EP0343107B1 - Convertible multicolour press for perfecting, particularly for bank notes - Google Patents

Abstract

The printing machine is composed of two essentially identically constructed halves which each have an impression cylinder (4, 14), an image transfer cylinder (6, 16) resting against this, a blanket cylinder (7, 17) and a collect-printing plate cylinder (5, 15). In the offset-printing position, the blanket cylinder (7, 17) rests against the impression cylinder (4, 14) and is inked by offset plate cylinders, while the collect-printing plate cylinder (5, 15) is inoperative. In the collect-printing position, the blanket cylinder (7, 17) is moved away from the impression cylinder (4, 14), is inked by color selector cylinders (8, 18) and itself inks the collect-printing plate cylinder (5, 15) which rests against the image transfer cylinder (6, 16). Moreover, in both printing positions, the image transfer cylinder (6, 16) is inked by the plate cylinder (10, 20) of an additional single-color printing unit. The paper first loops partially round the impression cylinder (4) of the first machine half and is thereby printed directly on one side by the image transfer cylinder (6) and, in the offset-printing position, also by the blanket cylinder (7) and then loops partially round the impression cylinder (14) of the second machine half, the other side of the paper being printed in a similar way.

Description

The invention relates to a convertible multicolor printing machine for perfecting, in particular banknotes, according to the preamble of patent claim 1.

A printing press of this type is known from EP-A 0 132 859. In this known machine, the first two cylinders of each half of the machine are rubber cylinders pressed against each other, which work together as a straight printing cylinder and an impression cylinder and between which the paper to be printed is carried out with simultaneous printing on both sides. Since each of the two machine halves can either use the offset printing process or the batch printing process, this perfecting machine delivers either a multicolored offset print on both paper sides or a multicolored batch print on both paper sides or a multicolored offset print on one paper side and on the other Paper side a multi-colored collective print. This printing machine is intended in particular for the production of banknotes, the multicolored images, which are produced either using the offset printing process or the collective printing process, in particular representing a security background.

While the batch printing process delivers images with adjacent colors, the offset printing process can be used to overlay colors and partial images.

In the case of this known printing press, in the case of offset printing, the multicolor image originating from the offset plate cylinders, which is transmitted to the rubber cylinder interacting with these offset plate cylinders, is first transferred to the rubber cylinder functioning as an impression cylinder or impression cylinder before it reaches the paper from the latter. In the case of a batch print, the multicolor image of the inked batch printing plate on the batch printing plate cylinder is transferred via the image transfer cylinder, which is designed as a blanket cylinder, to the blanket cylinder, which functions as an impression cylinder or impression cylinder, before it reaches the paper from the latter. In addition, the additional printing unit in this known printing machine works together with the recto cylinder or the impression cylinder, which is inked by the plate cylinder of this printing unit.

From DE-A-435 902 and GB-A 1 559 998, perfecting machines with two central printing cylinders and an S-shaped paper guide are known, such that the paper first has one printing cylinder in one sense and then the other printing cylinder in the other sense partially wraps around. According to DE-A 435 902, in which a sheet-fed printing machine is described, the two central printing cylinders are in contact with one another for the purpose of direct sheet transfer from one to the other. Each of the two printing cylinders interacts on the one hand with a plate cylinder, which directly colors the surface of this printing cylinder, and, on the other hand, with a rubber cylinder colored by another plate cylinder, which forms a printing gap with the relevant printing cylinder. In this way, the paper receives a first perfecting when it passes through the first printing nip and then, after being taken over by the second printing cylinder, a second perfecting when it passes through the second printing nip.

In the machine described in GB-1 559 998, the paper is printed directly by a plate cylinder when it passes the first printing cylinder on one side and then when it passes the second printing cylinder on its other side. In the case of a web-fed printing press, the two printing cylinders are at a distance from one another and the paper web is stretched between the two printing cylinders. In the case of a sheet-fed printing press, the two printing cylinders are closely adjacent.

In order to at least partially dry the ink freshly applied to a paper web wrapping around a printing cylinder before this paper web receives further printing, it is known from FR-A-2 315 389 to provide a drying device along part of the circumference of the printing cylinder.

The present invention is based on the object of improving a convertible printing machine of the type described in the preamble of claim 1 in such a way that the number of color transfers required to transfer the color from the offset plate cylinders or from the collective printing plate cylinder to the paper is reduced , and that from the additional printing unit provided in at least one of the machine halves, a further single-color image is applied to the relevant paper page.

