Device in a sheet-fed offset printing press for printing onto printed sheets

Abstract

In order to print bar codes, serial numbers or the like onto single- or multi-colour printed sheets by means of inkjet printers, according to the invention the printed sheets, immediately after the printing process, are guided by means of a sheet guide path (28) past one or more inkjet printers arranged perpendicularly to the sheet guide path (28). The printed sheets are conveyed, without grippers, along the sheet guide path and in contact therewith. In order to carry out the method, an intermediate module (28) having two endless chain conveyors and a plurality of suction belt conveyors (29) is arranged between printing units (20, 21) in a sheet-fed offset printing press (1).

Description

[0001] DEVICE IN A SHEET-FED OFFSET PRINTING MACHINE FOR IMPRESSING INTO PRINTED SHEETS

[0002] The invention relates to a method for imprinting codes, text or image elements with inkjet printers into already printed sheets and to a device for carrying out the method according to claim 1.

[0003] For various applications, print media must be individually marked after single- or multi-color printing with identical print images, for example with a barcode, consecutive numbering or recipient addresses. This previously required a separate printing process. With the inkjet printers that have now been developed and are now commercially available, it is possible to carry out the individual marking directly after the actual printing process, i.e. the marking can be applied contactlessly to the print media, which is moving at normal printing speed. The print image produced with them can be applied at a sufficiently high speed and changed quickly enough from print media to print media. However, a prerequisite for perfect print quality is that the distance between the print media and the inkjet printer is precisely maintained.This requirement is met when the printing medium is guided through the printing press as a ribbon, because the printing medium can be pulled by means of the ribbon tension over a fixed or rotating guide which is arranged at a fixed distance from the inkjet printer.

[0004] However, if the printing media are individual sheets, this requirement can only be met if the print image is dry and smear-resistant and if brushes and / or pressure rollers can be used to stabilize the distance. These ensure that the print sheet is pressed against a sheet guide drum precisely positioned opposite the printers in the printing area for subsequent marking. This is not possible with a sheet that is still freshly printed, as the guide means would smudge the print image. Since in sheet-fed printing presses the print sheet is only held by grippers at the start of printing and otherwise only rests loosely on the printing or guide cylinder, the distance to an inkjet printer that is fixed to the housing can often not be reliably maintained. Thin print media tend to slide together on the cylinder, while thicker print media lift off the cylinder due to their own tension.Furthermore, the distance between the printed sheet and the printer must not only be precisely maintained in the area of ​​the individual marking to be applied, but it must also be ensured that the printed sheet does not touch the printer over its entire length during the run and possibly damage it.

[0005] From DE-C 25 01 793 an inkjet printer is known by means of which a moving material web (paper web) can be printed.

[0006] From DE 92 10 569 U a sheet-fed printing machine is known with a sheet transfer drum connected downstream of a printing unit, which interacts with a turning drum by means of which the printed sheets transferred from the sheet transfer drum to the turning drum are turned.

[0007] Domino Amjet GmbH's German company brochure "The Domino Program for the Graphic Industry" describes a sheet-fed printing press in which inkjet print heads are assigned to a printing cylinder. Printing on the sheets takes place on the impression cylinder of the respective printing unit immediately after the sheets have been printed.

[0008] EP 0 737 572 A1 discloses a method for imprinting barcodes into printed sheets and a device for carrying out the method. To imprint barcodes, numbering, or the like onto single- or multi-color printed sheets using an inkjet printer, it is proposed that, immediately after printing, the printed sheets be guided by a sheet guide drum past one or more inkjet printers arranged radially to the sheet guide drum, while the sheet end is held firmly against the sheet guide drum. For this purpose, the sheet guide drum is arranged in the sheet-fed printing press between the printing units or printing units and the delivery. The printed sheets are guided and taut using rows of grippers and suction cups arranged for each row of grippers. An inkjet printer is arranged radially to the sheet guide drum.

[0009] EP 1 818 177 B1 discloses a sheet-fed rotary printing press in unit and series design with a sheet feeder, downstream printing, coating or drying units, and a sheet delivery. A separate sheet guiding unit contains an inline sheet inspection device for scanning the surfaces of printed sheets within a scanning area, or a marking device for applying markings to the printed sheets in a marking area. The sheet guiding unit's sheet-guiding section is designed to match the dimensions and connection configuration of the other printing, coating, or drying units, so that it can be arranged upstream or downstream of any printing press unit as a separate module. It has a sheet-guiding drum with a cylindrical outer surface on which the scanning or marking area is located.The drum has means for fixing the printed sheets on the outer surface at the leading edge of the sheet and in a further area.

[0010] DE 39 36 345 CI discloses a sheet-fed printing press for multi-color printing, in which gripper carriages are guided wave-like through the printing units on endless chains and are mechanically synchronized with the respective impression cylinders. The impression cylinders have a diameter twice that of the plate and blanket cylinders. Attached to the ends of the double-sized impression cylinders are sprockets, also double-sized, on which two diametrically opposed fixing devices are arranged, adjustable in both radial and tangential directions. In the multi-color printing press, the sheets to be printed are separated from a stack in a feeder and fed to a gripper carriage in a first printing unit, with each sheet being gripped by a gripper carriage at the leading edge by grippers.The gripper carriage then guides the printed sheet through all printing or processing units without changing the gripper closure to a delivery unit, where the printed sheet is laid out on a stack.

[0011] The invention is based on the object of creating a device for producing impressions using an inkjet printer, which can also print on freshly printed sheets without any loss of quality.

[0012] The solution to the problem is carried out with the features of claim 1. Advantageous further developments emerge from the subclaims.

[0013] A method is provided for imprinting code, text, or images using inkjet printers into printed sheets printed in one or more colors using a sheet-fed offset printing press. Immediately after processing or treatment in a printing unit or processing unit, the printed sheets are guided past one or more inkjet printers arranged in the sheet-guiding unit by means of a sheet-guiding unit and fed to a further printing unit or processing unit. According to the invention, the printed sheets are transferred in the sheet travel direction from the first printing unit from a gripper closure in grippers in conjunction with a printing cylinder, directly or indirectly, to a sheet guide track provided with a substantially flat guide surface in the sheet-guiding unit.

[0014] The printed sheets are then taken over from the gripper closure by one or more conveyor devices without gripper closure and guided firmly over a flat guide area of ​​the sheet guide track.

[0015] The printed sheets are then guided past the inkjet printer(s) and printed. The printed sheets are fed directly or indirectly from one or more conveyors without gripper closures to a device with gripper closures assigned to the second printing unit or processing unit.

[0016] Finally, the printed sheets are transported further by the second printing unit or processing unit in the gripper closure and removed by the conveyor system and the sheet guide track.

