US2067755A

US2067755A - Tension controlling means

Info

Publication number: US2067755A
Application number: US682173A
Authority: US
Inventors: Jr Herbert L Dyer
Original assignee: Hammermill Paper Co
Current assignee: Hammermill Paper Co
Priority date: 1933-07-26
Filing date: 1933-07-26
Publication date: 1937-01-12
Anticipated expiration: 1954-01-12

Description

' Jan. 12, 1937.

H.- 'L. DYER, JR 2,067,755

TENSION C ONTROLLING MEANS Filed July 26, 1933 INVENTOR JZEI'ZerZ' Z. Dyer, rfn

E GQQMM ATTORN EY Patented Jan. 12, 1937 UNITED STATES PATENT OFFICE mermill Paper tion of Pennsylvania ompany, Erie, Pa a corpora- Application July 26, 1933, Serial No. 682,173 8 Claims. (CI. 34-48) This invention relates to the regulation of tension in a web of flexible material such as paper during the travel thereof from one point to another. In the manufacture of paper the maintenance of proper tension in the traveling paper web has long presented a troublesome and annoying problem. Indeed, were it not for the fact that a web of paper will stand considerable abuse,

-most of the present paper-making machinery would be useless. The web during the passage over a paper machine, is constantly changing in length, becoming longer at some places and shorter at others; and this change, moreover, is not uniform, since it depends upon various factors which are difflcult to maintain constant. As a result, the tension in the web of paper as it passes through the machine is frequently too great or too little. When the tension is too great, the web may break or wrinkle, or it may develop an unbalanced ratio of expanslon or lose some of its tensile strength. When on the other hand, the tension becomes too small, the paper is likely to shift back and forth across the. width of the machine and to wrinkle; and if this slackness occurs in the web entering the calenders the paper will be cut by the latter. A slack sheet leaving the couch roll will be marked thereby; while if the sheet becomes unduly slack in the presses it will run up on the ductors and break down.

The present invention provides means comparatively simple in construction, for effectively controlling the tension in a sheet of flexible material. By this invention provision is made for reliably and automatically maintaining the desired tension in the sheet or web. The invention also enables slack to be readily and emciently taken up. It further provides for maintaining a desired drying effect upon the paper web despite variations in the drying action of drying cylinders. Other features of the invention will be hereinafter described and claimed.

In the accompanying drawing: Fig. 1 is a view in perspective illustrating an embodiment of the invention applied to a web of paper traveling between two drying cylinders.

Fig. 2 is a diagrammatic view illustrating the action of the embodiment shown in Fig. 1.

Referring to the drawing a sheet or web of paper I is shown passing over drying rolls or cylinders 2, 2 of well known type. Two parallel carrying ropes, customarily employed for threading the paper over the cylinders, are indicated at 3--3. In the space between said cylinders there is positioned a tiltable frame including two

rollers

4, 5 which engage the sheet on opposite sides thereof and which are spaced from eaohother in the direction of travel of the sheet. These rollers 4, I are rotatably mounteld in the frame members 8. 1, which are pivotally mounted in bearings I, I, respectively. Provided by suitable brackets 5 l0, II. The axis about which the members 6, I are tiltable or rotatable is, in the embodiment shown, parallel to the axes of rotation of the

rollers

4, 5.

The rollers aforesaid may" be each rotatably 10 mounted on corresponding rods 4', 5, secured at one end in'bosses or extensions l2, l3, respectively, on the framemember 8. At their other ends said rods 4', i are each mounted in a corresponding one of a pair of arms l6, H. The latter. as shown, 15

.extend in opposite directions from, and are secured to, a pair of studs l8, l9 fastened to opposite ends of the frame member I. It will thus be seen that the frame comprising the

rollers

4, 5, and members 6, I, is readily tiltable as a unit, and that atthe same time, due to the provision of the studs l8, l9 and arms I8, I'I, tilting of said frame through the desired range may take place without interference from the carrying ropes I, I. Suitably secured to the frame member 1, as by 25 being splined or otherwise secured to an extension of the shaft 1', through which the member I is iournaled in the bearing 9, is a cam 20 to which is fastened one end of a flexible cord 2i, which passes over the periphery of the cam and carries at its other end the weight 22. It will be readily apparent that due to the action of said weight a torque is constantly exerted upon the shaft 1', and that the'frame comprising the rollers and

members

8, 1 aforesaid is thereby constantly urged in such direction as to maintain the

rollers

4, 5 firmly pressed against opposite sides of the sheet or web. Slack in the web between the rolls 2, 2 is thus eflectively taken up and the web is continuously maintained under tension. 40 If a constant tension be desired in the various positions of tilt of the frame aforesaid, the cam may be designed in accordance with the principles illustrated in Fig. 2. In this view, 0 represents the axis about which the frame including the

rolls

4, 5, is pivoted, while F is the downward force exerted by the weight 22, and constantly tending to rotate said frame about axis 0 in a counter-clockwise direction. E0 is the perpen- 60 dicular distance from the line of action of the force F to the axis 0. T is the total pull in the sheet of paper, tending to rotatesaid frame about the axis 0 in a clockwise direction. MO and N0 are the perpendicular distancesfrom O to the in response to decrease in drying,

lines of actionof 'I. In order to produce equilibrium: I

T(MO and NO) =FXEO Now F is constant, and if T is to be maintained constant despite variations in MO and NO (which will change with variations in the angle a) it will be seen that the periphery of cam 20 should be so designed that the distance E0 is directly proportional to M0 and NO. Should, however, a tension varying with changes in the position of the frame members 6, I and

rollers

4, 5, about the axis 0 be desired, the periphery of cam 20 can be shaped accordingly.