This object is achieved according to the invention by the features specified in claim 1.

The additional printing unit can be a dry offset printing unit or, preferably, a wet offset printing unit, which works in particular with a moistened rotogravure plate.

The convertible printing machine according to the invention has the advantage that, both in offset printing and in batch printing, the rubber cylinder colored by the offset plate cylinders or the image transfer cylinder colored by the printing plate cylinder transfers the multicolor image directly to the relevant paper side, so that a color image transfer between blanket cylinders is eliminated. First, one side of the paper and then the other side are printed. With the additional printing unit, a further single-color image can also be applied to one of the two sides or to both sides of the paper in a single pass, banknote printing in particular being a main pattern.

Although both sides of the paper are printed one after the other, a practically perfect perfecting and counterprint register can be achieved, because the printing cylinders, which work together as a straight printing cylinder and an impression cylinder, are closely adjacent and the paper is transferred directly from one to the other printing cylinder, so that a direct paper transfer without additional Transfer organs is guaranteed. The arrangement is preferably such that the distance between the two pressure cylinders can be adjusted according to the paper thickness and is selected such that the contact pressure is at least approximately equal to the contact pressure with which a pressure cylinder and a rubber cylinder are pressed against one another when a pressure gap is formed. This ensures the perfect transfer of the paper, especially in sheet form, from one to the other printing cylinder with certainty.

• Figur 1 eine Ausführungsform der Druckmaschine, bei der beide Maschinenhälften ihre Sammeldruckstellung einnehmen, und
• Figur 2 die gleiche Druckmaschine mit beiden Maschinenhälften in der Offsetdruckstellung.

The invention is explained in more detail with reference to the drawing using the exemplary embodiment of a sheet-fed printing press. Show it :

• Figure 1 shows an embodiment of the printing press, in which both halves of the machine assume their collective printing position, and
• Figure 2 shows the same printing press with both press halves in the offset printing position.

The printing press consists of two machine halves which, with the exception of the devices which feed the paper and the devices which lead the paper out of the machine, are constructed essentially the same. Each machine half has a printing cylinder 4 or 14, a printing plate cylinder 5 or 15, an image transfer cylinder 6 or 16 and a blanket cylinder 7 or 17. Each blanket cylinder 7 or 17 is colored by convertible cylinders 8 or 18, which are offset plate cylinders in the case of offset printing and color selection cylinders in the case of collective printing, and which are each colored by their own inking unit 9 or 19 with a different color will. All inking units 9 are installed in an inking unit carriage 12 and all inking units 19 are installed in an inking unit unit 22.

In addition, in the example considered, each machine half has an additional single-color printing unit, the plate cylinder 10 or 20 of which rests on the image transfer cylinder 6 or 16 and is inked by its own inking unit 11 or 21. This additional single-color printing unit is an offset printing unit, preferably, as indicated in FIGS. 1 and 2, around a wet offset printing unit which works with a dampening unit 11a or 21a. An intaglio printing plate is preferably used as the wet offset printing plate, the non-printing surface of which is made ink-repellent by the moistening. The inking unit 11 and the dampening unit 11a are accommodated in an inking unit frame 13, which is arranged on the top of the inking unit carriage 12. The inking unit 21 and the dampening unit 21a on the other side of the machine are accommodated in an inking unit frame 23 which is arranged on the upper side of the inking unit carriage 22.

The pressure cylinders 4, 14 and the blanket cylinders 7, 17 rotate in the direction of the arrows. The paper 1 in sheet form is fed via a stop drum 2 and transfer drums 3 provided with grippers, passes paper dedusting and antistatic devices 3 'arranged on both sides, is then taken over by the printing cylinder 4 acting as an impression cylinder, on which it is held by grippers, and wraps around this pressure cylinder 4 on its lower half in the figures; after the paper has passed the gap between the two printing cylinders 4, 14, it is taken over by the grippers of the printing cylinder 14, which acts as an impression cylinder, and now wraps it around most of its circumference in the other sense, until it finally reaches the lower area of the printing cylinder 14 a chain gripper system 24 is taken over and led out of the printing press.

The rubber cylinders 7 and 17 are between a collective printing position shown in FIG. 1, in which they have moved away from the relevant printing cylinder 4 and 14, respectively an offset printing position shown in FIG. 2, in which they are pressed against the relevant printing cylinder 4 or 14, adjustable.

