US2474620A - Coiling machine controller - Google Patents

Description

June 28, 1949.

D. w. FATH COILING MACHINE CONTROLLER Filed April 12, 1947 Patented June 2 8, 1949 @FFECE 2&74320 CQFLENG MACHINE GONTROLLE'E Douglas W. Fath, Milwaukee, Wis., asaignor to Cutler-Hammer, Inc., Milwaukee, Wia, a corporation of Delaware Application April 12, i947, Serial No. more 7 Claims. (on. 242-75) The invention relates to motor control and while not limited thereto is particularly applicable to the control of motor driven wire drawing machines and the like. 1

Anobject of the invention is to provide a controller for motor driven wire drawing machines which accurately controls the preselected pull on the wire as it is drawn down to the desired size.

Another object is to provide a control which responds substantially instantaneously to variations in operating conditions so as to prevent undesired effects thereof on the wire.

Another object is to provide a constant pull on the finished wire to prevent breakage thereof.

Another object is to provide a controller which can be adjusted to afford selection of a desired speed of operation over a wide range of speed and output, and to maintain the selected operating speed and output substantially constant.

vAnother object is to provide a system which is readily adjustable for a wide range of Operating conditions.

Other objects and advantages will hereinafter appear.

In the accompanying drawing which is illustrative of an embodiment of the invention,

Fig. 1 is a diagrammatic illustration of a wire drawing installation, while Fig. 2 is a diagram of connections of the control system for the motor which draws the wire through the drawing dies.

Referring to Fig. 1, the wire whose diameter is to be reduced by drawing, is on a storage reel Hi, from which it is unwound by a capstan reel ll; over which the wire passes in-on'e or several turns and which it engages by friction. The cap- ,stan reel II is driven by a motor [2 which may be of any suitable type. The motor drives the capstan in the direction to unwind the wire from the reel l at the desired speed. The speed of the capstan motor may be varied to obtain a given linear speed of the wire as it enters the dies l3. The speed control of the motor l2 may be accomplished in various ways either automatically or manually. No means for controlling the motor I2 is shown as it forms no part of the present invention. After leaving the capstan the wire passes through a series of conventional wire drawing dies l3, only one of which is diagrammatically illustrated in the drawing. The wire diameter is reduced in its passage through the dies and the thus reduced wire is designated by the numeral Ill. The wire is drawn through the die by the pull exerted thereon by a second or drawing capstan M, which is also driven by the motor it. The connection between motor it an the capstans ii and M, respectively, is so ar ranged that the circumferential speed of capstan it is increased over that of capstan M in proportion to the elongation of the wire as it passes through the die iii. Instead of a single drawing capstan a plurality of such capstans, one for ach of a plurality of succeeding dies may be employed.

It is further possible to drive each capstan by an individual motor, their speeds being correlated to each other so as to correspond to the elongation and thus the successively increased linear speed of the wire. After the wire has passed the last drawing capstan it is led to a storage reel 15 on which it is wound. The storage reel i5 is positively driven being coupled to the armature l8 of a reel motor which has a shunt field winding ll supplied with direct current energy from a suitable source. The armature I6 is supplied with variable voltage direct current from the armature l8 of a generator which is driven at substantially constant speed by a suitable motor H9. The armature I8 is energized by a direct current fleld winding 20 supplied with current as will be explained hereafter.

