US2117878A - Guide control means for web material - Google Patents

Description

w ROSSREFERENCE EXAWH FIPSZIZ XR 2,117,878

May 17, 1938. P. E. FRIEDEMANN 2,117,878

GUIDE CONTROL MEANS FOR WEB MATERIAL Filed Aug. 24, 1934 4 Sheets-Sheet l WITNESSES: INVENTCSR 2 5 0 2 0 1 CROSS REFERENCE Emma May 17, 1938. P. E. FRIEDEMANN 2,117,373

GUIDE CON'i'F-OL MEANS FOR WEB MATERIAL Filed Aug. 24, 1934 4 Sheets-Sheet 2 WITNESSES: INVENTOR em/am z a U 2 U l L|\l-|UL Lulu llillll-l y 1938- P. E. FRIEDEMANN 2,117,373

GUIDE CONTROL MEANS FOR WEB MATERIAL Filed Aug. 24, 1934 4 Sheets-Sheet 3 WITNESSES: INVENTOR 5. yy. Maw

I. U V I. v L

May 17, 1938. E, ED M NN 2,117,878

GUIDE CONTROL MEANS FOR WEB MATERIAL Filed Aug. 24, 1934 4 Sheets-Sheet 4 INVENTOR Patented May 17, 1938 UNITED STATES PATENT OFFICE Patti E. Frierlemann, Company, East of Pennsylvania Wllkinsburg, Pa., assignor Westinghouse Electric 8; Manufacturing Pittsburgh, Pa., a corporation Application August 24, 1934, Serial No. 741,266

1'! Claims.

My invention relates generally to the control of traveling webs to maintain them in a desired operating position.

More particularly my invention relates to control means for controlling the transverse movements, or position, of a strip of material with reference to certain elements of a machine moving the material in a certain general direction.

My invention is an improvement on the equipment disclosed and claimed in the joint application of Finn H. Gulliksen and Stephen A. Staege,

flied January 14, 1933, Serial No. 651,722, and relating to Wire guide control.

In the art of paper making, mechanical means are provided to maintain the Fourdrinier wire in a given position on the guide roll or rolls, but such devices require considerable actuating force from the wire with the result that the wire becomes frayed at the edges. Serious breakage may thps result, and what is equally as detrimental, the useiul liie of the wire is very materially shortened.

By the control apparatus I herein describe and claim in the claims hereto appended, the edge of the web, whether such web be a Fourdrinier wire, a single wire, a felt, a strip of paper in a printing press, drive belt, conveyor belt, or any other web, is not subject to wear.

It is an object of my invention to provide electric control means whereby the travel of awe'b in a machine may be kept in a substantially definite or predetermined path.

Another and somewhat more specific object of my invention is to provide a system of control for a machine moving a web of material in a certain general direction which system of control includes two groups oi elements cooperating with the web and cooperating with each other to restrict the lateral movement oi the web of material to a certain path oi travel when all the elements of both groups are in operative condition and which restricts the cooperative action of the web and control system to one group of elements when any one, several, or all oi certain elements of the other group of elements fail to thus nevertheless restrict the movements of the web within the desired path of travel.

Another object of my invention is the provision of electric control means whereby a web of material may be made to follow a given path even though a portion oi the control means may have become inoperative.

A more specific object of my invention is to provide two groups oi cooperating control elements, cooperatively related with a web of material moving in a certain general direction, adapted to restrict the lateral meanderings oi the web of material within certain limits, said control elements being designed to have their circuit arrangements changed by the failure of any one, several, or all, oi certain elements in one or the other group of elements so that the web cooperates only with the group of elements in operative condition and is thus nevertheless restricted to substantially the same path of travel, namely, its meanderings are restricted to substantially the same limits despite the failure of certain elements in a group of the control elements.

Other objects and advantages of my invention will become more apparent from a study of the following specification and the claims appended thereto when considered in conjunction with the accompanying drawings, in which:

Figure 1 is a ditic showing of a photoelectric system of control for maintaining a web of material in a given path;

Figs. 2 and 3 are diagrammatic showings of modifications oi my invention shown in Fig. l; and

Fig 4 is a diagrammatic showing of a modification of my invention utilizing a mechanically operable switching means to rearrange the circuits of my control system to accomplish the novel results of my invention.

Referring more particularly to Fig. 1, where a system of control is shown for controlling the lateral movements of a web, reference numeral l designates a guide roll which is but one, preierably the end roll, of a plurality of rolls, and which guide roll may be shifted in angular position about the pivot point 2 by a bearing shifting means 3 shown at the left oi the roll I and operated by the reversible motor 4. The axis of the roll will thus take various angular positions with reference to a given average position substantially parallel to the axes of other rollers, such as I. The shifting of the roll I will positively produce lateral or transverse movements of the web 8 during the travel of the web 6 which travel is produced by a main motor M, suitably controlled by a controller C. That is, normally the rolls-as represented by I are driven to move the web in a general direction as indicated by the arrow on the web, but the bearing shifting means 8 for the roll I will cause a positive transverse movement oi the web and the direction of such transverse movement will depend upon the direction of movement of the bearing 1 at of roll I.

In normal 0 ration ior printing presses, windthe left HUU log machines, and particularly in the art of paper making, the web of material, which, in the art of making paper, is usually a Fourdrinier wire, for some cause has the normal and usual habit of meandering, that is, of moving from the right to the left and the left to the right thus shifting its path of travel. This shifting of the path of travel has no natural limits, so that the web of material will run off the rolls and will be damaged or broken in the absence of some control means for restricting the lateral or transverse movements of the web. Meandering of the web of material within certain limits is, of course, permissible provided the limits set are within safe or desired operations. A

The rolls I and 5 may represent a pair of idler rolls, constituting parts of a paper making machine whereas certain other rolls not shown may be adapted to drive the web in the general direction indicated by the arrow on the web 6. However, as shown, a suitable main motor M is provided for driving the machine for operating the web, and this motorhas suitable starting control means C, but since neither the motor M, nor the control system of the main motor M in any wise in themselves constitute a part of this invention, none of these elements are shown in detail.