[0017] Advantageously, the printed sheets in the sheet guiding unit are aligned and / or tightened in the transport plane with respect to their leading and / or one side edge by means of the conveyor devices for gripperless transport in the sheet travel direction and / or transversely thereto.

[0018] Advantageously, each printed sheet in the sheet guiding unit is braked by means of the conveyor devices for gripperless transport in the sheet travel direction before printing with the inkjet printer(s) and accelerated again by the conveyor devices after printing with the inkjet printer(s).

[0019] For this purpose, a sheet-fed offset printing press is used, which includes a sheet feeder, several printing units and / or processing units with sheet-guiding printing cylinders downstream of the sheet feeder, a sheet guiding unit arranged between the printing cylinders of the printing units and / or processing units, and a sheet delivery unit arranged downstream of the printing units and processing units. One or more inkjet printers are arranged in the area of ​​one or more of the sheet guiding units.

[0020] According to the invention, the sheet guiding unit is designed as an intermediate module, and a sheet guide path extending essentially flat in the sheet travel direction is arranged in the intermediate module. Means for gripperless transport of the printed sheets along the sheet guide path are assigned to the sheet guide path. The inkjet printer(s) are arranged essentially perpendicularly relative to a flat guide area of ​​the sheet guide path.

[0021] Advantageously, each of the printing cylinders of the printing units or processing units adjacent to the intermediate module is assigned an endless chain conveyor guided along two chain guide tracks. Each chain conveyor is equipped with three or more gripper carriages for transporting printed sheets by means of grippers and is arranged parallel to the sheet guide track in an area where the printed sheets are moved by gripper systems.

[0022] Advantageously, the sheet guide path is formed from a first flat guide area, a second flat guide area, and a third curved guide area. The first flat guide area extends tangentially from a transfer point on the first printing cylinder of the first printing unit or processing unit to the second flat guide area, which forms a printing area in conjunction with the inkjet printers. The third curved guide area adjoins the second flat guide area seamlessly and is designed to curve upwards in the sheet travel direction, so that it tangentially approaches the surface of the second printing cylinder in the second printing unit or processing unit at a transfer point.

[0023] Advantageously, the first endless chain conveyor is arranged in the first flat guide area, extending tangentially away from the first printing cylinder and guided parallel to the sheet guide path. The second endless chain conveyor is arranged in the third curved guide area, approaching tangentially to the second printing cylinder and guided parallel to the sheet guide path.

[0024] Advantageously, the sheet guide track is provided with openings for the passage of grippers on the gripper systems. The first endless chain conveyor in the first flat guide section is arranged in the area parallel to the sheet guide track in such a way that the grippers are guided through the openings. The second endless chain conveyor is arranged in the third curved guide section in the area parallel to the sheet guide track in such a way that the grippers are guided through the openings. Advantageously, two or more suction belt conveyors are arranged in the intermediate module parallel to the sheet guide track and oriented in the direction of sheet travel, symmetrical to the width alignment of the sheet guide track. These are arranged in openings in the sheet guide track in such a way that suction belts, which can be subjected to negative pressure via suction chambers, contact the underside of printed sheets lying on the sheet guide track.The suction belt conveyors extend in the sheet travel direction at least from the center of the first flat guide area in the area of ​​the parallel guide of the endless chain conveyor on the underside of the sheet guide track to beyond the second flat guide area.

[0025] Advantageously, the two or more suction belt conveyors arranged in an intermediate module parallel to the sheet guide path are provided with at least one drive for generating a conveying movement via the suction belts. The drives can be coupled individually, in groups, or jointly to all suction belt conveyors. The suction belt conveyors can therefore be controlled individually, in groups, or jointly with respect to their conveying movement with respect to sheet transport through the sheet-fed offset printing press.

[0026] Advantageously, the two or more suction belt conveyors arranged in an intermediate module parallel to the sheet guide path are provided with a control system for a suction air supply to generate a vacuum in the suction chambers for the suction belts. With regard to sheet transport through the sheet-fed offset printing press, the vacuum supply to the suction belt conveyors can be implemented individually for each suction belt conveyor, for groups, or for all suction belt conveyors together. The vacuum supply within each of the suction belt conveyors can also be designed to be zonally controllable in the sheet travel direction.

[0027] Advantageously, the intermediate module with the inkjet printers is arranged between two printing units, or between a printing unit and a processing unit, or between two processing units, or between a last printing unit and a sheet delivery unit, or between a processing unit and a sheet delivery unit.

[0028] During a printing process in a sheet-fed offset printing press, the sheets to be coded or coated are guided in a flat alignment past one or more essentially vertically arranged inkjet printers by means of a sheet guiding device, immediately after printing in the printing units or between two printing or processing operations. The printed sheets are transported flat and tightly against the sheet guiding device by means of interacting chain conveyors and suction belt conveyors.

[0029] In this way, each printed sheet is pressed against the sheet guide along its entire length. It cannot lift off the sheet guide or slide along it. This limits the distance changes between the print substrate and the inkjet printer to differences in the thickness of the printed sheets or unevenness of the sheet guide. However, both influencing factors can generally be kept so small that the quality of the print image produced by the inkjet printer cannot be compromised.

[0030] This arrangement is extremely space-saving and can easily be retrofitted to existing sheet-fed printing presses. It allows for personalized markings to be applied to the sheets immediately after the actual printing process, without requiring intermediate sheet storage and without reducing the normal printing speed. Modern printing presses can print 15,000 to 18,000 sheets per hour in multiple colors, corresponding to a throughput speed of 180 to 220 m / min. Inkjet printers for applying personalized markings can operate at 200 m / min and achieve almost the same print quality as laser printers.Even 600 m / min are possible if the individualizing marking is relatively simple, such as a barcode running in the direction of travel, or if the highest print quality is not required for the marking.

[0031] To ensure that the personalized marking can be applied anywhere on the printed sheet, the inkjet printer is mounted within the housing using guides and rollers that can be adjusted parallel to the axis of the sheet guide drum. This allows the marking to be positioned transversely to the sheet travel direction. Positioning in the sheet travel direction is controlled by a control system for the inkjet printer connected to the printing press. Finally, the distance between the inkjet printer and the sheet guide drum is adjustable to accommodate sheets of varying thickness.

[0032] According to the invention, a modular sheet transport system in a sheet-fed offset printing press is designed so that a digital printing system with inkjet printers can be adapted instead of a sheet transport drum. The modular design of the sheet-fed offset printing press, with identical and variably connectable unit components, is retained. The integration of inkjet printing does not require any specifically modified special modules that would have to be manufactured from printing, coating, transfer, drying, or other printing press units.

[0033] The use of a flatbed version of a printing table for inkjet printing, which is not based on a cylindrical shape, is particularly advantageous. This allows for the arrangement of multiple inkjet print heads in front of and behind each other. Sheet guidance eliminates the need for complex sheet guide drums in the form of so-called storage drums, which require complex rotary joints for operating materials and power supply.

