US 2283036 A
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Description (OCR text may contain errors)
May '12 1942.
D. l. BOHN REEL CONTROL Filed April 15, 1939 mvsm'ox DONALD I. Bot-1N.
Patented May 12, 1942 UNITED STATESPATENT OFFICE mesne assignments, facturing Company, ration of Delaware to Allis-Chalmers Manu- Milwaukee, Wis., a corpo- Application April 15, 1939, Serial No. 268,106
This invention relates to mechanisms for tension unwinding and rewinding of strip material and the like, which may be used in conjunction with mechanisms for rolling, processing, or otherwise feeding strip material and the like. It
relates particularly to electrical control systems for reel mechanisms capable of maintaining constant tension on material delivered to or from a rolling'mill, which employ photo-electric torquecontrolling means responsive to change in radius of material on a drum or reel. While the invention is particularly adapted to controlling strip material reels it will be apparent that wire spools and the like could be controlled by the apparatus disclosed herein, but reference is made particularly to strip reel mechanisms.
It is recognized in rolling practice that the speed of rolling strip material may be greatly increased, and the quality of the product may be materially improved, when a predetermined tension is exerted upon the strip material before, after, or both before and after it is passed through a rolling mill. Coil unwind and rewind mechanisms may be conveniently used for applying tension to the material by applying substantial resistive forces or motive forces, respectively, thereto. In other words, the back torque on an unwinding coil or reel may be controlled to exert and maintain tension on the material before it enters a mill; or drive torque on a rewinding coil or reel may be controlled to exert and maintain tension on the strip material after it passes from a mill. Since the increment of torque necessary to overcome frictional and bending losses, to effect uncoiling or recoiling of strip material, is small compared to the torque required to exert'a substantial tension in the material, the forces necessary to exert such increment of torque may be disregarded for purposes of this disclosure, though they may be compensated for in the apparatus disclosed.
For further reasons known in the art, it is desirable to apply the tension at a constant predetermined value and to maintain the tension constant at all speeds independently of the driving means for the mill or other apparatus through which the strip material is rolled, processed, or otherwise fed. In order to exert constant tension on the material delivered to or from a rolling mill, the torque developed by the unwind resisting apparatus, or by the rewind driving apparatus, must be progressively changed to compensate for the change in radius of the coil of material. The decreasing radius of an unwinding coil may be referred to as run-down, and
the increasing radius of a rewinding coil may be, and commonly is, referred to as build-up.
Early recognition of the problem of compensating for build-up on a rewind reel is found in prior art disclosing mechanical means employing clutches, slip-gears, brakes, and the like, for adjusting rewind drive torque. Also, certain electrically controlled systems have been developed to supplant the mechanical devices. The electrically controlled systems have usually operated on a common fundamental principle, in
that the rewind motor has been coordinated with the mill motor. The several types of prior, rewind torque-controlling devices are referred to in my earlier Patent No. 2,043,208, patented June 2, 1936, and entitled Motor control system for coiling mechanisms," which discloses a- .urther improvement in electrical control devices obviating the necessity of employing auxiliary equipment to supplement the power developed by the mill motor for driving a coiler motor.
The present invention obviates the low degree of accuracy, and sluggish operation resulting from wear, in mechanical control means. The present invention further is an improvement over former electrical control means, and is an improvement over my prior patent, firstly, in being operable independently of the mill drive and entirely independently of the speed of the material, and secondly, in being operable in direct response to change in coil radius.-
This invention is particularly concerned with a photo-electric means, sensitive to change in radius of the material on a reel, for operating a means for varying back torque or drive torque on the reel. The device of the present invention has at least two particular advantages over mechanical devices, such as have been used in the past, for responding to change in radius of the material on the reel: First, no roller or other mechanical element need touch the strip material. It follows, therefore, that marking or scratching of the strip material being processed, especially noticeable on light metals such as aluminum, is entirely avoided. Second, the photo-electric device and associated means may be located out of the way of the operator, as by placing it beneath the reel or coil, permitting the torque-controlling system operatedbyjhe photo-electric device to be located in any convenient place removed from the reel or coil.
