US2535352A - Loop controlled variable-speed drive - Google Patents

Description

Dec. 26, 1950 D. A. CUMFER LOOP CONTROLLED VARIABLE SPEED DRIVE 3 Sheets-Sheet 1 Filed June 1, 1945 5 jmldfam Dec. 26, 1950 D. A. CUMFER LOOP CONTROLLED VARIABLE SPEED DRIVE 3 Sheets-Sheet 2 Filed June 1, 1945 4 ilflrtttil I Dec. 26, 1950 v D. A. CUMFER LOOP CONTROLLED VARIABLE SPEED DRIVE 3 Sheets-Sheet 3 Filed June 1, 1945 Patented Dec. 26, 1950 UNITED STATES PATENT OFFICE Loor CONTROLLED VARIABLE-SPEED nmvn Donald A. Cumfer, Elmhurst, 111., assignor to United States Gypsum Company, Chicago, 11]., a corporation of Illinois Application June 1, 1945, Serial No. 597,123

4 Claims. 1

This invention relates to apparatus for the continuous processing of web material in connection with which power-driven rolls (draw, feed or pull) are usually employed for moving the web, more particularly to apparatus for maintaining desired conditions of slack or tension in the web between two successive sets of rolls, and it is an object of the invention to provide improved apparatus of the character indicated. v

In the processing of web material it has been usual to maintain the peripheral speeds of the draw, feed or pull rolls at substantially the speed necessary to pass the same number of feet per minute through each of the sets of rolls. thereby theoretically to insure that the web will progress at uniform speed throughout the processing range.

However, many factors enter into such processing to cause the web to progress at variable speeds through the processing units irrespective of the maintenance of said feeding rolls at a predetermined speed. Such factors particularly are encountered in the processing of a web of roofing material foundation such as felt. When felt is processed into roofing material, the thickening of the web by progressive saturating, coating and surfacing conduces to such increase of thickness as to interfere with the speed which otherwise would be expected to be maintained at various feeding or drawing rolls. Moreover, webs of all kinds stretch during processing, thereby adding another unpredetermined factor. Finally, one frequent cause of web slippage on feed rolls, with consequent failure of the latter to be able to maintain the progress of the web at predetermined speed, arises from the surface of the web becoming slippery by reason of the processing applied thereto at various points.

It has heretofore been suggested that the variable speeds of the web as it progresses through the processing unit could be regulated to prevent undesirable conditions and/ or stresses in the web by utilizing various variable speed changing devices. However, most of these latter are manually operated and require constant attention. This is particularly true when it is desired to maintain tension on a web extending between two feeding or pulling units where each of the units is capable of positively gripping the web as it leaves one unit and enters a succeeding unit. Under the last indicated conditions, if the entering rolls of one unit pull the web faster than it is fed from the last rolls of the preceding unit, the tension on the web will eventually exceed its tensile strength whereupon it will rupture or break.

Again, and especially frequently in connection with processing of web materials into roofin materials, it is required to set up a slack loop between two sets of draw, feed or pulling rolls and to maintain the size of this loop between two rather definite dimensional limits. Under these conditions it is exceptionally dilicult to insure automatically that the web materialiwill be maintained in a loop of proper dimensions between the two sets of rolls. So far as aware, such slack loops are now maintained between units by employing manually controlled variable speed devices of some kind. These devices encompass the necessity of manual operation and accordingly require that an operator maintain constant vigilance to insure that the slack loop continues within the dimensional limits imposed by the operating exigencies. When the operator notices that the loop is beginning to lose, 1. e., that the amount of material in the loop is decreasing, the feed rolls are speeded up whereupon the loop gains material. However, this speed-up causes a continued gain even after the desirable 100p dimension is attained. The operator then must again manipulate the controls to retard the speed of the material feeding devices, and in a short time the loop again begins to lose and the entire operat'mnal cycle must be repeated. Not only does such manual control require the constant vigilance of a trained operator to insure maintenance of proper operational loop dimensions, but it is also true that these loop dimensions are usually securable only by manipulating some sort of speed-changing devices directly in connection with the feed rolls, which with prior devices introduced a burdensome factor of expense and material.

