EP0133328A1 - Perfecting rotary multicolour printing machine - Google Patents

Abstract

The machine can print on one of the paper sides an image with juxtaposed colors by means of a typographic plate cylinder inked by a collecting cylinder inked in turn by selective color inking cylinders of which the number corresponds to the number of colors, and on the other side an image with superposed colors and designs by means of offset plate cylinders contacting an offset blanket cylinder and of which the number corresponds to the number of colors and designs of this image. For this purpose the machine comprises another blanket cylinder contacting the typographic plate cylinder and pressed against the offset blanket cylinder, the paper passes between this cylinder and the other blanket cylinder. The multicolor printing on the side receiving the image with juxtaposed colors may be completed by a monochrome wet offset print.

Description

The invention relates to a multi-color rotary printing machine for simultaneous two-sided printing.

Already known from the published German patent application (DE.A-3,109,964) a printing machine ensuring on one side of the paper the printing of an image in juxtaposed colors. This image is printed by means of a single typographic printing plate representing the complete drawing to be printed and mounted on a plate cylinder. This typographic plate is inked by a collecting cylinder formed by a blanket cylinder which is in turn inked by a plurality of color picking cylinders, the number of which corresponds to the number of colors in the image to be printed. Each selector cylinder has areas cut in relief representing the parts of the image to be colored in a determined color as its own inking device transferred to him. This machine is used in particular to print the security background for banknotes.

This process, which is commonly called "Orlof" or collector color printing, gives a multicolored image ensuring perfect register between the different colors of the drawing of the image, a result impossible to obtain with any other printing process. Since the color selector cylinders are in contact with an elastic surface of the collecting cylinder, they can be made of hard material which makes it possible to cut out very fine raised areas, therefore very fine colored parts, for example in the form of lines or dots.

On the other hand, indirect typographic or offset printing with colors and overlapping designs is known which, too, is often used to print security funds. According to this method, the complete drawing is composed of partial drawings of different colors carried by offset printing plates mounted on plate cylinders so as to allow the superimposition of drawings and colors in register with each other on a cylinder blankets against which the paper to be printed is pressed. The number of offset printing plates and, consequently, of plate cylinders corresponds to the number of different colors and designs composing the multicolored image.

There are also machines of this type for simultaneous two-sided printing in which the paper passes between two blanket cylinders. each receiving a multicolored image of the corresponding offset plate cylinders.

At the stage of the current technique, machines have each been developed which separately use one or the other of the methods described above.

The object of this invention is to create a single machine which combines in a simultaneous two-sided printing the two methods described above and called below the "Orlof" method and the offset method.

To achieve this goal, the machine is characterized by the characteristic clause of claim 1.

The advantage of this machine is that it makes it possible to use at the same time two completely different processes to print in a single pass an offset image on one side and an "Orlof" image on the other side, which offers to the user for the first time the possibility of printing in particular security funds on the two sides of a bank note by two different methods; this increases security against forgery and also makes printing operations more economical because the user does not have to use two separate machines.

Advantageous embodiments of the invention are described in the dependent claims.

The invention will be described by way of nonlimiting example by an embodiment and a variant with reference to the accompanying drawings.

Figure 1 schematically shows a printing machine according to the invention.

FIG. 2 schematically represents, in partial view, an extension of this machine supplemented by another wet offset printing unit.

The machine shown relates to a sheet printing machine and comprises a sheet-type paper input device 1 provided with a margin cylinder 2, two transfer cylinders 3 provided with clamps, and dust removal devices and elimination of static electricity 4 and 5 installed on both sides of the paper 1. The sheets are transferred to a blanket cylinder 12 provided with clamps and pressurized against another blanket cylinder 13 of the same diameter. The sheets pass between the blanket cylinders 12 and 13 and are printed simultaneously on both sides. The cylinders rotate in the direction indicated by the arrows. After being printed, the sheets are transported by a chain clamp system 21 on output stacks or, if necessary, to a machine to complete the printing. The main engine of the machine is designated by 22.

The blanket cylinder 12 cooperates according to FIG. 1 with four offset plate cylinders, three of these offset plate cylinders 8 are equipped, in the example considered, each with a dry offset printing plate each inked with an inking device 7 with double inkwell; the fourth offset plate cylinder 11 carries a wet offset printing plate inked by an inking device 9 with simple inkwell and fitted with a wetting device 10. All these elements 7 to 11 are installed on a mobile offset inking carriage 6.

Dry offset printing plates are typographic plates known per se and the wet offset printing plate is a hollow plate also known per se. These four offset plates represent partial drawings which are inked in different colors and the number of which corresponds to the number of colors and drawings of the first image to be printed on one side of the paper 1. This image is in particular a security background in the case fiduciary papers, in particular banknotes.

These partial drawings of different colors are brought together on the blanket cylinder 12 functioning as an offset blanket cylinder, therefore as a collecting cylinder for the partial drawings composing the multicolored image. This image is transferred to one of the sides of the paper, in the example considered on the back side, where a dry offset printing in three colors is thus obtained, supplemented by a monochrome wet offset printing.

In the case of fiduciary papers one can also use the three dry offset plate cylinders 8 to create a background in three colors, while the wet offset plate cylinder 11 represents a main design.

Of course for offset printing all cylinders plate holders mounted on the mobile carriage 6, therefore in the example considered all the four plate cylinders can also be fitted with dry offset plates.