[0034] The concept also eliminates the need for specific sheet transfer drums or sheet guiding devices in the form of complex fan tracks with multiple air supply.

[0035] A combination of sheet transport using gripper systems and suction belts can meet all transport requirements. At least one suction belt is required, but two or more suction belts are preferred.

[0036] No complex additional systems are required to control the flat guidance of the sheet trailing edges. In this context, no complex format adjustment is necessary for sheet transport with different sheet sizes.

[0037] Since no additional sheet guide cylinders are required for sheet transport within the inkjet printer range, the device is simple. This provides good access directly from above to the inkjet printer area for operation, cleaning, and maintenance.

[0038] In addition, an air-operated sheet guide table can be used for stable and smear-free sheet guidance.

[0039] For sheet transport during gripper closure, separate chain conveyors with at least three gripper systems are used on each printing cylinder involved. This essentially simulates the function of a triple-sized sheet transport cylinder on a double-sized printing cylinder. Chain conveyors with more than three gripper systems can also be used.

[0040] The chain conveyors guide the gripper systems around their respective printing cylinders and fix the gripper systems in the cylinder channels.

[0041] Further details are explained in more detail using an example embodiment shown in the drawing.

[0042] Figure 1 shows a first embodiment according to the prior art,

[0043] Figure 2 shows a second embodiment according to the prior art,

[0044] Figure 3 is a schematic elevation of a device according to the invention,

[0045] Figure 4 is a plan view of a device according to the invention,

[0046] Figure 5 is a representation according to Figure 3 with transfer situations in a device according to the invention and

[0047] Figure 6 shows a gripper system on a feeding printing unit in a device according to the invention.

[0048] Figure 1 shows, in the prior art, a simplified representation of a partial section through the area of ​​a sheet-fed printing press 1, where a delivery system 2 is connected downstream. There, a sheet guide drum 3 with two rows of grippers 4 is drivably mounted in a housing 5. The sheet guide drum 3 receives freshly printed sheets from a printing cylinder 13 of a last printing unit 15 via an intermediate drum 14. In the sheet guide drum 3, two rows of suction heads 6 are arranged in the circumferential direction relative to the grippers 4, which can be adjusted by motor or manually so that the beginning of the sheet is grasped by the grippers 4 and the end of the sheet can be held firmly against the sheet guide drum 3.

[0049] The device further comprises two inkjet printers 7, 8, which are adjustable parallel to the axis of the sheet guide drum 3 in the housing 5 by means of guides 9 and rollers 10 engaging therein. Radial adjustment of the inkjet printers 7, 8 to regulate the distance from the sheet guide drum 3 or to adapt to different sheet thicknesses is also possible.

[0050] The sheet guide drum 3, together with the intermediate drum 14, is arranged in an intermediate module 18 adjacent to the printing unit 16 and the delivery system 2. The intermediate module 18 also houses the inkjet printers 7, 8 associated with the sheet guide drum 3.

[0051] Instead of the suction heads 6, a device 11 for electrostatically charging the sheet guide drum 3 and / or the printed sheets can also be provided, which is preferably arranged in the transfer area of ​​the printed sheets onto the sheet guide drum 3. This includes a device 12 for electrostatically discharging the printed sheets in the area of ​​the delivery system 2, so that the printed sheets can be delivered from the sheet-fed printing press 1 without disruptive electrostatic charging. Figure 2 shows an alternative design known in the prior art, according to which the assembly comprising the sheet guide drum 3 and the inkjet printer 7, 8 is arranged between printing cylinders 13 of two printing units 16, 17. For this purpose, the assembly can be connected to the printing units 16, 17 as an intermediate module 19 with intermediate drums 14 and can thus be positioned anywhere in the sheet-fed printing press 1 depending on the requirements for a specific machine configuration.

[0052] Figure 3 shows an embodiment of the invention in elevation. For clarity, the scale of an intermediate module 25 of the device according to the invention is shown enlarged with respect to the transport paths of the printed sheets D to be conveyed compared to the transport path on printing cylinders 23, 24 in adjacent printing units 20, 21.

[0053] In this case, the intermediate module 25 replaces a conventional sheet transport module, but does not have to meet its installation space requirements, since the sheet transport is not tied to cylinders or drums.

[0054] A sheet transport module can be formed by one or more sheet guiding cylinders and is arranged between the printing cylinders of two printing or processing units or between the sheet guiding cylinder (impression cylinder) of a last printing or processing unit and a sheet guiding cylinder of a delivery.

[0055] If the length of the intermediate module 25 corresponds to the length of each of the printing units 20, 21 in relation to the space required by their printing cylinders 23, 24, the intermediate module 25 can be used in a sheet-fed offset printing press in place of a normal printing press module (such as printing units, coating units, drying units, perfecting units) (see also the last section after the description of Figure 6).

[0056] Here, two known printing units 20, 21 are shown within a sheet-fed offset printing press, wherein a first printing unit 20, in addition to a cylinder group 22 consisting of a forme or plate cylinder and a blanket or rubber cylinder, also has a first sheet-guiding impression cylinder 23, and wherein a second printing unit 21, in addition to a cylinder group 22 consisting of a forme or plate cylinder and a blanket or rubber cylinder, also has a second sheet-guiding impression cylinder 24. An intermediate module 25 for producing impressions using inkjet printers 26 and 27 is provided between the two printing units 20, 21.

[0057] The intermediate module 25 has a sheet guide path 28, which consists of a first and second guide region 28a, 28b extending flat in the sheet travel direction and a third guide region 28c extending curvedly. The flat first and second guide region 28a, 28b extends essentially tangentially from the circumferential surface of the first printing cylinder 23 at a transfer or takeover point Ü1 in a flat extension downwards in the direction of the second printing cylinder 24.

[0058] The third guide region 28c extends upwardly curved in the sheet travel direction R. The curved guide region 28c adjoins seamlessly the lower end of the first and second flat guide regions 28a, 28b in the sheet travel direction R and is curved essentially in a circular arc in the sheet travel direction R and tapers essentially tangentially to the circumferential surface at a transfer or takeover point Ü2 of the second printing cylinder 24 in the second printing unit 21.

[0059] The transfer / takeover points Ül, Ü2 (actually lines) are to be considered as the positions in the transport path at which the transport plane of the printing sheets D touches the respective surface of one of the printing cylinders 23, 24.

[0060] The sheet guide track 28 is designed in the form of a sheet guide plate which extends across the width of the sheet-fed printing press 1.

[0061] In the sheet guide plate of the sheet guide track 28, openings A (shown in Figure 4) for sheet guiding means are provided as openings A extending longitudinally and parallel to the sheet travel direction R.