This last shortcoming is also present in all of the quasi or manual assistance semi-automatic controls which have been proposed in connection with such loop maintenance. However, even with prior devices where the control is effected theoretically automatically th speed changing devices operating in connection with the feed rolls are heavy, involving the use of heavy pulleys or disks connected by belts or chains. Thus, whenever the speed changing device is brought into operation it is necessary to accelerate the heavy masses thereof and after the desired loop dimensions are attained, it is necessary to apply a large braking force to slow down and stop these masses. Consequently, the clutch gripping surface which effects starting of the speed changing mechanism and the braking surface which effects stopping thereof are subject to heavy wear. Furthermore, the parts of the speed changing mechanism directly connected to the feed rolls stop and start whenever the iced rolls are started and stopped, which may occur frequently, and thus in addition to the load on the clutch and brake mechanisms to start and stop the feed rolls, there is the load of a portion of the speed changing mechanism.

Accordingly it is a further obJect of the invention to provide improved apparatus of the character indicated that is simple, easy to use, small. and light in weight.

It is a further object of the invention to provide improved apparatus .of the character indicated that is completely automatic in operation.

It is a further object of the invention to provide improved apparatus for changing the relative speeds of successive rolls in web or material feedin apparatus.

It is a further object of the invention to provide in material feeding apparatus having a pair of rolls between which material is fed an improved process for varying the material feeding speed of one or both of said rolls.

According to one form of the invention, apparatus for controlling the relative speeds of two ad acent rolls is provided including speed varyin means adapted to be driven by one of the rolls, means for driving the other of the rolls from the speed varying means, and means responsive to a condition to be regulated for controlling the speed varying means. More particularly, there is provided in material feeding apparatus having at least two rolls between which material is fed, the combination of means for maintaining a predetermined amount of material between the sets of rolls including means for varying the speed of one of the rolls and a reversible motor for operating the speed varying means. Electrical means responsive to variations in the predetermined amount of material are provided for energizing the reversible motor along with time delay means for delaying changes in the motor energization effected by the responsive means.

For a more complete understanding of the invention reference should now be had to the acconipanying drawings, in which:

Fig. 1 is a side-elevational view of winding and looping apparatus embodying the invention;

Fig.2 is a top plan view of the apparatus shown in Fig. 1;

Fig. 3 is a somewhat enlarged sectional view taken substantially in the direction of the arrows 3-3 of Fig. 2;

Fig. 4 is a somewhat enlarged fragmentary view taken substantially along the line |-4 of Fig. 2;

Fig. 5 is a wiring diagram of the control system embodied in the invention;

Fig. 6 is an elementary wiring diagram illuscrating the manner of operation of the control system; and r Fig. '7 is a sectional elevatlonal view of a relay shown schematically in Fig. 5.

Referring more particularly to the drawings, the invention is shown embodied in web-processing apparatus including a winder l0 and a looper H.

The. looper H is a well known piece of ap paratus for forming loops l2 of the material being processed andconveying them from the point of formation to the point of utilization. For example, the loops l2 may be of roofing material having a coating of wet substance applied thereto and are being conveyed through a drying oven or treating chamber to the winder III for winding on a roll or mandrel. The looper H is shown somewhat schematically as comprising a series of hangers l3 spaced apart a sufficient distance to support loops l2 of material between them, the hangers being supported upwardly from the floor by a suitable framework or guide shown by the line II. The hangers ii are moved along the guide II by any well known means (not shown) to convey the loops l2 from one end of the looper toward the other. When any loop l2 arrives at the end of its travel, 1. e., the plate l5 ending the looper, the particular hanger is held stationary while the material is pulled out of the loop following which another hanger moves into place to have the associated loop of material removed, as is well understood by those skilled in this art, this process continuing as long as desired.

