Drying device in a printing press and printing press with this drying device

Abstract

Drying device (01) in a printing press, wherein the drying device (01) is designed to dry a surface of a substrate (02) printed and / or varnished by the printing press by applying both infrared radiation and hot air, wherein the drying device (01) has on its side facing the surface of the substrate (02) to be dried a guide surface (03) spaced apart from the surface of the substrate (02) with a plurality of nozzles (04), wherein each of these nozzles (04) has an opening cross-section through which, or at least through which, hot air flows, and wherein the hot air flowing onto the surface of the substrate (02) flows out through a gap opening formed between the guide surface (03) and the surface of the substrate (02), wherein the area of ​​the gap opening,The area of ​​the opening through which the hot air flowing onto the surface of the substrate (02) flows out is smaller than the total area of ​​all the opening cross-sections of the hot air directed onto the surface of the substrate (02) of the nozzles (04), wherein the ratio of the area of ​​the opening through which the hot air flowing onto the surface of the substrate (02) flows out to the total area of ​​all the opening cross-sections of the hot air directed onto the surface of the substrate (02) is less than 0.7, wherein this drying device (01) has several drying modules (49) arranged in series in the transport direction (T) of the substrate (02), wherein at least one infrared radiation source (06) directed onto the surface of the substrate (02) to be dried is arranged between adjacent drying modules (49).wherein the drying module (49) in question has a blow box (51) and the guide surface (03) which delimits the blow box in question (51) in the direction of the surface of the substrate (02) to be dried, wherein a blower (52) and an air guide grille (53) are arranged as a heating register above the guide surface (03) and wherein the drying module (49) in question has a meandering jet catcher (59) in the flow path between the blower (52) and the air guide grille (53).

Description

[0001] The invention relates to a drying device in a printing press and a printing press with this drying device.

[0002] US Patent 2010 / 0 192 792 A1 discloses a printing machine comprising: a printhead configured to produce ink on a printing surface, wherein the ink contains at least one element; a dryer configured operationally to dry the ink applied to the printing surface, the dryer being in fluid communication with an exhaust stream to remove the at least one element; at least one sensor operationally connected to the dryer's exhaust stream, the at least one sensor being configured to i) determine a flow rate of the at least one element present in the exhaust stream and / or ii) determine a moisture content of the exhaust stream and / or iii) determine a temperature of the exhaust stream and / or iv) identify the at least one element;and a control system in operative connection with the at least one sensor and the dryer, wherein the control system comprises at least one program for determining a degree of ink dryness detected on the printing surface, based on a comparison of the at least one element of the exhaust gas stream and either i) the at least one element present in the ink before the ink dries on the printing surface or ii) the at least one element present in the ink after the ink dries on the printing surface or iii) a predetermined value for the at least one element.

[0003] DE 93 13 212 U1 discloses a device for guiding an elongated web of material through a space of a plant which is limited in height, comprising a holding element for gripping the insertion end of the web of material.

[0004] EP 2 463 100 A1 discloses a sheet-fed processing machine, in particular a sheet-fed printing press, with a coating unit and one or more combination dryers, wherein the combination dryers subject the freshly coated sheet to both radiant energy and heated air, the combination dryers containing a plurality of round or polygonal air nozzles, between which narrowband high-power infrared light sources are arranged, from which the coated sheet is irradiated with a total radiant density of at least 25 kW / m² 2 is capable of being actuated, wherein the temperature of the heated air passing through the nozzles is below 100°C, preferably below 80°C.

[0005] JP 2015 - 155 091 A discloses a drying device with a drying module, wherein the drying module has a blow box and a guide surface limiting the blow box towards the surface of the substrate to be dried, wherein a blower and an air guide grid are arranged as a heating register above the guide surface.

[0006] A drying device is known from JP H07 - 186 368 A, wherein a gap in the form of an annular gap is formed between a guide surface of the drying device and a conveyor belt of a transport device which transports the substrate to be dried along a drying section through the drying device, wherein this gap has a gap width of up to 30 mm.

[0007] DE 10 2016 207 397 A1 discloses a sheet-fed printing machine with a sheet-fed dryer printed by a non-impact printing device.

[0008] The US 2021 / 0 146 680 A1 shows a low-temperature, high-speed air dryer.

[0009] The invention is based on the objective of creating a drying device in a printing press with improved efficiency, as well as a printing press with this drying device.

