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 lower suction belt conveyors (29) and upper transfer conveyors (30) 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 substrates 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 often cannot be reliably maintained. Thin print substrates tend to slide together on the cylinder, while thicker print substrates 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] 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.

[0011] The solution to the problem is carried out with the features of claim 1. Advantageous further developments emerge from the subclaims.

[0012] A method is provided for imprinting code, text, or images using inkjet printers into sheets printed in one or more colors using a sheet-fed offset printing press. Immediately following 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 another printing unit or processing unit.

[0013] 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 guide 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-closed position and removed by the conveyor and sheet guide track. Advantageously, the printed sheets are aligned in the sheet guide unit by means of the conveyors for gripperless transport in the sheet travel direction and / or transversely thereto with respect to their leading and / or one side edge and / or taut in the transport plane.

[0017] 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).

[0018] 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.

[0019] 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.

[0020] Advantageously, several transfer conveyors arranged symmetrically across the width of the sheet guide path are assigned to the first printing cylinder in the first printing unit or processing unit adjacent to the intermediate module. Each transfer conveyor is designed as a suction belt conveyor with a suction belt circulating above a suction chamber. They serve to transport printed sheets from the grippers of the printing cylinder without the use of grippers. Each transfer conveyor is arranged parallel to the sheet guide path in a section that moves the printed sheets.

[0021] 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.

[0022] Advantageously, the transfer conveyors are arranged above the printing cylinder and the sheet guide track in the first flat guide area, extending tangentially away from the first printing cylinder and parallel to the sheet guide track. The transfer conveyors are positioned so that the suction belts on the underside of the transfer conveyors contact the top surface of the printed sheets on the printing cylinder and on the sheet guide track.

[0023] Advantageously, the sheet guide track is provided with openings at its inlet and outlet ends in the sheet travel direction for the passage of grippers on the printing cylinders. The first printing cylinder is arranged on the first flat guide area such that the grippers are guided through the openings, and the second printing cylinder is arranged on the third curved guide area such that the grippers are guided through the openings.

[0024] Advantageously, two or more suction belt conveyors are arranged in the intermediate module, parallel to the sheet guide track and oriented in the sheet travel direction, symmetrically to the width of the sheet guide track. These are arranged in openings in the sheet guide track such that suction belts, which can be subjected to negative pressure via suction chambers, contact the underside of printed sheets resting on the sheet guide track. The suction belt conveyors extend below the sheet guide track 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 transfer conveyors on the top side 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 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, it is therefore provided to implement a modular sheet transport in a sheet-fed offset printing press in such a way that a digital printing device with inkjet printers can be adapted instead of a sheet transport drum.

[0033] The modular design of the sheet-fed offset press, with identical and variably connectable units, remains intact. 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.

[0034] 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.

[0035] 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 intakes. The substrate is transported via suction belts, starting from the first printing cylinder in front of the intermediate module with the inkjet printers, to the printing cylinder or sheet transport drum that follows the intermediate module with the inkjet printers. Therefore, this device does not provide for sheet transport in the gripper closure in conjunction with the intermediate module. This eliminates the need to consider specifications for sheet transfer and gripper opening devices.

[0036] Suction belt devices can be used to tighten the printed sheets, which is advantageous for printing with inkjet printers. For the printed side of the sheet, this can be done using stations outside the printing area or generally on the reverse side of the sheet for the entire sheet area.

[0037] 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.

[0038] 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.

[0039] In addition, an air-operated sheet guide table can be used for stable and smear-free sheet guidance.

[0040] Further details are explained in more detail using an embodiment shown in the drawing.

[0041] Here,

[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 is a section through a device according to the invention with a view of a feeding printing unit. 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 and can be adjusted in the circumferential direction relative to the grippers 4 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Figure 2 shows an alternative design known in the prior art, according to which the assembly consisting of the sheet guide drum 3 and the inkjet printer 7, 8 is arranged between the 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. 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.

[0053] 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 unit.

[0054] 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).

[0055] 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.

[0056] The intermediate module 25 has a curved guide track 28, which consists of a flat extending first and second guide area 28a / 28b and a third guide area 28c, which may extend in a slightly curved manner.

[0057] The flat first and second guide areas 28a / 28b extend essentially tangentially from the circumferential surface of the first printing cylinder 23 at a transfer or takeover point Ü1 in a flat extension and essentially horizontally or only slightly sloping 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 end of the first and second guide regions 28a / 28b located in the sheet travel direction R, is curved approximately in the shape of a circular arc in the sheet travel direction R, and finally runs tangentially to the circumferential surface of the second printing cylinder 24 at a transfer or takeover point Ü2 in the second printing unit 21. The transfer / takeover points Ül, Ü2 (actually lines) are to be considered the positions in the transport path at which the transport plane of the printed sheets D touches the respective surface of one of the printing cylinders 23, 24.