It is necessary that the pull on the wire H) as it leaves the last drawing capstan be kept substantially constant. The pull is measured by leading the wire on its path between the capstan l4 and the roll l5 over a pulley 21. The pulley is mounted on one arm 22 of a double ended lever 23, which is pivoted about a stationary pivot 24. Theother arm 25 of the lever 23 has attached to its free end an iron core 26 which is movable axially with respect to a stationary magnetizing coil 21 to form therewith a regulating inductance whose impedance increases as the core 26 moves farther into the coil 21, upon the clockwise rotation of the lever 23, due to the pull exerted on the wire Ill by the reel IS. A spring 28 attached to the arm 22 tends to rotate the lever 23 counterclockwise in opposition to the clockwise rotation due to the pull by the reel l5. As the drawn wire accumulates on the reel IS the outer diameter of the spool of wire on the reel 15 increases. But as it is desired to maintain the drawing speed constant, the speed of rotation of the reel must be decreased. This necessitates a corresponding decrease of the speed of the armature l6 of the driving motor. As stated an increase of the spool diameter for any given speed of the motor increases the speed of and tension on the wire I0 such increased tension tending to rotate the lever 23 clockwise. The rotation and angular position of the lever 23 is employed to regulate the speed of the motor armature I6 so as to maintain a constant speed of the wire 16. As the lever rotates clockwise it moves the core 26 farther into the coil 21, thereby increasing the inductive reactance of the latter and this in turn reduces the speed of the armature I6 as will be explained hereafter.

Referring now to Fig. 2, the generator field is supplied with energizing current from the center tapped secondary winding 39 of a transformer 36, whose primary winding 36 is connected across the bus bars 3| and 32 of an alternating current source. The center tap of winding 90 is connected to one terminal of the field winding 20, whose other terminal is connected to each of the cathodes of a pair of gaseous rectifier tubes 33 and 34. The anode of tube 33 is connected to one and the anode of tube 34 is connected to the other end terminal of the transformer winding 96. Also connected across said end terminals and in series with each other are a resistor 35 and a capacitor 36, which form, with primary winding 31 of a transformer 31, connected between the center tap of winding 30 and the common terminal of resistor 35 and capacitor 36, a phase shifting network. The transformer 31 has a center tapped secondary winding 31", which winding is connected between the control electrodes of 'the'tubes 33 and 34.

The generator armature I6 is connected in a closed loop with the motor armature l6. Shunts 36 and 39 are interposed in series with each other in the loop between the positive terminals of the generator armature l8 and the motor armature I6. The positive terminal of the generator armature i6 is also connected to an intermediate terminal of a battery 40, the end terminals of which are connected through a voltage divider 4|, having a movable contact 4|. A similar battery 42 has an intermediate terminal connected to the positive terminal of the motor armature l 6, said battery being shunted by a voltage divider 43, having a movable contact 43a. The batteries 40 and 42 may be replaced by rectiflers which are supplied from an alternating current source and which in turn supply the required direct current voltage.

The system further includes a supply of direct current which impresses voltages of progressively increasing magnitude between a conductor 44 and conductors 45, 46 and 41, respectively. Preferably the conductor, is grounded, hence conductor 44 is at a negative potential, while conductor 46 is at a relatively low and conductor 41 at a higher positive potential.

The tubes 33 and 34 which supply the exciting current for the generator field winding 20 have their control electrode voltages controlled in response to the operating current of the generator armature l9 and motor armature l6 by four high vacuum tubes '48, 49, 50 and 51. The cathodes of tubes 46 and 49, are connected to the conductor 45, while the cathodes of tubes 56 and 5|, are connected to the conductor 46. Also connected to the conductor 45 is the common terminal of the shunts 36 and 39, while the negative terminal of the generator armature I 6 is connected to the conductor 45, through a voltage divider 52. The anode of tube 56 is connected to the center tap of winding 31 by a wire N, while the anode of tube 5| is connected to the cathodes of tubes 33 and 34. The control electrode of tube 50 is connected througnseries connected resistors 53 and 54 to conductor 41. The anode of tube 46 is connected to the common terminal of resistors 63 and 54. The control electrode of tube 5| is connected through series connected resistors 55 and 56 to conductor 41, while the anode of tube 49 is connected to the common terminal of resistors 55 and 56. The control electrode of tube 46 is connected to the contact 43' while the control electrode of tube 49 is connected to the contact 4|.

