PRINTING MACHINE WITH MULTIPLE SHEET-PROCESSING STATIONS

Description

[0001] The invention relates to a printing machine with a non-impact printing device according to claim 1.

[0002] The suction belt table described below is a machine unit for use in a machine arrangement for processing sheet-shaped substrates (referred to as sheets for short), such a machine arrangement comprising a plurality of machine units arranged one after the other in the transport direction of the sheets. At least two of these machine units each have the sheet-transporting transport devices. A suction belt table is used to transport processed sheets or sheets to be processed along a linear transport path in the respective machine arrangement, wherein these sheets are transported individually on at least one conveyor belt. Preferably, the individual sheets are held frictionally or force-fit on the respective conveyor belt while they are resting on the at least one conveyor belt by a suction force, i.e. by a holding force caused by a suction flow. The suction force is usuallyrealized by a vacuum acting on the respective sheet with reference to the surrounding barometric air pressure by means of a suction device.

[0003] In a preferred application, the suction belt table in a sheet-processing machine arrangement is arranged downstream of a dryer that dries the sheets in the sheet transport direction. In a further development, the dryer is initially followed by a cooling section for air-conditioning and / or conditioning the sheets heated in the dryer, so that the suction belt table is only arranged downstream of the cooling section. A machine arrangement of the aforementioned type, whether with or without a cooling section downstream of the dryer, has a plurality of processing stations arranged one behind the other in the sheet transport direction, each of which acts on the sheets, wherein each of these processing stations is designed, for example, as a machine unit in this sheet-processing machine arrangement.The suction belt table can - as mentioned - be arranged directly downstream of the dryer, so that no further processing station is located between the aforementioned dryer and the suction belt table, or it can be arranged downstream of the cooling section located downstream of the dryer. In the machine arrangement used here as the preferred embodiment, at least the transport device of the dryer upstream of the suction belt table or of the associated cooling section is designed as a transport device that transports the sheets horizontally along a linear transport path. The dryer is thus designed in particular as a continuous dryer for sheets in individual layers.

[0004] A further transport device, arranged downstream of the suction belt table in the transport direction of the sheets, is designed as a transport device that transports the sheets along a preferably curved, in particular circular-arc-shaped transport path. This further transport device is preferably arranged directly downstream of the suction belt table, i.e., no further processing station is arranged between the suction belt table and the downstream transport device in the respective machine arrangement. The sheets to be transported by this machine arrangement thus change from a linear transport path to a preferably curved, in particular circular-arc-shaped transport path after leaving the suction belt table.As can be seen below, changing from a linear transport path to a preferably curved, in particular circular, transport path on a suction belt table is sometimes very problematic.

[0005] From US 9,573,780 B2 a sheet transport arrangement for transporting a sheet along a process unit is known, which is configured to apply a process to the sheet, wherein the sheet transport arrangement comprises the following: a conveyor unit comprising a transport belt and a deflection element, wherein the transport belt is configured to advance the sheet in a transport direction along the process unit to the deflection element, wherein the sheet is placed with a contact side on the belt and with a process side towards the process unit, wherein the deflection element is arranged in contact with the transport belt in order to deflect the transport belt downstream in the transport direction relative to the process unit;a separation unit for separating the sheet from the conveyor belt, the separation unit being connected to an air supply source and comprising a holding blower device arranged in a holding region for directing a holding air flow to the process side of the sheet in order to drive the sheet towards the conveyor belt near the deflection element arranged to separate the sheet from the conveyor belt, and comprising a lifting blower device arranged in a lifting region for directing a lifting air flow to the contact side of the sheet for lifting the sheet from the conveyor belt, the lifting region being arranged to extend only over a central portion of a width of the sheet, the width being a dimension of the sheet in a lateral direction perpendicular to the transport direction;

[0006] US 2016 / 0152045 A1 discloses a sheet transport arrangement for transporting a sheet between two conveyors, which sheet transport arrangement comprises: a) a feeding conveyor having a conveyor belt, wherein the feeding conveyor is configured to transport the sheet in a transport direction along a process unit configured to apply a process to a process side of the sheet, to a transfer area for transferring the sheet to a receiving conveyor, wherein the sheet has a contact side in contact with the conveyor belt, b) a sheet blowing unit coupled to an air supply source, which sheet blowing unit has an air knife configured to direct an air flow to the process side of the sheet, wherein the process side is opposite the contact side, for pressing the sheet against a support element for supporting the sheet during its transport in the transfer area, wherein the sheet transport arrangement further comprises a control unit configured toto control the sheet blowing unit depending on at least one sheet attribute of the sheet, including a media characteristic of the sheet, wherein this media characteristic defines the wave deformation behavior of the sheet.

[0007] From US 2020 / 0017310 A1 a printing press is known, comprising a first conveyor belt and a downstream, second conveyor belt for transporting sheets and a guide element for the sheets in between, wherein a blowing device is provided for lifting a leading edge of the respective sheet in the region of the transition from the first conveyor belt to the guide element, wherein the blowing device is preferably arranged in front of the guide element as seen in the transport direction of the sheets.

[0008] A sheet processing machine is known from DE 10 2017 212 984 A1, wherein at least one protrusion sensor for detecting at least one spatial extent of sheets is arranged along a transport path provided for transporting sheets, and wherein at least one compression device is arranged, which has at least one first compression body and at least one second compression body and at least one force element, and wherein the at least one first compression body is arranged to be movable by means of the at least one force element from a through position towards the at least one second compression body into a compression position, and wherein, when the first compression element is arranged in the through position, the at least one force element is pretensioned, and wherein the at least one compression device has at least one retaining device,which is switchable at least between a retention state and a release state and which, in the retention state, is arranged to prevent movement of the at least one first compression body from its passage position into its compression position.

[0009] Through US 2018 / 0072076 A1 a digital printing machine is known, comprising a first sheet conveyor belt made of a first material, a second sheet conveyor belt made of a second material, a print head for printing the front and back of a printed sheet, the print head being directed towards the first sheet conveyor belt, a turning device for turning the printed sheet between printing the front and printing the back, and a dryer for drying an imprint printed on the printed sheet with the print head, the dryer being directed towards the second sheet conveyor belt.

[0010] DE 10 2016 207 397 A1 discloses a sheet processing machine arrangement with a suction belt table arranged after a dryer that dries the sheets.

[0011] US 2009 / 0190981 A1 discloses a device having a blower unit for separating moving sheets from a conveyor belt transporting the sheets, wherein the blower unit blows air in its central section substantially counter to and perpendicular to the direction of movement of the sheets and in a side section blows air substantially counter to and sideways to the direction of movement of the sheets.

[0012] The invention is based on the object of creating a printing machine with a non-impact printing device.

[0013] The object is achieved according to the invention by the features of claim 1. The dependent claims each show advantageous embodiments and / or further developments of the solution found.

[0014] The advantages achieved with the invention consist, in particular, in enabling trouble-free sheet transfer between its processing stations in the printing press. Further advantages will become apparent from the following description.

[0015] Embodiments of the invention are described in more detail below, if necessary with the aid of the drawings.

[0016] They show: Fig. 1a suction belt table in a sheet processing machine arrangement; Fig. 2a side view of the suction belt table according to Fig. 1 ; Fig. 3 a top view of the Fig. 2 shown suction belt table; Fig. 4 a side view of a catching device integrated into the suction belt table; Fig. 5 the catching device of the Fig. 4 in its parking position; Fig. 6 the safety device of the Fig. 4 in its catching position; Fig. 7 a section of the Fig. 2 with the catching device in its catching position; Fig. 8 a pneumatic circuit for the operation of the catching device; Fig. 9 a diagram for the stroke of the cylinder piston of a pneumatic cylinder driving the catching device; Fig. 10 a diagram for the speed of the cylinder piston during operation of the catching device; Fig. 11 a diagram for the acceleration of the cylinder piston during operation of the catching device; Fig. 12 a diagram for the course of the piston force of the cylinder piston during operation of the catching device; Fig. 13 a schematic representation of a circuit for removing a frictional connection or force connection of sheets held on the suction belt table; Fig. 14 a section of the Fig. 3 a suction belt table shown in a plan view; Fig. 15 a guide device between two conveyor belts arranged one after the other in the transport direction of the sheets; Fig. 16 an initial situation for the function of the guide device; Fig. 17 the guide device at the beginning of its activation; Fig. 18 the activated guide device; Fig. 19 the guide device when taking over a sheet; Fig. 20 a section of the Fig. 3 shown top view of the suction belt table with a nozzle arrangement; Fig. 21 a section of the Fig. 2 shown side view of the suction belt table.

[0017] An example of the machine arrangement mentioned above can be found in the Fig. 1 shown. Such a machine arrangement is known, for example, from the aforementioned DE 10 2016 207 397 A1. The sheet-processing machine arrangement chosen as an example initially has, as seen in the transport direction T of the sheets, a sheet feeder 01 in which a first stack 02 of sheets is ready for processing. The sheets are preferably rectangular substrates made of paper, cardboard or paperboard. Paper, cardboard and paperboard differ in their respective basis weight, known as grammage, i.e. the weight in grams for one square meter of these sheets. Paper has a basis weight of between 30 g / m 2< and 150 g / m 2< , cardboard a basis weight of between 150 g / m 2< and 600 g / m 2< and paperboard a basis weight of more than 600 g / m 2< . However, the sheets can also each have a substrate made of a plastic and / or be in the form of a thin panel. The sheet feeder 01 can also be designed as a magazine feeder having several first stacks 02.

[0018] A suction head 03 grips each of the stacked sheets one after the other from above and feeds these sheets, e.g. by means of a first oscillating gripper 04 and optionally a transfer drum 34 interacting with the first oscillating gripper 04, in a sequence of separated sheets, e.g. to a first coating device 05, wherein this first coating device 05 is designed, e.g., as a primer application device. The first coating device 05 has a transport cylinder 06, e.g. designed as a printing cylinder, and e.g. a printing unit cylinder 07 interacting with this transport cylinder 06 and having an applicator roller 08, preferably in the form of an anilox roller, positioned or at least positionable against this printing unit cylinder 07. At least one doctor blade 09 or a chambered doctor blade system 09 extends in the axial direction of the applicator roller 08 for optimal metering of a coating material to be applied to the surface of the sheets.The transport cylinder 06 transports the sheets held on its outer surface along a curved, in particular circular-arc-shaped transport path. The first coating device 05 applies the coating material, e.g. a primer, to one of the two sides of the sheets, either over the entire surface or only at specific, i.e., predetermined locations, i.e., partially. The sheets are then picked up by the transport cylinder 06 of the first coating device 05, e.g., by means of a first gripper system 11, in particular a first chain conveyor, and e.g.at least one first conveyor belt 12 to a non-impact printing device 13, wherein the first gripper system 11 and the first conveyor belt 12 cooperate in transferring the sheets to the non-impact printing device 13, in such a way that the first gripper system 11 delivers the sheets to the first conveyor belt 12 having a linear transport path, wherein a transfer of the sheets to the non-impact printing device 13 takes place from the first conveyor belt 12.

[0019] The first conveyor belt 12 is preferably designed as a continuous, continuous belt. In an advantageous embodiment, a first dryer 14 is provided in the area of ​​the first gripper system 11. This dryer 14 dries the sheets coated in the first coating device 05. This dryer 14 is designed, for example, as a hot-air dryer and / or as a dryer drying by IR radiation or UV radiation.

[0020] The non-impact printing device 13 generally has at least four independently controllable inkjet printing devices, each of which applies a different printing ink to the side of the sheet previously coated, for example, in the first coating device 05, to create a preferably multi-colored print image. In the machine arrangement described here as an example, the non-impact printing device 13 has a second conveyor belt 16, so that the sheets are printed by the inkjet printing devices while they are resting on this second conveyor belt 16. The second conveyor belt 16 is designed as a circulating endless belt. However, it is also possible to provide a plurality of conveyor belts 16, for example on two conveyor belts 16 arranged parallel to one another in the transport direction T of the sheets.In the sheet transport direction T, a second dryer 17 for drying the printed sheets is arranged downstream of the non-impact printing device 13. This second dryer 17 is also designed, for example, as a hot-air dryer and / or as a dryer that dries using IR radiation or UV radiation. The second dryer 17 has a transport device 18 that transports the sheets horizontally in a translational manner, i.e., along a linear transport path. This transport device 18 is arranged in the manner shown in FIG. Fig. 1 The third conveyor belt 18 is also designed as a circulating endless belt. The conveyor device 18 of the second dryer 17 in this example transfers the dried sheets to a suction belt table 19, from which the sheets are transferred to a second coating device 22, for example by means of a second oscillating gripper 21 and optionally a transfer drum 33 cooperating with the second oscillating gripper 21. The second coating device 22 is designed, for example, as a varnishing device, wherein this second coating device 22 applies a coating material, for example, a varnish, in particular to a print image previously created in the non-impact printing device 13. The second coating device 22 has, as a transport device for sheets to be transported, a

[0021] Transport cylinder 23, wherein with this transport cylinder 23, for example, a printing unit cylinder 24 cooperates with an application roller 26, preferably in the form of an anilox roller, which is positioned or at least positionable on this printing unit cylinder 24, wherein at least one doctor blade 27 or a chamber doctor blade system 27 extends in the axial direction of the application roller 26.

