US2359385A - Process of making printing plates - Google Patents

Description

oct 3, 1944' i F. E. REL-LY ETAL 2,359,385

PROCESS OF MAKING PRINTING PLATES Filed May 20, 1941 s sheetssheet 1 PR/NT/NG `SURFACE TH//v CCPPER E/ ECTRCTYPE l A (FROM EAU of? wnx Mom) (CUETER Mfg /Zkvf I ff J J v Y l. (/4 VACUUM CHUCK f l /4 l soFT MET/Ll. OVER/.AY

VACUUM CHUCK CRV/Lam MU'NIW v-RNEYS Oct- 3, 1944 F. E. REILLY x-:TAL 2,359,385

PROCESS OF MAKING PRINTING PLATES Filed May 2o, 1941 s sheets-sheet 2 RuTz-:D our TYPE MATTER Mgg TME Fu/ L To/vE r Fuu. ToNE @6' i f f7 L /W ,/Y//

3 BUFFED SURFACE ./0 ROL/TED OUT A a.; 40 @ya caFPER ELEc/forff PRINT/Nq SURFACE ATTO R N EYS 06f 3, l944 F. E. REILLY ET L 2,359,385

PROCESS OF MAKING PRNTING PLATES Filed May 20, 1941 3 Sheets-Shea?I 3 DUMMY BASE l COOL/)NT .iP/NZ E f4 F OIL.

ELECT/@TYPE LE ELE/cT/TOTYPE f [j D c, DEAD METAL UQSXg DROP/25D our ELECTAUTYPE -f DEAD MET/4L REAS REMOVED BY OUTLINE /JOL/T/Mcr` W ATTORNEYS Patented Oct. 3, 1944 PROCESS F MAKING PRINTING PLATES Frank E. Reilly, Chicago, and Chester Holsinger, River Forest, Ill., assignors to Electrographic Corporation, New York, N. Y, a corporation of Delaware Application May 20, 1941, Serial No. 394,262

9 Claims.

The present invention relates to a novel and improved process of producing printing plates, particularly curved or parti-cylindrical electrotypes, as well as the novel electrotype produced by such process.

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 attained by means of the instrumentalities and combinations pointed out in the appended claims.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements herein shown and described.

The accompanying drawings, referred to herein and constituting a part hereof, illustrate one embodiment of the invention, and together with the description, serve to explain the principles of the invention.

Of the drawings:

Figure 1 is a diagrammatic sectional view showing a thin relatively flexible electrotype in accordance with the present invention;

Figure 2 is a diagrammatic View showing the cutting operation by which the electrotype is re duced in thickness and provided with a relativel smooth back;

Figure 3 is a diagrammatic sectional View illustrating the bumping or making-ready of the electrotype in accordance with the present in- Figure 4 is a diagrammatic sectional View showing the thin electrotype with its soft metal overlay still in place;

Figure 5 is a diagrammatic sectional view showing a further cutting operation by which the back of the made-ready plate is smooth;

Figure 6 is an exaggerated diagrammatic fragmentary section of the made-ready and partially routed plate;

Figure 7 is a top plan view showing the madeready and partially routed place in accordance with the present invention;

Figure 8 shows an end view of the plate of Figure 7 bent to the general curvature desired;

Figure 9 is a back View of the plate shown in Figures '7 and 8 with low-fusing alloy foil applied to certain portions of its back;

Figure 10 is a diagrammatic sectional view taken on the line Ill-l0 of Figure 9 and showing the foil applied to certain areas of the plate back;

Figure 11 is a perspective view showing a turtle -or dummy-base for use in connection with the present invention;

(Cl. lOl-401.1)

Figure 12 is a diagrammatic sectional view showing the apparatus for mounting the thin electrotype on its curved base or turtle;

Figure 13 is a top plan view of the plate secured to its turtle or base, and with the routing completed for removal of the dead metal or nonprinting areas; and

Figure 14 is a sectional view taken on the line l4-I4 of Figure 13 and showing the plate secured to its turtle and with the dead metal areas dropped out.