The system is made to respond to the tension of the wire III by the effect of said tension upon the coil 21. The coil 21 is connected in series with a. resistor 61 across a pair of taps intermediate of the center and the end taps respectively of transformer winding 36", while the common terminal of coil 21 and resistor 51 is connected through the primary winding 56' of a transformer 56 to the center tap of winding 39, thus forming a phase shift network. The voltage across resistor 61 is a function of the impedance of the coil 21 and thus of the variation in the tension of the wire. The secondary winding 53 of transformer 66 has a center tap which is connected to the conductor 44. Also connected to the conductor 44 are the cathodes of a pair of gaseous tubes 69 and 60, whose respective control electrodes are connected each to one of the end terminals of winding 56". The anodes of tubes 69 and 60 are connected each to one of the end termlnals of a center tapped secondary winding 6 l of a transformer 6|, the center tap of said winding being connected through a. voltage divider .62 to the cathodes of tubes 59 and 60. The primary winding 6i of transformer 6| is connected to the bus bars 3i and 32. The voltage divider 62 has a movable contact 62 which is connected through a resistor 66 to the control electrode of a high vacuum tube-64 whose cathode is connected to conductor 45, while its anode is connected through a resistor 65 to conductor 41 and through a resistor 66 to the anode of tube 56'. A condenser 61 is interposed between control electrode of tube 64 and the center tap of transformer winding 6i A high vacuum tube 68 has its cathode connected to the conductor 45 and its anode connected through a resistor 69 to the anode of tube 55 ,and through a resistor 10 to conductor 41. The control electrode of tube 68 is connected to conductor 44 through a resistor 1| and to the movable contact of potentiometer 52 through a condenser 12.

The system operates as follows: The operator starts the motor I! to unwind wire from the capstan l6 and threads the wire in the usual manner through the dies I3. He then leads the wire, after its diameter has been reduced by passage through the dies, over the capstan l4 and fastens it to the reel ii. The motor generator set has previously been started and the motor field I1 has been energized. Thereupon the generator field 20 is energized as will be explained more fully hereafter, causing the generator armature l8 to generate current which flows as aforedescribed through the motor armature l6 to rotate the same and thus rotate the reel IE to gather the wire III thereto by the rectifying tubes 33 and 34, whose Output current in turn is a well known nmction of the phase displacement and amplitude of their respective control electrode potentials. In operation the tension pulley 2| is held by the wire passing over it in a position which depends upon the tension of the wire and the opposing pull of the spring 28. As the pulley 2| moves up and down by variation of the wire tension it moves the core 25, thereby varying the inductance of the coil 21 in such a manner that the inductance increases with the tension of the wire Ill and vice versa. As the inductance of the coil 21 varies, it varies the time phase of the voltage impressed upon the primary winding 58 and thus also of the voltage which is impressed by the transformer winding 58 upon the control electrodes of the tubes 59 and 60. When the inductance of the coil 21 is a maximum, that is, when the tension of the wire In is a predetermined maximum, the control electrode voltages aforementioned are displaced sufliciently from the voltage impressed upon the corresponding main electrodes of the tubes 59 and G to render these tubes non-conducting during the respective en tire positive half cycle.

As the wire I0 accumulates on the reel l5, its diameter increases and if the reel speed remained constant, the tension on the wire would increase and this in turn would cause the lever 23 to rotate in a clockwise direction. This rotation increases the inductance of the coil 21, which in turn causes a phase shift of the voltage of the control electrodes of tubes 59 and 60 with respect to the voltage of their main electrodes, so as to render said tubes progressively less conducting. This in turn reduces the current in windin 20 and hence the generator voltage as a result of which the motor armature I6 is slowed down to maintain the wire speed and tension constant.