[0022] The sheets are then transported by the transport cylinder 23 of the second coating device 22, for example, by means of a second gripper system 28, in particular a second chain conveyor, to a delivery 29, wherein the sheets processed in this exemplary machine arrangement are deposited by the second gripper system 28 in the delivery, preferably in a second stack 32. In an advantageous embodiment, a third dryer 31 is provided in the region of the second gripper system 28, which dries the sheets coated in the second coating device 22, wherein this third dryer 31 is designed, for example, as a hot air dryer and / or as a dryer drying by IR radiation or UV radiation. The delivery 29 can also be designed as a multi-stack delivery having a plurality of second stacks 32. The Fig. 1 The machine arrangement shown as an example is designed as a digital printing machine for use in an industrial printing process, in particular for the production of printed products in mass production.

[0023] Fig. 2 shows a side view of the suction belt table 19, as it is used, for example, in a machine arrangement according to the Fig. 1 The transport direction T of the sheets is in the Fig. 2 from right to left. 19 individual sheets are fed sequentially to the suction belt table from a Fig. 2 only partially shown transport device 18 at a transport speed of several thousand sheets per hour, e.g. of approximately 10,000 sheets per hour. In this case, adjacent sheets in their transport direction T, i.e., directly following one another in the sequence, are each spaced apart from one another by a gap. This gap is significantly smaller than a length of the sheets extending in the transport direction T of the sheets and amounts to only a few millimeters, e.g. approximately 20 mm. In the preferred embodiment here, the transport device 18 arranged upstream of the suction belt table 19 in the transport direction T of the sheets belongs to a dryer 17, said dryer 17 being arranged according to the Fig. 1 The machine arrangement shown by way of example comprises a second dryer 17, wherein the sheets are transported by this transport device 18 lying on a conveyor belt, each in a translational manner, i.e., along a linear transport path. The suction belt table 19 initially receives each individual sheet in a conveying plane defined by the transport device 18 arranged upstream of this suction belt table 19 and theoretically extended in the transport direction T of the sheets, wherein this conveying plane is preferably aligned horizontally. In the further course of the transport path of the sheets, the conveying plane E19 ( Fig. 4 ) of the suction belt table 19 with respect to the horizontal conveying plane of the transport device 18 arranged upstream of this suction belt table 19 has a downward inclination with an acute angle in the range between 5° and 30°, preferably in the range between 15° and 25°. At the end of the transport path determined by the suction belt table 19, each sheet strikes with its leading edge in the transport direction T against front lays 36 of the oscillating gripper 21 arranged downstream of the suction belt table 19, this oscillating gripper 21 being in the Fig. 1 The machine arrangement shown by way of example is a second oscillating gripper 21. From this oscillating gripper 21, each sheet is transferred individually to a transfer drum 33 cooperating with this oscillating gripper 21. The sheets are completely braked at the front lays and aligned in register.

[0024] In its preferred embodiment, the suction belt table 19 has an shingling device for sheets to be transported. Above the conveying plane E19 of the suction belt table 19, the shingling device has a box-shaped housing, the so-called blow box 37, which preferably extends over the entire width of the sheets, i.e. transversely to the transport direction T of the sheets, wherein in the blow box 37, on the side thereof facing the conveying plane E19 of the suction belt table 19, a plurality of blow nozzles are arranged one behind the other in the transport direction T of the sheets. In the preferred embodiment, at least two rows of a plurality of blow nozzles arranged next to one another are arranged one behind the other in the transport direction T of the sheets and in each case transversely to the transport direction T of the sheets. A respective blowing direction of the blow nozzles is directed essentially parallel to the conveying plane E19 of the suction belt table 19, opposite the transport direction T of the sheets.The respective blowing direction of the blowing nozzles is determined, for example, by at least one guide surface that channels the flow of the blowing air and is arranged and / or molded onto the respective blowing nozzle. The respective guide surface is formed on the side of the blow box 37 facing the conveying plane E19 of the suction belt table 19, for example, as a ramp protruding from this blow box 37. The blowing air flowing out of the respective blowing nozzles is preferably controlled, for example, in terms of time and / or intensity, by adjustable pneumatic valves, wherein the valves are controlled, for example, by a preferably digital control unit 71 that executes a program. The valves are switched, for example, by the control unit 71, in particular in a cycle, wherein a cycle duration and / or a cycle frequency is preferably set as a function of the advance of the sheets fed to the suction belt table 19.Valves controlled in a cycle by a preferably digital control unit 71 are also referred to as cycle valves.

[0025] In the transport direction T of the sheets, a partition plate 38 is arranged in an area between the conveying plane E19 of the suction belt table 19 and the side of the blow box 37 facing this conveying plane E19 in front of the first blow nozzle or the first row of blow nozzles, wherein the partition plate 38 shields the front edge of a subsequent sheet, ie a sheet which directly follows a sheet lifted by the blow air from at least one of the blow nozzles of the blow box 37, against the suction effect caused by the blow nozzles arranged in the blow box 37. The arch raised by at least one of the blow nozzles or rows of blow nozzles of the blow box 37 from the conveying plane E19 of the suction belt table 19 channels the blow air flowing out of the at least one blow nozzle of the blow box 37 and directs this blow air over the surface of the partition plate 38 facing the blow box 37.The partition plate 38 preferably has a concave curvature at its end located in the blowing direction, this curvature giving the blown air an outflow direction facing away from the conveying plane E19 of the suction belt table 19, i.e. directed away. Due to the partition plate 38, the leading edge of a sheet which directly follows a sheet lifted by the blown air from at least one of the blowing nozzles remains unaffected until the lifted sheet, through its own progress in movement or feed in the transport direction T, exposes with its rear end the blowing nozzle or row of blowing nozzles which this sheet first reaches in its transport direction T. In order to prevent the leading edge of the sheet which directly follows a sheet lifted by the blown air from at least one of the blowing nozzles from being prematurely exposed due to the effect of the blowing nozzle or row of blowing nozzles exposed by the rear end of the preceding sheet.blowing nozzle row is raised, the blowing air of the blowing nozzle or blowing nozzle row in question is switched off by means of the respective associated valve depending on the movement progress or feed of the sheet currently raised from the conveying plane E19 of the suction belt table 19 and directly preceding a sheet located between the partition plate 38 and the conveying plane E19 of the suction belt table 19.

[0026] A sheet lifted by the blowing nozzles or rows of blowing nozzles is lifted above the conveying plane E19 of the suction belt table 19 to a specific floating height, which is determined, for example, by a distance from the side of the blowing box 37 facing the conveying plane E19 of the suction belt table 19, due to the suction effect (Venturi effect), whereby this floating height depends on the intensity of the respective blowing air and / or on the mass of the sheet in question and / or on the transport speed of the sheet in question. B. large mass and / or high transport speed during their transport in the conveying plane E19 of the suction belt table 19 start to vibrate and flutter, in the area between the conveying plane E19 of the suction belt table 19 and the side of the blow box 37 facing this conveying plane E19, a support plate supporting the raised sheet is preferably provided, wherein e.g.at an acute angle to the side of the blow box 37 facing the conveying plane E19 of the suction belt table 19, is designed, for example, in the form of an air-permeable grid. The sheet, lifted by the suction of the blow air and placed against the support plate, is guided there in a smooth movement, i.e. without fluttering, in its transport direction T along this support plate. In the conveying plane E19 of the suction belt table 19, at least in one area opposite the blow box 37, preferably a plurality of openings 39 (. Fig. 3 ) through which air flows beneath the currently raised sheet to equalize the pressure. These openings 39 are, for example, circular with a diameter in the range of a few millimeters. In addition, a plurality of suction chambers 41, each of which can be controlled in terms of its fluidic effect, are arranged below the conveying plane E19 of the suction belt table 19. These suction chambers 41 are preferably arranged one behind the other in the transport direction T of the sheets and their respective pressure can be switched, for example, individually and independently of one another, by means of a suction device controlled by the control unit 71.

[0027] Fig. 3 shows in a top view the Fig. 2 shown suction belt table 19. The transport direction T of the sheets is as shown in the Fig. 2 from right to left. Thus, individual sheets are fed sequentially to the suction belt table 19 by a transport device that transports the sheets in a translatory manner, in particular by a transport device belonging to a dryer 17. The sheets each rest on at least one transport belt 18, preferably on several, e.g. on two transport belts 18 arranged parallel to one another in the transport direction T of the sheets. These transport belts 18 are each designed, for example, as endlessly circulating flat belts or flat belts. At the transition from the transport device upstream of the suction belt table 19 to this suction belt table 19, a guide device 42 extending transversely to the transport direction T of the sheets is arranged, preferably with several lifter nozzles 43 arranged in at least one row. In the transport direction T of the sheets, there is then at least one transfer belt 44, which e.g.as a circulating flat belt arranged in the central region of the conveying plane E19 of the suction belt table 19 and also preferably as a suction belt, the suction belt having a perforation at least in sections. In the transport direction T of the sheets, after the transfer belt 44 or in its effective area in the conveying plane E19 of the suction belt table 19 there follows at least one bend 46, preferably several successive bends 46; 47 for a step-by-step curvature of the previously, for example, horizontal conveying plane, wherein at each of these bends 46; 47 the conveying plane E19 of the suction belt table 19 experiences, compared to the previous orientation of the conveying plane, a possibly further downward inclination with an acute angle in the range between 5° and 30°. Fig. 2 and 3In the example shown, two successive bends 46; 47 are shown, the first bend 46 being arranged in the effective area of ​​the transfer belt 44 and the second bend 47 being arranged at a short distance of less than one sheet length in the transport direction T of the sheets after the transfer belt 44. In the conveying plane E19 of the suction belt table 19, for example symmetrically to its center line M, spanning the distance between the bends 46; 47, there are preferably two jump belts 48 arranged parallel to one another in the transport direction T of the sheets, for example in the form of endless belts each circulating, preferably each designed as a suction belt.The skid belts 48 are pivotally mounted at their rear end in the transport direction T of the sheets, which end is thus reached first by a sheet brought forward in particular by the transfer belt 44, so that these skid belts 48 can be pivoted out diagonally upwards at an acute angle opening in the transport direction T of the sheets from the previous conveying plane E19 of the suction belt table 19 and, in their extended operating state, form a raised ramp for the sheets to be transported. In the . Fig. 2 The skid belts 48 are shown in their normal operating state, i.e., not pivoted out, preferably flush with the remaining conveying plane E19 of the suction belt table 19. In a preferred embodiment, a plurality of nozzles 49, preferably each designed as Venturi nozzles, are arranged at least in the respective longitudinal edge regions of the region of the conveying plane E19 of the suction belt table 19 spanned by the skid belts 48. This arrangement of the Venturi nozzles begins in the transport direction T of the sheets at a distance of, for example, less than 200 mm, preferably less than 100 mm behind the at least one lifter nozzle 43.

[0028] Above the conveying plane E19 of the suction belt table 19, a catching blower 51 extending transversely to the transport direction T of the sheets is arranged at a distance A51 ( Fig. 2 and 3), wherein this catching blower 51 has a plurality of blowing nozzles arranged in a row extending across the entire width B19 of the conveying plane E19 of the suction belt table 19. Below the catching blower 51, in the conveying plane E19 of the suction belt table 19, particularly in its central region, begins a switching area 52 extending in the transport direction T of the sheets and having a plurality of suction bores 53.The suction holes 53 in the switching area 52 form and open up a fluidic connection to at least one of the preferably several suction chambers 41 each arranged below the conveying plane E19 of the suction belt table 19, wherein these suction chambers 41 are switched or at least switchable in their respective pressure by the control unit 71, in particular individually and independently of one another, so that in this switching area 52, by means of the suction holes 53 and by the respective adjustment of the pressure in the respective suction chamber 41 in the conveying plane E19 of the suction belt table 19, a negative pressure can be set or at least adjusted. The suction holes 53 arranged in the switching area 52 are arranged, for example, symmetrically to the center line M of the conveying plane E19 of the suction belt table 19 in several rows, for example, in two rows, and are each designed, for example, as a suction cup utilizing the Bernoulli effect. In the transport direction T of the sheet, the switching area 52 is adjoined, for example, byin a manner overlapping with the switching area 52, at least one feed belt 54, in particular designed as a suction belt, wherein the suction belt has a perforation at least in sections, wherein the at least one feed belt 54 extends in the transport direction T of the sheets preferably to below the blow box 37 of the under-shingling device. The at least one feed belt 54 is preferably designed as a circulating endless belt. In a preferred embodiment, several, e.g. two, feed belts 54 are provided, for example symmetrical to the center line M of the conveying plane E19 of the suction belt table 19. The area which extends in the conveying plane E19 of the suction belt table 19 opposite the blow box 37 and in which preferably several openings 39 (. Fig. 3 ) are provided, through which air flows under a sheet currently lifted by the shingling device for pressure compensation, the sheet extends at least partially longitudinally to the at least one feed belt 54 on the edge side in the conveying plane E19 of the suction belt table 19 in the transport direction T.