The present invention has for its object the provision of a novel and improved printing plate particularly adapted for use in color printing, as well as the provision of a novel and improved process for the production of curved electrotypes for high quality letterpress printing, particularly in multicolor. A further object of the invention is the provision of a novel and improved electrotype which has exceptional wearing qualities, which can be prepared for printing prior to being placed on the cylinders of the printing press, and which has relatively little stretch from the time it is removed from the electrotyping case until it is completely prepared for printing on the press. The invention also provides a novel and improved process of preparing curved electrotypes in which the plate as it is mounted on the press has substantially the same dimensions as the original photoengraving from which it was made, thereby simplifying and rendering more accurate the register of four color process plates.

Still another object of the invention is the provision of a novel and improved electrotype vwhich does not require underlays or overlays during printing, and in which the register of the several electrotypes is accurately predetermined prior to the plating of the press, thereby reducing the time required for the plating of the press.

Heretofore, in the printing of curved electrotypes it has almost universally been the custom vto prepare the electrotypes in flat form, to remove the electrotype shell from the case, to back the electrotype shell with lead or other alloy and then to shave or otherwise surface the back of the shell and alloy, after which the llat surfaced and backed electrotype shell is bent to the desired curvature so that it will accommodate itself to the surface of the printing cylinder to which it is to be clamped.

This usual process requires a great amount of care and a high degree of skill, inasmuch as the `plate stretches unequally during the bending operation, the solid printing areas stretching differently from the dead or non-printing areas,

and the copper shell stretching differently from the dead or non-printing areas, and the copper shell stretching differently from the lead or alloy backing. Inasmuch as a set of multicolor plates are necessarily different from each other, this amount of stretch is different for each of the several plates of each set, and it is only with the greatest exercise of care and skill that commercially satisfactory register is obtained between the plates. Furthermore, the printing surface is frequently damaged during the bending operation, and even where make-ready is incorporated in the plates, as by bumping or by the McKee process, the electrotype is still relatively soft due to the large thickness of lead or alloy with which it is backed, and the printing characteristics of the plate change during a long press run.

Another disadvantage which has heretofore existed in connection with the use of curved electrotypes, is theA fact that frequently the curvature of the electrotype is not exactly uniform nor is it exactly the same as the curvature of the printing cylinder on which it is to be mounted with the result that the plate must be warped as it is clamped to the cylinder and the plate may rock very slightly during the printing operation. The back of the plate, being of lead or other alloy, has relatively little strength, and is readily subject to crystallization, so that frequently during the printing operation the plates are thrown from the printing cylinder creating a hazard for the workman as well as being capable of causing serious damage to the printing mechanism.

All of the foregoing and other disadvantages are avoided by the process and plate of the present invention. In accordance with the process of the present invention, an electrotype mold is prepared in a conventional manner from whatever type, photoengravings or other matter is to `be reproduced. This mold is electro-deposited in the usual electrotyping manner until the mold has been coated substantially uniformlyV to a thickness slightly in excess of 0.045 inch. When this electrotyping operation has been completed, the electrotype l is stripped from the mold and is placed on a rigid flat vacuum chuck I4, where it is held by suction while the black is milled by cutter I2, or otherwise cut and smoothed, to reduce the thickness ,of the plate to between approximately 0.020 and 0.0401116111.

This` surfaced, relatively thin electrotype is then provided with a registering underlay I8 of conventional form attached to its back and is placed fa-ce up on the platen I6 of a hydraulic press, after which the face of the electrotype is covered with a thin sheet of relatively soft metal over which is laid a relatively thick layer of resilient packing 22 such as a large number of sheets of newsprint. The ram 24 of the hydraulic press is then lowered and powerful pressure is applied to the assembled electrotype, underlay, overlay and packing, conforming the electrotype to the underlay and embossing the soft metal overlay.

When this operation lhas been completed, the thin electrotype and its soft metal overlay are removed from the hydraulic press and are placed on a cutting or surfacing apparatus where the plate and its soft metal overlay are placed on the vacuum chuck I4, with the overlay 20 beneath the plate I0 and between the plate I0 and the surface of the chuck I4. The plate is then given a finishing cut by means of the fine cutter 26 on its back so as to render the back smooth and to remove any inequalities caused by the hydraulic pressing operation, as well as to remove the roughness left by the rst cutting operation.

