US2101052A - Printing plate and method of mounting the same - Google Patents

Description

Dec. 7, 1937. A, B DAWS 2,101,052

PRINTING PLATE AND METHOD OF MOUNTING THE SAME Filed June 26, 193] 2 Sheets-Sheet l 14 j@ fw/ f w Leg 4 r fj Ty/.55

Dec. 7, 1937. A. B. DAVIS 2,101,052

PRINTING PLATE AND METHOD OF MOUNTING THE SAME Filed June 26, 1931 2 sheets-sheet 2 W PMAM f CM1-*w ATTORNEYS Patented Dec. 7, 1937 UNITED STATES PATENT OFFICE PRINTING PLATE AND METHOD F MOUNT- ING THE SAME Arthur B. Davis, Springfield, Ohio Application June 26, 1931, Serial No. 546,951 4 Claims. (Cl. lOl-415.1)

This invention relates to the printing of books, press equipment to be used inthe mounting of the maga-Zines and the like wherein the type is carplate assembly on the press.

rled on a plate in the form of a thin sheet or shell. A more detailed object is to provide a printing More particularly, the invention is concerned plate assembly comprising a relatively flexible with the reinforcement of electrotype shells and type-Carrying sheet stretched over and attached to 5 to the manner of mounting the same preparatory a separately formed backing member adapted for to actual printing. The present application is a adjustment in any direction along the surface of continuation in part of my prior application a printing press support.

Serial No. 270,534, filed April 16, 1928. Another o-bject is to provide in a printing plate l0 According to present practice, each electrotype assembly of the above character, a type-carrying 10 shell formed by depositing copper electrolytically Sheet possessing Sufficient eXibility O yield upon a mold taken from an original or master under the normal pressure of printing and whereform is reinforced by a heavy non-flexible lead by added printing pressure over selected areas of backing which is applied` to the back of the shell the type face may be produced by make-ready l5 in the molten state. The intense heat to which details located between the sheet and its backing. 15 the shell is thus subjected, causes objectionable Other objects and advantages of the invention distortion of the type face. Considerable time will become apparent from the following detailed and skilled labor must then be expended to work description taken in connection with the accomthe face back into its original shape with the repenying dIaWllgS, in Which slllt that the cost of the finished plate is increased Figure 1 is a fragmentary plan View 0f the Cyl- 20 materially and a true reproduction of the original inder of a printing press on which is mounted a form surface is seldom obtained. With such plate assembly embodying the features 0f the plates, complicated make-ready sheets are represent inVentiOn.

quired and the making of the press ready for Fig. 2 is an enlarged sectional view taken along printing is a tedious process, tying up the costly the line 2 2 0f Figlpress equipment for long periods of time. Fig. 3 is a rear elevational view of the plate The printing surfaces of standard lead backed assembly with a portion of the backing plate plates stretch considerably in being curved for broken away to show the detail make-ready emuse on rotary presses thereby making it imposployed.

sible to make cut overlays from the master form. Fig. 4 is a fragmentary sectional view of one 30 With some designs, the printing surface becomes side portion of the plate assembly on a still larger distorted to such a degree in bending that it will scale than Fig. 2.

wear off rapidly in the press. Fig. 5 is a fragmentary view similar to Fig. 4 The above characteristics of standard electroillustrating a modication of the present invenplates are particularly objectionable in process or tion. 35 multi-color printing owing to the necessity for Fig. 6 is a fragmentary view similar to Fig. 1 exact register between the different color plates showing a further modication of the invention. which become distorted differently in the appli- Fig. 7 is a section taken along the line 1 1 of cation of the lead and ln bending. It is virtually Fig. 6.

impossible to match the color of the original ow- Fig. 8 is a sectional view similar to Fig. 7 40 ing to the fact that the so called dots producing taken through the opposite end of the plate the different half-tone effects are distorted mateassembly.

