US2981134A - Method for web feeding and cutting - Google Patents

Description

A ml 25, 1961 o. D. JOHNSON 2,981,134

METHOD FOR WEB FEEDING AND CUTTING Filed Dec. 30, 1957 3 Sheets-Sheet 1 --P4PE/-? GU/DE OVERFED /0 LOW TENS/0N 1W WEB 20 DRIVE/V FEED /DLER ROLL ROLL NORMAL TENS/0N P= Heavy var/able /N WEB (Pr/0r ar/j pressure OVER/ E0 ROL L INVENTOR 0/ iver D. Johnson BY 5 4w 5W ATTORNEYS April 1961 o. D. JOHNSON 2,981,134

METHOD FOR WEB FEEDING AND CUTTING Filed Deu. $0, 1957 3 Sheets-Sheet 2 n 4 o L/ h/ IGJSU/E-IIO inden/a/fon of web M 1. f p A IDLEH' \i; 7 CUT OFF i Varma/ fled l l 2 WEB (Exaggera fed fhfc/rnesg) FEED ..P- ROLL laler rofafes faster than feea' rol/ Each revo/uflbn 0f feed rol/ feeds a given length of compressed wea material, which fhereaffer expands mLER K L2 ENS/0N C'OMFRESS/ON FEEL) lDLE k,

5/ e/ched wen e/emenf F 60m ressea' Web FEED EULL ale/:30!

INVENTOR O/fver D. Johnson BY gW ATTORNEYS A nl 25, 1961 o. D. JOHNSON 2,981,134

METHOD FOR WEB FEEDING AND CUTTING Filed Dec. 30, 1957 5 Sheets-Sheet 3 '3' 4, 47: Each revo/uf/on af feed 1 6 roll feeds a given /eng/h of sfrefched web maf- Hr/GI which fhereaffer FEED ROLL sharfens 2Q 4w A Compressed web fmorma/ web e/emem F5150 Sfreza/nsa web e/emanf Range of Con/ra/ IN ENTOR U/iver [7. Johnsan BY W 5 W ATTORNEYS United States Patent ce 2,981,134 METHOD FOR WEB FEEDING AND CUTTING Oliver D. Johnson, Vestal, N.Y., assignor to International Business Machines Corporation, New York, N.Y., a .corporation of New York Filed Dec. so, 1957, Ser. No. 705,896 2 Claims. 01. 83-18 This invention relates to a method for web feeding and cutting and more particularly to a method for controlling the feeding rate of a web by adjusting the amount of tension or compression in the surface layer of the web in non-slipping contact with a driven feed roll, by changing the peripheral contact area between a relatively slack web and a driven feed roll or a backing idler roll, and

cutting the so-fed web by a cutter synchronized with the cut in segments, it is especially desirable to be able to minutely adjust the feeding rate of a web so that a cutter operating at timed periodic intervals will cut a predetermined length ta'bulator card from the web. A known ,device for minutely varying the speed of a paper web of this type has means for varying the degree of compression on the top and bottom sides of the web passing between the feedrolls by varying the pressure exerted by the feed rolls. However, the degree of adjustment which is attainable using this device is quite limited. Therefore, it is an object of this in vention to provide a simplified device and method for adjusting the feeding rate of a paper web by merely changing the feed angle of the web while under relative low stress and therefore the amount that the web wraps around one of the feed rolls.

This invention contemplates the feeding of a web between a driven feed roll and a backing idler roll, which rolls exert a relatively low pressure on the web. The web may be fed by overdrivlen rolls for the purpose of produciiig a low tension in the web, i.e., the web is relatively slack, There is no slippage at the feed rolls and since the feed roll pressure is low there is also no indentation of the web material, thus each roll has a peripheral speed -equal to the speed of the surface of the moving web contacting the roll. When the web is fed straight to the rolls 'on a tangent which is perpendicular to a line connecting the axes'of the rolls, the'amount of web which passes through the rolls will be equal to the distance that any point on the driven feed roll has moved in this unit of time, since there is no slippage and the speed of the web surface is equal to the peripheral speed of the driven feed roll. If means are provided to vary the feed angle from this straight line thereby wrapping the web slightly around the driven roll or idler roll, the applicant has discovered that appreciableidifferences in the rate of feed will result. This phenomenon is believed to be due to a stressingof the fibers of the surface layers of the web while it is passing through the feed rolls to cause the driven feed roll to feed either a compressed or stretched length of surface layer per revolution, which layer later returns to its unstressed condition and length to give the desired results. By cutting the sheet behind the feed rolls with a cutter r 2,981,134 Patented Apr. 25, 1961 ,2 synchronized with the feed rolls, the length of sheet cut will vary with the feed angle.

