US2806425A

US2806425A - Process for preparing inking rollers for multicolor inking of a printing plate

Info

Publication number: US2806425A
Application number: US140028A
Authority: US
Inventors: Giori Gualtiero
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-01-23
Filing date: 1950-01-23
Publication date: 1957-09-17
Anticipated expiration: 1974-09-17
Also published as: CH290601A; BE498805A; NL79012C

Description

p 17, 1957 G. GIORI 2,806,425

PROCESS FOR PREPARING INKING ROLLERS FOR MULTICOLOR INKING'OF A PRINTING PLATE Filed Jan. 23, 1950 INVENTOR.

V Gang/5 0 (310m ATTORNEYS PRGCESS FOR PREPARING INKING ROLLERS FOR MULTICULOR llNKllNG F A PRINTING PLATE My invention relates to printing processes, and more particularly to a multicolor printing process of the kind in which a single printing plate is inked with several colored inks distributed on zones upon said printing plate. It refers, still more particularly, but not exclusively to a method for preparing printing plates and inkingrollers from a single original plate for intaglio printing.

One object of the invention is to produce a print where the color in the different zones are positioned therein with extreme accuracy.

Still further objects will appear from the following specification, in which my invention, as well as the means to carry it out, is disclosed.

In order to make this description clearer and to understand the nature and extent of my invention I will give a brief description of the prior known art.

Processes for multicolor have been known for many years. One of the oldest processes consists in inking by hand a single printing plate with several inks of different colors, spread over separate or adjacent areas on the plate, which is then printed on a paper or other suitable material. All the colors are thus printed in a same operation. Many art engravings are printed in colors this way.

As a development of the process in which the inking was made by hand, P. Bonnier invented the process described in U. S. Patent No. 1,108,063 of August 18, 1914, in which the inking was'made by means of auxiliary inking rollers. .This process consisted in inking a single printing cut with the necessary inks, by means of as many auxiliary inking rollers (interposed between the printing cut and the printing cylinder) as colors had to be deposited on the printing cut. Each of these auxiliary rollers were coated with a coat of a resilient material (gelatin, india-rubber or other) and had a circumference corresponding exactly to the length of the printing cut or plate to be inked. The coating of resilient material was cut oh by hand or by chemicals so as to leave only certain protruding zones corresponding to the area of the printing plate that should be inked with that particular ink. If a print in two colors, for instance, was to be made, two auxiliary inking rollers were prepared and each one was inked with a different ink. Thereafter the two rollers were passed upon the printing plate or cylinder, so as to deposit the two inks on the corresponding areas of the surface of the printing plate. If the printing plate, hear ing the .two inks, was pressed against a sheet of paper, a bicolor print Was obtained through only one printing operation.

The auxiliary inking rollers in accordance with that process were prepared or made as follows: the printing plate was first made and inked with any ink. Then the auxiliary inking rollers, covered with a uniform coating of resilient material, were rolled upon the printingplate in order to obtain a printon their surface. As many inking rollers were prepared that way as colors were to be finally printed. The print on their surface was a guide Patented Sept. 17, 1957 2. for cutting off from each one of them the areas which had to be inked by another inking roller or rollers.

Many objections were raised against that process. It did not permit the required accuracy in the registry of the diiferent colors applied on the printing plate. Sometimes the colors unduly superimposed one on the other and sometimes they were kept apart leaving blank spaces. The design or pattern printed by the printed plate on the surface of the inking rollers, did not permit the obtaining of a cutting which would take into account the shape of the design of the engraving of the printing plate. Therefore the possibility of forming inking areas to ink the plate with color areas different from the design in the printing plate was very restricted. Moreover, the operation of the printing press had to be stopped in order to mark the design of the plate on the surface of the inking rollers.

That method, as admitted by Mr. Bonnier, although being useful for commercial purpose could not be used in the printing of securities, banlonotes, stamps and other prints requiring a very high degree of correctness and accuracy.

The Bonnier process did not permit, furthermore, the multicolor printing in intaglio. Consequently that method could not be used for printing securities or bank notes.

Now I have invented a process for multicolor printing with a single intaglio or letterpress printing plate, inked with several inks, which does not present the aforesaid inconveniences and allows the attainment of a very high uniformity of coloring in a great number of prints, say in the range of thousands or millions.

It is well known that the intaglio printing differs from the letterpress printing because in the first place the printing surfaces are depressed and in the second place the printing surfaces are protruding. This causes the necessity, during the inking of the intaglio plate, to exercise a certain pressure of the inking roller against the printing plate in order to fill the grooves of the plate with ink.

