US2011650A - Process for cooling photomechanical printing plates - Google Patents

Description

Aug, 20, 1935. J F. T. POWERS 2,011,650,

PROCESS FOR COOLING PHOTOMECHANICAL PRINTING PLATES Filed Nov. 13, 1951 2 Sheets-Sheet 1 ok C. I

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yug.'2(`),.11!-)35. 1 F. T. POWERS 2,011,650

Y PROCESS FOR C OOLNG PHOTOMECHANICAL PRINTING PLATES 'Filed Nov. 13, 1931 l 2 sheets-sneu 2 m v INVEN-ro Patented Aug. 20, 1935 naar;

ArENr oEEieE PROCESS FOR COOLING PHOTOMECHANI- CAL `PRINTINGPILATESY -Y Frank T. `Powers, Douglaston, NQ Y. Application November 13, i931, serial No. 574,737

` l 1 claim.

invention relates't'o the art of making print-` ingplates by photomechanical processes, and par- 'ticularly'to an'apparatus for cooling the plates after they have been heated to set or fuse the powdered resist usually applied between bites.

The object of my invention is to provide a means for cooling heated printingplates from l the back `by the application oi water without or wet roller for cooling, since the warped plate danger of ever getting water on the front or printing side of theplate and to do so while the plate is travelling continuously through an automatic machine without being touched `or handled.

" Other objects and `advantages of the invention will be set forth in part hereinafter and in part will be obvious herefrom, or may be learned by practice with the invention, the same being realized and attaine'dby means of the instrumentalities and combinations pointed out in the appended claim.

The cooling of photo-engraved or linecut print--` ing plates by automatic means has presented one ofthe most difficult problems in the creation of an entirely automatic powdering machine, capable 'of `handlingall types of plates, including half tones, line work, Ben-Day or ink-top, either on copper `or zinc, or" either standard thickness of 16 gauge or the eXtra heavy 14 gauge metal. l YAbility to `successfully meet all these conditions imposes many limitations upon the cooling apparatus. While the plate is hot, nothing may touch its top surface, since Ben-Day`ink is soft andsticky when hot.v The plates often become warpedwhile being heated and so cannotbe cooled bybeing `passed over a flat `rwet surface will not' come into contact throughout its entire areawithout bringing pressure to bear on its upper surfacev to depress the upwardly warped v powdering, which immediately follows Vthe first bite4 The cooling apparatus must, therefore, hai/"e4 suflicient cooling capacity to cool such a platefrom'a temperature of approximately 500 deg. F.'down to such a temperature that it may be held in the hands of the operator without dis-` comfort. It must cool every square inch of the surface of a plate whichhas become warped and i curved while heating,.and nol water may touch the top'of the platenor may any pressure be (o1. rsa-12) f l brought to bear on the top while the plate is hot. To meet all of these conditions I have invented anapparatus of which the following is a complete description, which, taken in conjunction with the drawingawill enable one skilled in the art to make and use it. 'I'he embodiment of my invention shown in the drawings is `one which I prefer, but I do not wish to be understood as limiting my invention to this particular form since there are many variationswhichare suitable for reducing my invention to practice.`

In the drawings, like symbols indicate the same or similar parts and arrows indicate the direction of motion or of rotation. i

Fig. 1 is a side elevation, partly in sectionof my new apparatus. Fig. 2 is a plan View, Fig. 3 is avertical section on the line a-a, and Fig. 4

'is a vertical sectionyon the line b-'bof Fig.` 1.

the otherpair being located at the opposite en'd i of the `apparatus not included in the drawings. Attached to the chains, I, are a `plurality of` pusher bars; 3,' to each of which attached a shield, 4,' of special form as will be hereinafter described.- The pusher bars, 3, ride on and are supported by a series of grid bars, 5, running lengthwise of the apparatus; These grid bars are so spaced that platescut to alstandard series of dimensions will slightly overlap the grid bars upon which it rests when properlycentered thereon by the automatic plate centeringv device, described hereinafter.v .The standard series of sizes begins withplates 8 inches square andadvanced by increments of two inches in each dimension up to fourteen inches for smaller plates `and from eighteen inches to twenty-two inches for `larger plates. l w