The present invention is, then, directed toward overcoming the undesirable factors inherent in formerly known unwind or rewind mechanisms. It has for an object the provision of photo-electric means for controlling back torque or drive torque of such mechanisms, whereby any predetermined constant tension may be maintained on the material being processed. Another object is to maintain constant tension on the material being processed, regardless of speed or change in radius of the material on the reel.
Further objects of this invention are to make it possible to predetermine the tension to be applied to the material, to employ otherwise constant torque resisting means or driving means for the reel, to eifect variation in the torque in proportion to change in coil radius, to register or indicate changes in coil radius without marring the material, and to effect translation of indications of change in coil radius into impulses for varying back or drive torque.
These and various other objects, as well as other novel features and advantages of the invention, will become apparent in considering the following detailed description of preferred embodiments of the invention, set forth in conjunction with the accompanying drawing which represents, diagrammatically, an arrangement of the improved constant tension, photo-electric control system for a strip material reel mechanism.
Since a description of this invention as applied to control of a strip material rewind drive is exemplary of the novel features, reference will first be made to such an apparatus. As will appear throughout this specification, however, a rewind drive control apparatus may be adapted to function as an unwind resistive control apparatus without any fundamental changes in the system; and, as will be evident to one skilled in the art, the principle of operation of the rewind mechanism first disclosed will remain substantially the same, when converted to or used as an unwind mechanism. When used as an unwind control mechanism, the power fiow, in what is presently described in the immediately following embodiment of the invention as a reel driving motor, a generator, and a prime mover, would be reversed. The motor and the prime mover would act as, or be replaced by, generators; and the generator would act as, or be replaced by, a motor.
The drawing may be considered illustrative of the invention as applied to the control of a rewind reel or coiler mechanism such as is employed in conjunction with a rolling mill. The apparatus shown comprises a rolling mill or other suitable feeding device employing a pair of rolls I and II, which may or may not be driven as desired. The strip material 12, or other stock to be coiled after passing through rolls Ill and I i, is shown engaged on the discharge side of the rolling mill upon a coiler reel l3 of any suitable construction. An initial turn or coil H of the strip material I 2 is shown wound on coiler l3. Coiler I! has mechanically coupled thereto a suitable driving motor l5, preferably a fully compensated, shunt excited, direct current motor.
The preferred characteristics of the coiler drive motor I! are set forth presently for clarity in describing the invention. The shunt excited D. C. motor I5 is capable of exerting a torque proportional to its armature current and to its ellective field flux. In the embodiment -of the invention disclosed, the armature current is riaintained at a, constant value by a current regulator system in a loop circuit hereinafter described. Since the armature current may be maintained constant, the torque of the coiler drive motor I 5 may be made dependent upon its field strength. Control of field strength may be conveniently adjusted by means of a multiple position rheostat inserted in the circuit of the coiler motor field, the operation of which by a photo-electric device and associated means is hereinafter disclosed in this specification.
The tension on the material I! is directly pro portional to the torque of the drive motor l5 and inversely proportional to the radius of the coil I4. Therefore, with a constant armature current, tension becomes a function of field strength and coil radius; and the former may be progressively adjusted to compensate for progressive change in the latter.
Control of coiler drive torque by maintaining constant armature current, and by varying the field strength, may be independent of the mill speed or of the strip material speed; and the tension on the material may be maintained at a constant value regardless of its speed.
