EP2574463A1 - Sheet fed printing press - Google Patents

Abstract

The sheet-fed-printing machine has a sheet feeder, a printing mechanism and coating unit for printing on the printing sheet (B) with a statistical printing image identical for all printing sheets. An ionization device (7) is arranged in sheet travel direction (A) and towards a column (5) formed by a pressing device (4) and cylinder guiding the sheets and is arranged in front of the informal pressure device (8) against the surface of the cylinder guiding the sheets.

Description

The invention relates to a sheet-fed printing machine according to the preamble of claim 1.

In sheet-fed printing presses working according to the offset printing principle, use is increasingly being made of printing-form-free printing devices which are preferably used to individualize printed products produced by offset printing using, for example, barcodes, numbering or other markings. Such printing formless printing devices are also referred to as non-impact print (NIP) printing devices and can be embodied, for example, as inkjet printing devices which have at least one inkjet print head, wherein the or each inkjet print head according to the so-called continuous inkjet principle, The drop-on-demand inkjet principle, the thermal inkjet principle or any other inkjet principle can work. The pressure-formless or NIP printing devices can also be designed as laser printing devices.

Printing presses increasingly require the integration of different working steps in one machining operation. In addition to the classic flat gravure and high-pressure processes, new printing processes and various finishing steps of the print material. The combination of offset printing and flexographic printing is standard, and finishing steps such as cold foil transfer, embossing and stamping components are also partially realized. Currently, digital printing processes are increasingly entering the market, which are offered as a stand-alone application.

The present invention enables the use of high-quality digital printing systems, in particular for inkjet printing in the environment of a sheet-fed printing machine. The sheet to be printed can have very different mechanical properties, depending on the process conditions (printing speed, color assignment) the usually guided only at the leading edge sheet during transport does not hold on the impression cylinder surface, but take off, flutter or the end of the sheet will whip-like whipping. This leads to a reduction in duck quality with a fluctuating distance between the print head and the surface or disturbances in the printing due to impact of the freshly printed sheet. It is therefore essential that the sheet is held on the cylinder diameter or at a defined distance from the inkjet system.

From the DE 197 04 003 A1 a sheet-fed printing machine is known, in which a designed as an inkjet printing device or as a laser printing device, pressure-free printing device is integrated in an offset printing unit of the sheet-fed press. In this case, the pressure-formless printing device with respect to a sheet-guiding impression cylinder in the area after the passage of sheet is arranged by a pressure gap formed by the impression cylinder and a blanket cylinder. In the printing machine according to DE 197 04 003 A1 In particular, the printing of printed sheets with a high rigidity in the area of the inkjet printing device or laser printing device is problematic.

This is due to the fact that such sheets in the area of the sheet trailing edge after leaving the printing nip tend to bounce and so can change the distance between the printing form loose printing device and the sheet abruptly, which is why the sheet can strike without corresponding guide elements against the pressure-free printing device and Thus, the sheet in the area of the sheet trailing edge can not be printed with the same quality as in the area of a sheet leading edge and / or a sheet center.

To fix the sheets on the surface of the impression cylinder are in the DE 197 04 003 A1 Sheet guide rollers proposed, however, cover areas of the sheet, which is why the sheets can not be printed in this case of the formless printing device over the entire format width. Furthermore, the arrangement of the pressure-free printing device implies in the area of the printing nip that impressions are made in freshly printed sheet with the help of the pressure-free printing device, whereby the risk that the sheet guide rollers used leave marks on the surface of the sheet and thus affect the achievable print quality.

Another sheet-fed press with a built-in pressure-free printing device is from the DE 195 14 259 A1 known, the pressure-formless printing device seen in the transport direction of the sheet seen behind the last offset printing unit and in the transport direction of the sheet seen before a boom of the sheet-fed press integrated into the same according to this prior art.

