US2974894A - Apparatus for counteracting tension variations localized toward either side of a running web - Google Patents

Description

C. AARON March 14, 1961 APPARATUS FOR COUNTERACTING TENSION VARIATION LOCALIZED TOWARD EITHER SIDE OF A RUNNING WEB Filed June 12, 1958 United States Patent APPARATUS FOR COUNTERACTING TENSION VARIATIONS LOCALIZED TOWARD EITHER SIDE OF A RUNNING WEB Charles Aaron, West Caldwell, N.J., assignor to Cameron @Iachine Company, Dover, N.J., a corporation of New ork Filed June 12, 1958, Ser. No. 741,537

This invention relates to improved apparatus by means of which it is possible to control efiectively the tension in a web during running of the latter from one roll to another in processing of the web. It relates more particularly to such control even where tension variations predominate toward one side of the web and irrespective of which side of the web might have such variations. The present invention is an improvement over the invention disclosed in my copending application Serial No. 622,999, filed November 19, 1956.

The invention disclosed in my said copending application is well adapted for the control of tension in a running web where the tension therein is substantially similar toward both sides of the web. Sometimes, however, the tension in a web being run through a winding machine might be substantially localized toward one side of the web, in which situation the invention of said copending application would be quite eiiective if the tension were predominant toward one side of the web, but considerably less effective if the tension were predominant toward the other side of the web. It is desirable, of course, that winding machines have tension-control means which are similarly responsive to tension variations in the web even though such variations are predominant at one side or the other of the web.

Accordingly, an important object of the present in vention is the provision of improved web-tensioning means which are responsive to tension variations at-either or both sides of a running web.

The foregoing and other more or less obvious objects are accomplished by the present invention wherein a guide roller, which is directly subject to the tension of the running web, is hydraulically supported or backed-up at both its ends, the supporting or backing liquid at opposite ends of said guide roller being independently sensitive to tension variations imposed by the running web toward the ends of said roller. The bodies of liquid supporting or backing the two ends of said guide roller are so contained and utilized in a hydraulic control system that if tension variations in the web tension toward either or both ends of said guide roller are accompanied by a departure from the desired general web tension, said bodies of liquid function to control a brake which exerts a suitable braking elfect upon a pay-out roll of a webwinding machine in order to effect compensation for such web-tension variations and to restore a desired general tension condition in the running Web.

A preferred embodiment of the present invention is illustrated diagrammatically in the accompanying drawing without, however, limiting the invention to the particular mentioned embodiment.

In the drawing, the running web 10, which maybe paper, sheet plastic, cloth, metal or other web material being processed, is shown as passing upwardly, onto, over and downwardly with respect to a guide roller 12. The latter ordinarily is located between pay-out and receiving rolls of a winding machine, neither of which rolls is shown-although in'the lower right part of the drawing there is shown a neck or shaft 14 of a pay-out roll having associated therewith two oppositely working brake arms 16, 18 which control the pay-out roll and, hence, the paying-out of web material therefrom.

The guide roller 12 is rotatably supported, at its op posite ends, in similar spherical bearings 20, 20a which are yieldably supported by means which permit minute vertical movement or vibration of said hearings in response to variations in tension of the running web 10. If the tension variations occur quite uniformly across the entire web, then both said bearings, at opposite ends of the roller 12, yield minutely and quite similarly. On the other hand, a tension increase which is localized or most effective toward one side of the web would cause the corresponding end of the roller 12 to descend minutely while the other end of said roller either would descend to a lesser degree or even rise minutely as a result of the relatively lower tension at the corresponding side of the web. Thus, if tension variations occur non-uniformly at opposite sides of the Web, both ends of the roller would undergo minute movements to restore the desired general tension in the web in a manner hereinafter ex} plained.

As certain parts cooperating with bearings 20 and 20a are identical and function similarly, said parts cooperating with bearing 26a are given reference characters in the drawing differing from those used for similar parts coopcrating with bearing 20 only in the addition of the letter a. Also, the following description or" parts cooperating with hearing 20 may be understood as descriptive of similar parts cooperating with bearing 29a and having reference characters including a in the drawing.