The output voltage of tubes 59 and 60 is impressed upon the resistor 62 and an adjustable fraction thereof, determined by the position of the movable contact of 62 is impressed on condenser 61 to charge the same. The voltage of the condenser thus varies with variations of the output voltage of tubes 59 and 60, the rate of change of the condenser voltage upon sudden variations of the tube output voltage being dependent upon the value of resistor 63. The voltage of the condenser 51 plus the negative potential of the conductor 44 are impressed between the control electrode and the cathode of tube 64. This biasing voltage increases in a negative sense as the current of the tubes 59 and 60 increases. Thus an increase in the tension of the wire produces a negative change of the bias of the tube 64 with a corresponding reduction of its current and of the voltage drop through the resistor 65. This makes the anode of tube 64 increasingly positive with respect to ground potential. The control electrode of tube 68 is normally at a given negative potential with respect to its cathode due to its connection to conductor 44 through the resistor II. This negative potential of the control electrode however is not sufficient to cut off current conduction through the tube 68. The current through tube $8 produces a voltage drop across resistor 10 which makes the anode of the tube 68 positive with respect to its cathode which is at ground potential.

Under normal running conditions the tubes 50 and are non-conducting as their respective control electrodes are biased negatively beyond the cutoif potential as will be pointed out hereafter. Therefore there is no voltage drop through resistors 66 and 69, respectively, so that anode of tube 50 is at the potential of the anode of tube 64 and the anode of tube 5| is at the potential of the anode of tube 68. Thus when the output of tubes 59 and I0 is zero, the bus bar N is negative with respect to the bus bar L. As the output currents of tubes 59 and 60 increase due to decrease of tension on the wire ID, the potential of bus bar N changes in a positive sense with respect to the potential of bus bar L,

The tubes 53 and 34 are controlled by control electrode voltages one component of which has a fixed-phase displacement relative to the corresponding plate voltage. As aforedescribed this component is derived from the phase shifting network including winding 31, resistor 35, and capacitor 35. Superimposed on this alternating voltage is a variable direct current bias supplied by the bus bars L and N which varies the moment of ignition of said tubes 33 and 34. As the potential of bus bar N changes in a positive sense with respect to the bus bar L, the output current of the tubes 33 and 34 is increased by advancement of their critical control electrode potential, and the increased output current passes through the generator field winding 20 of the reel generator, thus increasing the voltage of the generator armature 18, thereby increasing the current supply to the motor armature i6, and the torque of said motor in accordance with the load thereof. A decrease of the pull on the wire H1 decreases the inductance of the coil '21 which advances the moment of ignition of the tubes 59 and 50. This in turn varies the bias applied to the control electrode of tube 64, to increase the effective current of said tube with the final result that the potential applied to the anode of tube 50 and bus bar N changes in a positive sense and an increased positive potential is applied to the grids of the tubes 33 and 34. This increases the current through said tubes, resulting in an increase of the excitation of the generator field winding 20, and thereby increasing the reel motors speed.

The bias battery 42 supplies a bias voltage for the control electrode of tube 48. This bias voltage is adjusted through adjustment of the potentiometer resistor 43. The movable contact 43 is normally so adjusted that the aforementioned bias voltage is positive. This permits the passage of a current through the tube 48, which current produces a voltage drop through the resistor 54. The fiow of current through the resistor 54 depresses the voltage of the anode of tube 48 with respect to the voltage of the conductor 4! to the extent that the potential of the control electrode of tube 50 becomes sufiiciently negative with respect to its cathode so as to render the tube 50 nonconducting. As the current in the loop including the motor armature I B and generator armature [8 increases, the voltage drop across the shunts 38 and 39 increases in a manner such that the terminal of the shunt 39 nearest the battery 42 becomes increasingly negative. This negative voltage is superimposed upon the aforementioned positive bias voltage derived from battery 42, with the result that the potential of the control electrode of tube 48 and the plate current of said tube are reduced, so that the voltage drop across the resistor 54 also decreases, and the potential of the control electrode of tube 50 increases and ultimately allowing tube 50 to pass current. This current produces a voltage drop across resistor 66 which makes the anode of tube 50 and the bus bar N more negative with respect to the bus bar L. This results in turn in a retardation of the moment of ignition of the tubes 33 and 34, so that the latter will conduct less current, thereby reducing the energization of generator field 20 and the supply of current by the generator armature I8 to the motor armature Hi. If the value of the bias voltage impressed by the potentiometer resistor 43 upon the control electrode of tube 48 is varied in a negative sense, the effective positive bias impressed upon tube 48 decreases. This will permit adjustment so that a lower reel motor armature current produces a sufilcient voltage drop across the shunt 39 to counteract said lower battery bias for obtaining the critical negative voltage of the control electrode of tube 48 at which the armature current control'becomes effective.

