US 3664561 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
y 23, 1972 B. A. FEIERTAG 3,664,561
WEB GUIDING DEVICE Filed Nov. 26, 1 969 2 Sneets-Sheet 2 //V VE/V TOPS 5190c? ,4. F5-7EQ 724 a United States Patent Office 3,664,561 Patented May 23, 1972 3,664,561 WEB GUIDING DEVICE Bruce A. Feiertag, Oklahoma City, Okla., assignor to Fife Corporation, Oklahoma City, Okla. Filed Nov. 26, 1969, Ser. No. 880,149 Int. Cl. B65h 25/26 US. Cl. 226-21 7 Claims ABSTRACT OF THE DISCLOSURE A device for guiding elongated flexible webs at a catenary or free loop in the web and including a steering roller carried by a framework which rotatably supports the roller for rotation about an axis extending substantially parallel to the plane of the web and in a position to contact the surface of the web. The framework is mounted for pivotation so that the rotational axis of the roller may be extended perpendicularly to the direction of travel of the web, or may be shifted to extend at various selected angles to such direction of travel. The roller is of a width, as measured along its axis of rotation, which is less than the width of the web as measured perpendicularly to its direction of travel. -A suitable actuating device is provided for pivoting the framework inresponse to a sensed departure of the web from a desired course of travel.
BACKGROUND OF THE INVENTION Field of the invention This invention relates to web guiding devices and systems, and more particularly, to such systems which include a steering roller for guiding a web of greater transverse width than the width of such steering roller.
Brief description of the prior art It is often necessary to maintain a desired alignment of elongated, substantially monoplanar webs or strips of flexible material as such material is moved from one location to another, such as by unwinding it from a source roller and winding it upon a take-up roller. One method which has been utilized in the past for accomplishing such alignment is the use of guide rollers which contact the web across the width of the web and which are shifted to various positions with respect to the direction of travel of the web in order to counteract or overcome movements of the web from an aligned status to a misaligned status. Various types of shifting movements have been imparted to such guiding rollers to achieve the desired corrective action, and examples of several such guidance systems are those which are described in US. Pats. 2,797,091, 3,098,595, 3,326,435, and 3,431,425 assigned to the assignee of the present application. In general, guide roller systems will include one or more guide rollers, a sensing device for sensing transverse shifts of the web as it commences to become misaligned, and an actuating mechanism which is connected between the sensing device and the guide roller for responding to signals indicating misalignment as developed by the sensing device, and converting these signals to a corrective movement by the guide roller.
One type of guide roller utilized in web guiding is termed a center pivoted roller, and the action of this roller in guiding the web may be contrasted with rollers which guide, at least in part, by effecting a bodily shift of the roller in a direction which is generally transverse to the web. The latter type of roller will be hereinafter referred to as a shifting roller in contrast to center pivoted guide rollers, or others in which the instant center has a fixed location in a plane containing the axis of rotation of the roller and extending normal to the direction of travel of the web. These shall be referred to as an angling rollers. Their guiding function is accomplished by angling the rollers so that a frictional impetus is provided to move the web toward the desired original position from which it departed.
In one respect, guidance systems which include angling rollers of the type described tend generally to be more unstable than the shifting rollers, because where angling rollers are used with fixed sensing heads, there is a phase lag between the sensed departure of the web from the desired path of travel and the response of the web to the resulting corrective positioning of the angling roller required to ultimately return the web to its original desired course of travel. In other words, the sensing head operates by seeing the actual position of the web, and by developing its signal to the device controlling movement of the guide roller on the basis of this seen position. Where the corrective force is developed only by angling the roller with respect to the web, as contrasted with bodily displacement of both web and roller, the cfixed sensing head will continue to send a corrective signal to the angling roller even after the roller has been angled sufliciently that the web will ultimately respond by being steered across the roller to its original, aligned position. The result of the out-of-phase relationship between the sensing of the error and the development of a sulficient corrective movement of the web is the occurrence of hunting or instability, with the error being repeatedly overcorrected, and the web wandering between positions on opposite sides of the desired course of travel. As contrasted with this inherent relative instability (which can be, to some extent, compensated or corrected by the use of certain procedures) guidance systems which utilize angling rollers offer certain advantages over shifting roller systems. Thus, angling roller systems are generally more compact, less complicated in their actuation systems, and can be utilized in some environments where space or web conditions do not permit shifting rollers to be used.