My invention as herein disclosed is adapted to a control system for shifting the bearing 1 of the roll I by suitable operation of the bearing shifting means Ithrough the reversible motor 4. To control the reversible motor 4 as a function of the lateral position of the web 6 I provide a pair of directional contactors 8 and 9 adapted to interconnect the motor 4 with a source of direct current designated by the buses l0 and l I, when the web has meandered from its desired path of travel an amount sufllcient to intercept the light emitted from the sources of light l2 and I3 normally falling on the photocells or photo-tubes l4 and IS. The light will, of course, be intercepted either for the light l2 or the light l3, since these lights as well as the photocells are spaced equal distances from the mid-line of the desired path of travel so that the web 6 has a permissible lateral movement determined by the distance of the edges of the web from the rays of light passing from the sources of light to the respective photocells.

The photocells l4 and I5 as well as the lights 12 and i2 and a pair of control relays 24 and 25 are interconnected with a pair of buses l6 and I1 energized with alternating current. The photocells and I5 are indirectly connected to buses I6 and I1 whereas the lights l2 and ii are connected directly across the buses l6 and I1. Whether or not these portions of the control circuit are connected exactly as specified is not important. It is sufficient to say that they are energized in a desired manner. The photocells l4 and I! are interconnected with a pair of electric discharge devices 20 and 2| and the actuating coils 22 and 23 of control relays 24 and 25. The interconnection of the electric discharge devices with the photocells is such that the output current namely the current in the actuating coils 22 and 22 of the control relays 24 and 25, respectively, is afunction of the quantity of light falling on the phototubes I4 and ii. In other words, when the web 5 intercepts the light falling on these photo-tubes, the current in the actuating coils 22 and 23 will be reduced so that these control relays 24 and 25 become deenergized.

The control relays 24 and 25 being normally energized will set up circuits when deenergized to start the reversing motor 4 in such a direction as to re-position 'the web 6 on the rolls l and 5 so that the particular phototube that may have been darkened by the web will again be subjected to the light of the source of light associated with the photocell. [For instance, if the web 6 intercepts the light from the source of light l2 so that the illumination on photocell i4 is decreased the current in the actuating coil 22 is decreased, and in consequence the directional contactor 8 is energized, causing the operation of the reversible motor 4 in such a direction that the bearing 1 is shifted to thus positively cause the movement of the web 6 toward the right. On the other hand, if the light falling on photo-tube I! from the source of light I! is intercepted by the web 6, the actuating coil 22 will be deenergized, setting up circuits for the directional contactor 8 to thus cause the motor 4 to'operate to shift the bearing 1 in such a direction that the web 6 is positively shifted toward the left.

From the foregoing general. statements, it is apparent that the web 6 may meander within certain limits, but as soon as one or the other of the photocells is darkened, circuits are established for operating the motor 4 to re-position the web to such a position that the light is no longer intercepted. Thereafter the web is free to have a transverse movement, the limits of which are determined by the positioning of the photocells l4 and I5 and lights l2 and [3 respectively cooperating with these photocells. If, however, a photocell, or a source of light, or an electric discharge device or two of these units or all three of these units should fail, it becomes clear that the particular edge of the web at which the failure of any one, several, or all of these units mentioned takes place, can no longer operate to properly control the motor 4 to maintain the web in the desired path of travel.

To increase the reliability, the safety, and efflciency of my system of control, and to eliminate the need for additional safety devices, I make provision for changing the control, should a failme of any one, several, or all of the units mentioned take place at one or the other side or edge of the web, to that side or edge where no failure or failures occurred. The change or transfer is effected by the cooperative action of the control relays 24 and 25, the contactor 26, and the master relay 21.

'A better understanding of theovel features of my invention can probably be had from a study of typical operations and cycles of operation for various actions or transverse movements of the web 2. In the circuit diagram shown in Fig. 1, switches 28 and 29 are shown as having been closed to energize the buses 16 and I1. Energizing circuits are thus established for the lights l2 andv l2, and the transformers I! and I. From the secondaries of the transformers both the photocells and IS, the two electric discharge devices 20 and 2| and the two actuating coils 22 and 22 of the control relays 24 and 25 are energized provided, of course, the web is in such a position that the light passing from the sources of light to the respective photocells is not intercepted.

In Fig. l, the web is shown as in the desired position, so that an energizing circuit is established from the left terminal of the secondary of transformer l8 through the actuating coil 22 of control relay 24, r istor l0, cathode 2! of the electric discharge d vice 20, past the control grid 32 to anode u, and back to the right terminal of the secondary of transformer II. The .capacitor 34 has one junction connected intermediate the resistor 30 and the cathode ii and the other junction connected intermediate the control grid 32 and the cathode 35 of the photo-tube I4. The anode 55 of the photo-tube is connected directly to the right terminal of the secondary of the transformer II. The circuit arrangement just explained for the electric discharge device, the capacitor and the phototube is known as a forward circuit, wherein the effective resistance of the photocell l4 and the amplifier tube or electric discharge device 20 in the output circuit, namely the circuit including the actuating coil 22 is a function of the illumination of the photocell l4.

A similar circuit is established for the actuating coil 23 of the control relay 25 which circuit may be traced from the right terminal of the transformer IQ of the secondary through the actuating coil 23, resistor 31, cathode 38, past the grid 39 to the anode 40 to the left terminal of the secondary of the transformer IS. The capacitor 4! has one junction connected intermediate the resistor 31 and the cathode 38 and the other junction connected intermediate the control grid 35 and the cathode 42 of the photocell l5. The anode 43 of the photocell I5 is connected directly to the left terminal of the secondary of the transformer IS. The actuating coil 23 of the control relay 25 is thus energized, and all of the contact members controlled by the control relay are in their actuated positions, .some of them being opened and others being closed. For the energization of the actuating coil 22 heretofore explained the control relay 24 caused certain of its contact members to be open and certain other of its contact members to be closed.

