Fujitsu Fanuc Limited

Fanuc Corporation

Yoshinori Kohzai

Yoshiki Fujioka

Naoto Ota

Shigeaki Oyama

Shigeki Kawada

Yoichi Amemiya

Yukio Katsuzawa

Hidetsugu Komiya

Noboru Iwamatsu

Yo Ikebe

Jun Ikebe

Tatsuo Koyama

System for stopping spindle at commanded position

A speed control circuit and position control circuit are connected to a spindle drive motor in a machine tool or the like in order to drive the spindle at a predetermined speed and stop the spindle at a predetermined angular position. When an orientation command is issued while the spindle is being rotated at the predetermined speed by a speed control loop, a speed command signal from a speed command circuit is interrupted, the speed reduced to zero, and an initially set voltage is then employed as a speed command to rotate the spindle by a predetermined amount. Next, a integral value of the actual spindle speed is employed as the speed command to further rotate the spindle by a predetermined amount. When this has been accomplished, a constant bias voltage of a low level replaces the speed command, thereby to rotate the spindle still further by a predetermined amount until a specified portion of the spindle approaches extremely close to the predetermined angular position. At this point a signal, sensed by a magnetic body provided on the specified portion of the spindle and a sensing circuit confronting the magnetic body, is employed as the speed command signal of the speed control circuit, the sensed signal having a gradually decreasing waveform which attains a value of zero when the specified portion of the spindle is stopped at the predetermined angular position. Using this signal gradually decelerates the spindle motor to stop the spindle accurately at the desired angular position.

Spindle orientation control apparatus

A direct current motor comprising: a yoke; an armature; a plurality of main magnetic poles equidistantly spaced around the inner circumference of the yoke, and each of which has a wide portion and a narrow portion, the air-gap between the armature and the main magnetic poles being narrow at the center and ends of the wide portion, and at the center of the narrow portion, and being wide at the intermediate of the wide portion, and at the ends of the narrow portion, and a plurality of interpoles, such as E-shaped interpoles, which are disposed at positions located between the adjacent narrow portions of the main magnetic poles.

Direct current motor

A control circuit for stopping a spindle at a predetermined rotational position, of the type having a position sensor for producing a zero volt signal when a specified point on the spindle arrives at the predetermined rotational position, and for producing a voltage which is positive or negative when the specified point on the spindle is in the vicinity of the predetermined rotational position on either the left or right side thereof. The control circuit includes an orientation control circuit for stopping the spindle drive motor when the output signal from the position sensor attains the value of zero volts, thereby stopping the specified point on the spindle at the predetermined rotational position. The control circuit further includes a position adjustment circuit for adjusting the rotational position, of the specified point on the spindle, at which the output signal from the position sensor crosses the zero volt line. The position at which the specified point is stopped is adjusted by the position adjustment circuit, so that it is possible to correct an error in the stopping position which results from a position sensor mounting error.

Control system for stopping spindle at predetermined rotational position

A system for stopping a spindle, which is provided in a machine tool, in such a manner that a specified point on the spindle is stopped at a predetermined rotational position. The system includes device for detecting the direction of spindle rotation. When the spindle arrives at a region where it is to be controlled in order to stop at the predetermined rotational position, a position deviation signal is applied as the input signal of a speed control loop for controlling the rotation of the spindle. This signal turns the specified point on the spindle to the predetermined rotational position, in the same direction in which the spindle is rotating, on the basis of the direction signal from the detecting means. That is, the specified point on the spindle is rotated to the predetermined rotational position in a direction which is the same as the direction of rotation during tool operation.

A spindle orientation control system having a speed control circuit and a position control circuit for rotating the spindle of a machine tool at a commanded speed and for stopping the spindle at a designated position with a high accuracy, the speed control circuit decelerating the spindle drive motor on the basis of a spindle stopping command. When a predetermined speed has been attained, a counter contained in the position control circuit is triggered by a one-revolution pulse generated whenever the spindle makes one full revolution, whereby the counter begins to count up position pulses which are generated whenever the spindle rotates by a predetermined angle. After a preset predetermined number of pulses have been counted, operation shifts from the speed control mode to a position control mode, and said counter is preset to a number of pulses corresponding to the angle from the present position of the spindle to the desired stopping position. Said pulse number is counted down by the position pulses and, at the same time, a voltage having a level which is proportional to the content of the counter is applied to the spindle drive motor, thereby reducing its rotational speed. When the content of the counter reaches a value of zero, the spindle is stopped at the predetermined position. Adjusting the value preset in the counter makes it possible to correct a spindle stopping position error that results from a difference in the position of the leading or trailing edge of the one revolution pulse, said difference arising because the position of the leading or trailing edge of the one-revolution pulse varies depending upon the direction of spindle rotation.

