US2977876A - Printing plate construction - Google Patents

Description

April 4, 1961 R. R. MYERS PRINTING PLATE CONSTRUCTION Filed Nov. 3, 1958 flited states 2,977,876 PRINTlNG PLATE CONSTRUCTION Robert R. Myers, 561 Washington, Chicago, Ill. Filed Nov. s, 1958, Ser. No. 771,584 3 Claims. 01. 101-375 This inventionrelates to the art of printing plates and i more particularly to one having an attachable rigid backing plate.

The present method of making printing-plates is slow and tedious. The prepared printing shells are inverted and subjected to molten backing material. This build up of the shell is relatively thick and after it has cooled tionally heavy due to its volume. Most backing material is approximately ninety-four-percent (94%) lead, three percent (3%) tin, and three percent (3%) antimony.

While the backing material is thus of a very heavy nature, it is not strong and obviously has the possiblejcharacteristic of bending. Obviously due'to the softness of the backing material, the press clamp members may penetrate the plate resulting in the plate becoming loose on the press and buckling and breaking. This combination of objections in the common printing plate places many restrictive limits on the speed on which the press may be operated. In the case of rotary presses, the weight of the plates causes centrifugal force to build up rapidly with the result that the plates tend to bend outwardly and either break or produce undesirable, irregular printing. Still another objection to the common printing plate is the time aspect. Considerable time must be taken in permitting the backing material to cool after it has been placed on the shell.

Obviously this problem of making and having heavy printing plates is most present in newspaper Work where time is a factor and the printing plate is only used for a single run. Most newspapersuse stereotypes which in themselves are only approximately of an inch thick. Some effort has been made to eliminate the heavy backing material back of the stereotype by making the backing plate of laminated material, such as sheets 'of plastic and steel. However, even with laminated base plates valuable materials are wasted.

Therefore, one of the principal objects of my invention is to provide a printing plate that has a detachable backing plate that may be easily and quickly removed after thevplate has been used, for subsequent service as a backing plate'for new stereotypes, printing shells, or like.

A further object of 'my'invention is to provide a'printing plate that may be rapidly fabricated.

A still further object of my invention is to provide a strong printing plate that will stand hard and long usage.

A still further object of my invention is to provide a printing plate that is relatively light weight.

seven-sixteenths' Patented Apr. 4-, 1961 Still further objects of my invention are to provide a printing plate that is economical in manufacture, and does not necessarily require the service of skilled workmen in the assembly thereof.

These and other objects will be apparent to those skilled in the art.

My invention consists in the construction, arrangements, and combination, of the various parts of the device, whereby the objects contemplated are attained as hereinafter more fully set forth, specifically pointed out in my claims, and illustrated in the accompanying drawings, in which:

Fig. 1 is an exploded perspective view of a printing surface and a tough metal sheet member for permanent attachment thereto,

Fig. 2 is an end View of the printing surface plate and metal sheet after the two have been secured together,

Fig. 3 is a perspective reduced view of my attachabledetachable backing plate,

7 Fig. 4 is an end view of a simple mechanical clamping device for attachably securing the portion shown in Fig. 2 to the backing plate shown in Fig. 3. A section of the printing plate is cut away to more fully illustrate its construction, and

Fig. 5 is an enlarged cross sectional view of one end 1 portion of my plate not having incorporated therewith a resilient end strip such as is used in Fig. 3.

Although I show in my drawings an arcuate printing plate, obviously my invention may also be used for fabricating fiat printing plates. In general, my method is to take the original engraving or printing face plate, secure the same by any suitable adhesive to a metal sheet and then detachably secure the metal sheet to a p're-formed backing plate of light metal.

In the drawings I have used the numeral 10 to designate a printing surface plate, stereotype, engraving or like.

If the printing surface plate 10 is a fragile printing shell it may be strengthened or laminated at its rear.

The numeral 11 designates a sheet of steel or like preferably approximately point zero one eight (.018) of an inch thick. This sheet 11 has a width substantially greater than that of the printing surface plate 10 in order to provide tab portions 12 and 13 at each side of the printing surface plate 10 when the two are secured together. In the tab portion 12 I provide a plurality of holes 15. In assembling the two sheet plates 10 and 11, I use an adhesive 16, and which is applied between the plate 10 and sheet 11, as shown in Fig. 1. This adhesive may be a cold suitable glue or it may be a suitable thermo glue. A good adhesiveis one made by the Minnesota Mining and Manufacturing Company, of Saint Paul, Minnesota, under the trade name Cycle Weld. Still another acceptable adhesive is a thermosetting adhesive of the type which adheres readily and comprising essentially a phenolic resin and a polyvinyl acetate resin and a polyvinyl acetate resin in the approximate ratio of 3:1 known commercially as Bostik 7008 and manufactured by the B. B.'Chemical Company, of Cambridge, Massachusetts. If a hot type adhesive is used the printing surface plate It) and sheet 11 are heated and pressed together andthen allowed to cool. During the pressing operation, the unit may be curved as shown in Fig. 2. Also, at this time or thereafter, the tab portion 1?. of the metal sheet is bent inwardly and to an acute angle, as shown by broken lines in Fig. 2. The numeral l7.designates a detachable backing or base plate and which is pre-formed of light weight metal such as magnesium or aluminum alloy. Obviously this backing plate 17 is much thicker than that of the combined thicknesses of the parts 10 and 11. One side edge of the backing plate 17 extends inwardly and downwardly and approximately at a forty-five (45) degree angle, as shown in Fig. 4. Extending from this inwardly beveled side edge of the backing plate 17 is a plurality of finger lugs 18. These projections 18 are of the same number and are so arranged as to engage the holes 1.5 of the'sheet 11 as shown in Fig. 4. other side edge of the'base plate 1'7 is also beveled to extend inwardly and downwardly as shown in Fig. 3. However, integrally formed on this latter side edge is an elongated hook rib portion or circular flange 19 as shown in Fig. 3. As before indicated, the drawings illustrate an arcuate printing plate and therefore when an arcuate printing plate is to be produced, this backing plate 17 is arcuate as shown in the drawings.