From the DE 10 2006 002 302 A1 Another sheetfed press is known. For the purposes of the device described therein, it is proposed to integrate one or each printing device without pressure in the area of a sheet feeder of a sheet-fed printing machine into the same. Accordingly, in the context of this publication, the printing of printed sheets with the help of one or more pressure-free printing device at a time, which is prior to printing the sheet in the preferably formed as offset printing units of the sheet-fed printing press. Since the printed sheets to be printed in the area of the sheet feeder are flat and not curved as in the area of the printing units of the sheet-fed printing machine, the printing formless printing devices can be arranged with a small distance to the sheet without rolling on the sheet to be printed Sheet guide rollers are required, which on the one hand affect the print quality and on the other hand limit the printable in the range of or any pressure-free device width of the sheet.

From the DE 10 2006 002 304 A1 is another sheetfed press known. For the purposes of the device described therein, it is proposed to have one or more pressure-free printing devices in the region of a cantilever of a sheet-fed printing machine to integrate into the same. Accordingly, in the context of this publication, the printing of printed sheets with the help of or any pressure-free device at a time that is clearly after printing the sheet in the preferably designed as offset printing units of the sheet-fed printing press. Since the printed sheets to be printed in the region of the cantilever plane and not curved or aligned as in the printing presses of the sheet-fed press, the printing forme printing devices can be arranged with a small distance to the sheet without rolling on the printing side of the sheet Sheet guide rollers are required, which on the one hand affect the print quality and on the other hand limit the printable in the field of or any printing form loose device width of the sheet.

From the DE 10 2006 002 312 A1 is another sheetfed press known. For the purposes of the device described therein, one or more pressure-free printing devices are designed to be mobile or displaceable, so that they can be used on the one hand within the same sheet-fed printing machine at different installation positions and on the other hand on different sheet-fed presses. A pressure-formless printing device is therefore, if it should be done with the same at an installation position no printing of the sheet, from this installation position disassembled and therefore displaceable. Cleaning and maintenance work on pressure-free printing devices can thus be carried out independently of the sheet-fed press.

Furthermore, from the WO 2010/086205 A1 a sheetfed press known. The solution described there relates to a sheet-fed printing press, with a sheet feeder for feeding sheet to be printed in the sheet-fed press, with at least one printing unit and / or a coating unit for printing the sheet with a static, identical for all sheets printed image and further with a boom for discharging the printed sheet from the sheetfed press. In addition to the already existing printing units, there is at least one integrated pressure-free sheetfed press Printing device for printing the sheet with a particular dynamic and variable print image provided. For carrying out a printing method, it is provided that the or each pressure-formless pressure device is integrated into the sheet-fed printing press in conjunction with guide elements arranged opposite a sheet guiding surface. In particular, inkjet print heads are provided as pressure-free printing devices.

On this basis, the present invention is based on the problem to provide a novel sheet-fed printing machine.

This problem is solved by a sheet-fed printing machine according to claim 1.

According to the invention, the or each printing forme loose printing device is integrated in the sheet-fed cylinders in the sheet-fed printing press. The surface of the serving for the pressure-formless printing device as a counter surface cylinder is formed adhesive to accurately spaced the sheets to be printed and safely lead to the pressure-formless printing devices over.
For this purpose, an electrostatic device is mounted in a certain area of the printing press, preferably in the transport direction of the sheet in front of one or all pressure-free printing devices, by means of which a charge can be introduced into the sheet to be printed so that it adheres to the surface leading him.

Preferred embodiments of the invention will become apparent from the dependent claims and the description below.

In this case, in addition to designed as ionization electrostatic devices and a sheet guiding device for deriving the sheet to be printed from the calendering nip is provided.
If the smoothing nip is also used at the same time as a printing nip for printing a static image part, a blowpipe is preferably provided here on the outlet side of the printing nip. By means of the blowpipe become unwanted Movements at the sheet end of the sheet to be printed in the direction of the pressure-free printing device and a greasing already applied ink prevented.