[0010] The problem is solved according to the invention by the features of claims 1 and 4. The dependent claims each describe advantageous embodiments and / or Further training on the solution found.

[0011] The advantages achievable with the invention consist in particular of improved efficiency of a printing press dryer. The increased efficiency according to the invention makes it possible to shorten the drying time required by the dryer for drying substrate printed in the printing press, thus enabling faster production with the printing press or reducing the energy input required for the drying process. Further advantages are evident from the following description.

[0012] Exemplary embodiments of the invention are shown in the drawings and are described in more detail below.

[0013] They show: Fig. 1 a drying module of a drying system; Fig. 2 a drying module of the drying device with integrated channels; Fig. 3 different cross-sectional areas of infrared radiation sources; Fig. 4 different arrangements of infrared radiation sources; Fig. 5 different designs for integrating the infrared radiation sources into the drying system; Fig. 6 a sheet-fed printing press with a drying device according to Fig. 1 or Fig. 2; Fig. 7 a side view of the drying device with several drying modules arranged in a row; Fig. 8 one of the drying modules in an enlarged section from the Fig. 7; Fig. 9 a drying module with an integrated infrared radiation source; Fig. 10 a drying module with a beam catcher; Fig. 11 a first arrangement of nozzles in a guide surface of a drying module; Fig. 12 a second arrangement of nozzles in a guide surface of a drying module; Fig. 13 A bottom view of several drying modules arranged in a row.

[0014] In a printing press in which a sheet-shaped or web-shaped substrate moved through the printing press at a transport speed must be dried by means of a drying process after the application of a printed image and / or a varnish layer with a water-soluble printing ink and / or a water-soluble varnish before its placement or further processing, a drying device is arranged above and along the transport path of the substrate, wherein the drying device exposes a printed and / or varnished surface of the substrate to be dried with infrared radiation and / or hot air.While the infrared radiation heats the printed and / or varnished surface of the substrate to be dried, and thus also the air in a boundary layer located directly above this surface, the hot air has two functions: firstly, to further heat the surface of the substrate, and secondly, to remove the humid air in the boundary layer directly above the surface of the substrate, which is enriched with water vapor and thus caused by the evaporation of the water in the printing ink and / or varnish by the heat input, and to replace it with new dry hot air emitted by the drying device.

[0015] However, the drying unit's effect on the printed and / or varnished surface of the moving substrate is limited both by its duration and by the fact that the heat input cannot be increased indefinitely. This is because, firstly, the dwell time of the moving substrate in the drying unit is finite due to the length of the drying section and the given transport speed of the substrate. Secondly, the substrate must not become too hot, because exceeding a maximum permissible stacking temperature, for example, in the delivery of the printing press, poses a risk of the stacked substrates, especially sheet-shaped ones, becoming stuck together. Furthermore, temperatures higher than those actually required for drying the substrate will subsequently lead to condensation.Because the liquid components of the printed ink evaporate from a hot substrate and then condense on cold components of the drying unit or printing press. If a hot substrate is varnished after a drying process carried out at an excessively high temperature, the intended gloss levels decrease with the substrate temperature, resulting in a reduction in print quality.

[0016] Furthermore, increasing the volume flow and / or temperature of the hot air is not economically viable. Increasing the temperature of the hot air, for example, places additional stress on all components and / or parts of the printing press located in the immediate and / or downstream vicinity of the drying unit. This can lead to problems such as lubricants decomposing and / or leaking from their point of use, and / or exceeding the maximum permissible temperature of components such as sensors, electrical components, and / or plastic parts, potentially impairing or even disabling their function. Additionally, further thermal stress may necessitate design modifications to the printing press components, for example, by...On traversing components, a loose bearing must be provided on one side due to expected thermal expansion.

[0017] The solution proposed here essentially adds pressure as a further state variable to the convection flow used by the drying unit for the drying process, which already transports heat and jet momentum. This pressure from the convection flow significantly increases the flow velocity at which the hot air passes over the printed and / or varnished surface of the substrate being dried, thereby increasing the effectiveness and efficiency of the drying unit.

