US2974893A - Apparatus for controlling tension in a running web - Google Patents

Description

March 14, 1961 2,974,893

APPARATUS FOR CONTROLLING TENSION IN A RUNNING WEB c. AARON,

Filed NOV. 19, 1956 njwm,

INVENTOR.' CHARLES AARON am, w om ATTO RN EY United States Patent() APPARATUS FOR CONTROLLING TENSION IN A RUNNING WEB Charles Aaron, West Caldwell, NJ., assignor to Cameron Machine Company, Brooklyn, N.Y., a corporation of New York Filed Nov. 19, 1956, Ser. No. 622,999

2 Claims. (Cl. 24275.43)

This invention relates to improved apparatus by means of which it is possible to control very accurately the tension in a web during running of the latter from one roll to another in processing of the web.

In the running of the web, the tension thereof is commonly imparted by imposing a braking eiect upon a pay-out roll of the web material and the web tension is controlled by either increasing or reducing the braking eiect. According to this invention, the pressure of compressed air which operates a brake, effective upon such a pay-out roll, is continuously subjected to very tine control in response to variations in force applied upon a guide roller by the tension in a web passing over said roller.

A preferred embodiment of the invention and a second of numerous possible variations of the invention are illustrated in the accompanying drawing without, however, limiting the invention to the particular arrangements disclosed in said drawing.

In the drawing:

Fig. 1 is a diagrammatic illustration of a preferred embodiment of this invention, and

Fig. 2 is a view showing a modification of a portion of the apparatus shown in Fig. 1.

Referring to Fig. l, a running web 10, which may be paper, sheet plastic, cloth or other web material being processed, is caused to pass upwardly, onto, over and downwardly with respect to a guide roller 12. The latter, ordinarily, is located between a pay-out roll and a receiving roll, neither of which is shown although in the lower right part of Fig. 1, there is shown a neck or shaft 14 of a pay-out roll having associated therewith two oppositely working brake arms 16, 18, the operation of which controls the paying out of web material from such a related pay-out roll.

The guide roller 12 is rotatably supported at its ends in spherical bearings 20 and 22, the latter being rigidly supported upon a suitable bracket 24, riveted, bolted or otherwise rigidly fixed to a frame member 26 of or adjacent to the machine by which the web is being processed;

, and the bearing 20 is yieldably supported by means which will permit minute vertical movement of the bearing 20 in response to variations in tension of the running web 10.

The support for the 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 30 and co-acting with bracket 32,

permit the mentioned vertical adjustment of the position ice adjustable nut 46, 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) will yieldably support lthe roller 12 in an approximately' horizontal attitude and the diaphragm 38 will be located approximately in the plane of its peripheral attachment to said cylinder.

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 the diaphragm, serves as a hydraulic chamber 52 and is connected, in a manner now to be described, with duid-pressure instrumentalities by means of which the brake arms 16 and 18 are so operated as to vary their braking eiect 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. v

The principal mentioned duid-pressure instrumentalities are substantially similar fluid-pressure responsive pres- 'i sure-regulating valves 54 and 56 (valve 54 being sometimes referred to herein as a tension-sensing valve and valve 56 being sometimes referred to herein as a brake supply valve), a manually adjustable pressure-regulating valve 58 (sometimes referred to herein as a tensionadjusting valve), a cam-actuated pressure-regulating valve 60, oppositely acting cam-actuating pressure cylinders 62 and 64, and a brake-actuating pressure cylinder 66.

The mentioned fluid-pressure instrumentalities are inter-connected by suitable piping, as shown in Fig. 1, between the tension-sensing cylinder 28 and the brake arms 16, 18. Also connected in the piping, where shown, are a check valve 68 permitting free flow of liquid from valve 54 toward cylinder 28, an adjustable throttle valve 70 controlling flow of liquid from cylinder 28 toward valve 54, and a pressure gauge 72.

Connected between piston rods 74, 76 of diaphragms 78, 80 of the cylinders 62, 64 is a mounting piece 82 upon which is pivoted a cam member 84 the angularity of which is adjustable by means of an adjusting screw 86 to permit the establishment of a desired relationship of the cam members cam surface 88 with reference to a plunger 90 which is operated by said cam member to control the valve 60. A spring 92, compressed between the extremities of brake arms 16 and 18, tends to urge said arms apart to reduce the braking etect on pay-out roll shaft 14 while the pressure cylinder 66 tends to draw sid arms toward each other to increase the braking e ect.

In the described apparatus, la substantially closed or conned body of oil or other suitable liquid completely occupies chamber 52 of the tension-sensing cylinder 28, an upper or hydraulic chamber 94 of valve 54 and the piping and valves connected between said two chambers. All other illustrated piping and pressure chambers are occupied and/ or operated by air which, in a compressed state, enters the piping from a suitable source of supply where indicated by a legend to that effect in the drawing.

The several illustrated pressure-regulating valves, per se, are not the present invention; hence, they have been shown only diagrammatically. They should have characteristics now to be given. Each should have, respectively, line pressure chambers 54LP, 56LP, 58LP and 60LP, co'nnected to the supply of compressed air to receive that air at supply pressure, regulated-pressure chambers 54RP, 56RP, SSRP and 66RP, from which regulated pressure may pass to function as hereinafter described, and suitable internal valve elements, diaphragme and exhaust Patented Mar. 14, 1961v Vapart from the disclosed apparatus.