Coiler drive motor I5 is excited by a field winding l6. Current is supplied to field winding I 6 through conductors l1 and I8; and a field rheo- P stat I9 is located in circuit with conductor ll for varying the current supplied to field winding l6, thus providing a means for controlling the excitation of coiler motor l5. Conductors l1 and I 8 connect with power mains L1 and L2, respectively, which may be, for example, 230 volt, direct current constant potential mains. A rotatable arm 20 on rheostat i8 is adapted to be moved around the contact portions of rheostat I! for changing the resistance in circuit with field IS. The rheostat I9 is designed so that equal increments of rotational movements of arm 20 inserts in, or withdraws from, circuit with field I6 such increments of resistance as will cause equal changes in the torque developed by motor l5. In other words, rheostat I9 is pref erably constructed in accordance with the torque characteristics of motor l5 so as to give a straigt-line relation between angular movement of arm 20 and change in torque of motor I5. The operation of rheostat arm 20 on rheostat I! by a photo-electric device and associated electri-' cal means is described following a disclosure of a means for supplying constant armature current to motor I 5.
Armature current may be supplied to coiler motor l5 by any convenient system of adjustable constant current supply. A typical constant current supply system is illustrated diagrammatically in the drawing and comprises a generator 2! in a loop circuit with the motor I 5, the generator 2| being driven through a suitable mechanical coupling with a prime mover 22. Prime mover 12 may be any convenient approximately constant speed type of motor, and is dissociated from the mill drive motor; it is shown in the drawing as a three-phase alternating current induction motor operated ofi three-phasev power mains L3, L4, and L5 of suitable potential. Conductors 28 and 24 connect the armatures of generator 2| and motor l5, respectively, in a locp circuit. Inserted in circuit with conductor 23 is an ammeter 25, which may be employed for checking the loop circuit current value, whereby the operator may determine whether or not the current is remaining constant and whether it is at a proper value for any predetermined constant tension to be applied to the strip material, as a check upon a current regulator rheostat setting to be hereinafter described. Ammeter 25 may be calibrated to read in units of tension aasaoac 3 directly, if desired. In series with conductor 23, there is a shunt 28, across which a coil 33 is connected, as will be described, for a current regulator identified generally by the reference numeral 21.
The excitation of generator 2| is produced by a field winding 28 excited and controlled in conjunction with the current regulator 21. A resister 29 is adapted to be connected across the direct current mains Li and La through a doublepole, double-throw switch 30, the central terminals of which connect to mains L1 and L2 through conductors I32 and 32, respectively. One connection for field 28 is normally made to main L: by means of a conductor 9|, through conductor 32 connected to main L2. The second connection for field 28 is normally by means of a conductor |3| connecting to a potentiometer tap 33 on resistor 29 (through all, part, or none of the resistance of which the exciting current for field 28 must pass), knife switch 38, and.
conductor |32. Switch 30 is shown closed in its normal position for operation of the mechanism as a rewind. The second position of knife switch 30, shown dotted, is adapted to reverse the connection to resistor 29 without reversing the connections to field 28, for operation of the mechanism as an unwind. The latter change becomes necessary to accommodate the proper action of regulator 21 to the change in electrical power flow when the mechanism is used as an unwind. Current regulator 21 operates to control the position of potentiometer tap 33 along the resistor 29, the above-described field connection being referred to as a potentiometer connection.
Current regulator 21 comprises the operating coil 33 connecting across shunt 26 through lead wires 35 and 36. Inserted in circuit with lead wire 38 to coil 33 is an adjustable rheostat 31 having a control arm 38, by means of which the resistance in circuit with coil 33 may be controlled. Coil 33 is operable to move a magnetic plunger 39 mechanically connected to the potentiometer tap 33 on resistor 29. Plunger 39 may be spring resisted or'merely adapted to resist the force of coil 33 by its own weight, such device being known in the art and, therefore, not necessitating further description here. Rheostat control arm 39 may be set at any predetermined p'osition, thereby controlling the relative strength of coil 33 and adapting it to adjust the position of the tap 33 on resistor 29 in response to any tendency toward change in loop circuit current so that the strength of field 28 may be adjusted to maintain constant current in the loop circuit comprising generator 2|, motor l and conductors 23 and 23. Rheostat 31 may be calibrated to read in units of tension rather than units of pre-set coil current strength or-loop circuit current strength. Thus the operator may set the arm 38 of rheostat 31 for any given predetermined constant tension on material l2, which setting may be checked during operation of the apparatus by reference to the aforementioned ammeter 25, which then serves to indicate whether the apparatus is functioning properly.
