DE102021118473A1 - Suction belt table for sheet-shaped substrates to be transported lying individually - Google Patents

Abstract

The invention relates to a suction belt table for sheet-shaped substrates to be transported lying individually, the suction belt table being arranged between a transport device arranged upstream in the direction of transport of the substrates and a correspondingly arranged downstream transport device, the suction belt table having a catching device with a catching position assumed as a result of an actuation for successive ones in a sequence has individual substrates, the catching device in its catching position catching substrates supplied to the suction belt table by the upstream transport device before a respective transfer to the transport device arranged downstream of the suction belt table on the suction belt table.

Description

The invention relates to a suction belt table for sheet-shaped substrates to be transported lying individually, according to the preamble of claim 1.

The suction belt table described below is a machine unit for use in a machine arrangement that processes sheet-like substrates (referred to as sheets for short), such a machine arrangement having a plurality of machine units arranged one after the other in the transport direction of the sheets. At least two of these machine units have transport devices that transport the sheets. A suction belt table is used to transport sheets that have been processed or are to be processed along a linear transport path in the relevant machine arrangement, with these sheets being transported individually on at least one conveyor belt. While they are lying on the at least one conveyor belt, the individual sheets are each held in place by a suction force, d. H. held by a holding force caused by a suction flow frictionally or non-positively on the conveyor belt in question. The suction force is usually realized by a negative pressure acting on the respective sheet with reference to the surrounding barometric air pressure by means of a suction device.

In a preferred use, the suction belt table is arranged in a sheet-processing machine arrangement in the transport direction of the sheets after a dryer that dries the sheets. In a further development, the dryer is first followed by a cooling section for air conditioning and/or conditioning of the sheets heated in the dryer, so that the suction belt table is only arranged after the cooling section. A machine arrangement of the aforementioned type, whether with or without a cooling section after the dryer, usually has several processing stations arranged one behind the other in the transport direction of the sheets, each acting on the sheets, with each of these processing stations e.g. B. is formed as a machine unit in this sheet-processing machine assembly. As mentioned, the suction belt table can be arranged immediately after the dryer, so that no further processing station is arranged between the named dryer and the suction belt table, or only after the cooling section formed after the dryer. In the machine arrangement on which the preferred embodiment is based here, 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 lying flat along a linear transport section. The dryer is thus designed in particular as a continuous dryer for sheets in a single layer.

A further transport device 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 curved, in particular arc-shaped transport path. This further transport device is preferably arranged immediately after the suction belt table, i. H. In the relevant machine arrangement, no further processing station is arranged between the suction belt table and the downstream transport device. After leaving the suction belt table, the sheets to be transported by this machine arrangement thus change from a linear transport path to a curved transport path, in particular in the form of a circular arc. As can be seen below, a change from a linear transport path to a curved transport path, in particular a transport path designed in the shape of a circular arc, is sometimes very problematic on a suction belt table.

through the DE 10 2016 207 397 A1 a sheet-processing machine arrangement with a suction belt table arranged after a dryer that dries the sheets is known.

The invention is based on the object of creating a suction belt table for sheet-shaped substrates to be transported lying individually.

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

The advantages that can be achieved with the invention consist in particular in the fact that the catching device can be used to catch and stack sheets on the suction belt table before they are transferred to a transport device downstream of the suction belt table. Further advantages can be seen from the following description.

Exemplary embodiments of the invention are shown in the drawings and are described in more detail below.

• 1 einen Saugbändertisch in einer Bogen bearbeitenden Maschinenanordnung;
• 2 eine Seitenansicht des Saugbändertisches gemäß 1;
• 3 eine Draufansicht des in der 2 dargestellten Saugbändertisches;
• 4 eine Seitenansicht einer in den Saugbändertisch integrierten Fangeinrichtung;
• 5 die Fangeinrichtung der 4 in ihrer Parkposition;
• 6 die Fangeinrichtung der 4 in ihrer Fangposition;
• 7 einen Ausschnitt aus der 2 mit der Fangeinrichtung in ihrer Fangposition;
• 8 eine pneumatische Schaltung für den Betrieb der Fangeinrichtung;
• 9 ein Diagramm zum Hub des Zylinderkolbens eines die Fangeinrichtung antreibenden Pneumatikzylinders;
• 10 ein Diagramm zur Geschwindigkeit des Zylinderkolbens beim Betrieb der Fangeinrichtung;
• 11 ein Diagramm zur Beschleunigung des Zylinderkolbens beim Betrieb der Fangeinrichtung;
• 12 ein Diagramm zum Verlauf der Kolbenkraft des Zylinderkolbens beim Betrieb der Fangeinrichtung;
• 13 eine schematische Darstellung einer Schaltung zur Aufhebung eines Reibschlusses bzw. Kraftschlusses von auf dem Saugbändertisch gehaltenen Bogen;
• 14 einen Ausschnitt aus dem in der 3 in einer Draufsicht dargestellten Saugbändertisch;
• 15 eine Leiteinrichtung zwischen zwei in Transportrichtung der Bogen nacheinander angeordneten Transportbändern;
• 16 eine Ausgangssituation für die Funktion der Leiteinrichtung;
• 17 die Leiteinrichtung zu Beginn ihrer Aktivierung;
• 18 die aktivierte Leiteinrichtung;
• 19 die Leiteinrichtung bei der Übernahme eines Bogens;
• 20 einen Ausschnitt aus der in der 3 dargestellten Draufsicht auf den Saugbändertisch mit einer Düsenanordnung;
• 21 einen Ausschnitt aus der in der 2 dargestellten Seitenansicht des Saugbändertisches.

Show it:

• 1 a suction tape table in a sheet handling machine assembly;
• 2 a side view of the suction belt table according to FIG 1 ;
• 3 a top view of the in the 2 illustrated suction belt table;
• 4 a side view of a catching device integrated into the suction belt table;
• 5 the capture device 4 in their parking position;
• 6 the capture device 4 in their catch position;
• 7 a section of the 2 with the catching device in its catching position;
• 8th a pneumatic circuit for operating the capture device;
• 9 a diagram of the stroke of the cylinder piston of a pneumatic cylinder driving the catching device;
• 10 a diagram of the speed of the cylinder piston during operation of the catching device;
• 11 a diagram of the acceleration of the cylinder piston during operation of the catching device;
• 12 a diagram of the course of the piston force of the cylinder piston during operation of the catching device;
• 13 a schematic representation of a circuit for canceling a frictional connection or non-positive connection of held on the suction belt sheet sheet;
• 14 an excerpt from the in the 3 Suction belt table shown in a plan view;
• 15 a guide device between two conveyor belts arranged one after the other in the transport direction of the sheets;
• 16 an initial situation for the function of the control device;
• 17 the guidance device at the beginning of its activation;
• 18 the activated guidance device;
• 19 the guiding device when accepting a sheet;
• 20 an excerpt from the in the 3 illustrated top view of the suction belt table with a nozzle arrangement;
• 21 an excerpt from the in the 2 illustrated side view of the suction belt table.

An example of the machine arrangement mentioned at the outset is in 1 shown. Such a machine arrangement is z. B. from the mentioned DE 10 2016 207 397 A1 known. The machine arrangement selected as an example for processing sheets has, viewed in the transport direction T of the sheets, first a sheet feeder 01, in which a first stack 02 of sheets is ready for processing. The sheets are preferably rectangular substrates of paper, card or paperboard. Paper, cardboard and cardboard differ in their respective grammage, ie the weight in grams for one square meter of these sheets. Paper has a basis weight between 30 g/m ² and 150 g/m ² , cardboard has a basis weight between 150 g/m ² and 600 g/m ² and cardboard has a basis weight of more than 600 g/m ² . However, the sheets can also each be a substrate made of a plastic and/or formed as a thin sheet. Sheet feeder 01 can also be embodied as a magazine feeder having a plurality of first stacks 02.

A suction head 03 successively grips each of the stacked sheets from above and guides these sheets, e.g. B. by means of a first rocking gripper 04 and, if necessary, a transfer drum 34 interacting with the first rocking gripper 04 in a sequence of sheets separated from one another, e.g. g. to a first coating device 05, with this first coating device 05 e.g. B. is designed as a primer application device. The first coating device 05 has a z. B. designed as a pressure cylinder transport cylinder 06 and z. B. a printing unit cylinder 07 that interacts with this transport cylinder 06 and has an forme roller 08 that is or at least can be set against this printing unit cylinder 07, preferably in the form of an anilox roller, with at least one doctor blade being positioned in the axial direction of the forme roller 08 for optimal dosing of a coating material to be applied to the surface of the sheet 09 or a chamber doctor blade system 09 extends. Transport cylinder 06 transports the sheets held on its lateral surface along a curved transport path, in particular in the shape of a circular arc. The first coating device 05 carries the coating material, e.g. B. a primer either over the entire surface or only at certain, ie at predetermined locations, ie partially. The sheets are then transported by the transport cylinder 06 of the first coating device 05, e.g. B. by means of a first gripper system 11, in particular a first chain conveyor, and z. B. at least one first conveyor belt 12 is transferred to a non-impact printing device 13, with the first gripper system 11 and the first conveyor belt 12 interacting when 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, which has a linear transport section, with a transfer of the sheets to the non-impact Printing device 13 from the first conveyor belt 12 takes place. The first conveyor belt 12 is preferably designed as a circulating endless belt. In an advantageous embodiment, a first dryer 14 is provided in the area of the first gripper system 11, which dries the sheets that have been coated in the first coating unit 05. B. is designed as a hot air dryer and / or as a drying by IR radiation or UV radiation dryer.