[0029] In the transport direction T of the sheets, after the at least one feed belt 54 and / or after the shingling device in the conveying plane E19 of the suction belt table 19, there follow braking belts 56, which are arranged, for example, symmetrically to their center line M and are preferably each designed as a circulating endless belt, which have the function of reducing the respective transport speed of approaching sheets before they are transferred to a transport device arranged immediately downstream of the suction belt table 19, for example to an oscillating gripper 21.The sheets, preferably with their respective transport speed reduced, are then gripped as they continue to move in the transport direction T by a rotating or at least rotatable suction roller 57, which is subjected to negative pressure by a suction device. This suction roller 57 extends transversely to the transport direction T of the sheets, preferably at least over the entire width of the sheets or over the entire width B19 of the suction belt table 19. Thereafter, each of the sheets, held one after the other by the suction roller 57, reaches the front lays 36 of the oscillating gripper 21 arranged directly downstream of the suction belt table 19 with its leading edge in the transport direction T, i.e., its front edge, for example.Through the interaction of the shingling device, the brake belts 56, the suction roller 57 and the front lays 36 of the oscillating gripper 21, the sheets, which were previously transported individually, one behind the other, with a gap between them, are transferred into an shingled stream before these sheets are transferred to a transport device immediately downstream of the suction belt table 19, e.g. to an oscillating gripper 21, in order to then be transported in a rotary manner in a machine arrangement designed as a digital printing machine and having this suction belt table 19 to a coating device 22, e.g. to a coating device 22 designed as a varnishing device, and through this.

[0030] During operation of such a machine arrangement, possibly in the industrial printing process of a digital printing press, a malfunction can occur from time to time for various reasons in a processing station downstream of the suction belt table 19, e.g. designed as a coating device 22. A serious malfunction in such a processing station results in the transfer of sheets to the transport device downstream of the suction belt table 19 having to be abruptly interrupted. This operating situation creates a stoppage. In the event of a stoppage, sheets in transport in the machine arrangement must be collected and stacked very quickly and effectively. In a machine arrangement forming a digital printing press, however, it is not possible, due to the design conditions, in particular due to a lack of the necessary space in terms of height, to have a processing station upstream of the suction belt table 19, e.g.to collect and stack a large number of sheets which are transported in rapid succession, i.e. closely spaced one behind the other, at high transport speeds, in a first coating device 05 or in the non-impact printing device 13 or in a dryer 17 downstream of the non-impact printing device 13. In this case, it is not a satisfactory solution to arrange an ejection device downstream of the dryer 17 downstream of the non-impact printing device 13 and upstream of the suction belt table 19 in the transport direction T of the sheets. In the event of a stop, this ejection device directs all sheets still being fed out of the dryer 17 downstream of the non-impact printing device 13 under the suction belt table 19 and deposits them there. This is because the depositing of the sheets there is only possible in a more or less orderly manner. This solution also has the disadvantage that sheets collected under the suction belt table 19 can only be removed again under very unfavorable ergonomic conditions.Furthermore, there is hardly any possibility of arranging the conveyor elements required for the smooth, trouble-free transfer of the stream of individual sheets from the dryer 17 in the area of ​​the discharge device. Without such suitable conveyor elements, however, there may be a loss of the holding force with which the sheets, which are usually considerably warped due to the heat input during drying, are held. This would result in a disruption in the transport of the sheets. The task therefore arises of catching and stacking the sheets on the suction belt table 19 before they are transferred to the transport device downstream of the suction belt table 19. It should be noted, however, that it is not possible to carry out continuous shingling to form a stack on the under-shingling device of the suction belt table 19.This is because the nozzles which act from above to create shingles by sucking on the trailing edge of the sheet in question are ineffective at the latest when the sheets immediately follow, because the preceding sheet is not removed when the sheets are collected and thus shields the suction effect on the next sheet below.

[0031] A suction belt table 19 with a catching device 58 is therefore proposed, with which catching device 58 individual sheets following one another in a sequence are caught and stacked on the suction belt table 19 before they are transferred to a transport device downstream of the suction belt table 19. In the preferred embodiment, this suction belt table 19, which preferably has an under-shingling device, is arranged in the transport direction T of the sheets downstream of a dryer 17 downstream of a non-impact printing device 13. In a particularly preferred embodiment, the suction belt table 19 is arranged in a machine arrangement at a point at which the sheets are transferred from a linear transport path immediately upstream of this suction belt table 19 to a curved, in particular circular, transport path immediately downstream of this suction belt table 19.

[0032] The proposed catching device 58 comprises a slider-crank mechanism, the coupling of which has at least one stop surface 66 for the sheets to be caught. Details of the catching device 58 and its operation are explained below with reference to the Fig. 4 bis 6 described.

[0033] Fig. 4 shows an example of a side view of the catching device 58. This catching device 58 is arranged, as long as it is inactive, i.e. not actuated by the control unit 71, below the conveying plane E19 of the suction belt table 19, preferably approximately one sheet length extending in the transport direction T of the sheets from a line drawn by the catching blower 51 perpendicular to the conveying plane E19 of the suction belt table 19 corresponding to the distance A51 at the end of the switching area 52 of this suction belt table 19 having suction holes 53. The catching device 58 has a drive 59, which is preferably designed as a double-acting pneumatic cylinder 81, the cylinder piston 82 of which can be pressurized with compressed air on both sides ( Fig. 8 ). A bidirectionally linearly movable piston rod 61 of the pneumatic cylinder 81 is connected to a crank 62 designed as an angle lever, forming a pivot point G61, wherein the crank 62 is rotatably mounted at a pivot point D62 fixedly arranged in the suction belt table 19. The crank 62 designed as an angle lever has a short lever and a lever that is longer than this short lever, wherein the short lever connects the pivot point G61, at which the piston rod 61 of the pneumatic cylinder 81 is connected to the crank 62, with the pivot point D62 of the crank 62. The crank 62 is in turn connected to a coupling 63, forming a pivot point G62. The longer lever of the crank 62 extends between its pivot point D62 and the pivot point G62, at which the crank 62 is connected to the coupling 63.The coupling 63 and the crank 62 driving the coupling 63 interact to form a slider-crank mechanism, wherein an end point E2 of the coupling 63 facing away from the drive 59 of the catching device 58 is bidirectionally linearly movable along a path 64 arranged parallel to the conveying plane E19 of the suction belt table 19. The end point E2 of the coupling 63 facing away from the drive 59 of the catching device 58 and the pivot point D62 of the crank 62 thus lie on a straight line G64 connecting them, wherein this straight line G64 runs parallel to the conveying plane E19 of the suction belt table 19.

[0034] The coupling 63 has at least one stop surface 66 for sheets to be caught in an area between its end point E1 facing the drive 59 of the catching device 58 and the pivot point G62, at which the crank 62 is connected to the coupling 63. The stop surface 66 in question is thus preferably a component of the coupling 63. The stop surface 66 in question is preferably made of a plastic, e.g., a polyamide (abbreviation PA) or a thermoplastic such as polyoxymethylene (abbreviation POM).

[0035] In a preferred embodiment, the slider-crank mechanism has a centric slider crank, which means that the three Fig. 4 The illustrated sections G62-D62, G62-E2, and G62-E1 are each of equal length, and the end points E1; E2 of the coupling 63, including the articulation point G62 arranged therebetween, all lie on a straight line G63 connecting the end points E1; E2 of the coupling 63. The length ratio of the short lever and the longer lever of the crank 62 to one another is such that they translate a movement triggered by the drive 59 of the arresting device 58 and acting on the coupling 63 into a faster speed. The transmission ratio i into a faster speed is preferably at least 1:5 (i = 0.2).

[0036] In connection with the Fig. 5 bis 7 The functionality of the arresting device 58 is shown. Fig. 2 and 5show the catching device 58 in its inactive, ie unactuated starting position or parked position, in which the at least one stop surface 66 formed on the coupling 63 is arranged below the conveying plane E19 of the suction belt table 19. Thus, the sheets can pass the suction belt table 19 in its conveying plane E19 unhindered, which in the Fig. 5 indicated by two consecutive directional arrows. As can be seen from the Fig. 5 As can be seen, the piston rod 61 of the pneumatic cylinder 81 forming the drive 59 of the catching device 58 is extended by a corresponding application of compressed air to this pneumatic cylinder 81 and the end point E2 of the coupling 63 facing away from the drive 59 of the catching device 58 takes up its position on the track 64 furthest from the drive 59 of the catching device 58.

[0037] The Fig. 6 and 7show the arresting device 58 in its arresting position. In the arresting position, the at least one stop surface 66, preferably formed on the coupling 63, penetrates through a corresponding, e.g. slot-shaped opening 67 ( Fig. 3 ) the conveying plane E19 of the suction belt table 19 and, by means of a pivoting movement, sets itself up from a position previously inclined at a preferably acute angle to the conveying plane E19 of the suction belt table 19, preferably perpendicular to this conveying plane E19 ( Fig. 6 and 7 ), so that sheets transported on the suction belt table 19 hit at least one stop surface 66, which protrudes approximately 50 mm from the conveying plane E19 of the suction belt table 19 (see direction arrows in the Fig. 6 ) and are thus caught and prevented from making any further progress in the transport direction T. Sheets which are transported one after the other and each hit the raised stop surface 66 are placed on top of one another in the transport direction T of these sheets in front of the raised stop surface 66 and are thus stacked. In the catching position, the piston rod 61 of the pneumatic cylinder 81 forming the drive 59 of the catching device 58 is retracted by a corresponding application of compressed air to this pneumatic cylinder 81 and the end point E2 of the coupling 63 facing away from the drive 59 of the catching device 58 assumes its position on the path 64 closest to the drive 59 of the catching device 58.

[0038] Fig. 7 shows an excerpt from the Fig. 2 with skid belts 48, which are shown in their operating state in which they protrude diagonally upwards from the previous conveying level E19 of the suction belt table 19 at an acute angle opening in the transport direction T of the sheets, as well as with a catch blower 51, activated for example by the control unit 71, the activation of which in the Fig. 7 is indicated by a blowing direction arrow directed towards the conveying plane E19 of the suction belt table 19.

[0039] If the operating situation constituting a stop occurs in which a serious malfunction occurs in a processing station of the machine arrangement comprising the suction belt table 19, e.g., designed as a coating device 22, with the consequence that the transfer of sheets to the transport device downstream of the suction belt table 19 must be abruptly interrupted, then the catching device 58 is switched to its catching position by the drive 59 of the catching device 58 being actuated automatically, in particular program-controlled, by a control unit 71, usually by the further control unit 71, which preferably controls all functions of the suction belt table 19. This control unit 71 also controls, for example, the valves of the blow box 37 ( Fig. 2 ). Simultaneously with the actuation of the catching device 58, the transport speed of the sheets can be reduced, for example, by transport devices arranged upstream of the catching device 58 in the transport direction T of the sheets reducing their respective transport speeds. Even if the transport speed of a transport device arranged upstream of the catching device 58 in the transport direction T of the sheets is not reduced immediately upon actuation of the catching device 58, e.g.the transport speed of the skid belts 48 and / or the feed belt 54, the negative pressure set in the relevant suction chamber 41 by means of a suction device 72 controlled by the control unit 71 is switched off in each case. This suction chamber 41 is fluidly connected to the relevant switching area 52 by means of the suction bores 53 formed in the conveying plane E19 of the suction belt table 19 and at least partially overlaps with a floor plan of the stack of sheets to be caught. The at least one stop surface 66 of the catching device 58 is then inserted into a sheet gap between the trailing edge of a preceding sheet and a leading edge of a first subsequent sheet to be caught.For this purpose, the control unit 71 actuates at least one pneumatic switching valve 86, preferably two pneumatic switching valves 86; 87 simultaneously, so that the piston rod 61 of the pneumatic cylinder 81 forming the drive 59 of the catching device 58 is retracted.