[0059] The sheet guide track 28 is designed as a sheet guide plate that extends across the width of the sheet-fed printing press 1. In the end region of the sheet guide plate of the sheet guide track 28 facing the printing cylinders 23, 24, openings A (shown in Figure 4) are provided for gripper passages, extending parallel to the sheet travel direction R and formed as rectangular incisions in the ends of the sheet guide plate.

[0060] Grippers 33, 37 (see below) extend through the openings A, which are arranged in a largely even distribution across the entire width of the sheet guide track 28. The grippers 33, 37 are arranged as two rows of grippers on each of the printing cylinders 23, 24 and serve to grip and release the leading edge of the printed sheets D to be transported through the sheet-fed offset printing press 1. In this case, the printed sheets D are released by the grippers 33 on the printing cylinder 23 as they are fed to the sheet guide track 28 and then, as they are taken over from the sheet guide track 28, are gripped again at their leading edge by the grippers 37 on the printing cylinder 24. During the rotation of the printing cylinders 23, 24, the grippers 33, 37 mesh with the leading and trailing edges of the sheet guide track 28 in the area of ​​the openings A.

[0061] Viewed axially relative to the printing cylinders 23, 24, second openings B extending in the sheet travel direction R are arranged in the central guide region of the sheet guide track 28 (see also Figure 4). The openings B are distributed symmetrically to the center across the width of the sheet guide track 28. Suction belt conveyors 29 are arranged in the openings B such that they enter the sheet guide region of the flat first and second guide regions 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 slip-free against suction belts 29A (see Figure 5) of the suction belt conveyors 29 by means of a vacuum effect.

[0062] For this purpose, at least two suction belt conveyors 29 are arranged next to one another, 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 via 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.

[0063] 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 of an intermediate module 25 together.

[0064] 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.

[0065] Viewed in the axial direction to the first printing cylinder 23, in the central guide area of ​​the sheet guide track 28, several transfer conveyors 30 designed as suction belt units are arranged from above from a sheet guide area in front of the transfer point Ü1 from the printing cylinder 23 to the flat first guide area 28a (see also Figure 4).

[0066] The transfer conveyors 30 are arranged opposite the suction belt conveyors 29 and cover their conveying area in the sheet travel direction R over a predefined or adjustable distance.

[0067] The transfer conveyors 30 ensure the smooth transfer of sheets from the first printing cylinder 23 in the printing unit 20 to the sheet guide track 28. By means of the transfer conveyors 30, the printed sheets D are removed safely and accurately from the grippers 33 of the printing cylinder 23 and transferred to the sheet guide track 28 until they are transferred by the suction belt conveyors 29. The printed sheets D are sucked onto the suction belts 30A (see Figure 5) of the transfer conveyors 30 on their upper side by means of a vacuum effect, without slipping.

[0068] For this purpose, at least two transfer conveyors 30 are arranged next to one another, but preferably three, four or more transfer conveyors 30. The transfer conveyors 30 each have a suction belt 30A provided with suction openings, which is guided over deflection rollers 30C (see Figure 5) and stretched over suction chambers 30B in a plane parallel to the sheet guide track 28. The suction belts 30A are guided in such a way that they securely contact a printed sheet D on the sheet guide track 28 on its upper side, but do not press it against the sheet guide track 28. Each suction belt 30A is therefore guided just above the conveying plane of the sheet guide track 28 over a suction chamber 30B, which sucks the printed sheets D to be transported upwards through suction openings by means of negative pressure, firmly adhering them to a suction belt 30B that is also provided with suction openings.During sheet transport, suction openings in suction chamber 3 OB and suction belt 30A must constantly correspond so that the printed sheets D are always held on the suction belts 30A.

[0069] Similar measures are possible for the two types of conveyor systems, namely suction belt conveyors 29 and transfer conveyors 30.

[0070] In an arrangement of more than two suction belt conveyors 29 or transfer conveyors 30, the application of negative pressure can be controlled in length and width depending on the format by switching off or on the negative pressure in parts within suction chambers 29B or 30B or in individual suction chambers 29B or 30B as a whole. Such switching can be related to the operating cycle of the sheet-fed offset printing press and / or can also be varied in terms of pressure or volume flow.