If the inking rollers are given (as it has previously been done) a circumference corresponding to the length of the printing plate, when they are pressed and rolled upon the printing plate surface their radius shortens and, as a consequence, the ink deposited on the printing plate covers an area smaller than the area that ought to be inked.

One of the fundamental principles of my invention for obtaining an always identical multicolor intaglio print, consists of inking rollers, which instead of having a circumference corresponding exactly to the length of the printing plate, as in other known processes, have a circumference greater than the length of the printing surface of the printing plate.

This increase of the circumference of the inking roller is calculated so as to make the distance between the printing plate surface and the axle of the inking roller, during the inking operation, be the radius of a circumference corresponding exactly to the length of the printing surface of the printing plate.

The method I invented essentially consists in: engraving a matrix printing plate in any suitable way; marking it with reference marks (lines, angles, etc); taking from this matrix plate, thus marked, as many identical printing plates as required for printing pur poses and an extra printing plate; placing on the extra plate a transparent sheet of film on which lines demarking the areas to be inked in the plate and lines corresponding to the marks on the plate are drawn; making the extra plate photographically sensitive after taking oif the film; taking a photographic copy of the drawn sheet on the sensitive extra plate; etching the lines thus reproduced on the extra plate thus obtaining a plate identical to the matrix but bearing the areas demarking lines; moulding inking rollers having a per:

face of the rollers so a to leave only thealreas to be.

inked with particular ink in each roller.

In the drawings, given as an example of embodiment of the invention:

Figure 1 shows part of a, printing plate, containing a number of engravings or units, and a film placed upon one of the units;

Figure 2 shows the film on which the angles of a unit have been drawn as reference marks;

Figure 3 shows the film on which the lines demarking the several colored areas have been drawn;

Figure 4 shows an angle of the, extra plate, which will be called hereinafter marking plate, on which the lines demarki-ng the several color areas have been etched.

In accordance with my invention, and to carry out the process to which this patent refers, I begin by making the printing plates. The printing of a high number of prints requires the use of a plurality of intaglio or letterpress printing plates that must be absolutely identical and the use of a plurality of inking rollers which also must be absolutely identical and always identically cut. For this purpose I make, by any known method, and preferably by means of the electroforming process a metallic matrix plate. On the metallic matrix some reference marks at the angles -of the drawings or in any suitable place, and two horizontal lines, at the top and bottom of the engraving and at a certain distance from the upper and lower edges and exactly parallel to these edges are engraved. The plate bearing cylinder of the printing pres I preferably use for printing in accordance with my method (which press is the subject matter of my United States Patent No. 2,659,305 issued November 17, 1953) bears on its border a millimetric scale. The horizontal lines engraved on the plate allow the perfect mounting in po sition of the plates on the cylinder, thus insuring that all the successive printing plates mounted on the press be in an identical position.

As shown in Fig. 1, upon one of the units engraved on these printing plates 1 (usually the engraving to be printed consists in a number of repeated units or drawings) a transparent sheet or film 2 is fixed and on this film the exact position of the engraved drawing angles are drawn. Figure 2 shows the film on which angles 4, 4, 4" and 4 have been drawn. These angles correspond exactly to the

angles

3, 3', 3" and 3" of one of the engraved units shown in Fig. 1. Then the divisor-y lines of the various areas to be inked in several colors, are drawn on the film (see Fig. 3). Letters or numbers corresponding to each color, and there fore to each inking roller, are also written on the film: in the example of Fig. 3 letters A, B, C, D and .E have been drawn. The fitlm thus prepared will be called hereinafter Selection Guide.

From the selection guide as many photographic diapositives are taken as units appear on plate 1. These diapositives are placed on the printing plate with the angles of each unit (as previously drawn in on the selection guide) accurately coincident to the corresponding angles of the engraved unit. Then the plate, which has been previously made photographically sensitive, is printed by known photomechanical means. The operation is completed by etching the divisory lines previously printed on the plate. Thus a plate, identical to those which will be used for printing the final prints, is obtained but this plate has also engraved the divisory lines of the different areas to be inked and the numerals or letters correspond ing to the several inking rollers. The plate 11, so marked, will be called hereinafter marking plate (see Fig. 4).,

It is obvious that thelines enclosing the areas to be inked may be drawn on the'film on the basis of the drawing to be printed, or may be drawn so as to form geometrical or fanciful designs particularly for the background areas.

All these operations may be reduced to only one if one has a photomechanical multiplying machine wherein the selection guide and the marking plate, which has been previously made sensitive, may be placed to print on the latter automatically the selection guide as many times as are the units on the plate.

