US1538887A

US1538887A - Apparatus for controlling tension

Info

Publication number: US1538887A
Application number: US508548A
Authority: US
Inventors: Charles E Carpenter
Original assignee: Individual
Current assignee: Individual
Priority date: 1921-10-18
Filing date: 1921-10-18
Publication date: 1925-05-26
Anticipated expiration: 1942-05-26
Also published as: US1652299A

Description

May '26, 1925. 1,538,887 1 C. E. CARPENTER APPARATUS FOR CONTROLLING TENSION Original F iled Oct. 18, 1921 2 Sheets-Sheet 1 11v VENTOR.

- 6M 2 0 92 5 WM '1 ATTORNEY C. E. CARPENTER APPARATUS FOR CONTROLLING TENSION Original Filed Oct. 18, 1921 2 Sheets-Sheet 2 INVENTOR 2 GM M W M ATTORNEY I Patented May 26, E925.

CHARLES E. CARPENTER; OF NE'W YORK, 1N. Y.

APPARATUS FOR GON'JJROIiLING TENSION.

Original application filed October 18, 1921, Serial No. 508,547 Divided and this 18, 1921. Serial No. 508,548.

To all whom it may concern.

Be it known that I, CI-IARLEs E. GARDEN.

' material. This invention was particularly devised, and is especially adapted for use in controlling the tension ofaweb of paper as it is fed into a newspaper printing press, a waxing machine, slitting rolls, or other apparatus to which paper is supplied. The invention, however, is not necessarily limited to use with webs of paper but is generally useful where it is desirable to maintain a constant tension on web or strand-like material as the latter is being drawn into or through apparatus.

In carrying out my invention I put the web or strand-like material under the de sired tension by transmitting through the material the force required for driving a pump and regulate, as by variably throttling the pump outlet, the differential be tween the pressure at the pump inlet and the pressure at the pump outlet as required to make the driving force proportionalto.

the tension desired. Specific objects of my invention are to provide ample and effective power transmitting connections to the pump proper from the web, and a simple and effective valve mechanism for regulating the compressor outlet pressure.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, and the advantages possessed by it, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred embodiments of my invention.

Of thedrawings:

Fig. 1 is aside elevation;

Fig. 2' is a section taken on the line 2-2 of Fig.

g 3 d 4 are views taken similarly to Figs 1 and 2 respectively, illustrating a modified construction; i

Fig. as a section on the line 5-5 0 Fig. 2; and

Fig. 6 is a viewtaken similarly to Figll illustrating a modified form ofcontrol valve mechanism.

In the drawings A represents the framework of a'printing press or like apparatus provided with open bearings A for the ends of the spindle B for a roll B of paper-B.

which is drawn from the roll by the, feeding mechanism of the machine, conventionally illustrated as comprising a pair of rolls A A represents the usual guides along which.

the spindle of a fresh roll being placed in the machine may be rolled into the bearings A. The necessary tension is impressed on PATENT OFFICEpF.

application filed Qctober.

the web of paper B running from the sup ply roll to the feed rollsA by means of a frictional driving connection between the periphery of-the roll B and a pump C. The, pump C may be either a pump for liquid as oil or water, or'a pump for gas, and may be either a reciprocating pump or a rotary pump. Advantageously, however, the pump is a rotary air compressor of the positive displacementtype, and in the drawings I have shown a well known form of this-type of compressor comprising a rotary body G with .vanesor blades C pivotally connected thereto and working on a cylindrical pump chamber' C which is eccentrically disposed with respect tothe rotating shaft C of the pump.

The driving connection between the pump shaft C andthe periphery of the roll B comprises a pair of belts D, one at each end of the pump. Each belt D runs over a pulley D secured to the corresponding end of the pump shaft C, and a pulley l) journalled at the end of a corresponding arm' E pivotally connected to a'fixed support which, advantageously as shown, is the hous:

ing of the pump C. Each armE is proportioned and arranged that the underside of the corresponding belt will move from the position shown in full lines of Fig. 1 to that shown in dotted lines of the samefigure and remain in contact with the periphery of the roll as the latter is unwound and diminishes in diameter, Each armE isprov vided with an extension E- from which is suspended an adjustable weight F, and the parts are so relativelyproportioned;and arranged that an approximately constant contact pressure between each belt D and'the periphery of the rollis maintained as the belt moves from the position shown in full lines to that shown in dotted lines'inallig. 1.

By providing two belts D instead of a single belt Iam able to obtain the necessary compressor driving force when the roll is a full length roll, without subjecting the 'roll to unnecessary pressure when the roll is only half length. Ordinarily the total tension from the webneeds be'but'half of whatit should be when the roll is of full length, and with the roll of half length one of the belts may be held outof engagement with the roll.