[0071] Each suction belt 29A, 30A is connected to at least one controllable drive (not shown here) to generate the drive movement in the sheet conveying direction R. The drive movement is preferably introduced into the suction belt conveyor 29 or transfer conveyor 30 via one of the several provided deflection rollers 29C, 30C.

[0072] The drives can be assigned to each individual suction belt conveyor 29 or transfer conveyor 30 as an individual drive or they can be assigned to groups of suction belt conveyors 29 or transfer conveyors 30 together or to all suction belt conveyors 29 or transfer conveyors 30 of an intermediate module 25 together.

[0073] The suction belt conveyors 29 or transfer conveyors 30 can be driven jointly or individually using the aforementioned drives. In particular, with individual drives per suction belt conveyor 29 or transfer conveyor 30, 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 precise sheet position and alignment during printing and sheet transfer.

[0074] In order to ensure that the sheets are transported in the correct cycle and position 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 transfer conveyors 30 or suction belt conveyors 29, so that the inkjet printers 26, 27 can be controlled precisely to an area to be printed on the incoming printed sheet D that is transported in the sheet travel direction R by means of the transfer conveyors 30 or 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. In this way, the respective sheet position can be detected in relation to the transport movement of the entire printing press and, if necessary, adjusted by means of the transfer conveyors 30 orSuction belt conveyor 29 can be influenced in such a way that the sheets D to be printed can be transported further in the sheet travel direction R in a proper manner.

[0075] On the underside of the sheet guide track 28, a cross member 38 extending across the width of the machine can be provided, which serves to easily dismantle the unit of the sheet guide track 28.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] The first printing cylinder 23 (contour on the right in the image) extends below the sheet guide track 28. The printing cylinder has grippers 33 in cylinder channels 23A, 23B, which run into openings A in a transfer area of ​​the flat first guide area 28a on the sheet guide track 28. The printed sheet D (position D1) is held by the grippers 33 of the printing cylinder 23 at the front edge, with the grippers 33 projecting upwards through the openings A in the sheet guide track 28 and guiding the printed sheet D onto the surface of the sheet guide track 28. Furthermore, Figure 4 shows that four transfer conveyors 30 are assigned to the upper side of the sheet guide track 28 opposite in the sheet travel direction R in the aforementioned transfer area of ​​the flat guide area 28a and surrounding the zone of the transfer point Ü1.The transfer conveyors 30 cover the zone in which the grippers 33 intersect the beginning of the sheet guide track 28 and extend in the sheet travel direction R into the conveying area of ​​the suction belt conveyors 29.

[0080] The distance of the suction belt conveyors 29 from the transfer point Ü1 is determined by how far a deflection roller 29C can be positioned in the distance below the sheet guide track 28 to the printing cylinder 23.

[0081] In the transfer area up to and on the flat first guide area 28a, the suction belts 30A of the transfer conveyors 30 are moved over the suction chambers 30B synchronously with the printed sheets D (position Dl) which are still guided here by the grippers 33.

[0082] In this area on the printing cylinder 23, the grippers 33 are moved from a closed position to an open position. The transfer conveyors 30 take over the conveyance of the printed sheet D from the grippers 33 in their front area. After transferring the printed sheet D from the transfer conveyors 30 on the printing cylinder 23, the grippers 33 are guided downwards and submerged in the openings A from the area of ​​the sheet guide track 28 below its surface.

[0083] From the point of transfer from the grippers 33, the transfer conveyors 30 guide the printed sheet D until the leading edge of the sheet reaches the suction belt conveyors 29. The suction belt conveyors 29 then guide the printed sheet D along its underside in a flat extension from the flat first guide area 28a, designed as a transfer and feed area, in the sheet travel direction R into a flat second guide area 28b, which continues this area and is designed as a printing area (see position D2). In this process, the printed sheet D is also held on its upper side by the transfer conveyors 30 for as long as possible and can thus advantageously be guided into the printing area in a taut manner in the sheet travel direction R.

[0084] The printing sheets D are now guided by the suction belt conveyors 29 under the inkjet printers 26, 27 for printing, coding or coating (also position D2).

[0085] 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.

[0086] In addition, it can be provided that the suction belt conveyors 29 are provided with diverging adjustable settings to ensure the flatness of the printed sheet D in the sheet travel direction R. By increasing the distance of the suction belt conveyors 29 slightly and symmetrically to the format center in the sheet travel direction R outwards, the printed sheet D is also held taut transversely to the sheet travel direction R and can thus be printed precisely by the inkjet printers 26, 27.

