Sheet-fed printing machine with a screen printing unit and a sheet cleaning device

Abstract

The invention relates to a sheet-fed printing press with a sheet feeder and at least one screen printing unit, wherein the screen printing unit has at least one first application point which is formed by an impression cylinder and a first screen printing form cylinder, and wherein a sheet feed device of the sheet-fed printing press has at least one sheet transport means designed as a suction drum, and wherein the sheet-fed printing press has at least one first transfer drum which is arranged along a transport path provided for transporting sheets downstream of the suction drum and upstream of the impression cylinder and which has at least one gripper system, and wherein the sheet-fed printing press has at least one sheet cleaning device,in whose area of ​​action the transport path provided for the transport of sheets is defined by the first transfer drum and wherein the sheet cleaning device has, along the transport path provided for the transport of sheets, in succession at least one discharge electrode, a first brush strip, a suction opening and a second brush strip.

Description

The invention relates to a sheet-fed printing press according to the preamble of claim 1.WO 2022 / 228822 A1 discloses a sheet-fed printing press having a screen printing unit and an alignment device.DE 1 636 315 A1 discloses a sheet-fed printing press having a sheet-cleaning device.EP 1 464 491 A2 discloses a sheet-fed printing press having a sheet-cleaning device.The object of the invention is to provide a sheet-fed printing press having a screen printing unit and a sheet cleaning device.The object is achieved according to the invention by the features of claim 1.A sheet-fed printing press has at least one sheet feeder and at least one screen printing unit. The screen printing unit has at least one first application point which is formed by an impression cylinder and a first screen printing forme cylinder, in particular a first screen printing forme cylinder interacting therewith. A sheet-feeding device of the sheet-fed printing press has at least one sheet-feeding means designed as a suction drum. The sheet contact device is preferably arranged downstream of the sheet feeder and / or upstream of the screen printing unit. The sheet-feeding device of the sheet-fed printing press has at least one sheet-transport means designed as a suction drum. The sheet-fed printing press has at least one first transfer drum which is arranged downstream, in particular directly downstream of the suction drum and upstream of the impression cylinder, along a transport path provided for transporting sheets, and which has at least one gripper system, for example at least one gripper bar. The sheet-fed printing press has at least one sheet-cleaning device, in the active region of which the transport path provided for the transport of sheets is defined by the first transfer drum. The sheet cleaning device has at least one discharge electrode, a first brush strip, a suction opening and a second brush strip in succession along the transport path provided for the transport of sheets.An advantage of such a sheet-fed printing press is, in particular, that an optimized alignment, which protects the material, can be carried out by the suction drum, while the effect of the suction of the sheet-cleaning device is not in competition with the effect of the suction drum, since the sheet-cleaning device is aligned with the following transfer drum, on which the sheets are held by means of grippers.In a further development, the sheet-fed printing press is preferably characterized in that the sheet-feed device has at least one movable front stop which is arranged in a switchable manner between an alignment position interrupting the transport path provided for the transport of sheets and a passing position releasing the transport path provided for the transport of sheets. As a result, a particularly effective and rapid alignment of the sheets can take place.In an alternative or additional refinement, the sheet-fed printing press is preferably characterized in that the at least one discharge electrode is arranged connected to at least one DC voltage source for the purpose of supplying voltage. This achieves a particularly efficient discharge of dirt particles adhering to the sheet.In an alternative or additional development, the sheet-fed printing press is preferably characterized in that the sheet-cleaning device has a housing, relative to which the discharge electrode, the first brush strip and the second brush strip are arranged in a fixed position and which is arranged connected to a machine frame of the printing press via a position-adjusting device, and in that a distance between the discharge electrode and the first transfer drum can be adjusted by means of the position-adjusting device. Thus, an adaptation to printing materials of different thicknesses and / or different cleaning requirements can