The force required to drive the com pressor, and thereby the tension put upon the web, is controlledby a valve Gthrottling the compressor outlet and thereby controlling the pressure difierential between the pump inlet and the pump outlet. The valve G ass'hown comprises a casing formed with vtwo chambers G and G connected by a port G rectly to the outlet of the compressor 0, and

The chamber G is connected dithe chamber G is provided with outlet ports G The outlet ports G are formed in the wall of a cylindrical extension G of the chamber G in axial alignment with the port G When :the valve member H is in its fullycolosed position the inner end H of the valve member closes the port G and :the valve portion I-I'? closes the port G and the parts are preferably so proportioned and arranged that the valve member H must move appreciably away from the position in! which it closes the ports G before the portion H begins to uncover the ports G The valve member H is urged toward its closed position by a spring I located in aspring housing forming an extension of the guide member G which is open at its outer end. The spring I acts between the valve member H and a spring follower K which may be moved toward or away from the valve member, to vary the tension of the spring I, by means of a screw spindle threaded through the I outer end of the casing G and provided at its outer end with a hand wheel K Advantageously, as shown, the valve chamber Gr is connected to a small pressure equalizing reservoir G.

In operation the compressor O is operated through the belt or belts D at a speed proportional to the speed of travel of the web B drawn away fromthe supply roll B, and the tension of the. web B is due very largely to the throttling effect of the controlling valve G. Of course a portion of the web tension is due to friction losses in the bearings for the rollspindle, in the pump, and in the driving connection between the pump and the periphery-of the roll B, but with suitably designed apparatus these friction losses create but a small portion of the total'tensio-n required.

The tension may readily be varied to accommodate different kinds or weights-of paper or other varying conditions of operation by rotating the hand wheel -K and thereby adjusting the tension of the spring I. As the speed of the web changes in starting and stopping the apparatus and the volume of air passing through the pump correspondingly varies, the movable valve member I-I movestowa-rd and away from its fully closed position,'but if thespring I'be made long enough so thatthese movements of the valve member H do not materially cha-nge'the tension of the. spring I,the pressure at the compressor outlet may be maintained practically constant while the compressor is in operation, regardless of speed of the compressor and the volume of air passing through it. In consequence the compressor impresses practically the same force on the roll tending to "retard its rotation at high speeds as at low speeds.

At the instant of starting the apparatus into operation from a condition of rest, however, the compressor opposes no initial retarding force on the roll except that due to friction, for when the compressor stops operation, the pressure at its outlet falls almost instantly to an equality with the pressure of the atmosphere by reason of the inevitable leakage from the system. The fact that the compressor exerts no resistance to the initial movement of the roll in starting other than friction resistance is advantageousbecausethe inertia of the roll and the frictional resistance to starting the web into motion puts ample tension on the roll at that time. It is to be understood, of course, that the frictional resistance to starting roll B into rotation from a condition of rest is greater than the frictional resistance to the rotation. of the roll after the latter is rotating. A small fraction of a turn of the roll is sufiicient, however, to build up a pressure at the discharge of the pump which creates an appreciable tension upon the paper. This quick increase in tension is especially advantageous in n'event-ing over travel of the roll and consequent fcstooning of the web in inching which the web must be intermittently ad vanced a few inches at'a time.

The small volumetric capacity preferably provided between the compressor chamber C and the port G facilitates a quick build ing up of the tension creating drag of the compressor as the latter starts into operation. This quick building up of a substantial tension in starting may be augmented,

operations in as shown, by making the portion H of the valve member H exposed to the pressure in the compressor outlet when the valve member H closes-the port G smaller than the portion exposed after the port Gr is opened. The chamber L .serves as a pressure equalizing device tending to prevent fluctuations in the pressure at the pump outlet. The location of the chamber L at the outlet side of the port Gt prevents the volumetric capacity of this chamber from being a factor retarding the rate at which the compressor outlet pressure increases in starting.

The compressor and its driving mechanism by which the tension is regulated is comparatively inexpensive to construct and install, and may readily be applied to" exist ing printing pressesand other apparatus in which such tension regulating provisions are desirable as well as to new apparatus. The apparatus is not only reliable in opera,- tion but ordinarily requires little attention. hen a change in web tension is made desirable by changes in operating conditions,

this is quickly and easily effected by adjustment of the hand wheel K but ordinarily no adjustment of the apparatus is required as the apparatus isstarted, runs up to speed and is again slowed down and stopped. Since with my invention, the tension of the paper depends upon the pressure at the pump outlet, which may easily be regulated and measured, the tension maintained is a definite thing which may be known with exactness. This means in practice that apparatus equipped with my improved tension control means may operate with a tension lower than is employed with tension controlling provisions heretofore employed in which the tension maintained is more or less indefinite and unknown, and in consequence is maintained higher than is required in order to insure that the tension is high enough. Excess tension. is undesirable not only because it tends to increase the frequency with which the web is broken, but also because it increases the driving power required for drawing the paper through the apparatus and involves unnecessary wear due to friction.

