EP0343104A2 - Perfecting web-fed press, particularly for bank notes - Google Patents

Abstract

The web printing machine, which is preferably intended for banknote printing, has two closely adjacent printing cylinders (2, 3), each of which interacts with several blanket cylinders (4, 6). Each blanket cylinder (4, 6) is colored by a plate cylinder (5, 7), which receives its color from its own inking unit (9, 9 '; 11, 11'). The paper web (P) runs between the impression cylinder (2, 3) and the rubber cylinder (4, 6), whereby it initially wraps around the one impression cylinder (2) and then, in the opposite sense, the other impression cylinder (3), so that both Pages of paper can be printed directly in succession with the individual colors. All rubber and plate cylinders interacting with a pressure cylinder (2, 3) are each arranged on a common, exchangeable machine frame (15, 16). In order to change the rubber and plate cylinders for cylinders with a different diameter in order to change the printing format, the machine frames (15, 16) equipped with the corresponding cylinders are replaced as a whole.

Description

The invention relates to a web printing machine for perfecting, particularly banknotes, according to the preamble of claim 1.

In a known printing press of this type, as described, for example, in EP-B 132 858 by the same applicant, the two cylinders are rubber cylinders pressed against one another, each of which is colored by several offset plate cylinders with different colors; the paper passes the printing gap between the two blanket cylinders and is simultaneously printed on both sides with a multicolor image collected on the blanket concerned. This well-known perfecting machine guarantees a perfect look-through register, that is, a perfect register of the two printed images on the front and the back of the paper, since both sides of the paper are printed simultaneously. However, the amount of ink transferred from the blanket cylinders or the thickness of the ink layers to be superimposed on a blanket cylinder is limited, a restriction that results from the operation of this known printing press.

If it is desired to print a relatively large amount of colors on the paper and if the problems associated with an overlay of different colors on a rubber cylinder are to be avoided, it must be ensured that the individual colors are printed directly on the paper and only overlap there. In a printing press operating according to this method, however, the problem of the look-through register if a perfecting is to be created. In fact, when the individual colors are applied directly to the paper, only one side of the paper can be printed on, and it is extremely difficult, if not impossible, with these known machines to print on one side and then on the other side of the paper in the sequential printing processes create and maintain a perfect review register. Even slight deviations in the correct paper position during paper transport and minimal changes in the paper tension between the two printing processes result in register errors. However, even small register errors are unacceptable in a look-through register, as is desirable for banknotes for reasons of quality and security against forgery.

Conventional web printing machines, which work with a continuous feed speed of the paper web, only allow the production of a certain printing format, which is determined by the diameter of the plate cylinders installed in the main frame.

The invention has for its object to provide a web printing machine of the type specified in the preamble of claim 1, with which a perfect look-through register is generated and maintained during printing operation and which can be converted in a simple manner to produce different printing formats, in particular different banknote formats.

According to the invention, this object is achieved by the features specified in patent claim 1.

The web printing machine according to the invention is preferably a multi-color offset printing machine, that is to say an indirectly printing machine, in which the colors are transferred from the plate cylinders to the paper in each case via rubber cylinders, one of which is colored by a plate cylinder; these rubber cylinders are mounted together with the plate cylinders in one and in the other interchangeable machine frame. The offset printing press can be a dry offset printing press working according to the indirect high-pressure process or a wet offset printing press or also a printing press partly working with high-pressure plates and partly with wet-offset printing plates.

However, the web printing machine according to the invention can also work according to the direct high-pressure method, the plate cylinders directly inking the paper without an intermediate rubber cylinder.

Since, according to the invention, the paper web is transferred directly from the first to the second, closely adjacent printing cylinder and therefore no free space has to pass through or even have to be guided by guide elements between the two printing processes, a constant paper tension and thus a perfect see-through register is advantageously ensured, since possible register errors between the perfecting and the reverse printing operation are practically excluded. In addition, there is the technical advantage that for the purpose of order position of the web press from one format to another, only the two machine frames, in which the plate cylinders or the rubber cylinders with the diameter corresponding to the format are stored, need to be exchanged for a different machine frame, the plate cylinder or rubber cylinder of which other desired format corresponding diameter. This exchange of entire machine frames, which form prepared, exchangeable cylinder modules, can be carried out much more easily and quickly than if the numerous plate cylinders or rubber cylinders had to be replaced individually in the main frame of the machine.