Fig. 1

eine Bogendruckmaschine mit einer oder mehreren druckformlosen Druckeinrichtungen nach einem ersten erfindungsgemäßen Ausführungsbeispiel,

Fig. 2

eine anders konfigurierte Bogendruckmaschine zu einem zweiten erfindungsgemäßen Ausführungsbeispiel und

Fig. 3

eine detaillierte Darstellung der erfindungsgemäßen Anordnung einer druckformlosen Druckeinrichtung..

An embodiment of the invention will be described, without being limited thereto, with reference to the drawings described below. Showing:

Fig. 1

a sheet-fed printing press with one or more compression-free printing devices according to a first embodiment of the invention,

Fig. 2

a differently configured sheet-fed press to a second embodiment of the invention and

Fig. 3

a detailed illustration of the inventive arrangement of a pressure-formless printing device ..

Hereinafter, the present invention will be described with reference to FIGS Figures 1 and 2 initially described coarser.

Fig. 1 shows a schematic representation of a sheet-fed printing machine 10, wherein the sheet-fed printing machine 10 comprises a sheet feeder 11, a plurality formed as offset printing units 12, a printing units 12 downstream coating unit 13 and the coating unit 13 downstream boom 14. The sheet feeder 11 is used for feeding sheet to be printed in the sheet-fed press 10, wherein the sheets are moved through the printing units 12 and the coating unit 13 and printed in the same with a print sheet for all the same or unchanging and thus static printed image. In the area of the arm 14, printed signatures are discharged from the sheet-fed printing press to form a delivery stack 15. In the illustrated embodiment of the Fig. 1 is the sheetfed press 10 designed as a so-called turning machine, which serves the two-sided printing of printed sheets in the so-called perfecting. A arranged between the first two printing units 12 transfer cylinder is this formed as a turning cylinder 16.

In the sheet-fed printing machine 10, at least one pressure-formless printing device is integrated, which preferably serves to print the printed sheet with a dynamic or variable print image. The or each pressure-formless printing device can be integrated in the sheet feeder 11 in the sheet-fed press 10, wherein in Fig. 1 possible installation positions 17 and 18 are shown schematically for the or each pressure-formless printing device. In both installation positions 17 and 18, the printed sheets are printed in the area of the sheet feeder 11 via the or each pressure-formless printing device from above.

In the case in which the sheet feeder 11 is designed as a so-called single-sheet feeder, the installation position 18 is preferred for each pressure-formless printing device, namely above an investment table 19, via which printed sheets lifted from an feeder stack 20 are fed to the first printing unit 12 of the printing press. In the area of the investment table 19, the printed sheets are guided on their underside by at least one suction belt, so that the sheets of the or each printing form loose printing device on an upper side of the same are printable, namely over the entire format width and format length of the same. When transporting the printing sheet along the investment table 19, the sheets are flat or flat. It can be maintained a small distance between the or each printing form loose printing device and the sheet and thus a high print quality can be provided.

If, in the case of a sheet feeder 11 designed as a single-sheet feeder, a pressure-formless printing device is integrated in the installation position 18 above a support table 19 in the sheet feeder 11, the installation position along the support table 19 can be freely selected. For controlling the pressure-free printing device then at least a leading edge and a side edge of the sheet must be detected and evaluated to print the sheets in the desired zones of the same. The sensors required to detect the leading edge and side edge may be provided via infrared or ultrasonic sensors or capacitive sensors.

In the case in which the sheet feeder 11 is designed as a so-called flake feeder, the installation position 17 is preferred for the or each pressure-formless printing device, namely above an in Fig. 1 not shown investment sheet of the flaker feeder, wherein the sheet separated in the region of the contact plate and detected by a so-called pre-gripper 21 and the first printing unit 12 of the sheet-fed press 10 are supplied. Also in this case, the printed sheets of the or each printing formless printing device over the entire format width and format length can be printed with a dynamic or variable printed image.