In the collective printing position shown in FIG. 1, the collective printing plate cylinder 5 or 15 assumes its working position, that is to say that it lies against both the respective rubber cylinder 7 or 17 and the relevant image transfer cylinder 6 or 16 and carries a collective printing plate which has a complete printing pattern, which is preferably a high-pressure plate. The convertible cylinders 8 and 18 carry color selection plates. These color selection plates have cut-out reliefs which correspond to the areas of the printing plate to be printed in a specific color, and transfer a multicolor image with adjacent colors to the rubber cylinder 7 or 17, which acts as the ink collecting cylinder, which in turn colors the printing plate cylinder 5 or 15. The multicolor image is transferred from the colored printing plate to the image transfer cylinder 6 or 16, which is a rubber cylinder. At the same time, in the example under consideration, this image transfer cylinder 6 or 16 also receives the additional print image from the plate cylinder 10 or 20 of the additional single-color printing unit.

In each half of the machine, image transfer cylinders 6 and 16 and impression cylinders 4 and 14 each form a printing gap between them. The paper 1 first passes through the printing nip in the first half of the machine with printing on one side and then through the printing nip in the second half of the machine where it is printed on its other side.

In the offset printing position shown in FIG. 2, the printing plate cylinder 5 or 15 assumes its moved out of operation position, the rubber cylinder 7 or 17 is pressed against the printing cylinder 4 or 14, and the convertible cylinders 8 and 18 carry offset printing plates, the partial images of which on the Rubber cylinders 7 and 17 are transmitted.

In this offset printing position, each machine half has two printing nips, namely a first printing nip between printing cylinder 4 or 14 and image transfer cylinder 6 or 16, which in this case only receives the print image from plate cylinder 10 or 20 of the additional single-color printing unit, and a second printing nip between printing cylinder 4 or 14 and blanket cylinders 7 or 17. The paper 1 passes in succession in both machine halves, first on the impression cylinder 4, then on the impression cylinder 14, in each case through the first and second printing nips, with first one paper side and then the other paper side in each case receive single-color printing and multi-color offset printing.

Since the two printing cylinders 4 and 14 are closely adjacent and the paper sheets are thereby transferred directly from one to the other printing cylinder, without additional paper guiding means, a practically perfect plate-back printing register is ensured despite the successive printing. In order to ensure with certainty that the paper is transferred from the printing cylinder 4 to the printing cylinder 14 in register, the distance between the two printing cylinders can be adjusted according to the paper thickness and is preferably chosen so that the contact pressure is at least approximately equal to the contact pressure with which a pressure cylinder 4 or 14 and the respective rubber cylinder 7 or 17 are pressed against one another to form a pressure gap.

In the example considered, the impression cylinders 4, 14 and the blanket cylinders 7, 17 are of the same size and have a diameter which is a multiple, in the example considered three times, the diameter of the printing plate cylinders 5, 15, the image transfer cylinders 6, 16, and the plate cylinder 10 , 20 and the convertible cylinder 8, 18. The two rubber cylinders 7, 17 are lower than the pressure cylinders 4, 14 and are each offset obliquely outwards with respect to these; the printing plate cylinders 5, 15 and the image transfer cylinders 6, 16 are located above the rubber cylinders 7, 17. In this way, the entire area below the rubber cylinders 7, 17 and the printing cylinders 4, 14 is free from inking cylinders and is therefore easily accessible.

Since the diameter of the printing cylinders 4, 14 is an integral multiple of the diameter of the plate cylinders 8, 18, the fresh color images printed on the first paper side always come into contact with the same circumferential sections of this printing cylinder 14 during each revolution of the second printing cylinder 14. Therefore, possible color transfers from the freshly printed first paper page to the second printing cylinder 14 are in principle not disruptive, because the color patterns possibly transferred with each rotation of the printing cylinder 14 coincide.

However, in order to rule out possible impairments of the print quality as a result of such color transfers, it can be ensured that color transfer from the freshly printed paper side to the second printing cylinder 14 does not take place. For this purpose, as indicated in the figures, in the vicinity of the peripheral portion of the first printing cylinder 4 covered by the freshly printed paper, a drying device 25 can be provided, which dries the fresh printing ink before it comes into contact with the surface of the second printing cylinder 14. A similar drying device can also be installed on the second pressure cylinder 14. These drying devices are expediently equipped with a device for temperature regulation. Rapid drying inks can also be used and a drying device 25 can be used to accelerate this drying.