One of the situations of web guiding where shifting rollers cannot be utilized with optimum effectiveness is in the guidance of the exit leg or span of a festoon, loop or catenary which is developed in webs or strips upstream from certain operations being performed on the web or strip. An example of this type of operation is the processing of elongated webs of steel or metals in which pickling, slitting or other treatments or operations are applied to the web either upstream or downstream from a so-called looping pit in which a downwardly depending loop or catenary is developed for purposes well understood in the art (see U.S. Pats. 2,662,271, 2,338,143, and 3,177,749). In other instances, freely hanging loops or festoons are provided in the line of an elongated web of material, and the lowermost portion of the bight in the Web is then observed photoelectrically in order to provide control signals used to synchronize feed and take-up rollers upstream and downstream from the loop, respectively.
It is often desirable, where loops of the sort described are provided, to guide the web along a pre-selected course of travel as the web comes out of the loop and moves through various downstream rollers to subsequent web treatment locations. Various systems for guiding the web at this point have been proposed and utilized. One of the most widely used where steel strip and other relatively stiff websare involved has been a flange guiding system in which flanges are provided adjacent the opposite side edges of the Web at the upper portion of the downstream or exit leg of the loop. These flanges are interconnected for manualadjustment for the width of material being run. The flanges thus confine the web to its desired path of travel. Obviously, a certain relatively high degree of web stiffness is required for this type of guidance to be effective. Moreover, the flange guiding system is not well adapted for accommodating webs of varying width because, in such event, the flanges must either be spaced outwardly from the side edges of the web in order to accept the widest width encountered, or damage to the web will result due to snagging or fouling of the side edges on the guiding flanges.
The use of shifting type guide rollers in loop guiding is frequently diflicult because of space requirements necessary to accommodate the system and because of the usual requirement of such systems that the web be at least partially wrapped around the roller, a requirement which obviously cannot be met if guiding is to be effected simply by acting upon the free-standing, vertically extending exit leg of the web loop. Moreover, attempts to use conventional angling rollers in loop guiding have not been satisfactory with most types of web. In the usual practice entailing the use of angling rollers, the web is extended between an elongated back-up roller, and a nip roller, both of which extend across, and contact, the entire transverse width of the front and back surfaces of the web. These rollers are then pivoted or angled relative to the direction of travel of the web and in response to a corrective signal received from the sensing head so that a corrective frictional force is applied to the web tending to move it across the rollers in a direction to return it to a desired position of alignment. Where this type of guidance system is used in loop guiding, it has been found that the web undergoes angulation (with respect to its desired source of travel) along with the angling rollers, thus either undesirably swinging to one side the bight at the bottom of the loop, or buckling the web between this bight and the steering rollers, or both.
BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention provides a stabilized web guiding device or system which employs a narrow bodied steering roller of the described angling type for guiding a web along a predetermined course of travel in response to compensated corrective signals developed by a sensing device. Broadly described, the web guiding device of the invention comprises a steering roller which is carried by a framework which supports the steering roller for rotation about an axis which extends substantially parallel to the plane of the web. The roller is also positioned for continuously contacting a surface of the Web. The steering roller has a roller face which is of narrower width than the transverse width of the web, this type of roller sometimes being referred to as a narrow bodied roller. Preferably, the width of the face of the steering roller does not exceed one-half the width of the webwhich it steers.
The framework which carries the steering roller is pivotally mounted so that by pivotally moving the framework, the steering roller is caused to pivot about an axis which passes through the center of the roller and normal to its axis of rotation. Means is provided for pivotally moving the framework.
The system of the invention further includes a sensing device which is spaced from the steering roller and its supporting framework, and is adjacent the path of travel of the web. The sensing device continuously senses the position of the web, and develops a signal which is indicative of the position of the web in relation to a null point corresponding to the position of the web when it is properly aligned. There is then further provided compensating means connected between the steering roller and the sensing head, so that when the steering roller is applying a corrective force to the web for counteracting a sensed misalignment of the web, the sensing head signal will be modulated to avoid overcorrection of the misalignment, and thus to impart stability to the system.