To summarize, the current regulator 21 is adapted to modify the strength of field 28 to maintain a constant current output from generator 2|; and the rheostat 31 is adapted to control the magnitude of the current in the loop circuit for any given setting. In further illustration, it may be said that since regulator 21 is always attempting to adjust field 28 of generator 2| for a constant armature current, it will do this regardless of the value of field current and regardless of the value of generator voltage required to produce the constant current. This means that, for a given setting of arm 38 of adjustable rheostat 31, the armature current will be maintained at a constant value through motor I! regardless of the voltage required and regardless of the mill speed or coiler speed, down to and including zero.
The foregoing apparatus for supplying any predetermined constant current to motor l5 has been set forth only as an example of a convenient apparatus for providing such constant current. A similar apparatus, of which the above-described apparatus is a modification, will be found fully set forth in my prior Patent No. 2,043,208.
With constant excitation of field IS, the foregoing system may be employed to produce any desired predetermined constant torque in the coiler drive motor l5. As aforementioned, the torque of the coiler motor I5 must be varied to compensate for change in radius of the coil l3 in order to maintain the predetermined constant tension on the strip material |2.- .The effect of change in radius or build-up of strip material forming coil 3 may be offset by increasing the strength of the field iii of motor IS. The aforementioned field rheostat l9 has been provided for this purpose. A rheostat driving motor 30 is suitably mechanically coupled with rheostat arm 20, and is adapted to move the arm 20 to vary the resistance in circuit with field I6. A photoelectric device and associated means, which are novel features of this invention, are employed to automatically change the torque of motor l5 by operating the rheostat driving motor 30. Movement of rheostat arm .20 may be effected in such a manner as to accurately effect the change in torque required to maintain constant tension in the strip material, that is, according to changing build-up radius of the strip material on coiler I3. It will now be apparent that if rheostat arm 2|! is properly adjusted as the build-up radius of coil H on coiler l3 increases, the torque of motor IE will be accordingly increased to compensate for the increase in build-up.
The photo-electric build-up compensating system comprises a light source generally identified by reference numeral 3|, a photo-electric cell 32, and an electrical system associated therewith. Light source 3| may be comprised of any convenient form of lamp or bulb 33, and is preferably used in conjunction with a parabolic reflector 33 adapted to direct substantially parallel rays of light across some lateral portion of the build-up path of the strip material forming coil l3. Light source 3| may be conveniently and securely attached to any suitable foundation, as by means of a bracket 35. In the form of the invention shown in the drawing, a beam of substantially parallel light rays 36 is directed past the underside of coiler l3 so that one edge of the beam would intercept the coiler or reel l3 if there were no material thereon, the other edge of the beam being sufficiently spread downwardly as to pass through the space to be occupied by a fully wound coil of material on coiler l3. The
but slightly diverging rays of light may be used to accomplish the same purpose and will magnify the change in radius of the coil I4. The beam of light rays 48 is directed toward the photo-electric cell 42, also located below the pass line of the strip material on the opposite side of the coiler II from the light source 4I. Placing light source 4I, photo-electric cell 42, and the associated apparatus below the pass line of the coiler and the mill permits greater freedom of movement on the part of the operator, without interfering with the operation of the apparatus; but it is obvious that the beam could be disposed above the coiler or could be directed parallel to the axis of the coiler or at an angle thereto, as may be found desirable.