At the end' of the looper adjacent the plate ii there is a framework exemplified by the vertical columns l6 and II from which extend the brackets l8 and I9. Supported on the brackets by means of suitable bearings are the looper exit rolls 2| and 22 which feed or pull the web material out of the looper, the lower roll 22 having a sprocket 23, keyed or otherwise attached to its shaft for driving the roll 22. The material is fed between the rolls 2| and 22 and thus the roll 21 is spaced away from the roll 22 a distance so as to exert sufficient force on the material whereby driving only the roll 22 will move the material. Spaced directly behind the exit rolls is an idle guide roll 24 for supporting the web material away from the plate l5 and feedin it to the exit rolls 2| and 22 as it leaves the looper H.

The construction of the looper II is shown schematically since it is exemplary of a variety of forms of apparatus used in processing web materials, the invention having application to any such apparatus including two parts between which it is desired to maintain a slack loop of predetermined dimensions or other condition of the material such as the tension therein. Apparatus of this character commonly has rolls feeding the web material out of one part thereof, and also has rolls feeding the material into the other part thereof. Between these rolls the slack loop or tension, for example, is maintained. As part of the looper H the exit rolls 2| and 22 have been shown and described beyond which a slack loop is to be maintained as will become clear as the description proceeds.

The winder III is mounted on a framework 20 made of structural members such as I-beams supported on a suitable foundation, the framework 20 also supporting a, winder drive mechanism 25.

The winder drive mechanism 25 comprises a motor 28, a speed reduction gear 21 driven by the motor and a pulley 28 through which the winder I 0 is driven, the reduction gears being driven by any well known means such as belts 29, for example. The winder I0 includes a frame 3| supporting feed and guide rolls, a mandrel 32 on which the web material is wound, a roller table 33 upon which the roll of wound material is ejected when completed and a synchronizing mechanism 34 for varying the rotative speed between the feed rolls of winder l0 and exit rolls 2! and 22 of looper II. The winder In is mounted on the supporting framework so that the web material comes out of the looper and enters the winder forming a slack loop therebetween, the material being fed directly into the winder. Since the slack loop must necessarily hang down between the looper and the winder an idle guide roll 35 is provided on the framework 20 to guide the material to the winder feed rolls.

The winder frame ll extends upwardly from aaaaasa framework 23 so as to support the feed and guide rolls above the latter framework and in a proper position to receive the web material. At the forward end of the winder there is a guide roll 36 over which the web passes as it enters the guides 31 spaced apart the width of the material being fed so as to guide it and prevent its moving from side to side. The guide roll 36 is mounted in hearings in frame 3| and is not power driven, the weight of the material thereon being sufficient for this purpose. Two pairs of vertically spaced feed rolls are provided and supported in bearings in frame 3|, the feed rollsto the mandrel 32 upon which it is wound, the

mandrel also being driven through gears (not shown) from the pulley 43. The table 44, the space between feed rolls of each pair thereof and the guide roll 36 Meat the same height of! of the frame 26 so the web material may feed through the rolls and onto the mandrel substantially in a straight line. Laterally displaced from and in line with mandrel 32 is the roller bed 33 which comprises a series of rollers 45 mounted in a frame so that as the completed roll of material is taken from the mandrel it isrolled away on the rolls 45 in a simple and expeditious fashion.

In order to drive feed rolls 33, 39. and 4|, 42, the shaft 46 and the pulleys 41 and 43 mounted thereon are supported in suitable bearings on the upright columns l6 and I1. The pulley 41 is mounted directly in line with the pulley 23 and a belt 49 passes thereover. The pulley 43 is mounted directly in line with pulley 43 and a belt passes over these pulleys. Accordingly, when power is supplied to the motor 26 the feed rolls are driven from the shaft thereof through the belts 29, reduction gear 21, pulley 23, belt 49, pulley 41, shaft 46, pulley 43, belt 5| and the pulley 43 and web material between the rolls 33, 39 and 4|, 42 would be fed therethrough and wound on the mandrel 32.