The support for bearing 20 comprises a pressure cylinder 28 (sometimes referred to herein as a tension-sensing cylinder), having a mounting stud 30 by means of which the cylinder 28 is supported for vertical adjustment upon a bracket 32 which is suitably fixed to a machine-frame member 34. A pair of adjustment nuts 36, threaded on the stud 3t) and coacting with bracket 32, permit the mentioned vertical adjustment of the position of the cylinder 28.

Within the cylinder 23 is a diaphragm 38 from the center of which a stem 40 extends upwardly and slidably through and to the exterior of a guide portion 42 of the top wall of said cylinder. Upon the upper end of said stem is threaded a spring-seat element 44, and between the latter and an adjustable nut 45 threaded on said guide portion, is disposed a compression coil spring 48.

The bearing 20 rests upon the spring-seat element 44, and the adjusted positions of nut 46 and of cylinder 28 are such that the spring 48 and liquid in the cylinder 28 and in a tension-sensing valve (hereinafter described) yieldably support the adjacent end of the roller 12 with the diaphragm 38 located approximately in the plane of its peripheral attachment to said cylinder. With the bearings 20, 20a similarly supported, the roller 12 is held in an approximately horizontal attitude so that tension varia tions which are uniform across the entire width of the web are sensed uniformly at both ends of the roller 12 while a tension variation which is localized toward one side of the web will be nonuniformly sensed at the bearings 26 and 20a.

The interior of the cylinder 28 above the diaphragm 38 is suitably vented as, for example, by a port 50. The area Within cylinder 28 below said diaphragm serves as a hydraulic chamber 52 and is connected, in a manner now to be described, with other fluid-pressure instrumentalities by means of which the brake arms 16 and 18 are so operated as to vary their braking effect upon shaft 14 and thereby control continuously the tension in a web being drawn from a roll carried by said shaft and constrained to rotate only as permitted by said shafts rotation.

Patented Mar. 14, 1961 The principal mentioned other fluid-pressure instrumentalities which are responsive to vertical movement or vibration of the bearing are a fiuid-pressure-responsive pressure-regulating valve 54, sometimes referred to herein as a tension-sensing valve, and a cam-actuating pressure cylinder 62. Parts similar to those cooperating with bearing 20 as hereinbefore mentioned but cooperating similarly .with bearing 20a are numbered in the drawing as 28a, 30a, 32a, 34a, 36a, 38a, 40a, 42a, 44a, 46a, 48a, 50a,.52a, 54a, and 62a. Additional fluid-pressure instrumentalities which cooperate with those already mentioned are a cam-actuating pressure cylinder 64 acting in opposition to cylinders 62, 62a, a brake-actuating pressure cylinder 66, a pressure-responsive, pressure-regulating valve 56, controlling fluid pressure directed into cylinder 66, a tension-adjusting, pressure-regulating valve 58, and a pressure-regulating pilot valve 60 which controls the operation of valve 56.

The mentioned fluid-pressure instrumentalities are interconnected by suitable piping, as shown in the drawing, between the tension-sensing cylinders 28, 28a and the brake arms 16, 18. A piston rod 68, provided with suitable packings (not shown), extends slidably into cylinder 62 and through cylinder 62a and is fluid-tightly fixed to diaphragms 70, 72 in said cylinders, respectively. Another suitably packed piston rod 74 extends slidably into cylinder '64 and is fixed to diaphragm 76 in the latter cylinder. Connected between the free ends of piston rods 68 and 74 is a mounting piece 78 upon which is pivoted a cam member 80, the angularity of which is adjustable by means of an adjusting screw 82 to permit the establishment of a desired relationship of the cam members cam surface 84 with reference to a plunger 86 which is operated by said cam member to control the valve 60. A spring 88, between the extremities of brake arms 16 and 18, tends to urge said arms apart to reduce the braking effect on pay-out roll shaft 14 while fluid pressure in cylinder 66 tends to draw said arms toward each other to increase the braking effect.