[0062] Grippers 33, 37 (see below) extend through the openings A, which are arranged in a largely uniform distribution across the entire width of the sheet guide track 28. These grippers are arranged on gripper systems 32, 36, which are guided below the sheet guide track 28 and at least temporarily parallel to it. They serve to grasp and release the leading edge of the printed sheets D to be transported through the sheet-fed offset printing press 1 during their feeding to and subsequent removal from the sheet guide track 28.

[0063] Viewed axially relative to the printing cylinders 23, 24, in the central guide area of ​​the sheet guide track 28, second openings B extending in the sheet travel direction R are arranged (see also Figure 4). The openings B are distributed symmetrically to the center of the sheet guide track 28 across the width of the sheet guide track. Suction belt conveyors 29 are arranged in the openings B such that they enter the sheet guide area of ​​the flat first and second guide areas 28a, 28b from below. By means of the suction belt conveyors 29, the printed sheets D can be conveyed completely flatly along the sheet guide track 28. The printed sheets D are sucked with their undersides against suction belts 29A (see Figure 5) of the suction belt conveyors 29 by means of a vacuum effect, without slipping. For this purpose, at least two suction belt conveyors 29 are arranged side by side, but preferably three or four suction belt conveyors 29.The suction belt conveyors 29 each have a suction belt 29A provided with suction openings, which is guided over deflection rollers 29C (see Figure 5) and stretched over suction chambers 29B in the plane of the sheet guide track 28. Each suction belt 29A is connected to at least one controllable drive (not shown here) to generate the drive movement, which is preferably introduced into the suction belt conveyor 29 via one of the deflection rollers 29C.

[0064] A drive can be assigned to a single suction belt conveyor 29 as an individual drive or to groups of suction belt conveyors 29 together or to all suction belt conveyors 29 of an intermediate module 25 together.

[0065] Each suction belt 29A is thus guided in the conveying plane of the sheet guide track 28 over a suction chamber 29B, which sucks the printed sheets D to be transported by means of negative pressure through suction openings, firmly adhering them to a suction belt 29B which is also provided with suction openings, wherein during the sheet transport, suction openings in the suction chamber 29B and the suction belt 29A always correspond, so that the printed sheets D are always held on the suction belts 29A.

[0066] In an arrangement of more than two suction belt conveyors 29, the application of negative pressure can be controlled in width depending on the format by switching negative pressure on or off in parts within suction chambers 29B or in individual suction chambers 29B as a whole. The switching can be related to the working cycle or can also be varied in terms of pressure or volume flow.

[0067] The suction belt conveyors 29 can be driven jointly or individually by means of the aforementioned drives. In particular, with individual drives per suction belt conveyor 29, alignment of the printed sheets D can also be provided before and / or after printing by the inkjet printers 26, 27 in order to achieve a precise position during printing and sheet transfer.

[0068] To ensure synchronized and positionally correct sheet transport under the inkjet printers 26, 27, one or more sensors S for detecting the leading edges of the sheets can be arranged above the sheet guide track 28 in the area of ​​a sheet transfer from the printing cylinder 23 to the suction belt conveyors 29, so that the inkjet printers 26, 27 can be controlled precisely to a region to be printed on the incoming printed sheet D transported in the sheet travel direction R by means of the suction belt conveyors 29. Furthermore, one or more sensors S for detecting the leading edges of the printed sheets D can be arranged in the area of ​​a sheet transfer from the suction belt conveyors 29 to the printing cylinder 24. This makes it possible to detect the respective sheet position in relation to the transport movement of the entire printing press and, if necessary, to influence this by means of the suction belt conveyors 29 so that the printed sheets D to be printed can be transported on in the sheet travel direction R with the correct registration.

[0069] A first endless chain conveyor 30 is provided for conveying sheets along the printing cylinder 23 and from the printing cylinder 23 to the sheet guide track 28. A conveyor chain running around the circumference of the printing cylinder 23 is provided at each end face of the printing cylinder 23. Furthermore, a chain guide track 31 is provided for each conveyor chain, which guides the conveyor chain out of the circumference of the printing cylinder 23. The first chain conveyor 30 is provided with at least three gripper systems 32 extending across the entire width of the sheet guide track 28 and connected to the end faces of the conveyor chains, which gripper systems have a plurality of grippers 33 for grasping and releasing the leading edge of the printed sheets D to be transported. To ensure precise sheet guidance, the gripper systems 32 on the printing cylinder 23 are each guided in one of two cylinder channels 23A and 23B on a precisely positioning holder 23C and 23D.The holders 23C, 23D can have a mechanical or magnetic locking mechanism for the play-free guidance of the gripper systems 32 running therein.

[0070] The openings A in the sheet guide track 28 are distributed at the distance of the grippers 33 on the gripper systems 32 (see Fig. 4 and Fig. 6).

[0071] A second endless chain conveyor 34 is provided for conveying sheets along the printing cylinder 24 and from the sheet guide track 28 to the printing cylinder 24. A conveyor chain running around the circumference of the printing cylinder 24 is provided at each end of the printing cylinder 24. Furthermore, a chain guide track 35 is provided for each conveyor chain, which guides the conveyor chain out of the circumference of the printing cylinder 24. The second chain conveyor 34 is provided with at least three gripper systems 36 extending across the entire width of the sheet guide track 28 and connected to the conveyor chains at the end faces. The gripper systems have a plurality of grippers 37 for grasping and releasing the leading edge of the printed sheets D to be transported.

[0072] To ensure precise sheet guidance, the gripper systems 36 on the printing cylinder 24 are each guided in one of two cylinder channels 24A and 24B on a precisely positioned holder 24C and 24D. The holders 24C, 24D can have a mechanical or magnetic locking mechanism for play-free guidance of the gripper systems 36 entering there.

[0073] The openings A in the sheet guide track 28 are in turn distributed at the distance of the grippers 37 on the gripper systems 36 (see Fig. 4 and Fig. 6).

[0074] On the underside of the curved guide track 28, a cross member 38 in the form of a tube extending across the width of the machine is provided, which serves to easily dismantle the unit of the curved guide track 28.

[0075] In conjunction with the cross member 38, a vacuum device can also be provided to enable the extraction of air through the sheet guide track 28. This creates a suction effect on the printed sheet D passing along the sheet guide track 28 in order to keep it in contact with the sheet guide track 28. This allows the printed sheet D to be safely guided from the suction belt conveyors 29 to the printing cylinder 24 on the printing unit 21 after it has run off.

[0076] The traverse 38 can also be used to deform the sheet guide path 28 in order to adapt the transport path of the printed sheets D to the operating conditions during the printing process.

[0077] Figure 4 shows a top view of the sheet guide track 28. The printed sheets D are transported from right to left in the sheet travel direction R. For clarity, the sheet positions are shown in dashed lines and marked with the reference symbols D1, D2, and D3.