The looper exit roll 22 is driven by means of a chain 52 passing over sprocket 23, the chain being driven from the winder feed roll 39 as will be described so that there is a direct drive between the winder drive rolls and the looper exit rolls. In this manner, the relative rotative speeds of these rolls is always known and fixed, and is not subject to random variations, the ratio of these rotative speeds being fixed at any desired value. For providing a driving connection between the looper exit rolls and the winder feed rolls and for varying the speed between these groups of rolls, the synchronizing device 34 is mounted directly on the shaft 53 of -and rotating with the lower winder feed roll 39. Referring toFig. 3 it will be seen that the synchronizing device is a differential gear mechanism by means of which a component of speed may be added to or subtracted from the chain 52 driving the looper exit rolls.

The synchronizing device includes the shafts 53 and 54, the ring gear 55 and the drive gears 56, 51, 58 and 59. The ring gear 55 is mounted to rotate on the shaft 53 on a bearing including the bushing 63 and the rollers 6|, the rollers bearing directly on the shaft 53 and being held in place by means of the retainer 62. Rigidly bolted to the ring gear 55 is a yoke or bracket 63 winder and is provided with circular flanges or which is spaced away from the gear 55 and extends substantially thereacross to support one end of the shaft 54, the yoke being provided with a hole through which the shaft 53 passes as shown. The outer end of the yoke 63 has an opening into which the shaft 54 is received, the rollers 64 forming the necessary bearing and the retainer 65 being provided to hold the rollers in place. The shaft 54 is prevented from moving toward the right by a washer 66 bearing against the yoke, the washer being held to the shaft 54 by the bolt 61. Keyed to shaft 53 between the yoke 63 and the gear 55 is the gear 56, and meshing with the gear 56 is the gear 51 which is keyed to the shaft 54. The shaft 54 passes through a hole in ring gear 55 and is supported therein by a bearing including the bushing 63 and the rollers 69, the rollers being held by the retainer 1|. Rotatively mounted on the shaft 53 adjacent the gear 55 on the opposite side thereof to the gear 56 is the gear 59, the gear 59 being mounted on sleeve bearing 12. Meshing with gear 59 and keyed to shaft 54 is the gear 53 which is mounted against the bushing 63. The shaft 54 is held from moving toward the left by a washer 13 bearing against the gear 53 and bolted to the shaft by the bolt 14. Keyed to the gear 59 so as to rotate therewith and concentric with the shaft 53 is the toothed sprocket 15. The sprocket 15 and the gears mounted on the shaft 53 are held thereon by the collar 16 which is held to the shaft 53 by the setscrew 11.

Assuming that the ring gearlis held stationary, as will be made clear, and assuming further that the shaft 53 is rotating counterclockwise (l. e., the roll 39 is rotating and the winder is in operation), the gear 56 will rotate counter lockwise since it is keyed to the shaft 53. Since tare ring gear and shaft 54 are stationary, the gear 51 rotates clockwise by virtue of its meshing with gear 56. Consequently, the shaft 54 rotates in its bearings in the yoke and the ring gear and rotates the gear 53 also keyed to the shaft 54 in a clockwise direction. The rotation of the gear 58 in a clockwise direction rotates the gear 59 meshing therewith in a. counterclockwise direction, and by virtue of the keyed connection between the gear 59 and the toothed sprocket 15 the toothed sprocket rotates counterclockwise. Therefore the chain 52 engaging the sprocket 15 rotates the sprocket 23 and the looper exit roll 22 counterclockwise. Thus it is seen that the looper exit rolls are driven through a nonslipping connection from the winder drive rolls and accordingly the normal ratio of the rotative speeds between these rolls may be fixed at any value and maintained thereat. The rotative speed of roll 22 relative to the rotative speed of roll 39 is determined in part by the ratio of gears 56 and 51 and the ratio of gears 53 and 59, and in part by the ratio of the sprockets 15 and 23. These ratios may be of any desired values. and in a particular case, such as between a winder and a looper of the character described, and for web material such as roofing, the ratio of gear 56 to gear 51 may be three-quarters, and the ratio of the gear 53 to the gear 59 may be unity. Therefore, the sprocket 15 rotates at three-quarters of the speed of roll 39. The sprocket 23 may have the same number of teeth as the sprocket 15, and hence the roll 22 rotates at three-quarters of the speed of the roll 39. Ordinarily the number of feet of material fed out of the exit rolls 2| and 22 are the same as the number of feet of material fed into the rolls 38 and 88. In the particular example given, for example, as one instance of use, the rotative speed of the roll 22 is three-quarters that of roll 88, and thus the diameter of the roll 22 is substantially four-thirds that of roll 88. p