If the load of the armature l6 should increase, that is, if the tension of the wire ill should increase, the inductance of the coil 27 increases, producing an effect on the tubes 59 and 60 opposite to that heretofore explained.

Upon rapid decrease of the motor load, the generator tends to function as a motor as long as the motor armature voltage is higher than the generator armature voltage. In that case, the voltage drop through the shunt 38 and the voltage derived from the potentiometer 4| will affect the tube 49 to function in the manner heretofore described in connection with tube 48, with the result that the supplemental bias voltage impressed on the bus bars L--N is now the opposite of that produced during load increases so as to retard ignition of tubes 33 and 34, and reduce the strength of the generator field current, whereupon the motor supplies energy to the generator and its speed is accordingly kept from rising excessively.

As the effects aforementioned take place at a very rapid rate, cumulative hunting might result. In order to prevent such hunting the capacitors 5'1 and 12 are provided.

The capacitor 6'! together with the associated resistors 63 and 62 comprises a differentiating circuit which supplies a voltage to the control electrode of tube 64 as a function of the rate of change of, the control voltage supplied by the tubes 59 and 60. Upon changes of the wire tension the voltage change in the coil 21 and resistor 56 which as explained, ultimately causes a change in the current through the exciting winding 20, is initially rapid and gradually decreases. The initial rate of change is a function of the speed of movement of the lever 23, while the decrease of the rate of change of the control voltage from its initial value is determined by the value of the capacitor 61 and the value of resistor 63.

In order to prevent the aforementioned differentiating circuit from causing the regulation to overshoot whereby the system temporarily would acquire a speed in excess of that actually called for by the wire tension, a component of the voltage of the generator armature I8 is impressed upon the control system by means of the potentiometer 52 and the capacitor 72. Upon rapid increase of the generator voltage the capacitor 72 will cause the control electrode of tube 58 to become more negative, thereby decreasing the plate current of said tube, and reducing the voltage drop across the resistor 10, which in turn raises the potential of the bus bar L with respect to that of the bus bar N. This in turn varies the bias voltage applied to the tubes 33 and 34 in a negative sense, resulting in a reduction of their output current and of the excitation of the generator field 20, and therefore also of the output voltage of the generator armature l8.

From the foregoing it will be apparent that the accelerating current which the generator delivers to the motor may be adjusted by varying the sup,-

plemental biasing voltage impressed by the potentiometer resistor 43 on the control electrode or tube 48. Similarly the decelerating current which flows from the motor to the generator may be adjusted by adjustment of the poten tiometer resistor 4 I. Furthermore, the maximum rate of acceleration of the motor armature may be regulated by adjustment of the potentiometer 02, while the maximum rate of change of the braking current, that is, the decelerating current of the motor is adjustable by adjustment of the potentiometer 52.

It will be apparent to those skilled in the art that the system described is capable of modifications and that it may be provided with additional safeguards for controlling the equipment under certain contingencies, without departing from the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. For use with a wire drawing machine having a reel for receiving and storing the drawn wire, the combination with a source of electric energy, of a driving motor for the reel connected to said source, electronic regulatin means including an impedance device responsive to the tension exerted upon the wire by the reel for regulating the energy flow between said source and motor, said regulating means tending to vary said flow in excess of the variation required by said tension responsive means, and means responsive to said flow to check the effect of said regulating means substantially coincident with attainment of the required tension.