If, in a sheet feeder 11 designed as a bulkhead feeder, a printing formless printing device is integrated in the installation position 17 adjacent to the pre-gripper 21 in the sheet feeder 11, then at least one leading edge of the print sheet must be detected and evaluated to control the printing formless printing device to the same in the desired zones to print. The required for detecting the leading edge sensor can be provided in turn via infrared or ultrasonic sensors or capacitive sensors. Between the pressure-free printing device 17 and the pre-gripper 21, a sheet guiding device is preferably positioned which can be displaced into regions or zones of the printed sheets which are not to be printed by the printing-formless printing device.

If the transport speed of the printed sheets changes over the pre-gripper 21 when the sheet is fed into the sheet-fed printing press, at least one characteristic line is preferably stored in a control device of the printing-formless printing device, which depends on substrate parameters such as the grammage and / or the fiber direction and / or the stiffness of the printed sheet is. The pressure-formless printing device is then controlled based on one of these characteristics. The characteristic curves are determined in advance for printed sheets from different substrates.

The or each in the sheet-fed printing machine 10 integrated pressure-free printing device is preferably designed as an inkjet printing device, such printing devices seen transversely to the transport direction of the sheet several juxtaposed inkjet printheads and seen in the transport direction of the sheet have several consecutively arranged inkjet printheads, the array-like or are arranged in a matrix-like manner to one another and are preferably interconnected on the control side.

The number of print heads required transversely to the printing direction is primarily defined by the desired total print width relative to the given print width of the print head used.

The required number of printheads in the transport direction of the sheet is, however, determined by the fact that the desired printing speed is greater than the given printing speed of a printhead and in that a plurality of inks are to be applied to the sheets by means of pressure-free printing device. Furthermore, the number of print heads in the transport direction of the print sheets is defined by the desired print resolution in relation to the given print resolution of the print head used.

As already mentioned above, serve the printing units 12 and the coating unit 13 of the sheet-fed printing machine 10 of the embodiment of the invention Fig. 1 printing on the printed sheets with a static, identical for all sheets printed image. The or each integrated in the sheetfed press 10 in the sheet feeder 10 pressure-free device, however, serves to print the sheet with a dynamic or variable print image, the printing with the dynamic or variable print image inline for printing the printing sheet with the static print image takes place, namely before the printing of the printed sheets in the printing units 12 and the coating unit 13. In addition pressure-free printing devices can be provided in mounting positions 30, 31 on counter-pressure cylinders 40 in printing units 12. In this case, the pressure-formless printing devices are arranged downstream of a printing gap serving as ink transfer on the printing sheet in the sheet running direction.
Furthermore, it can also be provided for an installation position 32 on a counter-pressure cylinder 40 in a coating unit 13, a pressure-formless printing device. Furthermore, pressure-formless printing devices in installation positions 33, 34 may be provided on sheet guides 41 in the boom 14, so that they act on the underside of the sheet.

The compression-free printing devices are not intended for use in the Fig. 1 shown configuration of a sheet-fed press limited, but they can be used in any sheetfed presses. So shows Fig. 2 an application in a sheet-fed printing machine 22, as viewed in the transport direction of the sheet after the sheet feeder 11 designed as a flexographic printing unit 23 and seen in the transport direction of the sheet before the boom 14 a coating unit 24 is arranged, and wherein between the flexographic printing unit 23 and the coating unit 24th two drying devices 25 are positioned.

Also in the embodiment of Fig. 2 is integrated into the sheet-fed press 22 at least one printing forme pressure device in the region of the sheet feeder 11, namely either in the field of installation position 17 or in the field of installation position 18, so that the comments on the embodiment of Fig. 1 can be referenced. As already in connection with the embodiment of Fig. 1 mentioned, the mounting position 17 is preferred in a sheet feeder designed as a sheet feeder and the mounting position 18 in a sheet feeder designed as a sheet feeder.
Furthermore, printing formless printing devices can also this sheet-fed printing press 22 in installation positions 32 on impression cylinders 40 in the printing units 23, 24 may be provided which are designed in the manner of flexographic printing units or coating units.
Furthermore, pressure-formless printing devices may be provided in an installed position 35 on sheet guides 42 in the boom 14 so that they act on the printed sheets from the top.

