US2983463A

US2983463A - Apparatus for controlling the tension in a running web

Info

Publication number: US2983463A
Application number: US647558A
Authority: US
Inventors: Aaron Charles; Rockstrom Leonard
Original assignee: Cameron Machine Co
Current assignee: Cameron Machine Co
Priority date: 1957-03-21
Filing date: 1957-03-21
Publication date: 1961-05-09
Anticipated expiration: 1978-05-09

Description

May 9, 1961 c. AARON ETAL 2,983,463

APPARATUS FOR coNTRoLLING THE: TENSION IN A RUNNING WEB Filed March 21, 1957 IN VEN TORS CHARLES AA EON BY LEON/IPD CKSTKOM United States Patent i APPARATUS FOR CONTROLLING THE TENSION IN A RUNNING WEB Charles Aaron, West Caldwell, and Leonard Rockstrom,

Madison, NJ., assignors to Cameron Machine Company, Brooklyn, N.Y., a corporation of- New York Filed Mar. 21, 1957, Ser. No. 647,558

4 Claims. (Cl. 2421-7543) This invention relates to a mechanism useful, `with or as a part of a web-winding machine, for maintaining a substantially constant tension in a web which is being run from a pay-out roll to a take-up roll in such a machine to permit processing of the web as itmoves between the two rolls. One of several reasons why such tension-maintenance kis important is the avoidance of web breakage or damage which might occur under excess or non-uniform tension conditions.

An important object of this invention is the provision o f means controlling a condition affecting the web ten# sion, which means are responsive to changes in web tension to cause such controlling means automatically to compensate for such changes.

A condition commonly affecting web tension is the braking effect applied and maintained upon the pay-out roll; and the mentioned object and other more or less specific objects are achieved in a preferred form of this invention by utilizing the torque present at the shaft of a motor which drives the take-up roll to control a brake on the pay-out roll. In such an arrangement an increase in torque at a motor which drives the take-up roll indicates a need for reduced braking effect at the pay-out roll in order to avoid such high tension in the web as to break or damage the latter.

Although the concepts of this invention may be utilized in mechanisms of various designs, nevertheless, it is illustrated in the accompanying drawing as utilized in only one of various possible embodiments without, however, limiting the invention to that particular embodiment.

The drawing is a diagrammatic view of a preferred embodiment of this invention, some portions or components being shown in perspective as viewed from the underside thereof, other portions or components being shown more or less in the form of symbols, and the arrangement of components in the drawing being such as to facilitate an understanding of the invention without regard to the particular location of some of the components in practice and without regard to the particular arrangement of piping that would be employed in an actual installation.

The illustrated apparatus comprises a pay-out roll 10, a take-up roll 12, a pair of driving rollers 14 and 16, guide rollers 18 and 20, and a cutting mandrel 22 between which and a circular cutting knife 24 a web W passes in running from pay-out roll 10, and past guide rollers 18 and 20 to take-up roll 12 in the process of being slitted into two separate webs each of about half the width of the web as in its original form on roll 10.

The web may be of paper, cellophane or other plastic, or of metal foil or, indeed, any type of web material used in industry. The showing of the cutting mandrel 22 and the cutting knife 24 is only to indicate that the purpose of passing the web from roll to roll 12 is merely to process it in some manner. The processing need not necessarily be slitting, but it may be in the form of printing or glazing the surface of the web or otherwise processing the web.

tension-adjusting valve 72,

2 All the mentioned rolls and rollers are mounted so that they may turn on parallel axes. In a strict sense, the part of the machine constituting the take-up roll 12 may be merely'a shaft or thin drum 26, and the pay-out roll 10 may be merely a shaft 28 with which is associated a suitable brake device 30. In this sense, the indicated rolls 10 and 12, therefore, are merely rolls of web material. Except where essential to an understanding of the invention, shafts and supporting framework have been omitted, as the type, disposition, and conventional manner of support of such parts are well known to those familiar with this art. f

The web W is caused to move from pay-out roll 10 onto roll 12 to become a part of the latter,'by the driving rollers 14 and 16, which are turned by a suitable motor 32 through a gear 34, suitably keyed to a shaft 68 of the armature of said motor, and

gears

36 and 38 which mesh with and are'driven'by: gear 34; the

gears

36 and 38, respectively, being keyed upon shafts 40 and 42 of rollers 14 and 16. The shaft26 is a floating shaft and the roll 12 of accumulated web material issupported upon and turned frictionally by the two rollers 14 and 16.

