US2218430A - Apparatus for compensating hygroscopic expansion of paper in printing presses - Google Patents

Description

Oct. 15, 1940. MAKARlUs 51- AL 2,218,430

' APPARATUS FOR COMPENSATING HYGROSCQPIC EXPANSION.

OF PAPER IN PRINTINGYPRESSES 'Filed July 27, 1939 2 Sheets-Sheet l rs 2/ a /J INVENTORS ATTORNEY 2,218,430 APPARATUS FOR COMPENSATING HYC-ROSCOPIC EXPANSION Oct. 15, 1940. T. MAKARIUS ET AL OF PAPER IN PRINTING PRESSES Filed July 27, 1959 2 Sheets-Sheet 2 INVENTOR T6 ea do re A Ira/v as Jd "(as Ver ehz BY ATTORNEY Pa nted Gears, 1940 i APPA ATUS ron comnxsa'riuonyoao ISCOPICEXPANSION or-raraam-rnmr-n i INGPRESSES I Q Application July lssaserfiamazsesso 6 Claims. (01. 271-48) This with: relates to, the printingjart, and more; particularly refers to improvements in multi -co lor printing processes-andin printing presses a used in connection therewith.

5 In,multi-color printingit is of, the utmost im-- portance itoiinsure exact juxtaposition of successiveimpressions if the result is to bea color composition in which the-colors blend harmoniously with one another without any evidenceofoifset printing, 1 V I The necessity of thus producing; perfect work calls for aagreatdealof skill onthe part of the printer, who must be expert in arranging the.

printing platesfon the various impression cylin- 1 ders aswell as the paper guides and other elements controlling the travel of the paper sheets through the press, in-order to coordinate their functions in perfect timing and perfect register. ,One of; thediflicultieswithwhich the printer has to contend, is-th'e tendency of paper to absorb moisture whichirequently causes the lengthandbreadth of the paper sheets to vary from one impression to another, For instance, .it frequently happensthat a paper sheet which has been sublooted to; a, flrstimpression may be .found to be somewhatlongerand' wider when it ispassed to theflnext impression, especially, if between impressions theisheet has had a chance to absorb moisture from ;the surrounding air and to have become impregnated with the ink of the first impression. I, i

.It follows,lthat if some compensation, counterbalancing suchrvariationsof size, is not provided,

the various impressions will fail to be in exact {register ,andsthe result will be an inferior ortotally defective composition. I 1

Such increases as may occur in the length of the sheet, that.is.,.in the direction of the press ed. maybem e s ted w th eqmna a v h s byadiusting the distance-of the printing plates, from the center of the printing cylinde rupon v 4s swili aues dte end,- adeouate provisions-foradjustment are us'u-v allyl prqvided in print i yl ies ses of; standard de signandK no-particular problem in insuring exact register-of the various impressionsmaybe said to;

exist. J

The variationswhich take place "br eadth r the shee s. l-h evge t con i u wa P o m tonne-Pr nt r ca se o ou o l 1 quate provisions for compensating adjustment e variations as may ,have, taken plac in thelength of the sheetsg To this.

have been heretofore provide, 7 these conditions skilled operators w l sort tosome makeshift expedient, wh h m'ayii prove the register of the successive impressions to Q a certain extent, but whiohgrealways ,uncertain in their operation andv may'h be dependedupon to insure uniformly good resul Furthermore, such makeshiftha r ng ements as the printer, may resortto usually consume a." great deal of timeand sinee they generally require a 10 number of printing tests they alsoresult in a ma terial wastage of. paper iifl en{thepaper is very hygroscopic or when the; airis. highlyfcharged with moisture, the expansion'of the paper may be i t mes such that its adequatecompen sationwill be very diflicult, if not impossible, to achieve. Under abnormal conditions of'humidity, a paper sheet orige inally about four feet wide may expand asmuch" as a quarter ofan inch or more and an expansion of one-eigthth of, an inch is not at-all uncommoh. 20

The primary object of this invention.istoprc vide, in, a printing press, a novel and improved device for compensating the'hygroscopic "expam i sion taking place in the paper sheets transversely to the direction of the press feed, whereby said 5 sheet may be f drawn in? more or less substantially so as to restore the original distance between its side edges andin'sure correct register of successive impressions.

