US2817049A - Ward-leonard control for wire spooler - Google Patents

Description

Dec. 17, 1957 H. A. DICKERSON 2,

WARD-LEONARD CONTROL FOR WIRE SPOOLER Filed Nov. 10, 1953 WDM Drawing Machine To Drawing Machine Motor Field Rheoiot INVENTOR Henry A. Dickerson.

ATT

United States Patent 2,817,049 WARD-LEONARD CONTROL FOR WIRE SPOOLER Henry A. Dickerson, Snyder, N. Y., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pro, a corporation of Pennsylvania Application November 10, 1953, Serial No. 391,338

13 Claims. (Cl. 318146) My invention relates to electric systems of control, and

more particularly to systems of control for controlling the operating characteristics of a direct current motor and generator connected in a loop circuit.

A particular application of my system of control is for the drive of a wire drawing machine spooler, which is a device located at the output end of a wire drawing machine for taking the finished wire from the wire drawing machine at a definite value of tension and winding it in even layers of uniform tightness on a spool. My invention is not limited to this application but since the merits of my invention may be effectively explained in connection with the application mentioned, the disclosure will proceed with the particular application in mind.

To better understand the problems involved, a very brief description of the wire drawing machine in relation to the spooler drive may be helpful.

In a wire drawing machine the wire is pulled through dies with successively smaller holes by powered capstans to reduce the Wire in cross section and increase it in length. The capstans are located between the various dies so that they pull the wire from one die and supply it to the next die in line. The tension required is developed by the wire friction of one or more turns about the capstan. The last of the capstans pulls the wire from the last die and delivers the wire to the spooler drum.

While the take-away tension between the last capstan and spooler may vary over a fair range, a departure too great from the desired range can cause trouble. If the spooling tension is too high the wire pulls too tightly on the spool, causing a turn to slip down between turns of a previous layer and lock in. This prevents proper unwinding of the wire from the spool, and causes wire breakage and scrapping of the spool in many instances.

If the wire tension between capstan and spooler is too low, the capstan cannot develop sufficient pull on the entering wire to pull it through the finish die. Slip will then occur on thefinish capstan causing the wire to jump and chatter which may cause the wire to snarl and break.

One broad object of my invention is the provision of a system of control for a motor generator loop to provide the proper torque characteristics for the motor, to incidentally provide for the application had in' mind a proper tension in the wire between the last capstan of a wire drawing machine and the spooler drum.

Another broad object is the provision of proper wire tension during spool build-up, drawing machine acceleration and drawing machine deceleration.

It is also an object of my invention to provide proper torque on the spooler motor when at Zero speed to provide proper stall tension.

The only mechanical connection between the separately powered spooler drive and the wire drawing machine .is throughthe'wire being spooled. To correlate the speed vI provide. electro-mechanical interconnections between the drives to match the spooler speed, during normal running and during acceleration and deceleration, to the speed of the drawing machine. Such correlation alone is, however, not enough because wire sizes vary, the starting and stopping may occur when the spool is anywhere between an empty spool and a full spool, the accelerating rates may be adjustable, and the spool capacity may be changed.

One broad object of my invention is the provision in an electric control for a direct current motor to compensate for changes of inertia, accelerating rate, IR drop and speed change.

Other objects of my invention will become more apparent from a study of the following specification and the accompanying drawing, in which the single figure is a diagrammatic showing of my invention as applied to a motor operating a load, as a wire spooler.

The generator is provided with a shunt field winding SF and a voltage regulating field winding RF. This regulating field winding RF is connected in a loop circuit with the armature of the pilot generator and the armature of the reel, or main generator G. The connection is such that when there is a difference in the output voltages between these two generators, a current flows in the regulating field winding RF in such a direction to cause the main generator voltage to follow the pilot generator voltage.

In the drawing IM represents the constant speed motor for driving the generator G, which generator G is connected in a loop circuit with the motor M driving the spool S for receiving the wire W from the last capstan C of the wire drawing machine WDM. A pilot generator PG is mechanically coupled to the last capstan C. Since the pilot generator PG is excited at a selected fixed value by its field winding PF connected as shown through the rheostat R directly to the fixed voltage direct current supply buses 1 and 6, its voltage output is substantially directly proportional to the speed of the last capstan C of the wire drawing machine WDM.