The non-impact printing device 13 generally has at least four inkjet printing devices that can be controlled independently of one another, each of these inkjet printing devices printing a different printing color on the z. B. previously coated in the first coating device 05 side of the sheet. In the machine arrangement described here as an example, the non-impact printing device 13 preferably has a second conveyor belt 16, so that the sheets are printed by the inkjet printing devices while they are lying on this second conveyor belt 16. The second conveyor belt 16 is preferably designed as a circulating endless belt. A second dryer 17 drying the printed sheets is arranged downstream of the non-impact printing device 13 in the transport direction T of the sheets. B. is designed as a hot air dryer and / or as a drying by IR radiation or UV radiation dryer. The second dryer 17 has a transport device 18 which transports the sheets horizontally in a translatory manner, ie along a linear transport path. This transport device 18 is in the 1 machine arrangement shown as an example as a third conveyor belt 18 is formed. The third conveyor belt 18 is also preferably designed as a circulating endless belt. The transport device 18 of the second dryer 17 in this example transfers the dried sheets to a suction belt table 19, from which the sheets z. B. by means of a second oscillating gripper 21 and optionally a transfer drum 33 cooperating with the second oscillating gripper 21 to a second coating device 22 . The second coating device 22 is z. B. designed as a painting device, said second coating device 22 a coating material, z. B. applies a varnish in particular to a print image previously created in the non-impact printing device 13 . The second coating device 22 has a z. B. designed as a pressure cylinder transport cylinder 23, with this transport cylinder 23 z. B. a printing unit cylinder 24 interacts with an applicator roller 26 that is or at least can be positioned on this printing unit cylinder 24, preferably in the form of an anilox roller, with at least one doctor blade 27 or a chamber doctor blade system 27 extending in the axial direction of the applicator roller 26.

The sheets are then from the transport cylinder 23 of the second coating device 22 z. B. by means of a second gripper system 28, in particular a second chain conveyor, to a delivery 29, the sheets processed in this machine arrangement described as an example being deposited by the second gripper system 28 in the delivery, preferably in a second stack 32. In an advantageous embodiment, a third dryer 31 drying the sheets coated in the second coating device 22 is provided in the area of the second gripper system 28. B. is designed as a hot air dryer and / or as a drying by IR radiation or UV radiation dryer. The delivery 29 can also be embodied as a multi-stack delivery having a plurality of second stacks 32 . The one in the 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.

2 shows a side view of the suction belt table 19, as z. B. in a machine arrangement according to the 1 is arranged. The transport direction T of the sheets is in the 2 directed from right to left. So the suction belt table 19 individual sheets are sequentially from one in the 2 Only partially shown transport device 18 with a transport speed of several thousand sheets per hour, z. B. of about 10,000 sheets per hour. Adjacent individual sheets in their transport direction T, ie, individual sheets that follow one another directly 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 is only a few millimeters, e.g. B. about 20 mm. In the embodiment preferred 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, with this dryer 17 according to the in FIG 1 The machine arrangement illustrated by way of example is a second dryer 17, the sheets being transported lying, in particular lying on a conveyor belt, by this transport device 18 in a translatory manner, ie along a linear transport path. The suction belt table 19 initially accepts each individual sheet in a transport device 18 that is defined and conceptually transported by the suction belt table 19 upstream of it direction T of the sheet-extended conveying plane, this conveying plane preferably being oriented horizontally. In the further course of the transport path of the sheets, the conveying level E19 ( 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 front edge in the transport direction T against front lays 36 of the swing gripper 21 downstream of the suction belt table 19, with this swing gripper 21 being in the position shown in FIG 1 machine arrangement shown as an example is a second swing gripper 21 . Each sheet is transferred individually from this swing gripper 21 to a transfer drum 33 that interacts with this swing gripper 21 . The sheets are fully decelerated at the front lays and aligned in register.

In its preferred embodiment, the suction belt table 19 has a shingling device for sheets to be transported. Above the conveying plane E19 of the suction belt table 19, the shingling device extends preferably over the entire width of the sheets, i. H. transverse to the transport direction T of the sheets extending box-shaped housing, the so-called blower box 37, wherein in the blower box 37 on its side facing the conveying plane E19 of the suction belt table 19 in the transport direction T of the sheet several blower nozzles are arranged one behind the other. In the preferred embodiment, at least two rows of a plurality of blowing 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 blowing nozzles is directed essentially parallel to the conveying plane E19 of the suction belt table 19 against the transport direction T of the sheets. The respective blowing direction of the nozzles is z. B. determined by at least one channeling the flow of the blown air, each arranged and / or formed on the blow nozzle in question. The respective guide surface is on the side of the blow box 37 facing the conveying plane E19 of the suction belt table 19, e.g. B. as a projecting from this blow box 37 ramp. A blowing air flowing out of the respective blowing nozzles is preferably controlled by adjustable pneumatic valves, e.g. B. controlled in time and / or in intensity, the valves z. B. are or are controlled by a preferably digital control unit 71 processing a program. The valves are z. B. by the control unit 71 switched in particular in a cycle, wherein a cycle time and / or a clock frequency is preferably set depending on the feed of the suction belt table 19 fed sheet or are. Valves controlled in a cycle by a preferably digital control unit 71 are also referred to as cycle valves.

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 blower box 37 facing this conveying plane E19 in front of the first blower nozzle or the first blower nozzle row, the partition plate 38 separating the leading edge of a subsequent sheet, i . H. of a sheet, which directly follows a sheet lifted by the blast air from at least one of the blast nozzles of the blow box 37, against the suction effect caused by the blow nozzles arranged in the blow box 37. The sheet lifted by at least one of the blower nozzles or rows of blower nozzles of blower box 37 from the conveying plane E19 of suction belt table 19 channels the blower air flowing out of the at least one blower nozzle of blower box 37 and directs this blower air over the surface of partition plate 38 facing blower box 37. The partition plate 38 preferably has a concave curvature at its end located in the blowing direction, this curvature of the blowing air facing away from the conveying plane E19 of the suction belt table 19, i. H. there is an outflow direction directed away. The front edge of a sheet that directly follows a sheet lifted by the blown air from at least one of the blower nozzles remains unaffected by the partition plate 38 until the lifted sheet, due to its own progression of movement or feed in the transport direction T, with its rear end blow nozzle or blow nozzle row that was reached first in this sheet in its transport direction T. In order to prevent the front edge of the sheet that directly follows a sheet lifted by the blast air from at least one of the blast nozzles from being lifted prematurely due to the effect of the blast nozzle or row of blast nozzles exposed from the rear end of the preceding sheet, the blast air of the relevant Blowing nozzle or row of blowing nozzles is switched off by means of the associated valve depending on the movement progress or feed of the sheet currently being lifted 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.

A sheet raised by the blast nozzles or blast nozzle rows is due to the suction effect caused by the respective blast air (Venturi effect) above the conveying plane E19 of the suction tape table 19 in a certain, z. B. by a distance from the side of the blower box 37 measured towards the conveying plane E19 of the suction belt table 19, this floating height being dependent on the intensity of the blowing air in question and/or on the mass of the sheet in question and/or on the transport speed of the sheet in question is. To prevent arch z. B. large mass and / or high transport speed during their transport in the conveying plane E19 of the suction belt table 19 vibrate and begin to flutter, is in the area between the conveying plane E19 of the suction belt table 19 and the side of the blower box 37 facing this conveying plane E19 provided the raised arch supporting gusset, wherein the z. B. at an acute angle to the conveying plane E19 of the suction belt table 19 facing side of the blow box 37 arranged support plate z. B. is in the form of an air-permeable grid. The sheet lifted by the suction of the blast air and placed against the support plate is guided there in a smooth movement, ie without fluttering, in its transport direction T along this support plate. In the conveying plane E19 of the suction belt table 19, a plurality of openings 39 ( 3 ) is provided, through which air flows under the currently raised sheet to equalize the pressure. These openings 39 are z. B. circular with a diameter in the range of a few millimeters. In addition, below the conveying plane E19 of the suction belt table 19 are arranged a plurality of suction chambers 41 that can be controlled in terms of their respective fluidic effect. These suction chambers 41 are preferably arranged one behind the other in the transport direction T of the sheets and z. B. by means of a controlled by the control unit 71 suction device in particular individually and independently switchable in their respective pressure.

3 shows in a plan view the in the 2 Suction belt table 19 shown. The transport direction T of the sheets is as in FIG 2 directed from right to left. Thus, individual sheets are sequentially fed 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 are each at least on a conveyor belt 18, preferably on several, z. B. on two conveyor belts 18 arranged parallel to one another in the transport direction T of the sheets. These conveyor belts 18 are each z. B. as endlessly circulating flat bands or flat belts. Arranged at the transition from the transport device upstream of the suction belt table 19 to this suction belt table 19 is a guide device 42 which extends transversely to the transport direction T of the sheets and preferably has a plurality of lifting nozzles 43 arranged in at least one row. In the transport direction T of the sheets then follows at least one transfer belt 44, which z. g. as a circulating flat belt arranged in the central area of the conveying plane E19 of the suction belt table 19 and also preferably as a suction belt, with the suction belt having a perforation at least in sections. The sheets follow in the transport direction T after the transfer belt 44 or in its effective area in the conveying plane E19 of the suction belt table 19 at least one kink 46, preferably for a gradual curvature of the previously z. B. horizontal conveying plane several successive bends 46; 47, wherein at each of these kinks 46; 47, the conveying plane E19 of the suction belt table 19 experiences an optionally further downward inclination with an acute angle in the range between 5° and 30° compared to the previous orientation of the conveying plane. In the in the 2 and 3 example shown are two consecutive kinks 46; 47, the first bend 46 being arranged in the effective region of the transfer belt 44 and the second bend 47 being arranged at a small 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 z. B. symmetrical to the center line M the distance between the creases 46; 47 preferably spanning two ramp belts 48 arranged parallel to one another in the transport direction T of the sheets, e.g. B. in the form of encircling preferably each configured as a suction belt endless belts. The chute belts 48 are pivotably mounted at their rear end in the transport direction T of the sheets, which is thus reached first by a sheet brought in particular by the transfer belt 44, so that these chute belts 48 are inclined upwards at an acute angle opening in the transport direction T of the sheets can be pivoted out of the previous conveying plane E19 of the suction belt table 19 and, in their exposed operating state, form an erected ramp for the sheets to be transported. In the 2 the ramp belts 48 are shown in their normal operating state, ie in their normal operating state, ie not in the state in which they are pivoted out and are preferably flush with the remaining conveying plane E19 of the suction belt table 19 . In a preferred embodiment, several nozzles 49, each preferably designed as Venturi nozzles, are arranged at least in the respective longitudinal edge areas of the area of the conveying plane E19 of the suction belt table 19 spanned by the jump belts 48.