In order to carry out the register-based transfer of the paper web from the first to the second printing cylinder in a particularly reliable manner, the distance between the two printing cylinders can preferably be adjusted as a function of the paper thickness and has only a size necessary for the passage of the paper between the two printing cylinders, so that the transition of the paper from the first impression cylinder to the second impression cylinder takes place immediately. For example, the contact pressure between the two pressure cylinders can be at least approximately the same as the contact pressure with which a pressure cylinder and a rubber cylinder or a plate cylinder are pressed against one another when a pressure gap is formed.

Appropriate further refinements of the web printing machine according to the invention result from the dependent patent claims.

• Figur 1 eine schematische Darstellung dieser Rollen­druckmaschine nach der Erfindung und
• Figur 2 eine Ansicht eines der austauschbaren Maschi­nengestelle, wobei für den obersten Plattenzylinder die ihm benachbarten Farb- und Auftragswalzen des betreffenden Farbwerks angedeutet sind.

The invention is explained in more detail with reference to the drawings using the exemplary embodiment of a wet offset printing press. Show it :

• Figure 1 is a schematic representation of this web printing machine according to the invention and
• Figure 2 is a view of one of the exchangeable machine frames, the adjacent inking and application rollers of the inking unit in question being indicated for the uppermost plate cylinder.

In the main frame 1 of the machine, two pressure cylinders 2 and 3 are mounted side by side, which are driven in the direction of the curved arrows and whose gears are in direct engagement with one another without play in order to achieve a completely synchronous counter-rotation. Both pressure cylinders 2 and 3 have seamless, closed peripheral surfaces made of hard material, preferably of metal. Four rubber cylinders 4 are arranged along the circumference of the printing cylinder 2, each of which is in contact with a plate cylinder 5 of the same diameter. Each of these plate cylinders 5 is colored by its own inking unit, each with a different color. The three upper plate cylinders 5 include the three inking units 9 with a double ink fountain, and the lower plate cylinder 5 the inking unit 9 'with a simple ink fountain. In the example considered, it is a wet offset printing, and therefore each of the inking units 9, 9 'is assigned a dampening unit 9a. All inking units 9, 9 'with their dampening units 9a are installed on a removable inking unit frame 8 which can be moved on rollers 8a and whose moved position 8' is shown in dashed lines. The The rubber cylinder 4 and the plate cylinder 5 are mounted in an interchangeable machine frame 15 which is independent of the main frame 1.

Mirror-symmetrically to the described arrangement belonging to the pressure cylinder 2, the pressure cylinder 3 works together with four rubber cylinders 6, each of which is in contact with a plate cylinder 7 of the same diameter. In an inking unit frame 8 corresponding, on rollers 10a removable inking unit frame 10, the moved position 10 'is shown in dashed lines, are three inking units 11 with double ink fountain for coloring the three upper plate cylinders 7 and an inking unit 11' with a single ink fountain for coloring the lower plate cylinder 7 installed. A dampening unit 11a is in turn assigned to each inking unit. The rubber cylinders 6 and the plate cylinders 7 are mounted in another interchangeable machine frame 16, which is also independent of the main frame 1.

Both machine frames 15 and 16 form interchangeable plate and rubber cylinder modules.

The paper web P runs over guide and tension rollers 12 in the direction of the arrows, first wraps around the printing cylinder 2, the one side of the paper being printed directly with the individual colors during the passage between the printing cylinder 2 and the inked rubber cylinders 4, and then wrapping in the other sense the printing cylinder 3, the other paper side also being printed directly with the individual colors during the passage between this printing cylinder 3 and the inked rubber cylinders 6. The transition of the paper web P from the printing cylinder 2 to the printing cylinder 3 takes place immediately, without the paper web having a free space would have to go through, and the distance between the printing cylinders 2 and 3 is just dimensioned so large that the paper web P can pass between them. For this purpose, the distance between the two printing cylinders 2 and 3 can be adjusted as a function of the paper thickness. Due to this direct transition of the paper web from the printing cylinder 2 to the printing cylinder 3, the paper tension is kept completely constant. It is particularly advantageous if the paper web wraps around the printing cylinders as much as possible. In the example under consideration, approximately three quarters of the circumference of the printing cylinder 2 and more than half the circumference of the printing cylinder 3 are wrapped in the paper.