Although the invention as thus broadly described is useful in many web guiding applications, it is particularly useful in guiding webs at a loop or festoon formed therein at the location, and for the purposes, hereinbefore described. Where the web guiding device is employed in this manner, it preferably includes a back-up roller which is located on the opposite side of the web from the steering roller and functions to maintain the web in continuous contact with the steering roller.
An important object of the invention is to provide an improved web guiding device for guiding elongated webs or strips in a preselected path of travel by the use of one or more narrow bodied steering rollers in contact with the web and without direct, physical contact with the edge of the material.
Another object of the invention is to provide a web guiding system of good stability in which a device used for sensing misalignment of a web being guided is also continuously apprised of the corrective action taken by one or more steering rollers in response to such sensed misalignment.
A further object of the invention is to provide a web guiding device which can be effectively utilized for guiding an elongated, flexible web as it passes through a free-swinging festoon or loop formed in the web.
An additional object of the invention is to providea web guiding device which can be employed to maintain the alignment of an elongated, flexible web as such web passes through a catenary configuration, the device being capable of maintaining such alignment without buckling the web, and without laterally displacing the bight located at the bottom of the caternary.
Another object of the invention is to provide a Web guiding device which can be relatively economically constructed and maintained, and which is characterized in having a long and trouble-free operating life.
Additional objects and advantages will become apparent as the following detailed description of the invention is read in conjunction with the accompanying drawings which illustrate the invention.
BRIEF DESCRIPTION THE DRAWINGS FIG. 1 is a perspective, partially diagrammatic illustration of one embodiment of the web guiding device of the invention as it appears when used for guiding a web at a catenary therein.
FIG. 2 is a view similar to FIG. 1, but showing a modified embodiment of the invention.
FIG. 3 is a front elevation view of a web guiding device constructed in accordance with the invention.
FIG. 4 is a side elevation view of the web guiding device shown in FIG. 3.
FIG. 5 is a sectional view taken along line 5-5 of FIG. 4.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Referring initially to FIG. 1 of the drawings, an elongated web or strip of flexible material which is to be guided by the web guiding device of the present invention is indicated by reference numeral 10. It will be noted that the web 10 has an entering span 10a and exiting span 10b and a catenary between theentering and exiting spans. The catenary a is formed by passage of the web over a plurality of feed basket rollers 12 and follower basket rollers 14.
For the purpose of maintaining the alignment of the web 10 so that it retains a desired course of travel after leaving the rollers 14, a center pivoted web guiding device constructed in accordance with the present invention is employed, and is designated generally by reference numeral 16. The web guiding device 16 includes, as a critical element therein, a steering roller 18 which is rotatably journaled between a pair of bracket arms 20. The bracket arms 20 extend from a framework 22 which includes a front cross member 24 and a pair of side members 26. The side members 26 are secured to a back plate 28 which is mounted in any suitable way for pivotation about a pivotal axis extended normal to the rotational axis of the roller 18, and through the center of the roller. The back plate 28 has a pair of roller supporting brackets 30 projecting forwardly therefrom and journaling a shaft upon which a back-up roller 32 is mounted. The back-up roller 32 will be observed to cooperate with the guide roller 18 in gripping therebetween a portion of the catenary 100 of the web 10 immediately prior to the point of which the web contacts the basket rollers 14. Projecting from the back plate 28 in the opposite direction from the direction of projection of the side members 26 is a reaction plate 34 which is pivotally connected to the outer end of a piston rod 36 which extends from a cylinder 38.
Extending downwardly from one of the side members 26 is a sensing head supporting arm 40. At its lower end, the sensing head supporting arm 40 carries a sensing head 42. The sensing head 42 is positioned immediately adjacent one of the side edges of the web 10 so that, in a manner well understood in the art, the sensing head may detect any change in the location of the side edge of the web, and thus sense any shifting of the web from a predetermined location.