Pressure cylinder 28 is connected, as shown, to valve 54 by piping in which are disposed an adjustable throttle valve 90 controlling flow of liquid from cylinder 28 to- 7 having a vent port 102 freely communicating with ambient atmosphere. 'A non-apertured disk 104, constituting a central part of the diaphragm 100, is rigidly interconnected with a centrally apertured valving disk 106 of a diaphragm 108 by separated spacers 110 which permit fluid to pass from chamber 54RP to chamber 54V and thence to atmosphere through port 102. The diaphragm 108, spaced from diaphragm 100, forms chamber 54V therebetween.

A valve element having a lower seat portion 112, yieldably seated in a valve port 114 by a compressed spring 116, controls flow of compressed air to chamber 54RP and thence to cylinder 62. The seat portion 112 has a rigid, integral, upstanding, second seat portion 118, the upper end of which seats in the aperture of disk 106 and, through upward flexing of the diaphragms, controls exhaustion of fluid from cylinder 62 and chamber 54RP through chamber 54V and port 102.

Even slight movement of liquid from chamber 54CP through check valve 92 to chamber 52 (or, i.e., a pressure reduction in chamber 54C?) lifts disk 106 sufliciently to cause the latters aperture to be disengaged by the seat portion 118 to exhaust fluid from cylinder 62. However, if the direction of such slight liquid movement is reversed, diaphragms 100 and 108 are urged downwardly, thereby unseating seat portion 112 from valve port 114, enabling line pressure from chamber 54LP to increase fluid pressure in cylinder 62.

Valve 60 differs from valve 54 chiefly in that the latters upper diaphragm 100 and control pressure chamber 54CP are omitted. In valve 60, diaphragm 120, apertured disk 122, valveseat portions 124 and 126 and spring 128 are substantially similar to and operate similarly to corresponding parts already described with reference to valve 54. A chamber 60V, above the diaphragm 120, serves as a vent chamber for venting the uppermost chamber of valve 56. The plunger 86, by moving upwardly or downwardly, serves, through compressed spring 130, to operate the valve seat portions 124, 126 in the same manner as ward valve 54, and a check valve 92 permitting free flow of liquid from valve 54 toward cylinder 28. Similarly, the pressure cylinder 28a is connected by piping to valve 54a and in said piping are located an adjustable throttle valve 90a and a check valve 92a. Connected between tension-adjusting valve 58 and the cam-actuating pressure cylinder 64 is a pressure gauge 94.

The several illustrated pressure-regulating valves 54, 54a, 56, 58 and 60 per se are not the present invention; hence, they have been shown only diagrammatically. iressure-regulating valves for use in practicing this invention should have such characteristics as enable them to function as hereinafter explained. Although reference to my mentioned copending application should suflice to provide details of said valves, the following description thereof should afford an independent understanding of them.

Valves 54, 54a and 56 are similarly controlled or operated by fluid pressure and are shown diagrammatically as being alike in structure; therefore, a description of valve 54 should serve, also, with respect tovalves 54d and 56.

Valve 54 has, within and formed by its casing walls, a line pressure chamber 54L? connected to the legend-indicated supply of compressed air toreceive that air at sup: ply pressure, a regulated-pressure chamber 54RP, from which regulated pressure may pass to cylinder 62 tofunction as hereinafter described, and a control pressure chamber 54C'P which, through throttle valve 90 and check valve 92, is in liquid communication with chamber 52 in cylinder 28. I v

The chamber 54CP is fluid-tightly separated from a vent chamber 54V by a diaphragm 100, the latter chamber the pressure-induced upward and downward flexing of diaphragm 108 in valve 54 operates the valve seat portions in the latter valve.

Valve 58 differs from valve 60 only in that the screw, to the upper end of which the handwheel 96 is rigidly fixed, is turned to be raised or lowered to control the valve while the plunger 86 of valve 60 is operated by the cam member 80.

It is reiterated that, while the valves 54, 54a, 56, 58 and 60 are described herein with reference to the diagrammatic illustrations thereof in the accompanying drawing, valves of different structural design may be employed; the test as to the adaptability of valves for use in practicing this invention being that they operate in the manner herein described.