be effected.In an alternative or additional development, the sheet-fed printing press is preferably characterized in that the sheet-cleaning device has a cavity which extends over at least 80% of the working width of the sheet-fed printing press, and in that the suction opening connects an outer region to the cavity, and in that the suction opening extends over at least 80% of the working width of the sheet-fed printing press. This allows uniform suction with a relatively simple embodiment of the sheet cleaning device.In an alternative or additional refinement, the sheet-fed printing press is preferably characterized in that the sheet-fed printing press has at least one alignment device which is designed as a magnetic cylinder having a plurality of magnetic elements. This makes it possible to produce particularly forgery-proof printed products, in particular security papers.In an alternative or additional development, the sheet-fed printing press is preferably characterized in that the sheet-fed printing press has a multiple stack delivery with a plurality of delivery regions. It is thus possible to produce without interruption and / or to discharge waste easily.In an alternative or additional development, the sheet-fed printing press is preferably characterized in that the screen printing unit has the first application point which is formed by the impression cylinder and the first screen printing forme cylinder which interacts in particular therewith, and in that the screen printing unit has a second application point which is formed by the same impression cylinder and a second screen printing forme cylinder which interacts in particular therewith. This allows a particularly register-based printing with a plurality of colors and / or printing patternsAn exemplary embodiment of the invention is illustrated in the drawings and is described in more detail below.The following are shown: FIG. 1a is a schematic illustration of a sheet-fed printing press; FIG. 1 bshows an enlarged illustration of a partial region from FIG. 1 a; FIG. 2 shows a schematic illustration of a substrate printed in printing elements with optically variable coating agent, wherein a) shows a state with magnetic or magnetizable particles not yet oriented and b) shows a state after an imaging part has been aligned, here exemplarily in the form of a numeral "1"; FIG. 3 shows a schematic illustration of a printing and downstream alignment process with an image-forming printing couple cylinder and a cylinder having magnetic elements, illustrated by way of example with a substrate sheet widening trapezoidally toward the trailing end; FIG. 4 is a schematic oblique view of an embodiment for a cylinder having magnetic elements; FIG. 5 shows a schematic illustration of a transfer drum and a sheet cleaning device in a side view; FIG. 6 shows a schematic illustration of a transfer drum and a sheet cleaning device in a view counter to a transport direction.A printing machine 01 configured as a screen printing machine 01 will be described below. The printing press 01 is preferably designed as a sheet-fed printing press 01. The printing press 01 is preferably designed as a security printing press 01. The printing press 01 is preferably designed as a printing press 01 for producing optically variable image elements 03 on a substrate 02, also referred to as a printing substrate 02. The printing press 01 has at least one printing unit 04 designed as a screen printing unit 04. The printing unit 04 has at least one application point 31; 32, in particular at least one first application point 31. The respective at least one application point 31; 32 serves to apply a coating agent 06, which is embodied, for example, as a printing ink 06 or varnish 06, to at least one first side of the substrate 02, for example, over the entire surface or in partial regions in the form of printed image elements 08. The coating agent 06 is preferably designed as an optically variable coating agent 06, in particular as an optically variable printing ink 06 or optically variable lacquer. Preferably, each applicator 31; 32 is assigned to a respective printing unit 11; 12.The printing press 01 preferably has at least one alignment device 07 for aligning particles P contained in the optically variable coating agent 06 applied to the substrate 02 and responsible for the optical variability. This alignment device 07 is, for example, an image-forming alignment device 07, since it preferably serves to bring about an image formation for the optically variable pattern or motif by defined alignment of the particles P. (A coating composition 06 containing particles P is applied to the substrate 02 and a picture element 03 obtained by subsequent image-forming alignment of previously randomly oriented particles P is schematically shown in FIG. 2 by way of example with reference to a representation of the number "1.". Here, a) represents a state in which the coating agent 06 is applied and is still present, for example, in a