The brake deviceY 30,1as illustrated, consists of

brakearms

44, 46, pivoted attheir lower ends at fixed points andlinked together toward their upper ends by a fluidpressure-operated assembly consistingof'a cylinder 48 pivoted to brake-arm 46 and a piston 50, within the cylinder 48, having a rod 52 extending through one end of said cylinder and pivoted to brake-arm 44.

The brake-

arms

44 and 46 are fitted with suitable brakeshoes 54, which engage'shaft 26.to exert a braking force upon the latter. The upper ends .of the brake-

arms

44 and 46 are normally urged apart, tending to 4relieve pressure or contact of the brake-shoes with respect to the shaft 28, by means of a compression coil spring 56, which extends about a rod 58 one end of which is pivoted to arm 44 and the other end of which extends slidably through the upper end of arm 46. The spring 56 is compressed between the arm 46 and a collar 60 fixed upon rod 58 at a point near arm 44.

The motor 32 is supported in opposite walls 62, 64 of a bracket 66 which, in practice, would be mounted rigidly either upon some part of the frame of the machine or upon some fixed element or member adjacent to the machine. The motor isf-supported at its opposite ends., coaxially of the shaft 68, by the walls 62, 64, andthe motorv mounting is such that, except as restrained as hereinafter explained, the body or casingl of the motor 32 is capable of torsionally induced angular or rotary move-` ment relative rto the bracket 66. According to the present invention, a controllable restraint is imposed against such rotation of the motor and, to the extent that sucli restraint permits limited rotation of the motor about its axis, such limited rotation is utilized in controlling the tension in the running web.

In the illustrated embodiment, control of the webs tension is accomplished through instrumentalities which control and/or are controlled by fluid under pressure, and such pressurized fluid is utilized, also, to operate the brake device 30. These instrumentalities comprise a tension-sensing cylinder or dash-pot 70, a tension-adjusting valve 72, a tension-control valve 74, and a gauge 76, al1 arranged substantially as shown in the drawing. f

The tension-sensing cylinder 70 preferably has therein a piston or diaphragm 78 defining, with the casing of the cylinder 70, a pressure chamber 80 wherein is maintained fluid under pressure communicated into it from a main supply pipe 82 through a branch pipe 84, the mentioned and a connecting pipe 86, the pipe 82 of course being connected to the indicated supply of fluid, preferably air, under pressure. Ilfhus, the pres,

; M I l sure chamber 80 constitutes biasing means and is someripherally and fluid-tightly secured, marginal portion .S8

of sueient strength to withstand `pressures developed in chamberr 30. Rigidly 4fixed to the piston 78'is a vpiston rod 90 which extends outwardly through the casing of the Ycylinder 70 and is pivoted at its outer end to an arm 92 which is rigidly mounted on or is a rigid, integral part of the body or casing of motor 32. Chamber 94 of the cylinder 70, through which the piston rod 90 extends, is suitably vented to ambient atmosphere through a port 96. The end of cylinder 70 opposite to the piston rod 90 has a rigid bracket 98, pivoted to a bracket 100 which is'rigidly mounted either upon an` adjacent portion of the frame of the lmachine or upon some other, adjacent, fixed surface. The described pivot lmounting ofthe cylinder 70 is such that said cylinder may oscillate slightly in response to oscillations of the arm or actuating member 92, the pipe 86 of course being at least slightly flexible or flexibly connected to the cylinder 70 to permit the mentioned oscillation of the latter.

The tension-adjusting valve 72 may be a more or less conventional pressure-regulating'valve such as is used on fluid-pressure lines to control the pressure of luid in or moving through such lines. The illustration of the valve 72 in the drawing, while diagrammatic, should su'ice to convey an understanding of the nature of the operation of the valve and the nature of its efect upon other parts of the disclosed apparatus.

Referring to the drawing, the valve 72 is formed with a linepressure chamber 72LP, a regulated-pressure chamber 72RP, and a vent chamber 72V suitably vented to ambient atmosphere lby a port 102. A valve port 104 with a'valve element 106 therein controls the passage of uid between chambers 72LP and 72RP. The valve element 106 is normally held in a closed position in port 104 by means of a compression coil spring 108.

The valve 72 also has manually operable operating means in the form of an adjusting screw 110'having on its outer end a knob or handle 112 by means of which it may be manually turned. The screw 110 is threaded through the top of the casing of the valve 72, and, compressed between its lower end and a centrally apertured, central valving disk 118 of a flexible diaphragm 120, is a compression coil spring 114. The upper end of the valve element 106 is formed as a needle-valve which seats in aperture 116 of valving disk 118, the latter and the upper end of valve element 106 functioning as a valve permitting controlled passage of pressurized fluid from chamber 72RP to chamber 72V in the operation of the device.