A catch blower 51 extending transversely to the transport direction T of the sheets is arranged at a distance A51 above the conveying plane E19 of the suction belt table 19 ( 2 and 3 ); Below the catch blower 51, in the conveying plane E19 of the suction belt table 19, particularly in its central area, begins a switching area 52 that extends in the transport direction T of the sheets and has a plurality of suction bores 53. The suction bores 53 in the switching area 52 form and open up a fluidic connection to at least one of the preferably several suction chambers 41 arranged below the conveying plane E19 of the suction belt table 19, wherein these suction chambers 41 are switched or at least can be switched 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 bores 53 and by the respective setting of the Pressure in the relevant suction chamber 41 in the conveying plane E19 of the suction belt table 19, a negative pressure is set or at least adjustable. The arranged in the switching area 52 suction holes 53 are z. B. symmetrically to the center line M of the conveying plane E19 of the suction belt table 19 in several, z. B. arranged in two rows and z. B. designed as a Bernoulli effect utilizing sucker. In the transport direction T, the sheet follows the switching area 52, e.g. B. overlapping with the switching area 52 at least one feed belt 54 designed in particular 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 blower box 37 of the shingling device. The at least one feed belt 54 is preferably designed as a circulating endless belt. In a preferred embodiment z. B. symmetrically to the center line M of the conveying plane E19 of the suction belt table 19 several, z. B. two feed belts 54 are provided. That area which extends in the conveying plane E19 of the suction belt table 19 opposite the blower box 37 and in which preferably several openings 39 ( 3 ) are provided, through which air flows under a sheet currently being lifted by the shingling device to equalize the pressure, the sheet extends at the edge in the conveying plane E19 of the suction belt table 19 in the transport direction T, at least partially lengthwise to the at least one feed belt 54.

In the transport direction T, the sheets follow the at least one feed belt 54 and/or the shingling device in the conveying plane E19 of the suction belt table 19, e.g. B. arranged symmetrically to the center line M preferably each as a circulating endless belt trained braking belts 56, which have the function of reducing the respective transport speed of the sheet before they are transferred to a suction belt table 19 immediately downstream transport device, z. B. to a swing gripper 21 to reduce. The sheets, which are preferably reduced in terms of their respective transport speed, are then gripped as they continue to move in the transport direction T by a rotating or at least rotatable suction roller 57 to which vacuum is applied by a suction device, with this suction roller 57 being positioned transversely to the transport direction T of the sheets, preferably at least over the entire Width of the sheet or over the entire width B19 of the suction belt table 19 extends. Thereafter, each of the sheets is successively and individually held by the suction roller 57 with its front edge in the transport direction T, i. H. its leading edge z. B. to the front lays 36 of the swinging gripper 21 immediately downstream of the suction belt table 19. Through the interaction of the shingling device, the braking belts 56, the suction roller 57 and the front lays 36 of the swinging gripper 21, the sheets that were previously transported individually lying one behind the other, each with a gap to one another, are transported transferred into an imbricated stream before these sheets to a suction belt table 19 immediately downstream transport device, z. B. to a swing gripper 21, to then be transferred to a suction belt table 19 having this z. B. designed as a digital printing machine machine assembly rotating to a coating device 22, z. B. to be transported to a coating device 22 designed as a painting device and through it.

During the operation of such a machine arrangement, in particular in the industrial printing process of a digital printing machine, there can always be a fault in a suction belt table 19 downstream, e.g. B. come as a coating device 22 designed processing station. A serious disturbance in such a processing station means that the transfer of sheets to the transport device downstream of the suction belt table 19 has to be interrupted abruptly. This operating case forms a stopper. With a stopper, sheets in transit must be collected and stacked efficiently in the machine assembly very quickly. In a machine arrangement forming a digital printing machine, however, it is not possible due to the structural conditions, in particular due to a lack of the required space in height a processing station upstream of the suction belt table 19, e.g. g. in a first coating unit 05 or in the non-impact printing unit 13 or in a dryer 17 downstream of the non-impact printing unit 13, to collect and stack a large number of sheets transported in rapid succession, i.e. at a high transport speed, closely spaced one behind the other . It is not a satisfactory solution to arrange an ejection device in the transport direction T of the sheets after the dryer 17, which is arranged downstream of the non-impact printing device 13, and before the suction belt table 19, with this ejection device still being out of the non-impact printing device 13 in the event of a stopper downstream dryer 17 passes out sheet under the suction belt table 19 and deposits it there. Because the filing of the sheets there succeeds only 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 ergonomically very unfavorable conditions. In addition, there is also hardly any possibility of arranging the necessary conveying elements in the area of the ejection device for taking over the flow of individual sheets from the dryer 17, which is to be carried out in trouble-free operation. Without such suitable conveying elements, however, there can 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. The result would be 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 . However, it should be noted here that it is not possible to carry out continuous shingling on the shingling device of the suction belt table 19 for stack formation. This is because the nozzles that suck from above onto the rear edge of the relevant sheet for shingling are ineffective at the latest with an immediately following sheet, because the previous sheet is not transported away when the sheets are collected and thus shields the suction effect on the next sheet below.

A suction belt table 19 with a catching device 58 is therefore proposed, with which catching device 58 successive individual sheets 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 a shingling device, is arranged in the transport direction T of the sheets after a dryer 17, which is arranged 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 arranged directly upstream of this suction belt table 19 to a curved, in particular arc-shaped, transport path arranged immediately downstream of this suction belt table 19.

The proposed catching device 58 has a slider-crank mechanism whose coupler has at least one stop surface 66 for the sheets to be caught. Details of the catching device 58 and how it works are described below with reference to the 4 until 6 described.

4 shows an example of a side view of the catching device 58. As long as it is inactive, i.e. not actuated by the control unit 71, for example, this catching device 58 is arranged 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 at the end of the switching region 52 of this suction belt table 19, which has suction bores 53, away from a line drawn from the catcher blower 51 perpendicularly to the conveying plane E19 of the suction belt table 19 corresponding to the distance A51. The catcher device 58 has a drive 59, which is preferably designed as a double-acting pneumatic cylinder 81 is whose cylinder piston 82 can be pressurized on both sides with compressed air ( 8th ). A bidirectional, 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, the crank 62 being rotatably mounted in 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 longer lever than this short lever, the short lever linking 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 connects. The crank 62 is in turn connected to a coupler 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 form a slider crank mechanism in their interaction, with an end point E2 of the coupling 63 facing away from the drive 59 of the catching device 58 being 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 coupler 63 facing away from the drive 59 of the safety gear 58 and the pivot point D62 of the crank 62 consequently lie on a straight line G64 connecting them to one another, this straight line G64 running parallel to the conveying plane E19 of the suction belt table 19.

The coupler 63 has at least one stop surface 66 for sheets to be caught in a region 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 coupler 63 . The stop surface 66 in question is thus preferably a component of the coupler 63. The stop surface 66 in question is preferably made of a plastic, e.g. B. from a polyamide (abbreviation PA) or from a thermoplastic material such as. B. polyoxymethylene (abbreviation POM).

In a preferred embodiment, the slider crank mechanism has a central slider crank, which means that the three in the 4 routes G62-D62, G62-E2 and G62-E1 shown are each of the same length and the end points E1; E2 of the coupler 63 together with the articulation point G62 arranged between them all on one end point E1; E2 of the coupler 63 connecting straight lines G63. The length ratio of the short lever and the longer lever of the crank 62 to one another is such that they increase the speed of a movement triggered by the drive 59 of the catching device 58 and acting on the coupler 63 . The speed-up ratio i is preferably at least 1:5 (i=0.2).

In connection with the 5 until 7 the functioning of the catching device 58 can be seen. the 2 and 5 show the catching device 58 in its inactive, ie non-actuated starting position or parking 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 unhindered in its conveying plane E19, which in the 5 is indicated by two consecutive directional arrows. How from the 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 loading of this pneumatic cylinder 81 with compressed air and the end point E2 of the coupler 63 facing away from the drive 59 of the catching device 58 takes its place on the path 64 from the drive 59 the capture device 58 furthest position.

the 6 and 7 show the catching device 58 in its catching position. In the catching position, the at least one stop surface 66, which is preferably formed on the coupler 63, pierces through a corresponding, e.g. B. slot-shaped opening 67 ( 3 ) the conveying plane E19 of the suction belt table 19 and is set up by a pivoting movement 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 ( 6 and 7 ), So that on the suction belt table 19 transported sheets against the at least one established, z. B. push stop surface 66 protruding about 50 mm from the conveying plane E19 of the suction belt table 19 (see directional arrows in the 6 ) and caught in this way and prevented from further movement progress in the transport direction T. Sheets that are transported one after the other and each hit against the raised stop surface 66 are deposited one on top of the other in the transport direction T 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 loading of this pneumatic cylinder 81 with compressed air and the end point E2 of the coupler 63 facing away from the drive 59 of the catching device 58 takes its path 64 to the drive 59 the catching device 58 next layer.

7 shows an excerpt from the 2 with jump belts 48, which are shown in their from the previous conveying level E19 of the suction belt table 19 in an acute angle opening in the transport direction T of the sheets obliquely upwardly exposed operating state, and with a z. B. activated by the control unit 71 catch blower 51, its activation in the 7 is indicated by a blow direction arrow directed to the conveying plane E19 of the suction belt table 19 .