In order to carry out the register-based transfer of the paper web P from the impression cylinder 2 to the impression cylinder 3 in a particularly reliable manner, the contact pressure between the two impression cylinders can, for example, be at least approximately equal to the contact pressure with which a printing cylinder 2, 3 and a rubber cylinder 4, 6 form a pressure gap are pressed against each other.

The constant paper tension guarantees a perfect see-through register, which is essential for banknotes for reasons of quality and counterfeit security. Both sides of the banknote can therefore be printed at least partially with the same images and patterns and in the same colors and lie exactly on top of each other due to the perfect register created in perfecting, so that one banknote side is exactly the mirror image of the other banknote side with regard to these images and patterns , except of course the printed texts and numbers.

In the example considered, the plate cylinders 5 and 7 inked by the inking units with double ink fountains and wet offset printing plates, while the plate cylinders 5 and 7 inked by the inking units 9 'and 11' with a simple ink fountain are provided with a gravure printing plate known per se. In the case of this printing plate, the material delimiting the depressions is ink-accepting and water-repellent, while the plate surface outside the depressions consists of a water-accepting material, which is moistened by the dampening unit 9a or 11a and thus becomes ink-repellent, so that only the depressions are filled with ink during inking. In this case, the image produced by the wet offset plates on each side of the banknote preferably represents a three-color security background, while the above-mentioned gravure printing plate produces a single-color main pattern on each banknote side.

Of course, all plate cylinders 5 and 7 can also carry wet offset plates, which then in particular create a four-colored security background on each banknote side. Furthermore, it is readily possible to equip one, several or all plate cylinders 5 and 7 with a dry offset plate, that is to say a high-pressure plate, which is inked by an inking unit suitable for dry offset printing. In this way, banknotes produced in whole or in part in dry offset printing, that is to say in indirect letterpress printing, can be obtained.

Since the printing cylinders 2 and 3 have a seamless, closed peripheral surface, there is a certain ratio of the diameter of the printing cylinders 2 and 3 to the diameter of the blanket cylinders 4, 6 and the plate cylinders 5, 7, so that in order to change the printing format, the blanket and plate cylinders, the diameter of which essentially determines the format, can be exchanged for smaller or larger blanket and plate cylinders. All that is required is to replace the two machine frames 15 and 16 overall with other machine frames in which rubber and plate cylinders with a correspondingly different diameter are mounted. In the example considered, this exchange can take place after the two inking unit frames 8 and 10 have been moved away, for example with the aid of a crane.

The exchangeable machine frames 15 and 16, which are fastened and locked in their operating position on the main frame 1, preferably all have the same structure and the same size, and their bearings intended for receiving the plate and rubber cylinders are in a manner known per se, for example with With the help of eccentrics, their position can be adjusted. In this way, plate and blanket cylinders with different diameters can be installed in the same machine frames by adjusting the position of the cylinder bearings accordingly.

The arrangement is such that in the operating positions of the machine frames 15 and 16, the rubber cylinders 4 and 6 assume their correct position, in which they can be adjusted and disengaged in a known manner, that is to say they can be pressed against the printing cylinders 2 or 3 or by these for the purpose of printing operation can be moved to an out-of-service position. The position of the plate cylinders 5 and 7 is more or less depending on the diameter that they and the rubber cylinders have postponed. In order to adjust the position of the inking units 9 and 11 accordingly, as indicated in FIG. 2 for the top inking unit 9, the inking rollers 9b of the inking unit 9 in question, which are adjacent to each plate cylinder 5, in particular the inking rollers in question, including the dampening unit 9a, are known per se Adjustable way, for example on rocker arms, installed. FIG. 2 shows two different positions of these inking rollers 9b and of the dampening unit 9a for two rubber and plate cylinders of different sizes in continuous and dashed lines. In this way, the inking rollers working together with the plate cylinders can be easily adjusted in the inking unit frame depending on the diameter of the plate cylinders.

A corresponding adjustment of the operating positions of the inking unit frames 8 and 10, which can be locked in different positions, can also contribute to the correct setting of the inking units.

If necessary, the adjustable arrangement of each pair of plate cylinder 4 or 6 and blanket cylinder 5 or 7 relative to the relevant printing cylinder 2 or 3 and the inking unit in question can also be made such that when replacing a machine frame 15 or 16 with cylinders of different diameters, no particular one Readjustment of the inking units is necessary, since the exact position of the plate cylinder on the relevant printing cylinder is not important.