[0018] As can be seen from a schematic representation in the Fig. As can be seen in Figure 1, the drying device 01, preferably arranged in a printing press, is designed in the form of at least one drying module. The drying module in question has, on its side facing the surface of the, for example, sheet-shaped substrate 02 to be dried and moved by the printing press in the transport direction T, a guide surface 03 extending over, for example, a linear drying section, with a plurality of nozzles 04. Each of these nozzles 04 has an opening cross-section through which, or at least through which, hot air flows. In particular, an edge of a sheet-shaped substrate 02 that is raised from its flat position can be guided along the drying section through the drying device 01 on the guide surface 03 of the drying device 01. In, for example,In a digital printing press designed as a sheet-fed printing press for printing and / or coating a sheet-shaped substrate 02, the drying section of the drying device 01 is preferably flat and linear, whereas in a rotary printing press for printing and / or coating a sheet-shaped or web-shaped substrate 02, the drying section of the drying device 01 is preferably designed as a curved web. While a sheet-shaped substrate 02 is preferably transported lying on conveyor belts along the flat conveying section, sheet-shaped or web-shaped substrates 02 are preferably transported lying on cylinders along the curved conveying sections of a rotary printing press. Specifically for sheet-fed rotary printing presses, these cylinders are equipped with gripper bars for capturing the sheet edges for sheet transport.

[0019] For one in the Fig. 1 and Fig. The jet formation of the hot air flowing from the nozzles 04, indicated by directional arrows, can be achieved by using different nozzles 04 with differently shaped opening cross-sections, as required and / or simultaneously. The aim is to scrape off the moist air in the boundary layer immediately above the surface of the substrate 02 to be dried, i.e., to remove it as much as possible, or at least to swirl it around, thus ensuring air exchange at the surface of the substrate 02. The nozzles 04, arranged in or on the guide surface 03, are designed, for example, as round nozzles, slot nozzles, or Venturi nozzles.

[0020] Suitable radiation sources for the infrared radiation emitted by the drying device 01 include, for example, infrared emitters with a heating coil arranged in a glass tube or infrared halogen emitters with a heating coil arranged in a glass tube filled with halogen. Surface emitters with heating elements arranged over a flat area are also suitable. The cross-sectional area of ​​such infrared radiation sources 06 is, for example, in the form of a circle, an oval, a twin tube, a square, or a trapezoid, as exemplified by the Fig. Figure 3 shows different representations of the cross-sectional area. Fig. Figure 4 shows examples of different arrangements of the infrared radiation sources 06. For example, the infrared radiation sources 06 can be arranged in the guide surface 03 transversely, longitudinally or obliquely to the transport direction T of the moving printing material 02 or in the form of tiles. Fig. Figure 5 shows two different designs for integrating the infrared radiation sources 06 into the respective drying module of the drying device 01. In the Fig. 5. In the schematically depicted embodiment a), at least part of the conductive surface 03 of the drying device 01 is, for example, made of glass and thus transmissive to infrared radiation, so that the infrared radiation emitted by the infrared radiation sources 06, indicated by directional arrows, can penetrate the conductive surface 03 of the drying device 01 in the direction of the surface of the substrate 02 to be dried. In the Fig. In the schematically depicted embodiment b), at least part of the guide surface 03 of the drying device 01 is made of a metallic material, e.g., a sheet, and is therefore impermeable to infrared radiation. This means that the guide surface 03 of the drying device 01 has openings through which the infrared radiation emitted by the infrared radiation sources 06, indicated by directional arrows, can radiate towards the surface of the substrate 02 to be dried. In this second embodiment, it is important that the openings are narrow and that the leading edge of the opening is further away from the conveyor belt than the trailing edge. This prevents a convex sheet leading edge, which slides along the guide surface 03, from catching on the leading edge of the opening.

[0021] To prevent air stagnation, the hot air flowing onto the surface of the moving substrate 02 flows out through a gap opening formed between the guide surface 03 of the drying device 01 and the surface of the substrate 02, this gap opening being formed, for example, in the form of an annular gap.

[0022] Additionally, channels 07 with a preferably circular cross-section can also be incorporated into the drying module of the drying device 01 ( Fig. 2) through which the moist air in the boundary layer immediately above the surface of the substrate 02 to be dried is partially extracted. The channels 07 for the partial extraction of the moist air in the boundary layer immediately above the surface of the substrate 02 to be dried are arranged in the guide surface 03 of the drying device 01, preferably in its edge regions running parallel to the transport direction T of the moving substrate 02, which also has a positive effect on the correct orientation of the moving substrate 02 along the drying path of the drying device 01.