The variants for the arrangement of pressure-free printing devices in the boom 14 after Fig. 1 and 2 are each possible in the other embodiment shown here in all machine configurations.

Likewise, pressure-formless printing devices can be used in sheet-fed presses, in which the sheet feeder is designed as a roll-sheet feeder. The roll sheet feeder includes a sheet cutter and is also referred to as an inline sheeter. In the sheet-cutting device are cut from a web-shaped substrate sheet, which are then fed via an investment table the first printing unit of the following sheet-fed press. In the reel-to-sheet feeder, the or each pressure-formless printing device is preferably integrated at the installation position in the sheet feeder, where the sheets are guided horizontally over a conveying surface and are largely accessible from above.

According to an advantageous embodiment, the or each printing plateless printing device of the sheet printing machine is removable, in such a way that the or each of the printing form loose printing devices on another sheet printing machine 10, 22 or within the same sheet-fed press 10, 22 can be used in different mounting positions.

For this purpose, the or each of the pressure-free printing devices each have an interface that is designed for supply, namely mechanical or Druckfarbeneseitigem way, and an interface that is used for control, namely in relation to electrical or electronic operations and over the or Each of the pressure-free printing devices to a system for supply Printing colors or can be connected to a control device of the respective printing press.

If such formless printing devices have been integrated into a sheet-fed printing machine 10, 22 at several installation positions, the electrical and mechanical interfaces for these printing devices can be centralized at one point of the sheet-fed printing machine 10, 22. To the or each pressure-formless printing device leading supply lines, be it electrical supply lines or mechanical or printing ink side supply lines can either be permanently installed on the sheet-fed press according to the invention or mobile to the sheet-fed press 10, 22 are introduced. Due to the disassembly of the or each printing formless printing device of the sheet-fed printing machine according to the invention maintenance and cleaning of the printing formless printing devices outside the range of the sheet-fed press 10, 22 can be performed.

When viewed in the direction of transport of the printing sheet, the printing formless printing device is preferably arranged downstream of a drying device or curing device and / or a suction device, wherein the drying device serves to dry the printing ink applied via the printing formless printing device and the suction device to remove solvent vapors from the ink applied via the printing plate free printing device.

Compression-free printing devices may also be pivotally mounted in the area of the sheet feeder 11 (e.g., mounting position 17 and / or 18), preferably on a pivot arm engaging a side frame of the sheet feeder 11 or the first printing unit. As a result, the sheet feeder 11 is freely accessible for setup work.

The embodiment of a pressure-free printing device according to the invention in a printing unit of a printing press is described with more details with reference to Fig. 3 described.

In the FIG. 3 illustrated embodiment allows the use of high-quality digital printing systems, in particular by the method of inkjet printing in the technical environment of a sheet-fed press.

For processing in the printing process, a printing sheet B in a processing unit 1 on the smooth surface of a impression cylinder 2 resting and transported at its front edge by grippers 3 in the working direction A is transported. For processing the counter-pressure cylinder 2 - see also the arrangements of counter-pressure cylinders 40 in Fig. 1 and 2 - Assigned in the treatment plant 1, a pressing device.

The pressing device is designed here as a pressure roller 4, but can also be performed depending on the configuration of the processing plant 1 as a blanket cylinder, blanket cylinder, forme cylinder or pressure roller.

The pressure roller 4 forms a pressure nip 5 with the impression cylinder 2, so that there the sheet B of the pressure roller 4 is smoothly placed on the surface of the impression cylinder 2. In order to support the smooth support of the printing sheet B, a blowing tube 6 is arranged on the outlet side of the printing gap 5 located in the working direction A of the machine movement, the blowing air jet of which blows into the printing gap 5. In this way, an evasive movement of the printed sheet B upon exiting the printing nip 5 can be prevented.