[0078] The first printing cylinder 23 (contour on the right in the image) extends below the sheet guide track 28. The gripper systems 32 run in the sheet travel direction R from the printing cylinder 23 into a transfer area of ​​the flat first guide area 28a on the sheet guide track 28 and parallel to it. The printed sheet D (position D1) is held at the leading edge by the grippers 33 of a gripper system 32. The grippers 33 project upward through the openings A in the sheet guide track 28 and guide the printed sheet D onto the surface of the sheet guide track 28.

[0079] The suction belt conveyors 29 extend as far as possible from the downstream side into the aforementioned transfer area of ​​the flat guide area 28a. The distance of the suction belt conveyors 29 from the transfer point Ü1 is determined by how far a deflection roller 29C on the suction belt conveyor 29 can be positioned into the distance below the sheet guide path 28 to the printing cylinder 23. In the transfer area of ​​the flat first guide area 28a, the suction belts 29A are moved over the suction chambers 29B synchronously with the printed sheets D (position D1), which are still guided by the grippers 33.

[0080] After the printed sheet D has been taken over by the suction belt conveyors 29, the grippers 33, guided by the gripper systems 32, descend into the openings A from the area of ​​the sheet guide track 28 below its surface.

[0081] From the point of transfer from the grippers 33, the suction belt conveyors 29 guide the printed sheet D in a flat extension from the first guide area 28a, designed as a transfer and feed area, in the sheet travel direction R into a flat printing area 28b that continues this area (see position D2). The printed sheets D are then guided by the suction belt conveyors 29 under the inkjet printers 26, 27 for printing, coding, or coating (position D2).

[0082] The suction belt conveyors 29 hold the printed sheet D in a flat extension under the inkjet printers 26, 27 and thus enable reliable and high-quality printing or coating.

[0083] In addition, it can be provided that the suction belt conveyors 29 are provided with diverging adjustable spacing to ensure the flatness of the printed sheet D in the sheet travel direction R. By increasing the spacing of the suction belt conveyors 29 slightly and symmetrically outwards to the format center in the sheet travel direction R, the printed sheet D is held taut transversely to the sheet travel direction R and can thus be printed precisely by the inkjet printers 26, 27.

[0084] The suction belt conveyors 29 continue to guide each printed sheet D in a flat extension from the second flat printing area 28b even after printing. The printed sheet D is transferred to a curved guide area 28c (position D3), which continues the second guide area 28b, designed as a printing area, in the sheet travel direction R. Due to the upward curvature of the curved guide area 28c compared to the flat extension, the printed sheet D lies flat against the sheet guide track 28 and is conveyed with its leading edge into the transfer area to the second endless chain conveyor 34 on the second printing cylinder 24 in the second printing unit 21.The leading edge of the printed sheet D is gripped by grippers 37 emerging from the sheet guide track 28 through the openings A in front of the leading edge of the sheet, and is fixed to a gripper system 34 (position D3) and moved with it in the sheet travel direction R, while the printed sheet D is still held at its trailing edge by the suction belt conveyors 29 and moved forward synchronously with the gripper system 34. At least the gripper systems 32 on the first endless chain conveyor 30 are provided with recesses for the secure transfer of the printed sheets D to the suction belt conveyors 29, which recesses are arranged in the area of ​​the suction belt conveyors 29 (see Figure 6).

[0085] Subsequently, the gripper system 34, with the printed sheet D secured by the grippers 37, moves onto the printing cylinder 24 and is secured there to the first holder 24C in a precisely aligned position within the first cylinder channel 24A for production purposes. Thus, the printed sheet D can also be printed in the printing unit 21 precisely and in register with the imprint in the printing unit 20 and the images, codes, or coatings applied in the intermediate module 25 by means of the inkjet printers 26, 27.

[0086] Figure 5 shows an enlarged view of the intermediate module 25 on the printing cylinders 23, 24 of the printing units 20, 21. The path of a printed sheet D is shown simultaneously in seven different positions D(l) to D(7) of the transport process from the printing cylinder 23 via the sheet guide track 28 to the printing cylinder 24. In this illustration, the reference symbols D(l) to D(7) refer to the leading edge of the printed sheet D. The length of the printed sheet D is shown in abbreviated form in each position for reasons of clarity. It goes without saying that in each position of the process shown, only individual printed sheets D are conveyed one after the other and that overlap of several printed sheets D cannot occur.

[0087] The first position D(l) of the printed sheet D is shown such that the printed sheet D is located with its front edge in the grippers 33 on the gripper system 32, while the gripper system 32 is fixed in the first holder 23 C in the cylinder channel 23 A on the printing cylinder 23 of the first printing unit 20.

[0088] The second position D(2) shows the printed sheet D at the grippers 33, wherein the gripper system 32 (by means of the first endless chain conveyor 30) has been moved further from the holder 23C on the printing cylinder 23 onto the first chain guide track 31 in a forward movement parallel to the sheet guide track 28 in the sheet travel direction R.

[0089] The third position D(3) shows the printed sheet D in the opening grippers 33, with the gripper system 32 being moved further on the first chain guide track 31 parallel to the sheet guide track 28 in the sheet travel direction R into the feed area (flat first guide area 28a). In this position, the leading edge of the printed sheet D has already reached the beginning of the suction belt conveyors 29. The area of ​​the leading edge of the printed sheet D is held under negative pressure on the suction belts of the suction belt conveyors 29, whose conveying speed is synchronized with that of the gripper system 32. The grippers 33 on the gripper system 32 can now be opened safely, since the suction belt conveyors 29 move the printed sheet D forward on the flat first guide area 28a in a correct register position required for print processing.

[0090] As a result, the gripper system 32 on the first chain guide track 31 with open grippers 33 descends under the sheet guide track 28 without damaging the leading edge of the printed sheet D.

[0091] The fourth position D(4) shows the printed sheet D, which is moved further along the suction belt conveyors 29 via the sheet guide track 28 in the sheet travel direction R. The suction belt conveyors 29 convey the printed sheet D here with precision and at an adjusted speed through the flat second guide area 28b, designed as a printing area, beneath the inkjet printers 26, 27.

[0092] The fifth position D(5) shows the printed sheet D, which is moved further by the suction belt conveyors 29 over the sheet guide track 28 in the sheet travel direction R to the curved guide area 28c. The suction belt conveyors 29 continue to convey the printed sheet D precisely and at an adjusted speed, with the printed sheet D adhering to the upwardly curved sheet guide track 28 due to the forward movement. The printed sheet D also does not need to be guided separately in the front area, which is no longer held by the suction belt conveyors 29.

[0093] Alternatively, starting from the cross member 38 under the sheet guide track 28, a suction and conveying effect can be exerted through the openings A onto the underside of the printed sheet D. At this point in time, the gripper system 36 with open grippers 37 runs from below on the chain guide track 35 of the second endless chain conveyor 34 in the direction of the sheet guide track 28.

