Patents by Inventor Yoshiki Fujioka

Yoshiki Fujioka has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4359676
    Abstract: A control system for stopping a spindle at a predetermined rotational position, for driving a spindle in such a manner that a positional deviation between the present rotational position of a specified point on the spindle and a predetermined rotational position at which the specified point is to be stopped, is reduced to zero, thereby to stop the specified point on the spindle at the predetermined rotational position. First and second rotational position sensors are attached to the spindle at first and second specified points thereof, the position at which at least the first rotational position sensor is attached being adjustable. Further provided are changeover means and an orientation control circuit. The first position sensor produces a rotational position deviation signal when a tool is inserted into and withdrawn from a workpiece at the time of a boring operation, and the second position sensor produces a rotational position deviation signal when tools are changed.
    Type: Grant
    Filed: December 12, 1980
    Date of Patent: November 16, 1982
    Assignee: Fujitsu Fanuc Limited
    Inventor: Yoshiki Fujioka
  • Patent number: 4353018
    Abstract: An improved control system for facilitating tapping work in a machining center of the type which performs a variety of machining operations automatically. Control is effected by establishing and maintaining a certain relationship between the operation of a spindle motor which rotates a tap, and the operation of a Z-axis feed motor which transports a table longitudinally of the tap, the table mounting a workpiece. Specifically, the spindle motor and Z-axis feed motor are driven in relation to one another at all times in such a manner that the equation N.sub.s =f.sub.m /P will be satisfied, where N.sub.s (rpm) is the rotational speed of the spindle motor, f.sub.m is the feed speed of the table along the Z-axis, and P is the thread pitch of the tap. Apparatus for controlling the spindle motor includes a control circuit which is adapted to stop the spindle at a prescribed angle of rotation.
    Type: Grant
    Filed: August 20, 1980
    Date of Patent: October 5, 1982
    Assignee: Fujitsu Fanuc Limited
    Inventors: Yoshinori Kohzai, Yoshiki Fujioka
  • Patent number: 4347471
    Abstract: A control system for rigidly stopping the spindle of a machine tool at a prescribed angular position when a tool is to be changed, without the use of a mechanical brake. Provided for this purpose is an orientation control circuit adapted to produce an output signal of zero potential when the spindle is at a prescribed stopping position, and an output signal of a potential proportional to the amount of angular deviation when the spindle is displaced from the prescribed stopping position. To stop the spindle at a prescribed stopping position, the output signal from the orientation control circuit is delivered in place of a speed command signal to a speed control loop of the type which limits to zero the difference between the speed command signal and a speed feedback signal. When the spindle is at rest, the feedback function of the speed control loop holds the rotary shaft of the spindle motor rigidly at the stopping position as if a mechanical brake were applied thereto.
    Type: Grant
    Filed: December 14, 1979
    Date of Patent: August 31, 1982
    Assignee: Fujitsu Fanuc Limited
    Inventors: Yoshinori Kohzai, Yoshiki Fujioka, Naoto Ota
  • Patent number: 4347470
    Abstract: A spindle orientation control apparatus having a motor for driving a spindle, speed control means for rotating the spindle at a speed in accordance with a command speed, and position control means for stopping the spindle at a commanded stopping position. The apparatus is further provided with stopping position command means for digitally instructing the spindle stopping position, a position sensor, error monitoring means for monitoring an error between the commanded stopping position and the actual rotational position of the spindle and for generating a signal when the error attains a predetermined value, and means for generating a signal indicative of an orientation speed. When the apparatus is in a spindle orientation control mode, the spindle is speed-controlled so as to rotate at the orientation speed until the error monitoring means generates said signal, and is position-controlled after the generation of the signal so as to reduce the error to zero.
    Type: Grant
    Filed: February 20, 1981
    Date of Patent: August 31, 1982
    Assignee: Fujitsu Fanuc Limited
    Inventors: Yoshinori Kohzai, Yoshiki Fujioka, Naoto Ota
  • Patent number: 4345192
    Abstract: A control system for stopping a spindle at a prescribed rotational position having a position control loop for driving a spindle so that a positional deviation between the present rotational position of a specified point on the spindle and a predetermined rotational position at which the specified point is to be stopped, is reduced to zero to stop the specified point on the spindle at the predetermined rotational position. Fine and coarse voltage signals are utilized for the final positioning process.
    Type: Grant
    Filed: September 25, 1980
    Date of Patent: August 17, 1982
    Assignee: Fujitsu Fanuc Limited
    Inventors: Yoshinori Kohzai, Yoshiki Fujioka, Naoto Ota
  • Patent number: 4342950
    Abstract: A system for controlling the rotation of a spindle which includes motor, a speed detector for detecting the speed of the motor and for producing a signal indicative of the actual speed thereof, a speed control circuit for controlling the motor so as to narrow a deviation between the signal indicative of the actual motor speed and a command speed signal, a spindle which is driven by the motor, and an orientation control circuit for producing a position deviation signal on the basis of the rotational position of the spindle and a commanded stopping position, wherein the spindle is rotated at a commanded speed by the speed control circuit and rotationally controlled in response to an orientation command signal so as to reduce the position deviation signal to zero.
    Type: Grant
    Filed: September 25, 1980
    Date of Patent: August 3, 1982
    Assignee: Fujitsu Fanuc Limited
    Inventors: Yoshinori Kohzai, Yoshiki Fujioka, Naoto Ota
  • Patent number: 4330832
    Abstract: A method of, and apparatus for, controlling the feed rate of a cutter in a machine tool of the type in which a spindle is rotated by an electric motor having operating regions of constant torque and output characteristics so as to render constant the circumferential speed of a workpiece while the workpiece is subjected concurrently to a machining operation by moving a cutter into contact therewith. The apparatus includes mechanism for computing the maximum cutter feed rate, the circumferential speed V.sub.c of the workpiece, the cutting width d of the cutter and the maximum cutting quantity Q.sub.max which is decided by the maximum power P.sub.max of the motor, mechanism for computing a spindle speed N.sub.s from the circumferential speed V.sub.c and the outer diameter D of the workpiece, mechanism for comparing the magnitudes of a base speed N.sub.b and the spindle speed N.sub.s, where the base speed N.sub.