Downstream of the blowpipe 6, an ionizer 7 is arranged opposite the surface of the counter-pressure cylinder 2. In this way, a printed sheet B resting on the counter-pressure cylinder can be charged by means of contact-free charged charged particles, so that it subsequently firmly adheres to the impression cylinder 2 by means of the electrostatic effect.
So that the charged particles can be held in the printed sheet B, an insulating support sheet 2A can be applied to the impression cylinder.

Downstream of the ionizer 7 in the working direction A, an inkjet print head 8 is arranged, by means of which the print-form-free image parts can be applied to the print sheet B, while the print sheet B is held completely flat against the impression cylinder 2.

In order to enable the sheet transport for the sheet delivery in best form, the inkjet printhead 8 downstream in the direction A of the impression cylinder 2 a de-ionizer 9 is assigned. By means of the de-ionizer 9, the electrostatic charge of the sheet is reduced again, so that disturbances in the sheet transport can be minimized.

The function of the arrangement according to the invention is justified as follows. In principle, a printed sheet B, as used for example in sheetfed offset printing, have very different mechanical properties. It follows that, depending on the prevailing process conditions within the selected printing press depending on the printing speed, the number of process steps, the mechanical properties of the sheet B or the color assignment on the sheet B, this is subject to different stresses. As in Fig. 3 shown, the sheet B is usually guided at its front edge of grippers 3 and can not always be held securely on the surface of the impression cylinder 2 due to the stress during transport. It may come as a result of the stresses that the sheet B lift off, flutter or that he will beat at its end of the sheet.
The measures described in the solution according to the invention serve to ensure that the printed sheet B rests on the circumference of the cylinder, for example on the impression cylinder 2 and that it is at a defined distance from an inkjet print head 8 (see also the installation positions 30, 31 and 32 in FIG Figures 1 and 2 ) can be maintained to optimize the printing conditions of the inkjet printhead 8.

After the Figures 1 and 2 the following is to be stated:

If the printed sheet in a printing unit, which is shown here in the form of printing units 12 or as coating unit 13 or flexographic printing unit 23 or coating unit 24, digitally printed, this is done by the sheet is guided on grippers on a counter-pressure cylinder 40. Thus, it is possible, similar to an offset printing unit, to arrange a guide cylinder 50 in the manner of a forme cylinder or blanket cylinder in front of the inkjet print head, thereby pressing the signature B onto the surface of the impression cylinder 40.

This application is also possible in the conventionally executed printing units 12, coating units 13, flexographic printing units 23 or coating units 24, which can also be used in their normal function without inkjet application.

Unlike in normal printing units but also the surface of a impression cylinder 40 can be equipped with elastic and functional elements that cause adhesion of the sheet on the cylinder surface. Then it is provided that the corresponding printing unit 12, 13, 23, 24 is used only for inkjet printing.

According to the invention, electrostatic processes should now also be used for sheet adhesion to the impression cylinder 2. The description refers to a processing plant 1, whose configuration is described above with reference to FIG. 3 was explained.

The printed sheet B is electrically charged with respect to its electrically conductive base, which is formed here by a counter-pressure cylinder 2, with a relatively high voltage of up to several 10,000 volts. As a result, the printed sheet B is attracted by the electric field of the pad, so the surface of the impression cylinder 2, so strong that it is pressed downright on the cylinder surface. The charging can be effected without contact by flowing, ie free-flying, electrons which are generated by corona discharge or peak discharge or plasma discharge or other discharge processes. After the processing unit 1, the sheet B can then unload again become. For this purpose, on the one hand an ionization device is provided as an ionizer 7 associated with the impression cylinder 2 and on the other hand, a de-ionizer 9 is arranged opposite the impression cylinder surface.