In the operation of the winder and looper, a sleek loop 88 of material is maintained therebetween so that the winder will have suflicient material to wind without placing tension thereon. The loop becomes longer or shorter, due to conditions already pointed out, and to maintain it between desired limits the ring gear 55 of the synchronizing device 84 is arranged to be rotated in either direction.

Referring to Figs. 1 and 2, and particularly to Figs. 3 and 4, there is shown a worm gear 18 engaging the teeth of ring gear 55, the worm gear being supported in bearings 18 and 8| on the bearing bracket 82. The worm gear is'ooupled to the shaft of the reversible motor 88 supported on the bracket 84. The motor 82 is a three-phase alternating current motor and is reversible by reversing any two of the power leads connected to it, as will be more fully pointed out, but it will be apparent that other motors, for example direct current motors, may be used. When the motor 83 is not operating the worm gear is stationary and hence ring gear 55 is stationary, as pointed out before in this specification, for normal operation.

To explain the functioning of the synchronizing device for shortening or lengthening the loop 88, it is assumed that the roll 38 is stationary and the loop has a certain length. In the first instance it is further assumed that the loop has become short and it is necessary to lengthen it. This is accomplished by rotating the roll 22 faster than its usual speed so as to feed more material into the loop. Therefore, the sprocket must rotate counterclockwise to rotate sprocket 28 counterclockwise (the sprockets are assumed stationary so far as the regular drive is concerned). Accordingly, the motor 88 must be energized to rotate the ring gear 55 counterclockwise (i. e., same as the regular rotation of the roll 88) Also for purposes of explanation, it is assumed that the ring gear has rotated one complete revolution.

After one revolution of ring gear 55, the shaft 54 and gears 51 and 58 have made one complete revolution about the shaft 58. In addition to this revolution the gear 51 has rotated about the shaft 54 three-quarters of a revolution due to its meshing with stationary gear 58 (the ratio of gears 58 and 51 is three to four). The rotation of gear 51 about shaft 54 has been counterclockwise and hence the gear 58 has rotated about the shaft 54 three-quarters of a revolution in a counterclockwise direction. If the gear 58 had been stationary so far as shaft 54 is concerned, and had been rotated around the shaft 53 by virtue of the ring gear carrying the shaft 54 around with it, the gear 58 would have made a complete revolution in a counterclockwise direction because the gears 58 and 58 would have been locked together. However, since the gear 58 is rotating around the shaft 54, the gear 58 rotates a lesser amount by the amount the gear 58 rotates. Thus since the gears 58 and 58 are of the same size and the gear 58 has rotated three-quarters of a revolution about the shaft 54, the gear 58 has rotated onequarter of a revolution counterclockwise. Consequently, the sprocket 15 and roll 22 have rotated one-quarter of a revolution counterclockwise and have added a number of feet of material to the loop '88 equal to the distance the circumference of roll 22 moves in one-quarter revolution. In the event it is necessary to shorten the loop 88, worm 18 is rotated in the reverse direction by the motor 82 and the sprockets 15 and 28 rotate to turn the roll 22 in a clockwise direction and thus hold back material from the loop to shorten it. In the actual operation the rolls 88 and 22 are already rotating, and rotating the gear 55, as explained, speeds up or slows down the roll 22 over an interval of time. That is, a

component of speed is added to or subtracted from the speed of the roll 22.