[0094] The sixth position D(6) shows the printed sheet D, which is moved further by the suction belt conveyors 29 over the sheet guide track 28 in the sheet travel direction R on the curved guide area 28c. The suction belt conveyors 29 continue to convey the printed sheet D precisely and at an adjusted speed, adhering to the upwardly curved sheet guide track 28. Alternatively, a suction and conveying effect can be exerted through the openings A on the underside of the printed sheet D, starting from the cross member 38 under the sheet guide track 28.

[0095] At this point, the gripper system 36, with open grippers 37 coming from below on the chain guide track 35, has reached the sheet guide track 28, so that the grippers 37 protrude upwards above the sheet guide track 28. The printed sheet D is thus pushed precisely into the open grippers 37 on the gripper system 36 by the suction belt conveyors 29. In a short forward movement of the gripper system 36, the grippers 37 are then closed and hold the leading edge of the printed sheet D precisely.

[0096] The seventh position D(7) of the printed sheet D is again shown such that the printed sheet D is held with its leading edge in the grippers 37 on the gripper system 36, while the gripper system 36 is now fixed in the first holder 24C in the cylinder channel 24A on the printing cylinder 24 of the second printing unit 21. The printed sheet D can now be printed with precision in the second printing unit 21.

[0097] Thus, with reference to Figure 5, the sheet transport of a printed sheet D from the first printing cylinder 23 in printing unit 20 via the sheet guide track 28 in the intermediate module 25 using suction belt conveyors 29 to the second printing cylinder 24 in printing unit 21 with simultaneous printing by means of one or more inkjet printers 26, 27 is characterized in detail.

[0098] Figure 6 shows, in a cross section through the flat first guide region 28a or the flat second guide region 28b designed as a pressure region within the sheet guide path 28, how the suction belt conveyors 29 are arranged in the sheet guide path 28 and how a gripper system 32 is assigned to the sheet guide path 28 and the suction belt conveyors 29.

[0099] The gripper system 32 is connected at each end to an endless chain conveyor 30, each of which circulates in a closed chain guide track 31. The chain guide tracks 31 are guided around the printing cylinder 23 and, in the area of ​​the intermediate module 25, have a track guide that deviates from the contour of the printing cylinder 23.

[0100] First, in Figure 6, a coupling element 32A is also indicated on the underside of the gripper system 32, which serves for the precise and play-free coupling of the gripper system 31 to a holder 23C or 23D in a cylinder channel 23A, 23B of the printing cylinder 23. Thus, each gripper system 32 can be transported in a position that is always the same for each cylinder channel 23A, 23B during one revolution around the printing cylinder 23 and is relevant for the transport of the printed sheets D with respect to the printing to be carried out with precise registration in the printing unit 20, 21.

[0101] On the upper side, the gripper system 32 carries a series of grippers 33, which are distributed approximately evenly across the width of the gripper system 32 and each interact with a gripper cuff 33a arranged on the surface of the gripper system 32. The printed sheet D is held between the grippers 33 and the gripper cuffs 32a.

[0102] The gripper system 32 is guided in the chain guide tracks 31 such that the gripper cuffs 33a hold the printed sheet D at a height such that the printed sheet D is guided on the upper side of the sheet guide track 28. The gripper cuffs 33a and the grippers 33 protrude upward through the openings A in the sheet guide track 28 (see Figure 4).

[0103] Also shown here are three suction belt conveyors 29 in cross-section through suction belts 29A and suction chambers 29B. The suction belt conveyors 29 are each assigned to the surface of the sheet guide track 28 in an opening B (see Figure 5) such that the upper side is formed by a suction belt 29A in the plane of the surface of the sheet guide track 28. From each suction chamber 29B located below, a vacuum is exerted on the printed sheet D lying on top through openings in each of the suction belts 29A, so that the sheet can be guided precisely, distortion-free, and safely by the suction belt conveyors 29.

[0104] For reasons of clarity, no sheet guiding surface as shown in Figure 4 has been drawn in Figure 6 on the left and right directly next to the suction belt conveyors 29 in the sheet guide path 28. In Figure 6, a gripper 33 is arranged directly next to the suction belt conveyors 29 on the gripper system 32 and thus ensures the uniform feeding of the printed sheet D to all three suction belt conveyors 29. Should an arrangement according to Figure 6 prove disadvantageous due to negative pressure effects from the suction belt conveyors 29 in the side area of ​​the suction belts 29A, the arrangement of the openings B in the sheet guide path according to Figure 4 can be used without further ado.

[0105] The suction belt conveyors 29 and the conveying area of ​​the gripper system 32 must overlap over a sufficiently large area in the sheet travel direction R to ensure that the printed sheets D are reliably picked up by the suction belt conveyors 29 from the gripper system 32. Thus, the suction belt conveyors 29 extend into the movement area of ​​the gripper system 32. Therefore, three recesses 32B shaped according to the cross-section of the suction belt conveyors 29 are provided in the top side of the gripper system 32 so that the gripper system 32 passes the suction belt conveyors 29 without contact during movement in the sheet travel direction R.

[0106] A weakening of the cross-section of the gripper system 32 in the area of ​​the recesses 32B, which initially appears disadvantageous due to this arrangement, turns out to be unproblematic. Namely, when transferring the printed sheet from the printing cylinder 23 into the area of ​​the sheet guide track 28, the gripper system 32 is guided only in a planar movement, during which no transverse forces act on the gripper system 32. During the return movement of the gripper system 32 via the chain guide track 31, the gripper system 32 is guided around a curve, but this is harmless because no printed sheet D needs to be guided.In the circular guide around the printing cylinder 23, the gripper system 32 is then locked again in the channels 23A, 23B on one of the holders 23C or 23D, so that a safe and stress-free guidance of the gripper systems 32 is ensured even when taking over printed sheets D on the printing cylinder 23 from the machine area of ​​the sheet-fed offset printing press preceding the printing unit 20.

[0107] In general, the following should be noted regarding the function of the intermediate module 25 according to the invention in a sheet-fed offset printing press:

[0108] The device according to the invention is based on the fact that printed sheets D to be printed are guided in a planar extension in an intermediate module 25 arranged between two printing units 20, 21 or sheet-guiding units of a sheet-fed offset printing press in the area of ​​the inkjet printer(s) 26, 27 positioned there. A drive system is provided for sheet transport that is controllable independently of the printing press but adjustable with respect to the speed of the printing press and, if necessary, the function of the inkjet printers 26, 27.