If the attendant wishes to start the control of the moving web 5 by the cooperative action of the web with the lights, the photocells and the electric discharge devices, which, in turn, control the control relays, he will actuate the starting push button 44 to close the stop switch 45 whereupon a circuit is established from the positively energized bus ill through the contact members 45 of the stop switch also controlled by the stop button 46 mechanically coupled to the starting push button 44, back contact members 41 of the time limit relay 4!, actuating coil 48 of the line contactor 50 to the negatively energized bus ll. Operation of the line contactor 50 closes the contact members 5| and certain line contact members in controller C. Closing of the contact members 5i merely establishes circuits for motor 4 when the respective directional contactors 4 and 5 are suitably energized should the web 5 darken one 'or the other of the photocells I4 and I5.

The closing of the contact members, which are really part of controller C, may provide for the starting of the main motor M operating the machine to move the web in the general direction indicated. However, such is not at all necessary, but contact members controlled by coil 4! merely deenergize certain control circuits for the main motor, thereby stopping the entire machine, should power fail on the buses l5 and H, or shouldany two of the electric units, namely the lights, photocells or the electric discharge devices, disposed on opposite sides of the web fail. Since neither the controller C nor the main motor M constitute parts of this invention, I believe it sufficient to schematically show these features.

After the operation of the line contactor 50, the two control relays 24 and 25, the directional contactors 5 and 5, the time limit relay 4., the contactor 28 and the master relay 2! will all remain in the positions indicated as long as the web moves along its desired path of travel, namely the path indicated by the arrow on the web 6.

Since the web 6 has the natural habit of meandering unlimitedly, it will naturally, sooner or later, intercept the light falling on one or the other of the photocells and establish an operating circuit for the reversible motor 4 to readjust the position of the bearing 1 for the roll I. Assuming that the web 5 meanders toward the left so that the light falling on the photocell I4 is intercepted, whereupon the bias on the grid 32 is changed so that the current in the actuating coil 22 is decreased by an amount sufficient to release the armature of the control relay 24. As soon as the armature of the control relay is released, contact members 53, 54 and 55 close and contact members 56 open. The closing of the contact members 53 establishes an energizing circuit for the upper coil 51 of the master relay 2! which thereupon closes its upper contact members 55. The closure of the upper contact members 55 can, however, establish no useful energized circuit at this time, since contact members 59 of the contactor 26 in series with contact members 58 are still open. The closure of the contact members 54 can also not establish any useful energized circuit at this time, since the contact members 60 of the control relay 25 in series with contact members 54 are still open.

The closure of the contact members 55, however, establishes a circuit from the energized bus l0 through the contact members 55 of control relay 24, contact members ii of control relay 25, the magnetizing coil 62 of the directional contactor 9 and conductor 63 to the energized bus II. The main or magnetizing 001152 of the directional contactor 9 being thus energized, the contact members 64 are closed whereupon a circuit is established from the energized bus I0 through resistor 65, the armature 66 of the reversing motor 4, field winding 61, conductor 68 and contact members 64 and 5! to the energized bus I I. The motor 4 is thus caused to operate to shift the bearing 1 in such a direction that the web 6 is positively caused to move toward the right. The shifting of the bearing 1 is continued until the web 6 is moved an amount suflicient to again permit the light from the source I! to fall on the photocell l4, whereupon the actuating coil 22 is again energized, the contact members 55 are opened, the magnetizing coil 52 is deenergized, and a short time thereafter the circuit for the motor 4 is opened at the contact members 54. No further shifting of the bearing thus takes place and the web is again free to move transversely in whatever direction it pleases. Thepositive shifting of the web toward the right is only far enough to again position it in substantially the average desired path of travel, the path indicated by the arrow.' If the web 6 again moves toward the left, the cycle just explained is repeated and the web is again caused to positively move toward the right.

that the motor 4 may not be operated too frequently for short intervals of time, the directional contactor 5 is of the time limit type. To provide for the necessary time constant, a neutralizing coil 58 is connected directly across the buses l0 and II through a resistor III. This neutralizing coil hasbut few ampere turns and is connected to act in opposition to the main magnetizing coil 52. Furthermore, the directional 5 In order that there may be no hunting and also ing coil 82 and the neutralizing coil 69, so that the armature 12 of the directional contactor 8 is returned in its non-actuated or open position a short interval of time after the opening of the contact members 5 by the reillumination of the photocell i4.

By reason of the time constant of the directional contactor I, motor 4 will of course operate for a short time after the light again falls on the photocell l4, so that the web may be shifted some small distance away from the pencil of rays that passes from the source of light l2 to the photocell l4.

If the time constant of the directional contactor 8 is such that the bearing 1 is moved more than was absolutely necessary, the web 6 will, of course, travel toward the right. If the web 6 travels towards the right, the light falling on the photo cell l5 may be intercepted, that is, the photocell I5 is darkened whereupon the energizing coil 23- is deenergized. It should be noted at this point, though, that an over-correction, that is, a time constant of the directional contactor 8 which would normally cause the motor 4 to shift the bearing to such a position-that the web would tend to move toward the right would not necessarily insure that the web would move towards the right. .The unequal distribution of the paper pulp on the Fourdrlnier wire may provide a greater tension at one edge of the web than at another, so that in spite of one operation of the directional contactor 9 the web may again move toward the left, in which case the cycle of operation above explained is repeated and the direc-- tional contactor 9 will be caused to operate a second and possibly even a third time. Sooner or later, however, the hearing I will be shifted by an amount sufficient that the web will, in fact, move toward the right.

If the beam of light falling on the photocell I! is intercepted by the web 6, the actuating coil 23 of the control relay 25 is deenergized with the result that the contact members I3, '0 and 14 are.

closed, and the contact membersji are opened.

cell l4, the contact members 52 were, of course. caused to be opened and in consequence the balanced master relay 2'! moved to the position shown in Fig. 1 thereby opening the contact members 58. 'I'he closing of the contact members 12, therefore, causes theenergization of the lower actuating coil II of the master relay 21, whereupon the contact members I4 are closed. Closing of the contact members 16 does, however, not establish any useful energizing circuit at this time, since the contact members 59 of the contactor 26 in series with contact members I! are open. 'lhe closing of the'contact members I also doesnot establish any useful energizing circuit at this time, since the actuating coil 22 will be energized when the web is at the right, thus the contact members 54 will be opened.

