US2231171A - Method of and apparatus for embossing - Google Patents

Description

L. E. RAIQD ELCKER METHOD OF AND AfPARATIiS FOR EMBossING Feb. 11, 1941.

Filed Sept. 22, 195B Lsommp E. RAHuEcKER inhentor Gttorneg Patented Feb. 1],

Leonard E. Randecker,

Hammennill Paper PATENT OFFICE Erie, Pa.,. assignor to moan, Erie, Pm, a cornotation of Tennsylvania A plication September :2, 1938, Serial No: 231,147

12 Claims. (01. lot-2s) a This invention relates to the art of embossing. Machines including embossing rolls through which a sheet is passed for receiving impressions of a design therefrom have long been known. While such machines possess the advantages of fairly high operating speeds and ability to handle wide sheets, thelnembosing efiect ls n0t as clear and free as is frequently desired, and this is especially so at high speeds of operation.

An object of the present invention is the provision of a novel method and apparatus for obtaining an improved embossing effect without sacrifice of operating speed, and/or obtaining asgood an embossing efllect at increased operating 1|: speeds. The invention enables roll embossers to be operated at high speeds without interference with the attainment of clear and pronounced 1mpressions from theembosslng rollers. An out-' standing feature of the invention resides in the 20 provision of controlled tension in the sheet as the latter leaves the embcsser nip. More specifically, the invention provides a'zone of relieved tension in the sheet over an area starting before the nip and ending after the hip, and enabling the sheet 25 to conform more freely to the contours of the design impression during its travel between the, embossing rollers. A substantially improved embossing effect is thereby attained at a given opcrating speed, or a clear and free-embossing ef- 36 feet maybe obtained at a higher operating speed.

Further features and advantages of the invention will be hereinafter'described and claimed. In the accompanying drawing: 1 Fig. 1 is a view in elevation, with parts ln,vertical section, illustrating an embodiment for the practice of the invention.

Fig. 2 is a top plan view of said embodiment. Fig. 3 is a diagrammatic view showing a modification. a Y 40 Referring to the drawing, the invention is illustrated in conjunction with an embosser of well-known type including embossing rolls ",1 I, mounted in suitable frames l2, l3. Said em-. bosser also includes a supply roll or unwind stand 45 H from which the sheet of paper orother material I5 is drawn between the-embossing rolls and ontd the storage roll or wind up stand ii. The rolls I 0, II are continuously driven in any suitable way, as by power shaft l1, and gear i3 0 thereon meshing with'gear IS on the shatt of the roll Ill. The sheet may be passed-from supply roll 14' over a roller '20 and. thence between the rolls l0, H, over another roller 2| and-onto thestorage roll IS. the rotation of roll. lll being 55 transmitted through the sheet to'roll n. 7 During its'passage between said rolls l0, H the sheet is embossed,- and since the rolls '10 and "II apply considerable pressure to the sheet passing between them, these rolls I0 and I I serve to pull the sheet irom the supply roll l4. While either 3 of the rolls l3, ll may carry embossing projections, the latter are shown in this instance as on the roll Ill. The roll H maybe formed of suitable yieldable material for enabling the sheet to receive the impression i'rom, roll III, as is well 10 understood in the 'In arrying out my invention, in .the embodiment illustrated in Figures 1 vand 2, I provide a pair of squeeze rollers 22, 23 at the rear of the embossing rolls l0 and II. Said rollers 22 and 23 are driven at such peripheral speed with respect to that of the embossing rolls as to provldr tension in the sheet betweenthe embossing rolls and the rolls 22, 23. This may conveniently be accomplished from shaft ll through a cone pulley 23 and a belt 25 which passes over a cone pulley 23 on a shaft 21, connected by belt 28 and pulleys 23, 33 with the shaft of roll 23. The cone pulleys enable any desired adjustment of the speed of rolls 22, 23 to be obtained, depending 25 I upon the tension'deslred and the slippage oithe sheet at" the rolls 22, 23d By driving the rolls 22, 23 at a peripheral speed slightly greater than thatof rolls III, II, and by positioning rolls 22,

23 as closeas-posslble to the embossing rolls, I

have found that the sheet may bepassed through the embosser rolls under a minimum amount of tension readily controlled.