The motor for driving the spool S is excited by its field winding MF which is subject to the output of the magnetic amplifier MA. This magnetic amplifier does, however, not take over the control of the field winding until its output is in excess of a selected value determined by the direct current voltages supplied through rheostat 2 from the buses 1 and at the direct current terminals of the full-wave rectifier PR. The circuit for field winding MF from the buses 1 and 6 may be traced from bus 1 through rheostat 2, terminal 3, field winding MP through the self-exciting windings 4 and 5 of the magnetic amplifier MA to bus 6.

To more readily understand my contribution to the art, a brief explanation of the starting and operating functions of the showing in the figure may be helpful.

To start the system, assuming the generator G is running at full speed, the start push button switch 8 is depressed whereupon a circuit is established from bus 1 through the stop switch 7, the upper contacts of start switch 8, the actuating coil 9 of the dynamic braking contactor DB to bus 6. Operation of the dynamic braking contactor closes contacts 11 and opens contacts 12 to open the circuit of the dynamic braking resistor DBR. Closure of contacts 11 establishes a circuit from the upper contacts of the start switch 8, through the actuating coil 10 of :contactor SM, the contacts 11, the lower contacts 13 of the start switch 8 to bus 6. The contacts 13 are in parallel to the broken wire switch BWS and other safety switches, not shown. The contactor SM after it operates holds itself in through contacts 14 and closes contacts 16 and 18 simultaneously and a moment later closes contacts 19 to efiect the starting of the wire drawing machine a moment after the spooler motor has subjected the wire to tension. 111 case of wire breakage switch BWS opens action .2 to stop the system. The closure of contacts 18 closes the circuit shown for the brake coil to decouple the brake from its brake drum to permit the motor M to start the spool S.

The closure of contacts 16 establishes a circuit from the upper terminal of generator G through contacts 16, the armature of motor M, resistor 17 to the lower terminal of the generator G. The motor M having its field MF excited will, if the voltage ofgenerator G is up, place some torque on the spool shaft. The voltage of generator G is, however, dependent on the regulating effect of the pilot generator PG and the excitation the regulating field RF receives from the generators G and PG which are in a loop circuit with the regulating field RF.

In a simple loop circuit for the regulating field winding RF as just explained certain steady state and dynamic errors exist, the magnitudes of such errors depending on system gain, regulating circuit time constant, power loop circuit IR-drop, and the rate of change of the pilot generator voltage.

In my control system I use compensating voltage in the loop circuit produced by the flow of controlled external current through a low resistance resistor connected in the loop circuit of the regulating field RF. In addition, this system I interconnect with the regulating apparatus of the tension winder to ipro'duce a selected stall tension and/ or spooler jogging.

Stall tension This function is achieved when the motor M isat, or near, zero speed and the constant tension regulator, namely the controlled magnetic amplifier control, operating on the field MP, is ineffective because of the low value or absence of E. M. F. from motor M. For this condition the pilot generator voltage, being proportional to the wire speed, will be at or near zero and the voltage of generator G, being made tomatch the voltage of the pilot generator 'by the action of the reg-ulatingfield winding RF, will be too low to cause an effective current to how in the armature loop circuit of the motor M and generator G. With the control I provide, a current is caused to flow from terminal 1th through the closed contacts 101 of the decelerating contactor Dec, the adjustable resistor 102, conductor 1G3, resistor 104, which resistor 104 may be of relatively low resistance value, through the back contacts 105 of the decelerating contactor Dec, to the terminal 106. This flow of current through resistor 104 produces a voltage drop. This voltage drop, being in the regulator circuit, appears as an E. M. F. to the field RF and a current flows in. this field winding until the voltage of generator G balances the voltage appearing across the resistor 104. The generator voltage is then strong enough to cause an effective current to flow in the armature of motor M. This current interacting with the minimum spooler motor field excitation provided by field winding MF :produces a motor torque to provide stall tension and/ or spooler jogging. The magnitude of the torque can be varied by adjustment of tap 167 on -the stall tension rheostat 1132.

It should be noted that tap 137 is ganged with the rheostat of the pattern winding rheostat in such a manner that when the excitation of the pattern winding i increased the stall tension is increased also. By proportioning the magnitude of the stall current so that its effect in the tension regulator control is always less than that of the pattern winding, the regulator (the magnetic amplifier regulator) will remain at the minimum output condition. This is desirable for'the following reasons.