The sensing hear 42 may be ony of the types currently used for web guiding purposes, such as photoelectric or pneumatic sensors. The sensing head 42 develops a signal at such time as it senses a shifting or movement of the side edge of the web 10 over which it is located. This signal will be indicative of whether the web has departed from the desired path of travel to the right or to the left, and will further be correlated to the magnitude of such departure. The signal developed by the sensing head 42 upon development of misalignment in the web 10 is passed to a suitable controller 43 which, in response to the signal from the sensing head, directs pneumatic or hydraulic fluid to the cylinder 38 for the purpose of actuating the cylinder to initiate a corrective movement of the framework 22. As the piston rod 36 is extended or retracted, the framework 22 is pivoted about its pivotal axis which extends through substantially the center of the web 10, and substantially normal to the surface thereof, so that the framework is angled with respect to the direction of travel of the Web. In other words, in the neutral position as illustrated, the framework 22, and particularly the cross member 24, may be thought of as extending substantially perpendicular to the course or path of travel of the web 10, and corrective signals developed by the sensing head 42 result in the piston rod 36 being extended or retracted to change the angle made by the framework with respect to the direction of travel of the web. Pivotation of the framework 22 causes the steering roller 18 to also be pivoted so that its axis of rotation extends at an angle other than 90 with respect to the path of travel of the web 10. Considered in another way, a tangent to the peripheral surface or face of the steering roller 18 is caused to become misaligned with the path of travel of the web 10. The effect of this angulation of the steering roller 18 with respect to the web 10 will be hereinafter discussed in greater detail.
It will be noted that, as the framework 22 is caused to pivot in the manner described in order to counteract the sensed misalignment of the web 10, the sensing head 42 is also caused to move from its original position either outwardly or inwardly with respect to the original position of the web 10. The manner in which the framework 22 is pivoted is such that the sensing head will always follow the adjacent edge of the web 10. This movement of the sensing head 42 upon the occurrence of undesirable misaligning lateral movements of the web 10 is an important feature of the present invention since, as will be hereinafter explained, it prevents the guidance system from becoming unstable or hunting due to a phase lag between the detection and signaling of shifting of the web from the desired alignment, and the development and application of the corrective pivotal action of the steering roller 18.
FIG. 2 is a modified embodiment of the invention in which the described instability of the guidance system due to excessive phase lag is electronically rather than mechanically eliminated, and by reason of such construction, there is no necessity for mechanically interconnecting the sensing head to the guide roller-carrying framework 22 for concurrent movement therewith. Since the guidance system depicted in FIG. 2 contains a number of the same structural elements as have been illustrated and described in referring to FIG. 1, identical reference numerals have been utilized to identify identical parts where they appear in both drawings. It will be noted in referring to FIG. 2 that a sensing head 44 is here provided which is not mechanically connected to the framework 22, but rather is mounted independently thereof and is stationarily supported adjacent one lateral edge of the web 10 at such time as the web is aligned and is following the desired course of travel. The sensing head 44 in this embodiment of the invention is substantially permanently mounted and thus does not follow the web 10 if the web tends to move out of its aligned status.
The signal developed by the sensing head 44 and indicating departure from the desired alignment by the web 10 is passed to a suitable signal mixing device 46. This device, which may be electronic or an electrical circuitry of a variety of types well known in the art, receives the signal from the sensing head 44 and mixes or combines this signal with a second signal which is generated by the pivoting movement of the framework 22. Any suitable type of transducer 47 for converting the mechanical movement of the framework 22 to an electrical signal suitable for mixing with the signal from the sensing head 44 may be utilized. In effect, the mixer 46 receives a feedback signal from the framework 22 as this framework is pivoted, and combines this signal with the misalignment signal derived from the sensing head 44 to develop the control signal which is passed to the controller 43. The controller 43 then converts the electrical signal received from the mixer 46 to a mechanical signal which controls valving delivering hydraulic or pneumatic fluid to the cylinder 38. The cylinder 38 and piston rod 36 function in the manner hereinbefore described to cause the framework 22 to undergo the necessary corrective movement in order to pivot the steering roller 18 on the web 10.
OPERATION The web guiding systems depicted in FIGS. 1 and 2 operate similarly to each other in guiding the web 10 at a catenary or loop formed therein. We have determined that steering of the web to one side or the other (in a lateral or transverse sense) can be effectively accomplished by pivoting the steering roller about an axis which extends through the center of the roller and normal to its rotational axis. This effectively causes a line tangent to the face of the roller and lying in the plane of the surface of the web 10 which the steering roller contacts to extend at an angle with respect to the webs line of travel (or central longitudinal axis of the web). By pivoting the framework 22 and the steering roller 18 carried thereby in a counterclockwise direction as they are viewed in FIGS. 1 and 2, the web 10 has a transverse component of force applied thereto which tends to move the web toward the left. An oppositely acting force is applied to the web when the roller 18 is pivoted in a clockwise direction. Where a is the angle made by the line tangent to the face of the .roller with the webs line of travel, the rate at which the Web is caused to undergo a transverse movement is proportional to the product of this angle a and the line speed of the web. In other words, the faster the web is being moved through the loop or caternary, the more rapid will be the corrective lateral movement effected by angling the steering roller by a given amount with respect to the course of forward travel of the web.