Other objects and advantages of this invention will be apparent from the following detailed description considered in connection with the accompanying drawings wherein:

Fig. l is a schematic showing of the preferred embodiment of the invention;

Fig. 2 is a schematic showing of one prior art adjustment means;

Fig. 3 is a schematic showing of one type of paper guide and of registration marks on the feed rolls which may be used to show the variations in feed of the web which occur in practicing this invention;

Fig. 4 is a schematic showing of the feed rolls and Web during normal straight feed when the speed of the web is equal to the peripheral speed of the feed roll;

Figs. 5 and 6 are schematic showings of the feed rolls and web, greatly exaggerated, to explain the theory involved when the rate of web feed is greater than the peripheral speed of the driven feed roll;

Figs. 7 and 8 are schematic showings of the feed rolls and web, greatlyexaggerated, for an explanation of the theory of the invention when the rate of web feed is less than peripheral speed of the driven feed roll;

Fig. 9 is a schematic showing of the'web and the range of control that can be effected.

Referring to Fig. 1, a web 10 may be fed over a conventional idler roll 12 and the web at this point has a normal tension or stress therein. For example, the stress at this point might be two lbs. per inch of web width. The web is then fed over two overfed rolls 16 and 18, which rolls are driven with a peripheral speed faster than the speed of the moving web to decrease the tension in the web. the tension in the web after leaving the overfed rolls is relatively low, for example approximately 2 oz. per inch of web width, with the rolls 16 and 18 having a 5 percent overfeed. The web then passes between a driven feed roll 20 and a backing idler roll 22. The idler roll suitably mounted to exert a low pressure on the moving web, as, for example, ,2 lbs. per inch of width of the web; This pressure is sufficient to prevent web slippage while being low enough to prevent indentation of the web. A movable guide'24 is adjustably positionableto bend the moving web' and thereby vary feed angle from a straight feed which is a tangent perpendicular to a line connecting the centers of the 'feed rolls to an angular feedwhi ch causes themoving web to contact more of the periphery of one or the other of rolls 20 and 22. Thus, the movable'guide may act tovary the wrap of the web around eitherv of the rolls 20 and 22. A cutter such as indicated schematically at 28 may be provided for cutting the webinto segments after it leaves the feed rolls.

1 invention depends for its results on the effect produced by bending the unstressed web, thereby stressing the fibers of the surface layers of the web. Since the fibers are already indented and under substantial vertical compression with the heavy pressure of conventional means, bending the web by varying the web feed angle would have little or no effect.

Fig. 3 shows the feed rolls and one form of movable guide for varying the feed angle. The idler roll pressure is relatively low and has been adjusted, as stated above,

so that there is no slippage between the rolls and the web, and also there is no indentation of the surface of the web or of the feed rolls. Each roll 20 and 22 then has a linear peripheral speed exactly equal to the speed of the adjacent web surface, since there is no slippage. With the web feed straight between the rollers, the two registration marks r on the upper idler and lower driven rollers 20 and 22 will maintain exact synchronism since their speed is the same. When the paper guide 24 is moved downwardly to A such as by manually tilting it about pivot point x, the mark on the idler will, by stroboscopic effect, appear to gradually move in the direction of a because for each unit length of web surface which passes the driven feed roll 20 in one revolution thereof a greater length of web surface will pass the idler roll 22, this phenomenon is explained below. When the web is bent up to the position B the mark on the idler will walk back in the direction of b because for every unit length of web surface which passes the feed roll in one revolution thereof a lesser length of web surface will pass the idler roll but yet, as stated above, no slippage occurs at either roll.

Fig. 4 is a schematic showing of the web when it is fed on the straight normal feed line with no wrap around either of the rolls 20 and 22. In this instance, the effective length of the web feed for each revolution of the feed roll is equal to the circumference of the feed roll and when the web is severed by cutter 28 in synchronism with each revolution of the feed roll then the length of segment severed would be equal to the circumference of the feed roll.