It is contemplated by the invention that the dimensional limits of the loop be automatically governed as desired, without the intervention of an attendant. To effectuate this intention the feed chute is arranged at the exit of the looper and supports three limit switches 88, 81 and 88 which control the power supply to motor 88 to control its operation and its direction of rotation. The feed chute 85 extends at an angle to the looper so that the loop of material lies thereon in its movement and due to its weight holds the operating arms of the limit switches 88 and 81 in the necessary initial positions.

Power is supplied to the motor 83 from a threephase, sixty cycle source L1, La, La, through a manual control box indicated by the broken line 88 and an automatic control box indicated by the broken line 8I through circuits to be described. The control box 88 includes a three contact switch 82 and the fuses 83, 84 and 85 one of which is in each of the lines L1, L2, and L3, to protect the equipment in the event of a short circuit. The control box 8I includes two contactors 88 and 81 for controlling the direction of operation of the motor 88, two motor overload relays 88 and 88 and circuits interconnecting these elements and the motor.

The contactor 88 is of a well known type having the pairs of normally open contacts I8I, I82 and I83, and an operating coil I84 which maintains the contacts closed only so long as the coil is energized. The contactor 81 is substantially identical to the contactor 88 and includes the pairs of normally open contacts I85, I88, and I81, and an operating coil I 88 which maintains the contacts closed only so long as the coil is energized. Upon de-energizing the coils I84 and I88 the contacts operated thereby open. The overload relay 88 includes the normally closed contacts I88 and the resistor II8, the contacts being adapted to be opened by a thermally responsive element which may be the element bridging the contacts or a separate element when the temperature developed by the resistor II8 becomes too great. Similarly the overload relay 88 includes the normally closed contacts I I2 and the resistor I I3, the contacts being adapted to be opened by a thermally responsive element when the temperature developed by the resistor II3 becomes too great. The overload relays 98 and 88 control the power supply to coils I84 and I88 of the contactors 88 and 81 to open them when an overload occurs.

With the switch 82 closed, power will be supplied by closing the contacts I8I, I82 and I83 through the following circuits to the motor 83 to operate in a direction to lengthen the loop 88: From L1 through conductor II4, conductor II5, contacts I88, conductor H8 and conductor III to the motor. From Lo through conductor II 8,

conductor 3, contacts I02, conductor I2I, resistor H and conductor I22 to the motor. From L: through conductor I23, conductor I24, contacts IOI, conductor I25, conductor-l28fresistor H3, and conductor I21 to the motor. Power is supplied to the motor 83 to operate in a direction to shorten the loop 80 through the following circuits by closing the contacts I05, I08 and I01 (the contacts IOI, I02 and I03 beingopen). From Ll through conductor I I4, contacts I01, conductor I28, resistor H3 and conductor I21 to the motor. From L2 through conductor II8, contacts I08, conductor I28, conductor I2I, resistor H0 and conductor I22 to the motor. From In through conductor I23, contacts I08 and conductor II1 to the motor. The terminal of the motor connected to L2 remains the same in each of the described situations and the terminals of the motor connected to L1 and La are reversed thereby reversing the motor rotation as is well understood.