Guidance of a moving web by narrow bodied steering rollers similar to the steering roller 18 is broadly described in US. Pat. 2,340,242. In the system there depicted and described, however, a plurality of steering rollers are shown and collectively cover the entire transverse width of the web. The web is a cloth fabric, and the steering rollers contact the web at an intermediate portion of a tensioned span extending horizontally between two rollers mounted for rotation about horizontal axes. A switch arm is used as a device for sensing the position of the web and developing a signal which causes concurrent pivotation of all of the steering rollers to counteract misalignment. The control system is a simple on-olf system, however, and the steering rollers remain angled at least until the web moves back to the aligned position. Web momentum and time lags between switch arm actuation, roller actuation and response of the web necessarily result in some instability in the control system which will cause some oscillation or hunting.
The web guiding system of this invention as depicted in FIGS. 1 and 2 is especially well adapted for guiding an elongated, flexible web at the location of a loop or catenary formed therein, although the system is not limited to such applications. In such guiding, one or more narrow bodied rollers may be employed, but the rollers preferably do not extend completely across the transverse width of the web. Due to the fact that the steering rollers bear against a free standing, vertically extending leg of the loop or caternary, it is very desirable to employ a back-up roller, and care must be exercised that the frictional engagement of the steering rollers and back-up roller with the web not be so great that the web is twisted to swing the bight of the caternary to one side, or that the web is buckled or wrinkled.
The web guiding system of the invention is a stable system due to the introduction of compensating feedback to the sensing head and the signal developed thereby. As has been previously mentioned, the sensing head 42 as shown in FIG. 1 continuously sees the edge of the web 10, and develops a signal at such time as the web edge departs from the desired position of alignment and travel of the web. The web 10 may, of course, become misaligned by moving either to the right and toward the sensing head 42, or to the left and away from the sensing head. The sensing head 42 will develop a signal indicative of the direction of movement of the web, and correlated to the magnitude at any instant in time of the dis tance which the web has moved from the null position of the sensing head, which may be defined as the point of registry of the web edge with the sensing head at which the sensing head does not develop any signal indicating misalignment. The misalignment signal is directed to the controller 43, which effectively acts as a transducer converting this signal to power fluid input to one end or the other of the hydraulic cylinder 38. This results in extension or retraction of the piston rod 36 at a rate which is directly proportional to the magnitude at a particular instant in time of the distance which the web has moved from the sensing head null position.
With the extension or retraction of the piston rod 36, the framework 22 is caused to pivot so as to pivot the steering roller 18 in the manner hereinbefore described. The roller 18 is thus pivoted at a rate proportional to the magnitude at any instant in time of the distance which separates the null position of the sensing head 42 and the edge of the web, and the rate of change of the angle a is also proportional thereto. At some value of oz, the rate of lateral steering developed by the steering roller 18 tending to return the web to the desired aligned position Wil exactly counteract the runout rate which produced the misalignment of the web and an equilibrium condition will be reached in which the web does not travel further from the desired position. If, at this time, the sensing head 42 were stationarily mounted in relation to the web, a relatively large distance would separate the edge of the web from the sensing head null position, and the piston rod 36 would continue to extend or retract for a time period, and at a velocity, such that the steering roller 18 would become angled at an angle a substantially greater than that required to counteract the misaligning movement of the web. The web would, of course, then start to return toward the desired aligned position, but for an increment of time At, the sensing head would continue to develop a signal continuing to extend or retract the piston rod 36 as if the web were still moving away from the aligned position. Thus, the steering roller would be further angled on the web up to the time the web regained the desired aligned position, and the effect, of course, would be to drive the web through the desired path of travel and into a position of misalignment on the opposite side of this path. This oscillation of the web back and forth through the desired position of alignment would continue, and this result is said to be a condition of instability in the guidance system.