Fluid pressure to which valves 54, 54a and 56 are responsive is introduced into the chambers thereof which are shown as the uppermost chambers of said valves in the drawing. An increase in pressure in such an uppermost chamber of any of said valves conditions the valve to deliver an increased pressure of fluid through its lower chambers while a decrease in pressure in such an uppermost chamber conditions the valve to deliver decreased pressure of fluidthrough its lower chambers. In valve 58, handwheel 96 is manually screwed down to increase the fluid pressure delivered through the valve while, in valve 60 the plunger 86 is pushed down by cam to increase the fluid pressure delivered through the valve. Opposite turning of the handwheel 96 and upward movement of plunger 86 operates to decrease the fluid pressure delivered through valves 58 and 60.

In the describedv apparatus, a substantially closed or confined body of oil, or other suitable liquid, completely occupies chamber 52 of the tension-sensing cylinder 28, the upper hydraulic chamber of valve 54 and the piping and valves connected between saidtwo chambers. Sim:

ilarly, a separate, substantially closed or confined body of oil, or other'suitable liquid, completely occupies chamber 52a of the tension-sensing cylinder 280, the upper chamber of valve 54a and the piping and valves connected between said two chambers.

which, in a compressed state, enters the piping from a suitable source of supply indicated by a legend to that effect in the drawing.

Maintenance of desired tension in running web depends upon the pressures introduced into cylinders 62, 62a through valves 54, 54a inopposition to pressure introduced into cylinder 64 through valve 58. Variations in such opposing or counteracting pressures govern the movementof the plunger 86 by cam 80 and thereby. cause valves 56 and 60 to control the brake arms 16 and 18 and thereby control the web tension. In operation, one operating a winding machine which includes the subject apparatus turns handwheel 96 of valve 58 to a-point which will cause said valve to deliver to cylinder 64 at such pressure (indicated on gauge 94) as will-cause -the web, to -be wound through said machine from a roll, to be maintained at a desired tension. Experience enables the operator to know the approximate proper setting for said handwheel.

If tension is substantially uniform across the web, rather than localized toward one side thereof, the web tension applied upon roller 12 would somewhat depress both diaphragms 38 and 38a approximately equally, thereby establishing quite similar hydraulic pressures in the upper chambers of valves 54 and 54a, causing the latter to pass compressed air, at about equal pressures, into cylinders 62 and 62a. The pressure in both last-mentioned cylinders operates cumulatively upon piston rod 68, in opposition to piston rod 74 (operated by the adjusted pressure in cylinder 64), and, in the event of general tension variations during winding, causes cam 80 to operate valve 60. The latter operates in such manner as to cause valve 56 .to deliver air to brake cylinder 66 at such pressure as to operate the brake on a related payout roll to maintain the desired tension in the running web.

A web-tension variation which might be similar or equal toward both sides of the running web would be sensed equally by both of cylinders 28 and 28a, thereby equally modifying air pressures in cylinders 62 and 62a to operate cam 80 in such manner as to cause the brake mechanism to restore and maintain the desired web tension.

Tension and variations in the tension of a running web, however, are seldom, if ever, equally distributed toward both sides of the web. In winding web from any one roll, the tension is usually effective more toward one side than the other of the web and this predominance of tension may shift back and forth from one side to the other in winding a single roll. If, under such conditions, the roller 12 is yieldably supported hydraulically at only one end, as in the apparatus disclosed in my said copending application, tension variations predominantly effective toward the side of the web which is farthest from said hydraulically supported end are not as strongly sensed nor as readily or effectively corrected as are tension variations predominating toward the hydraulically supported end of the roller 12.

Where such unequal tension variations or shifting tension variations occur in apparatus according to this invention, a tension variation toward one side of the web causes the liquid pressure in chamber 52 or 52a at the corresponding end of roller 12 to increase if the tension variation is an increase or to decrease if the tension variation is a decrease.

As hereinafter explained more fully, an increase in pressure in chamber 52 (when, as ordinarily, no general or overall tension change occurs) is accompanied by a corresponding pressure decrease in chamber 52a, and vice versa.

6 As this invention operates similarly withrespect to tension variations concentrated at either side of the web, let 1t be assumed that after tension, during winding, has

been evenly distributed across the web, a condition occurs All other illustrated pairing 5 (usually in the web maten's!) which causes the tension,

and pressure chambers preferably are occupied by air pressure in chamber 52 and in the uppermost chamber,

54CP, of valve 54 is increased and fluid pressure in chamber 52a and in the uppermost chamber of valve 54a is correspondingly decreased.