When the operating case forming a stopper occurs, in that in a downstream of the suction belt table 19, e.g. If, for example, a processing station configured as a coating device 22 of the machine arrangement that has the suction belt table 19 suffers a serious malfunction, with the result that the transfer of sheets to the transport device downstream of the suction belt table 19 has to be interrupted abruptly, then the catching device 58 is switched to its catching position by the Drive 59 of the catching device 58 is actuated automatically, in particular under program control, by a control unit 71, generally by the control unit 71 that controls other functions, preferably all of the functions of the suction belt table 19. This control unit 71 controls z. B. also the valves of the blower box 37 ( 2 ). At the same time as the safety catch 58 is actuated, e.g. B. the transport speed of the sheets can be reduced, by the transport devices arranged upstream of the catching device 58 in the transport direction T of the sheets reducing their respective transport speed. 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 when the catching device 58 is actuated, e.g. B. the transport speed of the ski jump 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 any case, with this suction chamber 41 by means of the suction belt table in the conveying plane E19 19 formed suction bores 53 is fluidically connected to the relevant switching area 52 and at least partially overlaps with a floor plan of the stack to be formed of the sheets to be caught. The at least one stop surface 66 of the catching device 58 is then shot 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 at the same time; 87, so that the piston rod 61 of the pneumatic cylinder 81 forming the drive 59 of the catching device 58 is retracted.

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 fixedly connected to the piston rod 61, with a first pneumatic switching valve 86 being connected to the bottom chamber 68 and a second pneumatic switching valve 87 to the Storage chamber 69 is connected. 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 variant, the bottom chamber 68 can have a differential pressure that is greater than the barometric pressure and less than the pressure in the storage chamber 69 . In a preferred embodiment, the piston rod 61 of the drive 59 of the catching device 58 forming pneumatic cylinder 81 by pressurizing the bearing chamber 69 z. B. retracted with 7 bar. The cylinder piston 82 of the pneumatic cylinder works in this retraction of the piston rod 61 of the pneumatic cylinder 81 against in the bottom chamber 68 z. B. with 2 bar prestressed compressed air that can escape throttled via the open pneumatic switching valve 86 of the bottom chamber 68 and optionally via a subsequent throttle valve 91. The braking effect of this back pressure only sets in relatively late, so that the movement of the cylinder piston 82 and thus also the piston rod 61 experiences a very high acceleration with the resulting speed at the beginning, before the movement of the cylinder piston 82 is braked at the end by the actively clamped air column and the residual speed at an end position damping element 83; 84 of the pneumatic cylinder 81 is braked. This very rapid movement of the cylinder piston 82 is greatly increased by the crank 62 to the coupling 63 arranged in the center position of the crank, preferably with an increased transmission ratio i of at least 1:5 (i=0.2).

With the proposed slider-crank mechanism, it is possible to achieve the at least one stop surface 66 of the catching device 58 even at a high transport speed of the sheets of several thousand sheets per hour, z. B. of about 10,000 sheets per hour by a z. B. only about 20 mm measuring sheet gap to bring through into the catch position. The response time that can be achieved with the proposed slider-crank mechanism thus clearly surpasses the switching times of simple folding and/or sliding mechanisms, the z. B. of switching magnets or directly, d. H. are driven gearlessly by a pneumatic cylinder 81. A further advantage of the solution found is that the proposed slider-crank mechanism is designed to be comparatively simple and space-saving.

This results in a machine arrangement with a plurality of processing stations that each process sheets, with these processing stations being arranged one behind the other in the transport direction T of the sheets, with at least one of these processing stations having a transport device 18 that transports the sheets lying flat along a linear transport path, with this transport device 18 in a sequence directly successive individual sheets spaced apart from one another by a gap, a suction belt table 19 being arranged downstream of this transport device 18, which transports the sheets horizontally along a linear transport path, the suction belt table 19 having a catching device 58 with a catching position assumed as a result of an actuation for in a sequence having successive individual sheets, the catching device 58 in its catching position being separated from that transport device 18 which has the sheets lying transported along a linear transport path and is arranged upstream of the suction belt table 19, the suction belt table 19 supplied sheets before a respective transfer to a suction belt table 19 downstream transport device on the suction belt table 19 catches and stacks. A control unit 71 provided for the suction belt table 19 actuates the catching device 58 depending on one of the suction belts table 19 downstream processing station such that the catching device 58 assumes its catching position. In the preferred embodiment, the transport device 18, which is arranged upstream of the suction belt table 19 and transports the sheets lying flat along a linear transport path, belongs to a dryer 17. This dryer 17 is z. B. downstream of a processing station designed as a non-impact printing device 13 . The suction belt table 19 is also preferably arranged in front of a processing station designed as a coating device 22, in particular as a painting device. Coating device 22 has a transport cylinder 23 in particular as the transport device for sheets to be transported, with this transport cylinder 23 preferably a printing unit cylinder 24 interacting with an applicator roller 26 that is or at least can be thrown onto this printing unit cylinder 24, with at least one squeegee moving in the axial direction of applicator roller 26 27 or a chamber doctor blade system 27 extends. This machine arrangement is designed to transport the sheets at a transport speed of preferably several thousand sheets per hour, in particular about 10,000 sheets per hour. The transport device 18 upstream of the suction belt table 19, which transports the sheets lying flat along a linear transport path, is designed to transport the individual sheets that follow one another directly in a sequence, each with a sheet gap of preferably about 20 mm.

This results in a suction belt table 19 for sheet-like substrates to be transported lying individually, with the suction belt table 19 being arranged between a transport device arranged upstream in the transport direction T of the substrates and a correspondingly arranged downstream transport device, with the suction belt table 19 having a catching device 58 with a catching position assumed as a result of its actuation for individual substrates that follow one another in a sequence, with the catching device 58 in its catching position catching substrates fed to the suction belt table 19 from the upstream transport device before they are transferred to the transport device arranged downstream of the suction belt table 19 on the suction belt table 19, i.e. on a point directed in the transport direction T Movement progression hinders and preferably stacks. The transport device upstream of the suction belt table 19 has a translatory transport path for the sheet-shaped substrates to be transported lying individually and/or the transport device arranged downstream of the suction belt table 19 has a rotary transport path or a translatory transport path for the sheet-shaped substrates to be transported. A control unit 71, in particular digital, is provided, this control unit 71 actuating the catching device 58 depending on a disturbance that has occurred along the transport route belonging to the transport device downstream of the suction belt table 19 in such a way 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, the relevant stop surface 66 being arranged below a conveying plane E19 of the suction belt table 19 when the catching device 58 is in the non-actuated state of the control unit 71 and 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 and positioned perpendicularly to this conveying plane E19, so that substrates transported on the suction belt table 19 collide with the at least one 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, the slider-crank mechanism having a coupling 63 and a crank 62 interacting with the coupling 63 , the crank 62 being driven by a drive 59 . The crank 62 is rotatably mounted in a pivot point D62 fixed in the suction belt table 19, with the crank 62 being designed as an angled lever and having a short lever and a lever which is longer than this short lever, the short lever having a pivot point G61, at which the drive 59 acts on the crank 62, to the pivot point D62 of the crank 62, with the longer lever of the crank 62 extending 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 increase the speed of a movement acting on the coupler 63 from the drive 59 of the catching device 58 . The speed-up ratio i is preferably at least 1:5. An end point E2 of the coupler 63 facing away from the drive 59 of the catching device 58 can be moved linearly and bidirectionally along a path 64 arranged parallel to the conveying plane E19 of the suction belt table 19, with the end point E2 facing away from the drive 59 of the catching device 58 being the coupler 63 and the pivot point D62 of the crank 62 are arranged on a straight line G64 connecting these two points with one another, this straight line G64 running 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 . That Slider crank mechanism preferably has a centric slider crank, in which the three routes G62-D62; G62-E2; G62-E1 are each of the same length and the end points E1; E2 of the coupler 63 together with the articulation point G62 arranged between them all on one end point E1; E2 of the coupling 63 connecting straight lines G63 are arranged. The drive 59 of the catching device 58 is advantageously designed as a double-acting pneumatic cylinder 81, this pneumatic cylinder 81 having a bottom chamber 68 and a bearing chamber 69 separated from the bottom chamber 68 by a cylinder piston 82 firmly connected to its 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 acts on the crank 62 . The floor chamber 68 is arranged at that end of the pneumatic cylinder 81 which faces away from the pivot point G61, at which the drive 59 acts on 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 storage 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 storage chamber 69 . The piston rod 61 of the pneumatic cylinder 81 is compressed by pressurizing the bearing chamber 69 z. B. retracted with 7 bar. The cylinder piston 82 of the pneumatic cylinder 81 works against the retraction of the piston rod 61 of the pneumatic cylinder 81 in the bottom chamber 68 z. B. compressed air prestressed at 2 bar, this compressed air being provided from a compressed air source 93 connected to the bottom chamber 68 .