The coils I04 and I08 of the contactors 88 and 91 respectively are supplied through the time delay relays I 30 and I 3| which are in turn controlled by the limit switches 81 and 88 respectively. The relay I30 is of the well known dashpot time delay type including a pair of contacts I32, an operating coil I33 and a dashpot device I34 for delaying the opening of the contacts after they have once closed and the co lv energization is removed. Similarly the relay I3I includes a pair of contacts I35, an operating coil I38 and a dashpot time delay device I31. I Referring more particularly to Fig. 1, there is shown a sectional view of a time delay relay such as relays I and I3I comprising a chamber I38 having a diaphragm dividing it into two parts. On one side of the diaphragm there is a poppet valve I39 covering a relatively large opening so that when the diaphragm is pushed upwardly the air in that side of the chamber is pushed out without resistance. On the same side of the diaphragm there is a needle valve I which is ad- Justable to vary the size of an opening into the chamber. Thus when the diaphragm moves downwardly the valve I39 closes the opening associated therewith and a vacuum is created on the upper side of the diaphragm. The diaphragm moves downwardly slowly as air flows into the chamber through the opening controlled by the needle valve I4 I. By varying the position of the needle valve, the time delay is varied. On

the lower side of the diaphragm there is an operating arm I42 attached to a block I43 which is biased downwardly by a spring I44. The opening in the chamber below the diaphragm through which the arm I42 passes is sufficient in size so that relatively little resistance to the flow of air therethrough is experienced. The relay contacts are operated by a lever I50 actuated by the lug I45 on the block I43, and below the block I43 there is shown a coil I48 for initiating operation of the relay. The time delay produced is the result of the force of the spring I43 and the force of the vacuum above the diaphragm. Other means may be employed for producing a time delay such as escapement mechanisms or shortcircuited windings on the relay coils, for example.

The coil I04 is energized when the relay contacts I 32 are closed to pick up the contactor 88 through a circuit extending from one terminal S1 of a source of supply, through a fuse I41, conductor I48, conductor I48, contacts I32, conductor I5I, conductor I52, coil I04, conductor I53, contacts I00 and H2 in series, conductor I54, con ductor I and fuse I58, to the other terminal S:

of the source of supply. When the contacts I32 open the, coil I04 is de-energized and the contactor 88 drops out. The coil I08 is energized when the relay contacts I35 are closed to pick up the contactor 81 through a circuit extending from S1, through fuse I41, conductor I48, conductor I81, contacts I35, conductor I58, conductor I59, through coil I08, conductor I8I, conductor I 53, contacts I08 and I I2 in series, conductors I54 and I88 and fuse I88 to S2. Whenever the contacts I35 open, the coil I08 becomes de-energized and the contactor 91 drops out.

The coil I33 of the relay I30 is energized through a circuit extending from s1, through conductor I48, conductor I82, contacts of limit switch 88, conductor I83, contacts of limit switch 81, conductor I84, coil I33, conductor I85 and conductor I55 to S2. The coil I38 01' the relay is energized through a circuit extending from S1, through conductor I48, conductor I82, contacts of limit switch 88, conductor I83, conductor I88, contacts of limit switch 88, conductor I81, coil I38, conductor I88 and conductor I55 to S2.

Referring to Fig. 6, an elementary wiring diagram, it will be seen that the contacts of limit switch 88 are in series with the contacts of the limit switches 81 and 88. Consequently neither of the relays I30 and I3I may be energized when the limit switch 86 is open,i. e., there is no loop at all between the looper and the winder.

In the normal operation of the looper, winder and synchronizing device, the rolls 39 and 22 are rotating, the loop is maintained about at the position 80b and can move between the positions 800 and 800 before the synchronizer comes into operation. Normally when the loop is lying with one side on the chute with its lower end at 80b and the contacts ofthe limit switch 88 are closed, the contacts of the limit switches 81 and 88 are open. ,Referring particularly to Figs. 1 and 6, if the loop shortens to a point above the position 80a due to whatever cause, such as slipping of the material in the rolls, for example, the material uncovers the arm of the limit switch 81 which closes its contacts and energizes the coil I33 of relay I30 through the described circuit, the limit switch 88 being closed whenever the loop extends more than a short distance downwardly. The contacts I32 close, energizing the coil 104 to pick up contactor 98 and thereby energizing the motor 83 to effect operation of the synchronizing device to lengthen the loop as explained. As the loop lengthens by speeding up the roll 22 gradually, the loop comes into contact with the operating arm of the limit switch 81 and opens the contacts thereof, thereby de-energizing the coil I33. However, due to-the time delay in the relay I30, the contacts I32 remain closed for an interval thereby permitting the synchronizing device to continue lengthening the loop. The time delay in the relay I30 may be so adjusted that for ordinary conditions encountered the loop will lengthen to position 801) before the synchronizing device stops by the contacts I32 opening. If, while operating, the motor 83 is overloaded, either or both of the contacts I09 or II2 will open due to the resistors H0 and II 3 becoming hot and will de-energize the coil I32 if this has not already occurred and the motor 83 will stop at the end of the time delay interval.