    Type: Grant
    Filed: March 7, 1980
    Date of Patent: May 18, 1982
    Assignee: Fujitsu Fanuc Limited
    Inventors: Yoshinori Kohzai, Shigeki Kawada, Yoshiki Fujioka
  • Patent number: 4300079
    Abstract: A DC motor control system which has means for detecting the rise and fall of a drive command signal to generate an ON ACCELERATION/DECELERATION signal and means for generating a current limit signal for driving a DC motor by the ON ACCELERATION/DECELERATION signal to produce a rated output and for driving the DC motor to produce an output 1/n times the rated output when the DC motor is switched from an acceleration state to a stationary state. When the DC motor is accelerated or decelerated by the drive command signal, a current for obtaining the rated output is applied to the armature of the DC motor and, in the stationary state, even when a load on the DC motor is maximum a current for obtaining an output 1/n times the rated output is applied to the armature of the DC motor to reduce the output of the large-output DC motor, thereby providing an enlarged constant output DC motor range.
    Type: Grant
    Filed: April 23, 1979
    Date of Patent: November 10, 1981
    Assignee: Fujitsu Fanuc Limited
    Inventors: Shigeki Kawada, Yoshiki Fujioka, Naoto Ohta, Yasuo Takahasi
  • Patent number: 4284932
    Abstract: A system for a DC motor associated with a field winding and driven by using a three-phase anti-parallel thyristor bridge circuit, comprising a first means for controlling an armature current I.sub.a flowing through an armature of the DC motor, and; a second means for controlling a field current I.sub.f flowing the field winding by obtaining the feedback values of a voltage E.sub.a of the armature and the field current I.sub.f and by changing the maximum level of the current I.sub.f in accordance with a three-phase alternating voltage V.sub.ac applied to the three-phase anti-parallel thyristor bridge circuit. In the system, when the three-phase alternating voltage V.sub.ac decreases to a value lower than a predetermined value V.sub.o, the field current I.sub.f are decreased so that the armature voltage E.sub.a is decreased.
    Type: Grant
    Filed: September 18, 1979
    Date of Patent: August 18, 1981
    Assignee: Fujitsu Fanuc Limited
    Inventors: Shigeki Kawada, Yoshiki Fujioka, Naoto Ohta
  • Patent number: 4284939
    Abstract: A device for detecting opposite phases and an open phase in an input three-phase voltage for a DC motor, wherein the input three-phase voltage is rectified by a three-phase bridge circuit and supplied to the armature of the DC motor. The input three-phase voltage is supplied to the three-phase bridge circuit when the maximum level is equal to or less than the reference voltage, while the input three-phase voltage is not supplied to the bridge circuit when the maximum level is greater than the reference voltage. In this case, both opposite phases and an open phase can be detected by using a common device. In addition, only two phases, such as U- and W-phases, are used for detecting opposite phases and an open phase no matter how these phases may be generated in any phase such as U-, V- or W-phase of the input three-phase voltage. As a result, the device is small in size, simple in electrical construction and low in cost.
    Type: Grant
    Filed: September 18, 1979
    Date of Patent: August 18, 1981
    Assignee: Fujitsu Fanuc Limited
    Inventors: Shigeki Kawada, Yoshiki Fujioka, Naoto Ohta, Yutaka Koiwai
  • Patent number: 4268781
    Abstract: An actual speed N of a DC motor and an armature current Ia are detected to detect the motor output N.times.Ia. The motor speed is changed so that the detected motor output may not exceed a predetermined value. The spark generation of the motor brush is prevented when an over load is applied to the motor.
    Type: Grant
    Filed: November 11, 1977
    Date of Patent: May 19, 1981
    Assignee: Fujitsu Fanuc Limited
    Inventors: Shigeki Kawada, Shigeaki Oyama, Yoshiki Fujioka, Mitsuhiko Hirota, Toyohiko Nishimori
  • Patent number: 4268782
    Abstract: A system for controlling DC motors of the type employing permanent magnets as field poles. The firing phase angle of a thyristor is controlled in response to an error signal representative of an error between a commanded motor speed and an actual motor speed. For preventing demagnetization of the permanent magnets due to the armature reaction, the clamp level of the error signal is changed in accordance with the actual motor speed.
    Type: Grant
    Filed: September 7, 1978
    Date of Patent: May 19, 1981
    Assignee: Fujitsu Fanuc Limited
    Inventors: Shigeki Kawada, Yoshiki Fujioka, Mitsuhiko Hirota, Naoto Ohta
  • Patent number: 4207504
    Abstract: A speed detector produces a spindle speed signal proportional to the revolving speed of a spindle. A specified position detector provides a specified position signal when the spindle assumes a specified rotational position. A spindle motor speed control unit controls the spindle motor so that the motor speed agrees with a speed command. When spindle orientation is requested, one integrator circuit responds to the specified position signal to integrate the spindle speed signal. The output from the integrator circuit is applied to the speed control unit in place of the speed command.
    Type: Grant
    Filed: September 7, 1978
    Date of Patent: June 10, 1980
    Assignee: Fujitsu Fanuc Limited
    Inventors: Shigeki Kawada, Yoshiki Fujioka, Mitsuhiko Hirota