randomly oriented state, and b) represents a state in which image-forming orientation has taken place.)The printed image elements 08 of variable coating agent 06 applied to the substrate 02 by means of the printing unit 04 before the treatment by the alignment device 07 can correspond in size and position to the optically variable image elements 03 to be produced or, if appropriate, can also be larger than these, optionally even extend over the surface of a plurality of panels 09. In the case of larger printed image elements 08, for example, an optically variable image element 03 is not produced on the entire surface coated with optically variable coating agent 06 by alignment.Particles P responsible for the optical variability are contained in the coating agent 06, for example, magnetic and / or magnetizable, non-spherical particles P, for example pigment particles P, also referred to below for short as magnetic flakes.In particular, a transport path provided for transporting substrate 02 is defined by printing machine 01. The transport path provided for transporting substrate 02 is in particular that spatial region which substrate 02 possibly assumes and / or would assume at least temporarily as intended in the case of its presence.A transport direction T is preferably in each case that direction T, in particular in the case of a curved transport path, which extends tangentially to a section and / or point of the provided transport path closest to a respective reference point and is provided for the transport of the substrate 02 at this section and / or point. This respective reference point is preferably located at the point and / or at the component which is related to the transport direction T. The transport direction T accordingly preferably extends in each case along the transport path provided for the transport of substrate 02. A transverse direction A is preferably a horizontal direction A which is oriented orthogonally to the transport direction T.A working width of the printing machine 01 is preferably a dimension that preferably extends in the transverse direction A. The working width of the printing press 01 preferably corresponds to a maximum width which a substrate 02 may have in order to be able to print with the printing press 01, that is to say in particular a maximum sheet width and / or width of the substrate 02 that can be processed with the printing press 01. The width of a substrate 02 is to be understood here in particular as its dimension in the transverse direction A. The working width of the printing press 01 is, for example, at least 20 cm, preferably at least 50 cm and more preferably at least 100 cm.The printing press 01 is preferably designed for producing useful papers 09, for example security papers 09, in particular bank notes 09. This is intended to include, in particular, the production of intermediate security papers, for example the production of printing material 02, in particular in the form of sheet-shaped printing material sections 02, in particular printing material sheets 02, with printed images of a plurality of security papers 09. The substrate 02 can be formed by paper, e.g. cellulose-based or preferably cotton fiber-based or at least containing paper, by plastic polymer or by a hybrid product thereof. The substrate 04 may be uncoated or may have already been coated in the at least one printing unit 04 before printing. The substrate 04 may have been unprinted in the at least one printing unit 04 before printing or may have already been printed one or more times in one or more upstream processes or mechanically processed in some other way. On a respective sheet 02 of the substrate 02, a plurality of panels 09, e.g. bank notes 09 to be produced or their printed images, are preferably arranged in a matrix-like manner, next to one another in rows running transversely to the transport direction T and in columns running in the transport direction T, or arranged one behind the other in the course of the processing of the substrate 02 (indicated, for example, in FIG. 2 and in FIG. 3 ).The printing press 01 has at least the at least one printing unit 04, preferably designed as a screen printing unit 04, having at least one and preferably a plurality of printing units 11; 12. For example, the printing press 01 additionally has at least one further printing unit which is designed to operate according to any desired printing method. The printing press 01 preferably has a printing unit 04 having at least one printing unit 11; 12 which operates according to screen printing methods and by means of which the optically variable coating agent 06 is or can be applied to a first side of the substrate 02. The screen printing method makes it possible, for example, to apply a greater layer thickness than other printing methods. The expression of the "first side" of the substrate 02 or of the printing substrate 02 is arbitrarily chosen here and, for example, a side of the substrate 02 lying on top of a feed stack 