The range of different diameters of the plate and blanket cylinders can, for example, in relation to an average diameter, comprise up to 12% larger and up to 12% smaller diameters. Let it be use, for example, the interchangeable machine frames 15 and 16 plate and rubber cylinders, the diameter of which can be changed in stages from a minimum of 160 mm to a maximum of 200 mm.

Because of the possibility of using plate and rubber cylinders of different sizes, the pressure cylinder 2, 3 cannot of course always fulfill the otherwise usual condition that its diameter is an integral multiple of the diameter of the plate and rubber cylinders. Whenever this condition is not met, the fresh color of the image printed first on the paper from the plate cylinders 4 comes into contact with a somewhat offset circumferential area of the second printing cylinder 3 during successive rotations of the printing cylinders. It is therefore necessary to prevent the fresh ink from being transferred from the first printed paper side to the second printing cylinder 3 if the same second printing cylinder with the same surface texture is used to produce different printing formats, i.e. in connection with plate and rubber cylinders with correspondingly different diameters shall be.

For this purpose, the surface of the printing cylinder 3 preferably consists of a smooth metal layer or metal plate in the manner of a wet offset printing plate, which is moistened by a dampening unit 13. A possible ink transfer to the surface of the printing cylinder 3 is thereby avoided if the paper web P lies against the printing cylinder 3 with its previously freshly printed side. Instead of this measure, it is also possible to expose the paper web 1 lying on the printing cylinder 2 to a suitable drying device 14 after its printing and before its transition to the printing cylinder 3, which drying device is installed in the vicinity of the circumference of the printing cylinder 2 behind the rubber cylinders 4 in the direction of rotation , as indicated by dashed lines in FIG. 1. This can be, for example, drying using ultraviolet radiation. A similar drying device can also be provided in the vicinity of the circumference of the other printing cylinder 3. These drying devices are preferably combined with known cooling devices in order to obtain temperature regulation of both cylinders.

Rapidly drying inks can also advantageously be used, the drying of which may be accelerated by a drying device.

If the printing cylinder 3 has a surface like a wet offset printing plate, the surface of the other printing cylinder 2 is preferably made of metal, in particular steel. Otherwise, when working with a drying device, both printing cylinders 2 and 3 can be made of steel or have another hard surface.

As long as the condition is met that the diameter of the printing cylinders 2, 3 is an integral multiple of the diameter of the plate and rubber cylinders, for example the surface of the printing cylinder 3 can also carry a layer of chrome with a microfine grain, which is from the freshly printed paper side up takes off the color easily, so that there is a non-disturbing color balance between this chrome layer and the printed paper side lying on it. The same result can also be achieved with other surface layers that lead to such a color balance when in contact with printing inks, for example with a rubber layer of the type of offset rubber blankets.

In the example considered, the ratio of the diameter of the impression cylinders 2 and 3 to the diameter of the rubber and plate cylinders is 3: 1, which generally offers space for four colors to be applied on each side. However, the diameter ratio can also be smaller, for example 2: 1, or larger, in particular 4: 1, so that the space available on the circumference of the printing cylinders is then sufficient to, for example, three on the side in the first case and for example in the second case to apply five colors.

One of the plate cylinders on at least one side of the machine can carry an ink collecting plate, also known as an Orlof printing plate, which belongs to a collecting unit known per se, as described in EP-B 92887 by the same applicant. In this case, the collective printing plate attached to the plate cylinder, which can be a high-pressure plate in particular, is inked by an ink collecting cylinder, which in turn receives the colors from several ink selection rollers, also called stencil rollers, each inked by its own inking unit. The multicolor image of the ink collecting printing plate is then transferred through the relevant rubber cylinder 4 or / and 6 to the relevant paper page. Such a measure increases security against counterfeiting.

Optionally, the web printing machine according to the invention can also be set up to print in direct high pressure. In this case, the high-pressure plate cylinders, inked by their inking unit with one color each, are pressed directly against the printing cylinders 2 and 3, with the omission of the rubber cylinders, and print directly on the paper. For this purpose, the two pressure cylinders 2 and 3 must have a somewhat elastic surface; they then preferably wear rubber layers or rubber blankets.

