US1377515A - Rectification of printing-plates - Google Patents

Description

E. E. NQVOTNY.

HECTIFICATION OF PRINTING PLATES.

APPLICATION HLED AUG.6,'1918.

. 1,377,515 Patentd May 10,1921.

UNITED STATES PATENT OFFICE. I

EMIL E. NOVOTNY, or PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T J. STOGDELL s'roxns, or MOORESTOWN, NEW JERSEY.

nncmrrcarroiv on PRINTING-PLATES T 0 all whom it may concern:

' Be it known that I, EMIL E. Novo'rNY, a

citizen of the United States, .residing at Philadelphia in the county of Philadelphia and State of Pennsylvania, have invented new and useful Improvements" in Rectificationof Printing-Plates,of which the following is a specification.

This invention relates to the manufacture of printing plates and has particular a-pplication to the rectification of molded printing plates and such as are made from a plastic material as bakelite, condensiteor other synthetic resin. p

In carrying out my lnventlon-it is my purpose to provide a rapid and ready method ofleveli'ng printing plates and of incorporating therein the required regulari- I ties and irregularities such as are practised in the printing art and usually termed make ready. Half-tones and original type matter when assembled in a type form or chase frequently present irregularities in height, or in some instances possess conations.

caved or rounded or imperfect type faces due to wear incident to use in printing oper- Of course it is desirable that a printing plate produced from a matrix made from such a body'of type or from such printing and it is desirable to incorporate this make-ready in the molded plate'beforeit is placed on the'press. In electrctyping' it is the practice to eliminate these errors or irregularities in the plate by pounding the "back of the electrotype while its face is in contact with the levelsurface plate,'but this method of rectifyingthe plate is unsatisfactory and does not permit the attainment of accuracy in'the'cross-s'ectional thickness of 3 the platenor does it allowof the'introduction of make-ready corrections into the body of the plate.

In plasticplate making, or where print i'ng plates 'are'made by means of a moldlng I operation, it is impossible to pound out 'jirregularities as'is done with'electrotypes and it is therefore desirable to" resort toother means to secure the necessary rectifi-x plate.

.cation of theplate. In the manufacture of synthetic reslnous printing plates, such as Specification of Letters Patent. Patented lu y 10 1921 'Application filed August 6, 1918. Serial No: 248,648; i i

those made from bakelite or condensite, I

' have found that by using a body material which is not compressed beyond its elastic limit, but which may be further slightly compressed after the printing characters havebeen molded on the face of the plate, such a plate may be rectified or corrected in such a manner as to obtain uniformity in the height of the letters as well as uniformity in the cross section of the plate, and to employ make-ready in the rectification process. These necessary and desired corrections may be accomplished because of the fact that in themolding of a plastic plate under heat and pressure, the plate is subjected to a molding operation for just asuflici'ent length of time to bake a hard film or skin on each face of the plate, while the interior of theplate will remainrelatively soft when compared with the exterior surface.

heated condition and subjected to pressure between the level platens of the press so as tion ofthe plate, the interior portion yielding sufficiently without lateral flow or spread, to accommodate or compensate for the backward pressure of the hardened irregularity of the surface'sections of the In the accompanying drawings Figurel shows a crosssectio'nal view of a printing 'press'iplate composition between two platens of asuitablepress preparatory to rectifying the plateby levelingand the introduction of make-ready.

Fig. 2 is a cross sectional view of another form of printing plate which may be corrected in accordance with my method.

Flg. 3 1s a View partly, n elevation and partly in section showing a. printing plate Theresult' will be that such a plate may be placed in a press while in a tolevel the printing surface, as well as the back of theplate by forcing the uneven portions or irregularities of the hardenedskin back toward the relatively soft interior porcoated on itsprintiiig surfaces with a waxy "substance, the non-printingportions of the plate being exposed to the action of a sand blast for the purpose of deepening the same.