57 of a sheet feeder 13. This first side is preferably that side of the substrate 02 on which optically variable coating agent 06 to be treated downstream by an alignment device 07 is or can be applied.The screen printing unit 04 has at least one impression cylinder 17 and preferably exactly one impression cylinder. The screen printing unit 04 has at least one first application point 31, which is formed by the at least one impression cylinder 17 and a first screen printing forme cylinder 14 cooperating therewith in particular.The screen printing unit 04 preferably has two screen printing units 11; 12. Each screen printing unit 11; 12 preferably has a forme cylinder 14; 16 preferably designed as a screen printing forme cylinder 14; 16. Each forme cylinder 14; 16 preferably forms an application point 31; 32 with an impression cylinder 17. In particular, the screen printing unit 04 preferably has an impression cylinder 17, two forme cylinders 14; 16 and two application points 31; 32. The screen printing unit 04 preferably has the first application point 31, which is formed by the impression cylinder 17 and the first screen printing forme cylinder 14 cooperating in particular therewith. The screen printing unit 04 preferably has a second application point 32, which is formed by the same impression cylinder 17 and a second screen printing forme cylinder 16 cooperating in particular therewith.The respective forme cylinder 14; 16 preferably has a multiplicity of, in particular identical and / or identical, image-forming printing elements 18, which are also referred to as print subjects 18, for example. For example, the respective forme cylinder 14; 16 has a plurality of, in particular identical and / or identical, groups of image-forming printing elements 18 or print subjects 18 on the circumference, which are arranged on a circumferential length corresponding to the print image length in a plurality of, for example a number, for example from four to eight, in particular five to seven, for example six, columns spaced apart from one another transversely with respect to the circumferential direction of the forme cylinder 14; 16 and on a cylinder width corresponding to the print image width in a plurality of rows spaced apart from one another in the circumferential direction of the forme cylinder 14; 16. These printed media 18 are in the preferred case of a screen printing forme cylinder 14; 16 in the form of print-through stencils.The printing press 01 has at least one substrate source 13, which is preferably designed as a sheet feeder 13. The sheet feeder 13 serves in particular to remove sheets 02 from a feeder stack 57 for further transport and to separate them at least partially. The sheet feeder 13 preferably has a sheet separating device 53 with at least one separating sucker 54 and at least one transport sucker 56. This makes it possible to produce an overlapping stream of sheets 02 which can be aligned and accelerated for transport through the sheet-fed printing press 01.The printing press 01 preferably has a sheet-feeding device 28, which is arranged in particular downstream of the sheet feeder 13 and / or upstream of the screen-printing unit 04. The sheet-placement device 28 serves in particular to align at least partially separated sheets 02 and to speed them up to a machine speed in particular. The sheet-feeding device 28 preferably also serves to completely separate sheets 02 transported in overlapping fashion up to then. The sheet-feeding device 28 of the sheet-fed printing press 01 has at least one sheet-feeding means 33 designed as a suction drum 33. In particular, the suction drum 33 preferably has no grippers. The sheet contact device 28 preferably has at least one movable front stop 47, which is arranged in a switchable manner between an alignment position interrupting the transport path provided for the transport of sheets 02 and a passing position releasing the transport path provided for the transport of sheets 02. Preferably, the at least one movable front stop 47 is arranged in its alignment position at a distance of less than a sheet length from the suction drum 33.The sheet-fed printing press 01 has at least one first transfer drum 34, also referred to as receiving drum 34, which is arranged after the suction drum 33 along the transport path provided for the transport of sheets 02 and preferably directly after the suction drum 33, and which is arranged before the impression cylinder 17 along the transport path provided for the transport of sheets 02. For example, this first transfer drum 34 forms a transfer point with the suction drum 33. This first transfer drum 34 has at least one gripper system 38 which is designed, for example, as at least one gripper bar 38.The sheet-fed printing press 01 preferably has at least one second transfer drum 58, which is arranged along the transport path provided for the transport of sheets 02 downstream of the first transfer drum 34 and preferably directly downstream of the first