting device, a predetermined setting value, and/or a current value that is calculated based on at least one of the detection value and the setting value, to a predetermined determination reference value that is previously set. Thereafter, the determination device determines whether or not the stable rotation speed is adopted in accordance with the comparison result, and changes rotation speed of the rotary shaft to the stable rotation speed if the stable rotation speed is adopted.
    Type: Grant
    Filed: October 7, 2011
    Date of Patent: September 22, 2015
    Assignee: Okuma Corporation
    Inventor: Hiroshi Ueno
  • Patent number: 9140581
    Abstract: A position detector includes detection coils for outputting two sinusoidal signals that have phases shifted from each other by 90 degrees; subtractors for eliminating offset components included in output signals DCA and DSC output from the detection coils; an interpolation calculator for converting the two signals DCA and DSC in which the offset components have been eliminated into position information IP; a radius calculator for calculating a root-sum-square of the two signals DC and DS output from the detection coils; correlation calculators for respectively multiplying a fluctuation component RDA of an output from the radius calculator by the signals DCA and DSC in which the offset components have been eliminated; low-pass filters (LPFs) for extracting DC components of output values output from the correlation calculators; and an outputter for outputting offset components including offset displacement fractions based on output values COMDC and SOMDC output from the LPFs.
    Type: Grant
    Filed: July 25, 2011
    Date of Patent: September 22, 2015
    Assignee: Okuma Corporation
    Inventors: Taishi Shimada, Yasukazu Hayashi
  • Patent number: RE45693
    Abstract: A position control apparatus includes a reverse displacement calculation unit configured to calculate a reverse displacement that represents an amount of movement made from a preceding reverse point to a current reverse point by an axis that performs a reversing motion; a reversing-time segmenting number number of consecutive occurrences of reversing motions calculation unit configured to compare the reverse displacement to a predetermined value, and, when the reverse displacement is less than the predetermined value, increase a value of a reversing-time segmenting number of consecutive occurrences of reversing motions, which is a coefficient indicating a number of segments per unit time during a reversing motion, and, when the reverse displacement is greater than or equal to the predetermined value, decrease the value of the reversing-time segmenting number number of consecutive occurrences of reversing motions; and a quadrant inversion compensation unit configured to automatically adjust a quadrant inversio
    Type: Grant
    Filed: January 7, 2013
    Date of Patent: September 29, 2015
    Assignee: OKUMA Corporation
    Inventor: Masaya Minamide