[0040] In an advantageous embodiment, this pneumatic cylinder 81 has a bottom chamber 68 and a bearing chamber 69 separated from the bottom chamber 68 by a cylinder piston 82 rigidly connected to the piston rod 61, wherein a first pneumatic switching valve 86 is connected to the bottom chamber 68 and a second pneumatic switching valve 87 is connected to the bearing chamber 69. These two switching valves 86; 87 are each controlled by the control unit 71 of the catching device 58. In a first embodiment, the bottom chamber 68 can have barometric pressure. In another second embodiment, the bottom chamber 68 can have a differential pressure greater than the barometric pressure and less than the pressure in the bearing chamber 69. In a preferred embodiment, the piston rod 61 of the pneumatic cylinder 81 forming the drive 59 of the catching device 58 is retracted by pressurizing the bearing chamber 69, e.g., with 7 bar.During this retraction of the piston rod 61 of the pneumatic cylinder 81, the cylinder piston 82 of the pneumatic cylinder works against compressed air pre-pressurized in the base chamber 68, for example, with 2 bar, which can escape in a throttled manner via the open pneumatic switching valve 86 of the base chamber 68 and, if necessary, via a subsequent throttle valve 91. The braking effect of this counterpressure only sets in relatively late, so that the movement of the cylinder piston 82 and thus also of the piston rod 61 initially experiences a very large acceleration with resulting speed, before the movement of the cylinder piston 82 is braked at its end by the actively clamped air column and the residual speed is braked by an end-position damping element 83; 84 of the pneumatic cylinder 81.This very fast movement of the cylinder piston 82 is strongly translated by the crank 62 to the coupling 63 arranged in a central slider crank position, preferably with a transmission ratio i to the faster speed of at least 1:5 (i = 0.2).

[0041] With the proposed slider-crank mechanism, it is possible to bring at least one stop surface 66 of the catching device 58 into the catching position even at a high sheet transport speed of several thousand sheets per hour, e.g., approximately 10,000 sheets per hour, through a sheet gap measuring only approximately 20 mm, for example. The reaction time achievable with the proposed slider-crank mechanism thus significantly exceeds the switching times of simple folding and / or sliding mechanisms which are driven, for example, by switching magnets or directly, i.e., gearlessly, by a pneumatic cylinder 81. A further advantage of the solution found is that the proposed slider-crank mechanism is comparatively simple and space-saving.

[0042] This results in a machine arrangement with a plurality of processing stations, each processing sheets, wherein these processing stations are arranged one behind the other in the transport direction T of the sheets, wherein at least one of these processing stations has a transport device 18 which transports the sheets lying down along a linear transport path, wherein this transport device 18 is designed to transport individual sheets which follow one another directly in succession in a sequence, each spaced apart from one another by a gap, wherein a suction belt table 19 is arranged downstream of this transport device 18 which transports the sheets lying down along a linear transport path, wherein the suction belt table 19 has a catching device 58 with a catching position assumed as a result of an actuation for individual sheets which follow one another in a sequence, wherein the catching device 58 is in its catching position dependent on that transport device 18,which transports the sheets horizontally along a linear transport path and is arranged upstream of the suction belt table 19, catches and stacks the sheets fed to the suction belt table 19 on the suction belt table 19 before each transfer to a transport device downstream of the suction belt table 19. A control unit 71 provided for the suction belt table 19 actuates the catching device 58 depending on a malfunction occurring in a processing station downstream of the suction belt table 19 such that the catching device 58 assumes its catching position. In the preferred embodiment, the transport device 18 arranged upstream of the suction belt table 19, which transports the sheets horizontally along a linear transport path, belongs to a dryer 17.

[0043] This dryer 17 is arranged downstream of a processing station designed as a non-impact printing device 13. The suction belt table 19 is also preferably arranged upstream of a processing station designed as a coating device 22, in particular a varnishing device. The coating device 22 has, in particular, a transport cylinder 23 as a transport device for sheets to be transported. This transport cylinder 23 preferably cooperates with a printing unit cylinder 24 having an applicator roller 26 that is positioned or at least positionable against this printing unit cylinder 24, with at least one doctor blade 27 or a chambered doctor blade system 27 extending in the axial direction of the applicator roller 26. This machine arrangement is designed to transport the sheets at a transport speed of preferably several thousand sheets per hour, in particular approximately 10,000 sheets per hour.The transport device 18 arranged upstream of the suction belt table 19, which transports the sheets lying down along a linear transport path, is designed to transport the individual sheets which follow one another immediately in a sequence, each with a sheet gap preferably measuring approximately 20 mm.

[0044] This results in a suction belt table 19 for sheet-shaped substrates to be transported individually lying down, the suction belt table 19 being arranged between a transport device arranged upstream in the transport direction T of the substrates and a correspondingly downstream transport device, the suction belt table 19 having a catching device 58 with a catching position assumed as a result of its actuation for individual substrates following one another in a sequence, the catching device 58 in its catching position catching substrates fed to the suction belt table 19 from the upstream transport device before their respective transfer to the transport device arranged downstream of the suction belt table 19 on the suction belt table 19, ie preventing them from progressing in the transport direction T and stacking them.The transport device upstream of the suction belt table 19 has a translational transport path for the sheet-shaped substrates to be transported individually lying down, and / or the transport device downstream of the suction belt table 19 has a rotary transport path or a translational transport path for the sheet-shaped substrates to be transported. A control unit 71, in particular a digital one, is provided, wherein this control unit 71 actuates the catching device 58 as a function of a disturbance occurring along the transport path belonging to the transport device downstream of the suction belt table 19 such that the catching device 58 assumes its catching position.The catching device 58 has at least one pivotable stop surface 66 for substrates to be caught, wherein the stop surface 66 in question is arranged below a conveying plane E19 of the suction belt table 19 when the catching device 58 is not actuated by the control unit 71, and is positioned perpendicular to this conveying plane E19 when the catching device 58 is actuated by the control unit 71, pivoted through an opening 67 in the conveying plane E19 of the suction belt table 19, so that substrates transported on the suction belt table 19 abut against the at least one erected stop surface 66 protruding from the conveying plane E19 of the suction belt table 19. In its preferred embodiment, the catching device 58 has a slider-crank mechanism, wherein the slider-crank mechanism has a coupler 63 and a crank 62 interacting with the coupler 63, wherein the crank 62 is driven by a drive 59.The crank 62 is rotatably mounted at a pivot point D62 fixedly arranged in the suction belt table 19. The crank 62 is designed as an angle lever and has a short lever and a lever that is longer than this short lever. The short lever connects a pivot point G61, at which the drive 59 engages the crank 62, to the pivot point D62 of the crank 62. The longer lever of the crank 62 extends between its pivot point D62 and a pivot point G62, at which the crank 62 is connected to the coupling 63. The length ratio of the short lever and the longer lever of the crank 62 to one another is such that they translate a movement acting from the drive 59 of the catching device 58 on the coupling 63 into a faster speed. The transmission ratio i into a faster speed is preferably at least 1:5.An end point E2 of the coupling 63 facing away from the drive 59 of the catching device 58 is bidirectionally linearly movable along a path 64 arranged parallel to the conveying plane E19 of the suction belt table 19, wherein the end point E2 of the coupling 63 facing away from the drive 59 of the catching device 58 and the pivot point D62 of the crank 62 are arranged on a straight line G64 connecting these two points, wherein this straight line G64 runs parallel to the conveying plane E19 of the suction belt table 19. The at least one stop surface 66 for substrates to be caught is formed in a region between an end point E1 of the coupling 63 facing the drive 59 of the catching device 58 and the pivot point G62 at which the crank 62 is connected to the coupling 63.The slider-crank mechanism preferably has a central slider-crank, in which the three sections G62-D62; G62-E2; G62-E1 are each of equal length, and the end points E1; E2 of the coupling 63, including the pivot point G62 arranged therebetween, are all arranged on a straight line G63 connecting the end points E1; E2 of the coupling 63. The drive 59 of the catching device 58 is advantageously designed as a double-acting pneumatic cylinder 81, wherein this pneumatic cylinder 81 has a bottom chamber 68 and a bearing chamber 69 separated from the bottom chamber 68 by a cylinder piston 82 rigidly connected to its piston rod 61. The bearing chamber 69 is arranged at the end of the pneumatic cylinder 81 facing the pivot point G61, at which the drive 59 engages the crank 62.The bottom chamber 68 is arranged at the end of the pneumatic cylinder 81 facing away from the pivot point G61, at which the drive 59 engages the crank 62. A first pneumatic switching valve 86 is connected to the bottom chamber 68, and a second pneumatic switching valve 87 is connected to the bearing chamber 69. These two switching valves 86; 87 are each controlled by the control unit 71 of the catching device 58. The bottom chamber 68 either has barometric pressure, or the bottom chamber 68 has a differential pressure greater than the barometric pressure and less than the pressure in the bearing chamber 69. The piston rod 61 of the pneumatic cylinder 81 is retracted by pressurizing the bearing chamber 69, e.g., with 7 bar. The cylinder piston 82 of the pneumatic cylinder 81 works when retracting the piston rod 61 of the pneumatic cylinder 81 against in the bottom chamber 68 e.g.compressed air pre-pressurized at 2 bar, this compressed air being provided from a compressed air source 93 connected to the bottom chamber 68.

[0045] This also results in a suction belt table 19 for the horizontal transport of individual sheet-shaped substrates in a conveying plane E19, wherein the suction belt table 19 has a catching device 58 and at least one skid belt 48, wherein the catching device 58 and the at least one skid belt 48 are each controlled by a control unit 71 and are designed to assume one of two different operating states, wherein with respect to the catching device 58 and the at least one skid belt 48, the first operating state is an inactive operating state and the second operating state is an activated operating state, wherein the catching device 58 in its activated state has at least one stop surface 66 for substrates to be caught, which stop surface is arranged perpendicular to the conveying plane E19 of the suction belt table 19,wherein the at least one skid belt 48 is arranged in the transport direction T of the substrates by at least one substrate length extending in the transport direction T of the substrates in front of the at least one stop surface 66 arranged perpendicular to the conveying plane E19 of the suction belt table 19, wherein the at least one skid belt 48, in its activated state, is pivoted obliquely upwards out of the conveying plane E19 of the suction belt table 19 with its end directed in the transport direction T of the substrates at an acute angle opening in the transport direction T of the substrates. The suction belt table 19 is arranged between a transport device arranged upstream in the transport direction T of the substrates and a correspondingly downstream transport device,wherein the transport device upstream of the suction belt table 19 has a translational transport path for the sheet-shaped substrates to be transported individually lying down, and / or the transport device downstream of the suction belt table 19 has a rotary transport path or a translational transport path for the sheet-shaped substrates to be transported. Advantageously, a catching blower 51 with a plurality of blower nozzles arranged in a row extending transversely to the transport direction T of the substrates is arranged above the transport plane E19 of the suction belt table 19 in an area extending in the transport direction T of the substrates between the raised stop surface 66 of the catching device 58 and the at least one chute belt 48 pivoted obliquely upwards at an acute angle out of the conveying plane E19 of the suction belt table 19.wherein the catching blower 51, in its activated state, blows air from its nozzles, e.g., vertically in the direction of the conveying plane E19 of the suction belt table 19. The control unit 71 actuates the catching device 58 as a function of a disturbance occurring along the transport path belonging to the transport device downstream of the suction belt table 19 in such a way that the catching device 58 sets up its at least one stop surface 66 for substrates to be caught perpendicular to the conveying plane E19 of the suction belt table 19 and / or this control unit 71 actuates the at least one skid belt 48 as a function of the disturbance occurring along the transport path belonging to the transport device downstream of the suction belt table 19 in such a way thatthat the at least one skid belt 48 is pivoted at an acute angle obliquely upwards out of the conveying plane E19 of the suction belt table 19 and / or this control unit 71 actuates the catching blower 51 depending on the disturbance occurring along the transport path belonging to the transport device downstream of the suction belt table 19 such that the catching blower 51 blows air from its blowing nozzles in the direction of the conveying plane E19 of the suction belt table 19. The suction belt table 19 is preferably designed such thatthat in the transport direction T of the substrates, downstream of the catching device 58 above the conveying plane E19 of the suction belt table 19, a blow box 37 of an under-shingling device belonging to the suction belt table 19 is arranged. Furthermore, in the transport direction T of the substrates, upstream of the at least one skid belt 48 at the transition from the transport device upstream of the suction belt table 19 to this suction belt table 19, a guide device 42 extending transversely to the transport direction T of the substrates and having a plurality of lifting nozzles 43 is arranged. Also, in the area extending in the transport direction T of the substrates between the erected at least one stop surface 66 of the catching device 58 and the at least one skid belt 48 pivoted obliquely upwards at an acute angle out of the conveying plane E19 of the suction belt table 19, for example, at least one suction chamber 41 is arranged below the conveying plane E19 of the suction belt table 19.wherein the respective suction chamber 41 is set or at least adjustable in its respective pressure by the control unit 71, wherein a negative pressure is set or at least adjustable by the control unit 71 through suction bores 53 formed in the conveying plane E19 of the suction belt table 19 to the respective suction chamber 41 in the conveying plane E19 of the suction belt table 19. The negative pressure set in the conveying plane E19 of the suction belt table 19 by means of the suction chamber 41 is switched off in the event of a malfunction occurring along the transport route belonging to the transport device downstream of the suction belt table 19. The control unit 71 is preferably designed such thatthat it reduces the transport speed of the substrates, at least in the transport device upstream of the catching device 58 in the transport direction T of the substrates. Preferably, two parallel chute belts 48 in the form of circulating endless belts are provided in the transport direction T of the sheets, wherein these two chute belts 48 are arranged symmetrically to the center line M of the conveying plane E19 of the suction belt table 19.