(1) If the tension regulator saturated when the stall current was increased the stall torque would be increased heyond desirable limits when the motor field was increased.

(2) Minimum regulator outputis a desirable condition at the beginning of the accelerating period that follows the application of stall tension.

(3) Minimum field strength allows a maximum stall current to flow for a given stall torque. This allows effective IR compensation as outlined in the following:

IR c0mpcnsati0n.The stall voltage produced across the resistor 104 by the external current is maintained during the accelerating and running periods. Since this voltage can cause a stall current to flow that is slightly less in magnitude and in step with the running current controlled by the pattern field strength it furnishes an effective IR compensation.

Inertia c0mpcnsation.During accelerating or decelerating periods the tension regulator of the standard spooler scheme changes the spooler motor armature current to increase or decrease motor torque to provide inertia compensation to accelerate or decel-erate the spooler and its load. This change in controlled armature current changes the IR drop in the spooler motor armature loop. The proposed scheme, using additional contacts on the accelerating and decelerating relays provided for the tension regulator, in conjunction with variable resistances in a circuit parallel to the stall tension adjusting rheostat, increases or decreases the voltage appearing across the resistor 104 to provide improved IR compensation during these periods when inertia compensation is required. Also, if the compensating voltages are made higher than required for IR compensation alone, they will, (1) compensate for the inductive time lag in the regulator field RF of the generator and, (2) cause the spooler generator output voltage to lead a change in pilot generator voltage and thereby allow the tension regulator operating on the motor field to be more effective during the periods when inertia compensation is required.

Assuming that the voltage of generator G is such that the motor M accelerates, as it does so, the accelerating contactor is eneregized by a circuit that may be traced from bus 1 through contacts 20 of the acceleration switch AS, actuating coil it of the accelerating contactor Act: to bus 6.

This contactor Acc closes its contacts 188 to alter the regulating component on field RF in response to acceleration by connecting an adjustable resistor 109 in parallel to resistor I92. Contactor Acc also closes contacts 22 and 23 to place a voltage across the inertia compensation potentiometer P by a circuit that may be traced from bus 1 through adjustable resistor 24, contacts 22, potentiometer P, contacts 23 to bus 6. This energizes windings 2% and 3t) cumulatively with respect to the pattern windings 33 and 37. to increase the torque of the motor M to maintain wire' tension.

When the decelerating contactor Dec is energized by closure of contacts 25, this contactor Dec closes contacts as and 27, to energize potentiometer P with reverse polarity, and closes contacts I10 and opens contacts 101 and 105 to reverse the control effect for the regulating field RF from the terminals and 106 through the rheostat 111.

The tap 28 connects the inertia compensating control windings 29 and 30 of the magnetic amplifier to the potentiometer P. This energizes windings 29 and 30 so as to reduce the torque of motor M. The pattern field windings 32 and 33 are differential with respect to the main windings 39 and 40, and are connected directly to buses 1 and 6 through rheostat 31.

The control windings 34 and 35 are connected directly across resistor 17 to produce a control effect cumulative with respect to main windings 39 and 40, and proportional to armature current.

The circuit for the main windings of the magnetic amplifier may, for one half wave of alternating current, be traced from the upper terminal of the secondary of transformer T through rectifier 36, field winding MF from left to right, self-exciting feed-back windings 4 and 5 which are cumulative with respect to-windings' 39' and 40, bus 6, rectifiers 37 and 38, and winding 39 to the lower terminal of transformer T.

Anti-hunt windings 44 and 45 on the magnetic amplifier MA are connected in shunt with the series connection of windings 4 and 5 and field winding MF, difierentially with respect to the main windings 39 and 40, for stabilizing operation of the amplifier.

For the second half wave the circuit is from the lower terminal of the secondary of transformeg T through main winding 40, rectifiers 41 and 42, field winding MF from left to right through the feed-back windings 4 and 5, bus 6, and rectifier 43 to the upper transformer terminal.