rially in working the lead backed shell into shape. In the exemplary form of the invention shown One object of the present invention is to overin the drawings. 5 indicates a thin sheet metal 45 Come the abOVe Objections by DTOViding a new shell commonly known as an electrotype having and improved printing plate assembly whCh Del'- type 4 corresponding to the characters and other mits of a method of manufacture avoiding distorconfigurations of the page to be printed standing tion of the type surface; which reduces the cost out in relief on one side of the shell and presentof and the time required for the manufacture of ing faces which contact the paper during print- 50 the plate assembly; which simplifies and faciliing. Cavities corresponding to such type indent tates the preparation of detail make-readies bethe other or back side of the shell so that at all fore going to the press, and may, in some inpoints the metal of the shell is of substantially stances, eliminate the use of such make-readies; uniform thickness usually from .015 to .020 of an and which at the same time enables standard inch. Narrow marginal edge portions 6 integral 55 with the rectangular type-carrying portion. are formed along each side edge of the shell.

In accordance with the present invention, the type cavities are completely lled with material 1 which suiciently hard and strong to reinforce the type against collapse under the pressure encountered in use on a press, which will adhere well to the metal of the shell without the application of a distorting heat, and yet possesses a substantial degree of flexibility without danger of cracking. In so far as the reinforcement of the type is concerned, it is merely necessary to fill the cavities, but to facilitate the formation of a smooth back surface disposed exactly parallel to the type face of the shell, it is preferred to coat the entire under surface of the shell and thereby form a continuous layer 'la of a thickness, when finished, approximately equal to that of the shell.

Various materials may be used for filling the type cavities and the present invention is not limited to the use of any particular material. I have found that a non-metallic composition comprising powdered wood and an adhesive binder is well suited for this purpose. Preferably this material is applied as a thick paste formed by the addition of a volatile solvent such as acetone to the material as manufactured and sold by the A. S. Boyle Company of Cincinnati, Ohio.

With the shell supported face down on a smooth surface, the paste may be pressed readily into the type cavities to insure complete displacement of air therein. The excess is leveled off to form a continuous coating of uniform thickness and having a smooth back surface. The filler is then allowed to set, which takes place rapidly in View of the volatile character of the solvent employed. If desired, an excess amount of the filling material may be applied and the coating ground down to the desired thickness and its surface made exactly parallel to the type face of the shell. Preferably the coating "Ia thus formed extends beyond the edges of the type face proper but the outer part of the marginal edges 6 is left uncovered.

The composite type-carrying sheet thus formed is relatively flexible and may be bent to conform to a backing surface of the curvature commonly used in standard printing presses without injuring the filling or distorting the type face. Since the fillings in the type cavities adhere to the shell surface without subjecting the shell to a temperature sufficiently high to cause distortion, the type face is virtually an exact reproduction of that of the original form` Printing plates constructed as above described may be used in at bed presses or in presses in which the plates are carried on the convex periphery of a cylinder 8. To enable the reinforced shell to be securely fastened to cylindrical or flat bed supports of standard construction, the shell is backed by a rectangularly shaped plate 9 preferably made of metal such as steel or brass and of a uniform thickness such that the combined thickness of the coated shell and the backing plate is substantially equal to that of the lead backed shells now generally used. With the shell coated as above described, a plate approximately 0.10 of an inch thick would be employed. The plate is preferably made slightly wider than the coating 'Ia but less than the width of the shell so that the marginal edges 5 extend beyond edges of the plate. For a reason to later appear, the plate may be made longer than the shell with other side edges projecting beyond the top and bottom marginal edges of the shell.

The backing plate is preformed to a uniform curvature corresponding to that of the press support upon which it is to be mounted. For use on the rotatable cylinder 8, the plate Would have one concave surface shaped to lie against the cylinder surface. On flat bed presses, at backing plates would ordinarily be employed.