There is also a suction belt table 19 for horizontally transporting individual sheet-like substrates in a conveying plane E19, with suction belt table 19 having a catching device 58 and at least one chute belt 48, with catching device 58 and the at least one chute belt 48 each being controlled by a control unit 71, optionally with one are designed to accommodate two different operating states, with the first operating state being an inactive operating state and the second operating state being an activated operating state with respect to the safety device 58 and the at least one ski jumping ramp 48, with the safety device 58 in its activated state being at least one vertical to the conveying plane E19 of the suction belt table 19 has stop surface 66 for substrates to be caught, the at least one jump belt 48 extending in the transport direction T of the substrates by at least one in the transport direction T of the substrates substrate length in front of the at least one stop surface 66 set up perpendicularly to the conveying plane E19 of the suction belt table 19, the at least one skid belt 48 being in its activated state with its end pointing in the transport direction T of the substrates at an acute angle opening in the transport direction T of the substrates at an angle is pivoted out of the conveying plane E19 of the suction belt table 19 at the top. In this case, the suction belt table 19 is arranged between a transport device arranged upstream in the transport direction T of the substrates and a correspondingly arranged downstream transport device, the transport device arranged upstream of the suction belt table 19 having a translational transport path for the sheet-shaped substrates to be transported lying individually and/or the transport device arranged downstream of the suction belt table 19 having a has a rotary transport path or a translatory transport path for the sheet-shaped substrates to be transported. Advantageously, in a region above the conveying plane E19 of the suction belt table 19 that extends 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 that is pivoted obliquely upwards out of the conveying plane E19 of the suction belt table 19 at the acute angle a catch blower 51 with a plurality of blower nozzles arranged in a row extending transversely to the transport direction T of the substrates, the catch blower 51 blowing air from its blower nozzles z. B. blows vertically in the direction of the conveying plane E19 of the suction belt table 19. The control unit 71 actuates the catching device 58 depending on a disruption that has occurred along the transport route 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 perpendicularly to the conveying plane E19 of the suction belt table 19 and/or this control unit 71 actuates the at least one take-off belt 48 as a function of the disruption that has occurred along the transport route belonging to the transport device downstream of the suction belt table 19 in such a way that the at least one take-off belt 48 is pivoted obliquely upwards at the acute angle out of the conveying plane E19 of the suction belt table 19 and/or this control unit 71 actuates the blower 51 depending on the disruption that has occurred along the transport route belonging to the transport device downstream of the suction belt table 19 in such a way that the blower 5 1 blast air blows out of its blast nozzles in the direction of the conveying plane E19 of the suction belt table 19. The suction belt table 19 is preferably designed in such a way that in the transport direction T of the substrates A blower box 37 of a shingling device belonging to the suction belt table 19 is arranged after the catching device 58 above the conveying plane E19 of the suction belt table 19 . In addition, in the transport direction T of the substrates in front of the at least one jump belt 48 at the transition from the transport device arranged upstream of the suction belt table 19 to this suction belt table 19, e.g. B. arranged transversely to the transport direction T of the substrates extending guide 42 with a plurality of lifting nozzles 43. Also, in the area below the conveying plane E19 of the suction belt table 19, which extends in the transport direction T of the substrates between the raised at least one stop surface 66 of the catching device 58 and the at least one chute belt 48 that is pivoted obliquely upwards out of the conveying plane E19 of the suction belt table 19 at the acute angle e.g. B. at least one suction chamber 41 is arranged, the respective pressure of the respective suction chamber 41 being set or at least adjustable by the control unit 71, whereby from 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 a negative pressure is set or at least adjustable. 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 fault occurring along the transport path belonging to the transport device downstream of the suction belt table 19 . The control unit 71 is preferably designed in such a way that it reduces a transport speed of the substrates at least in the transport device arranged upstream of the catching device 58 in the transport direction T of the substrates. Preferably, two parallel ramp belts 48 are provided in the transport direction T of the sheets in the form of circulating endless belts, with these two ramp belts 48 being arranged symmetrically to the center line M of the conveying plane E19 of the suction belt table 19.

In the following it is assumed that a pneumatic drive 59 controlled by the control unit 71 actuates the catching device 58 . As already shown, when a stopper is in operation, due to the high transport speed of several thousand sheets per hour transported in the conveying plane E19 of the suction belt table 19, z. B. of about 10,000 sheets per hour, and the relatively small gap of z. B. only about 20 mm between individual sheets directly following one another in their transport direction T is required to set up the 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 inject the sheets into the linear transport path, so that a transfer of further sheets fed to the suction belt table 19 after the at least one stop surface 66 of the catching device 58 has been raised to a curved, in particular arc-shaped 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 large force impact 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 in the use described and thus an operating life that is as unrestricted as possible.

How from the 8th 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 controls the movement of the cylinder piston 82 in such a way that a positive acceleration is generated for the cylinder piston 82 in a first half of its stroke and in a negative acceleration is set in the second half of its stroke following the first half. This pneumatic cylinder 81 has a bottom chamber 68 and a bearing chamber 69 which is separated from the bottom chamber 68 by the cylinder piston 82 , the cylinder piston 82 being firmly 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 acts on the crank 62 . The floor chamber 68 is arranged at that end of the pneumatic cylinder 81 which faces away from the pivot point G61, at which the drive 59 acts on the crank 62. The cylinder piston 82 preferably has an end position damping element 83; 84 on. The pneumatic circuit described in detail below is implemented by changing a dynamic pressure balance in the two chambers 68; 69 of the pneumatic cylinder 81 a controlled acceleration phase and a controlled braking phase over the entire stroke of the cylinder piston 82.

The pneumatic circuit has a first pneumatic switching valve 86 and a second pneumatic switching valve 87, both switching valves 86; 87 are each actuated by the control unit 71, preferably electrically. Both switching valves 86; 87 are each connected to their respective compressed air source 93 in one of their switching positions. 8th shows that 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 the catching device 58 is thus activated, which means that the stop surface 66 of the catching device 58 is set up in the conveying plane E19 of the suction belt table 19. At least the switching valve 86 for the bottom chamber 68 is preferably preceded by a pressure reducer 88 in order to build up a defined initial back pressure 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 bearing chamber 69 . In addition, the switching valve 86 of the bottom chamber 68 is followed by a throttle valve 91 in order to use this throttle valve 91, whose cross-section is preferably adjustable, to influence the outflow speed of the compressed air from the bottom chamber 68 and thus the dynamic pressure profile in the pneumatic cylinder 81 and thus the speed of the cylinder piston 82. It can e.g. 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 bottom chamber 68 and optionally the throttle valve 92 of the bearing chamber 69 are only when compressed air flows out of the respective chamber 68; 69 harnessed into the atmosphere.

Before the catching device 58 is activated, the bearing chamber 69 of the pneumatic cylinder 81 is preferably depressurized, i. H. there is a pressure z. B. 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 subjected to a pressure greater than the barometric pressure, e.g. B. with a pressure that corresponds to the pressure in the bottom chamber 68, so preferably with a pressure z. B. from 2 bar. If in both chambers 68; 69 set pressure is the same, the cylinder piston 82 is held in a stable end position. In the compressed air z. B. of 2 bar prestressed floor chamber 68 is provided via the pressure controllable air mass, which is required to brake the movement of the cylinder piston 82 occurring when the catching device 58 is activated. The activation of the catching device 58 with the shooting of its at least one stop surface 66 in a sheet gap between the trailing edge of a preceding sheet and the leading edge of a first subsequent sheet to be caught takes place in that the two switching valves 86; 87 can be actuated by the control unit 71, in particular simultaneously. As a result, the storage chamber 69 is from its compressed air source 93 with compressed air at more than 5 bar, in particular at a pressure of z. B. 7 bar and the air in the bottom chamber 68, which is prestressed at approx. 2 bar, can now escape into the atmosphere in a controlled manner via the throttle valve 91, whereby after a very short time a differential pressure of approx. 5 bar and thus a corresponding force on the cylinder piston 82 is present, which sets this cylinder piston 82 in motion. Controlled via the air mass trapped in the bearing chamber 69 and the opening cross section of the throttle valve 91, the braking effect begins in such a way that the movement of the cylinder piston 82 initially experiences a very high acceleration with the resulting speed, before this movement of the cylinder piston 82 is largely carried out by the actively clamped air column is braked and only a remaining residual speed of less than z. B. 10% of the previously achieved maximum speed at the end position damping element 83 of the pneumatic cylinder 81 is braked. When the catching 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 residual energy that is still present at the respective end position damping element 83; 84 to be dismantled. This very rapid movement of the cylinder piston 82 is transmitted in a greatly translated manner from the crank 62 to the coupling 63, which is preferably arranged in the central position of the sliding crank.

The described pneumatic circuit and the setting values for the pressure mentioned by way of example make it possible to bring the at least one stop surface 66 of the catching device 58 into a catching position through the already mentioned very narrow sheet gap, even at the already mentioned high transport speed of the sheets. Advantageously, high shock loads and peak loads are avoided by the solution shown in the entire kinematic system. Because the clamped air column, which dampens the drive movement of the cylinder piston 82 at the end, particularly in the bottom chamber 68, effectively prevents the cylinder bottom from being destroyed. In addition, a safe end position of the cylinder piston 82 in its retracted state is achieved without additional mechanical elements and thus without additional costs. The reduction in pressure in the storage chamber 69 also saves energy and reduces any leakage.

the 9 until 12 once again illustrate the dynamic in a diagram over the time t plotted on the abscissa Behavior of some physical variables with respect to the cylinder piston 82 of the pneumatic cylinder 81 during a switching process when the catching device 58 of the relevant suction belt table 19 is moved from its starting position to its catching position, in particular actuated by a control signal from the control unit 71. 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 z. B. shown with 10 mm. 10 shows an example of the speed v of the cylinder piston 82 during its movement along the travel z. 11 shows an example of the associated acceleration a, with which the cylinder piston 82 executes its movement along the adjustment path z. In the 12 the piston force F exerted by the cylinder piston 82 is then also shown as an example.

As described, there is a suction belt table 19 for horizontally transporting individual sheet-like substrates in a conveying plane E19, with the suction belt table 19 having a catching device 58 with at least one stop surface 66 for substrates to be caught, which is set up in its catching position in the conveying plane E19 of the suction belt table 19, with this at least a stop surface 66, starting from an inactive starting position of the catching device 58, is set up by a double-acting pneumatic cylinder 81 by a movement of its cylinder piston 82 into the catching position, this pneumatic cylinder 81 having a bottom chamber 68 and a bearing chamber 69 separated from the bottom chamber 68 by the cylinder piston 82 has, wherein a pneumatic circuit is provided for controlling the movement of the cylinder piston 82, the pneumatic circuit having a bottom chamber 68 connected to the first pneumatic switching valve 86 and a bearing chamber 69 connected to between eites pneumatic switching valve 87, both switching valves 86; 87 are each actuated by the control unit 71, preferably electrically. In this case, the catching device 58 has a crank mechanism driven by the cylinder piston 82 of the pneumatic cylinder 81 in accordance with the preceding description. The movement of the cylinder piston 82 is controlled by the control unit 71 such 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. At least the first switching valve 86 connected to the floor chamber 68 is preceded by a pressure reducer 88 . Also, at least the first switching valve 86 connected to the bottom chamber 68, e.g. B. a preferably adjustable in its opening cross-section throttle valve 91 downstream. The opening cross section of the throttle valve 91 z. B. adjusted 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, the residual speed of the cylinder piston 82 remaining at the end of the second half of its stroke at the relevant end position damping element 83; 84 is braked. In the inactive starting position of the catching device 58, at least the bottom chamber 68 of the pneumatic cylinder 81 is at a pressure greater than the barometric pressure, preferably at a pressure of z. B. 2 bar applied. To set the catching position of the catching device 58, the control unit 71 switches the first switching valve 86, which is connected to the bottom chamber 68, to a position that diverts the air mass from the bottom chamber 68 and at the same time switches the second switching valve 87, which is connected to the storage chamber 69, so that the storage chamber 69 is supplied with compressed air is subjected to a pressure of more than 5 bar.