A further object is to provide,' in a printing 30 press, a device of the character specifie'd,.of a simple and eifective design, said device being easily mounted on a standard press and being, controllable from a distance without interference with the normal operation of the press.

Other objects and advantages ofthe present invention will more fully appearas the description proceedsand will be 'set forthfand claimed in the appended claims.

our invention s 111u tre tea by ,ivay st ins; 5'

ni mnen awih rihvlii h-i; v .i ri s i ai lyi w q vefit ll el l y platform between two-imbr sion 'fcylinders printing press, equipped with device embodyin oim ve i on';.-, i,

;Fig,2 isiayert i longltudinal sect v ,.Fig. 3 narrontendvi w o'fl-t'he vs'am 8, i f N Fig. 4 is a plan? f'the frontj iljnit of uq',

device for 'compen sati'ng the hygro soqpicjexpan i sion occurring at the front end .of t'l ie sheeti "5o as I1aa d .v ew n el'vat nit xofi Y L Fig; 6, is a' vertical ongitud nal: section or the same," in an nlarged scale, I taken thiough, line' omen Fig. '7is a'plan view of therear unit of our 55 device for compensating the hygroscopic expansion taking place at the rear end of the sheet;

Fig. 8 is a vertical longitudinal section thereof: and

Fig. 9 is a side view in elevation thereof.

Referring to Figs. 1 to 3, l8 designates an impression cylinder in a multi-color printing press, ll designates another impression cylinder for the next color impression and i2 generally designates the delivery platform between the two cylinders, the sheet discharged from cyliifder 18 being delivered to said platform to be fed to the grippers (not shown) serving the next impression cylinder.

The actual delivery to the grippers is effected. by a plurality of longitudinally directed endless feed tapes l3, l4, l5, l6, riding over end pulleys i1. 18, the operation of said feed tapes being intermittent and being timed with the operation of the impression cylinders.

The delivery platform usually also comprises 7 a number of longitudinally directed bars I3, 23,

located between adjoining feed tapes, and a plurality of front end supports 21, adjustably clamped onto a transversely directed round bar 22.

As we have previously explained, according to our invention the increase in the width of a sheet due to hygroscopic expansion is compensated by slightly raising the central longitudinal portion of the sheet above the level of the supporting feed tapes so as to draw in the side edges of the sheet a certain amotmt, sufficient to restore the original distance between said side edges.

Referring more particularly to Fig. 3, in which 23 designates a paper sheet discharged by the first impression cylinder onto the delivery platform, it will be seen that said sheet is raised at 24 along its central longitudinal line by means of a supporting device, the upper surface of which is at a somewhat higher level than that 'of the feed tapes, so that the paper sheet acquires a slant from the center towards each side.

Due to this arrangement the distance between the side edges 25, 26 of the sheet is naturally somewhat less than if'the sheet were allowed to remain in a flat condition, so that by adjusting the height of the central supporting device it is possible to draw in the side edges more or less as conditions may demand.

In the preferred form of our invention the supporting element for the central longitudinal portion of the sheet is inthe form of a tape 21 extending between a front arm 28 and a rear arm 28, said arms being adjustable in a vertical plane so as to raise more or less the front and rear ends of said tape.

The front arm 28 forms part of what we call the front unit of our device, said front unit being generally designated by the-letter A, and rear arm 28 forms part of the rear unit B, which is mounted in a board 38, said board being placed in position on the delivery platform by removing the central longitudinal bar between feed tapes l4, I5, and setting it in its place.

As stated, arms 28, 23 may be raised or lowered at will so as to accordingly raise or lower the front and rear ends of the tape 21, and the operation of said arms 28, 28 may be effected from a point external to the press where the control unit 0 is located.

As Fig. 1 clearly shows, said control unit consists of a bracket or support 31 having two laterally spaced hubs 32, 33, in which are rotatably mounted control knobs 34, 35. Said knobs are connected by a flexible shaft to the operating the device illustrated in Figs. 1 and 2 are shown in greater detail in Figs. 4 to 6 for the front unit and Figs. 7 to 9 for the rear unit.