To avoid wrinkling or other distortion of the coated electrotype under the severe lateral strains to which it is subjected during printing, the present invention contemplates drawing or forcing all of the contacting parts of the filled shell and backing plate together under pressure. This is accomplished by subjecting the shell to edgewise or lateral stress by applying oppositely directed forces to opposite side edges of the shell, the line of action of the forces being the same as the direction of movement of the shell when supported in the press. When used on a cylinder as shown in the drawings, the shell is placed under tension and thereby stretched over the convex surface of the backing plate 9. The shell is thus held taut and the under surface of the coating 1a is maintained in firm contact with the plate.

The means employed in thus stretching the shell on the backing plate may, as in the present instance, also serve to detachably secure the type sheet and the plate 9 together to form a unitary structure hereinafter called the printing plate assembly. Herein, this means comprises a pair ,of fastening elements in the form of flanges I8 formed along two opposite side edges of the shell on the rear side thereof. These anges may be formed from the metal of two of the marginal edge portions 6 by bending the outermost part of these portions backwardly around a suitable fixture plate (not shown) and then reversely and toward each other to form two opposed grooves conforming in shape to that of the opposite side edges of the backing plate 9 which constitute fastening devices engaging the fastening elements I9 when the plate and shell are assembled. The upper corners of the backing plate edges are rounded slightly as indicated at Il (Fig. 4) to form a gradual bend in the portions 6 in order that the stretching forces applied will produce a maximum degree of tension in the shell with a minimum distortion of the metal. The lower corners I Ia along the edges of the backing plate are made relatively square to minimize the tendency of the flanges to straighten out under the lateral tension to which the shell is subjected. In order to permit the back surface of the plate 9 to lie in contact with the surface of the cylinder, the flanges are seated in narrow grooves I2 formed along the edges of the plate on the underside thereof.

Preferably the free edges of the flanges I0 are stiffened which may be accomplished simply and effectually by corrugating the flanges by forming a series of closely spaced indentations I2 along their free edges.

One way of deriving the force for stretching the shell as above described is by the action of the backing plate 9 or a part thereof as a wedge when assembled with the filled shell. For this purpose, the plate, in the embodiment of the invention shown in Figs. l to 4, is constructed with surfaces which are inclined relative to the longitudinal side edges of the shell and which, when all or part of the plate is shifted longitudinally of the shell, cause the eifective width of the plate to be varied. If this shifting takes place with the plate lying against the filled surface of the shell, an outward pressure will be exerted on the flanges I thereby spreading the flanges apart and stretching the shell over the backing plate. In order that the plate 9 may have parallel side edges, it is made in a plurality of separate parts adapted to be assembled in abutting edge to edge relation at joints which are located intermediate the side edges of the plate and whose engaging surfaces form the wedges.

It is preferred to employ a backing plate come posed of two parts indicated as 9 and 9a in Fig. 3 which are substantially triangular in shape and, in the present instance, are right angle trapeziums united at a tongue and groove joint t3 which extends substantially diagonally of the backing plate. With the joint I3 inclined at this angle, the tendency of the two parts to buckle at the joint, under the tension to which the shell is subjected, is virtually eliminated inasmuch as this buckling tends to take place along a longitudinal line of the backing plate. The tongue and groove connection I3 eifectually holds the two parts in edgewise relation and yet permits the parts to be shifted relative to each other. Preferably the parts 9 and 9a are made of such length that their edges I4 project beyond the top and bottom or unlanged edges of the shell and are thus readily accessible for expansion or contraction of the shell.

It will be apparent that the rectangular plate formed as above described may, by lengthening the plate, be reduced to a Width where the plate Will drop in between the flanges IB and become alined with the grooves defined thereby. By forcing the ends I4 into the shell from opposite ends thereof, the plate is contracted longitudinally but expanded laterally, the side edges entering the grooves and eventually engaging the flanges I0. Further application of pressure to the edges I4 stretches the shell tightly over the backing plate which is usually applied by driving the triangular parts of the backing plate into the shell after the plate assembly has been mounted on the press cylinder. Preferably the inclination of the joint I3 relative tc the longitudinal center line of the plate that the friction developed when the shell is stretched over the backing plate will retain assembled relation of the plate and shell and prevent longitudinal shifting of the parts 9 and 9a. When the shell and backing plate are assembled, it will be apparent that they may be detached conveniently simply by pulling the ends I4 apart.

