Abstract: During operation of a machine tool, a motor 14 driving a spindle 17 holding a tool 18 is operated at a commanded speed by a speed control system in accordance with a speed command signal VCMD with the feedback of an actual speed signal TSA. As a stopping command ORCM is issued for stopping the spindle, the spindle is decelerated to a predetermined speed in response to a reference signal output from a constant voltage generating circuit 33. After the deceleration of the spindle to the predetermined speed, as the rotational position of the spindle comes into a region within 180.degree. from a predetermined position, a position offset signal PS', which smoothly crosses the zero level at the position at which the spindle is to be stopped, and which is generated from two signals e.sub.1 and e.sub.2 from a resolver connected to the spindle.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

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.

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.

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.

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.

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.

Abstract: A direct current motor used, for example, in a machine tool, comprising an armature, a plurality of main magnetic poles disposed around the armature having field windings wound thereon, and a plurality of E-shaped interpoles disposed at the intermediate position along the outer circumference of said armature between the adjacent main magnetic poles, each of the E-shaped interpoles consisting of a center pole to which an interpole winding is wound and two side poles, and the width of the gap between the outer circumference of the armature and the end surface of each of the side poles increases from the portion of the gap which is remote from the center pole to the portion of the gap which is adjacent to the center pole.In the DC motor according to the present invention, the linearity of the magnetic flux used for commutation is ensured in a wide range of the armature current, and, therefore, commutating characteristics of the E-shaped interpoles is improved.

Abstract: A positioning control system which has a servo system provided with a position feedback system for detected positional information and a velocity feedback system for detected velocity information of a motor and in which the motor is driven by the servo system in accordance with commanded positional information to position a movable machine part of a numerical-controlled machine. The disparity between the detected velocity of the movable machine part and the detected motor velocity is fed back to the control input side of the motor, thereby suppressing vibration of the movable machine part at the moment of completion of the positioning operation.

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.

Abstract: A direct current motor used, for example, in a machine tool, comprising an armature, n main magnetic poles disposed around the armature, each of the main magnetic poles consisting of a pole core on which a field winding is provided and a pole piece extending along the outer circumference of the armature, and n/2 E-shaped interpoles disposed at the intermediate position along the outer circumference of the armature between the adjacent main magnetic poles, and at the central axis of the armature, the angle spanning from the direct axis, which is electrically perpendicular to the interpole axis, to an end portion of a pole piece of a main magnetic pole is unequal to that from the direct axis to the other end portion of the pole piece of the main magnetic pole.Since the number of the E-shaped interpoles is decreased by half, the direct current motor according to the present invention has simple structure and high torque, and the heat generated by the interpoles is relatively decreased.