Another way to avoid ink transfer from the freshly printed first paper page to the second printing cylinder 14 is to provide this printing cylinder 14 with an at least approximately ink-repellent surface, which consists, for example, of a metal layer in the manner of a wet offset printing plate, which is produced by a dampening system is moistened.

However, as already mentioned, a certain amount of ink transfer to the surface of the second printing cylinder 14 can be accepted, but duplication should then be avoided by covering the second printing cylinder 14 with offset rubber blankets, the first printing cylinder 4 has a hard surface and, as mentioned, both printing cylinders are pressed so strongly against one another that the sheets are clamped in and are correctly guided during the transition from one printing cylinder to the other. At the same time, excessive ink accumulation on the rubber surface of the second printing cylinder is avoided because a color balance is established between the rubber and the paper. It is also possible to provide a layer of chrome with microfine grain on the surface of the printing cylinder 14, which easily releases the ink absorbed by the freshly printed paper side, so that there is a non-disturbing color balance between this chrome layer and the printed paper page lying on it.

While the first printing cylinder 4 in the direction of the paper, i.e. the face printing cylinder, in all cases preferably has a hard surface, in particular a metallic surface, for example made of steel, the choice of the surface of the second printing cylinder 14, i.e. the impression cylinder, depends on the direction of the paper , depending on whether and if so which means are provided to prevent ink transfer to this printing cylinder. When working with a drying device 25, as mentioned, or with a quick-drying ink, the second printing cylinder 14 can have the same hard surface, in particular made of steel, as the first printing cylinder 4. If the surface of the second printing cylinder 14 is made color-repellent then, as mentioned, it has a surface layer like a wet offset printing plate. If ink transfers to the second printing cylinder 14 are permitted, then, for example, a blanket surface can be used, as mentioned or provide a chrome layer with microfine grain.

In the example under consideration, the two blanket cylinders 7 and 17 and also the second impression cylinder 14, which is assumed to be covered with blankets, are each equipped with a detachable automatic blanket washing device 26, which of course has moved away from the cylinders during printing operation. When using a second printing cylinder 14 covered with rubber blankets, the drying device 25 can be omitted.

Of course, the printing press described can also be operated in such a way that one machine half assumes its offset printing position and the other machine half assumes its collective printing position. Also, only one of the two machine halves can be equipped with an additional single-color printing unit. On the other hand, it is possible to provide one or more further single-color printing units along the free circumferential sections of the printing cylinders 4 and 14, the images of which are transferred directly to the relevant paper page via an image transfer cylinder with an elastic surface.

In banknote printing, the multicolor offset printing or collective printing images preferably represent the security background, while the additional single-color printing units with the plate cylinders 10 and 20, which are designed as wet offset printing units, provide a main pattern. In addition to the main pattern, the plate cylinders of these additional printing units can also have a further printing pattern which supplements and possibly overlaps the multicolored security background have a security surface.

In addition to the advantage that the colors or the images are transferred directly from the plate cylinders to one or the other side of the paper via only one rubber cylinder, the printing machine according to the invention is characterized in that it bills banknotes with a high level of security against counterfeiting printing allowed. This high level of security against counterfeiting is achieved, on the one hand, by the fact that the multicolored security background on one banknote side can be produced using a different printing process than that on the other banknote side, and furthermore the main pattern can in turn be produced on each banknote page using a different printing process, namely the wet offset printing process, and that, on the other hand, with the help of an additional background pattern on the printing plates of the additional single-color printing units, a very complicated security background composed of overlapping lines can be produced.

The printing press described can also be designed as a web printing press, in which case the sheet guiding members are simply replaced by the known guiding members for a paper web and, if continuous printing operation is provided, the two printing cylinders 4 and 14 each have a continuously smooth, joint-free surface.