Claims (14)

1. web printing machine for perfecting, particularly of banknotes, with two cylinders (2, 3) arranged side by side in the main frame (1) of the printing machine, between which the paper web (P) runs, each of these cylinders having a plurality of plate cylinders (5, 7) are assigned, which in turn are colored by inking units (9, 9 '; 11, 11'), which are installed on both sides of the printing press in two removable inking unit frames (8; 10), characterized in that the two cylinders mentioned are narrow Adjacent, seamless, closed peripheral surfaces are printing cylinders (2, 3), of which the first printing cylinder (2) in one sense and then the second printing cylinder (3) in the other sense are partially wrapped around by the paper web (P) and that between the The main frame (1) and the inking unit frames (8, 10) arranged on each side each have an interchangeable machine frame (15, 16) that is independent of these frames, in w Elchem either all the plate cylinders (5, 7) assigned to the first or second printing cylinder (2, 3) and rubber cylinders (4, 6) interacting with each of these plate cylinders, which serve as ink transfer cylinders and which color one or the other paper side, or All plate cylinders assigned to the first or second printing cylinder (2, 3), which directly ink one or the other paper side, are installed, with one side of the paper and then the other side of the paper being printed directly with the individual colors. 2. Printing machine according to claim 1, characterized in that the distance between the two printing cylinders (2, 3) is adjustable depending on the paper thickness and has only one size required for the passage of the paper web between the two printing cylinders, so that the transition of the paper web (P ) from the first impression cylinder (2) to the second impression cylinder (3). 3. Printing machine according to claim 2, characterized in that the contact pressure between the two printing cylinders (2, 3) is at least approximately equal to the contact pressure with which a printing cylinder (2, 3) and a rubber cylinder (4, 6) or a plate cylinder ( 5, 7) are pressed against each other when a pressure gap is formed. 4. Printing machine according to one of claims 1 to 3, characterized in that the interchangeable machine frames (15, 16) have the same structure and the same size as well as bearings which can be adjusted in position for the plate cylinders (5, 7) and rubber cylinders (4 , 6) or plate cylinders, in particular bearings adjustable by eccentrics, and that plate cylinders or rubber cylinders with a different diameter can be mounted therein by appropriate adjustment of these adjusted bearings. 5. Printing machine according to one of claims 1 to 4, characterized in that the inking cylinders (5, 7) adjacent to the plate cylinders (5, 7) of the inking units (9, 11), in particular the application rollers, for the purpose of adaptation to the selected diameter of the plate cylinders (5 , 7) are adjustable in their position. 6. Printing machine according to one of claims 1 to 5, characterized in that means are provided in order to prevent a transfer of fresh ink from the first printed paper side to the second printing cylinder (3) in the running direction of the paper. 7. Printing machine according to claim 6, characterized in that at least the first printing cylinder (2) in the running direction of the paper, preferably both printing cylinders (2, 3), are equipped with a drying device (14), preferably a device with temperature regulation, the Drying device (14) is arranged on the first printing cylinder (2) in the vicinity of that peripheral portion of this printing cylinder on which the freshly printed paper is located before it passes to the second printing cylinder (3). 8. Printing machine according to claim 6, characterized in that the second printing cylinder (3) in the running direction of the paper is provided with a metal plate or metal layer in the manner of a wet offset printing plate which can be moistened by a dampening unit (13). 9. Printing machine according to one of claims 1 to 5, characterized in that the second printing cylinder (3) in the running direction of the paper has a surface layer which consists of chrome with microfine grain. 10. Printing machine according to one of claims 1 to 9, characterized in that it is an offset printing machine, which according to the wet offset process or the dry offset process, that is Indirect high pressure process, works and is therefore equipped with the aforementioned rubber cylinders (4, 6) interacting with the plate cylinders (5, 7) and that both printing cylinders (2, 3) have a hard surface, at least that in the direction of the paper first pressure cylinder (2) preferably has a metallic surface, in particular made of steel. 11. Printing machine according to one of claims 1 to 7, characterized in that it is a printing machine working in direct high pressure and therefore only the plate cylinders directly coloring the paper are provided in the machine frames (15, 16) and that the printing cylinders (2, 3 ) have a somewhat elastic surface, preferably made of rubber. 12. Printing machine according to claim 10, characterized in that at least one of the plate cylinders (5, 7) carries a gravure printing plate which can be moistened by a dampening unit (9a, 11a) in order to make the surface outside the depressions to be filled with ink repellent. 13. Printing machine according to one of claims 1 to 12, characterized in that on at least one machine side one of the plate cylinders (5, 7) carries a color printing plate which can be colored in multiple colors by a printing press known per se. 14. Printing machine according to one of claims 1 to 13, characterized in that the gears of the printing cylinders (2, 3) interlock directly without play.

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