The present invention employs what may be described as a compensating feedback from the steering roller 18 to the sensing head 42 which markedly stabilizes the sys tem. It will be perceived that the sensing head 42 is rigidly connected to the framework 22 by sensing head supporting arm 40. Thus, when the framework 22 commences to pivot as a result of a signal developed by the sensing head 42 upon drift of the web- 10 away from the aligned position, the sensing head is swung so as to follow the moving web edge. As soon as the angle a creates a rate of corrective steering equivalent to the rate of misaligning movement of the web 10, the distance between the web edge and sensing head null position will become zero and there will be no further piston rod travel, or increase of the angle 0:. The roller 18 will thus continue to pivot until a is increased to'the equilibrium value (as hereinbefore described), thus arresting further movement of the web away from the desired position. At this time, however, the distance of the web edge from the desired lateral position in the machine is relatively small, due to the following action of the sensing head, and such separation as does exist is quickly eliminated due to the steering action of the angled guide roller 18 returning the web toward the desired position. Thus, the overshoot of the steering roller pivotation experienced in an unstabilized system in which the sensing head remains stationary is eliminated.
The compensating feedback to the sensing head 42 ex? perienced with the embodiment of the invention depicted in FIG. 1 may be referred to as mechanical feedback and results from the rigid interconnection of the sensing head 42 to the framework 22. In the embodiment illustrated in FIG. 2, the basic operation of the system is the same as the system shown in FIG. 1 except that compensating feedback is electrically accomplished. Here the sensing head 44 remains fixed relative to, theweb 10, and develops a signal which is proportional in magnitude to the dis:
tance which the web edge moves from the null position.- This signal is passed to the mixer46 where it ismodulated with an output signal from the transducer device 47, which signal is correlated to the pivotal movement of the framework 22; The mixer 46 thus develops a composited signal similar in character and function to the signal developed by the mechanically compensated sensing head 42 used in the FIG. 1 embodiment, and the system is stabilized in like manner.
An actual web guiding device constructed in accordance with the present invention is illustrated in FIGS. 3-5. As here illustrated, the device includes a mounting plate 52 which can be used for mounting the device on any suitable stationary structure 54. The mounting plate 52 has projecting fonwardly therefrom a pair of horizontally spaced beams 56 and 58 which provide support for a pair of side plates 60 and 62 utilized for journaling the shafts of a plurality of basket rollers 64. A transverse supporting bar 66 extends between the forward end portions of the side plates 60 and 62, and has extending downwardly therefrom a framework supporting bracket 68. The framework supporting bracket 68 journals at its lower end, a stub shaft 70 which projects horizontally from a forward transverse frame member 72 forming a part of a framework designated generally by reference numeral 74. The framework 74 includes a rear transverse frame member 76 which is spaced horizontally from the transverse frame member 72 and which is interconnected therewith by a pair of side members 78. The transverse frame member 76 has a stub shaft projecting from a central portion thereof, and the stub shaft 80 is journaled in a suitable bearing block 82 which is secured to, and spaced horizontally from, the mounting plate 52.
It will be seen from the description thus far that the framework 74 is mounted for pivotal movement about an axis extending coaXially through the aligned stub shafts 70 and 80. Journaled between the side members 78 of the framework 74 is an elongated back-up roller 84. It will further be noted that at the end of the left side member 78 (as the apparatus is viewed in FIG. which is secured to the transverse frame member 76, the side member has projecting therefrom a reaction plate 85 which is pivot ally connected to the lower end of the piston rod 86. The piston rod 86 has its other end connected to a piston (not shown) located within a hydraulic cylinder 88. The hy draulic cylinder 88 is pivotally mounted by trunnions in a suitable block 90 to the beam 56.
Extending downwardly from an intermediate portion of the transverse frame member 72 are a pair of horizontally spaced arms 92 and 94. The arms 92 and 94 support at their lower ends a photocell housing 96 which contains a bank of photocells constituting a portion of a sensing device used for sensing the position of a web to be guided by the apparatus. Projecting downwardly from the opposite ends of the transverse frame member 76 are a pair of arms 98 and 100 which support at their lower ends, an elongated lamp housing 102 in which is located a lamp (not shown) functioning to provide illumination for the photocells located in the photocell housing 96 and forming a portion of the sensing means utilized for sensing the position of the web to be guided.