In more particular description, the photo-electric cell 42, which may be provided with a suitable shield or other optical device 41 for receiving a small increment of the rays of light 40 and directing them upon the light-responsive portion of the photo-electric cell 42, is mounted upon'a vertically movable rack 48. Thus the photoelectric cell is movable across the rays of light 46 in a direction perpendicular thereto and perpendicular to the axis of coiler I3. Other suitable directions of movement for photo-electric cell 42 could be chosen if desired. Rack 48 is shown diagrammatically as slidable in vertical guides 49 and 50, and is movable in these guides to traverse photo-electric cell 42 over the full span of the beam of light rays 46. A pinion engages the rack 48 and is adapted to move and locate the rack 48 to bring the photo-electric cell 42 into or out of the unintercepted rays of light beam 46. Pinion II is driven by a self-synchronous, tie motor 52 operable as a receiver of electrical impulses from a corresponding selfsynchronous, tie generator ll, operable as a transmitter of electrical impulses. The self-synchronous, tie generator 53 is. mechanically coupled to the aforementionedrheostat drive motor 40. The self-synchronous, tie motor 52 and tie generator 53 are devices known in the art,
which are adapted to Operate in exact relation with each other, being full electrical equivalents for a mechanical coupling therebetween. The self-synchronous. tie motor and tie generator are used in this embodiment of the invention to make it possible to space, or separate, the apparatus for driving rheostat arm 2| away from the photo-electric apparatus, which must be located adjacent the coiler I2. Rotors 54 and 55 of tie motor 82 and tie generator ll, respectively, are supplied with alternating current by means of conductors 58 and 51 connecting both rotors l4 and 55 to power mains La and In, which may be 110 volt, 60 cycle, alternating current mains, for example. Leadwii'es'il, 59, and 0 connect the stators of tie motor and tie generator 53 for carrying the control currents transmitted by tie generator I3 to the tie motor 52. It is to be noted at this point that the movement of photoelectric cell 42 across the beam of light 46 is directly coordinated with the movement of rheostat arm 24 by the aforementioned system including the tie generator and tie motor.
Photo-electric cell 42 is connected to, and associated with a relay box I by means of lead wires 42 and 48, photo-electric cell 42 and relay box I comprising one of several standard forms of photo-electric relays. Relay box I is energized by power from mains Ls and L1, supplied through conductors 84 and ill. The assembly of photo-electric cell 42 and relay box OI may be a standard photo-electric unit as aforesaid and, therefore, its detailed wiring has not been shown in the drawing.
The driving means for rheostat arm 20 and rack 48 is controlled by the photo-electric unit through relay box II. The drive motor 40, coupled to the rheostat arm 20, is preferably a splitseries-field electric motor, and is also coupled to the self -synchronous tie generator 52, as aforesaid. Split-fleld drive motor 40 has two series fields O6 and 61, and is adapted to operate in opposite directions as one or the other field, it or I1, is excited. Drive motor 40 is connected through conductor 68 and resistor 69, if desired for speed control, to the current main L1; it is also connected to the current main 1a through a conductor 10.
In circuit with conductor 10, the second lead to motor 40, is a single-pole, double-throw contactor switch having a contact member H, operable to send current either through a lead wire 12, a hand controlled switch I14, and field 81, or through a lead wire 13, a hand controlled switch 14, and field 86. Contact member 1I may be gravity operated or spring operated to normally connect to lead wire 12, being operable by a coil operated plunger 15 to make contact with lead wire 13. Coil operated plunger 15 is operable to move contact member H from its normal contact with lead wire 12, by means of a coil 18 which may be energized from relay box 6| by current through lead wires 11 and 1!, to make contact with lead wire 13, in response to impulses from relay box 8| initiated by light impinging upon photo-electric cell 42. Photo-electric cell 42 and relay box 6| are so connected to the coil 1| for contact member 1I that, whenever the light source 4| illuminates cell 42, contact member H is energized to make contact with lead wire 13. At this point, if switch 14 is closed, motor 40 will be caused to rotate in a direction toward increasing the resistance of rheostat IS. Cell 42 and relay box SI are further related to coil 16 so that, whenever light directed toward cell 42 is intercepted by coil I4 and cell 42 is not illuminated, contact member H is pulled by aspring or by gravity to make normal contact with lead wire 12. At this point, if switch I14 is closed, motor 40 will be caused to rotate in a direction toward decreasing the resistance of rheostat I9. Thus motor 40 will be energized to run in either one direction or the other, there being no "0!!" position of contact member 1|. The foregoing statement has been made with the assumption that switches 14 and I14 have been closed. The effect of these latter switches on the operation of the apparatus will be set forth hereinafter.