When the tension controlling frame above described is positioned between dryer cylinders 21, 2, as shown, it not only effectively regulates the tension in the web but furthermore controls the drying thereof. The tension of the web of paper passing between adjacent dryer cylinders arises from shrinking of the paper due to drying. .Assume, for example, that a slight decrease in the drying action of one of the cylinders occurs. The tension of the web between the cylinders now tends to decrease, with-consequent lengthening of the web between the cylinders. However, due to the action of the tension controlling frame above described, the tension is maintained undiminished and the increase in length of paper is converted into increased wrap of the paper about the cylinder. In other words, upon decreased drying action of a cylinder the tension controlling frame increases the area of contact between the paper and the cylinder. increasing the drying of the paper by the cylinder. The wrap of the paper around the cylinder is, in short, increased to the point where the increased drying due to increased wrap results in a tension due to increased shrinkage which balances the tendency for a decrease in tension arising from said decreased drying. Un-

due increase in drying action of a cylinder gives rise to such shrinking of the paper between adjacent cylinders as to rock the frame aforesaid clockwise against the action of the weight 22, but the area of contact of the paper with the cylinders is now decreased with resultant decrease in drying to the proper point. It will thus be apparent that, due to the provision of said tension controlling frame the area of contact between the paper and a drying cylinder is automatically increased or decreased to compensate for decrease or increase of drying action in the cylinder, with resultant maintenance of a substantially constant drying effect upon the paper.

While the invention has been specifically described in conjunction with the regulation of tension in a web or sheet of paper, it will be apparent that its utility is not confined to paper and that it may instead be employed for controlling the tension of, or taking up slack in, webs of flexible material generally. I

- The terms and expressions which I have employed are used as terms of description and not of limitation, and I have no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or' portions thereof, but recognize that various modifications are possible within the scope of the invention claimed.

I claim: 1. In combination, a pair ofdrying cylinders adapted to have a web of flexible material passed thereover and to rotate in opposite directions during the travel of said material, means responsive to variation in the drying action of said cyl-' inders for changing the area of contact between said web and said cylinders to compensate for said variation, said means comprising elements spaced from each other in the direction of travel .5

of said web and engaging opposite sides of the latter between said cylinders, and means constantly urging said elements to rotate about an axis spaced from the longitudinal axes of said elements and in such direction as to exert'forces 1 against the sides of said web.

2. In combination, a pair of drying cylinders adapted to have a web of flexible material passed thereover and to rotate in opposite directions during the travel of said material, means engage- 15 able with said web and responsive to variations in the drying action of said cylinders upon said web to cause the latter to bear with constant pressure upon said cylinders despite variations in said drying action, said means comprising elements bearing against opposite sides of said web at points between said cylinders and means causing said elements to exert pressure against opposite sides of said web.

3. In combination, adapted to have a web of flexible material passed thereover and to rotate in opposite directions during the, travel of said material, means engageable with said web and responsive to a tendency of the web to vary in length for causing the web to bear with constant pressure upon said cylinders and over such area as to maintain a constant drying eifect'upon said web, said means comprising elements bearing against said opposite sides of said web at points between said cylinders and means causing said elements to exert pressure against opposite sides of said web.

4. In combination, a pair of drying cylinders adapted to rotate in opposite directions and to have passed thereover a web of flexible material variabie as to length under the drying-action of said cylinders, means engageable with said web and responsive to a tendency of the web to change in length for automatically causing said web to bear with such pressure and over such area upon said cylinders as to maintain the tension in said web constant despite variations in the internal characteristics of said web under the drying action of said cylinders, said means comprising elements bearing against said web at points between said cylinders and means causing said elements to exert pressure against opposite sides of said web.

5. In combination, a pair of drying cylinders rotatable in opposite directions adapted to have area upon said cylinders as to maintain a con- 65 stant tension in said web despite variations'in the internal characteristics thereof under the drying action of said cylinders.

6. In combination, a pair of drying cylindersv rotatable in opposite directions adapted to have 7 passed thereover a web of flexible material variable in length under the drying action of said cylinders, means engaging opposite sides of said web between said cylinders and responsive to a tendency of a pair of drying cylinders 25 said .web to increase in length between said cylinders for automatically taking up the slack in said web and maintaining a constant tension therein while concurrently increasing the extent of wrap or said web on said cylinders and causing an increased length of said web to be exposed therebetween.

7. In combination, a pair of drying cylinders adapted to have a web of flexible material passed thereover and to rotate in opposite directions during travel of said material, and means for taking up the slack in and maintaining a constant tension in the web of material between said cylinders, said means comprising elements spaced from' each other and engaging opposite sides or the web between the cylinders, and means exerting a torque for urging said elements to rotate about an axis spaced from said elements into engagement with said web.

8. A device in accordance with claim 7 in which the urging means transmits its torque to the elements by ofiset crank arms whereby an unobstructed passage may be maintained from 10 one cylinder to the other.

HERBERT L. DYER, Ja.