[0023] The drying process, which is caused by the radiant energy emitted by infrared radiation sources 06 primarily heating the surface of the substrate 02, but also, to a lesser extent, heating its deeper layers, is significantly supported by the gap flow according to the invention. This is because, firstly, a considerably larger volume flow of heated hot air is provided directly at the surface of the substrate 02 to be dried, and secondly, the heat and moisture exchange between the moist surface of the substrate 02 to be dried and the gap flow is promoted by the convection, which is enhanced by the physical state variable pressure and thus velocity. Therefore, the drying device 01 becomes more efficient while maintaining all energy input parameters.

[0024] The invention is described below by way of example in the context of a digital printing machine designed as a sheet-fed printing machine, i.e., printing on a substrate 02 designed as a sheet, which has several machine units arranged one after the other in the transport direction T of the sheets, wherein at least one of these machine units has a transport device that transports the sheets along a linear transport path. This transport device is preferably designed as at least one conveyor belt on which the sheets are transported one after the other. While lying on the at least one conveyor belt, the individual sheets are held to the respective conveyor belt by a suction force, i.e., by a holding force caused by a suction flow, in a frictional or force-fit manner. The suction force is typicallyThis is achieved by a vacuum applied to each sheet, adjusted relative to the surrounding barometric air pressure by means of a suction device. Such a transport device is arranged in the sheet-fed printing press exemplified here, at least in the machine unit that includes the drying device 01 described above. The drying device 01 is thus designed, in particular, as a continuous dryer for single-layer sheets. In a preferred embodiment, a cooling device for cooling and / or conditioning the sheets heated in the drying device 01 follows the drying device 01. A suction belt table, for example, is arranged downstream of the cooling device.

[0025] Fig. Figure 6 shows an example of such a sheet-fed printing press. Viewed in the transport direction T of the sheets, the sheet-fed printing press first has a sheet feeder 11 in which a first stack 12 of sheets is ready for processing. The sheets are preferably rectangular substrates made of paper, cardboard, or corrugated board. Paper, cardboard, and corrugated board differ in their respective basis weight, i.e., the weight in grams per square meter of these sheets. Paper has a basis weight between 30 g / m². 2 and 150 g / m² 2 Cardboard has a basis weight between 150 g / m² 2 and 600 g / m² 2 and cardboard with a basis weight of more than 600 g / m² 2 The sheets can also each be a substrate made of a plastic and / or be designed as a thin sheet. The sheet feeder 11 can also be designed as a magazine feeder comprising several first stacks 12.

[0026] A sheet separator 13, also referred to as a suction head, grasps each of the stacked sheets successively from above and feeds these sheets, e.g., by means of a first vibrating gripper 14 and optionally a transfer drum 44 cooperating with the first vibrating gripper 14, in a sequence of separated sheets to, e.g., a first coating unit 15, wherein this first coating unit 15 is designed, e.g., as a primer application unit. The first coating unit 15 has, e.g., a transport cylinder 16 designed as a printing cylinder and, e.g.,A printing cylinder 17, cooperating with this transport cylinder 16, has an application roller 18 attached to or at least adjustable against this printing cylinder 17, preferably in the form of an anilox roller, wherein at least one doctor blade 19 or a chambered doctor blade system 19 extends in the axial direction of the application roller 18 for optimal metering of a coating material to be applied to the surface of the sheets. The transport cylinder 16 transports the sheets held on its outer surface along a curved, in particular arc-shaped, transport path. The first coating device 15 applies the coating material, e.g., a primer, to one of the two sides of the sheets either completely or only at certain, i.e., previously determined, locations. The sheets are then transferred from the transport cylinder 16 to the first coating device 15, e.g.,by means of a preferably continuously circulating first gripper system 21, in particular a first chain conveyor, and e.g. at least one first conveyor belt 22, the sheets are transferred to a non-impact printing device 23, wherein the first gripper system 21 and the first conveyor belt 22 cooperate when transferring the sheets to the non-impact printing device 23, such that the first gripper system 21 delivers the sheets to the first conveyor belt 22, which has a linear transport section, and the sheets are transferred to the non-impact printing device 23 from the first conveyor belt 22. The first conveyor belt 22 is preferably designed as a continuously circulating endless belt. In an advantageous embodiment, a first dryer 24 is provided in the area of ​​the first gripper system 21 for drying the sheets coated in the first coating device 15, wherein this dryer 24 is, for example,is designed as a hot air dryer and / or as a dryer that dries using IR radiation or UV radiation.