When the plate has been thus made ready, the

edges of the plate l0 are accurately trimmed to the desired size, the soft metal overlay 20 is removed from the printing face, and While the plate is still flat, the small areas 3B which are not to print are carefully routed, such as the spaces between the columns as well as the spaces between some of the larger letters. Thereafter the plate I is bent, manually or otherwise, so as to conform it to the general curvature required, and due to its extreme thinness this can easily be accomplished.

We have found by actual experience that the bending of a plate which is 0.040 inch in thickness and is to be tted to a cylinder having four plates around, does not stretch more than approximately 0.015 inch, which is an insignificant amount, and differences in the stretch of various plates amount to only a few thousandths of an inch, so that commercially perfect register is uniformly obtained.

The partially routed, preliminary bent thin electrotype which has been made ready is then placed with its face down and its smooth back is coated with soldering flux, after which the back of the plate is covered with an exceedingly thin sheet 4| of a low fusing alloy foil over substantially its entire surface, excepting only any relatively large dead or non-printing areas 39.

In routing the dead areas 39, they are preferably left attached to the main portions of the plate by means of joiners until after the plate has been soldered to its base 49, after which these dead areas 39 may be removed by routing or cutting through these joiners thereby detaching the dead areas from the remainder of the plate.

The plate thus prepared for soldering is then accurately registered with respect to its turtle or dummy base 49, which is a smooth accurately machined parti-cylindrical member, and usually of the same size as the thin electrotype, is of considerable thickness so as to be quite rigid, and is preferably formed of some dense, strong material which can be soldered and re-used, such as brass or bronze. The thickness of the turtle 49 is such that combined with the plate l0 to be attached to it, they will be of proper thickness for the rotary press on which they are to be printed. The plate and its turtle which has been previously fluxed, are then placed in a mounting apparatus which comprises a concave member 50 conforming in curvature to the desired curvature of the finished plates and a convex member 5| of the same curvature as the printing cylinder. While the plate I0 and its turtle 49 are securely clamped between the concave and convex members 50 and 5I, the plate and turtle are heated by gas flames 52 slightly above the melting point of the solder foil 4I, and are then cooled by water or other cooling medium to set the solder, after which they are removed from the mounting apparatus with the plate securely fastened to its turtle in a definite predetermined position, insuring accurate register.

If the plate contains any dead metal or relatively large non-printing areas, such as 39, the plate and its turtle are placed on a curved routing machine, these dead metal areas 39 are outlined in the router, the router cutting entirely -through the plate so that the dead metal areas drop out on removal of the plate from the IOuting machine.

Thus, there is produced a novel and improved 'electrotype which is of substantially the same dimensions as the original from which it was made, Vthe electrotype and its back are relatively dense, and there is no appreciable thickness of soft metal which can yield during the printing operation, the makeready necessary for proper printing is accurately incorporated into the plate itself, and the assembled plate and turtle are completely ready to go on the press with the assurance that the mere clamping of the turtlemounted plate in a predetermined position on the printing cylinder will result in accurate register, thereby eliminating most make-ready and -registering operations of the press, with result- .ant saving in press time.

The foregoing general description is the preferred process of carrying out the present invention, but certain of the steps may be modied or omitted without impairing the usefulness of the Vprocess as a whole, and with a consequent partial achievement of the various benefits of the present invention.

Referring now in detail to certain Iof the steps -of the present invention, the lead or wax mold from which the electrotypes are to be produced,

may, if desired, be given a preliminary flash coat or electrolytic deposit of nickel if steel-faced `electrotypes are desired, and thereafter the cop- -per electrotype is deposited on the mold.

While various electrotyping baths may be used,

We find it advisable to control the rate of deposit,

and the composition of the bath, in known manners so as to produce a relatively dense, hard,

vlong wearing copper deposit of relatively great strength which is preferably from 0.020`to 0.045 inch in thickness. In certain instances it is possible to use even thinner deposits, but generally they do not provide suilicient strength, while in .other instances it may be possible to use thicker deposits but the thicker the deposit the greater the stretch of the plate during the curving operation.