Extending between the arms 92 and 94 at a position intermediate their length is a crossbar 104 which has secured to a central portion thereof a plate 106 carrying roller arm supporting brackets 108 at the opposite ends thereof. The roller arm supporting brackets 108 (see FIG. 5 journal a shaft 110 to which is keyed or secured a pair of roller arms 112. The roller arms 112 also receive intermediate their length a shaft 114 which pivotally engages the outer end of a piston rod 116 extending from a cylinder 118. At their upper ends, the roller arms 112 journal a shaft 120 which has secured thereto :a steering roller 122. It will be noted that the pivotal axis of the framework 74 which is coaxial with the axes of the stub shafts 70 and 80 extends through the center of the steering roller 122 and substantially normal to the rotational axis of this roller about the shaft 120.
Projecting downwardy from the transverse frame member 72 between the arms 92 and 94 are a pair of cylinder supporting brackets 126. The cylinder supporting brackets 126 journal a pair of stub shafts 128 secured to opposite 10 sides of the cylinder 118 so that the cylinder can pivot about the horizontal axis.
In the operation of the web guiding device depicted in FIGS. 3-5, the web to be guided, after being formed in a loop in the manner hereinbefore described, has its exit leg passed upwardly between the steering roller 122 and the back-up roller 84. At this time, the steering roller 122 can be retracted away from the back-up roller 84 by retracting the piston rod 116 into the cylinder 118. The web is then led over the basket rollers 64 to a downstream location at which some further operation is performed on the web which requires it to be maintained in a preselected path of travel. From the previous discussion concerning the present invention, it will be understood that the web is positioned between the steering roller 122 and the back-up roller 84 so that the steering roller bears against the central portion of the web.
When the web is positioned in the manner described, it will pass between the photocell housing 96 and the lamp housing 102. This arrangement of a source of electromagnetic radiation, as provided by the lamps within the lamp housing 102, and a device sensitive to such radiation, such as the photocells provided in the photocell housing 96, constitutes a sensing means by which the position of the web to be guided can be constantly monitored and suitable electrical signals developed to initiate corrective action by the web guiding device. Thus, after the web has commenced its linear travel, should it commence to deviate from the desired course of movement, this deviation will be detected by the sensing means constituted by a the lamp within the lamp housing 102 and the photocells within the photocell housing 96. A signal will be developed indicative of the direction of travel of the web from the null or aligned position and proportional to the magnitude of the distance which the web has moved from this null position. The signal thus developed will be converted to a hydraulic or pneumatic signal which is applied to the cylinder 88 to extend or retract the piston rod 86 as the type of correction required may dictate. Extension or retraction of the piston rod 86 with respect to the cylinder 88 causes the framework 74 to undergo pivotation about the pivotal axis extending through the stub shafts 70 and 80. Thus, as depicted in FIG. 3, the pivoted positions of the framework and those structural elements secured to and moving therewith are depicted in dashed lines, where as the neutral or null position of the framework is shown in full lines.
It will be perceived that upon pivotation of the framework 74 by extension or retraction of the piston rod 86, the sensing means constituted by the lamp and photocells will also be pivoted and will follow the drifting web in the manner hereinbefore described. There is thus incorporated in the system depicted in FIGS. 3-5, a mechanical compensating feedback to the sensing means which permits the system to be stabilized, and hunting or oscillating to be eliminated.
Although certain preferred embodiments of the present invention have been herein described in order to provide an example of the construction and method of practice of the inveniton, it is to be understood that various changes and modifications to the described structures can be effected without departure from the basic principles of the invention and are therefore deemed to be circumscribed by the spirit and scope of the invention as defined by the appended claims or reasonable equivalents thereof.