[0087] The suction belt conveyors 29 guide each printed sheet D further in a flat extension from the flat second guide area (printing area) 28b, designed as the printing area, even after printing. The printed sheet D is transferred along the sheet guide path 28 towards the end of the latter into a slightly curved printing area 28c (position D3) which continues the flat second guide area (printing area) 28b in the sheet travel direction R. Due to the upward curvature of the guide area 28c compared to the flat extension, the printed sheet D lies flat against the sheet guide path 28. The printed sheet D is still held by the suction belt conveyors 29 on its underside and is conveyed with its leading edge into the transfer area to the grippers 37 on the printing cylinder 24 in the second printing unit 21.The leading edge of the printed sheet D is grasped by grippers 37 emerging from the sheet guide track 28 through the end openings A in front of the leading edge of the sheet and secured to the printing cylinder 23 (position D3). The printing cylinder 23 guides it further 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 cylinder movement.

[0088] The grippers 37 in the cylinder channel 24A fix the printed sheet D on the printing cylinder 24 in a precisely aligned position for production purposes. This allows the printed sheet D to be printed in the printing unit 21 with precise and accurate registration with the imprint in the printing unit 20 and the images, codes, or coatings applied in the intermediate module 25 using the inkjet printers 26, 27.

[0089] 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.The first position D(l) of the printed sheet D is shown such that the printed sheet D is located with its leading edge in the grippers 33 on the printing cylinder 23, while the grippers 33 in the cylinder channel 23A on the printing cylinder 23 of the first printing unit 20 are located at the transfer point Ü1. Thus, the leading edge of the printed sheet D is already in contact with the suction belts 30A of the transfer conveyors 30 and can be grasped early by means of negative pressure from the suction chambers 30B of the transfer conveyors 30.

[0090] The second position D(2) shows the printed sheet D where it has already left the area of ​​the grippers 33 on the printing cylinder 23 (see the dashed line representation of the gripper and cylinder channel). Here, the printed sheet D has been moved further by means of the transfer conveyors 30 in a parallel forward motion along the sheet guide track 28 in the sheet travel direction R until it reaches the beginning of the suction belt conveyors 29, which extend from below into the conveying area 28b.

[0091] The third position D(3) shows the printed sheet D as it runs off the top side of the transfer conveyors 30. The leading edge of the printed sheet is moved further 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 now held under negative pressure on the suction belts 29A of the suction belt conveyors 29, whose conveying speed is synchronized with the suction belts 30A of the transfer conveyors 30. The suction belt conveyors 29 hold the printed sheet D in a correct register position required for print processing and move it forward in a correct position on the flat first guide area 28a.

[0092] 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 precisely and at an adjusted speed through the flat second guide area (printing area) 28b under the inkjet printers 26, 27.

[0093] The fifth position D(5) shows the printed sheet D, which has been moved further by the suction belt conveyors 29 along the sheet guide track 28 in the sheet travel direction R and is now moving toward the curved guide area 28c. The suction belt conveyors 29 continue to convey the printed sheet D precisely and at an adjusted speed, since it is still partially located in the printing area and is being printed there. Alternatively, a suction and conveying effect can be exerted on the underside of the printed sheet D through the openings on the sheet guide track 28.

[0094] The sixth position D(6) shows the printed sheet D, which is advanced by the suction belt conveyors 29 over the sheet guide track 28 in the sheet travel direction R on the curved guide area 28c, whereby the printed sheet D, due to the forward movement, adheres to the upwardly curved sheet guide track 28. The printed sheet D does not need to be guided separately in the front area, which is no longer held by the suction belt conveyors 29. 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.

[0095] Alternatively, a suction and conveying effect can be exerted on the underside of the printed sheet D through openings or on the top side of the printed sheet D by means of a device below or above the sheet guide path 28.

[0096] From position D(6), the printed sheet D is pushed precisely by the suction belt conveyors 29 into the grippers 37 on the printing cylinder 24, which are open and run into the openings A at the end of the sheet guide track 28. As the printing cylinder 24 moves forward, the grippers 37 are closed and the leading edge of the printed sheet D is held precisely. The seventh position D(7) of the printed sheet D is therefore shown such that the printed sheet D is fixed with its leading edge in the grippers 37 in the cylinder channel 24A on the printing cylinder 24 of the second printing unit 21. The printed sheet D can now be printed precisely 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 transfer conveyors 30 and 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 along line ZZ in Figure 5 through the flat first guide area 28a within the sheet guide path 28, how the transfer conveyors 30 and the suction belt conveyors 29 are assigned to the sheet guide path 28. The illustration shows one of several possible embodiments.