By manipulation of the knob 112,'the screw 110 may be turned down to increase the compression on spring 114 and thereby move Valve element 106 downwardly to open port 104. This permits fluid under pressure to pass from chamber 72LP into chamber 72RP, and thence through pipe 86 into pressure chamber 80 of the tensionsensing cylinder 70. When the pressure in chambers 80 and 72RP builds up to a pressure corresponding to the setting of screw 110, the pressure in chamber 72RP, actling upon the underside of diaphragm 120, opposes the force of spring 114, thereby enabling spring 108 to shift the valve element 106 to its closed position in port V104. If, through leakage or otherwise, there should be any loss of pressure in chamber 80,'the reduced pressure on the underside of diaphragm 120 enables spring 114 to open valve element 106 relatively to port 104 suiciently to bring about restoration of the desired pressure in said chamber. If it is ydesired to decrease the pressure in chamber 80 by manual control, the screw 110 is turned up or eased off, thereby reducing the compressive force of .spring .114, which permits valving disk 118 to rise 'to Vcause the upper end of valve element 106 to become un- @essaies j j f,

seated from within the aperture 116, thereby permitting uid from chamber 72RP to pass into chamber 72V and thence through port 102 to ambient atmosphere. The gauge 76 is connected, in the manner indicated, to pipe 86. The graduations on the gauge may be direct pressure indications and/0r direct tension indications.

. The tension-control valve 74 may be substantially vthe same as valve 72 except in having the regulating plunger 122 as a movable control member in place of the screw 110. The plunger 122 is arranged to slide rather than to turn relatively to the valve casing,.and the vouter end'of the plunger 122 is preferably rounded or provided with an integral, ball-shaped end for coaction with a cam 124 which at one end is pivotally mounted upon arm 92 and at its other end is equipped with an adjusting link 126 extending through an aperture in a lug 128 rotatably mounted in the arm y)2. ri`he adjusting link is threaded at the point where it passes through the lug 128 and is provided thereat with adjusting lock-nuts 130 by adjustment of which it is possible to adjust the angularity ofthe cam 124 in relation to the `upper end ofthe plunger 122. The `indicated 'supply of compressed air is connected by pipe 82 to line pressure chamber 74LP `of "the tension-control valve, and chamber 74RP of said valve is connected by a pipe 132 to the brake cylinder 48 in the manner indicated in the drawing.

In operation of the Windingmachine :as diagrammatically illustrated, it may be assumed that ythe motor 3.2 operates only unidirectionally to drive the various gears, rolls, rollers and shafts in the directions indicated directional arrows in the drawing. At the beginning of a pass of the web W to andpast the circular cutting knife 24 or other equivalent web-processing apparatus, the pay-out roll 10 containing substantially the entire length of the web will be at its greatest ydiameter While ,only several or at least very few turns of the web will be on the shaft or drum 26l so that the diameter of the take-up roll 12 will be at a minimum. As the ,pass of the-web progresses, roll 10 progressively decreases in diameter and, consequently, the mechanical advantage in favor of the force pulling the web from the roll 10 decreases in relation to the braking force applied at shaft 28, so that if said braking force is permitted to remain constant, the tension in the web will `progressively increase and thereby the web will become damaged or broken. Such increased tension is reflected in'increased torque at the motor 32 and the disclosed control system of this invention immediately utilizes even a slight increase in such torque to ease theY braking effect and thereby maintain substantially uniform tension in the web during its pass from roll 10 to roll 12,.

Let it be assumed that valve 72 has been set at the beginning of a pass .to what may be termed a normal setting which will maintain such ,pressure `constantly in chamberof valve 70 kas will enable diaphragm .78 toFsupport the body of motor 3.?, against rotation -at that degree of torque which corresponds to the desired degree of web tension. As the pass progresses and the diameter of roll 10 decreases, `the torque at the motor `tends to increase but such tendency Vimmediately causes arm 92 to rotate clockwisely slightly and slightlydepress dial phragm 78 thereby momentarily increasing the pressure in chambers .80 -and 72RP. Such increased pressure `in chamber 72RP causes valving ,disk v118 to rise, thereby opening aperture 116 Vto vent ofi the excess pressure', leaving the arm 92 in its slightly changed, newly acquired position.