Any suitable means may be used to drawand secure the unit shown in Fig. 2 onto and around the outside of the backing base plate 17. In the drawings 1 show a simple clamping press generally designated by the numeral 20 and having a circular cavity 21. The numeral 22 designates a horizontal projection extending a distance over and above one side area of the circular cavity 21, asshown in Fig. 4. This portion .22 acts as a stop ledge for one side edge of the printing plate being assembled.

In producing the printing plate, the metal sheet 11 is placed around the outside of the backing plate 17 with the holes of its tab portion 12 embracing the lug projections 18. The parts of the printing plate are then placed in the press 20, the tab portion 12 engaging the underside of theledge portion 22. At this stage in the assembly the tab portionv 13 of the metal sheet 11 will be extending approximately in a vertical position. The purpose of the tab portion 13 is to provide a bendable portion to embrace and hook onto and around the rib flange 19. The numeral 25 designates a handled clamping and pressing jaw rotatably mounted on the press and adjacent the tab portion 13. This jaw has its effective side shaped to conform with the structure of the side edge of the backing plate 17 that is opposite from the projecting lugs 13. Therefore, by' swinging the jaw 25 inwardly, it will engage the tab end portion 13 of the metal sheet and force the same in hooked relationship onto and around the hook rib 19 6f the back plate 17. This action and movement of the jaw 25 is shown by broken lines in Fig. 4. Inasmuch as the final closing movement of the jaw 25 is downwardly relative to the press 20, the printing plate will be forced tightly downwardly in the press opening 21 and tightly against the limiting stop ledge 22 of the press. This action will tightly pull the metal sheel 11 carrying the printing plate surface 10 around the backing plate 17, thus producing a tight laminated printing plate. To further ensure a tightly laminated printing plate unit, not only at time of assembly but during use, I have provided a flexible, resilient strip 26 of rubber or like between the beveled edge of the backing plate 1'7 and the tab hook portion 12 of the metal sheet as shown in Fig. 3 and Fig; 4. This flexible, resilient strip will yieldingly retain the metal sheet in taut condition around the backing base plate 17. In some constructions this flexible, resilient strip 26 may be dispensed with as shown in Fig. 5.

After the printing plate has been clamp-assembled in the press or like, the jaw 25 is swung outwardly and the assembled printing plate removed for immediate use.

After the printing plate has served its purpose, either the clamped tab end 12 or the clamped tab end 13, or both, are pried upwardly away from their clamping arrangement on the backing plate 17, at which time the metal sheet 11 and printing surface plate 10 are detached from the backing plate portion 17. By this arrangement the valuable backing plate 17 is quickly salvaged for use again with a different printing unit as shown in Fig. 2.

From this description of my invention it will be appreciated that I have not only provided a most rapid method of assembling and fabricating printing plates but have provided a system ofre-using certain parts of the printing plate for subsequent use, with different printing surfaces. Furthermore, by making the re-usable backing plate 17 of tough but light metal, I am able to produce a printing plate capable of extended long printing runs.

Some changes may be made in the construction and arrangement of my printing plate construction without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims, any modified forms of structure or use of mechanical equivalents which may be reasonably included within their scope.

I claim:

1. In a printing plate, an arcuate backing plate having a plurality of spaced apart permanent finger lugs on one of its side edges, a metal sheet having a plurality of holes in one of its side edge portions detachably embracing said finger lugs respectively, a resilient pad member between that end of the said metal sheet having said plurality of holes and the side edge of said backing plate having said finger lugs, a hook flange on the other side edge of said backing plate; said metal sheet extending over the back surface of said backing plate and having its other side edge portion bent over said hook flange, and a printing surface portion on the outer face side of said metal sheet.

2. In a printing plate, an arcuate backing plate having a plurality of spaced apart permanent finger lugs on one of its side edges, a metal sheet having a plurality of holes in one of its side edge portions detachably embracing said finger lugs respectively, a resilient pad member between that end of the said metal sheet having said plurality of holes and the side edge of said backing plate having said finger lugs, a hook flange on the other side edge of said backing plate; said metal sheet extending over the back surface of said backing plate and having its other side edge portion bent over said hook flange, and a printing surface portion on the outer face side of said metal sheet; said side edge of said backing plate having said finger lugs extending inwardly and downwardly relative to the curvature of said arcuate backing plate.

3. In a printing plate, an arcuate backing plate having a plurality of spaced apart finger lugs on one of its side edges, a metal sheet having a plurality of holes in one of its side edge portions detachably embracing said finger lugs respectively, a resilient pad member between that end of the said metal sheet having said plurality of holes and the side edge of said backing plate having said finger lugs, means for securing the other side edge of said backing plate to the other side edge of said metal sheet, and a printing surface portion on the outer face side of said metal sheet. 1

References Cited in the file of this patent UNITED STATES PATENTS 1,976,640 Upshaw Oct. 9, 1934 2,165,233 Curtis July 11, 1939 2,218,451 Heyne Oct. 15, 1940 2,248,275 Lengel July 8, 1941 2,512,940 Janke June 27, 1950 2,629,324 Smith Feb. 24, 1953 2,663,349 Albrecht Dec, 22, 1953 2,706,947 Albrecht Apr. 26, 1955 FOREIGN PATENTS 223,756 Great Britain Oct. 30, 1924 619,076 Great Britain Mar. 3, 1949

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