With the lled shell and the backing secured together in the manner above desI it will be apparent that a substantially gid plate assembly is formed which, in thickness and general shape, closely approximates that of standard lead backed electrotypes. The plate assembly may therefore be secured to a printing cylinder by the use of clamping devices of standard construction. As shown in Figs. these clamping devices generally comprise block I5 bearing along one edge on the cylinder surface. 'Ihe opposite edge has a lip I3 overlying the upper surface of the marginal portions c of the shell and bearing against the same opposite the rounded edge II of the backing plate. The clamping action is obtained by tightening screw I1 threading into a block IS seated in :in undercut groove I9 extending spirally around the cylinder. Several of these clamping devices may be applied to the beveled projecting edges ifi of the backing plate so as to press the intermediate portion of the plate assembly firmly against the supporting surface and avoid any buckling tendency. Inasmuch as the shell is stretched over the backing plate in the direction of motion of the shell when mounted on the press cylinder, it is not necessary that the clamping devices at the top and bottom of the page overlie the correspending marginal edges of the shell.

After the plate assembly has been placed in proper position on the press cylinder and before the clamping devices have been fully tightened down, the plates 9 and Se are driven into the shell so as to produce the desired degree of tension in the shell. Then when the clamps are tightened, all of the edges of the plate assembly will be pressed rmly against the upper surface of the cylinder and the assembly securely held in place. The stiifening of the free edges of the anges resulting from the formation of the transverse indentations I2 overcomes any tendency of the flanges to straighten out or pull through between the cylinder and the edge IIa of the backing plate when the latter is expanded. The abrupt edge IIa which engages the flanges I0 behind the indentations I2 also assists in overcoming the tendency of the flanges to straighten out under tension.

With the foregoing method of reinforcing and mounting the shell, it will be apparent that the subjection of the shell to a distorting temperature is completely eliminated and that the reinforced shell is so flexible that it can be bent to the proper curvature without distortion of the type face. Therefore, the latter is a true reproduction of the original form. Such a high degree of accuracy in reproduction is particularly desirable in multi-color printing where one shell must be made for each basic color used and where proper blending requires that the different color impressions be superimposed upon each other in perfect register. Since the present invention enables a plurality of true reproductions of the original form to be made, this requirement is satisfied with a minimum expenditure cf time and labor both in the preparation of the shells and in the mounting thereof in the press.

Moreover, the original size and shape of the dots which are formed in relief on the type faces to produce the half-tone or shaded effect are effectively preserved. This is because the shell is not subjected to hammering or other distorting forces as is commonly done in present practice in order to Work the shell surface back into its original shape after application of the lead backing.

The high degree of accuracy obtained with the present process is also advantageous in that it eliminates, in some instances, the necessity for detail make-readies which are commonly ernployed for removing imperfections in the type face and for bringing out the solids, Where such make-readies are required, their complexity, that is the number of make-ready details or spots required to be pasted onto the makeready sheet, is reduced to a minimum and the make-ready accordingly simplified.

With the type cavities iled as above described, the inherent fiexibility of the shell is preserved to a substantial degree, at least to an extent which enables the reinforced shell to respond under normal printing pressure to the detail make-ready placed directly beneath the filling material. The make-ready is in the form of a paper sheet 20 bearinfJ the usual details or patches 2| pasted to the sheet in positions opposite those portions of the type face which are to be raised. Preferably, the sheet 20 is a proof taken from the type face in a special proving press while the shell is secured to a temporary backing plate, and the patches 2| may be cut from other proofs and pasted to the sheet 2U over the parts of the sheet corresponding to those of the printing surface to be raised.