transfer drum 34, and which is arranged along the transport path provided for the transport of sheets 02 upstream of the impression cylinder 17 and preferably directly upstream of the impression cylinder 17. For example, this second transfer drum 58 forms a transfer point with the first transfer drum 34.The sheet-fed printing press 01 has at least one sheet-cleaning device 41 in the active region 59 of which the transport path provided for the transport of sheets 02 is defined by the first transfer drum 34. This at least one sheet cleaning device 41 is thus preferably arranged in a manner sufficient to the first transfer drum 34. The sheet cleaner 41 has at least one discharge electrode 42. This at least one discharge electrode 42 is preferably arranged connected to at least one DC voltage source 48 for the purpose of supplying voltage. The sheet cleaning device 41 has at least one first brush strip 43. The sheet cleaning device 41 has at least one second brush strip 44. These brush strips 43; 44 preferably extend in the transverse direction A over the entire working width of the printing press 01. The sheet cleaning device 41 has at least one suction opening 46. In particular, the sheet cleaning device 41 has at least one discharge electrode 42, a first brush strip 43, a suction opening 46 and a second brush strip 44 in succession along the transport path provided for the transport of sheets 02. The suction opening 46 is thus preferably arranged between the first brush strip 43 and the second brush strip 44. The brush strips 43; 44 preferably have brushes made of polyamide, in particular in order to increase their mechanical and chemical resistance.Sheet cleaning device 41 preferably has a cavity 53 which extends over at least 80%, more preferably at least 90%, and even more preferably at least 100% of the working width of printing press 01. The suction opening 46 preferably connects an outer region to this cavity 53. Preferably, the suction opening 46 extends over at least 80%, more preferably at least 90%, and even more preferably at least 100% of the working width of the printing press 01. For example, a suction line is connected laterally to the cavity 53. For example, this suction line is connected to a suction device.The sheet cleaning device 41 preferably has a housing 49, relative to which the discharge electrode 42, the first brush strip 43 and the second brush strip 44 are arranged in a fixed position. The housing 49 is preferably arranged connected to a machine frame 52 of the printing machine 01 via a position adjustment device 51. Preferably, a distance between the discharge electrode 42 and the first transfer drum 34 is adjustable by means of the position adjusting device 51. For example, the position adjusting device 51 has at least one stop, whose position can be adjusted in particular by means of at least one thread, against which the housing 49 can be arranged acted upon by a force. In particular, the discharge electrode 42 can be selectively arranged in different positions by means of the position adjusting device 51, which differ at least with regard to the respective minimum distance between the discharge electrode 42 and the first transfer drum 34.The transport path provided for transporting substrate 02 preferably runs starting from substrate source 13 up to a substrate delivery device 22 of printing machine 01. This substrate delivery device 22 is designed, for example, as a stack delivery device 22 and preferably as a multiple stack delivery device with a plurality of delivery regions 39. Along the transport path provided for transporting the substrate 02, at least the screen printing unit 04 is arranged. Preferably, the at least one alignment device 07 is arranged in particular along the transport path provided for the transport of substrate 02 downstream of the screen printing unit 04.Preferably, a first conveying device 19 is arranged, by means of which the transport path provided for the transport of substrate 02 from screen printing unit 04 and in particular from its impression cylinder 17 to alignment device 07 is defined. This first conveying device 19 has, for example, one or more transfer cylinders with grippers. However, this first conveying device 19 is preferably designed as a circulating gripper conveyor 19, in particular as a chain gripper system 19.Preferably, a second conveying device 21 is arranged, by means of which the transport path provided for the transport of substrate 02 from the alignment device 07 to the substrate delivery device 22 is defined. This second conveying device 21 has, for example, one or more transfer cylinders with grippers. However, this second conveying device 19 is preferably designed as a circulating gripper conveyor 21, in particular as a chain gripper system 21.Preferably, along the transport path provided for the transport of substrate 02, downstream of the alignment device 07, at least one drying device 23 is arranged, in particular for acting on the first side of the