Immediately below the grid bars is provided a series of pipes, 6, extending transversely` ofthe grid bars and terminating at each end in longitudinal header pipes, 1. Each of the transverse pipes, E, is provided with a plurality of short tubular nozzles, 8, each located midway between they adjacent grid bars, 5. At approximately the mid points of the header pipes, 1, are connected pipes, 9, which are brought together to join a common pipe, I`,` provided, with a'check valve I I, and connected with the discharge outlet of the pump, I2, driven by the motor,` I3. I Under the series of pipes, 6, is suitably supported a pan, lli, to the is an' arm, IQfcarrying'a roller, 2|), which at each having its fulcrum pin at 22. The lever, 2l, en'f` gages the slide bar, 23, which slides in the guides,

24,' against the tension of thejspring, 25. At-

tachedjto the fslide rbar, 23, is :a clamp, "26, which serves as "a Vconnecting jmember between the slide .bar 23, and the connecting rod, 21, whichlengages,y

the lower arm, 28, of an oiset bell crank Whichoscillates inthe sleeve bearing, 29. 'The upper armpj-` thelzytop."`

36], of the bell crank is pivotally connected to-fone l endvof a rod 3|, the other'end of which is con- L dof thelieatk during kthe burning in process which ,j provided with three wheels, 33, i34andr'x,which travel on suitable tracks, 3t`v and 3,7. Loo'sely` pivoted to the verticall leg of the angleiron 38 nected to a triangular travelling?,V carriage, 352',

formingone 'side Yof v`theirame ofthe triangular carriage,v 32, area plurality ofngers, `39, which ee:tonoscillate-abouttheir pivots, but which, ason Aof` the greater weight of .the portion 'Y zthe `1pivots tend ito rernairrfinla'. .verticalposition.'l

j Suitable .meansy not shown*y in the .drawings lare providedffor driving the -.chains, rl and vsuitable framework andfsupports notbshown in 'complete detailinthedrawings are .provided tosupportand rmly holdall parts'ofthe apparatus,

" Inause'theyapparatusfunctions-asfollows; l

pump isgput into operationr after making sure sulicient water ifs-.present .in rthe tank. The headofwater fin the tank, A6, may bevaried by Inaintaining vthe .-level of -the water at `vthe desired point;r which isV reflected in the height to which theiwater nozzles 8 discharge the -jets of water, Ba;

The higher the water level r5in 4the tank, lli, the higher'thegnozzles will discharge;l The top-of the trajectory of -thej water yshould'bemaintained at aboutll/z inch abovefthe tops Aofthe fgrid bars,5,'

' upon :which Ithe plateis-pushed by the bars,-ll'.v -If l 4the ltop'df .the front'for fadvancing edge. Ef the the trajectoryof ythe water jets Lis'rnaintaiined at v 5 thisfiheight the plate maybe warp'edorhentas vmuch as ehalf an inch-and stillheproperly cooled while `passing throughthejets.` llhe speed-of the.

their'v trajectory the front edge of l.the fplate will tendft'o'cut lthrough the jets .and Iwaterjwill reach water is travelling forward faster than ther plate,

thereiwillrbaa tendency. for :the water tozbefthrown up ion the rear redge of the `rplate and so wetr the I. top '.-lThisfisfarr-important condition to maintain lin 'ioonnectionjwith the Operation 4'of V'the cooler; andis oneiof" the'essenti'al :elements -of its success Land:eiciency; The flowrofathe water fromthe iets havingl been properly adjusted, thehot plate to fbeloooled is placed onthe cooler at the point C on the .reeeiving'ftable 40, and -Wh'en 'Y one of lthe pusher bars f3-Illas justfpas'sed 'underithefedge -of thefreceivingtablelthe"plateis pushed oif the edge of the 1receiving table, f, and dropson the grid =bars .E'fju'stinffrontfof thernextadvancingpusher bar3.