The torque-controlling apparatus having been described, its operation may now be set forth. For simplicity of description, it is first assumed that'coil I4 is in an initial position as illustrated on the drawing, mechanism and controls for threading strip material I2 upon the coiler I! being omitted since they do not form a necessary part of this description. It is further assumed that rolls I I and II and coiler I3 are at rest and that the photoelectric cell 42 is in a dark position, that is, where it is not receiving light from light source 4|; that contact member H is in its normal position in contact with lead ,wire 12; and that switch I14 is closed. Under these conditions current will flow to the drive motor 40 through series field 61, causing drive motor 40 to turn rheostat arm 20 on rheostat IS in a direction to decrease the resistance in circuit with the field 16 of the coiler drive motor l5, thereby increasing the torque developed by coiler motor IS. The rotor 55 of the self-synchronous, tie generator 53 is simultaneously turned by the drive motor 40 and transmits electrical impulses to the self-synchronous, tie motor 52. The tie motor 52 simultaneously rotates pinion 5| in a direction to move rack 48 downwardly. This action moves the photo-electric cell 42 downwardly into a light position, that is, into unintercepted rays of the light beam 46. The optical device 41 associated with the photoelectric cell 42 will be moved into the first rays of light passing beyond the coiler l3 and under the outer layer of material on coil l4. At the moment light strikes the photo-electric cell 42, the relay box 6| receives impulses from the photo-responsive element in the photo-electric cell 42. The relay box 6| energizes coil 18, causing contact member 1| to open the circuit going to series field 61 of motor 40 through lead wire 12 and to make contact with the lead wire 13, closing part of the circuit to field 66 and drive mo- ,tor 40. At this point, if the switch 14 in lead wire 13 is open, in the position shown on the drawing, no further operation of equipment will take place until there is some change in the radius of the coil l4 which, for present purposes, has been assumed to be stationary.
The operation 0 e apparatus with switch 14 open, however, is not the only method of using the equipment illustrated. A second method of using the apparatus results if switch 14 has been previously closed before the movement of contact member 1 I, to make contact with lead wire 13. Under this condition, the drive motor 40 will be immediately reversed to rotate in opposite direction, being energized by field 66. The rotation of drive motor 40 in a reverse direction simultaneously decreases the torque of the coiler drive motor 15 and moves the photo-electric cell 42 back out of the light beam 46 into a dark position, whereupon, substantially at the movement of the cell into the dark position, the coil 16 is de-energized, no current flowing from the relay box SI, and contact member 1| returns to its normal position in contact with lead wire 12. Upon the closing of contact member 1| upon lead wire 12, the above-described oscillating cycle will be repeated and will continue.
ferred to as a stop-and-go or continual movement. Simultaneous with the movement of the photo-electric cell 42 will be the movement of rhecstat arm 20 to decrease the resistance afforded by rhecstat It in circuit with the field lb of the coiler drive motor l5.
If the switch 14 has also been closed and the coiler I3 is in operation, the torque-controlling apparatus will function in a manner similar to that secondly described above, except that the photo-electric cell 42 will have a hunting motion. In other words, the photo-electric cell will be continuously moved into and out of the edge of the beam of light 46 passing beyond the coiler l3 in an oscillating cycle and will follow the built-up, and the interception of light thereby,
with a back and forth motion of small magni-' tude. Rheostat arm 20 will be moved in accordance with the motion of photo-electric cell 42, but a small amount of backlash may be left in the couplings to rhecstat arm 20, whereby the slight backward movement of photo-electric cell 42 may not necessarily be transmitted to rheostat arm 20. Further, in this manner of operating the above-described equipment, when the coil I4 is removed from coiler l3, the photo-electric cell 42 will automatically be traversed back to its starting position and the' rhecstat arm 2|! will be likewise turned back to its initial position. However, if the switch 14 be left open,-
as in the first described operation wherein the stop-and-go action of the photo-electric cell is used, the switch 14 or some other control must be closed to return the apparatus to initial position, after a completed coil l4 has been removed from the coiler l3.