substrate 02. This drying device 23 is designed, for example, as a radiation dryer 23 and / or has, for example, at least one radiation source. For example, the printing press 01 has at least one cooling device, not shown, which is designed, for example, as a cooling roller. This cooling device is preferably arranged along the transport path provided for the transport of substrate 02 in or after the active area of the drying device 23. For example, the printing press 01 has at least one inspection device, not shown, which has, for example, at least one sensor device preferably designed as a camera, in particular a line camera. This inspection device is preferably arranged along the transport path provided for the transport of substrate 02 in or after the active area of the drying device 23.The alignment device 07 is preferably designed in the manner of a module and is inserted with interfaces on the input and output sides to the open section ends of a conveying system continuing upstream and downstream into the transport path of the printing press 01 provided for the transport of substrate 02.The alignment device 07 for forming optically variable image elements 03, e.g. for forming the optically variable effect into the optically variable coating agent 06 previously applied, e.g. in the form of printed image elements 08, to the substrate 02, in particular to the printing substrate 02, comprises a defined section of the transport path provided for the transport of substrate 02, along which the substrate 02 to be conveyed by the alignment device 07 is or can be brought into operative connection, preferably in such a way, from an inlet region, in which the substrate 02 to be treated and having optically variable coating agent 06 on its first side is or can be supplied, with an alignment device 26, which comprises elements 24 providing magnetic fields, short and magnetic elements 24, so that the magnetic elements 24 of the alignment device 26 serving for the image-forming alignment and the printing substrate 02 printed with the printing ink 06 containing the particles P move synchronously with one another at least over a section of the transport path provided for the transport of substrate 02. The alignment device 26 is preferably designed as a magnetically active cylinder 26, or magnetic cylinder 26 for short, which has the arrangement of magnetic elements 24 on the circumference and via which the printing material 02 is guided or conveyed from an inlet region in the direction of an outlet region of the alignment device 07. The printing press 01 therefore preferably has at least one alignment device 26 which is designed as a magnetic cylinder 26 having a plurality of magnetic elements 24.The magnet elements 24 can be formed directly by magnets themselves or preferably comprise one or more magnets 27, which is or are arranged in or on a holder, preferably in a detachable manner. Magnets 27 are understood here to mean, in general, magnetically active devices which permanently or switchably bring about a magnetic field-in particular sufficiently strong for aligning particles P contained in the coating agent 06 on the substrate 02 guided over it as described here-at least to the side of the transport path provided for the transport of substrate 02. The magnets 27 can be formed by one or more permanent magnets with or without engraving, by electromagnets or by combinations of one or more permanent and / or one or more electromagnets. Regardless of whether it is a single magnet or a combination of a plurality of magnets, for example permanent and / or electromagnets, the expression magnet 27 is also to be understood below as a plurality of magnets 27 assigned to the same magnetic element 24 and forming an active unit in their entirety, unless explicitly stated otherwise.In principle, two such alignment devices 26, in particular cylinders 26, can also be provided in the transport path provided for the transport of substrate 02, which are arranged on the same or on different sides of a transport path provided for the transport of substrate 02.In an advantageous embodiment, the alignment device 07 is assigned a drying and / or curing device 37, e.g. a radiation dryer 37, in particular UV radiation dryer 37, or UV dryer 37, which is preferably designed as UV LED dryer 37 and / or is directed at a point in the transport path provided for the transport of substrate 02, at which point the substrate 02 interacts with the alignment device.The alignment device 26, in particular the magnetic cylinder 26, is preferably arranged on that side of the transport path provided for the transport of substrate 02 which is remote from the at least one forme cylinder 14; 16. The first side of the substrate coated, in particular upstream in-line with optically variable coating agent 06, then preferably points outwards when it passes the alignment device 26, in particular when it is being transported via the magnetic cylinder 26.The alignment device 26 comprises, for