Claims (11)

1. Convertible multi-colour printing machine for the recto-verso printing of especially banknotes, with two essentially identically constructed halves, each comprising

   - a first cylinder (4, 14),

   - an image transfer cylinder (6, 16) Pressed against this,

   - a second cylinder designed as a blanket cylinder (7, 17) and adjustable between an offset-printing position pressed against the first cylinder (4, 14) and a collect-printing position moved away from this,

   - several convertible cylinders (8, 18) which are in contact with this blanket cylinder (7, 17) and which are designed as offset plate cylinders in the offset-printing position and as colour selector cylinders in the collect-printing position and can each be inked by an inking unit (9, 19), and

   - an adjustable collect-printing plate cylinder (5, 15) which is assigned to the blanket cylinder (7, 17) and which, in the offset-printing position, can be moved away from the blanket cylinder (7, 17) into an inoperative position and, in the collect-printing position, interacts both with the blanket cylinder (7, 17) and with the image transfer cylinder (6, 16),

   - an additional printing unit in at least one of the machine halves, said additional printing unit having a plate cylinder (10, 20) inked by its own inking unit (11, 21),

   characterized by the fact that the first two cylinders (4, 14) of each machine half function as impression cylinders located closely adjacent and next to one another, that the impression cylinder (4, 14) and the image transfer cylinder (6, 16) of each machine half form a first printing nip between them, that, in the offset-printing position, the impression and blanket cylinders (4, 7; 14, 17) pressed against one another form a second printing nip between them, that the paper (1) to be printed first loops partially round one impression cylinder (4) in one direction and, after passing through the nip between the two impression cylinders (4, 14), loops partially round the other impression cylinder (14) in the other direction, the paper passing through the nips in the two machine halves, thereby being printed first on one side of the paper and then on the other, and that the plate cylinder (10, 20) of the additional printing unit inks the image transfer cylinder (6, 16).
2. Printing machine according to Claim 1, characterized by the fact that the additional printing unit is a dry offset printing unit.
3. Printing machine according to Claim 1, characterized by the fact that the additional printing unit is a wet offset printing unit which works particularly with a dampened intaglio printing plate.
4. Printing machine according to one of Claims 1 to 3, characterized by the fact that the distance between the two impression cylinders (4, 14) is adjustable and preferably selected so that the pressing force is at least approximately equal to that pressing force with which an impression cylinder (4; 14) and a blanket cylinder (7; 17) are pressed against one another to form a printing nip.
5. Printing machine according to one of Claims 1 to 4, characterized by the fact that the impression cylinder (4) which is the first in the direction of run of the paper has a hard surface, preferably a metallic surface, for example of steel.
6. Printing machine according to one of Claims 1 to 5, characterized by the fact that at least the impression cylinder (4) which is the first in the direction of run of the paper (1) is equipped, in the vicinity of its circumferential portion covered by freshly printed paper (1), with a drying device (25), preferably with temperature regulation.
7. Printing machine according to Claim 6, characterized by the fact that the impression cylinder (14) which is the second in the direction of run of the paper has a hard surface, preferably a metallic surface, for example of steel.
8. Printing machine according to one of Claims 1 to 6, characterized by the fact that it is designed as a sheet-fed printing machine and that the impression cylinder (14) which is the second in the direction of run of the paper (1) is covered with offset rubber blankets, whilst the first impression cylinder (4) preferably has a hard surface, and that the two impression cylinders (4, 14) rest against one another with a pressing force sufficient for register guidance of the sheets.
9. Printing machine according to one of Claims 1 to 6, characterized by the fact that the impression cylinder (14) which is the second in the direction of run of the paper (1) has an at least approximately ink-repellent surface which is composed, for example, of a metal layer in the manner of a wet offset printing plate, dampenable by means of a dampening unit, or a surface of chromium with a micro-fine grain.
10. Printing machine according to one of Claims 1 to 9, characterized by the fact that the impression cylinders (4, 14) and the blanket cylinders (7, 17) are of equal size and have a diameter which is an integral multiple of, preferably three times, the diameter of the collect-printing plate cylinders (5, 15), of the image transfer cylinders (6, 16), of the convertible cylinder (8, 18) and, if appropriate, of the plate cylinders (10, 20) of the additional printing unit, that the two blanket cylinders (7, 17) are located lower than the impression cylinders (4, 14) and are respectively arranged offset obliquely outwards in relation to these, that the collect-printing plate cylinders (5, 15), the image transfer cylinders (6, 16) and, if appropriate, the plate cylinders (10, 20) of the additional printing unit are located above the blanket cylinders (7, 17) and the underside of the impression cylinders (4, 14) is free of inking cylinders.
11. Printing machine according to one of Claims 1 to 10, characterized by the fact that the offset plates on the offset plate cylinders or the collect-printing plate on the collect-printing plate cylinder in at least one of the machine halves have the respective multi-colour printing designs for the safety background, and the single-colour printing plate of the additional printing unit has a main design and if appropriate, in addition to this main design, a further safety-background design supplementing and preferably superposed on the multi-colour safety background.

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