Another pair of squeeze rolls 3|, 32 is shown in Figures 1 and 2 in'advance of the embossing rolls 35 II, I I, which squeeze rolls are also driven at an appropriate peripheral speed with respect to that of said'embossing rolls. Cone pulley 33 on shaft l1, belt 33, andconepulley 3!, enable said rolls to be driven at the desired speedtrom said shaft, 4

through pulleys 36, 31, and belt 38. "The driving of rolls 3|, 32 at a peripheral speed slightly less than that .of' the embossing rolls and the close proximity of rolls, 3|, 32 .to the embossing rolls provides a zone of'controlled tension between the nip of said rolls-3|, 32, and thenip of rolls 22, 23. The upper rolls 3| and 22 of the pairs of squeeze rolls 3|, 32 and 22, 23 respectively, are preferably held in contact'with the lower rolls 32 and 23 by meansioi spring pressure to provide the desired amount of slippage of the sheet passing iietweenuthese pairs ofsqueeze rolls. Such pressure and slippage are, of course, important factors in controlling tension of the sheet between the two pairs of squeeze r0lls.- Ifdesi-red, the

upper rolls 3| and 22 mayhave spiral surfaces to serve as spreader rolls.

Between the nips of the pairs of rolls 3|, 3 2 and 22, 23 is a zone llIlJWhiOh the tension of the sheet can be controlled independently of that between the. supply roll l4 and rolls 3|, 32, and independently of that between rolls 22, 23 and storage roll l6. Thusbetween the supply" roll l4 and the nip of rolls 3|, 32, and between the storage roll l6 and the nip of rolls 22, 23, the tension of the sheet may be greatly reduced with respect to the tension required in the usual em bossing machine.

It 'is customary to control tension in a shee of paper being embossed by a braking mechanism on the unwind roll, the'amount of tension usually being very high and frequently being so high in order to prevent transverse wrinkles that longitudinal-wrinkles are formed in the sheet. Various devices including spreader rolls and the like have been used to take out such longitudinal wrinkles.

My invention obviates the need for such de- -vices by providing the tension controlling rolls ,just before and just after the nip of the embossing rolls which reduces the free length of the web before and after the embosser nip to a minimum. I have found that this shortening of the free length of the sheet makes it possi-- ble to emboss the sheet while it is under less tensionthan would be possible with longer free lengths of the sheet before and after the embosser nip. The shorter free length of sheet requires less pull or tension to eliminate transverse wrinkles, and this lower tension together with the short free length of the sheet has less tendency to produce longitudinal wrinkles in the -ployed are used as terms of description and not of limitation, and I have no intention, in the to eliminate wrinkles from-the very shortfree length of sheet before and after the embosser nip.

In practicing my invention, the supply roll l4 does not requirethe customary braking. I prefer to apply just enoughof a drag on the supply roll H to keep it from running free. The sheet is pulled by the embossing rolls IO, N and squeeze rolls 22, 23 through the squeeze rolls 3|,. 32, andtension is supplied by adjusting the speed of the squeeze rolls 3|, 32 and/or squeeze rolls 22, 23. The peripheral speed of the driven squeeze rolls 3|, 32- will be more or less slower than the peripheral speed of the embossing rolls, depending upon the amount of slippage taking place between the sheet and the squeeze rolls 3| :32 andupon the tension desired. The squeeze rolls 22, 23 on the'other hand are operated more in order to eliminate wrinkles therefrom. In

fact, by utilizing tension controlling meansim-- vmediatelyin front of and immediately to the rear of the embossing nip, superior embossing results canbe obtained. v I

This controlled zone of tension in the sheet tension in the sheet passing through the possible to carry out the 30 proximate the embosser nip makes it possible to wind up the embossed sheet under verylittle, if any, tension a distinct advantage in many ways. Likewise, the cost of replacing the braking mechanisms on the supply rolls is largely eliminated. In addition, the positioning of tensioning control means just before and just after the embosser nip reduces the free length of sheet to a minimum and correspondingly reduces the amount of tension needed in the sheet to a minimum. The improvement thus effected by embossing under lower tension has in practice made possible the machine embossing of certain types of paper which heretofore required embossing in individual sheets. I In Fig. 3 the rolls 3|, 32 are replaced by a snag roll asse'inbly comprising rolls 39, '40 and 4| mounted in a frame 42 pivoted at 43 and provided with individualbrakes (not shown). The sheet is shown passing under the roll 39, over 20 the roll' 40, and under the roll 4|. It will be seen that byturning the frame 42 about its pivot the tension in the sheet between roll 4| and rolls Ill, may be varied within certain limits by varying the total amount of wrap of the sheet 25 about the rolls 33 and. This snag roll assembly, similar to rolls 3|,32, provides, together with rolls 22, 23, for a-short zone of controlled bossing rolls, making it embossing under less than the usual amount oftension. Suitable means such asa worm and gear operated by a hand wheel (not shown) may be provided for rotating frame 42 and for maintaining'said'frame in any adjusted position about its pivot.