In connection with the 2 It has been described that the suction belt table 19 has in its conveying plane E19 a switching area 52 with a plurality of suction bores 53 extending in the transport direction T of the sheets, with a plurality of suction chambers 41 preferably being arranged below the conveying plane E19 of the suction belt table 19, the flow effects of which can be controlled in each case. These suction chambers 41 are preferably arranged one behind the other in the transport direction T of the sheets and, in particular, their respective pressure is or at least can be switched individually and independently of one another. 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 arranged below the conveying plane E19 of the suction belt table 19, with the respective setting of the pressure in the relevant suction chamber 41 in this switching area 52 using a suction device 72 controlled by the control unit 71 at the suction bores 53 in the conveying plane E19 of the suction belt table 19, a negative pressure is set or at least adjustable. This negative pressure causes a sheet resting on the at least one feed belt 54 in the conveying plane E19 of the suction belt table 19 to be held in a frictional or non-positive manner. This is because the switching area 52 at least partially overlaps with the outline of the arc to be caught. The relevant feed belt 54 is z. B. is designed as an endlessly circulating suction belt, wherein a suction belt has at least partially a perforation, so that the at the suction holes 53 in the conveying plane E19 of the Suction belt table 19 set negative pressure can be effective through the feed belt 54 in question on the overlying sheet. The feed belt 54 is preferably designed as a flat belt or as a flat belt.

If a stopper operates and the at least one stop surface 66 of the catching device 58 is moved into its catching position, the frictional connection or frictional connection between the respective feed belt 54 and the sheet lying on it must be eliminated in a very short time, because otherwise the Sheets lying on the feed belt 54 are pushed together when they hit the at least one stop surface 66 of the catching device 58 that projects out of the conveying plane E19 of the suction belt table 19, i.e. H. would be crushed. Because at a transport speed of several thousand sheets per hour, z. B. of about 10,000 sheets per hour, it is not possible in the required short time in the suction chamber 41 in question the negative pressure set there by means of the suction device 72 controlled by the control unit 71 and thus the pressure acting on the sheets lying on the respective feed belt 54 nor to stop the feed belt 54 in question as such in good time before the sheet in question hits the at least one stop surface 66 of the catching device 58. In order to avoid damage to a sheet that is lying on the respective feed belt 54 when a stopper becomes operational and is the first to strike the at least one stop surface 66 of the catching device 58 that projects out of the conveying plane E19 of the suction belt table 19, there is therefore a need to reduce the aforementioned frictional connection or non-positive connection in comparison to switching off the suction device 72 of the suction chamber 41 in question and/or in comparison to stopping the feed belt 54 in question.

How from the 13 As can be seen, it is therefore proposed that at least one pneumatic timing valve 74 controlled by a control unit 71 is arranged in a supply line 73 that pneumatically connects the suction chamber 41 in question to the respective suction bores 53, the timing valve 74 in question providing the pneumatic connection when the catching device 58 is moved into its catching position interrupts. In a preferred embodiment, the clock valve 74 in question is designed in such a way 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 clock valve 74 in question and the respective suction bores 53 is supplied with barometric pressure or with a pressure which is 3% to 10% higher than barometric pressure, preferably 5% higher. The transport speed of the sheets corresponds to a cycle time in which directly successive sheets reach the position of the 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 cycle valve 74 in question is dimensioned to be shorter than the cycle time of sheets directly following one another and is preferably in a range between 20 ms and 100 ms, in particular 40 ms. The switching time of the clock valve 74 in question is the time beginning with the point in time of its actuation until reaching that point in time at which the clock valve 74 in question has stably changed from its first operating position into its second operating position. The control unit 71 is preferably designed in such a way that it puts the cycle valve 74 in question into the state that interrupts the pneumatic connection between the suction chamber 41 in question and the respective suction bores 53 one cycle time earlier before actuation of the catching device 58 .

The advantage of this solution found is that when a stopper is operating, the first sheet caught by the catch device 58 is not pushed together or crumpled. Rather, the arrangement of at least one clock valve 74, controlled by control unit 71, in supply line 73 between the suction chamber 41 in question and the respective suction bores 53 ensures that the process of catching prevents overrunning of the at least one feed belt 54 and / or a sustained suction of the relevant suction chamber 41 is independent.

As already mentioned in connection with the 1 until 3 explained, several sheets are fed to the suction belt table 19 by a transport device immediately upstream of the suction belt table 19, with these sheets lying individually at least in this transport device and on the suction belt table 19, each with a narrow gap between them, being transported one after the other along a linear transport path. In the preferred embodiment, these sheets are transported by means of several conveyor belts arranged one behind the other in the transport direction T of the sheets, starting with the circulating conveyor belt 18 of the transport device arranged immediately upstream of the suction belt table 19 via at least one transfer belt 44 belonging to the suction belt table 19, which, for example, B. as a preferably arranged in the central area of the conveying plane E19 of the suction belt table 19 circumferential flat belt is formed, in the transport direction T of the sheet after the transfer belt 44 z. B. two parallel ramps 48 z. B. are arranged in the form of circulating endless belts, followed by at least one in particular designed as a suction belt feed belt 54 and z. B. two parallel to each other arranged as a circulating endless belt brake bands 56. At each transition from a circulating endless belt - z. B. in 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 different machine unit, with 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 relevant conveyor belt in the transport direction T of the sheets consists in the conveying plane E19 of the sheets through a gap existing in this conveying plane E19 to a rotating deflection roller 76 of the relevant conveyor belt with a large width in relation to the thickness of the sheets in the area z. B. between 1 mm and 5 mm a point of discontinuity in the mechanical support of the sheets to be transported, this point of discontinuity just at a high transport speed of several thousand sheets per hour, z. B. of about 10,000 sheets per hour carries the risk of a breakdown. Because when transporting sheets lying on a circulating belt, there is a risk that the leading edge of the sheet in question at the end of the transport section given by the conveyor belt in question will be deflected into the relevant point of discontinuity due to its adhesion to the conveyor belt in question, which is deflected there at the end by means of deflection roller 76 , whereby such a sheet is prevented from being transported further and itself becomes an obstacle to subsequent sheets. This problem exists in particular in all transitions when at least one of the conveyor belts acting at the relevant transition is at least 25% of the width of the sheets to be transported, extending transversely to the transport direction T of the sheets. This is in the preferred embodiment z. B. also at the transition from the suction belt table 19 immediately upstream, z. B. belonging to a dryer 17 transport device to this suction belt table 19 is the case.

It is therefore proposed to replace the point of discontinuity in the mechanical support of the sheets to be transported in the conveying plane E19 with a pneumatic pressure force. This is done in that at the transition from the z. B. the suction belt table 19 immediately upstream transport device to this suction belt table 19 is arranged transversely to the transport direction T of the sheets extending guide device 42 with preferably a plurality of lifting nozzles 43 arranged in at least one row. This guide device 42 with its several lifting nozzles 43 is arranged in the transport direction T of the sheets in particular in front of the at least one skid belt 48 at the transition from the transport device arranged upstream of the suction belt table 19 to this suction belt table 19.

14 shows an example in a top view of a section of the z. B. in connection with the 3 Suction belt table 19 described. B. belonging to a dryer 17 circulating conveyor belt 18 lying in a conveying plane E19 transferred to the suction belt table 19. 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 that moves the conveyor belt 18 in the transport direction T of the sheets 77 and deflects it at the end of the transport device arranged directly 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 point of discontinuity 78 in their mechanical support located in the conveying plane E19. Transferred sheet 77 z. B. detected by a transfer belt 44 belonging to the suction belt table 19, this transfer belt 44 z. B. as a arranged in the central area of the conveying plane E19 of the suction belt table 19 circulating flat belt and / or as a suction belt. The transfer belt 44 follows in the transport direction T of the sheet 77 z. B. two parallel ramps 48 z. B. in the form of each encircling endless belts.

15 shows a schematic and highly simplified example of the guide device 42 arranged in a point of discontinuity 78 relating to the mechanical support of the sheets 77 to be transported, with at least one siphon nozzle 43, preferably with a plurality of siphon nozzles 43, this point of discontinuity 78 e.g. B. between a belonging to a non-impact printing device 13 circulating conveyor belt 16 and a belonging to a dryer 17 circulating conveyor belt 18 is arranged. A sheet 77 transported in the transport direction T tends, as a result of the rotation of the deflection roller 76, to extend with its front edge transversely to the transport direction T of the sheets 77 into a point located at the point of discontinuity 78 in the periphery of the deflection roller 76 being drawn into the gap and causing a malfunction. Such a point of discontinuity 78 in the mechanical support of the sheets 77 to be transported consists of a 1 exemplified sheet 77 lying transporting digital printing machine at several positions, z. B. 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.

the 16 until 19 explain the mode of operation of the guide device 42 arranged in such a point of discontinuity 78 with respect 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 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, preferably designed as a digital printing machine.

16 shows the initial situation for the function of the guide device 42 arranged in the point of discontinuity 78. B. 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 tapered profile element 79 extending transversely to the transport direction T of the sheets 77, preferably in the form of a profile element a squeegee, the tip of this profile element 79 preferably being arranged approximately tangentially opposite to 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 deflected by the transport belt 16 of the Non-impact printing device 13 is spaced apart by a gap, this gap having a greater width in relation to the thickness of the sheets 77 in the range z. B. between 1 mm and 5 mm. In the profile element 79 at least one opening in the direction of its tip siphon nozzle 43 is arranged, through which siphon nozzle 43 at a z. B. controlled by the control unit 71 activation of the guide device 42 in the 17 indicated by a directional arrow is directed or at least can be directed against the conveyor belt 16 of the non-impact printing device 13, which is deflected at the deflection roller 76. In the state of in the 17 When the guide device 42 is activated, the sheet 77 lying on the conveyor belt 16 of the non-impact printing device 13 has changed due to the rotation of the deflection roller 76 compared to that in FIG 16 illustrated initial situation increasingly approaches the gap formed into the guide device 42, with the front edge of the relevant sheet 77 continuing to follow the curvature of the deflection roller 76 in a manner potentially provoking an operational disruption.