Spindle orientation control method and apparatus

A motor drive control system for use in a machine tool having spindle and feed shaft motors. If the spindle motor, which is rotating at a constant speed during a machining operation, is subjected to an overload, and consequently experiences a drop in speed, this fact is detected by a detector for detecting the armature current of the spindle motor. The feed shaft motor is slowed down to a predetermined speed if the overloaded condition continues for a prescribed period of time. The feed shaft motor is stopped if an even greater armature current is detected to be flowing due to a continuing overload despite the fact that the feed shaft motor has been slowed to the predetermined speed.

Drive control system for motors

A system for controlling the rotation of a spindle includes a motor, a speed detecting circuit 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 to zero a deviation between the actual speed thereof and a commanded speed, a spindle driven by the motor, and a position control circuit for producing a position deviation signal on the basis of a commanded stopping position and the rotational position of the spindle. The spindle is rotated at a commanded speed by the speed control circuit and is rotationally controlled by an orientation command signal so as to make the position deviation signal zero. The system further includes a proximity switch, which is mounted on the spindle, for detecting the present rotational position thereof, and for producing a detection signal having a value of zero volts when a predetermined point on the spindle has reached a commanded stopping position, and either a positive or negative value depending upon whether the predetermined point on the spindle is immediately to the left or right of the commanded stopping position. The detection signal from the proximity switch serves as the position deviation signal.

Spindle rotation control system

A system employed in a machine tool of the type in which a gear mechanism disposed between the spindle and spindle motor transmits the rotational motion of the motor to the spindle. The system allows the spindle to be brought to a stop at a predetermined rotational position in a shorter period of time when the gear mechanism is set in low gear, that is, while the rotational speed of the motor is being reduced by the gear mechanism as it is being transferred to the spindle. This permits the spindle to be stopped at the predetermined position in the same amount of time which is required when no reduction in speed takes place between the motor and spindle. When the spindle arrives at a region where it is to be controlled in order to stop at the predetermined rotational position, a position deviation signal for guiding the spindle to the position is applied as an input signal to a speed control loop for controlling spindle rotation. The position deviation signal varies in dependence upon the gear ratio of the spindle gear mechanism. Positioning gain, which is obtained by dividing the speed of the spindle motor by an amount of spindle motor rotation that depends upon the position deviation of the spindle; is controlled so that it remains constant regardless of the speed change ratio between the spindle and spindle motor as determined by the gear mechanism.

A direct current motor having E-shaped interpoles, each of the E-shaped interpoles comprising interconnecting members which are made of a non-magnetic material having rigidity and which are tightly and irremovably inserted in gaps between a center pole and side poles of the E-shaped interpole. In the direct current motor according to the present invention, the side poles are mechanically interconnected to the center pole, so that noises generated by the vibration of the side poles are greatly reduced.

Direct current motor having E-shaped interpoles

A tachometer generator comprising a generator section for producing rectangular polyphase alternating voltages having a peak value which is proportional to the speed of the rotor, and a commutator section including contactless change-over switches for successively transferring the alternating voltages from the generator section, and sensors for producing switching signals which actuate the change-over switches in accordance with the rotational position of the rotor of the generator section. In the commutator section the sensors are equivalent in number to the change-over switches and comprise Hall devices arrayed about a rotary shaft which is coupled to the generator section. The alternating voltages which are obtained successively from the coils of the generator section as the rotary shaft rotates, are transferred in order by the change-over switches to produce a speed signal, in analog form; which is proportional to the rotating speed of the rotor. The axially extending width of the rotor is smaller than the axially extending width of the stator, the width of the rotor being approximately 80% that of the stator. A magnetic shield plate is interposed between the generator section and the sensors of the commutator section. The tachometer generator having the above arrangement generates more accurate speed signals and can be reduced in size since the generator and commutator sections are capable of being disposed closer together as a result of the provision of the magnetic shield.

Brushless tachometer generator

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.

Control system for synchronized operation of machine tool motors

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.

Machine tool drive motor control system

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.

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.

Growing community of inventors

Hino, Japan

Yoshinori Kohzai