What is claimed is:
1. A web guiding device comprising:
a narrow-bodied steering roller having a face width less than the transverse width of the web to be guided by contact therewith, said narrow-bodied steering roller having a web contacting peripheral surface with frictional properties such that, upon being turned conjunctively with its axis of rotation, it will slip upon a web being guided, whereby said web will not be creased or wrinkled;
and develop a signal indicative of departure of said web from a preselected position;
a rigid arm mechanically interconnecting said sensing means and said means pivotally supporting the steering roller supporting means for moving the sensing means in the direction of misaligning travel of the Web from said preselected position; and r transducer control means connected between said sensing means and said means pivotally supporting said roller supporting means for pivoting the means pivotally supporting said roller supporting means in response to receipt of modulated signals from said sensing head. 2. A web guiding device as defined in claim 1 wherein said transducer control means comprises a piston and cylinder assembly connected to said means rotatably supporting said steering roller for pivoting said roller supporting means when said piston rod of said piston and cylinde assembly is extended and retracted. 3. In combination, an elongated web of flexible mate rial having opposed, substantially parallel side edges'and having an entering span, an exiting span and a catenary therebetween; and
a device for guiding said web mounted at the upper side of the catenary adjacent the exiting span, said guiding device comprising:
a sensing head positioned adjacent the web for sensing transverse movement of'the-web and developing an output signal indicative'of such transverse movement;
a steering roller positioned between the side edges of the web and having a face contacting a surface of the web between the side edges thereof, said steering roller being mounted for rotation about an axis extending substantially parallel to the surface contacted by the face of the roller, said steering roller having a web contacting peripheral surface with properties such that it will slip upon being turned upon a web being guided, whereby said web will not be creased or wrinkled;
means connected to said roller for pivoting the roller about an axis extending normal to the plane of the surface of the web contacted by the roller face;
a rigid arm connecting said sensing head to said roller pivoting means for swinging said sensing head transversely with respect to said web when said pivoting means pivots said roller to thereby modify the output signal of the sensing head; and
means responsive to said modified output signal for actuating said pivoting means to pivot said roller about its pivotal axis.
4. The combination claimed in claim 3, and further characterized as including a back-up roller on the opposite side of said web from said steering roller and pressing the web against said steering roller.
5. A web guiding device comprising:
a narrow-bodied steering roller having a face width less than the transverse width of a web to be guided by contact therewith;
means rotatably supporting said steering roller for rotation about an axis extending substantially parallel for continuous contact with the surface of the web;
means pivotally supporting said'means rotatably supporting said steering roller for pivotation about an normal to the rotational axis thereof;
5 sensing means spaced from said steering roller and" adapted to sense the position of the web to be guided and develop a signal indicative of departure of said web from a preselected position;
a rigid arm mechanically interconnecting said sensing means and said means pivotally supporting the steering roller supporting means for moving the sensing means in the direction of misaligning travel of the web from said preselected position; and
transducer control means connected between saidsensing means and said means pivotally supporting said roller supporting means for pivoting the formermeans' 6. In combination, an elongated web of flexible material having opposed, substantially parallel side edges, and having an entering span, an exiting span and a catenary therebetween; and 1 a device for guiding said web mounted at the upper guiding device comprisingi a sensing'head positioned "adjacent the web for sensing "transverse movement of the web and developing an output signal indicative of such transverse movement;
of the web and having a face contactinga surface of the web between the side edges thereof, said steering roller being mounted for'rotation about an axis extending substantially parallel'to the surface contacted by the face of the roller;
' means connected to said roller for pivoting the roller about an axis extending normal to the plane of the surface of the web'contacted by the 40 roller face;
'pivotingjmeans for swinging said sensing head transversely with respect to said web when said pivotingmeans pivots said roller and thus modifyingthe output signal of the sensing head response to the pivotal movement of theroller;
sensing transverse movement of the web and developing an output signal indicative of such transverse movement;
a narrow-bodied steering roller positioned between the side edges of the web and having a face contacting a surface of the web between the side edges thereof, said face having a width not exceeding one-half the width of the web which'it,
steers, andsaid steering roller being mounted for rotation about an axis extending substantially said web having, in cooperation, frictional properties such that the face of said steering roller will slip relative to the surface of said web upon said steering roller being turned upon the web side of the catenary adjacent the exiting span, said 7 a steering roller positioned between the side edgesa rigid arm connecting said sensing head to said' said modified output signal parallel to the surface contacted by the face of, the steering roller, said steering roller face andbeing guided, whereby said web will not be creased or wrinkled;
means connected to said steering roller for pivoting said steering roller about an axis extending normal to the plane of the surface of the web contacted by the steering roller face;
means connected between said roller pivoting means and said sensing head for modifying the output signal of the sensing head in response to the pivotal movement of said roller; and
means responsive to said modified output signal for actuating said pivoting means to pivot said steering roller about its pivotal axis.
References Cited UNITED STATES PATENTS RICHARD A. SCHACHER, Primary Examiner