From the foregoing description of a preferred form of theapparatus and two methods of its operation, it may be said that, by properly designing the rheostat l9 and the rhecstat 31, a constant current through the armature of coiler motor l5, and a-constant tension applied by the coiler motor l5 may be maintained. These conditions will result in a constant tension on the material being processed regardless of the mill speed, down to and including a full stop. The behavior of rhecstat I8 is substantially the same as though the rhecstat arm 20 were mechanically operated by a roller on a fulcrumed arm rid- Up to this point the apparatus has been assumed to be at rest. If coiler I3 is now assumed to be in motion with the coiler motor [5 developing a preset torque determined by a particular setting of arm 38 on rhecstat 31, the radius of build-up of strip material on coiler I3 will be progressively and continuously increasing, though it will be increasing at a decreasing rate. The build-up of strip material on coiler l3 will gradually cut oil;' more and more rays of light in the beam 46, which will require progressive movement of rack 48 and rhecstat arm 20 as will now be described.
With the switch 14 open, switch I14 closed, and coiler l3 in operation, the torque-controlling apparatus will function as first described above,
except that the photo-electric cell will be moved until it receives light and then will remain at rest until build-up cuts off light. The cycle will begin again and continue when light is cut off from optical device 41, photo-electric cell 42 being moved in successive, progressive, intermittent movement following the build-up of strip material on coiler I3. This movement may be reing in contact with the coil [4, the arm being adapted to actuate the rhecstat arm 20 in response to build-up of strip material on the coiler. In other words, the rhecstat arm 20 will have a definite position for every outside diameter of the coil l4.
Before describing the aforementioned preferred embodiment of the invention and modifications in its operation, it was pointed out that the apparatus could function as a back torquecontroliing means for an unwinding reel adapted to maintain tension on the strip material as it enters a mill or other device employing rolls or the like, such as are indicated at l0 and II. The drawing accompanying this specification may be considered a complete disclosure. not only of the rewind device above-described, but also of an unwind device, or of an apparatus adapted to perform the functions of both an unwind and a rewind device. drawing as representing an unwind device and controlling means therefor, the reference numerals may be descriptive of the same elements of the apparatus with the following changes: reversal of power flow in the electric drive machines; reversal of potentiometer control for Considering the 25u-zuo iield 28 by means of the double-throw switch II; and, for stop-and-go movement, opening of switch I" and closing of switch ll (switches I4 and H4 reverse their functions in other words).
The strip I! may be considered as moving toward rolls II and II, unwinding from a reel II, and the tension'on strip material I! may be considered as eilectuated by regenerative braking in a generator II. Generator I! may be considered as supplying power to a motor II, the current input to motor 2| being controlled by the same devices already described, to maintain current at a constant value. Switch 30 is provided to reverse the eflect of potentiometer tap 38 and resistor 28, so that the strength 01 held ll will be increased upon any tendency toward strengthening of current in the loop circuit, to provide greater-back electromotive force in motor 2|. Thus the regenerative braking or back torque of generator I will be constant unless the excitation of generator I! is varied. The motor 2| may be considered as driving a generator 22 feeding into power mains L3, L4, and Lo, and the decreasing amount of back torque required on the coiler It to compensate for rundown may be effected by the aforedescribed photo-electric torque-controlling means. The photo-electric control means will be operated, in the same manner as described, to increase the resistance in circuit with the held it of the generator I! to cause generator I! to develop less back torque, thereby to compensate for the decreasing radius of unwind coil H. For operation in this manner the movement of cell 42 and rack 4| will be reversed to follow run-down rather than build-up.