[0046] In the following, it is assumed that a pneumatic drive 59 controlled by the control unit 71 actuates the catching device 58. As already explained, in the case of a stopper in operation, due to the high transport speed of several thousand sheets transported in the conveying plane E19 of the suction belt table 19 per hour, e.g., approximately 10,000 sheets per hour, and the relatively small gap of, e.g.,only approximately 20 mm between individual sheets directly following one another in their transport direction T, it is necessary to set up at least one stop surface 66 of the catching device 58 in the conveying plane E19 of the suction belt table 19 in a very short time and thus to insert it into the linear transport path of the sheets, so that a transfer of further sheets fed to the suction belt table 19 after the setting up of at least one stop surface 66 of the catching device 58 to a curved, in particular circular, transport path of a transport device downstream of the suction belt table 19 is effectively prevented. With these short switching times, a cylinder piston 82 in a pneumatic cylinder 81 exerts such a great force impulse on the inner stops of this pneumatic cylinder 81 as a result of the kinetic energy achieved that these stops are worn out in a very short time and are thus destroyed.In this respect, there is a need for a solution for improved damping at the inner stops of the pneumatic cylinder 81, so that this pneumatic cylinder 81 has sufficient wear resistance and thus the most unrestricted service life possible when used as described.

[0047] As from the Fig. 8 As can be seen, it is therefore proposed that a pneumatic circuit be provided for the operation of the double-acting pneumatic cylinder 81 of the catching device 58, which pneumatic circuit controls the movement of the cylinder piston 82 in such a way that a positive acceleration is set for the cylinder piston 82 in a first half of its stroke and a negative acceleration is set in a second half of its stroke following the first half. This pneumatic cylinder 81 has a bottom chamber 68 and a bearing chamber 69 separated from the bottom chamber 68 by the cylinder piston 82, wherein the cylinder piston 82 is fixedly connected to the piston rod 61. The bearing chamber 69 is arranged at that end of the pneumatic cylinder 81 which faces the pivot point G61 at which the drive 59 engages the crank 62.The bottom chamber 68 is located at the end of the pneumatic cylinder 81 facing away from the pivot point G61, where the drive 59 engages the crank 62. The cylinder piston 82 preferably has an end-position damping element 83; 84 on each side. The pneumatic circuit described in detail below implements a controlled acceleration phase and a controlled braking phase over the entire stroke of the cylinder piston 82 by changing a dynamic pressure equilibrium in the two chambers 68; 69 of the pneumatic cylinder 81.

[0048] The pneumatic circuit comprises a first pneumatic switching valve 86 and a second pneumatic switching valve 87, wherein both switching valves 86; 87 are each preferably electrically actuated by the control unit 71. Both switching valves 86; 87 are connected to their respective compressed air source 93 in one of their switching positions. Fig. 8 shows the operating position of the pneumatic cylinder 81 in which the piston rod 61 of the pneumatic cylinder 81 forming the drive 59 of the catching device 58 is retracted and thus the catching device 58 is activated, which means that the stop surface 66 of the catching device 58 is positioned in the conveying plane E19 of the suction belt table 19. A pressure reducer 88 is preferably connected upstream of at least the switching valve 86 for the bottom chamber 68 in order to build up a defined initial counterpressure in the bottom chamber 68 when the compressed air flows out. However, a pressure reducer 89 can also be connected upstream of the switching valve 87 for the storage chamber 69.In addition, a throttle valve 91 is arranged downstream of the switching valve 86 of the base chamber 68 in order to influence the outflow velocity of the compressed air from the base chamber 68 and thus the dynamic pressure curve in the pneumatic cylinder 81 and thus the speed of the cylinder piston 82 with this throttle valve 91, the cross-section of which is preferably adjustable. It can also be provided, for example, that a throttle valve 92 is also arranged in the air outlet from the bearing chamber 69 of the pneumatic cylinder 81 in order to limit the speed of the cylinder piston 82. The throttle valve 91 of the base chamber 68 and, if applicable, the throttle valve 92 of the bearing chamber 69 are only used when compressed air flows out of the respective chamber 68; 69 into the atmosphere.

[0049] Before the arresting device 58 is activated, the bearing chamber 69 of the pneumatic cylinder 81 is preferably depressurized, i.e. the pressure in it is, for example, equal to the barometric pressure. In an alternative embodiment, however, it can also be provided that the bearing chamber 69 of the pneumatic cylinder 81 is pressurized via the pressure reducer 89, if connected to it, with a pressure greater than the barometric pressure, for example with a pressure that corresponds to the pressure in the base chamber 68, i.e. preferably with a pressure of, for example, 2 bar. If the pressure set in both chambers 68; 69 is the same, the cylinder piston 82 is held in a stable end position. In the base chamber 68, which is pre-pressurized with compressed air, for example with 2 bar, an air mass that can be controlled via the pressure is provided, which is required to brake the travel movement of the cylinder piston 82 that occurs when the arresting device 58 is activated.The activation of the catching device 58, with the insertion of its at least one stop surface 66 into a sheet gap between the trailing edge of a preceding sheet and the leading edge of a first subsequent sheet to be caught, occurs when the two switching valves 86; 87 are actuated, in particular simultaneously, by the control unit 71. As a result, the storage chamber 69 is filled with compressed air from its compressed air source 93 at more than 5 bar, in particular at a pressure of, for example, 7 bar, and the air in the base chamber 68, which is pre-pressurized at approximately 2 bar, can now escape into the atmosphere in a controlled manner via the throttle valve 91. As a result, after a very short time, a differential pressure of approximately 5 bar and thus a corresponding force is present on the cylinder piston 82, which sets this cylinder piston 82 in motion.Controllable via the air mass trapped in the bearing chamber 69 and the opening cross-section of the throttle valve 91, the braking effect is such that the movement of the cylinder piston 82 initially experiences a very large acceleration with resulting speed, before this movement of the cylinder piston 82 is largely braked at the end by the actively clamped air column and only a remaining residual speed of less than, for example, 10% of the previously reached maximum possible speed is braked at the end position damping element 83 of the pneumatic cylinder 81. When the safety device 58 is activated, the cylinder piston 82 is accelerated over the first half of its stroke and braked over its second half. In the first half of its stroke, the cylinder piston 82 reaches its maximum possible speed. In the theoretically ideal case, the cylinder piston 82 arrives at its respective end position at zero speed.However, this is not achieved in real operation. Therefore, the small amount of residual energy remaining must be dissipated at the respective end-position damping element 83; 84. This very rapid movement of the cylinder piston 82 is transmitted with a high gear ratio by the crank 62 to the coupling 63, which is preferably arranged in a central slider-crank position.

[0050] Using the pneumatic circuit described and the pressure setting values ​​cited as examples, it is possible to bring at least one stop surface 66 of the catching device 58 into a catching position, even at the aforementioned high sheet transport speed through the aforementioned very narrow sheet gap. Advantageously, the solution presented here avoids high shock loads and load peaks throughout the entire kinematic system. This is because the clamped air column, which dampens the drive movement of the cylinder piston 82 at the end, particularly in the base chamber 68, effectively prevents destruction of the cylinder base. In addition, a secure end position of the cylinder piston 82 in its retracted state is achieved without additional mechanical elements and thus without additional costs. The pressure reduction in the storage chamber 69 also results in energy savings and a reduction in potential leakage.

[0051] The Fig. 9 bis 12 illustrate once again, by way of example, in a diagram plotted against the time t on the abscissa, the dynamic behavior of some physical variables with reference to the cylinder piston 82 of the pneumatic cylinder 81 during a switching operation when the catching device 58 of the relevant suction belt table 19 is moved from its initial position to its catching position, in particular actuated by a control signal from the control unit 71. Fig. 9 shows a change in position of the cylinder piston 82 between its two end positions in the pneumatic cylinder 81. A travel z and thus the stroke of the cylinder piston 82 is shown here, for example, with 10 mm. Fig. 10 shows, as an example, the speed v of the cylinder piston 82 during its movement along the travel path z. Fig. 11 shows, as an example, the corresponding acceleration a with which the cylinder piston 82 performs its movement along the travel z. In the Fig. 12 The piston force F exerted by the cylinder piston 82 is then shown as an example.

[0052] As described, a suction belt table 19 is produced for the horizontal transport of individual sheet-shaped substrates in a conveying plane E19, wherein the suction belt table 19 has a catching device 58 with at least one stop surface 66 for substrates to be caught, which stop surface 66 is positioned in its catching position in the conveying plane E19 of the suction belt table 19, wherein this at least one stop surface 66 is positioned from an inactive starting position of the catching device 58 into the catching position by a double-acting pneumatic cylinder 81 by a movement of its cylinder piston 82, wherein this pneumatic cylinder 81 has a bottom chamber 68 and a storage chamber 69 separated from the bottom chamber 68 by the cylinder piston 82, wherein a pneumatic circuit is provided to control the movement of the cylinder piston 82,The pneumatic circuit comprises a first pneumatic switching valve 86 connected to the bottom chamber 68 and a second pneumatic switching valve 87 connected to the storage chamber 69, wherein both switching valves 86; 87 are each preferably electrically actuated by the control unit 71. The catching device 58 comprises a slider-crank mechanism driven by the cylinder piston 82 of the pneumatic cylinder 81, as described above. The movement of the cylinder piston 82 is controlled by the control unit 71 in such a way thatthat a positive acceleration is set for the cylinder piston 82 in the first half of its stroke and a negative acceleration in the second half of its stroke following the first half. A pressure reducer 88 is connected upstream of at least the first switching valve 86 connected to the bottom chamber 68. Also downstream of at least the first switching valve 86 connected to the bottom chamber 68 is, for example, a throttle valve 91, preferably adjustable in its opening cross-section. The opening cross-section of the throttle valve 91 is set, for example, by the control unit 71, such that the movement of the cylinder piston 82 at the end of the second half of its stroke has a residual speed of less than 10% of the maximum speed previously reached in the first half of its stroke. The cylinder piston 82 preferably has an end-position damping element 83; 84 on each side.The residual speed of the cylinder piston 82 remaining at the end of the second half of its stroke is braked by the respective end-position damping element 83; 84. In the inactive initial position of the arresting device 58, at least the bottom chamber 68 of the pneumatic cylinder 81 is pressurized with a pressure greater than the barometric pressure, preferably with a pressure of, for example, 2 bar. To adjust the arresting position of the arresting device 58, the control unit 71 switches the first switching valve 86 connected to the bottom chamber 68 into a position that diverts the air mass from the bottom chamber 68, and simultaneously switches the second switching valve 87 connected to the bearing chamber 69, so that the bearing chamber 69 is pressurized with compressed air at a pressure of more than 5 bar.

[0053] In connection with the Fig. 2 It was described that the suction belt table 19 has, in its conveying plane E19, a switching region 52 extending in the transport direction T of the sheets, with a plurality of suction bores 53, wherein preferably a plurality of suction chambers 41 whose respective fluidic effects can be controlled are arranged below the conveying plane E19 of the suction belt table 19. These suction chambers 41 are preferably arranged one behind the other in the transport direction T of the sheets and, in particular, are switched or at least switchable individually and independently of one another in terms of their respective pressure.It was also explained that the suction bores 53 in the switching area 52 form a fluidic connection to at least one of the preferably several suction chambers 41 each arranged below the conveying plane E19 of the suction belt table 19, wherein in this switching area 52, a negative pressure can be set or at least adjusted at the suction bores 53 in the conveying plane E19 of the suction belt table 19 by the respective adjustment of the pressure in the respective suction chamber 41 by means of a suction device 72 controlled by the control unit 71. This negative pressure has the effect that a sheet resting on the at least one feed belt 54 in the conveying plane E19 of the suction belt table 19 is held in a frictionally or force-fitting manner. This is because the switching area 52 overlaps at least partially with the outline of the sheet to be caught. The feed belt 54 in question is, for example,is designed as an endlessly circulating suction belt, wherein a suction belt has a perforation at least in sections, so that the negative pressure set at the suction bores 53 in the conveying plane E19 of the suction belt table 19 can be applied to the resting sheet through the respective feed belt 54. The feed belt 54 is preferably designed as a flat belt or as a flat belt.