While the detail make-ready may be prepared as a separate detached sheet, proper location of the original make-ready patches or those additions that may occasionally be required to be made in the press room may be greatly facilitated by securing the proof sheet 20 to the surface of the coating 1a, as by the use of paste, with the printed parts of the proof in register with the corresponding parts of the type face. Then, to raise a particular part of the type face so as to cause the desired added pressure to be applied during printing, it is merely necessary to paste a patch of the proper thickness over the corresponding part of the proof sheet. The detail make-ready thus becomes a permanent part of the reinforced shell and may be stored and preserved with the shell for the printing of future issues of the book or other publication. The relation of the type face and make-ready being thus established, there is no danger of slippage between the two after the plate assembly has once been mounted in the press.

By providing a reinforcement for the shell which enables the detail make-ready to be mounted directly beneath the shell instead of on the impression cylinder as is necessary in present practice, the preparation of the make-ready is greatly facilitated, the size of the packing cylinder is kept equal to the plate cylinder, and in addition the time required in making of the press ready for printing is materially reduced. During preparation of the make-ready sheet, the filled shell may, owing to its flexibility, be proved while supported on a surface of a different curvature from that on which it will ultimately be used in actual printing. The preparation of the make-ready sheet and the location thereof with respect to the shell may therefore be carried on in advance of going to the. press without tying up the costly press equipment as is now done in present practice and the make-ready may be prepared in a separate department by specially trained workmen. The present method of preparing the make-ready is also facilitated by the provision, in the present construction, for ready detachment of the shell from the backing plate and remounting of the plate assembly which ordinarily must be repeated several times in the course of preparing the make-ready. With the make-ready thus mounted, shifting of the plate assembly for final register or line-up does not require opening of the packing cylinder for shifting the make-ready to correspond with the shift of the plate.

In certain types of presses, it is customary to emphasize certain parts of the lead backed shells now used by pressing the same under hydraulic pressure between an underlay and an overlay. The necessity for thus treating the shell is completely eliminated by the present invention because the filled shell is so flexible that it will respond to an underlay placed beneath the shell. Furthermore, the underlays may be corrected quickly and conveniently.

As used in the appended claims, the expression make-ready details is intended to refer to those paper patches or spacing elements which are used in productive printing on machine finished or uncoated paper for the purpose of emphasizing selected and Well defined areas-of socalled solids and relieving the high lights" under pressure normally applied during printing, such patches having heretofore been mounted on the impression member of the printing press so as to constitute a so-called overlay.

Fig. illustrates a modification of the present invention in which the shell 5 and the backing plate 9 are not assembled as a unitary plate as in the preferred form above described. In this modification, the backing plate may be a single sheet of metal and the marginal edges of the lled shell formed with ribs 22 along their upper edges, preferably from the metal of the marginal edges 6. The clamping devices 23 employed are formed with hooked ends 24 adapted to engage behind the ribs 22 and apply the stretching forces to the shell when the clamps are tightened down. To enable this action to be obtained, the shell is made of such width relative to the backing plate that the ribbed edges will not contact the surface of the supporting cylinder until the clamps have been applied and tightened down.

Figs. 6, 7, and 8 illustrate still another method of securing the shell, when reinforced in the manner previously described, to the backing plate and securing the plate assembly to the press cylinder. In this modification, the backing plate, numbered 25, is an integral sheet with grooves 26 formed along two opposite side edges and lugs 21 formed at the other edges to receive screws 28 by which the plate is clamped in place on the press cylinder 8. The marginal edges of the shell to which the stretching force is to be applied are formed with tongues 29 adapted to enter slots 30 in narrow bars 3| which are then turned through a revolution or more and the uncoated edge portions of the shell thus wrapped around and secured to the bars. At their opposite ends, the bars are formed with lugs 32 which are adapted to be clamped to the press cylinder by screws 33.