The closure of the contact members i4, however, establishes a circuit from the energized bus ll through the contact members It and 14 to the main or magnetizing coil 18 of the directional contactor .8 to the bus II. The energization of the main or magnetizing coil ll causes'the closing of the contact members 19 whereupon a circuit is established from the energized bus ll through the resistor 65, armature 66, held winding 80 and contact members 19 and SI to the energized bus Ii. The motor 4, being thus energized,

UKUSS Hill tKLNUt operates in such a direction that the bearing 1 is shifted in such a direction to positively cause the movement of the web 6 towards the left. The shifting of the bearing I will continue until light again falls on the photocell l5 and thereafter will continue for an interval of time determined by the time constant of the directional contactor 8.

The directional contactor 8 is similar in design in every respect to the directional contactor 8. The directional contactor 8 is thus provided with a neutralizing coil 8| connected across the buses l0 and il through the resistor 83 and a copper ring inductively related to both the magnetizing coil 18 and a neutralizing coil 8| aids in giving the directional contactor its time constant. However, both the directional contactors 8 and 9 are provided with spring assemblies 84 and 85, respectively, for accurately adjusting the time constants of these respective directional contactors.

As explained, the bearings I will be shifted so as to positively cause the web 6 to move toward the left. If the correction is more than suillcient the web will move toward the left and the motor 4 will be energized from the controlling action of the photocell l4 in the manner previously explained. If the correction is not quite sufficient or if the loading characteristics of the web are such that the web nevertheless moves toward the right the cycle of operation just explained is repeated until the web eventually moves toward the left.

From the discussion of the controlling action hereinbefore given, namely for the cycle of operation when the web is at the left as well as for the cycle of operation when the web is at the right, it should be apparent that in each instance when the bearing is shifted to positively drive the web away from the darkened photocell, the web again becomes absolutely free to meander in whatever direction it pleases and may meander back to its ilrs't position or may meander toward the opposite side. In any case, the desired path of travel for the web is maintained regardless of whether it receives its controlling action from the units, namely, photocell, light, and the electric discharge device on one side, or the units, the photocell, light and electric discharge device on the other side.

As long as all the mentioned units in the control system remain operative, there is nodanger of causing the web to move on the rolls I and 5. However, if ,a light should fail, or a photo-tube fail, or an electric discharge device fall, it is clear that no controlling action can be expected from that particular side at which any failure took place. Furthermore, with devices heretofore devised, if such failure took place, the web was driven of! positively atone side of the rolls. In

all of the devices of the prior art, this danger was minimized by additional independent safety devices and no provision was made to make the control equipment absolutely reliable. Paper mill operators and certain engineers recognizing that there is danger from failure of any one of the units mentioned, in consequence used photo-electrical control means only in addition to mechanical control means which would contact with the edges of the web should a failure of an electrical discharge device, a photocell or a light take place.

With my invention, such duplication of equipment to provide for safe operation is not necessary. My system of control, therefore, departs radically from other systems of control by making the equipment absolutely reliable as long as there be no total failure of power, or as long as no two of the electric units, light, photocell and electric discharge device, on opposite sides of the web, fail at the same time. It should be readily apparent how remote the possibility is of having two electric units fail at the same time on opposite sides of the web, particularly when I provide indicating means to indicate when any one of the units fails.

My system of control thus satisfies a real need because everyone who has had to deal with electrlc lights, photocells or electric discharge devices,

knows that these devices do occasionally burn ou or fail. The trade generally must have recognized that the photo-electric control systems heretofore devised were not suflicient, since they were always used in conjunction with auxiliary mechanical safety devices.

To clearly understand the novel features generally explained, it should be noted that if an electric discharge device, a photocell, or a light fails, the particular actuating coil associated with the unit or units that failed will become deenergized. Assuming that either the light l2, the photo-tube l4 or the discharge device 20 have failed, which, of course, means that no controlling action can be expected from the cooperative action of the left edge of the web with the units at the left edge. Such being the case, the actuating coil 22 is deenergized and in consequence contact members 53, 54'and 55 close, and the contact members 56 open. If, at the instant of failure the web be in the position shown, and the motor 4 not energized, then the closure of the contact members 55 will establish a circuit for the directional contaetor 8 in exactly the same manner as if the web 6 had intercepted the light falling on photocell l4. In consequence the web will be caused to move towards the right. Since, however, the actuating coil 22 remains deenergized, even though the web 6 may move towards the right sufilclently to intercept the light falling on the photocell i5, provision is made to nevertheless maintain the web 5 in the desired path of travel.

The closing of the contact members 53 causes the energization of the upper coil 51 of the master relay 21 which thereupon closes the contact members 58. when the web has moved toward the right and intercepts the light falling on the photocell l5, the actuating coil 23 is deenergized with the result that the contact members 14 are closed. which would normally establish the energizing circuit for the directional contactor 8, should no trouble have developed at the left side of the web. Since, however, some one of the three units at the left failed, the contact members 56 are open and in consequence the directional contaetor 8 is not energized through the contact members 14. The closure of the contact members 60 of the control relay 25, however, establishes a circuit from the-energized bus I0 through the actuating coil 86 of the contactor 28 and contact members 54 and 80 to the energized bus II. Operation of the contaetor 26 closes the contact members 58.

whereupon a circuit is established from the energized bus "I through contact members 58 and 58 andthe main magnetizing coil 18 of the directional contaetor 8 to the energized bus II. The motor 4 will thus be energized through the operation of the directional contaetorl and will operate in such a direction as to positively shift the web toward the left and the operation of the motor will continue for 'a definite interval of time, depending upon'the time constant of the directional contactor 8, after the light from the source of light I2 is no longer intercepted by the web 6 and thus falls freely on the photo-tube Ii. In other words, the operation of the motor 4 continues even though the contact members iii are opened to deenergize the actuating coil 86 of the contaetor 26. Since the actuating coil 86 is deenergized, the circuit for the main magnetizing coil 18 will be opened at the contact members 89, but, by reason of the time constant of the directional contactor 8, the contact members 18 will remain closed for a short interval of time.