[0054] If a stopper is triggered and the at least one stop surface 66 of the catching device 58 is moved into its catching position, the frictional connection or force connection between the respective feed belt 54 and the sheet resting on it must be released within a very short time, because otherwise the sheet resting on the respective feed belt 54 would be pushed together, i.e. crumpled, upon impact against the at least one stop surface 66 of the catching device 58 protruding from the conveying plane E19 of the suction belt table 19. This is because at a transport speed of several thousand sheets per hour, e.g. of approximately 10.000 sheets per hour, it is neither possible to eliminate the negative pressure set there in the relevant suction chamber 41 by means of the suction device 72 controlled by the control unit 71, and thus the holding force acting on the sheets resting on the relevant feed belt 54, within the required short time, nor to stop the relevant feed belt 54 as such in good time before the sheet in question strikes the at least one stop surface 66 of the catching device 58. In order to avoid damage to a sheet lying on the relevant feed belt 54 when a stop occurs and which is the first to strike the at least one stop surface 66 of the catching device 58 protruding from the conveying plane E19 of the suction belt table 19, there is a need toThe frictional connection can be removed more quickly than if the suction device 72 of the suction chamber 41 in question is switched off and / or if the feed belt 54 in question is stopped.

[0055] As from the Fig. 13 It is therefore clearly proposed that at least one pneumatic timing valve 74 controlled by a control unit 71 be arranged in a supply line 73 pneumatically connecting the suction chamber 41 in question to the respective suction bores 53, wherein the timing valve 74 in question interrupts the pneumatic connection when the catching device 58 is moved into its catching position. In a preferred embodiment, the timing valve 74 in question is designed such that, at the same time as the pneumatic connection between the suction chamber 41 in question and the respective suction bores 53 is interrupted, a section of the supply line 73 between the timing valve 74 in question and the respective suction bores 53 is ventilated with barometric pressure or with a pressure that is 3% to 10%, preferably 5%, higher than the barometric pressure.The transport speed of the sheets corresponds to a cycle time in which immediately successive sheets reach the position of at least one stop surface 66 of the catching device 58 protruding from the conveying plane E19 of the suction belt table 19. A switching time of the respective timing valve 74 is shorter than the cycle time of immediately successive sheets and is preferably in a range between 20 ms and 100 ms, in particular 40 ms. The switching time of the respective timing valve 74 is the time beginning with the time of its actuation until reaching the time at which the respective timing valve 74 has stably changed from its first operating position to its second operating position.The control unit 71 is preferably designed such that it sets the respective timing valve 74 into the state interrupting the pneumatic connection between the respective suction chamber 41 and the respective suction bores 53 by the duration of a cycle time earlier before actuation of the catching device 58.

[0056] The advantage of this solution is that, in the event of a stopper being activated, even the first sheet caught by the catching device 58 is not pushed together or crumpled. Rather, the arrangement of at least one timing valve 74, controlled by the control unit 71, in the supply line 73 between the respective suction chamber 41 and the respective suction bores 53 ensures that the catching process is independent of the inevitable overrun of the at least one feed belt 54 after the detection of the stopper and / or a sustained suction effect of the respective suction chamber 41.

[0057] As already mentioned in connection with the Fig. 1 bis 3 As explained above, a plurality of sheets are fed to the suction belt table 19 by a transport device arranged directly upstream of the suction belt table 19, wherein these sheets are transported one behind the other, at least in this transport device and on the suction belt table 19, lying individually, each with a narrow gap between them, one behind the other, along a linear transport path. In the preferred embodiment, the transport of these sheets takes place by means of a plurality of transport belts arranged one behind the other in the transport direction T of the sheets, starting from the circulating transport belt 18 of the transport device arranged directly upstream of the suction belt table 19 via at least one transfer belt 44 belonging to the suction belt table 19, which is designed, for example, as a circulating flat belt preferably arranged in the central region of the conveying plane E19 of the suction belt table 19, wherein in the transport direction T the sheet after the transfer belt 44, for exampletwo parallel ski jump belts 48, e.g. in the form of circulating endless belts, are arranged, followed by at least one feed belt 54, in particular designed as a suction belt, and e.g. two parallel braking belts 56, each designed as a circulating endless belt.At each transition from a circulating endless belt - at a transition between two successive machine units such as from a non-impact printing device 13 or from a dryer 17 or from a suction belt table 19 to a respective different machine unit, at least one of these machine units having a transport device in the form of a circulating endless belt - to a transport device following the respective transport belt in the transport direction T of the sheets, there is a discontinuity 78 in the mechanical support of the sheets to be transported in the conveying plane E19 of the sheets due to a gap existing in this conveying plane E19 to a rotating deflection roller 76 of the respective transport belt with a width in relation to the thickness of the sheets in the range between 1 mm and 5 mm, this discontinuity 78 being particularly important at a high transport speed of several thousand sheets per hour, e.g. of approximately 10.000 sheets per hour carries the risk of operational disruption. This is because when sheets lying on a circulating belt are transported, there is a risk that the leading edge of the sheet in question will be deflected into the relevant discontinuity point 78 at the end of the transport path defined by the relevant conveyor belt due to its adhesion to the conveyor belt which is deflected at the end by means of the deflection roller 76, whereby such a sheet is prevented from further transport and itself becomes an obstacle for subsequent sheets. This problem occurs in particular at all transitions when at least one of the conveyor belts acting at the relevant transition has a width extending transversely to the transport direction T of the sheets of at least 25% of the width of the sheets to be transported. In the preferred embodiment, this is also the case at the transition from the conveyor belt arranged immediately upstream of the suction belt table 19, e.g.This is the case with the transport device belonging to a dryer 17 to this suction belt table 19.

[0058] It is therefore proposed to replace the point of discontinuity 78 of the mechanical support of the sheets to be transported in the conveying plane E19 with a pneumatic pressure force. This is achieved by arranging a guide device 42 extending transversely to the transport direction T of the sheets, preferably with a plurality of lifting nozzles 43 arranged in at least one row, at the transition from the transport device immediately upstream of the suction belt table 19 to this suction belt table 19. This guide device 42 with its plurality of lifting nozzles 43 is arranged in the transport direction T of the sheets, in particular upstream of the at least one jump belt 48 at the transition from the transport device upstream of the suction belt table 19 to this suction belt table 19. In an advantageous embodiment, the deflection roller 76 arranged at the point of discontinuity 78 has, for example,several nozzle-shaped openings, from each of which openings a compressed air jet emerges, one of the compressed air jets being directed at least in the direction of the at least one siphoning nozzle 43.

[0059] Fig. 14 shows an example of a top view of a section of the e.g. in connection with the Fig. 3 described suction belt table 19. A sheet-shaped substrate, preferably a printed sheet, called sheet 77 for short, is transferred to the suction belt table 19 on a conveying plane E19 as a result of its translational movement on a circulating conveyor belt 18 belonging, for example, to a dryer 17. Below the conveying plane E19 of the suction belt table 19 and preferably flush with this conveying plane E19 at the top, there is a rotating deflection roller 76 which moves the conveyor belt 18 in the transport direction T of the sheets 77 and deflects it at the end of the transport device immediately upstream of the suction belt table 19. During their transition from the transport device immediately upstream of the suction belt table 19 to the suction belt table 19, the sheets 77 must overcome a discontinuity 78 in their mechanical support located in the conveying plane E19. Transferred sheets 77 are, for example,by a transfer belt 44 belonging to the suction belt table 19, wherein this transfer belt 44 is designed, for example, as a revolving flat belt arranged in the central region of the conveying plane E19 of the suction belt table 19 and / or as a suction belt. Following the transfer belt 44 in the transport direction T of the sheets 77 are, for example, two parallel chute belts 48, for example in the form of revolving endless belts.

[0060] Fig. 15 shows schematically and in a highly simplified manner, by way of example, the guide device 42 arranged in a discontinuity point 78 relating to the mechanical support of the sheets 77 to be transported, with at least one lifting nozzle 43, preferably with a plurality of lifting nozzles 43, wherein this discontinuity point 78 is arranged, for example, between a circulating conveyor belt 16 belonging to a non-impact printing device 13 and a circulating conveyor belt 18 belonging to a dryer 17. A sheet 77 transported in the transport direction T tends, due to the rotation of the deflection roller 76, to be drawn with its leading edge into a gap located at the discontinuity point 78 in the periphery of the deflection roller 76, extending transversely to the transport direction T of the sheets 77, and thus to cause an operational disruption. Such a discontinuity point 78 in the mechanical support of the sheets 77 to be transported consists in a Fig. 1 digital printing machine, which transports sheets 77 horizontally, as shown by way of example, at several positions, at the respective transition to and after the non-impact printing device 13 and at the transition from the dryer 17 to the suction belt table 19.

[0061] The Fig. 16 bis 19 explain the functioning of the guide device 42 arranged in such a discontinuity point 78 with reference to a digital printing machine transporting sheets 77 horizontally at the transition of the sheets 77 from the non-impact printing device 13 to a dryer 17 immediately downstream of the non-impact printing device 13. These explanations also apply mutatis mutandis to all other positions at which a generic guide device 42 is arranged or at least can be arranged in the relevant machine arrangement designed as a digital printing machine.

[0062] Fig. 16 shows the initial situation for the function of the guide device 42 arranged in the discontinuity point 78. A sheet 77 resting on the circulating conveyor belt 16 belonging to the non-impact printing device 13 reaches the discontinuity point 78 with its leading edge at the transition of the sheets 77, e.g. from the conveyor belt 16 of the non-impact printing device 13 to a conveyor belt 18 of a dryer 17 arranged immediately downstream of the non-impact printing device 13.The guide device 42 has a pointed profile element 79 extending transversely to the transport direction T of the sheets 77, preferably in the form of a doctor blade, the tip of this profile element 79 being arranged approximately tangentially opposite the transport direction T of the sheets 77 to the transport belt 16 of the non-impact printing device 13, the tip of this profile element 79 being spaced apart from the transport belt 16 of the non-impact printing device 13, which is deflected on the rotating deflection roller 76, by a gap, this gap having a width in the range between 1 mm and 5 mm which is greater than the thickness of the sheets 77. In the profile element 79 there is at least one lifting nozzle 43 opening out in the direction of its tip, through which lifting nozzle 43, when the guide device 42, i.e. at least one of its lifting nozzles 43, is activated by the control unit 71, in a manner controlled by the control unit 71. Fig. 17 The air jet indicated by a directional arrow is directed against the conveyor belt 16 of the non-impact printing device 13 deflected at the deflection roller 76. In the state of the Fig. 17 In the activated guide device 42 shown, the sheet 77 lying on the conveyor belt 16 of the non-impact printing device 13 has rotated due to the rotation of the deflection roller 76 in comparison to the Fig. 16 shown initial situation, the gap formed by the guide device 42 is increasingly approached, with the front edge of the sheet 77 in question continuing to follow the curvature of the deflection roller 76 in a manner that potentially provokes a malfunction.

[0063] As can be seen from the Fig. 18 and 19As can be seen, the air jet blown out of the at least one lifting nozzle 43 arranged in the profile element 79 upon activation of the guide device 42 flows against the conveyor belt 16 of the non-impact printing device 13, which is deflected at the deflection roller 76. This air jet strikes the conveyor belt 16 in such a way that the direction of the core jet of this air jet intersects the circular circumferential line of the deflection roller 76 as a secant. In addition, this air jet is directed onto the conveyor belt 16 in such a way that a free upper boundary of this air jet facing the leading edge of the respective sheet 77 neither intersects nor exceeds a tangent between the circumferential line of the deflection roller 76 and the respective lifting nozzle 43 of the guide device 42.The air jet directed against the convex surface of the conveyor belt 16 of the non-impact printing device 13, which is deflected at the deflection roller 76, is directed there by the curvature of the deflection roller 76 in the direction of the approaching leading edge of the respective sheet 77. This air jet, which follows the curvature of the deflection roller 76 due to the Coanda effect and is converted into a wall flow, finally detaches the leading edge of the respective sheet 77 from the conveyor belt 16 of the non-impact printing device 13 (. Fig. 18 ) and, as the deflection roller 76 continues to rotate, the leading edge of the respective sheet 77 is increasingly lifted from the conveyor belt 16 of the non-impact printing device 13 due to the resulting back pressure ( Fig. 19 ), so that the leading edge of the sheet 77, which is still largely resting on the conveyor belt 16 of the non-impact printing device 13, is lifted onto the profile element 79 and thus onto the guide device 42 during its further transport. In the event that the transport device of the non-impact printing device 13 mentioned here, which is arranged immediately upstream of the discontinuity point 78 in the transport direction T of the sheets 77, has a plurality of, e.g. at least two, conveyor belts 16 arranged parallel to one another in the transport direction T of the sheets 77, it can be provided that at least one blower nozzle is arranged between adjacently arranged conveyor belts 16, which ejects compressed air in the direction of the sheet 77 resting on these conveyor belts 16.It can also be provided that the at least one conveyor belt 16 of the transport device arranged immediately upstream of the discontinuity point 78 in the transport direction T of the sheets 77 has raised longitudinal webs, wherein a groove is formed between each adjacent belt web, wherein the tip of the profile element 79 of the guide device 42 is arranged in a comb-like manner projecting into the grooves of the conveyor belt 16 having belt webs.