During the first cutting operation, the thin .eleetrotype I is placed with its face down against the vacuum chuck I4, and the-cutter I2 and chuck I4 are moved relatively to each other at a relatively slow speed While the plate is securely held to the chuck by vacuum. In order to improve the security of the holding, the plate is preferably formed with a -continuous bearer com- .pletely outlining the printing portion of the plate, .thereby providing a uniform flat surface which will accurately seat against the chuck and prevent leakage of air beneath the plate.

The underlay I8 utilized, in case it is desired `to incorporate the make-ready into the plate, kalthough it is not essential, may be either en..

gravers underlay, or a press underlay, and is of vvarying thickness, the thicker portions lying immediately under the parts of the plate which are Ito print the most ink. Thus, in an illustration,

the full tones might be underlaid with paper of the thickness of 0.004, the half tones with an underlay having the thickness of 0.002", and

the highlights might have all the underlay omit- 4ted. The soft metal overlay 20 provided 0n the sheets of newsprint, the soft metal overlay 20 being ofapproximately the same size as the thin .copper electrotype, while the resilient packing I8 is of slightly larger area.

During the finishing cutting operations, where the back of the plate is milled or otherwise surfaced to remove the portions of the back of the plate raised during the makeready on the hydraulic press, the cutter 26 preferably travels diagonally of the plate l0, the cutting operation being carried out with the soft metal overlay 20 still adheringto the face of the plate, preferably without having been removed therefrom.

Figures 6 and 7 of the drawings show the thin electrotype after it has been made ready, finally surfaced on its back, and partially routed, and in these figures the thin electrotype I0 is shown as provided with a ilat, smooth back 30, with type matter 3| on its face, and withvarious halftone parts also on its face. The half-tones of the illustrations are shown at 33 andare raised sightly above the level of the type matter so as to exert somewhat more pressure during the printing operation, while the full tones 34 are raised even more to exert still greater pressure. The yhighlights 35 in the illustrations may be the same height as the type matter, or otherwise as determined by the underlay employed. At certain places, such as 38, some of the smaller non-printing areas of the plate have been routed out, while other large non-printing areas 39 are later cut apart so that the metal may be completely removed.

In order to facilitate accurate register, the plate is conveniently provided with conventional register marks 40, incorporated inthe plate from which the electrotype was reproduced, these register marks Ibeing accurately located with respect to each other. The plate is trimmed, to remove the bearers, and this trimming is carried out carefully so that the edges of the plate have a predetermined relation to the register marks, and accurately correspond with the dimensions of the turtle, thereby enabling the plate to be placed on the turtle, its edges registered with the edges of the turtle, thereby insuring ,accurate register of the several plates on their respective turtles.

In case greater accuracy in register is required, the plate lll may be provided at its ends with relatively small drilled holes 42 which are accurately spaced with reference to the register marks 40, and are so spaced with respect to each other and the printing surface that they correspond exactly to similar holes 46 formed in the-turtle, thereby enabling the plate to be accurately positioned on the turtle during the sweating or soldering operation by means of locating pins 41.

Any suitable or desired flux may be employed for the back of the plate I0 and the face of the Vturtle 49, but preferably the flux is a completely volatile type so that no solid residue remains Which might show through or deforrn the relatively exible thin electrotype. Preferably, the sheet of low fusing alloy foil is less than 0.001 inch thickness, and may conveniently vbe of equal parts of tin and lead. This sheet of solder foil 4| is placed over the entire back of the plate I0, excepting only those parts corresponding to dead metal or non-printing areas 39 which are not to be soldered to the base.

The turtle or dummy -base 49 comprises an ar- ;cuate vor parti-cylindrical member, accurately corresponding to the surfacepf the printing cylinder and may -be formed with slightly beveled edges by which it may be gripped by the plate securing clamp on the printing cylinder. Near its ends, the base 49 is provided with holes 46 to receive registering dowel pins 41 which also pass through holes 42 in the plate l0 and accurately register the plate or its base during soldering.

The plate I is accurately registered on its base 49 and the two are then placed in the saddle 50, pressure is applied by the convex member I and the plate is heated just above the melting point of the solder Aby means of the heaters 52 thereby sweating the plate ID to its base, after which cooling water is iiowed through pipes 54 and back 5| to set the solder quickly.