The deenergization of the actuating coil 22, of course, closes the contact members 12, but since the failure of one of the units at the left caused the previous closing of the contact members 53. the master relay 2'! will have its armature in its upper position, namely the contact members 58 will be closed. The energization of the lower coil 15 of the master relay 2'! will therefore have no effect on the movement of the armature of the master relay 21. This is a well known operation of any relay, because a considerably smaller current is needed to maintain the armature of a relay in engagement with the core of its magnetic circuit than is required to actuate the armature when the magnetic flux has to act through an air gap. Since the armature of the master relay 2'! previously moved upwardly, the air gap is still greater than it normally is when the armature is held in its balanced position by the springs 88 and 89. There is thus no danger for the master relay 21 to make the wrong connection when the web has moved toward the right to intercept the the contact members ii to energize the main or magnetizing coil 2 of the directional contaetor 8 to cause the closing of the contact members 84 r in the absence of any mechanical interlock for the directional contactors. In practice, depending upon the size of the equipment, no mechanical interlock between the directional contactors is often needed, because the time interval during which both the contact members 84'and 18 are closed is comparatively short so that the reversible motor 4 would not tend to run away by the simultaneous energization of the fields 61 and 88 connected in opposition. This motor will be prevented from running away because soon after the closing of the contact members 64 the contact members I! open and the reversible motor 4 will be connected for rotation in an opposite direction to shift the bearing 1 so that the web will again be shifted toward the right.

To prevent the connection of the field windings 61 and 80 in parallel, the armatures l2 and 82 of the directional contactors 9 and 8, respectively, are interlocked by the interlocking bar 81, so that neither the contact members 54 nor the contact members 19 can be in circuit closing position at the same time. During normal operation the contact members 55, 86, 6i and 14 prevent the simultaneous energization of both directional contactors.-

' From the foregoing discussion it should be clear yum regardless of the direction in which the web may be meandering at the instant it is in the mid-position or the desired path of travel, if a I failure takes place at the left as assumed, the cycle of operation just explained is not changed by reason of the direction of meandering at the instant of failure. v

If the failure takes place when the web 8 is at the left and in such a position that normally 'IQUL the light falling on the phototube l4 would be intercepted, no change will, of course, take place in the position of the control relay 24, since this control relay will already be in its deenergized position by reason of the interception of the light at the left and the movement of the bearing 1 will of course be in such a direction that the web is shifted toward the right.

The only other remaining position of the web during a failure is at the right intercepting the light falling on the photo-tube l5 when some failure takes place at the left. If the web be at the right, the actuating coil 23 will, of course have energized the motor 4 to operate in such a direction as to shift the web toward the left. The instant the failure takes place at the left contact members 56 will be opened, and in consequence, the circuit for the magnetizing coil II will be open. It would thus seem, without an exact knowledge of the operation of the control devices, that the motor 4 would reverse its operation to shift the web toward the right even though the web 6 is already at the right. Such is, however. not the case if the web is at the right, actuating coil 23 is deenergized and any failure at the left deenergizes coil 22. The closure of the contact members 55 therefore cannot establish a circuit for the magnetizing coil 62 since the contact members ii are open.

The web 6 being at the right, contact members 13 will be closed, and in consequence contact members 16 will be closed. Furthermore, contact members 60 will be closed and at the instant of any failure at the left, contact members 54 are closed with the result that the actuating coil 86 of the contactor 26 is energized and contact members 59 close. Since both sets of contact members i! and 16 are closed, a circuit is established for the magnetizing coil 62. However, since the directional contactor 8 is still closed, has an inductive time constant, and is interlocked with the directional contactor 9 the motor '4 will continue to shift the web toward the left and such shifting will continue for-an interval of time sufficiently long so that the web will be shifted to no longer intercept the light falling on the photocell l5, whereupon the circuit for the actuating coil It is opened. The energization of the magnetizing coil 02 is thus not continued through the contact members 59 and 16, because the reenergization of the actuating coil 23 opens the contact members Ii with the result that contact members 58 are closed, and closes contact members 6|. The energization of the magnetizing coil 82 thus continues through the contact members 86 and I. The web is thus shifted toward the right and when again intercepting light falling on the photocell ll, contact members ill are closed and the directional contactor I is energized through the contact members 58 and II. The direction of travel of the web 4 will thus be controlled by the cooperative action of the photocell and source of light and the portion of the system of control disposed at the right edge of the tube.

The master relay 21 and the cooperative action of the other control elements has hereinbefore been described in considerable detail, assuming a failure of a light, a photocell or an electric discharge device, or any two or all of these devices at the left. If such failure takes place at the right. since the system of control is entirely symmetricaL'the controlling action will be exactly as hereinbefore discussed except that the web will be maintained in the desired path of travel with the coaction of the left edge of the web with UHUUU ilL-l L-Hl-lliUlthe photocell and the source of light and the portion of the system of control controlled by these units disposed at the left. It should be apparent from the foregoing explanations that regardless of the position of the web 8 and regardless of the side at which a failure takes place the web nevertheless will be maintained within its desired path of travel.

To apprise the attendant of the fact that a failure has taken place at one or the other side of the web, the contactor 26 is provided with the contact member 11 which, when closed by the simultaneous deenergization of the coils 22 and 21h energizes the light 90, which may be a red 118 t.