[0109] The design of the device according to the invention is based on the fact that sheet-fed printing presses usually have printing cylinders with a diameter twice that of plate and blanket cylinders, as well as two rows of grippers evenly distributed around the circumference in cylinder channels. Due to the larger diameter, the printing material is less curved during transport. Analogously, sheet transport drums, also with a diameter twice the size and two rows of grippers, are arranged between the printing units. In the arrangement according to the invention, in a compact design, the length of the transport path of the printed sheets D over the sheet guide track 28 corresponds to the circumferential length of a single-size cylinder or half the circumferential length of a double-size sheet guide drum (see sheet guide drum 3, Fig. 1 or 2) in a conventional sheet-fed offset printing press. The intermediate module 25 replaces a sheet guide drum with a transport module with a largely flat and then curved sheet guide.The length of the sheet guide path 28 extending from the tangential transfer point Ü1 of the flat first guide area 28a on the first printing cylinder 23 to the tangential approach of the curved guide area 28c to the transfer point Ü2 on the second printing cylinder 24 corresponds to half the circumference of a double-sized sheet transport drum.

[0110] During transport, a distance then arises on the sheet guide track 28 between the trailing edge of a leading printed sheet D and the leading edge of a following printed sheet D, corresponding to the sheet spacing that arises during transport on double-sized sheet transport drums.

[0111] Depending on the design of the sheet guide path 28 in the intermediate module 25, a transport path of varying length may result between the first printing cylinder 23 in the printing unit 20 and the second printing cylinder 24 in the printing unit 21. The length of the transport path in the intermediate module 25 may also differ from the transport path via sheet transport drums (see 3, 14 according to Figures 1 and 2) in conventional sheet transport units in sheet-fed offset printing presses.

[0112] In an intermediate module 25 according to the invention, the flat sheet guide track 28 makes it possible to guide the printed sheets D over a smaller or larger distance between the printing units 20, 21. Thus, the length of the sheet guide track 28 can be adapted to the length of the transport path of the printed sheets D, corresponding to a path around one or more sheet transport drums between the printing cylinders 23, 24 of the printing units 20, 21, or it can deviate from this length.

[0113] Advantageously, in connection with this, in the device according to the invention, the transport speed of the printed sheets D in the intermediate module 25 arranged between two printing units 20, 21 for carrying out the inkjet printing can be varied relative to the speed of the printing units 20, 21.

[0114] The transport of the printed sheets D can thus be carried out at a variable speed. In the case of a sheet guide track 28 that is longer than the path via sheet-guiding cylinders, the transport speed in the intermediate module 25 can be accelerated when feeding the printed sheet D onto the sheet guide track 28 after it has been taken over by the suction belt conveyors 29 and released by the preceding printing unit 20. The acceleration can also be achieved in such a way that the printed sheet D can be printed with good quality by the inkjet printers 26, 27 at an advantageously adjusted speed on its way over the flat second guide area (printing area) 28b.

[0115] After printing, each printed sheet D in the intermediate module 25 is accelerated to a value above the machine speed by means of the inkjet printers 26, 27 and then brought back to the machine speed of the printing units 20, 21, so that it reaches the machine speed of the printing units 20, 21 again via the curved guide area 28c of the sheet guide path 28 and can be accurately picked up by the gripper systems 36 on the second printing cylinder 24.

[0116] Similarly, in the case of a sheet guide path 28 that is shortened compared to the path via sheet-guiding cylinders, the transport speed in the intermediate module 25 can be reduced when feeding the printed sheet D onto the sheet guide path 28 after being taken over by the suction belt conveyors 29. The reduction is achieved in such a way that the printed sheet D is printed at an advantageously reduced speed on its path over the flat second guide area (printing area) 28b by means of the inkjet printers 26, 27.

[0117] Similarly, if required, each printed sheet D in the intermediate module 25 can be accelerated again to the speed of the printing units 20, 21 after printing by means of the inkjet printers 26, 27, so that it reaches the machine speed of the printing units 20, 21 via the curved guide area 28c of the sheet guide path 28 and can be accurately picked up by gripper systems 36 on the second printing cylinder 24.

[0118] List of reference symbols

[0119] 1 sheet-fed printing press

[0120] 2 display system

[0121] 3 sheet guide drum

[0122] 4 grippers

[0123] 5 housings

[0124] 6 suction heads

[0125] 7 Inkjet printers 8 T inten strahl printers

[0126] 9 guided tours

[0127] 10 rolls

[0128] 11 Device, electrostatic charging of the sheet guide drum

[0129] 12 Device for electrostatic charging on the delivery system

[0130] 13 printing cylinders

[0131] 14 Intermediate drum

[0132] 15 printing unit

[0133] 16 printing units

[0134] 17 printing unit

[0135] 18 Intermediate module

[0136] 19 Intermediate module

[0137] 20 printing units

[0138] 21 printing unit

[0139] 22 Cylinder group (form / plate cylinder, blanket / rubber cylinder)

[0140] 23 printing cylinders

[0141] 24 printing cylinders

[0142] 25 intermediate module

[0143] 26 T inkjet printer

[0144] 27 inkjet printers

[0145] 28 curved guideway

[0146] 29 suction belt conveyors

[0147] 30 first endless chain conveyor

[0148] 31 first chain guide track

[0149] 32 gripper system

[0150] 33 grippers

[0151] 34 second endless chain conveyor

[0152] 35 second chain guide track

[0153] 36 gripper system

[0154] 37 grippers

[0155] 38 Traverse curved guideway

[0156] A Openings in the curved guideway for grippers to pass through

[0157] B Openings in curved guideway for access of suction belt conveyors

[0158] D Printing sheet Dl, D2, D3 Printing sheet position / Position

[0159] R Sheet travel direction

[0160] S sensor, leading edge sensor

[0161] Ü1, Ü2 handover point, takeover point

[0162] 23 A first cylinder channel

[0163] 23B second cylinder channel

[0164] 23 C first bracket

[0165] 23D second bracket

[0166] 24A first cylinder channel

[0167] 24B second cylinder channel

[0168] 24C first bracket

[0169] 24D second bracket

[0170] 28a flat first guide area / transfer / feed area

[0171] 28b flat second guide area / pressure area

[0172] 28c curved guide area

[0173] 29A suction belt

[0174] 29B Suction chamber

[0175] 29C pulley

[0176] 32A coupling element

[0177] 32B recess

[0178] 33a Gripper impacts

Claims

Patent claims 1. A method for imprinting code, text, or images by means of inkjet printers (26, 27) into printed sheets (D) printed in one or more colors by means of a sheet-fed offset printing press, wherein the printed sheets (D) are guided past one or more inkjet printers (26, 27) arranged in the sheet-guiding unit by means of a sheet-guiding unit immediately after processing or treatment in a printing unit (20) or processing unit and are fed to a further printing unit (21) or processing unit, characterized in that the printed sheets (D) are transferred in the sheet travel direction (R) from the first printing unit (20) from a gripper closure in grippers (33) in conjunction with a printing cylinder (23) directly or indirectly to a sheet guide track (28) provided with a substantially flat guide surface in the sheet-guiding unit,that the printed sheets (D) are taken over from the gripper closure by one or more conveyor devices (29) without gripper closure, that the printed sheets (D) are guided by the conveyor devices (29) without gripper closure and firmly abutting over a flat guide area (28b) of the sheet guide track (28) and in the process past the inkjet printer(s) (26, 27), that the printed sheets (D) are fed from the one or more conveyor devices (29) without gripper closure directly or indirectly to a device with gripper closure assigned to the second printing unit (21) or processing unit, and that the printed sheets (D) are transported further by the second printing unit (21) or processing unit in the gripper closure and are conveyed away from the conveyor device (29) and the sheet guide track (28).