example, a one- or preferably multi-part magnetic element carrier 29, on or on which the magnetic elements 24 are arranged, preferably in a detachable manner. For the preferred case of a cylinder 26 mounted as rotatable in a frame, the magnetic element carrier 29 is formed, for example, by a single- or preferably multi-part cylinder body 29. The term cylinder body 29 is intended to encompass both closed structures, i.e. with a more or less closed cylinder jacket surface, and open structures, i.e. framework-like or frame-like structures, such as the example presented for FIG. 4.The alignment device 26, which is preferably designed as a magnetic cylinder 26, preferably has the plurality of magnetic elements 24 in the region of the side facing the transport path provided for the transport of substrate 02, e.g. in the region of the outer periphery, in particular in the region of an outer cylindrical enveloping surface of the cylinder body 29, which serve for the orientation of at least a part of the magnetic or magnetizable particles P of the coating agent 06 applied to the passing printing substrate 02.In particular for the case of a plurality of blanks 09 per substrate section that is preferred and explained here, e.g. per printing substrate sheet or substrate sheet 02, a plurality of columns or groups are provided on the magnetic element carrier 29, for example on the cylinder body 29, as viewed in the axial direction, in particular a number of columns or groups corresponding to the number of columns on the printing substrate section 02, each having a plurality of magnetic elements 24 arranged one behind the other, in particular a number corresponding to the number of rows of blanks 09 on the printing substrate section 02 to be treated, as viewed in the transport direction T of the substrate 02 and / or as viewed in the circumferential direction of the cylinder 26. These magnetic elements 24 are preferably arranged in the manner of a matrix, preferably in such a way that the same number of magnetic elements 24 are provided on the circumference for each column or group and are arranged in rows running parallel to the axis, and / or in particular in such a way that, given a correct register between the substrate layer in the transport direction T and the cylinder angular position, they correspond to the pattern of the image elements 03 to be exposed to magnetic fields on the substrate 02 in a developed view on the substrate 02. Preferably, the magnet elements 24 of the groups arranged one behind the other are arranged one behind the other in the circumferential direction, in particular in such a way that they at least overlap one another in rolling along a circumferential line and / or come to lie in the blank 09 of the same column of a substrate 02 to be treated.Preferably, when guiding the substrate 02 over a magnetic cylinder 26 configured in such a way, wherein for example the first substrate side points outwards during transport over the first cylinder 26, an alignment or orientation of particles P in the region of the image elements 03 provided on the panel 09 can be effected by means of the magnetic elements 24, i.e. here e.g. through the substrate 02.For example, the number of groups or columns is four to eight, in particular five to seven, for example six. For example, the number of magnetic elements 24 of a column or group is, for example, between two and twelve, preferably between five and ten. The alignment device 26 or the magnetic element carrier 29 is preferably designed such that the number of groups and / or the number of magnetic elements 24 arranged one behind the other in a group can be varied-for example within the above-mentioned limits-in order to adapt them to requirements that differ from one another.Preferably, on the periphery of the cylinder 26, holding means 36, for example grippers 36 of a so-called gripper bar, are provided, by means of which a substrate sheet 02 to be conveyed over the cylinder 26 can be picked up with its leading end and can be held over an angular range during a rotation of the cylinder 26. A magnetic cylinder 26 configured in this way serves simultaneously for transporting the substrate 02.List of reference characters01 Printing press, sheet-fed printing press, screen printing press, security printing press 02 substrate, printing material, sheet, printing material sheet, substrate sheet 03 image element 04 printing unit, screen printing unit 05-06 coating agent, printing ink, varnish 07 alignment device 08 printed image element 09 blank, security paper, banknote 10-11 printing unit, screen printing unit 12 printing unit, screen printing unit 13 substrate source, sheet feeder 14 form cylinder, screen printing form cylinder, first 15-16 form cylinder, screen printing form cylinder, second 17 impression cylinder 18 printing element, print subject 19 conveying device, gripper circulation conveyor, chain gripper system 20-21 conveying device, gripper circulation conveyor, chain gripper system 