3 permittngpres'sure regulation in a well understood manner.

In valves 54 and 56, control of pressure regulation is Y,effected by .changes lin fluid pressure in chambers 94 and 496, respectively, ofsaid valves. In valve 58, control-of pressure regulation .is "effected Vby manipulation of `Vpres- ;sure-control Vscrew -98 and intvalve 60, controlof pres- 4:sureregulation. isV elected by longitudinal movement of lplunser 1 Y l broadly considered,'maintenance of a desired tension inthe running web depends upon counter-acting `pressures,introduced into cylinders 62 .and 64 vthrough `valves 54`and 58. Variations in such counter-acting pressures govern the movement off the plunger 9G and kthereby V causevalves 56 `and 60 to control the brake arms 16 and i18 Yand thereby'control the web tension. Thus, it is im- 'Aportant to consider-thel means by which such counterlacting pressures are continuously controlled and; if necessary, varied to achieve correction of variations in -the web tension. Y Suchcounter-acting pressures Yare controlled, on the Vone hand, by movement ofrliquid Vor shifting (of liquid pressure into and from chamber 94 of valve 54 as diaphragm 38 of cylinder 28 rises and falls minutely with .variations in the downward force imposed upon roller 12 .by variations in the tension of the running web it). The

.increase'of the liquid Volume or pressure in chamber 294 increases the` air pressure against diaphragm 78 and Vlettwardly. On the other hand, screw98 of valve 58 constitutes manual means Vfor similarly controlling Aair :pressure in cylinder 64 to control movement of the cam 841leftwardly. v

Y From experience, it maybe ascertained'tha by manual adjustment of-screw98 to establish a given air pressure Aagainst diaphragm 80 (indicated on gauge 72), the differential between that pressure and the pressure applied l.oppositely against diaphragm 78 under the control of diaphragm'SS'wilL'if unvaried, hold the cam'84 in such l-position as to cause valves vStaud 6@ to keep steady the braking elect of brake armsY 16^and 18 and thereby maintainthe desired Web tension. It is important, however, to :provide for lpractically instantaneous compensation for web tension changes that occur from conditions arising The disclosed apparatus accomplishes such compensation.

Thus, let it be supposed that the web 10 is running and that screw 98' has been set to yield the desired web tension, and that'an'undesired increase or decrease or alternate increases and decreases occur in the web tension. tlf :the'variation is a tension increase, the resultant increased downward force upon roller 12 causes diaphragm 38 to rrlove minutely downwardly, thereby forcing additional liquid to move into chamber 94. This causes valve S4 to establish an increased pressure in chamber 54RP and against diaphragm78, thereby shifting cam 84 rightward- Yly to permit plunger 9i) to rise to decrease the air pressure-in chamber 60RP of'valve 6i) and chamber 96 of valve S6. The decreased pressure in chamber 96 causes a decrease of 'the air pressure in chamber 56RP of valve 56 and in brake cylinder 66, thereby enabling spring 92 'to reduce the braking effect of brake arms 16 and 18 to -provide compensatory reduction in the tension of the Arunning web.

In the event of an undesired decrease in the web tenvfsion, the diaphragm 3'8 will rise, thereby causing operations opposite tothose just described with reference to rundesired tension increases. The described apparatus is very'eiective for giving quick compensation by minute rising and/or falling of the diaphragm 38 with conse- 'quent tension-controlling voperations as just described.

The modification of Fig. 2 is an arrangement in which the tension-adjusting valve 5S may be located at a considerable distance from the other disclosed apparatus if desired, When that is Adesired, -the regulated pressure, in chamber SRP, instead of being applied directly to dia- -pl'iragn StL-'as infFi'g. 1, tis communicated to apressurecontrol chamber 10i) of'a pressure-regulating valve 162 which maybe similar to valves 54 and 56. The valve v102 yhas aline pressure-chamber 1021,13 receiving air ranged to control directly the operation of brakecylinder 66, but the inclusion of valve`56 usually yields more satisfactory results, y K

It will readilybe perceived that the inventive concept may -be utilized in various other Ways Without, however, departing from the invention as set'forth in the following claims.

I claim:

l. In running-web, tension-controlling apparatus having an elongate guidemember against which a running web'presses when theweb isnnder tension and which guide member is-movable in response to variations inthe pressure'of the Web thereagainst, ya uid-pressure-operated brake mechanism adapted to vary' the tension in a running web, and a Huid-pressure circuit adapted to supply uid under pressure to said brake mechanism to control the operation of the latter; means for controllingthe duid pressure in said circuit, comprising mounting means, pivotally supporting one endof said guide member, a iluidpressure cylinder having a diaphragm` therein, a stem con- Ynected between the other end of said guide member and said diaphragm to actuate the latter in response to lmovement of the guide members said other end, a fluid-pressure-responsive control valve connected in controlling relation to said circuit, and a substantially closed body of lReferences Cited in the tile of this patent vUNITED STATES PATENTS y 954,089 f Goss Apr. 5, 1910 1,652,299 Carpenter Dec. V13, 1927 2,291,033 VGoepfrich July 28,1942 2,472,548 Schnell June 7, 1949 2,661,773 Kretzschmar Dec. S, A1953 2,667,887 Holacker Feb. .2, 1954 FOREIGN PATENTS 607,790 Great-Britain i sept. e, i948

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