Referring to Figs. 4 to 6', it will be seen that each front end support 21 is in the form of a clamp adapted to be fixed along round bar 22 by means of a clamping screw 4i, saidv clamp having a tongue-like extension 42 directed towards the next impression cylinder. The front unit is mounted upon the tongue-like extension of the support or clamp 2| located in proximity of the central longitudinal line of the delivery platform. The unit comprises a main body 43 which is formed with a longitudinal opening, 'the width of which corresponds to the width of extension 42, so that main body 43 can be mounted onto the extreme end of extension 42 by inserting said end within said opening and clamping said main body firmly in position by means of two set screws 44, 45. y

In said main body 43 is rotatably mounted a transversal shaft 46, carrying at one end a worm wheel 41 and at the other end a flnger 48 radially extending therefrom.

At the side of body 43 against which radial finger 48 extends is pivotally mounted at 49 a longitudinally extending lug 58 carrying the frontwardly extending thin narrow plate 28. Pivot 48 is frontwardly spaced with respect to shaft 46 so that lug 50, rearwardly extending from said pivot 46, by virtue of its own weight tends to bear against the outer end of finger 48, as Fig. 6 clearly shows. I

The front end of tape 21, which is preferably made of strip steel, is bent to form a hook 52 adapted to engage the outer end of plate 28, so that if a tension is exerted upon tape 21 and shaft 46 is rotated so as to move finger 48 to a lower position, plate 28 will be tilted upwardly to an inclined position, such as shown at 28' in Fig. 5', to whatever extent is permitted by the quantity by which finger 48 has beenlowere'd.

The operation of worm wheel 41 ,is effected by means of a worm 53, carried by a flexible shaft 54 housed within a flexible casing 36, said worm being rotatably mounted between two lugs 55, 56,

outwardly projecting from the surfaceof main body 43.

As previously explained, the flexible shaft 54 together with its casing 36 extend to a convenient point, of control where the shaft is connected to knob 34.

The rear unit consists of a longitudinal boxor casing 51, attached to the underside of board 311,

which board has a through opening 58 in correspondence -of said box or casing. Said box-or casing is formed with a longitudinal chamber" 5e,

mounted a roller 40, which'as previously stated acts as a means for deflecting downwardly the rear end 39 of tape 21.'

Flexible shaft 61 and its casing 31 extend, as

stated. to a suitable remotepoint of control where shaft 61 is actuated bymeans of ia knob 35 to.

causeany desired; angular displacement of arm 29 so as to raise the lower roller 62 any desired amount. i

Tape 21 the front end of which, as stated, is hooked over the front end of plate 28 extends rearwardly therefrom to roller 62 by which it is also supported, and then continues towards defleeting roller 40 by means of which it is deflected downwardly. Y

It is, therefore, obvious that by operating knob so as to lower finger 48 any desired amount,

arm 28 wil l be enabled to respond to the tensional force exerted upon tape 21 by weight 38', so that .plate 28 will acquire an upwardly inclined position as shown at 28 in Fig. 5 and the front end of tape 21 will be raised a corresponding amount.

Similarly, by proper operation of knob-35 arm 29 may be angularly displaced so as to raise roller 62 and with it the rear end of tape 21 the proper amount required for .compensating the hygro scopic expansion of a paper sheet at the rear end thereof.

By virtue of the arrangement described it is possible to very gradually adjust the inclination of arms 28, 29, independently of each other, so that the-central longitudinal portion of the paper sheet may be raised more at the front than at the rear or vice versa, according to the compensating action required, without disturbing the normal operation of the press. The necessary adjustments can be quickly effected in a positive manner, so as to set the tape 21 in a permanently adjusted position which may be found by testing a few sheets in succession until the correct juxtaposition of the printing impressions has been realized, Once the correct position of "the tape 21 has been found, normal printing" operations,

may be conducted on the entire run of sheets to be printed with a certainty of obtaining uniform and satisfactory results. 1

The fact that the sheet of paper is presented to the grippers serving the impression cylinder while it is slightly sloping from the center towards the sides and, therefore, not in a perfectly fiat condition, would lead one to assume that in passing through the cylinders the sheet might become slightly wrinkled. In practice, however, such is not the case because while the printing operationtakes place the sheet is held firmly by the grippers and the width compensation differential between adjoining grippers in the row is so small that neither the printing nor the paper itself are affected by the condition thereby created.

For instance, assuming that a sheet originally four feet wide has become one-eighth of an inch wider due to hygroscopic absorption and that the vertical displacement of the tape 21,

a or othenequivalent, element which may, be used for perforrhihgtthe same function.