[0099] Here, only a section of the printing cylinder 23 is shown as a rectangular elevation, so that at its upper edge, the grippers 33 are shown as a gripper row in one of the cylinder channels 23A, 23B. Thus, at the starting point of the intermediate module 25, a partial contour of the printing cylinder 23 with the transfer point Ü1 is shown.

[0100] On the upper side, the printing cylinder 23 carries a series of grippers 33, which are distributed approximately evenly across the width of the printing cylinder 23 on a gripper shaft in the cylinder channel 23A and each interacts with a gripper stop 33a arranged on the surface of the printing cylinder 23. The printed sheet D is held between the grippers 33 and the gripper stops 32a.

[0101] The grippers 33 are guided on the printing cylinder 23 such that the gripper stops 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 stops 33a and the grippers 33 protrude upward through the feed-side openings A in the sheet guide track 28 (see Figure 4).

[0102] Furthermore, two of the three suction belt conveyors 29 are shown here in cross-section through suction belts 29A and suction chambers 29B. The illustration is to be understood as a view against the sheet travel direction R according to Figure 5. 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.

[0103] For reasons of clarity, the illustration in Figure 6 is shown with a section along the line XX in Figure 4. Therefore, in the left-hand area, a suction belt conveyor 29 is shown only as a dashed frame.

[0104] Four transfer conveyors 30 are shown arranged opposite the sheet guide track 28 on its upper side. The arrangement is designed to alternate with the suction belt conveyors 29. The transfer conveyors 30 and suction belt conveyors 29 can also be arranged directly or alternatively opposite each other on the sheet guide track 28.

[0105] The conveying areas of the suction belt conveyors 29 and the transfer conveyors 30 must overlap over a sufficiently large area in the sheet travel direction R to ensure reliable transfer of the printed sheets D by the suction belt conveyors 29 from the transfer conveyors 30. Thus, the suction belt conveyors 29 extend into the movement area of ​​the transfer conveyors 30, counter to the sheet travel direction. To advantageously design the sheet transport process, the suction belt conveyors 29 and the transfer conveyors 30 can be designed in the suction chambers 29B, 30B so as to be coordinated with one another and can be variably supplied with vacuum over the length in the sheet travel direction R.

[0106] Thus, the negative pressure in the suction chambers 3 OB of the transfer conveyors 30 contacting the printed sheets from above can be switched off in a respective definable area on the discharge side when the printed sheet D has been taken over in sufficient length by the suction belt conveyors 29 contacting them from below.

[0107] Alternatively, the negative pressure in the suction chambers 30 of the transfer conveyor 30 contacting the printed sheets from above can be switched on in such a way that the printed sheets D are to be tightened during conveyance by means of the suction belt conveyor 29 over the second flat conveying area 28b (printing area).

[0108] Likewise, the negative pressure in one or more suction chambers 29B of the suction belt conveyors 29 contacting the printed sheet D from below can be switched off in a respectively definable length range on the outgoing side when the printed sheet D has been safely taken over by the grippers 37 on the second printing cylinder 24 and the printing process on the inkjet printer(s) 26, 27 has been completed.

[0109] Furthermore, the negative pressure in the suction chambers 29B of the suction belt conveyors 29 contacting the printed sheets from below can be switched off in a respectively definable feed-side area when the printed sheet D has been taken over by the transfer conveyors 30 from the grippers 33 on the first printing cylinder 23 and has not yet reached the discharge end of the transfer conveyors 30. Alternatively, or subsequently, the negative pressure in the suction belt conveyors 29 can be switched on when the leading edge of the printed sheet D runs off the transfer conveyor 30.

[0110] 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:

[0111] 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. 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.Similarly, between the printing units there are sheet transport drums with a double diameter and two rows of grippers.

[0112] In the arrangement according to the invention, the length of the transport path of the printed sheets D over the sheet guide track 28 corresponds, in a compact design, 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 and 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 track 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-size sheet transport drum.

[0113] 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.

[0114] 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.

[0115] In an intermediate module 25 according to the invention, the flat sheet guide path 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 path 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. Advantageously, in conjunction 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 performing inkjet printing can be varied relative to the speed of the printing units 20, 21.

[0116] The transport of the printed sheets D can therefore be carried out at a variable speed.