Reference may be had to Figs. 5 and 6 for an explanation of the theory of why the feed rate will be increased when the feed angle is adjusted such that there is more web wrapped around the driven feed roll 20. With the web wrapped around the feed roll the fibers adjacent the upper surface of the web are stretched while the fibers adjacent the lower surface of the web are compressed due to the bending of the web. A normally unstressed length of web material would be shortened at the surface contacting the feed roll 20 due to the compression and lengthened at the surface contacting the idler roll 22. While the feed roll is feeding a unit length of compressed web material, the middle layer of the web will be advancing at a greater rate. The amount of web fed at the middle layer is the actual amount of web which passes between the rolls, and when the web straightens out again the bottom compressed layer expands while the top stretched layer contracts, but the middle layer remains the same. Hence, the distance through which the middle layer has advanced in any unit of time will be actually greater than the length of compressed web layer fed in the same unit of time by the feed roll, and when this compressed length subsequently expands the lengths of the cards or segments severed from the web at periodic intervals will be increased. In this situation, each revolution of the driven feed roll 20 feeds a length of compressed web material which expands after passing through the feed rolls to give a longer length.

For the opposite effect, that is feeding less web length er unit of time, reference may be had to Figs. 7 and 8. With the web wrapped around the idler roll 22, while the feed roll 20 turns one revolution it will feed a length of stretched web material; that is, it will feed a length of the surface layer contacting roll 20, which is actually less than a length of uns tretched web material, the middle web layer. The web surface layers then return to their unstressed condition after passing through the rolls to give a shorter length of material.

As will be apparent from the above explanation, the

range of control or adjustment of the web feed will be equal to the sum of the amount of shortening under compression which will occur in any unit length of unstressed web surface when it is wrapped to the maximum extent around the feed roll plus the amount of lengthening under tension which will occur in the same unit length of unstressed web surface when the opposite surface of the web is wrapped to a maximum extent around the idler roll, see Fig. 9.

The rate of feed of the web may be adjusted to vary or control the length of segment cut from the web by a cutter 28 operating at timed periodic intervals. Thus the setting of the guide 18 controls the length of cards cut from the web in the environment described above.

As shown in the illustrated embodiment, one means of adjusting the feed angle of the paper web between the feed rolls is by a manually tiltable guide. It is, however, within the contemplated scope of this invention to adjust this feed angle and hence the feed rate by a guide means which may be movable automatically in response to sensed lengths of segments cut from the web. With such an arrangement the length of segments cut can be controlled by measuring the lengths of these segments and utilizing the measurement to position the guide means.

While applicant has disclosed a novel method and apparatus for adjusting the feeding rate of a paper web to enable one skilled in the art to practice the invention, the disclosed embodiments are considered illustrative only and not limiting, as this invention is limited only by the spirit and scope of the appended claims, wherein applicant is entitled to a reasonable range of equivalents.

What is claimed is:

1. The method of cutting sheets of variable length from a continuously moving web of flexible material comprising the steps of providing a moving Web having substantially no longitudinal tension therein such that the surface fibers on both surfaces of the web are under no appreciable longitudinal stress, passing the web between the nip of a driven feed roll and a backing idler roll with said rolls exerting a low pressure on the web, the pressure being incapable of indenting the surfaces of the web but sufiicient to prevent slippage between the web and said rolls, cutting sheets from the portion of the web leaving the feed roll at a rate which has a fixed time relationship to the speed of the feed roll, and determining the length of each sheet cut from the web by selectively varying the amount of web wrap-around said rolls at the input side thereof whereby said rolls will cause a stress in the surface layers of the web and the amount of web fed per revolution of the driven feed roll will vary with the amount of wrap-around.

2. A method of cutting sheets of variable length from a continuously moving web of flexible material comprising the steps of feeding the web in contact with overdriven rolls, then passing the so-fed web between a constant-speed feed roll and associated idler, the overdriven rolls insuring that substantially no longitudinal tension exists in the web prior to contact with said constant-speed roll and associated idler, cutting sheets from a portion of the web leaving the constant speed feed roll at a rate which has a fixed time relationship to the speed of the feed roll, and determining the length of each sheet cut from the web by selectively controlling the angle between the respective directions in which the web approaches and leaves the feed rolls.

References Cited in the file of this patent UNITED STATES PATENTS 2,321,342 Weiss June 8, 1943

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