The terms and expressions which I have emuse of such terms and expressions, of excluding 40 scribed or portioiis thereof, but recognize that various modifications are possible within the scope of the invention claimed.

This applicationis a continuation-in-part of my copending application Serial No.' 126,543, filed February 19, 1937;

I claim:

' 1. In combination, a pair of embossing rolls, means for passing a sheet of material therethrough, and adjustable tensioning control means positioned immediately in front of and imme-i diately to the rear of said embossing rolls for applying a variable amount of drag and pull on said sheet, thus providing a zone of controlled tension in the sheet in the zone of the nip of said embossing rolls.

2. The method of embossing comprising passing a continuous sheet of paper or the like from a source of .supply to' a wind-up station under insuflicient tension to remove'wrinkles therefrom at an embosser nip, passing said sheet throughembossingrolls at a point intermediate saidsupply source and wind-up station, and increasing" the tension in the sheet a sumcient amount to eliminate .wrinkles in a zone extending from a 2,231,171 supply source and wind-up station, and increasing the tension in the sheet an amount just sufficient to eliminate wrinkles in a zone extending from a point immediately in advance of the embossing rolls to a point immediately rearward of said embossing rolls.

4. The method of embossing'comprising passing a continuous sheet of paper or the like from a source of supply to a wind-up station under insufiicient tension to remove wrinkles therefrom at an embosser nip, passing said sheet through embossing rolls ata point intermediate said supply source and wind-up station, exerting a retarding force on the sheet by means-positioned immediately in advance of the embossing rolls, and exerting a pulling force on the sheet by means positioned immediately rearward of said embossing rolls, said forces being sufficient to eliminate wrinkles from the sheet between said two means;

5. Embossing apparatus comprising a pair of embossing rolls, means for passing a continuous sheet of material between said rolls, said means including means for engaging the sheet immediately in advance of said rolls to exert a retarding force thereon, and means'for engaging the sheet immediately following said rolls forexerting a pulling force thereon.

6. Embossing apparatus comprising a pair of embossing rolls, a supply station for supplying a continuous sheet of material to said rolls, a wind-up station for receiving the embossed sheet from said rolls, the tension in themajor portion of the sheet between said supply and wind-up stations being insuflicient to eliminate wrinkles,

means in advance of said embossing rolls for exerting a retarding force on said sheet, and means rearwardoi' said embossing rolls for exerting a pulling force on said sheet, said-forces being suflicient to eliminate wrinkles in the portion of said sheet between said two means.

7. Embossing apparatus comprising-a pair of embossing rolls, means for passing a continuous sheet of material between said rolls, means for engaging the sheet immediately in advance of said rolls to exert a retarding force thereon, and

means for engaging the sheetimmediately following said rolls for exerting a pulling force thereon, said two means being adjustable independently of each other for exerting just sumcient forces to eliminate wrinkles in the portion of the sheet placed under tension.

8. Embossing apparatus comprising a pair of embossing rolls, a supply station for supplying a continuous sheet of material to said rolls, a

from said rolls, the tension in the major portion of the sheetbetween said supply and .wind-up stations being insufllcient to eliminate wrinkles, means in advance of said embossing rolls for ex erting a retarding force on said sheet, and means rearward of said embossing rolls for exerting a pulling force on said sheet, said means'being adjustable to apply different degrees of tension to the portion of the sheet therebetween.

9. Embossing apparatus as defined in claim in which the means for engaging the sheet in advance of and following the embossing rolls comprises pairs of positively driven squeeze rolls.

10. Embossing apparatus as definedin claim 6 in which the meansfor exerting a retarding force and the means for exerting a pulling force on the sheet each comprises squeeze rolls provided with I LEONARD n RANDECKER. A

wind-up station for receiving the embossed sheet

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