[0117] In the case of a sheet guide path 28 that is longer than the path over sheet-guiding cylinders, the transport speed in the intermediate module 25 can be accelerated when feeding the printed sheet D onto the sheet guide path 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 means of the inkjet printers 26, 27 at an advantageously adjusted speed on its way over the flat second guide area (printing area) 28b.

[0118] After printing, each printed sheet D in the intermediate module 25 is accelerated by means of the inkjet printers 26, 27 to a value above the machine speed 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 grippers 37 on the second printing cylinder 24.

[0119] 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.

[0120] 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 grippers 37 on the second printing cylinder 24.

[0121] Reference symbol list

[0122] 1 Sheet-fed printing press 2 Delivery system

[0123] 3 sheet guide drum

[0124] 4 grippers

[0125] 5 housings

[0126] 6 suction heads

[0127] 7 inkjet printers

[0128] 8 inkjet printers

[0129] 9 guided tours

[0130] 10 rolls

[0131] 11 Device for electrostatic charging of the sheet guide drum

[0132] 12 Device for electrostatic charging on the delivery system

[0133] 13 printing cylinders

[0134] 14 Intermediate drum

[0135] 15 printing unit

[0136] 16 printing units

[0137] 17 printing unit

[0138] 18 Intermediate module

[0139] 19 Intermediate module

[0140] 20 printing units

[0141] 21 printing unit

[0142] 22 Cylinder group (form / plate cylinder, blanket / rubber cylinder)

[0143] 23 printing cylinders

[0144] 24 printing cylinders

[0145] 25 intermediate module

[0146] 26 inkjet printers

[0147] 27 inkjet printers

[0148] 28 curved guideway

[0149] 29 suction belt conveyors

[0150] 30 takeover promoters

[0151] 31

[0152] 32 gripper system

[0153] 33 grippers

[0154] 34

[0155] 35

[0156] 36 grippers

[0157] A Openings in the curved guideway for grippers to pass through

[0158] B Openings in curved guideway for access of suction belt conveyors

[0159] D printing sheet

[0160] Dl, D2, D3 sheet position / position

[0161] R Sheet travel direction

[0162] S sensor, leading edge sensor

[0163] Ü1, Ü2 handover point, takeover point

[0164] 23 A first cylinder channel

[0165] 23B second cylinder channel

[0166] 24A first cylinder channel

[0167] 24B second cylinder channel

[0168] 28a flat first guide area / transfer / feed area

[0169] 28b flat second guide area / pressure area

[0170] 28c curved guide area

[0171] 29A suction belt

[0172] 29B Suction chamber

[0173] 29C pulley

[0174] 30A suction belt

[0175] 3 OB suction chamber

[0176] 30C pulley

[0177] 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, comprising a sheet feeder, a plurality of printing units (20, 21) and / or processing units with sheet-guiding printing cylinders (23, 24) arranged downstream of the sheet feeder, 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 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 machine (1) according to claim 4, characterized in that the first printing cylinder (23) in the first printing unit (20) or processing unit adjacent to the intermediate module (25) is assigned a plurality of transfer conveyors (30) arranged symmetrically distributed over the width of the sheet guide path (28), and in that each transfer conveyor (30) is equipped as a suction belt conveyor device with a suction belt (30A) circulating above a suction chamber (30B) for the gripper-free transport of printed sheets (D) from the grippers (33) of the printing cylinder (23), and in that each transfer conveyor (30) is arranged in a region moving the printed sheets (D) parallel to the sheet guide path (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 formed so as 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 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 transfer conveyors (30) are arranged above the printing cylinder (23) and the sheet guide track (28) in the first planar guide area (28a) so as to move away tangentially from the first printing cylinder (23) and to be guided parallel to the sheet guide track (28), and in that the transfer conveyors (30) are positioned such that the suction belts (30A) on the underside of the transfer conveyors (30) contact the upper side of the printed sheets (D) on the printing cylinder (23) and on the sheet guide track (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 at its inlet and outlet ends in the sheet travel direction (R) with openings (A) for the passage of grippers (33, 37) on the printing cylinders (23, 24), and in that the first printing cylinder (23) is arranged in the first flat guide region (28a) such that the grippers (33) are guided through the openings (A), and in that the second printing cylinder (24) is arranged in the third curved guide region (28c) such that the grippers (37) are guided through the openings (A).

9. Sheet-fed offset printing machine (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 transfer conveyors (30) on the upper side of the sheet guide track (28) to beyond the second flat guide area (28b). extend.

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 Generation of a conveying movement via the suction belts (29A), wherein the drive(s) 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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