The dead metal areas 39 may then be outlined by routing and when this has been completed, the dead metal drops out leaving the base 49 visible and increasing the depth of the areas.

Certain features of the invention are useful in connection With the production of flat printing plates, for instance, Where a made-ready electrotype formed of dense metal is required for printing.

The invention in its broader aspects is not limited to the specic mechanisms shown and described but departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacricing its chief advantages.

What we claim is:

1. A process of producing a curved printing plate which comprises cutting the back of a thick electro-deposited plate to reduce its thickness and provide a smooth, flat back, routing the at plate, applying thin solder foil to the back of the plate, forming register holes in the margins of the plate, applying the plate to a thick curved base having similar register holes, heating the plate to solder the plate to the base, and lcutting around dead metal areas to drop out the dead metal from the Icompleted plate.

2. A process of producing a curved printing plate which comprises cutting the back of a thick electro-deposited plate to reduce its thickness and provide a smooth, flat back, providing said plate with an underlay and a soft metal overlay, powerfully pressing said plate between the underlay and overlay to raise the heavier printing portions of the plate, again cutting the back of the plate with its overlay in place to smooth the back of the plate, routing the flat plate, applying thin solder foil to the back of the plate, applying the plate to a thick curved base, heating the plate to solder the plate to the base; and cutting around dead metal areas to drop out the dead metal from the Icompleted plate.

3. A process of producing a curved printing plate which comprises cutting the back of a thick electro-deposited plate to reduce its thickness and provide a smooth, fiat back, routing the flat plate, applying thin solder foil to the back of the plate, applying the plate to a thick curved base, heating the plate to solder the plate to the base, and cutting around dead metal areas to drop out the dead metal from the completed plate.

4. A process of Iproducing a curved printing plate which comprises [cutting the back of a thick electro-deposited plate to reduce its thickness and provide a smooth, flat back, providing said plate with an underlay and a soft metal overlay, powerfullypressing said plate between the underlay and overlay to raise the heavier areas.

printing portions of the plate, again cutting the back of the plate with its overlay in place to smooth the back of the plate, routing the fiat plate, applying thin solder foil to the back of the lplate, forming register holes in the margins of the plate, applying the plate to a thick curved base having similar register holes, heating the plate to solder the plate to the base, and cutting around dead metal areas to drop out the dead metal from the completed plate.

5. A process of producing a printing plate which comprises cutting the back of a thick electro-deposited plate to reduce its thickness and provide a smooth, nat back, providing said plate with an underlay and a soft metal overlay, powerfully [pressing said plate between the underlay and overlay to raise the heavier printing portions of the plate, again cutting the back of the plate with its overlay in place to smooth the back of the plate, routing the fiat plate, applying thin solder foil to the back of the plate, forming register holes in the margins of the plate, applying the plate to a thick base having similar register holes, heating the plate to solder the plate to the base, and cutting around dead metal areas to drop out the dead metal from the completed plate.

6. A process of 4producing a printing plate which comprises cutting the back of a thick electro-deposited plate to reduce its thickness and provide a smooth, at back, routing the flat plate, applying thin solder foil to the back of the plate, applying the plate to a thick base, heating the plate to solder the plate to the base, and cutting around dead metal areas to drop out the dead metal from the completed plate.

7. A process of producing a printing plate which comprises cutting the back of a thick electro-deposited plate to reduce its thickness and provide a smooth, flat back, routing the flat plate,

Ywith an underlay and a soft metal overlay, powerfully pressing said plate between the underlay and overlay to raise the heavier printing portions of the plate, again cutting the back of the plate With its overlay in place to smooth the back of the plate, routing the flat plate, applying thin solder foil to the back of the plate, applying the plate to a tlrick base, heating the plate to solder the plate to the base, anad cutting around dead metal areas to drop out the dead metal from the completed plate.

9. A process of producing curved printing plates including cutting the back of an electrodeposited plate and provide a smooth, fiat back, thickness, routing said plate while it is flat, routing around dead metal areas 1in the plate but leaving joiners connecting the dead metal areas to the remainder of the plate, curving said plate, attaching it securely to a curved base member and cutting the joiners to remove the dead metal FRANK E. REILLY. CHESTER HOLSINGER.

Images