A13-this!,instant the roller r2l) vori-arm vL9 contacts pimjtne-1everg2r twhich pushesthe slide-bar 2s andren bymeansfof thelrod Z'Land the hellcrank unit,`28,`29`"and 3l), the carriage 32 is movedover andthe 4lingers `Si] .push the `plate ,intocorrect positionvrrelative to r. thegridfbars 5.l This correctr position lis indicatedinlig .4 which shows the plate .D restingion ,thegridharsbf y.with each, side of the plate slightly overhanging a grid bar. In this position the jets of water, which are located midway between the grid bars 5'do not impinge cover a known number of gridloars 'If a water jet Yis permitted to impinge directly on one of the 'ide edges of a plate, the water may carry over or follow aroundtheedge of the plate and so wet j If the plate is Warped or curled by the actionk f Airrirnediately precedes :this cooling process in the making of printing plates, it will not lie flat upon thef'grid Ibarsrand in contact therewith. vThis fact, however, will not interferewith,tshecoming .cooled `by Vthe iznpi'ngernent!r of j thepcool water fromthejets againstA its .11,1fnder`side, by reasonof the height abovefthe topof the grid barstowhich the water in ythese jets'i's projected. Thisffact strongly` .differentiates this ymethod of coolingplat-eslfrom. all .other methods heretofore in use, inwhich itis necessary `that `the plate eitherhe flater nearly so Ainorcler to .come .in .contact with the cooling medium,` Yor else that the vcurved-0r warped-.platebe pressed-against the cooling me` dium 'by v'pressure applied yto fthegltop orprinting side of the plate,-anoperation not permissible with plates having anr ink top, rvsuch, .for yeX- ample, as plates prepared `by the Ben-Day ,process. -v 'Y The plate having `been centered on the grid bars, `thelpusher bar, A, pushes the plate along ythe top of the `grid bars and Vinto and through the numerous water jets, each of whichcontinuonslyy playsfa stream of waterl against the under side I.ofthe plate, quickly .reducing the `temperature of the ,-platelto a point lwhere it is easily lhandled .without discomfort -by the operator. The plate vhaving been pushed ythrough :thecooling `zone .is vdelivered tothe point E Where it is removed by vthe operator, or Aif .the cooling ldevice forms lan integral .partiof an :apparatus by which other than the `cooling operation is performed, thejplate is Ipassed on to fthe succeeding step lin the operation by y*thefpusher"barw't' t I arri-aware that :cooling devices involving the use of ya plurality of'jetstof water impingingupon the object vto belcooledhave been-inuse for a variety ofv fpurposes, and .'Ildo not broadly .fclaim such a device.v In gmy newcooling `device'depend rupon ya `particular arrangement Vof water jets andupon adjustment of the Yvelocity .and-dif rection of 7the ow of the'water emerging from the jets and `upon coordinating the `velocity of movement of the plate with the Vmovement offthe water inthe jets to prevent. any .of the water reaohingthe top or .printingsurface of ,the plate where considerable damage might result.

vHaving described -my vinvention and ,a .preferred ,formA of apparatus by meansVv of .which fit maybe .putto practical will now state whatll claim to be newand for` whichl pray that Let? ters .Patent be granted. v

,Iclaimvg L c .The lprocess of cooling gphotomechanical print# ing plates, comprisingprojecting a .plurality-of upwardly vinclined uniform v jets ofl water `having uniform trajectories, and conveyingvthe .plates through .said jets off-.water at .a levelzbelow the topr of their vrtrajectory, ap'proximately invfthe horizontal direction @of Atheir ilow,vata velocity substantially .equal to the horizontal ,component ofthe .velocity of flow-.of the water. i

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