2. For use with a wire drawing machine having a reel for receiving and storing the drawn wire, a motor in driving connection with the reel and a generator for supplying variable energy to said motor, the combination with electronic regulating means, includin an impedance device responsive to the tension exerted upon the wire by the reel, for regulating the energy flow between said generator and said motor, said regulating means tending to vary said flow in excess of the variation required by said tension responsive means, of means responsive to said energy flow to check the effect of said regulating means substantially coincident with attainment of the required tension.

3. For use with a wire drawing machine having a reel for receiving and storing the drawn wire, the combination with a direct current motor for drivin the reel, of a direct current generator, said motor and said generator having their armatures connected in series with each other, electronic regulatin means, including an impedance device responsive to the tension exerted upon the wire, connected in circuit with a winding of said generator for varying the current flowing in said generator winding in response to variations of the tension of the wire, said regulating means tending to vary said current flow in excess of the variations required by said tension responsive means, and means responsive to the flow of current in said armatures to check the effect of said regulating means substantially coincident with attainment of the required tension.

4. For use with a wire drawing machine having a reel for receiving and storin the drawn wire, the combination with a direct current motor for driving the reel, of a direct current generator, said motor and said generator having their armatures connected in'series with each other, a source of exciting current, electronic regulating means, including an impedance device responsive to the tension exerted upon the wire, connected in circuit with a field winding of said generator and said source for varying the current in said field winding in response to variations of the tension of the wire, said regulating means tending to vary said field winding current in excess of the variations required by said tension responsive means, and means responsive to the flow of current in said armatures to check the effect of said regulating means substantially coincident with attainment of the required tension.

5. For use with a wire drawing machine having a reel for receiving and storing the drawn wire, the combination with a direct current motor for drivin the reel, of a direct current generator,

said motor and said generator having their armatures connected in series with each other, an alternating current source, electronic rectifying and regulating means, including an impedance device responsive to the tension exerted upon the wire, connected in circuit with a field winding of said generator and said source for varying the current in said field winding in response to variations of the tension of the wire, said regulating means tending to vary said field winding current in excess of the variations required by said tension responsive means, and means responsive to the flow of current in said arinatures to check the efiect of said regulating means substantially coincident with attainment of the required tension.

6. For use with a wire drawing machine having a reel for receiving and storing the drawn wire, the combination with a direct current motor for driving the reel, of a direct current generator, said motor and said generator having their armatures connected in series with each other, an alternating current source, a first electronic valve means connected to said alternating current source and in circuit with a field winding of said generator to supply a rectified alternating current thereto, a phase shifting network connected in circuit with said alternating current source and to said first electronic valve means for controlling the impedance of the latter, a second electronic valve means connected to said alternating current source, an impedance variable in response to the tension exerted upon the wire and connected to said second electronic valve means to control the output voltage thereof, a third electronic valve means connected to said phase shifting network and arranged to control the latter in accordance with variations of the current flowing between said armatures, and a fourth electronic valve means including energy storing means and arranged to respond to said second electronic valve means and to the rate of change of the voltages of said armatures and also to the operation of said third electronic valve means for modifying the efiect of the latter in accordance with the variations of said impedance.

'7. For use with a wire drawing machine havin a reel for receiving and storing the drawn wire, the combination with a direct current motor for driving'the reel, of a direct current generator, said motor and said generator having their armatures connected in series with each other, an alternating current source, a first electronic valve means connected to said alternating current source and in circuit with the field windin of said generator 'to'supply a rectified alternating current thereto, a phase shiftin network connected in circuit with said alternating current source and to said first electronic valve means for controlling the impedance of the latter, a second electronic valve means connected to said alternating current source, an impedance variable in response to the tension exerted upon the wire and connected to said second electronic valve means to control the output voltage thereof, a third electronic valve means connected to said phase shifting network and arranged to control the latter in accordance with variations of the magnitude and direction of the current flowing between said armatures, and a fourth electronic valve means including energy storing means and arranged to respond to said second electrc; ic valve means and to the rate of change of the voltages of said armatures and also to the operation or" said third electronic valve means for moditying the effect of the latter in accordance with the variations of said impedance.

DOUGLAS W. FATE.

No references cited.

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