During normal operation the voltage of the generator G is matched against the voltage of the pilot generator PG to regulate the voltage applied to the armature of motor M. Tension is maintained by magnetic amplifier MA, which increases the voltage applied to the field MP in response to an increase in energization of windings 34 and 35 upon an increase in armature current and thus reduces the tension on the wire, restoring the armature current to normal. The value of current for which the amplifier MA is set is determined by the pattern windings 32 and 33, and is increased and decreased by the inertia compensation windings 29 and 30 during acceleration and deceleration respectively, so as to maintain wire tension.

From the control disclosed, it is apparent that-I have provided, among other novel and valuable features constituting part of my invention, for:

(1) The elimination of rotating machines heretofore used for similar purposes.

(2) Adjustable stall tension at standstill and low spooling speeds when the tension regulator is inefiective.

(3) Effective power circuit IR compensation during running periods furnished by the same control components that provide stall tension.

(4) Additional compensation during accelerating and decelerating periods for increased IR drops, inductive time lags and inertia compensation.

While I have shown but one embodiment and one application of my invention, modifications may readily be devised by those skilled in the art, after having had the benefit of my disclosure, without departing from the spirit of my invention.

I claim as my invention:

1. In a Ward-Leonard control including a generator and a motor connected in a loop circuit, in combination, a field winding for the motor, an impedance in the loop circuit of the motor and generator, a magnetic amplifier for controlling the energization of the motor field winding, a control winding, responsive to the motor armature current, for said magnetic amplifier, a pilot generator, a generator field winding, a control loop circuit including the armature of the generator, the generator field winding, and the armature of the pilot generator, and means for providing a voltage drop in said control loop circuit to alter the excitation of the generator field winding.

2. In a Ward-Leonard control including a generator and a motor connected in a loop circuit, in combination, a field winding for the motor, an impedance in the loop circuit of the motor and generator, a magnetic amplifier for controlling the energization of the motor field winding, a control winding, responsive to the motor armature current, for said magnetic amplifier, a pilot generator, a generator field winding, a control loop circuit including the armature of the generator, the generator field winding, and the armature of the pilot generator, a resistor in said control loop circuit, and means for providing a voltage drop in said control loop circuit across said resistor to alter the excitation of the generator field windmg.

3. In a Ward-Leonard control including a main generator and main motor having their armature windings connected in a loop circuit, in combination, a field winding for the generator, an impedance, a pilot generator, operable in response to the speed of the main motor, having its armature winding connected in a control loop 6 circuit with the main generator armature, the generator field winding, and said resistance, and means for producing a voltage drop across said impedance from an external voltage source.

4. In a Ward-Leonard control including a main generator and main motor having their armature windings connected in a loop circuit, in combination, a field winding for the generator, an impedance, a pilot generator, operable in response to the speed of the main motor, having its armature winding connected in a control loop circuit with the main generator armature, the generator field winding, and said resistance, means for producing a voltage drop across said impedance from an external voltage source, a field winding for said motor, and control means for energizing said motor field winding as a function of the armature current of the motor and as a function of the voltage drop from said external source produced in said impedance.

5. In a control for a direct-current motor having an armature, a main generator having an armature connected in circuit with the motor armature to supply the principal energy to energize the motor armature, voltage producing means responsive to motor speed connected across said main generator, and field winding means on said main generator including a difierential field winding connected in series with said voltage producing means across'sai main generator.

6. In a control for a direct-current motor, a main generator having an armature circuit connected to energize the motor armature, voltage producing means responsive to motor speed connected across said main generator, field winding means on said main generator including a dilferential field winding connected in series with said voltage producing means across said main generator, impedance means connected in series with said voltage producing means across said main generator, and circuit means connected with said impedance means for applying an electrical quantity thereto.

7. In a control for a machine operated by a directcurrent motor having an armature winding and a field winding, the combination of a generator having an armature winding connected to the motor armature winding, a magnetic amplifier having a direct current output circuit connected to the motor field winding, control winding means on said magnetic amplifier, adjustable impedance means connected to said control winding, and acceleration switch means operable to effect acceleration and deceleration of said machine and connected to said impedance means to reversibly energize said impedance means.