By the aid of electrostatic charging of the printing sheet B, the generation of a holding force between the underside of the paper surface of the printing sheet B and the cylinder surface, ie the outside of the impression cylinder 2, is possible. This ensures that the printed sheet B and in particular the sheet end of the held by the gripper 3 at the leading edge of printed sheet B adhere to the cylinder surface. The targeted charge distribution in the printing material leads to a polarization between the paper surface and the cylinder surface. This results in a clearly detectable attraction between the relatively large surfaces of the two elements sheet B and impression cylinder. 2
By the above-mentioned attachment of an insulating film 2A acting on the surface of the impression cylinder 2, the adhesion can be supported because the support film 2A obstructs the flow of electrical charges from the sheet B on the impression cylinder 2.

If the printing sheet B was quasi ironed in a nip 5 between a pressure roller 4 and the impression cylinder 2 by being pressed by a printing operation or by rolling a pressure roller formed as a blanket cylinder 4, a wrinkle-free installation of the sheet B on the cylinder surface is possible. In this connection, a so-called Druckzylinderblasvorrichtung, which is arranged in front of the printing nip 5, can be used to assist.

Furthermore, the arrangement of a blower tube 6 between the pressure nip 5 and the ionizer 7 is helpful when it comes to a running, ie adhesion of the sheet to the pressure roller 4 or the blanket cylinder or the forme cylinder. This danger exists in particular when the pressure roller 4 is designed as a blanket cylinder and is operated color leading and the printed Paper side adheres to the cylinder surface. With the action of a blown air jet 6A, the printed sheet B is removed from the blanket cylinder prior to ionization and ironed onto the impression cylinder 2.

In order to support the clean sheet travel without adherence of the sheet B to guide elements, a de-ionization with the aid of the de-ionizer 9 is possible behind the non-contact inkjet printhead 8. In order for a possibly relatively large adhesive force of the sheet B is reduced with respect to the counter-pressure cylinder 2 leading him and allows a clean detachment of the sheet B from the impression cylinder 2 to further transporting facilities.

Furthermore, a modification of the impression cylinder surface has a supporting effect. A coating or a coated elevator, such as in the manner of the above-mentioned support film 2A, can also be used to increase the cylinder diameter. In addition, this measure, in addition to the obstruction of the charge discharge and the charge distribution is favorably influenced. Such a non-conductive plastic layer supports the polarization and thus also the adhesion of the printing sheet B is reinforced on the impression cylinder 2. Furthermore, a sufficient adhesive effect for the printing process can be achieved even with a reduced impact strength or exposure time by means of the ionizer 8.

The device according to the invention for the ionization of printed sheets after a printing nip described here can also be used in conjunction with an sheet inspection device or a color measuring device which is arranged at the location of the inkjet printing head. Then, the same advantageous effect of the adhesion of the sheet end to the cylinder surface of the impression cylinder after exiting the printing nip for the measurement on the surface of the printing sheet occurs.

LIST OF REFERENCE NUMBERS

1

Cutting

2

Impression cylinder

2A

overlay sheet

3

grab

4

pressure roller

5

nip

6

blowpipe

6A

air jet

7

ionizer

8th

Inkjet printhead

9

De-ionizer

10

Sheetfed

11

sheet feeder

12

printing unit

13

coating unit

14

boom

15

delivery pile

16

turning cylinder

17

pressure-free printing device / installation position

18

pressure-free printing device / installation position

19

feed table

20

feeder pile

21

pregrippers

22

Sheetfed

23

printing unit

24

coating unit

25

drying device

26

Sheetfed

27

Bow Roll-Schneieinrichtung

28

role

29

pressure-free printing device / installation position

30

pressure-free printing device / installation position

31

pressure-free printing device / installation position

32

pressure-free printing device / installation position

33

pressure-free printing device / installation position

34

pressure-free printing device / installation position

35

pressure-free printing device / installation position

40

pressure cylinder

41

Sheet guiding device

42

Sheet guiding device

Claims (10)