The modified form of my invention illustrated in Figs. 3 and 4t differs from that shown in Figs. 1 and 2 in that friction pulleys DA are substituted for the friction belts I). Each friction wheel DA is journalled .in the free end of the supporting arm E and is connected to a sprocket wheel or pulley D over which a corresponding sprocket chain or belt runs to and about a sprocket wheel or pulley D secured to the corresponding end of the pump shaft C. "With the form of my invention shown in Figs. 3 and 4, the parts should be proportioned and arranged so that each friction wheel DA Wlll engage with the roll D when the latter is very small as shown in dotted lines in Fig. 3.

l/Vhile in general the delivery outlet pres sure of the compressor should remain constant when the speed of the compressor is proportional to that of the web as it is with the apparatus shown, it is sometimes found desirable to reduce the tension when the sup ply roll is nearly unwound. At that time irregularities in the contour of the roll sometimes develop which tend to make the feed a little irregular and as a result makes a lower average tension desirable to avoid a momentary increase in tension to the web breaking point. To take care of this condition I have devised means shown in Fig. 6 for automatically reducing the compressor outlet pressure when the supply roll is nearly unwound. The controlling valve shown in Fig. 6 differs from that shown in Fig. 5-only inthat the tension adjusting screw K is not threaded through the outer end of the tension G of the valve casing but through a cap member M fitting over the outer end of the extension G. The cap member M is normally held against the end of the valve casing extension G by a spring M surrounding the extension Gr between a shoulder Gat the outer end of the extension, and a shoulder or flange M at the inner end of the cap member M. The spring should be a stiff spring and withithe parts in the position shown in'Fig. 6 should be under tension greater than the maximum tension imparted to the spring I so that normally, the cap M is seated against the end of theextension Gr and the tension of the valve controlling spring I is wholly under the control of the hand wheel K. When the roll is nearly unwound, however, the cap member M is automatically moved outward against the tension of the spring 0 to thereby relieve the tension of the spring I and correspondinglyreduce the compressor outlet pressure. The means provided for thus moving the cap member M comprises a lever O journalled at O and having bifurcated arms engaging trunnions' M carried by the cap member M. Another arm of the bell crank lever O is in position to be engaged by a cam extension E of the arm E of the power transmitting mechanism as the arm E moves into the position occupied by it when the supply roll is nearly exhausted.

Certain generic features of invention possessed in common by the apparatus disclosed herein and by other forms of apparatus devised by me are claimed in my co-pending application, Serial No. 508547 filed at even date herewith.

While in accordance with the provisions of the statutes I have illustrated and described the best form of my invention now known to me, it will be apparent to those skilled in the art that changes may be made and actlng in the form of the. apparatus disclosed'without departing from the spirit of my invention as set forth in the appended claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. The combination with means for advancing web or strand-like material, of means controlling the tension of said ma terial comprising a pump, driving means therefor engaging the material and thereby driving the pump at a speed proportional to that at which the material is advanced and means tending to maintain constant the force required to drive the pump not with standing variations in pump speed.

2. The, combination with means for'advancing web or strand-like, material, of

means controlling the tension of said material comprising a pump, and driving means therefor engaging the material and thereby driving the pump at a speed proportional to that at which the material is advanced, and means for maintaining an approximately constant pump outlet pressure notwithstanding variations in pump speed.

8-. The combination with means for advancing web or strandlike material, of means controlling the tension of said material comprising a pump driven by the ten sion of the material at a speed proportional to the speed at which the material is advanced, and a valve casing formed with two chambers one of which is connected to the compressor outlet and the other being provided with anoutlet port, a port connecting the two chambers, a valve member controlling saidports and loaded with a tendency to close, but tending to open under the fluid pressure in the casing, and arranged to open the last mentioned port before opening said outlet port as the outlet pressure builds up in starting.

4. The combination with means for advancing web or strand-like material, of means controlling the tension of said material comprising a pump driven by the tension of the material at a speed proportional compressor outlet and the other being formed with an outlet port, a port connecting thetwo chambers, a valve member controlling said ports and tending to open under the fluid pressure in the casing, and arranged to open the first mentioned port before opening the second mentioned port, and means for impressing a regulable force on said valve member tending to close it.

.5. Means for controlling the tension of a travelling web comprising in combination a pump adapted to be driven by said web, a valve regulating the pump outlet pressure and comprising a valve casing formed with a chamber connected to the pump outlet and with a second chamber, and with an escape port from the last mentioned chamber and with a port connecting the two chambers, a movable valve controlling said ports and subjected by the fluid pressure in the casing to a force tending to open said ports and arranged to open the connecting port before opening the outlet port, and provisions for subjecting said valve member to a regulable force tending to hold it in its closed position.

6. The combination with apparatus comprising means for supporting a roll of material wound about a roll spindle'and for engaging the ,material and unwinding it from the roll, of means for putting thema terial under tension comprising a pump, means for driving the pump by force transmitted through the material at a speed proportional to the speed at which material is unwound from the roll, and means regulab' ing the pump outlet pressure including provisions responsive to the amount of material on the roll for reducing said pressure when the amount of said material becomes very small.

Signed at New York, in the county of New York and State of New York, this 17th day of October A D. 1921.

CHARLES E. CARPENTER.