8. In a control for a machine operated by a directcurrent motor having an armature winding and a field winding, the combination of, a generator having an armature Winding connected to the motor armature winding, voltage producing means connected with said motor for producing a voltage proportional to motor speed, circuit means including a differential field winding on said generator and an impedance device connecting said voltage producing means across said generator, a magnetic amplifier having a direct-current output circuit connected to said motor field winding, control winding means on said magnetic amplifier, adjustable impedance means connected to said control winding means, adjustable impedance means connected to said impedance device, means mechanically connecting both said adjustable impedance means, and means for energizing both said adjustable impedance means.

9. In a control for a machine operated .by a direct-current motor having an armature winding and a field winding, the combination of, a generator having an armature winding connected to the motor armature winding, voltage producing means connected with said motor for producing a voltage proportional to motor speed, circuit means including a differential field winding on said generator and an impedance device connecting said voltage producing means across said generator, a magnetic "amplifier having a. direct-current output circuit connected to said motor field winding, control winding means on said magnetic amplifier, adjustable impedance means connected to said controlwindingmeans, adjustable impedance means'connected to said impedance device, means mechanically connecting both said adjustable impedance means, means for energizing both'said adjustable impedance means and acceleration switch means operable 'to eifect acceleration and deceleration of said machine and connected to said impedance means to reversibly energize said first-named adjustable impedance means.

10. Ina direct-current motor control, a motor'having an armature winding and a field winding, a main generator having an armature winding and field winding means including adiiferential field winding, circuit means connecting the generator armature-winding to the motor armature winding, a pilot-generator connected to and driven by said motor, an impedance device, circuit means connecting said differential field winding, said pilot generator and said impedance device across said generator armature winding, magnetic amplifier means having a direct-current output circuit connected to energize said motor field winding and having control winding means, andcircuit meansconnected with said impedance device and with said control Winding means for simultaneously affecting a control thereof.

11. In a direct-current motor control, a motor having an armature winding and a field winding, a main generator havingan armature winding and field winding means including a difierential field winding, circuit means connecting the generator armature winding to the motor armature winding, a pilot generator connected to and driven by said motor, an impedance device, circuit means connecting said differential field winding, said pilot generator and said impedance device across said generator armature winding, magnetic amplifier means having a direct-current output circuit connected to energize said motor field winding and having control winding means, said control winding means comprising at least two control windings, circuit means connecting one control winding to said motor armature to be energ zed in dependence of motor armature current, an adjustable impedance connected to the other control winding, a second adjustable impedance connected to said impedance device, and means mechanically connecting said firstmentioned and said second adjustable impedances to provide simultaneous adjustment.

12. In a direct-current motor control, a motor having an armature winding and a field Winding, a main generator having an armature winding and field winding means including a differential field winding, circuit means connecting the generator armature winding to the motor armature winding, a pilot generator connected to and driven by said motor, an impedance device, circuit means connecting said differential field winding, said pilot generator and said impedance device across said generator armature winding, magnetic amplifier means having a direct-current output circuit connected to energize said motor field winding and having control winding means, said control Winding means comprising at least two control windings, circuit means connecting one control winding to said motor armature to be energized in dependence of motor armature current, an adjustable impedance connected to the other control winding, a second adjustable impedance connected to said impedance device, means mechanically connecting said first-mentioned and said second adjustable impedances to provide simultaneous adjustment, and means including reversing switch means connected to said first-named adjustable impedance to reversibly energize said first-named adjustable impedance.

13. In a direct-current motor control, a motor having an armature winding and a field winding, 21 main generator having an armature winding and field winding means including a differential field winding, circuit means connecting the generator armature winding to the motor armature winding, a pilot generator connected to and driven by saidmotor, an impedance device, circuit means connecting said differential field winding, said pilot generator and said impedance device across said generator armature winding, magnetic amplifier means having a direct-current output circuit connected to energize said motor field winding and having control winding means, said control winding means comprising at least two control windings, circuit means connecting one control winding to said motor armature to be energized in dependence of motor armature current, an adjustable impedance connected to the other control winding, a second adjustable impedance connected to said impedance device, means mechanically connecting said first-mentioned and said second adjustable impedances to provide simultaneous adjustment, means including reversing switch means connected to said first-named adjustable impedance to reversibly energize said first-named adjustable impedance, and an acceleration switch disposed to effect acceleration and deceleration of said motor and connected to said reversing switch means to control said reversing switch means.

References Cited in the file of this patent UNITED STATES PATENTS

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