The increased pressure in the uppermost chamber of valve 54 forces the diaphragms of that valve downwardly to unseat valve seat portion 112 slightly, thereof permitting compressed air, from the source of supply thereof, to increase the pressure in cylinder 62. The decreased pressure in the uppermost chamber of valve 54a and probably the somewhat decreased compressive force applied to spring 48a cooperate to cause the diaphragms in valve 54a to rise, thereby opening the aperture in the lowermost of said diaphragms to vent air from cylinder 62a to reduce pressure in the latter to the extent that pressure in cylinder 62 has, at the same time, been increased.

In the assumed situation that there has been no change generally in the tension in the web, the total of the increased pressure in cylinder 62 and the decreased pressure in cylinder 62a remains equal to the pressure in cylinder 64 and the action of brake arms 16, 18 remains unchanged, leaving the general web tension unchanged. Thus, in the just-assumed conditions, the roller 12 has tilted slightly, descending slightly at one end and ascending slightly at its other end.

If some momentary or temporary condition occurs during a winding operation and causes the general tension of the web to depart from the predetermined tension, the total pressure in cylinders 62 and 62a will rise as the result of a general tension increase or drop as the result of a general tension decrease. In either situation, the total pressure in cylinders 62 and 62a will, for a time, be out of balance with the pressure in cylinder 64, thereby causing such shifting of cam with rods 68 and 74 as to cause valves 60 and 56 to vary the air pressure to brake cylinder 66 to either decrease or increase the braking effect as necessary to restore the desired predetermined general tension in the web. 7

As web material passes from the braked pay-out roll, the general web tension will gradually increase unless the braking of said roll is eased off. Any such tension increase, however, increases the totals of the pressures in chambers 52 and 52a and consequently increases the totals of the pressures in cylinders 62 and 62a, either equally or unequally, depending upon whether or not the distribution of tension across the web has been uniform; and such total pressure increase in cylinders 62 and 62a, while pressure in cylinder 64 remains unchanged, causes cam 80 to control valve 60, and the latter to control valve 56, to reduce the pressure in brake cylinder 66 to permit spring 88 to ease off the braking efiect. This easing ofi occurs gradually as the winding operation progresses.

Thus it is apparent that this invention provides improved means which, irrespective of whether general web tension is distributed evenly or unevenly across the web, operate effectively to maintain a desired predetermined tension in the web.

It will be understood that the present inventive concept may be utilized in various other ways without, however, departing from the invention as set forth in the following claims.

Iclaim:

1. A running-web, tension-controlling apparatus comprisingan elongate' guidemember against which a'running web presses when the Web is under tension and which guide member is similarly and independently supported movably at its opposite ends to enable. it to move at either of said ends in response to pressure of the web thereagainst, a pay-out roll from which the web passes to said guide member, a fiuid-pressure-operated brake mechanism coacting with said pay-out roll to control the issuance of they wehfrom said roll and thereby vary the tension in the running web, a fluid-pressure circuit adapted to' supply fluid under pressure to said brake mechanism to control the operation of the latter, and means, including a fluidpressure-responsive control valve mechanism in controlling relation to said circuit, for controlling, the fluid pressure in said circuit and brakev mechanism and including, also, separate, similar hydraulic meanscoactingseparately with opposite ends of said guide member for controlling the operation of said control valve mechanism; each of said hydraulic means comprising; a substantially closed body of liquid under pressure applied both against a re- 'lated end of said guide member and, against said control valve mechanism, and adapted therebyto control the operation of said valve mechanism and; said brake mechanism in response to minute movements of said guidemem ber,'at either end thereofQresirl'tingdrom variations in the -web tension. 7

2. Apparatus according to claim 1,:further including, in each of said hydraulic means, a diaphragm against one side of which the pressure of said body of liquid is effective, and said diaphragm having a stem' at its other side in supporting relation to said guide member.

' References Cited in the file of this patent UNITED STATES PATENTS 2,755,032 Justus July17, 1956

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