The mentioned movement of `the arm 92 to its new .position causes cam 124 to move similarly. and permit `plunger 122 to Vmove outwardly slightly in Vvalve 74, `thereby reducing the pressure in chamber MRP and vin the brake-cylinder 48 to the .extent necessary to give compensation in the braking effect for the reductionthus farencountered in the mechanical advantagejat -the roll s by reason of the reduction in the latters diameter. Such compensation in the braking effect and the described maintenance of uniform torque at the motor 32 assure t substantially uniform web tension throughout the pass.

It will be understood that during a camplete pass of the web, the arm 92 repeatedly undergoes the slight back to its original position in preparation for another Y web-winding operation. Suitable abutments or stops (not shown) may be provided to limit movement of arm 92 in opposite directions and thereby protect the diaphragms in cylinder 70 and valve 74 against being accidentally ruptured.

It should be understood that the concepts of the disclosed improvements may be utilized in various other Ways without, however, departing from the invention as set forth in the following claims.

We claim:

1. Apparatus for controlling tension in a running web moving from a pay-out roll to a take-up roll, comprising a motor connected to the take-up roll for driving the latter and rotatably mounted to permit limited bodily rotation of said motor in response to torque variations thereat resulting from variations in the tension of the web, a brake, independent of said motor and coacting with said pay-out roll to oppose turning of the latter, and tension-control means for controlling the operation of said brake, said tension-control means being connected to said motor whereby to operate in response to said bodily rotation of the motor and connected to said brake to so control the latter as to compensate for such tension variations; said brake being iiuid-operated and said tension-control means including a tension-control valve in controlling relation to said brake and coacting with said motor during the latters bodily rotation to derive adjustment of said valve, proportionate to such bodily rotation; said tension-control means further including a huid-pressure, tension-sensing cylinder coacting with said motor in opposition to such bodily rotation of the latter and a manually adjustable pressure-regulating valve adapted to control uid pressure in said cylinder and thereby control opposition to such bodily rotation of the motor by said tension-sensing cylinder.

2. Apparatus for controlling tension in a running web moving from a pay-out roll to a take-up roll, comprising a motor having a rotary driving element adapted to turn the take-up roll -and a bodily rotatable casing with an integral, rigid, radial arm adapted to undergo limited angular movement with said casing in response to variations in the torque present between said rotary element and said casing, a fluid-operated brake adapted to control the freeness of rotation of the pay-out roll, a tensionsensing lhuid-pressure cylinder coacting with said arm to afford huid-pressure opposition to angular movement of the motor casing, manually operable means for controlling the pressure of fluid in said cylinder acting in opposition to such angular movement, and a pressureregulating valve, coacting with said arm, as the latter moves angularly, to control the supply of fluid to said brake to so vary the latters operation as to compensate for variations of the tension of the web.

3. Apparatus for controlling tension in'a running web moving from a pay-out roll to a take-up roll, comprising a motor connected to the take-up roll for driving the latter and rotatably mounted to permit limited bodily rotation of said motor in response to torque varations thereat resulting from variations in the tension of the web, a brake, independent of said motor and coacting with said pay-out roll to oppose turning of the lat 7 ter, and tension-control means'for controlling the operation of said brake, said tension-control means being con nected to said motor whereby to operate in response to said bodily rotation of the motor and connected to said brake to so control the latter as to compensate for such tension variations; said brake being duid-operated, said motor Vhaving a rigid, radial arm, and said tensioncontrol means comprising a fluid-pressure, tension-sensing cylinder having a diaphragm therein and a rod connected between the diaphragm and said arm, an adjustable pressure-regulating valve controlling the supply of iluid to said cylinder in back of said diaphragm -to oppose rotation of said arm, a pressure-regulating valve controlling the supply of fluid 4to said brake, and al cam on said arm adapted to coact with and control the operation of the latter valve to cause such operation of the brake as willsubstantially compensate for variations in the tension of the web.

4. Apparatus for controlling tension in a running web moving from a pay-out roll to a take-up roll, comprising a lmotor having a rotary shaft connected to the take-up roll for driving the latter and a casing mounted for limited rotation in response to torque variations at the motor resulting from variations in the tension of the web, a variable brake, independent of said motor and coacting with the running web to oppose movement of the latter toward the take-up roll, brakeoperating means for variably operating the brake, a movable control member coacting with said brake-operating means to control the latters operation and thereby control operation of the brake, biasing means yieldably opposing said limited rotation of the motor casing, and an actuating member,

, integral with said casing and arranged to engage and operably move said'control member, upon such rotation of the casing, to control the brake-operating means and the operation of the brake.

References Cited in the le of this patent UNITED STATES PATENTS