[0064] After the leading edge of the respective sheet 77 rests securely on the profile element 79, the guide device 42 is preferably deactivated by the control unit 71 by switching off the air jet flowing out of the at least one lifting nozzle 43. The air jet flowing out of the at least one lifting nozzle 43 is thus preferably active in a clocked manner, wherein this clock is synchronized with the arrival of the leading edge of the respective sheet 77 at the deflection roller 76 of the conveyor belt 16 deflected by this deflection roller 76. An air jet flowing out of the at least one lifting nozzle 43 of the guide device 42 is therefore preferably maintained only as long asuntil the leading edge of the respective sheet 77 has passed the gap at the discontinuity point 78 located in the periphery of the deflection roller 76 and extending transversely to the transport direction T of the sheets 77, and the leading edge of the respective sheet 77 has been lifted onto the profile element 79 of the guide device 42. This results in a machine arrangement with several processing stations, each processing sheet 77, wherein these processing stations are arranged one behind the other in the transport direction T of the sheets 77, wherein at least one of these processing stations has a first transport device transporting the sheets 77 along a linear transport path with at least one continuously circulating transport belt 16 deflected by a rotating deflection roller 76, wherein this first transport device is designed to transport individual sheets 77 in a sequence directly following one another, each lying on its at least one transport belt 16,wherein this processing station having the first transport device is followed by a second transport device (constructed according to the invention as a suction belt table 19) which also transports the sheets 77 lying on at least one endlessly circulating transport belt 18 along a linear transport path, wherein at the point of transfer of the sheets 77 to be transported from the transport belt 16 of the first transport device to the transport belt 18 of the second transport device following in the transport direction T of the sheets 77 (constructed according to the invention as a suction belt table 19), in a conveying plane E19 of these sheets 77 to be transported, a discontinuity point 78 is formed in the mechanical support of these sheets 77 to be transferred,wherein the deflecting roller 76 deflecting the at least one conveyor belt 16 of the first transport device is arranged at the point of discontinuity 78 in the mechanical support of the sheets 77 to be transferred. At this point of discontinuity 78, a guide device 42 extending transversely to the transport direction T of the sheets 77 is arranged, with a tapered profile element 79, the tip of this profile element 79 being directed counter to the transport direction T of the sheets 77 toward the conveyor belt 16 of the first transport device, wherein at least one lifting nozzle 43 is arranged in the profile element 79, the respective lifting nozzle 43 being designed to open towards the tip of this profile element 79. The tip of the profile element 79 is spaced apart from the conveyor belt 16 of the first transport device deflected at the rotating deflecting roller 76 by a gap.wherein this gap has a greater width in relation to the thickness of the sheets 77, in the range between 1 mm and 5 mm. In a preferred embodiment, a plurality of lifting nozzles 43 are arranged in the profile element 79 in a row extending transversely to the transport direction T of the sheets 77. When the guide device 42 is activated by a control unit 71, an air jet flowing out of the mouth of the respective lifting nozzle 43 is directed or at least directable against the conveyor belt 16 of the first conveyor device, which is deflected at the deflection roller 76, wherein this air jet is directed onto the conveyor belt 16 in such a way that a core jet of this air jet intersects the circumferential line of the deflection roller 76 as a secant. The air jet in question is also particularly directed in such a way that a free,the upper limit of this air jet facing a leading edge of a sheet 77 transported on the conveyor belt 16 of the first transport device neither intersects nor exceeds a tangent between the circumferential line of the deflection roller 76 and the respective lifter nozzle 43 of the guide device 42. The guide device 42 is activated by the control unit 71. The control unit 71 activates the guide device 42, for example, in a timed manner, wherein this time is synchronized with the arrival of the leading edge of the respective sheet 77 at the deflection roller 76 of the conveyor belt 16 of the first transport device deflected by this deflection roller 76. The guide device 42 is therefore preferably designed to maintain the air jet flowing out of the respective lifter nozzle 43 only as long asuntil the leading edge of the respective sheet 77 has passed the gap at the discontinuity point 78 located in the periphery of the deflection roller 76, extending transversely to the transport direction T of the sheets 77, and the leading edge of the respective sheet 77 has been lifted onto the tip of the profile element 79 of the guide device 42 by the air jet flowing from the respective lifter nozzle 43. The deflection roller 76, which deflects the at least one conveyor belt 16 of the first transport device, and the guide device 42, together with its profile element 79, are each arranged below the conveying plane E19 of the sheets 77 to be transported and preferably flush with this conveying plane E19.

[0065] Since the machine arrangement is designed as a digital printing machine, the processing station having the first transport device is designed either as a non-impact printing device 13 or as a dryer 17 or as a cooling section.

[0066] During a passage through a dryer 17, which dries, for example, using hot air and / or IR radiation, individual sheets previously printed in a non-impact printing device 13, lying flat on a conveyor belt 18, are subjected to a very high heat input. This causes these dried sheets to deform, i.e., in particular, to buckle, and thereby at least partially lose their flatness. Buckle-up of the dried sheets can reach such proportions that the sheet in question loses its adhesion to the conveyor belt 18 of the dryer 17 and is at least no longer transported in a precisely positioned manner.As a result, warped sheets provided at the exit of the dryer 17 can no longer be reliably received by a receiving belt 44 of a transport device arranged immediately downstream of the dryer 17 in the transport direction T of the sheets, which transport device belongs to a suction belt table 19 or preferably to a cooling section, due to inadequate detection. In a machine arrangement having multiple transport devices, this very quickly leads to an operational malfunction, particularly when such sheets follow one another at a transport speed of several thousand sheets per hour, e.g., approximately 10,000 sheets per hour. The reason for the inadequate detection of the warped sheets is, in particular, that the bending resistance forces inherent in the warping of the sheets in question are not overcome by a height-dependent suction force exerted by a suction belt.This problem of unreliable transfer of sheets that are curved in their edge area, in particular at their respective front edge, by a suction belt can also occur in the conveying plane E19 of the suction belt table 19 at a bend 46; 47, at which a curvature of the previously, e.g. horizontal, conveying plane is formed (. Fig. 2 and 3 ). However, in order to avoid damaging a print image previously applied to the top side of the relevant sheets in the non-impact printing device 13, it is prohibited to force curved sheets to flatten from above at the points mentioned in the machine arrangement described here, e.g. by means of a mechanical hold-down device.

[0067] In order to create the required frictional connection or force connection between a sheet that is curved, in particular due to heat input, and a suction belt and to transport this sheet with the suction belt in a positionally accurate manner, it is proposed to use the physical phenomenon of the aerodynamic paradox, in particular with regard to the lateral edge regions of a highly curved leading edge of a sheet to be taken over by a suction belt and / or a sheet to be transported by a suction belt.

[0068] The solution found is explained using the suction belt table 19 described above as an example. Fig. 20 shows an enlarged section of the Fig. 3 suction belt table 19 shown in a plan view, wherein this detail refers in particular to an arrangement of nozzles 49 in a region between one of the two skid belts 48 arranged parallel to one another in the transport direction T of the sheets and an edge 94 running longitudinally to the transport direction T of the sheets and laterally delimiting the conveying plane E19 of the suction belt table 19. The skid belts 48, as well as the at least one transfer belt 44 arranged upstream of them in the transport direction T of the sheets, are preferably in the form of circulating endless belts, in particular each designed as a suction belt, wherein the respective suction belt is in pneumatic operative connection with a suction device 72 and can exert a suction force on a lying sheet due to its at least section-wise perforation. The transport direction T of the sheets is in the Fig. 20 indicated by a directional arrow. A blowing direction of the nozzles 49 arranged in the above-mentioned area, ie a flow direction of an air stream emerging from these nozzles 49, is directed, for example, in the transport direction T of the sheets. In a preferred and in the Fig. 20 In the embodiment shown, the blowing direction of the nozzles 49 arranged in this area is directed either orthogonally to the edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19 or at an angle of 45° in the transport direction T to the edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19. It can also advantageously be provided that the blowing direction of a first subset of the nozzles 49 is directed, for example, orthogonally to the edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19 and the blowing direction of a second subset of the nozzles 49 is directed, for example, at an angle of 45° in the transport direction T to the edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19.

[0069] Fig. 21 shows an excerpt from the Fig. 2 shown side view of the suction belt table 19. It is intended that sheets fed to the suction belt table 19, in particular from a dryer 17, are to be grasped by at least one transfer belt 44 and transported further in the conveying plane E19 of the suction belt table 19. In particular in the area of ​​the at least one transfer belt 44 and in the area of ​​the jump belts 48 of the suction belt table 19 arranged downstream of the at least one transfer belt 44 in the transport direction T of the sheets or in the transport direction T of the sheets directly adjacent to a discontinuity point 78 in the mechanical support of the sheets to be transported, e.g. between the at least one transfer belt 44 belonging to the suction belt table 19 and a circulating conveyor belt 18 belonging to a dryer 17, a plurality of nozzles 49 are arranged ( Fig. 3 and 20). These nozzles 49 are designed in particular as Venturi nozzles and are connected to a compressed air source 93 by means of a pneumatically connecting supply line 96. In a preferred embodiment, a control valve 97 for adjusting and / or regulating the pressure of an air stream flowing out of the respective nozzle 49 is arranged in the supply line 96 connecting at least one of the nozzles 49 to the compressed air source 93. In a particularly advantageous embodiment, a timing valve 74, controlled, for example, by the control unit 71, is arranged between the respective control valve 97 and the respective nozzle 49 in the supply line 96 connecting at least one of the nozzles 49 to the compressed air source 93. Such a timing valve 74 is preferably controlled by the control unit 71 in such a way that at least one of the nozzles 49 is pressurized with compressed air at the exact moment when the leading edge of a sheet to be transported overlaps with the respective nozzle 49.The supply of compressed air to the relevant nozzle 49 is interrupted again by the control unit 71, in particular, when the leading edge of the relevant sheet to be transported is overlapped by a nozzle 49 closest in the sheet transport direction T. Furthermore, it is provided that, by means of the relevant timing valve 74, the supply of compressed air to the nozzles 49 arranged in the outline of a sheet to be caught is interrupted when the catching device 58 of the suction belt table 19 is switched to its catching position.

[0070] This results in a suction belt table 19 with at least one endlessly rotating transfer belt 44 designed as a suction belt for transferring sheets transported individually in a conveying plane E19 from a conveyor belt 18 of a dryer 17 arranged immediately upstream of the suction belt table 19 in the transport direction T of the sheets, wherein the suction belt table 19 has an arrangement of several nozzles 49 in its conveying plane E19 at least in a region between the at least one transfer belt 44 extending longitudinally to the transport direction T of the sheets and an edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19, wherein these nozzles 49 are each designed as Venturi nozzles,wherein a flow direction of at least a first subset of the nozzles 49 arranged in said region is directed in the transport direction T of the sheets and / or wherein a flow direction of at least a second subset of the nozzles 49 arranged in said region is directed orthogonally to the edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19 and / or wherein a flow direction of at least a third subset of the nozzles 49 arranged in said region is directed at an angle of 45° to the transport direction T of the sheets towards the edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19. In addition, at least one bend 46; 47 can be formed in the conveying plane E19 of the suction belt table 19 in the transport direction T of the sheets downstream of the at least one transfer belt 44,wherein at each of these bends 46; 47, the conveying plane E19 of the suction belt table 19 experiences a downward inclination with an acute angle in the range between 5° and 30° compared to the previous orientation of the conveying plane, wherein the arrangement of the nozzles 49 formed in the area between the at least one transfer belt 44 and the respective edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19 extends beyond the respective bend 46; 47 in the transport direction T of the sheets. In the said area or in the areas following one another in the transport direction T of the sheets, the nozzles 49 are each arranged, for example, in several rows each extending transversely to the transport direction T of the sheets (, Fig. 3 and 20 ).