Referring now to the accompanying drawings indetail: The letter A indicates the lower hollow platen of the press while BY designates the upper hollow platen thereof,

7 interior portion 6 of the plate.

with these plates having steam inlets l and steam outlets 2. Upon the level face of the thereof and the upper printing face 5 are relatively harder than the intermediate or This occurs in the baking operation in molding the plate, because the outer surfaces of the plate will bake or cook until a hard shell like skin or film is formed around the plate, this synthetic resinous material being a poor conductor of heat so that the outer surface portions will bake more readily than the interior of the plate body. If it be desired to correct such a plate it may be preliminarily heated either in a separate oven, or in the press and is then placed as shown in Fig. 1 upon the lower plate, and with the bearers arranged at opposite sides of the plate to limit the closing of the platens. If it is not desired to incorporate separate make-ready in the plate the platens may be simply closed to force the back of the plate fiat against the face of the bottom platen of the press and to force such irregularities as may appear in the type surface of the plate down toward the interior of the plate, the material of the interior of the plate being displaceable, or capable of yielding sufficiently to permit of this so that the high sections of the type surface will ,be depressed or sunk to the proper level thereby enabling a plate of uniform thickness and height of type to be made.

If it be desired to form a printing face of the plate with certain regularities or irrcgularities to compensate forpress errors or for the peculiarities of a particular press, suitable negative make-ready such as is shown at 7, and which is well known in the art, may be laid or placed upon the printing surface of the plate in proper coincidence with the type sections of the plate which are to be corrected by tnis make-ready, and the platens of the press may then be closed to force the make-ready against the sub 'acent printing surface of the plate, and of course these sections will be forced or sunk toward the interior of the plate and the necessary correction thereby obtained.

In Fig. 1 it will be noted that the back of the plate C is substantially smooth'while in Fig. 2 I have shown a modified form of the plate indicatedby C and in this instance the bottom face of the plate is formed with a field or cone shaped dots, or is pitted as shown at 8, the purpose of so forming the back face of the plate being to allow for compression from the back of the plate inward toward the center thereof, aswell as toward the face of the plate, thus permitting of more leeway in the leveling and correction of the plate than can be obtained where the back of the plate is smooth in the first instance as is shown in Fig. 1. Therefore in the preparation of my printing plates I prefer, in initially making the plate, that is to say prior to its correction, to mold the plates with dots, pits or depressions in the back face thereof. Of course when make-ready is used in making the correction such make-ready is removed after the rectification of the plate has been accomplished. This method of leveling and of treating the plates with make-ready enables me to manufacture plates from type matter which is not of proper printing standards, and also permits of the leveling operation being accomplished in a simple and speedy manner at the time of incorpo- .rating the make-ready and also provides for obtaining a plate of a predetermined level and of uniform thickness. From a print ing standpoint it enables me to make a printing plate which requires no makeready when applied to the printing press and enables the pressman to obtain a maximum production from a printing machine with little or no delay in machine attention or activity.

In some instances the leveling of the plate may decrease the depth of the. nonprinting parts of the printing surface of the plate and then again on occasions itmay be desired to obtain greater depth in nonprinting parts. Under such conditions I may apply to the printing surface of the plate a greasy or waxy paste 9 composed for instance of beeswax and rosinoil, the. application of the paste being madebymeans of a printing roller or cloth swab, or any other suitable tool.

' low, non-printingparts in certain'types of printing plates.

What I claim is: 7 I I v The herein described method. of rectifying a molded printing plate madefrom a plastic substance, which consists in first molding a plate under. heat, and pressure for a suflicient length of time to obtain relatively hard, skin-like face and back portions The paste is applied onlyto the printing portions of the printing plate and provide a printing surface for the face portion, the interior portion of the plate remainin relatively soft and capable of limited displacement under subsequent pressure, and subsequently subjecting said plate while in a heated condition to pressure to force irregularities in the hard printing face inward in the body of the plate and my hand.

in opposition to the soft displaceable in-.

terior portion of such plate, and While 10 maintaining the back portion ofthe plate in a substantially flat and level condition.

In testimony whereof I have hereunto set I EMIL E.;NOVOTNY.'

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