In mounting the shell by this method, the plate 25 is first secured in place on the cylinder. Then one of the bars with the shell wrapped therearound is secured in place with the bar received in the adjacent groove 26 of the plate 25 as shown in Fig. 8. Then the stretching force is applied to the other bar and the latter nally clamped in place spaced slightly from the groove 26 as shown in Fig. 7.

From the foregoing, it will be apparent that the present invention not only enables a more exact reproduction of the original form to be obtained, but the cost of preparing printing plates and mounting the same in a press is materially reduced. These important results are attained first through the reinforcement of the delicate shell by a thin and flexible filling which may be applied without exposing the shell to a distorting temperature; second through the provision of the present method of and means for securing the thin shell to a supporting surface; third by reinforcement of the shell to enable the detail makeready to be located directly beneath the shell coating; and fourth by the construction of the plate assembly which permits its use with standard press equipment.

The capital investment tied up when the plates are stored for the printing of subsequent issues of a publication is materially reduced in view of the small cost of the filling 1 as compared to the lead backing now generally used and the further fact that the backing plates need not be so stored but may constitute a part of the press equipment. Since the detail make-ready may be made a permanent part of the filled shell, the preparation of new make-readies, as is necessary in present practice preparatory to the printing of a new issue, is also avoided with the present invention. With the non-metallic reinforcing coating preferably employed, reclamation of the shell copper is greatly facilitated.

I claim as my invention:

1. The combination with a flexible type-carrying sheet of rectangular shape of metallic flanges rigid with two opposite side edges of said sheet and bent backwardly from the face of the sheet and then reversely and substantially parallel to the sheet, said reversely bent flange portions being formed with longitudinally spaced indentan tions whereby to stiffen the flanges against bending.

2. The combination with a printing press support having a surface upon which a printing member is to be mounted, of a separately formed expansible plate conforming to the contour of said surface and shiftable edgewise along said support while lying against the same, said plate having parallel marginal edges with fastening devices extending therealong and disposed above the surface of said support, a type-carrying sheet overlying said plate and having fastening elements spaced for engagement with said devices, said plate comprising at least two separate sections cooperating to form a continuous backing for the type on said sheet and abutting each other in edgewise relation and movable relative to each other in one direction while said devices and elements are engaged to expand the plate in an edgewise direction and thereby stretch said sheet over the plate surface to form a unitary printing plate assembly, and means for securing said assembly detachably to the surface of said support while permitting of bodily edgewise adjustment of the assembly in any direction along the surface of said support.

3. The combination with a printing press support having a surface upon which a printing member is to be mounted, of a separately formed expansible backing plate conforming to the contour of said surface and shiftable edgewise in any direction while lying against said support, said plate having fastening devices extending along opposite marginal edges and disposed above the surface of said support, a type-carrying sheet overlying said plate and having fastening elements spaced for engagement with said devices, said plate comprising at least two separate sections cooperating when in edgewise abutting relation to form a continuous backing for the type on said sheet and shiftable relatively to each other while. said devices and elements are engaged, to expand the plate in an edgewise direction against said elements and thereby stretch said sheet over the plate surface to form a unitary printing plate assembly, and clamping devices on said support overlying the edges of said assembly and acting to fasten said assembly to said support, said clamping devices being detachable to permit of bodily edgewise adjustment of the assembly in any direction along the surface of said support.

4. A printing plate attachable to the surface of a type support of a printing press comprising, in combination, a flexible sheet having type projections and fastening means at opposite edges, and a separately formed expansible backing member underlying said sheet, and means interengaging with said fastening means to stretch the sheet over the member upon expansion of the latter in an edgewise direction, said backing member and type sheet forming a unitary assembly conforming to the contour of said support surface and adjustable in any direction therealong.

ARTHUR B. DAVIS.

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