The marking plate 11 serves to mark the inking surface of the inking rollers, which bear a coating of resilient material or are totally made from resilient material. Said rollers may be formed in any suitable Way (injection, extrusion, application of sheets obtained through calendering) but it is necessary to exclude in the composition of said coating any hygroscopic material (as it has been done in other processes) in order to avoid that in consequence of changes of temperature and especially of moisture, the coating suffers changes which would modify the inking areas. This would render impossible the attain,- ment of an always identical multicolor printing. Moreover the coating of the inking rollers has to be performed so they will be perfectly concentrical, with their periphery always identical and with a surface particularly capable.

to do a perfect inking and with the required and constant degree of hardness. The diameter of these inking rollers must be calculated as aforesaid.

The printing plates and the inking rollers made as stated above, may be mounted in any suitable printing press for printing the final prints, but the best results are obtained if they are used in the printing press of my invention, which is the object of Patent No. 2,659,305. Said printing press comprises means to regulate the pressure of the inking rollers against the printing plate allowing thus the control of the deformation of the inking areas of the rollers; and a printing plate bearing cylinder having a curvature corresponding to that of the respective sector of the transferring apparatus herein described, so that no differences due to different deformation of the printing plate and the marking plate may arise.

The above described process and the use of the trans ferring apparatus allow the cutting of the rollers without using the press, whose work is never stopped for this purpose.

While I have described in detail a certain embodiment of my invention, it will be obvious to those skilled in that art that many improvements and modifications may be made therein within the province of the invention; and I have set forth details only to enable those skilled in the art to understand how my invention may be used in a preferred form.

Therefore, what I claim as my invention is:

1. A method of making inking rollers having a coating of, or made from, resilient material, and printing plates for conjoint use in multicolor printing presses of the kind in which a single printing plate is inked, over predetermined areas, by means of at least two inking rollers bearing, each of them, a predetermined color, which-method consists in marking a matrix with reference lines to ensure that the printing plates made therefrom can all be identically mounted on the printing press, making from the matrix thus marked a plurality of identical intaglio printing plates, placing on one of these plates, the marking plate, a transparent sheet and drawing on this sheet reference marks corresponding to parts, such as the corners, of the image on said marking plate, and lines demarking the areas to be printed in separate colors, writing in each self-contained area indicia corresponding to an inking roller, making said marking plate photographically sensitive, copying photographically on it the drawn sheet by placing it over said marking plate and by registering the reference marks previously determined, etching the lines copies on the marking plate, forming resilient inking rollers, printing on the surface of said rollers the design on said marking plate, and engravingthe surface of said rollers thus marked so as to leave projecting only the areas to he inking areas of each individual roller.

2. A method of making inking rollers having a coating of, or made from, resilient material, and printing plates, for conjoint use in multicolor printing presses of the kind in which a single printing plate is inked by means of a plurality of rollers, each one bearing a different ink, With at least two inks, which method consists in marking a matrix having a plurality of identical units on its surface, With reference lines to ensure that the printing plates made therefrom can all be identical-1y mounted on the printing press, making from the so marked matrix as many identical intaglio printing plates as are required for the printing operation, and an extra printing plate called the marking plate, fixing a transparent film on said marking plate, drawing on this film reference marks corresponding to parts, such as the corners of one of the units and lines demarking the different colors, photographically reproducing as many diapositives from the drawn film as there are units on the matrix, making the marking plate photographically sensitive, placing, registering upon each unit, and printing said diapositives on said sensitive marking plate, etching the lines thus marked on said marking plate, forming the resilient inking rollers truly cylindrical, printing the rollers thus obtained with said marking plate by rolling the rollers on said marking. plate, or vice-versa, and engraving said rollers surface except in the areas to be inking areas of each individual rollers.

References Cited in the file of this patent UNITED STATES PATENTS 565,891 Frauenfelder Aug. 18, 1896 1,108,063 Bonnier Aug. 18, 1914 1,260,824 Smith Mar. 26, 1918 1,271,949 Saalburg July 9, 1918 1,276,697 Hertlin Aug. 20, 1918 1,534,292 Ball Apr. 21, 1925 1,547,776 Ball July 28, 1925 2,000,094 Peterson May 7, 1935 2,036,835 Sites Apr. 7, 1936 2,303,646 Lathey Dec. 1, 1942 2,349,900 Bourges May 30, 1944 2,499,870 Luehrs Mar. 7, 1950 FOREIGN PATENTS 334,183 Great Britain Aug. 22, 1930