2. Method according to claim 1, characterized in that the printed sheets (D) are aligned in the sheet guiding unit by means of the conveyor devices (29) for gripperless transport in the sheet travel direction (R) and / or transversely thereto with respect to their leading and / or a side edge and / or are taut in the transport plane.

3. Method according to claim 1 or 2, characterized in that each printed sheet (D) in the sheet guiding unit is braked by means of the conveyor devices (29) for gripperless transport in the sheet travel direction (R) before printing with the inkjet printer(s) (26, 27) by means of the conveyor devices (29) for gripperless transport and is accelerated again by the conveyor devices (29) after printing with the inkjet printer(s) (26, 27).

4. Sheet-fed offset printing press (1) for carrying out the method according to claim 1, with a sheet feeder, with the sheet feeder downstream of several printing units (20, 21) and / or processing units with sheet-guiding printing cylinders (23, 24), with sheet guiding units arranged between the printing cylinders (23, 24) of the printing units (20, 21) and / or processing units, wherein one or more inkjet printers (26, 27) are arranged in the region of one or more of the sheet guiding units, and with a sheet delivery arranged downstream of the printing units (20, 21) and processing units, characterized in that the sheet guiding unit is designed as an intermediate module (25), in that a sheet guiding track (28) extending essentially flat in the sheet travel direction (R) is arranged in the intermediate module (25),that the sheet guide path (28) is assigned means for gripperless transport of the printed sheets (D) over the sheet guide path (28) and that the inkjet printer(s) (26, 27) are arranged substantially perpendicularly relative to a flat guide region (28b) of the sheet guide path (28).

5. Sheet-fed offset printing press (1) according to claim 4, characterized in that each of the printing cylinders (23, 24) of the printing units (20, 21) or processing units adjacent to the intermediate module (25) is assigned an endless chain conveyor (30, 34) guided in two chain guide tracks (31, 35), and in that each chain conveyor (30, 34) is equipped with three or more gripper carriages (32, 36) for transporting printed sheets (D) by means of grippers (33, 37), and in that each chain conveyor (30, 34) is arranged in a region in which the printed sheets (D) are moved on gripper systems (32, 36) and are guided parallel to the sheet guide track (28).

6. Sheet-fed offset printing machine (1) according to one or more of claims 4 or 5, characterized in that the sheet guide path (28) consists of a first flat guide region (28a), a second flat guide region (28b) and a third curved guide region (28c), wherein the first flat guide region (28a) extends tangentially from a transfer point (Ül) on the first printing cylinder (23) of the first printing unit (20) or processing unit to the second flat guide region (28b), which forms a printing region in connection with the inkjet printers (26, 27), and that the third curved guide region (28c) adjoins the second flat guide region (28b) seamlessly, that the guide region (28c) is designed to curve upwards in the sheet travel direction (R) and thereby extends tangentially to the surface of the second printing cylinder (24) in the second printing unit (21) or processing unit in approaching a transfer point (Ü2).

7. Sheet-fed offset printing machine (1) according to one or more of claims 4 to 6, characterized in that the first endless chain conveyor (30) in the first flat guide area (28a) is arranged to move away tangentially from the first printing cylinder (23) and is guided parallel to the sheet guide path (28) and the second endless chain conveyor (34) in the third curved guide area (28c) is arranged to approach tangentially to the second printing cylinder (24) and is guided parallel to the sheet guide path (28).

8. Sheet-fed offset printing machine (1) according to one or more of claims 4 to 7, characterized in that the sheet guide track (28) is provided with openings (A) for the passage of grippers (33, 37) on the gripper systems (32, 36), and in that the first endless chain conveyor (30) in the first flat guide region (28a) in the region guided parallel to the sheet guide track (28) is arranged such that the grippers (33) are guided through the openings (A), and in that the second endless chain conveyor (34) in the third curved guide region (28c) in the region guided parallel to the sheet guide track (28) is arranged such that the grippers (37) are guided through the openings (A).

9. Sheet-fed offset printing press (1) according to one or more of claims 4 to 8, characterized in that in the intermediate module (25) parallel to the sheet guide track (28) and oriented in the sheet travel direction (R) two or more suction belt conveyors (29) are arranged symmetrically to the width orientation of the sheet guide track (28), wherein the suction belt conveyors (29) are arranged in openings (B) in the sheet guide track (28) in such a way that suction belts (29A) which can be subjected to negative pressure via suction chambers (29B) contact the underside of printed sheets (D) lying on the sheet guide track (28), and that the suction belt conveyors (29) extend in the sheet travel direction (R) at least from the center of the first flat guide area (28a) in the area of the parallel guidance of the endless chain conveyor (30) on the underside of the sheet guide track (28) to beyond the second flat guide area (28b).

10. Sheet-fed offset printing machine (1) according to one or more of claims 4 to 9, characterized in that the two or more suction belt conveyors (29) arranged in an intermediate module (25) parallel to the sheet guide path (28) are provided with at least one drive for generating a conveying movement via the suction belts (29A), wherein the Drives of the suction belt conveyors (29) are coupled individually, in groups or jointly to all suction belt conveyors (29) and that the suction belt conveyors (29) are designed to be controllable individually, in groups or all jointly with regard to their conveying movement with regard to the sheet transport through the sheet-fed offset printing press.

11. Sheet-fed offset printing press (1) according to one or more of claims 4 to 10, characterized in that the two or more suction belt conveyors (29) arranged in an intermediate module (25) parallel to the sheet guide path (28) are provided with a control for a suction air supply for generating a negative pressure in the suction chambers (29B) for the suction belts (29A), wherein the negative pressure supply of the suction belt conveyors (29) is designed to be individually or jointly controllable for the suction belt conveyors (29) with regard to the sheet transport through the sheet-fed offset printing press, and wherein the negative pressure supply within each of the suction belt conveyors (29) is designed to be zonally controllable in the sheet travel direction (R).

12. Sheet-fed offset printing machine (1) according to one or more of claims 4 to 9, characterized in that the intermediate module (25) with the inkjet printers (26, 27) is arranged between two printing units (20, 21), between a printing unit and a processing unit, between two processing units, between a last printing unit and a sheet delivery unit, or between a processing unit and a sheet delivery unit.

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