For, instance, .in the device illustrated the meansforraising arm 28 above its normal level is constitutedby the weight 38 exerting a pull on tape 21, finger 48 tending to oppose the move- I ment of said arm 28 in an upward direction. It can easily be seen, however, that arm28 could be positively operated with equal ease by flexible shaft 54, as is done in the case of arm 29.

The drawings should,therefore, be understood as being intended for illustrative purposes only and not in a limiting sense.

We, accordingly. reserve the right to carry'our invention i'ntopractice in all those ways and manners which may enter, fairly, into the scope of the appended claims.

we claim: m 1 In a. printing press the combination, with an impression cylinder served by a set'of grippers, and longitudinally movable means for delivering a paper sheet to a position where said grippers will grip the front edge thereof, of a longitudinally directed flexible strip adapted to underlie the central longitudinal portion of said sheet, a member adjustable in a vertical plane engaging one end of said strip, another member adjustable in a vertical plane supporting said strip in proximity of its other end, the latter end being deflected downwardly, a weight attached to said latter end maintaining said strip under tension, and means for controlling said adjustable members to more or less raise said strip above the normal level of said longitudinally movable means.

2. In a printing press the combination, with an impression cylinder served by a set of grippers, and longitudinally movable means for delivering a paper sheet to a position where said grippers will grip the front edge thereof, of a longitudinally directed flexible strip adapted to underline the central longitudinal portion of said sheet, a pivotally mounted arm movable in a vertical plane, underlying and engaging the front end of said strip, a pivotally mounted arm movable in a vertical plane underlying and supporting said strip at the rear, the rear end of said strip being deflected downwardly, a weight attached to said rear end maintaining said strip under tension, and means controllable from a remote point for controlling said arms to more or less raise said strip above the normal level of said longitudinally movable means.

3. In a printing press the combination, with an impression cylinder served bya set of grippers, and longitudinally movable means for delivering a paper sheet to a position where said grippers will grip the front edge thereof, of a longitudinally directed flexible strip adapted to underlie the central longitudinal portion of said sheet, a pivotally mounted arm movable in a vertical plane, underlying and engaging the front end of said strip, a rotatably mounted finger tending to oppose the movement of said arm in an upward direction, a worm wheel in a fixed relation to said finger, a pivotally mounted arm movable in a vertical plane underlying and supporting said strip at the rear, the rear end of said strip being deflected downwardly, a weight attached to said rear end maintaining said strip under tension, a worm wheel in fixed relation to the latter arm, a worm in mesh with each worm wheel, a flexible shaft connected to and extending from each worm, and manually operable means for rotating each shaft.

4. In a printing press the combination, with an impression cylinder served by a set of grippers, and longitudinally movable means for delivering a paper sheet to a position where said grippers will grip the front edge thereof, of a lorgitudinally directed flexible strip adapted to underlie the central longitudinal portion of said sheet, a member adjustable in a vertical plane engaging one end of said strip, another member adjustable in a vertical plane supporting said strip in proximity of its other end, means tor maintaining said strip under tension, and means for controlling said adjustable members to more or less raise said strip above the normal level oi said longitudinally movable means.

5. In a printing press the combination, with an impression cylinder served by a set oi! grippers, and longitudinally movable means for delivering a paper sheet to a position where said grippers will grip theiront edge thereof, oi a longitudinally directed flexible strip adapted to underlie the central longitudinal portion of said sheet, a pivotally mounted arm movable in-a vertical plane, underlying and engaging the front 'end of said strip, a pivotally mounted arm movable in a vertical plane underlying and supporting said strip at the rear, the rear end of said strip being deflected downwardly, means for maintaining said strip under tension,;and means controllable from a remote point for controlling said arms to more or less raise said strip above the normal level oi. said longitudinally movable means.

6. In a printing press the combination, with an impression cylinder served by a set of grippers, and longitudinally movable means for delivering a paper sheet to a position where said grippers will grip the front edge thereof, of a longitudinally directed flexible strip adapted to underlie the central longitudinally portion or said sheet, a member adjustable in a vertical plane engaging one end of said strip, another member adjustable in a vertical plane supporting said strip in proximity of its other end, means ior maintaining said strip under tension, and a flexible shaft controlling each adjustable member independently of the other to more or less raise said strip above the normal level of said longitudinally movable means.

THEODORE HAKARIUS. JAMES VERZERA.

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