On the other side of the machine are the elements to produce an "Orlof" image. These elements include a blanket cylinder 17, which has the same diameter as the blanket cylinders 12 and 13. This blanket cylinder 17 cooperates in the example illustrated with four color selector cylinders 16 having reliefs cut according to the contour of the areas to be printed in the respective color, they are inked in said color, each, by means of an inking device 15 with double inkwell. These elements 15, 16 are installed on a mobile "Orlof" inking carriage 14. These selector cylinders 16 are preferably made of hard material which is not likely to deform even if the relief is very fine, thus making it possible to obtain a security background made up of very fine color zones. The areas of the four colors are transferred to the blanket cylinder 17 which functions as a collection cylinder on which they are joined and by which they are transferred to a plate cylinder 20 carrying a letterpress printing plate in contact with said collection cylinder and with the blanket cylinder 13. This typographic plate represents the complete drawing of the second image to be printed in four colors on the other side of the paper. The complete image inked in the different colors is in turn transferred to the blanket cylinder 13 to apply the printing of the complete image, in particular a security background, on the front side of the paper, the back side simultaneously receives the offset image. During the simultaneous printing the two cylinders 12 and 13 serve mutually as back-pressure cylinders.

The machine further comprises a first image transmission cylinder 18 and a second image transmission cylinder 19 which transfer the same image of the colored areas of the blanket cylinder 17 in perfect register on the typographic plate cylinder 20, thus making it possible to strengthen the inking of the letterpress plate in the desired colors and therefore to better cover these areas with the desired ink. Indeed, given the direction of rotation of the blanket cylinder 17, part of the ink is transferred by the cylinders 18 and 19 to the typographic plate cylinder 20, while the rest of the ink is transferred in perfect register directly on this cylinder 20. The arrangement of the cylinders concerned for obtaining this double inking is known (DE-A-3.109.964), the second inking being offset by the length of the periphery of the typographic plate cylinder 20 or in the example considered of a third of the periphery of the blanket cylinder 17 because it has a diameter three times larger than the diameter of the cylinder 20 and carries three blankets.

In order for this register condition to be fulfilled, the arrangement of the cylinders 17,18,19 and 20 is such that the sum of the arc lengths on the peripheries of the cylinders 18,19 and 20 between the respective contact points - seen in the direction of rotation of these cylinders - must be equal to the length of the arc on the periphery of the cylinder 17 between the contact points of this one with cylinders 18 and 20 plus 1/3 of the periphery of this cylinder 17.

If the design carried on the typographic plate for the "Orlof" printing is composed only of lines, therefore very narrow inked areas, one can give up the image transmission cylinders 18 and 19 and limit oneself to an inking simple of the typographic plate "Orlof".

In the example illustrated the ratio of the diameters of the cylinders 8,11,16,18,19,20 on the one hand and of the cylinders 12,13,17 on the other hand is 1: 3; the periphery of the cylinders 12, 13 and 17 therefore corresponding to three sheets of paper, these cylinders each carry three blankets.

In the example according to FIG. 2 the printing according to the "Orlof" process is completed by a wet offset printing also carried out when the paper passes between the blanket cylinders 12 and 13, and which is used in particular to print a main design value paper monochrome. The wet offset unit comprises a hollow plate cylinder 23 provided with an inking device 24 and a wetting device 25, known per se, this hollow plate cylinder 23 cooperating with the blanket cylinder 13 which transfers the image to the paper. So in this case we obtain in a single pass on the front side a complete print, for example the security background in four colors by a print according to the "Orlof" process and the main monochrome drawings by a wet offset print, while the back side receives the security background in four colors by offset printing or a background in three colors and also a monochrome main design by wet offset printing.

The machine described can be used without problem as a web printing machine by simply replacing the means of transporting sheets by means of transporting a strip of paper which passes between the blanket cylinders 12,13.

Claims (4)

1. Multicolor rotary printing machine for simultaneous two-sided printing on a reel or a sheet, in particular for printing the security background of fiduciary papers, characterized in that it comprises a first cylinder blankets (12) in contact with several offset plate cylinders (8,11) each inked by an inking device (7.9) in a different color and the number of which corresponds to the number of colors and designs from the first image to print on one side of the paper (1), this first image being a color image and superimposed drawings, and comprising a second blanket cylinder (17) functioning as a color collecting cylinder in contact with several color picking cylinders (16) and with a typographic plate cylinder (20) representing the complete drawing of the second image to be printed on the other side of the paper (1), said selector cylinders (16), the number of which corresponds to the number e of colors of the second image and whose raised areas correspond to the parts of this image to be colored in the various colors, are each inked by an inking device (15) in a different color and apply a color image juxtaposed on said collecting cylinder, the latter in turn inking said typographic plate cylinder (20), a third blanket cylinder (13) in contact with and receiving said typographic plate cylinder (20) color image juxtaposed is in pressure with said first blanket cylinder (12), the paper (1) passing between the first and the third blanket cylinder (12,13) to be printed simultaneously on one and the other side with the first respectively the second image. 2. Machine according to claim 1, characterized in that at least one (11) of said offset plate cylinders carries a wet offset printing plate with which is associated a wetting device (10), while the other offset plate cylinders (8) carry dry offset printing plates. 3. Machine according to claim 1 or 2, characterized in that it further comprises an offset printing unit, preferably wet offset (23,24,25), the plate cylinder (23) is contact with the third blanket cylinder (13). 4. Machine according to one of claims 1 to 3, characterized in that a double inking is provided for the typographic plate cylinder (20) by means of two image transmission cylinders (18,19) .

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