The closing of the contact member 11 also energizes the actuating coll SI of the time-limit device 4!. As long as no failure of at least a pair of units takes place one of the units being disposed on one side of the web and the other at the other side of the web, the contact member 11 will be closed intermittently and in consequence the energization of the coil 9| will be interrupted from time to time with the result that the contact members 41 will remain closed by reason of the delay effected by dash pot I02. If, however, certain units fail at both the right edge and the left edge of the web, or if the power fails on the buses i5 and H, the contact members 54 and 60 will remain closed indefinitely with the result that the time limit device 48 will open its contact members 41, thus deenergizing the actuating coil 49 of the line contactor 50, which thereupon opens the contact member ii. The opening of the contact member 5| deenergizes the motor 4 whereas the opening of certain contact members in controller C opens a circuit in the system of control for the main motor M of the machine to stop the entire In the modification shown in Fig. 2, the same elements shown in Fig. 1 are designated with the same reference characters found in Fig. 1 and elements shown in Fig. 2 that are similar to elements shown in Fig. 1, are provided with similar reference characters. However, the modification shown in Fig. 2 operates somewhat differently than the embodiment shown in Fig. 1. For instance, if the web 8 be in the position shown and meander toward the left to interce t the light falling on photocell i4 actuating coil 22 is deenergized and in consequence contact members 55 close, establishing a circuit for the actuating coil I82 of the directional contactor "9 through the contact member I of the control relay 2!. Operation of the directional contactor I" closes the contact members I thus energizing the motor 4 to shift the web toward the right.

If one operation of the motor 4 were to accomplish an insuiilcient movement of the web 8 toward the right, the cycle will be repeated until the web 8 does in fact move toward the right to intercept the light falling on photocell ii. When the light falling on photocell It is intercepted. the actuating coil ill of the directional contactor III is energized and contact members I'll are closed. The motor 4 is thus operated to shift the web i toward the left.

If any one of the units, the light II, the photocell or the electric discharge device 2| at the right fails, the actuating coil 23 will be deenersized and the web will be shifted toward the left until the light falling on photocell I4 is intercepted, whereupon contact members I are been suggested the contact members I88 and H8 are so positioned on the armature of the control relay 28 that the contact members I88 close before the contact members I18 close. Similarly the contact members I84 and I88 on the control relay 24 are so positioned that the contact members I84 close considerablyeariier than contact members I88.

It should be noted that the distance between the elongated contact fingers adJacent the contact members I84 and I88 is much less than the distance between the contact fingers adjacent contact members I88 and I18, respectively.

If there be a failure at the right and the web has been moved to the left sufllciently to intercept the light passing to photo-cell I4, contact members I84 and 88' close before contact members I88 close. 0011 I82 is thus energized ahead of the energization of coil I18.

when the failure is at the left, the web is, of course, shifted toward the right and when intercepting the light passing to the photo-cell I8 the coil 28 is deenergized. The contact members I88 and 88' close before contact members I18 close, with the result that coil I18 is energized ahead of coil I82. The mechanical interlock I81 further aids in preventing the possibility of improper operation.

By reason of the failure at the right, contact members I88 and I18 are closed and when the web intercepts the light falling on the photocell I4. contact members I84 close considerably ahead of the closing of contact members I88 and thus cause the operation of the contactor 28 to close the contact members 88', thereby establishing a circuit for the actuating coil I82 of the directional contactor I 88 through the contact members 88' and I18. Once the directional contactor I88 has operated, the mechanical interlock I81 prevents the operation of the directional contactor I88. It is therefore clear that the deenergization of the Jactuating coil 22 by reason of the interception of the light falling on the photocell I4 by the web 8 causing the closing of the contact members I88 will not cause the closing of the contact members I18 even though the contactor 28 is energized and its contact members 88' are closed. The, web will therefore be shifted toward the right until the actuating coil 22 is again energized whereupon actuating coil I82 will be deenergized, since the circuit for the contactor 28' is open at the contact members I84 and an energizing circuit is established for the directional contactor I88 through the contact members 88 and 14. tion will be very similar if a failure should take place at the left. In this modification, it is also entirely immaterial whether the web be at the side where the failure takes place and also immaterial whether the web be meandering in one or the other direction, or whether it be in its desired path of travel or at the side where no failure takes place. The control is nevertheless such that the web is maintained in the desired path of travel.

The cycle of opera-- In the modification shown in Fig. 2, the proper sequence of operation and cooperative action of the control relays with the contactor 28' was secured through a proper positioning of the contact members. A similar result can, however, be obtained by the use of suitable time limit relays. This use of time limit relays is shown in Fig. 3. The normal operation for the modification shown in Fig. 3 is in every respect similar to the normal operation for the modifications shown in Figs. 1 and 2. However, if a failure takes place'of any one of the units, light, photocell. or electric discharge device, at one or the other side of the web the cooperative action of the contactor 228 coacting with the time limit relays 88 and 84 and the control relays 24 and 28 rearranges the circuits so that the control is shifted to the side where no failure has taken place.

The time limit relays 88 and 84 are very similar to the time limit directional contactors 8 and 8 shown in Fig. l, and have a pair of magnetizing coils 218 and 282 and a pair of neutralizing coils 28I and 288 connected in series circuit relation with a resistor 218. If a failure takes place at the left, contact members 88 and H are closed, establishing an energizing circuit for the actuating coil I82 of the directional contactor I88 thereby closing the contact members I84 whereupon the motor 4 is operated to shift the web toward the right. Since a failure was assumed to have taken place at the left, contact members I88 are closed shunting the magnetizing coil 282, whereupon the contact members 288 are closed after a definite interval of time. If the web is moved an amount sufficient to intercept the light at the photocell I8, contact members 288 close whereupon contact members I88 close thus establishing a circuit from a bus I8 through contact members I88 and 288 to the actuating coil I18 of the directional contactor I88, with the result that the contact members I18 are closed. The web will thus be shifted toward the left and the time during which such shifting will take place is determined by the time limit relay 84 which will, of course, close its contact members 218 when the contact members I18 are closed by the interception of the light falling on the photocell I8. The time constant is chosen of sufllclent length that the web is shifted toward the left by an amount sumcient that the light will again fall on the photocell I8, and the magnetizing coil 218 is reenergized to' open the contact members 218. However, since contact members '88 and 8I are closed, the web will be shifted toward the right nevertheless.