22 substrate delivery device, stack delivery device, multiple stack delivery device 23 drying device, radiation dryer 24 element, Magnetic element 25 - 26 Alignment device, cylinder, magnetic cylinder 27 Magnet 28 Sheet contact device 29 Magnetic element carrier, cylinder body 30 - 31 Application point, first 32 Application point, second 33 Sheet transport means, suction drum 34 Transfer drum, receiving drum 35 - 36 Holding means, gripper 37 Drying and / or curing device, radiation dryer, UV radiation dryer, UV dryer, UV LED dryer 38 Gripper system, gripper bar 39 Delivery region 40 - 41 Sheet cleaning device 42 Discharge electrode 43 Brush bar, first 44 Brush bar, second 45 - 46 Suction opening 47 Front stop 48 Direct voltage source 49 Housing 50 - 51 Position adjustment device 52 Machine frame 53 Sheet separation device 54 Separation sucker 55 - 56 Transport sucker 57 Feeder stack 58 Transfer drum, 59 second zone of action A transverse direction P particles, pigment particles T transport direction

Claims

Sheet-fed printing press (01) having a sheet feeder (13) and at least one screen-printing unit (04), the screen-printing unit (04) having at least one first application point (31) which is formed by a impression cylinder (17) and a first screen-printing forme cylinder (14), characterized in that a sheet-contact device (28) of the sheet-fed printing press (01) has at least one sheet transport means (33) designed as a suction drum (33), and in that the sheet-fed printing press (01) has at least one first transfer drum (34) which is arranged after the suction drum (33) and before the impression cylinder (17) along a transport path provided for transporting sheets (02), and which has at least one gripper system (38), and in that the sheet-fed printing press (01) has at least one sheet-cleaning device (41), In the region of action (59) of which the transport path provided for the transport of sheets (02) is defined by the first transfer drum (34), and in that the sheet cleaning device (41) has, in succession along the transport path provided for the transport of sheets (02), at least one discharge electrode (42), a first brush strip (43), a suction opening (46) and a second brush strip (44).Sheet-fed printing press according to Claim 1, characterized in that the at least one discharge electrode (42) is arranged connected to at least one direct-current voltage source (48) for the purpose of supplying voltage.Sheet-fed printing press according to Claim 1 or 2, characterized in that the sheet-cleaning device (41) has a housing (49), relative to which the discharge electrode (42), the first brush strip (43) and the second brush strip (44) are arranged in a fixed position and which is arranged connected to a machine frame (52) of the sheet-fed printing press (01) via a position-setting device (51), and in that a distance between the discharge electrode (42) and the first transfer drum (34) can be set by means of the position-setting device (51).Sheet-fed printing press according to Claim 1 or 2 or 3, characterized in that the sheet-cleaning device (41) has a cavity (53) which extends over at least 80% of the working width of the sheet-fed printing press (01), and in that the suction opening (46) connects an outer region to the cavity (53), and in that the suction opening (46) extends over at least 80% of the working width of the sheet-fed printing press (01).Sheet-fed printing press according to Claim 1 or 2 or 3 or 4, characterized in that the sheet-fed printing press (01) has at least one alignment device (26) which is designed as a magnetic cylinder (26) having a plurality of magnetic elements (24).Sheet-fed printing press according to Claim 1 or 2 or 3 or 4 or 5, characterized in that the sheet-feed device (28) has at least one movable front stop (47) which is arranged such that it can be switched over between an alignment position interrupting the transport path provided for the transport of sheets (02) and a passing position releasing the transport path provided for the transport of sheets (02).Sheet-fed printing press according to Claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that the sheet-fed printing press (01) has a multiple-stack delivery (22) having a plurality of delivery regions (39).Sheet-fed printing press according to Claim 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized in that the screen printing unit (04) has the first application point (31) which is formed by the impression cylinder (17) and the first screen printing forme cylinder (14), and in that the screen printing unit (04) has a second application point (32) which is formed by the same impression cylinder (17) and a second screen printing forme cylinder (16).Sheet-fed printing press according to Claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that the sheet feeder (13) has a sheet-separating device (53) having at least one separating sucker (54) and at least one transport sucker (56).

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