How from the 18 and 19 As can be seen, the air jet blown out of the at least one lifting nozzle 43 arranged in the profile element 79 when the guide device 42 is activated flows against the conveyor belt 16 of the non-impact printing device 13, which is deflected at the deflection roller 76. This air jet hits the conveyor belt 16 in this way that the direction of the core jet of this air jet intersects the circular peripheral 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 limit of this air jet facing the front edge of the relevant sheet 77 neither intersects nor exceeds a tangent between the peripheral line of the deflection roller 76 and the relevant 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 front edge of the relevant 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 relevant sheet 77 from the conveyor belt 16 of the non-impact printing device 13 ( 18 ) and as the deflection roller 76 continues to rotate, the leading edge of the sheet 77 in question is increasingly lifted off the conveyor belt 16 of the non-impact printing device 13 due to a back pressure that arises ( 19 ), so that the front edge of the sheet 77, which is still largely lying 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 as it is transported further.

After the leading edge of the relevant sheet 77 rests securely on the profile element 79, the guide device 42 z. B. preferably deactivated by the control unit 71 by the air jet flowing out of the at least one siphon nozzle 43 being switched off. The air jet flowing out of the at least one lifting nozzle 43 is therefore preferably active in a clocked manner, with this clock being synchronized with the arrival of the front edge of the respective sheet 77 at the deflection roller 76 of the conveyor belt 16 deflected by means of this deflection roller 76. A from the at least one siphon nozzle 43 of the guide device 42 flowing out The air jet is therefore preferably only maintained until the front edge of the respective sheet 77 has passed the gap located in the periphery of the deflection roller 76 and extends transversely to the transport direction T of the sheets 77 at the point of discontinuity 78 and the front edge of the respective sheet 77 has contacted the profile element 79 of the guide device 42 has been lifted.

This results in a machine arrangement with a plurality of processing stations that each process sheets 77, with these processing stations being arranged one behind the other in the transport direction T of the sheets 77, with at least one of these processing stations having a first transport device transporting the sheets 77 along a linear transport path with at least one on a rotating deflection roller 76 deflected, endlessly revolving conveyor belt 16, this first transport device being designed to be transported in a sequence in immediate succession, each lying on its at least one conveyor belt 16, with this processing station having the first transport device transporting the sheets 77 also on at least one endlessly revolving conveyor belt 18 lying downstream along a linear transport path transporting second transport device or a suction belt table 19, where at the point transfer of the sheets 77 to be transported from the conveyor belt 16 of the first transport device either to the conveyor belt 18 of the second transport device following in the transport direction T of the sheets 77 or to the suction belt table 19 in a conveying plane E19 of these sheets 77 to be transported, in each case a point of discontinuity 78 in the mechanical support of each sheet 77 to be transferred, the deflection roller 76 that deflects the at least one conveyor belt 16 of the first transport device being arranged at the point of discontinuity 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 has a profile element 79 tapering to a point, is arranged at this point of discontinuity 78, with the tip of this profile element 79 being directed counter to the transport direction T of the sheets 77 towards the transport belt 16 of the first transport device, with at least one siphon nozzle 43 is arranged on the profile element 79, the relevant siphon nozzle 43 being designed to open in the direction of the tip of this profile element 79. The tip of the profile element 79 is spaced from the deflected on the rotating deflection roller 76 conveyor belt 16 of the first transport device by a gap, this gap having a greater width in relation to the thickness of the sheet 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 . At a z. B. activation of the guide device 42 controlled by a control unit 71, an air jet flowing out of the mouth of the respective lifting nozzle 43 is directed or at least can be directed against the conveyor belt 16 of the first transport device, which is deflected at the deflection roller 76, with this air jet being directed onto the conveyor belt 16 in such a way that that a core jet of this air jet intersects the peripheral line of the deflection roller 76 as a secant. The air jet in question is also aligned in particular in such a way that a free upper limit of this air jet, facing a front edge of a sheet 77 being transported on conveyor belt 16 of the first transport device, does not intersect a tangent between the peripheral line of deflection roller 76 and the relevant lifting nozzle 43 of guide device 42 still exceeds. The control device 42 is activated by the control unit 71 .

The control unit 71 activates the guide device 42 z. B. clocked, this cycle is synchronized with the arrival of the front edge of the respective sheet 77 at the deflection roller 76 of the deflected by means of this deflection roller 76 conveyor belt 16 of the first transport device. The guide device 42 is therefore preferably designed to maintain the air jet flowing out of the relevant siphon nozzle 43 only until the front edge of the respective sheet 77 passes the gap at the point of discontinuity 78 that is located in the periphery of the deflection roller 76 and extends transversely to the transport direction T of the sheets 77 and the front 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 . The deflection roller 76 that 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 at the top. Since the machine arrangement is designed as a digital printing machine in its preferred embodiment, 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.

When passing through a z. B. by hot air and / or by IR radiation drying dryer 17 are applied on a conveyor belt 18 individually flat lying previously in a non-impact printing device 13 printed sheet with a very high heat input, resulting in The result is that these dried sheets are deformed, ie bulge in particular, and as a result at least partially lose their flatness. A bulging of the dried sheets can take on 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 the correct position. As a result, arched sheets provided at the outlet of the dryer 17 can be transported by a transfer belt 44 of a transport device immediately downstream of the dryer 17 in the transport direction T of the sheets, the z. B. belongs to a suction belt table 19 or to a cooling section, can no longer be reliably accepted due to inadequate detection, which in a machine arrangement having several transport devices very quickly leads to a malfunction, particularly if such sheets are transported at a transport speed of several thousand sheets per hour, e.g. B. of about 10,000 sheets per hour follow one another. The reason for the inadequate detection of the arched sheets is, in particular, that the bending resistance forces inherent in the curvature of the sheets in question cannot be overcome by a height-dependent suction force exerted by a suction belt. This problem of the unreliable takeover of sheets that are bulged in their edge region, 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 kink 46; 47 occur at which a curvature of the previously z. B. horizontal conveying plane is formed ( 2 and 3 ). However, in order to avoid damage to a printed image previously applied in the non-impact printing device 13 on the upper side of the sheet in question, it is not advisable to force arched sheets from above to lie flat at the points mentioned in the machine arrangement described here, e.g. B. by means of a mechanical hold-down device.

In order to create the necessary frictional or non-positive connection from a sheet that is arched up, in particular as a result of heat input, to a suction belt and to transport this sheet with the suction belt in the correct position, it is proposed that the physical phenomenon of the aerodynamic paradox, in particular with regard to the lateral edge areas of a highly arched front edge of one of a sheet to be taken over by a suction belt and/or a sheet to be transported by a suction belt.

The solution found is explained using the previously described suction belt table 19 as an example. 20 shows an enlarged section of the in the 3 Suction belt table 19 shown in a top view, this section focusing in particular on an arrangement of nozzles 49 in an area between one of the two skimming belts 48 arranged parallel to one another in the transport direction T of the sheets and a conveyor plane E19 of the suction belt table running longitudinally to the transport direction T of the sheets 19 laterally delimiting edge 94 relates. The ramp belts 48, like 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 in the form of a suction belt, with the suction belt in question being in an operative pneumatic connection with a suction device 72 and, as a result of its at least sectional perforation can exert a suction force on an overlying sheet. The transport direction T of the sheets is in the 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 flow emerging from these nozzles 49, is z. B. directed in the transport direction T of the sheets. In a preferred and in the 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 inclined by 45° in the transport direction T of the sheets to the edge 94 laterally delimiting the conveying plane E19 of the suction belt table 19. It can advantageously also be provided that the blowing direction of a first subset of the nozzles 49 z. B. orthogonal 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 z. B. by 45 ° in the transport direction T of the sheet to which the conveying plane E19 of the suction belt table 19 laterally bounding edge 94 is inclined.

21 shows an excerpt from the in the 2 illustrated side view of the suction belt table 19. It is provided that the suction belt table 19, in particular from a dryer 17, is fed to at least one transfer belt 44 and transported further in the conveying plane E19 of the suction belt table 19. Particularly in the area of the at least one transfer belt 44 and in the area of the chute 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 following a point of discontinuity 78 in the mechanical support of the sheets to be transported, e.g . B. 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, several nozzles 49 are arranged ( 3 and 20 ). This 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 controlling 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 z. B. controlled by the control unit 71 clock valve 74 is arranged. Such a clock 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 precise moment when the front edge of a sheet to be transported is covered by the relevant nozzle 49. The application 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 brought into overlap by a nozzle 49 closest in the transport direction T of the sheets. It is also provided that the application of compressed air to the nozzles 49 arranged in the outline of a sheet to be caught is then interrupted by means of the relevant timing valve 74 when the catching device 58 of the suction belt table 19 is switched to its catching position.

This results in a suction belt table 19 with at least one endlessly circulating take-over belt 44 designed as a suction belt for taking over sheets transported individually lying flat on 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, with the suction belt table 19 in of its conveying plane E19 has an arrangement of a plurality of nozzles 49, 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, with these nozzles 49 each being designed as Venturi nozzles , wherein a flow direction of at least a first subset of the nozzles 49 arranged in said area is directed in the transport direction T of the sheets and/or wherein a flow direction of at least a second subset of those arranged in said area Nozzles 49 are 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 the named area is at 45° to the transport direction T of the sheets to which the conveying plane E19 of the Suction belt table 19 laterally bounding edge 94 is directed inclined. In addition, at least one bend 46; 47 be formed, with each of these kinks 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, with the in the area between the at least one transfer belt 44 and the relevant conveying plane E19 the arrangement of the nozzles 49 formed on the edge 94 delimiting the suction belt table 19 in the transport direction T of the sheets over the relevant bend 46; 47 extends beyond. In the area mentioned or in the areas following one another in the transport direction T of the sheets, the nozzles 49 are each z. B. arranged in several rows extending transversely to the transport direction T of the sheets ( 3 and 20 ).