If the loop lengthens out to a position at or beyond the position 800, the web material contacts the operating arm of the limit switch 88, closing the contacts thereof and energizing the coil I38 of the relay I3I through circuits already 11 described. This energizes the coil I Ill to pick up contactor 91 and energize the motor 83 which runs in the opposite direction to operate the synchronizing device to take material out of the loop as previously explained. As the loop shortens, the operating arm oi! the limit switch It is released, opens the contacts thereof and de-energizes the coil 6. The contacts I36 remain closed for an interval due to the time delay in the relay iii. The delay in the relay maj'y be so adjusted that the loop shortens to thepo'sition 86b for ordinary conditions encountered before the contacts I36 open and efifect stoppingoLthe synchronizing device. In this case also the motor 83 becomes overheated, the thermalov'er load relays 88 and 99 open their contacts J6! and H2 to de-energize the coil I36 if this has not occurred to stop the motor at the end of the time interval.

It may be desirable to vary the amount of material in the loop 90 while the winder i0 is stationary. This may be accomplished by manually actuating either the limit switch 61 or the limit switch 68. Thus if the contacts of limit switch 61 are manually closed, the motor 83 will be energized and will rotate the ring gear 55 in a counterclockwise direction. As already explained, when the ring gear 55 rotates counterclockwise, even though the drive roll 39' is stationary. the looper exit roll 22 will be rotated to feed material into the loop. 11' it is desired to shorten the loop 86, the contacts 0! the limit switch ll may be manually closed which will effect energization oi the motor as explained to rotate the ringv gear 66 in the clockwise direction to eil'ect ieeding of material into the loop to lengthen it even though the winder is stationary.

Thus the loop is shortened or lengthened in a progressive manner without rapid accelerations or decelerations of heavy rolls but by slowly and uniformly increasing or decreasing the speed of the looper exit rolls without the ministrations oi driving means connecting said feeding meansand' said 'izi n'pelling roller, means for angula rl'y sup- ;porti'rigbne side of said slack loop, a plurality oi spaced contact switches on said supporting means actuatable by contact with said supported side of said slack loop, and a motor controlled by. said switches for operating said differential gear whereby to control the speeds oi said impelllng roller to vary the length of the roofing felt in said slack loop.

2. The improvement as claimed in claim 1 in which there are three switches on the loop-supporting means so arranged that at the desired position of the bottom of the loop the two upper switches have their operating arms in contact with the roofing felt.

3. 'Ihe improvement as claimed in claim 1 in which there are three switches on the loop-supporting means, the operating arm of the uppermost switch being always in contact with the roofing felt irrespective of contact of said felt with the operating arms of the other twoswitches.

4. The improvement as claimed in claim 1 in which the impelllng roller is connected with the differential by means of sprocket chains and sprocket wheels.

DONALD A. CUW'ER.

REFERENCES CXTED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,256,286 Avery Feb. 12, 1918 2,043,354 Mallina June 9, 1936 2,108,767 Fitzgerald .Feb. 15, 1938 2,166,551 -Perry July 18, 1939 2,250,209 Shoults et a1 July 22, 1941 2,295,327 Bendz Sept. 8/1942

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