The modification shown in Fig. 4 shows a mechanical scheme for rearranging the circuit connections so-that the control may be shifted to one or the other side in case of failure of certain elements of agroup of elements at one or the other side of the web. 'llhe control relays 24 and 28 are provided with dogs 88 and 88 for operating the switches 82. This operation being effected by the ooaction of the dogs '88 and 88 with the ends 81 and 88, respectively, of the bar 88. The switches 82 are held in the full line position shown by the spring I88. If a failure should have taken place at the left, the bar 88 will be held in the dotted line position with the result that the contact members 888 are closed.

A failure ofany unit at the left will, of course,

close contact members 88 and since the contact members 8| are closed, the directional contactor I88 will be actuated by the energization of coil I82. Operation of the directional contactor I88 closes the contact members I with the result that the motor 4 is energized to shift the web toward the right. I

As soon as the web has been shifted toward the right an amount suflicient to intercept the light falling on the photocell I5, contact members 60 are closed thus energizing the coil 2 of the contactor 226 and thus closing the contact members I59. A circuit is therefore estabh'shed from the bus III through the contact members I58 and 358 through the conductor 211, and actuating coil I18 of the directional contactor I". Contact members I19 are thus closed and motor 4 is energized to shift the web toward the left. When the light is no longer intercepted at the right, the contact members 60 open, and directional contactor I08 is thus deenergized and contact members BI closed thereby energizing the directional contactor I09. The web is thus maintained in its desired path of travel despite the fact that a failure of one unit has taken place at one edge of the web.

My system of control as hereinbefore explained thus controls the transverse movement of the web by indiscriminately calling for web movement control upon the control means at the sides of the web for one operating condition of the entire control system and by discriminately calling for web movement upon the control means at the sides of the web for another condition of the entire control system.

Viewed diiferently, my invention provides for a movement, of a given line longitudinally of the web, away from the outer limits of the desired path of travel of the web for one arrangement of the control and provides for a positive oscillatory movement, of the given line longitudinally of the web, within the outer limits of the desired path of travel of the web for another arrangement of the control, and wherein such different arrangements are automatically effected upon the failure of a certain element or elements, or units, in a group of a plurality of groups of units in the entire system of control.

Iam fully aware of the fact that other circuit arrangements and other mechanical schemes than the particular structures and arrangements hereinbefore disclosed may be devised by those skilled in the art to accomplish the novel results of my invention, particularly after those skilled in the art have had the benefit of the teachings embodied in the foregoing specification. However, I wish to be limited only by the appended claims and the pertinent prior art.

I claim as my invention:

1. In a system of control, having a plurality of elements, for a machinemoving a web of material longitudinally of itself and wherein the web is subject to move out of a desired path of travel, in combination, control circuits having a plurality of arrangements, means for moving the web so that a given line longitudinally of the web is moved away from the outer limits of the desired path of travel of the web for one arrangement of the control circuits, and means for positively oscillating the web, so that the given line longitudinally of the web moves within the outer limits of the desired path of travel for another arrangement of the control circuits, said control circuits including means for automatically changing from one arrangement of the control circuits to another arrangement of the control circuits by the failure of certain elements in the system of control.

75 2. In a control system for a machine operating on webs of material that are subject to meander unlimitedly from a desired path of travel, in combination, a plurality of rolls for supporting and causing a web of material to travel in a given direction, photo-electric means disposed adjacent the edges of the web, lights disposed to normally act on said photo-electric means but which cease to act on said photo-electric means when the web meanders to a position to intercept the light falling on said means, and roller-axisshifting means responsive to a certain operation of said photo-electric means when the light is intercepted at either side for causing the axis of one of said rolls to be disposed at an angle to the axes of the other rolls to thus shift the web away from the side at which the light is intercepted, and means responsive to a failure of either the light or the photo-electric means, or both, adapted to alter the control system so that said roller-axis-shifting means, in response to the portion of the photo-electric means not affected by the mentioned failures, will cause the axis of one of said rolls to be shifted back and forth to change its angle with reference to the axes of the other rolls to thus shift the web back and forth within the desired path of travel.

3. In a system of control for a machine driving a web in a given general direction and wherein the web, in the absence of travel control means, .moves transversely that is, meanders indiscriminately towards either side and out of the limits of a desired path of travel for the web, in combination, electric control means at the sides of the web adapted to be thus indiscriminately influenced in operation by transverse movements of the web for one operating condition of the system of control, and by reason of restrained meandering of the web to be discriminately influenced in operation by the transverse movements of the web for another operating condition of the system of control, motor means adapted to control the transverse movements of the web,

control circuits set up for said motor means by the electric control means when subject to indiscriminate influence by the web to cause said motor means to operate to prevent a certain line longitudinally of the web from moving beyond the outer limits of travel of the web, and control circuits set up for said motor means by the electric control means when subject to discriminate influence by the web to cause said motor means to operate to positively move the web to and fro so that said given line longitudinally of the web is maintained within the desired path of travel.

4. In a system of control for a machine driving a web in a given general direction and wherein the web, in the absence of restraining means, moves transversely, that is, meanders indiscriminately to either side and out of the limits of a desired path of travel for the web, in combination, electric control means at the sides of the web adapted to be indiscriminately influenced in operation by transverse movements of the web for one condition of the system of control and by reason of restrained meandering of the web to be discriminately influenced in operation by the transverse movements of the web for another condition of the system of control and motor means, controlled by said electric control means, adapted to control the transverse movements of the web.

5. In acontrol system for a machine operating on a web of material and moving said web in a given general direction, said web having the habit" 16 of moving laterally to thus depart from a desired path of travel of the web, in combination with, control means, responsive to a certain lateral movement of the web, disposed at each side of the web and adapted to reposition the web to the desired path of travel, said control means including means responsive to certain conditions of operation for restricting the controlling action tothe control means at one side of the web.

6. In a control system for a machine operating on a web of material and moving said web in a certain general direction, in combination, electric control means having a plurality of units disposed at each edge of the material, and control means subjected to the control of said electric control means and adapted to keep the web of material in a given path, said control means including means responsive to a failure of one unit of the electric control means at one edge regardless of which edge to make the control means subject to the electric control means none of whose units have failed, whereby the web of material is maintained in the desired path of travel despite the said failure of one unit.