While the invention has been described with respect to a dynamo-electric machine It coupled to the reel II, which mechanism is adapted to function as either an unwind or a rewind reel by mere reversal of the direction of power flow, the invention is not to be construed as limited to electrical torque-applying means for the reel It. It is within the scope of the above-described invention-to apply the photo-electric torquecontrolling means to other known or subsequently developed driving means and braking means, operable by mechanical, hydraulic, or pneumatic means and the like. It is pointed out that the photo-electric portion of the torquecontrolling device lends itself to various modifications coming within the scope of the present invention, and the particular form of device described is not to be taken to limit the scope of the invention. It is c plurality of photo-electric cells associated ith, or independent "ofroth'er 'optical devices could be used'io perform the function r indicatinrchan'gm'radius of c qi l I4, and of adius 'tbrfiimplied'thereto by suitable relays, control motors, or other devices.
Having thus described and explained my invention and its mode of operation, I desire it to be understood that the apparatus described was selected merely-for the purpose of illustration, and that numerous variations in the form and arrangement of parts shown and described herein may be made without departing from the nature and scope of my invention.
1. An apparatus for handling strip material and the like comprising a reel, driving means for said reel, means for adjusting the torque on said reel, a stationary source 01' radiant energy disposed and adapted to emit a beam of radiations across said reel, means responsive to radil ations impinging thereon from said source disposed to receive and sense a small increment of the radiations of said beam and adapted to have movement across said beam of radiations to follow change in radius of material on said reel, means for moving said radiation responsive means as aforesaid in synchronism with the adiustment of said torque-adjusting means, and means connecting said radiation responsive mean and said torque-adjusting means, said radiationresponsive means and said connecting means being adapted to actuate said torque-adlusting means in response to progressive change in interception of the increment of radiations sensed by said radiation responsive means caused by change in radius oi material on said reel.
2. An apparatus for handling strip material and the like comprising a rewind reel, an electric motor operatively connected with said reel, an adjustable current regulator for maintaining a selected constant current in the armature of said motor, an adjustable rheostat for varying the strength of the held of said motor, driving means for said rheostat, a stationary source oi light disposed and adapted to emit a beam of substantially parallel light rays across a space to be occupied by material on said reel, photoelectric means disposed to receive and sense a small increment of the rays of said beam and adapted to have movement across said beam 0! light rays to follow build-up of material on said reel, means for moving said photo-electric means as aforesaid in synchronism. with the adjustment of said rheostat through said driving means therefor, and electrical means connecting said photo-electric means and saidrheostat driving means, said photo-electric means and electrical connecting means being adapted to actuate said rheostat driving means in response to progressive change in interceptionof the increment of light rays sensed by said photo-electric means caused by build-up of strip material on said reel.
3. An apparatus for handling strip material and the like comprising an unwind reel, an electric generator operatively connected with said reel, an adjustable current regulator for maintaining a selected constant current in the armature of said generator, an adjustable rheostat for varying the strength of the field of said generator, driving means for said rheostat, a stationary source of light disposed and adapted to emit a beam of substantially parallel light rays across a space to be occupied by material on said reel, photo-electric means disposed to receive and sense a small increment of the rays of said beam and adapted to have movement across said beam of light rays to follow run-down of material on said reel, means for moving said photo-electric means as aforesaid in synchronism with the adjustment of said rheostat through said driving means therefor, and electrical means connecting said photo-electric means and said rheostat driving means, said photo-electric means and said electrical connecting means being adapted to actuate said rheostat driving means in response to progressive change in interception of the increment of light rays sensed by said photo-electric means caused by run-down of material on said reel.
4. An apparatus for handling strip material and the like comprising a rewind reel, driving means for said reel, means for adjusting the torque on said reel. reversible driving means for l-JU IIIIII Il-II