The nozzles 49 are each connected to a compressed air source 93 by means of a pneumatically connecting feed line 96, with at least one of the feed lines 96 connecting at least one of the nozzles 49 to the compressed air source 93 preferably having a control valve 97 for adjusting and/or controlling the pressure of one of the respective nozzle 49 outflowing air flow is arranged. In a preferred embodiment, a clock valve 74 is arranged in the feed line 96 in question that connects at least one of the nozzles 49 to the compressed air source 93 between the control valve 97 in question and the nozzle 49 in question. The control valve 97 in question and/or the clock valve 74 in question are controlled by a control unit 71 . The clock valve 74 in question is activated by the control unit 71 in particular when the leading edge of a sheet to be transported is overlapped by the nozzle 49 in question. The clock valve 74 in question is deactivated by the control unit 71 in particular when the front edge of the sheet to be transported in question is brought into overlap by a nozzle 49 that is closest in the transport direction T of the sheets. In a particularly preferred embodiment, the suction belt table 19 has a catching device 58 with the features described above for sheets to be caught, the clock valve 74 in question being deactivated by the control unit 71 when the catching device 58 is switched to its catching position.

Since the nozzles 49 are each designed as a Venturi nozzle, they produce a suction force on a sheet to be transported that is many times greater than one Holding force generated by the suction flow on a suction belt arranged in the conveying plane E19 of the suction belt table 19, which is provided to hold a sheet lying flat on the relevant suction belt. In addition, the width of the region that has the arrangement of nozzles 49, extending transversely to the transport direction T of the sheets, is designed to be significantly larger than the width of the relevant suction belt, which extends transversely to the transport direction T of the sheets, so that the width of the suction belt outside the width of the relevant suction belt the arrangement of the area having nozzles 49 is in a substantially more favorable relationship to the width of the arched leading edge of the relevant sheet. Consequently, an effective surface formed by the arrangement of the nozzles 49 and acting on the arched front edge of the sheet in question is significantly larger than the effective surface acting on the arched front edge of the sheet in question by the suction belt in question. However, the larger the respective effective area, the easier it is to overcome the bending resistance forces inherent in the curvature of the arch in question. Since the effect of the suction flow of the suction belt in question is dependent on the height and decreases more and more 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 arched front edge of the sheet in question to be sucked forward until the the leading edge in question reaches the effective area of the suction flow of the suction belt in question. After the arched front edge of the sheet in question is located sufficiently deep in the effective range of the suction flow of the suction belt in question due to the effect of the nozzles 49, this suction flow may be strong enough to push the arched front edge of the sheet in question over the remaining residual height to the suction belt in question to suck and to produce the frictional connection or frictional connection required for a positionally accurate transport of the sheet in question. In a preferred embodiment, control unit 71 is thus designed in such a way that it first applies compressed air to nozzles 49 and only then, i.e. with a delay, does the suction force exerted on the sheet by at least one transfer belt 44 designed as a suction belt begin to act.

Reference List

01

sheet feeder

02

first stack

03

suction head

04

first swing grab

05

first coating device

06

transport cylinder

07

printing unit cylinder

08

application roller

09

squeegee; chamber doctor blade system

10

-

11

first gripper system

12

conveyor belt

13

Non-impact printing facility

14

first dryer

15

-

16

conveyor belt

17

second dryer

18

transport device; conveyor belt

19

suction belt table

20

-

21

second swing grab

22

second coating device

23

transport cylinder

24

printing unit cylinder

25

-

26

application roller

27

squeegee; chamber doctor blade system

28

second gripper system

29

display

30

-

31

third dryer

32

second stack

33

transfer drum

34

transfer drum

35

-

36

front stamp

37

blow box

38

bulkhead

39

opening

40

-

41

suction chamber

42

control device

43

siphon nozzle

44

transfer belt

45

-

46

first kink

47

second kink

48

ski jump tape

49

jet

50

-

51

catchblower

52

switching range

53

suction hole

54

infeed conveyor

55

-

56

brake band

57

suction roll

58

capture device

59

drive

60

-

61

piston rod

62

crank

63

paddock

64

Rail

65

-

66

stop surface

67

opening

68

attic chamber

69

storage chamber

70

-

71

control unit

72

suction device

73

supply line

74

timing valve

75

-

76

deflection roller

77

bow

78

point of discontinuity

79

profile element

80

-

81

pneumatic cylinder

82

cylinder piston

83

End position cushioning element

84

End position cushioning element

85

-

86

first pneumatic switching valve

87

second pneumatic switching valve

88

pressure reducer

89

pressure reducer

90

-

91

throttle valve

92

throttle valve

93

compressed air source

94

edge

95

-

96

supply line

97

control valve

a

acceleration

f

piston force

i

transmission ratio

M

centerline

t

time

T

transport direction

v

speed

e.g

travel

A51

Distance

B19

Broad

D62

pivot point

E1

end point

E2

end point

E19

funding level

G61

pivot point

G62

pivot point

G63

Straight

G64

Straight

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102016207397 A1 [0005, 0011]

Claims (14)

Suction belt table (19) for sheet-shaped substrates to be transported lying individually, the suction belt table (19) being arranged between a transport device arranged upstream in the transport direction (T) of the substrates and a correspondingly arranged downstream transport device, characterized in that the suction belt table (19) has a catching device (58 ) with a catching position assumed as a result of an actuation for individual substrates that follow one another in a sequence, with the catching device (58) in its catching position feeding the substrates supplied to the suction belt table (19) by the upstream transport device before a respective transfer to the one downstream of the suction belt table (19). Transport device catches on the suction belt table (19). Suction belt table (19) after claim 1 , characterized in that the transport device arranged upstream of the suction belt table (19) has a translatory transport path for the sheet-shaped substrates to be transported lying individually and/or in that the transport device arranged downstream of the suction belt table (19) has a rotary transport path or a translatory transport path for the sheet-shaped substrates to be transported having. Suction belt table (19) after claim 1 or 2 , characterized in that a control unit (71) is provided, this control unit (71) actuating the catching device (58) as a function of a disruption that has occurred along the transport route belonging to the transport device downstream of the suction belt table (19) in such a way that the catching device ( 58) takes up her catch position. Suction belt table (19) after claim 1 or 2 or 3 , characterized in that the catching device (58) has at least one pivotable stop surface (66) for substrates to be caught, the relevant stop surface (66) being arranged below a conveying plane (E19) of the suction belt table (19) when the catching device (58) is not actuated and when the catching device (58) is actuated, it is pivoted through an opening (67) in the conveying plane (E19) of the suction belt table (19) and positioned perpendicular to this conveying plane (E19), so that substrates transported on the suction belt table (19) are held against the push at least one raised stop surface (66) protruding from the conveying plane (E19) of the suction belt table (19). Suction belt table (19) after claim 1 or 2 or 3 , characterized in that the catching device (58) has a slider-crank mechanism, the slider-crank mechanism having a link (63) and a crank (62) interacting with the link (63), the crank (62) being driven by a drive (59). is. Suction belt table (19) after claim 5 , characterized in that the crank (62) is rotatably mounted in a pivot point (D62) arranged in a stationary manner in the suction belt table (19), the crank (62) being designed as an angled lever and having a short lever and a short lever compared to this has a longer lever, the short lever connecting a pivot point (G61), on which the drive (59) acts on the crank (62), to the pivot point (D62) of the crank (62), the longer lever of the crank ( 62) between its pivot point (D62) and a pivot point (G62) at which the crank (62) is connected to the coupling (63), the short lever and the longer lever of the crank (62) having a length ratio to one another such are such that they accelerate a movement acting on the coupler (63) from the drive (59) of the catching device (58). Suction belt table (19) after claim 6 , characterized in that the speed-up ratio is at least 1:5. Suction belt table (19) after claim 4 or 5 or 6 or 7 , characterized in that an end point (E2) of the coupler (63) facing away from the drive (59) of the catching device (58) can be moved linearly and bidirectionally along a path (64) arranged parallel to the conveying plane (E19) of the suction belt table (19), wherein the end point (E2) of the coupler (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 them, with this straight line (G64) runs parallel to the conveying plane (E19) of the suction belt table (19). Suction belt table (19) after claim 4 or 5 or 6 or 7 or 8th , characterized in that the at least one stop surface (66) for substrates to be caught is in a region between an end point (E1) of the coupler (63) facing the drive (59) of the catching device (58) and the pivot point (G62) at which the crank (62) is connected to the coupler (63). Suction belt table (19) after claim 4 or 5 or 6 or 7 or 8th or 9 , characterized in that the at least one stop surface (66) for substrates to be caught is formed from a plastic, in particular from a polyamide or from a polyoxymethylene. Suction belt table (19) after claim 5 or 6 or 7 or 8th or 9 or 10 , characterized in that the slider crank mechanism has a central slider crank, in which the three routes G62-D62; G62-E2; G62-E1 are each of the same length and the end points (E1; E2) of the coupler (63) together with the articulation point (G62) arranged between them are all on a straight line (G63) connecting the end points (E1; E2) of the coupler (63) with one another are arranged. Suction belt table (19) after claim 5 or 6 or 7 or 8th or 9 or 10 or 11 , characterized in that the drive (59) is designed as a double-acting pneumatic cylinder (81), this pneumatic cylinder (81) having a bottom chamber (68) and one separated from the bottom chamber (68) by a cylinder piston which is firmly connected to its piston rod (61). (82) has a separate storage chamber (69), a first pneumatic switching valve (86) being connected to the bottom chamber (68) and a second pneumatic switching valve (87) being connected to the storage chamber (69), these two switching valves (86; 87) are each controlled by the control unit (71) of the catching device (58). Suction belt table (19) after claim 12 , characterized in that the bottom chamber (68) has barometric pressure or that the bottom chamber (68) has a differential pressure greater than the barometric pressure and less than the pressure in the storage chamber (69). Suction belt table (19) after Claim 13 , characterized in that the piston rod (61) of the pneumatic cylinder (81) is retracted by pressurizing the bearing chamber (69) with at least 5 bar, preferably with 7 bar and/or that the cylinder piston (82) of the pneumatic cylinder (81) is retracted the piston rod (61) of the pneumatic cylinder (81) works against compressed air preloaded at 2 bar in the bottom chamber (68).

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