[0071] The nozzles 49 are each connected to a compressed air source 93 by means of a pneumatically connecting supply line 96, wherein in at least one of the supply lines 96 connecting at least one of the nozzles 49 to the compressed air source 93, a control valve 97 is preferably arranged for adjusting and / or regulating the pressure of an air stream flowing out of the respective nozzle 49. In a preferred embodiment, a timing valve 74 is arranged between the respective control valve 97 and the respective nozzle 49 in the respective supply line 96 connecting at least one of the nozzles 49 to the compressed air source 93. The respective control valve 97 and / or the respective timing valve 74 are controlled by a control unit 71. The respective timing valve 74 is activated by the control unit 71 in particular when the leading edge of a sheet to be transported overlaps with the respective nozzle 49.The respective timing valve 74 is deactivated by the control unit 71, in particular, when the leading edge of the respective sheet to be transported is overlapped by a nozzle 49 closest to the sheet in the sheet transport direction T. In a particularly preferred embodiment, the suction belt table 19 has a catching device 58 with the previously described features for sheets to be caught, wherein the respective timing valve 74 is deactivated by the control unit 71 when the catching device 58 is switched to its catching position.

[0072] Since the nozzles 49 are each designed as a Venturi nozzle, they generate a suction force on a sheet to be transported which is many times greater in magnitude than a holding force generated by the suction flow on a suction belt arranged in the conveying plane E19 of the suction belt table 19, which holding force is provided for holding a sheet lying flat on the respective suction belt. In addition, a width of the area comprising the arrangement of nozzles 49 extending transversely to the transport direction T of the sheets is significantly larger than the width of the respective suction belt extending transversely to the transport direction T of the sheets, so that the width of the area comprising the arrangement of nozzles 49 lying outside the width of the respective suction belt is in a much more favorable ratio to the width of the highly curved leading edge of the respective sheet.Accordingly, the effective area formed by the arrangement of nozzles 49 and acting on the highly curved leading edge of the sheet in question is significantly larger than the effective area acting by the suction belt on the highly curved leading edge of the sheet in question. However, the larger the respective effective area, the better the bending resistance forces inherent in the curvature of the sheets in question can be overcome. Since the effect of the suction flow of the suction belt in question is height-dependent and decreases increasingly with increasing height, i.e. the distance between the suction belt in question and the sheet to be transported, the nozzles 49 designed as Venturi nozzles can cause the highly curved leading edge of the sheet in question to be sucked forward until the leading edge in question reaches the effective area of ​​the suction flow of the suction belt in question.Once the highly curved leading edge of the sheet in question is sufficiently deep within the effective range of the suction flow of the suction belt in question due to the action of the nozzles 49, this suction flow may be strong enough to suck the highly curved leading edge of the sheet in question over the remaining residual height onto the suction belt in question and to create the frictional or force-lock connection required for precise transport of the sheet in question. In a preferred embodiment, the control unit 71 is thus designed such that it first supplies the nozzles 49 with compressed air and only then, i.e. with a time delay, does a suction force exerted on the sheet by at least one transfer belt 44, each designed as a suction belt, begin to act. List of reference symbols

[0073] 01 Sheet feeder 02 First pile 03 Suction head 04 First oscillating gripper 05 First coating device 06 Transport cylinder 07 Printing unit cylinder 08 Former roller 09 Doctor blade; chambered doctor blade system 11 First gripper system 12 Transport belt 13 Non-impact printing device 14 First dryer 16 Transport belt 17 Second dryer 18 Transport device; conveyor belt 19 Suction belt table 21 Second oscillating gripper 22 Second coating device 23 Transport cylinder 24 Printing unit cylinder 26 Former roller 27 Doctor blade;Chamber doctor blade system 28 Second gripper system 29 Delivery 31 Third dryer 32 Second pile 33 Transfer drum 34 Transfer drum 36 Front lay 37 Blow box 38 Bulkhead 39 Opening 41 Suction chamber 42 Guide device 43 Lifter nozzle 44 Transfer belt 46 First bend 47 Second bend 48 Jump belt 49 Nozzle 51 Catcher blower 52 Switching area 53 Suction bore 54 Feed belt 56 Brake belt 57 Suction roller 58 Catch device 59 Drive 61 Piston rod 62 Crank 63 Coupling 64 Track 66 Stop surface 67 Opening 68 Bottom chamber 69 Storage chamber 71 Control unit 72 Suction device 73 Supply line 74 Cycle valve 76 Deflection roller 77Bend 78Point of discontinuity 79Profile element 81Pneumatic cylinder 82Cylinder piston 83End position damping element 84End position damping element 86First pneumatic switching valve 87Second pneumatic switching valve 88Pressure reducer 89Pressure reducer 91Throttle valve 92Throttle valve 93Compressed air source 94Edge 96Supply line 97Control valve ; aAcceleration FPiston force iTransmission ratio MCenter line tTime TTransport direction vSpeed ​​zTravel A51Distance B19Width D62Pivot point E1End point E2End point E19Conveyor plane G61Pivot point G62Pivot point G63Straight line G64Straight line

Claims

1. Printing press comprising a non-impact printing device (13), this printing press further comprising a plurality of processing stations for processing sheets (77), these processing stations being arranged one behind the other in a transport direction (T) of the sheets (77), one of these processing stations comprising the non-impact printing device (13), the relevant processing station comprising the non-impact printing device (13) or another of the processing stations comprising a first transport device that transports the sheets (77) along a linear transport section and comprises at least one continuously revolving conveyor belt (16) that is diverted at a rotating diverting roller (76), this first transport device being configured so as to transport adjacent individual sheets (77) that directly follow one another in a sequence lying flat in each case on its at least one conveyor belt (16), a second transport device transporting the sheets (77) lying flat along a linear transport section, likewise on at least one continuously revolving conveyor belt (18), being arranged downstream from this processing station comprising the first transport device, a discontinuity point (78) in the mechanical support of these sheets (77) to be transferred in each case being formed at the point at which the sheets (77) to be transported are transferred from the relevant conveyor belt (16) of the first transport device to the relevant conveyor belt (18) of the second transport device following in the transport direction (T) of the sheets (77), in a conveying plane (E19) of these sheets (77) to be transported, the diverting roller (76) diverting the at least one conveyor belt (16) of the first transport device being arranged at the discontinuity point (78) in the mechanical support of the sheets (77) to be transferred, a guide device (42), which extends transversely to the transport direction (T) of the sheets (77) and comprises a tapered profile element (79), being arranged at this discontinuity point (78), the guide device (42) being arranged at the discontinuity point (78) between the two conveyor belts (16; 18) arranged consecutively in the transport direction (T) of the sheets (77), the tip of the profile element (79) being oriented toward the relevant conveyor belt (16) of the first transport device counter to the transport direction (T) of the sheets (77), the tip of the profile element (79) being spaced apart by a gap from the relevant conveyor belt (16) of the first transport device which is diverted at the rotating diverting roller (76), the gap between the tip of the profile element (79) and the relevant conveyor belt (16) of the first transport device which is diverted at the rotating diverting roller (76) having a width in the range between 1 mm and 5 mm, a control unit (71) and at least one lifting nozzle (43) being provided, the at least one lifting nozzle (43) being activated, or at least being able to be activated, by the control unit (71), and the processing station arranged directly downstream from the processing station comprising the first transport device being configured as a suction belt feed table (19), characterized in that the at least one lifting nozzle (43) is arranged in the profile element (79) of the guide device (42), the relevant lifting nozzle (43) being configured to open in the direction of the tip of this profile element (79), the suction belt feed table (19) comprising a catching device (58) having a catching position, which is assumed as a result of an actuation, for adjacent individual sheets (77) that follow one another, and the catching device (58), in its catching position, catching sheets (77) on the suction belt feed table (19) that are fed from the first transport device (18), which is arranged upstream from the suction belt feed table (19), to the suction belt feed table (19) before they are transferred in each case to a transport device arranged downstream from the suction belt feed table (19), and stacking these.

2. Printing press according to claim 1, characterized in that the diverting roller (76) diverting the at least one conveyor belt (16) of the first transport device and the guide device (42) are each arranged beneath the conveying plane (E19) of the sheets (77) to be transported and arranged so as to end up flush with this conveying plane (E19) toward the top.

3. Printing press according to claim 1 or 2, characterized in that a plurality of lifting nozzles (43) are arranged in the profile element (79) in a row extending transversely to the transport direction (T) of the sheets (77).

4. Printing press according to claim 1 or 2 or 3, characterized in that, upon an activation of the guide device (42), an air jet flowing out of the opening of the respective lifting nozzle (43) is oriented against the relevant conveyor belt (16) of the first transport device which is diverted at the diverting roller (76).

5. Printing press according to claim 4, characterized in that the air jet that is oriented against the relevant conveyor belt (16) of the first transport device is oriented at the relevant conveyor belt (16) in such a way that a core jet of this air jet intersects a circumferential line of the diverting roller (76) in the form of a secant.

6. Printing press according to claim 4 or 5, characterized in that the air jet flowing out of the opening of the respective lifting nozzle (43) is oriented at the relevant conveyor belt (16) in such a way that a free upper boundary of this air jet which faces a leading edge of a sheet (77) being transported on the relevant conveyor belt (16) of the first transport device neither intersects nor overlaps with a tangent between the circumferential line of the diverting roller (76) and the relevant lifting nozzle (43) of the guide device (42).

7. Printing press according to claim 1 or 2 or 3 or 4 or 5 or 6, characterized in that the guide device (42) is activated in cycles by the control unit (71), this cycle being synchronized with the arrival of the leading edge of the respective sheet (77) at the diverting roller (76) of the relevant conveyor belt (16) of the first transport device which is diverted by means of this diverting roller (76).

8. Printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7, characterized in that the at least one lifting nozzle (43) of the guide device (42) is controlled by the control unit (71) in such a way that the guide device (42) only maintains the air jet flowing out of the relevant lifting nozzle (43) until the leading edge of the respective sheet (77) has passed the gap at the discontinuity point (78), which is located in the periphery of the diverting roller (76) and extends transversely to the transport direction (T) of the sheets (77), and the leading edge of the respective sheet (77) has been lifted onto the tip of the profile element (79) of the guide device (42) by the air jet flowing out of the relevant lifting nozzle (43).

9. Printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8, characterized in that the control unit (71) controlling the guide device (42) actuates the catching device (58) as a function of a disruption that has occurred in a processing station arranged downstream from the suction belt feed table (19) in such a way that the catching device (58) assumes its catching position.

10. Printing press according to claim 9, characterized in that the control unit (71) controlling the guide device (42) is configured so as to decrease a transport speed of the sheets (77) at least in the transport device arranged upstream from the catching device (58), in the transport direction (T) of the sheets (77), in the event that a disruption has occurred in a processing station arranged downstream from the suction belt feed table (19).

11. Printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10, characterized in that the suction belt feed table (19) comprises at least one continuously revolving receiving belt (44), which is configured as a suction belt, for receiving the sheets (77) transported individually, lying flat, in the conveying plane (E19) from the conveyor belt (18) arranged upstream from the suction belt feed table (19) in the transport direction (T) of the sheets (77), the suction belt feed table (19), in its conveying plane (E19), comprising an arrangement of a plurality of nozzles (49), at least in a region between the at least one receiving belt (44) extending longitudinally with respect to the transport direction (T) of the sheets (77) and an edge (94) that laterally delimits the conveying plane (E19) of the suction belt feed table (19), and the nozzles (49) arranged in the region between the at least one receiving belt (44) extending longitudinally with respect to the transport direction (T) of the sheets (77) and an edge (94) that laterally delimits the conveying plane (E19) of the suction belt feed table (19) each being configured as Venturi nozzles.

12. Printing press according to claim 11, characterized in that the arrangement of the Venturi nozzles starts, in the transport direction (T) of the sheets (77), at a distance of less than 200 mm downstream from the at least one lifting nozzle (43) .

13. Printing press according to claim 11 or 12, characterized in that the diverting roller (76) arranged at the discontinuity point (78) has, on its outer cylindrical surface, at least one nozzle-shaped opening, a compressed air jet exiting in each case from the relevant opening, with one of the compressed air jets being oriented at least in the direction of the at least one lifting nozzle (43).

14. Printing press according to claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13, characterized in that the first transport device comprises a plurality of conveyor belts (16) arranged parallel to one another in the transport direction (T) of the sheets (77), at least one blower nozzle, which ejects compressed air in the direction of a sheet (77) resting on these conveyor belts (16), being arranged between adjacent conveyor belts (16).

15. Printing press according to claim 1 or 2 or 3 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14, characterized in that the at least one conveyor belt (16) of the transport device arranged directly upstream from the discontinuity point (78), in the transport direction (T) of the sheets (77), comprises raised longitudinal ribs, a respective groove being formed between adjacent longitudinal ribs, and the tip of the profile element (79) of the guide device (42) being arranged so as to protrude into the grooves of the conveyor belt (16) comprising longitudinal ribs in a comb-like manner.