7. In a control system for a machine operating on web material, photo-electric means disposed adjacent each side of the material, and control circuits and web-shifting means subject to the control of said photo-electric means for maintaining the edges of the material away from said photo-electric means, said control circuits including means responsive to a partial failure of the control system adapted to modify the operation -of said photo-electric means and alter the arrangement of the control circuits so that the webshifting means operates to maintain one edge of the web of material adjacent to one of said photoelectric means.

8. In a control system for a machine operating on web material and having a plurality of elements including electric control means disposed adjacent each edge of the material, control devices, controlled by the electric control means,

adapted to maintain the edges of the material away from the electric control means, said control 'devices including means, responsive to certain changes in operating characteristics of said electric control means, adapted to control the transverse movement of the web of material so that one edge thereof is maintained adjacent one of said electric control means.'

9. In a system of control for a machine moving a strand of material longitudinally of itself and wherein the strand has the habit of meandering out of a desired path of travel. in combination, two groups of control devices, coacting with the strand and with each other, adapted to restrict lateral meandering movement of the strand to a certain path of travel when all the devices of both groups are in operative condition and adapted to restrict the coaction of the strand to one group of devices when either any one, several or all the devices of the other group fail, to thus nevertheless restrict the movement of the strand within the desired path of travel.

10. In a system of control for a machine for moving a strand of material longitudinally of itself and wherein the strand has the habitof meandering out of a desired path pf travel, in combination; two control means, each includins. among other elements, a photo-cell, an electronic tube, and a light so disposed that the photo-cell may be subjected to the radiant energy emitted by the light, coacting with the strand and with each other so'ss to restrict the lateral meanderfrom a given or normal path of travel, in combi nation, web-actuating means for causing a normal movement of the web in the direction of its length, electronic means responsive to a predetermined deviation of the web in a given direction transversely of its normal movement to cause shifting of the web back to its normal movement, electronic means responsive to a deviation of the web from its normal path oi movement greater than said predetermineddeviation for stopping the operation of both the web-actuating means and the electronic means, and control means, comprising part of said electronic means, adapted, upon a failure of any one or several of certain elements of said electronic means to cause the web to be shifted back and forth within the range of the normal movement.

12. In a control system for a machine operating on a web of material to move the web in a certain direction longitudinally of itself and in which machine the web has the habit of effecting meandering transverse shifts, in combination, web shifting means adapted to cause the web to shift to and fro transversely of the general direction of motion of the web by a small amount, electronic means, responsive to a predetermined transverse meandering shift of the web, adapted to control said web shifting means to effect a compensative transverse shift .of the web in a direction opposite to the meandering transverse shift, and further electronic means and means, responsive to a failure of part of said electronic means, coacting to control said web shifting means to operate so as to positively shift the web transversely .of its movement over a small substantially fixed-range.

13. In a control system for a machine operating on a web of material to move the web longitudinally of itself in a given direction and in which machine the web has the habit of mean dering transverse shifts, in combination, web shifting means adapted to cause the web to positively shift transversely of its general direction of motion, electronic means, responsive to a predetermined meandering shift of the web, adapted to control said web shifting means to positively shift the web in a transverse direction opposite to said transverse meandering shift, further electronic means including control means responsive to the failure 'of a part or all of either of said electronic means to cause the particular electronic means, no parts of which have failed, to alone assume the control of said web shiftins mean and means, responsive to the electronic means no parts of which have failed, to so control the web shifting means to positively shift the web to and fro over a substantially predetermined range.

14. In a, control system for a machine operating on a web of material to move the web in a, given direction longitudinally of itself and in which machine the web has the habit of meandering from side to side, in combination, web shifting means adapted to cause the web to shift transversely of the general direction of motion of the web, and electronic means disposed just beyond the edges oi the web, responsive to a predetermined transverse meandering shift of said web, adapted to control the said web shifting means to positively shift the web away from the particular electronic means towards which the meandering shift took place, and control means responsive to the failure of a part or all of the electronic means at either edge of the web to cause the web shifting means to positively shift the web to and fro over a small distance so that the meandering transverse shifts of the web above a predetermined magnitude are prevented.

15. In asystem of control for a machine driving a web in a. given general direction and wherein the web, in the absence of travel control means, moves transversely, that is, meanders indiscriminately towards either side and out of the limits of a desired path of travel for the web, in combination, photo-electric scanning means at each side of the web adapted to be thus indiscriminately influenced in operation by meandering transverse movements of the web for one operating condition of the system of control, and by reason of restrained meandering of the web to be-discriminately influenced in operation by the transverse movements of the web for another operating condition of the system of control, motor means adapted to control the transverse movements of the web, control circuits set up for said motor means by the photo-electric scanning means when subject to indiscriminate influence by the web to cause said motor means to operate to prevent a certain line longitudinally of the web from moving beyond the outer limits of travel of the web, and control circuits set up for said motor means by the photo-electric scanning means when subject to discriminate influence by the web to cause said motor means to operate to positively move the web to and fro so that said given line longitudinally of the web is maintained within the desired path of travel.

16. In a control system for a machine operating on a 'iveb of material and moving said web in a giver?" general direction, said web having the habit of haphazardly moving laterally to thus depart from a desired path of travel of the web, in combination, with photo-electric control means,'responslve to a certain lateral movement of the web and disposed at each side of the web beyond the edges and thus out of contact with the web, adapted to effect repositioning of the web to the desired path of travel, said control means including means responsive to certain operating conditions of the system of control, adapted to restrict the controlling action to the photo-electric control means at one side of the web.

17. In a control system for a machine operating on web material and having a plurality of elements including photo-electric control means disposed adjacent but just beyond each edge of the material, control devices, controlled by the photo-electric control means, adapted to maintain the edges of the material away from the photo-electric control means, said control devices including means, responsive to certain changes in operating characteristics of either one of said-photo-electric 'control means, adapted to control the transverse movement of the web of material so that one edge thereof is maintained adjacent one of said photo-electric control means.

PAUL E. FRJEDEMANN.

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