Sheet-fed printing machine (10, 22), with a sheet feeder (11), with at least one printing unit (12; 23) and / or coating unit (13; 24) for printing on printed sheets (B) with a static, for all printed sheets (B) identical Printed image, with a boom (14) and with at least one in the sheet-fed press (10, 22) integrated pressure-free printing device (8, 17, 18, 29, 31-35) for printing the printed sheet (B) with a particular dynamic, variable printed image,
in that the or each printing-form-free printing device (8, 17, 18; 29; 31-35) is integrated in the sheet-fed printing press in the area of sheet-guiding cylinders (2, 40) and in that the sheet-guiding cylinders (2, 40) are flat Adhesive guiding the printing sheet (B) are provided, wherein the sheet leading cylinder (2, 40) is provided with an electrically conductive surface and that the sheet guide of the sheet (B) is associated with a charging device for electrostatic charging of the printed sheets, so that at least the the printing-form-free printing device (8, 17, 18, 29, 31-35) being subjected to electrostatically attracted to opposite parts of the printed sheets (B) by the sheet-guiding cylinder (2, 40), characterized
in that, in the sheet running direction (A), an ionization device (7) projects downstream of a printing nip (5) formed by a pressure device (4) and the sheet (2, 40) and in front of the pressure - free printing device (8, 30 - 32) relative to the surface of the printing device Arc leading cylinder (2, 40) is arranged. Sheet-fed printing machine according to claim 1,
characterized,
in that the pressure device is formed by a pressure roller (4), wherein the pressure roller (4) can be designed as a blanket cylinder, a form cylinder, a blanket cylinder or a pressure roller. Sheet-fed printing machine according to claim 1 or 2, characterized
in that a blowing device (6) is provided in the sheet running direction (A) in front of the ionization device (7), the blowing jet (6A) of which is directed into the printing nip (5) and onto the surface of the guided printing sheet (B). Sheet-fed printing machine according to claim 1 to 3, characterized
that in the sheet running direction (A) after the ionization device (7) and prior to separation of the printing sheet (B) leading from the sheet cylinder (2, 40) is provided a de-ionization device (9), the effect (on the surface of the guided recording sheet B ) is directed so that its adhesive force on the arc leading cylinder (2, 40) is reduced. Sheet-fed printing machine according to Claims 1 to 4, characterized
in that an electrically insulating support foil (2A) is provided on the surface of the sheet-guiding cylinder (2, 40) in such a way that a charge discharge from the charged printed sheet (B) is reduced to the sheet-guiding cylinder (2, 40) and a homogenization of the Charge distribution over the surface of the print sheet (B) is generated. Sheet-fed printing machine according to claims 1 to 5, characterized in that
in that an electrically insulating support foil (2A) is provided on the surface of the sheet-guiding cylinder (2, 40) in such a way that a charge discharge from the charged printing sheet (B) to the sheet-guiding cylinder (2, 40) is reduced. Sheet-fed printing machine according to claim 6, characterized
in that an electrically insulating support foil (2A) is provided on the surface of the sheet-guiding cylinder (2, 40), such that the diameter of the sheet-guiding cylinder (2, 40) for approaching the printing sheet (B) to the pressure-formless printing device (8 , 30-32) is enlarged. Sheet-fed printing machine according to claim 1 to 6, characterized in that in a control device of the printing formless printing device (8; 30 - 32) deposited at least one characteristic which is dependent on printing material characteristics such as the grammage and / or the fiber direction and / or the stiffness of the printed sheet, wherein the pressure-formless printing device (8; 30-32) is controllable on the basis of these characteristics. Sheet-fed printing machine according to one or more of claims 1 to 7, characterized in that the or each pressure-formless printing device (8; 30-32) is designed as an inkjet printing device, wherein the printed sheets (B) over the entire format width and / or format length of the or any printing formless printing device (8; 30-32) are printable. Sheet-fed printing machine according to claim 8, characterized in that the or each pressure-formless printing device (8; 30-32) seen transversely to the transport direction of the print sheet has a plurality of juxtaposed inkjet printheads and / or seen in the transport direction of the print sheet a plurality of successively arranged inkjet printheads, the are interconnected on the control side.

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