[0027] The non-impact printing unit 23 typically comprises several, e.g., four, independently controllable inkjet printing units, each of which applies a different printing color to the side of the sheet previously coated, e.g., in the first coating unit 15, to create a preferably multi-colored printed image. In the sheet-fed printing press described here as an example, the non-impact printing unit 23 preferably includes a second conveyor belt 26, so that the sheets are printed by the inkjet printing units while resting on this second conveyor belt 26. The second conveyor belt 26 is preferably designed as a continuous, circulating belt.In the transport direction T of the sheets, a second dryer 27 is arranged downstream of the non-impact printing device 23 for drying the printed sheets. This second dryer 27 is configured as a hot air dryer and as a dryer drying by IR radiation. The second dryer 27 has a transport device 28 which transports the sheets horizontally in a translational manner, i.e., along a linear transport path. This transport device 28 is located in the Fig. In the sheet-fed printing press shown as an example in Figure 6, a third conveyor belt 28 is configured. This third conveyor belt 28 is also preferably configured as a continuous, circulating belt. The transport device 28 of the second dryer 27 in this example transfers the dried sheets preferably to a suction belt table 29, from which the sheets are transferred, for example, by means of a second vibrating gripper 31 and optionally a transfer drum 43 cooperating with the second vibrating gripper 31, to a second coating device 32. The second coating device 32 is configured, for example, as a coating device, wherein this second coating device 32 applies a coating material, e.g., a varnish, in particular to a printed image previously created in the non-impact printing device 23. The second coating device 32 again has, for example, a transport device for sheets to be transported.A transport cylinder 33 designed as a printing cylinder, wherein, for example, a printing cylinder 34 interacts with this transport cylinder 33 and an application roller 36, preferably in the form of an anilox roller, is attached to or at least attachable to this printing cylinder 34, and wherein at least one doctor blade 37 or a chambered doctor blade system 37 extends in the axial direction of the application roller 36. The first transport belt 22 and / or the second transport belt 26 and / or the third transport belt 28 are each preferably designed as a circulating flat belt and, moreover, preferably as a suction belt, wherein the suction belt has a perforation at least in sections.

[0028] The sheets are then transported from the transport cylinder 33 of the second coating unit 32, e.g., by means of a preferably continuously rotating second gripper system 38, in particular a second chain conveyor, to a delivery unit 39, wherein the sheets processed in this exemplary sheet-fed printing press described are placed by the second gripper system 38 in the delivery unit 39, preferably in a second stack 42. In an advantageous embodiment, a third dryer 41 is provided in the area of ​​the second gripper system 38 for drying the sheets coated in the second coating unit 32, wherein this third dryer 41 is designed, e.g., as a hot air dryer and / or as a dryer drying by IR radiation or by UV radiation. The delivery unit 39 can also be designed as a multi-stack delivery unit comprising several second stacks 42. The previously described process in conjunction with the Fig. The drying device 01 described in 1 to 5 can each be arranged in the first dryer 24 drying the sheets coated in the first coating device 15, or in the second dryer 27 drying the sheets printed by the non-impact printing device 23, or in the third dryer 41 drying the sheets coated in the second coating device 32.

[0029] The one in Fig. Figure 6, an exemplary digital printing press, is designed for use in an industrial printing process, particularly for the mass production of printed materials. This sheet-fed printing press sequentially feeds individual sheets from the sheet feeder 11 to the delivery 39 at a transport speed of several thousand sheets per hour, e.g., approximately 10,000 sheets per hour. Along at least one of the linear transport paths, adjacent sheets in their transport direction T, i.e., sheets that follow directly one another in the sequence, are separated from each other by a gap. This gap is significantly smaller than the sheet length extending in the transport direction T and is only a few millimeters, e.g., approximately 20 mm.

[0030] During a pass through a dryer 27 that dries using hot air and / or IR radiation, sheets previously printed in a non-impact printing unit 23, lying flat on a conveyor belt 28, are subjected to a very high heat input. This causes the dried sheets to deform, i.e., to curl, and thus lose their flatness on the conveyor belt 28, at least partially. The curling of the dried sheets can reach such an extent that the sheet loses its adhesion to the conveyor belt 28 of the dryer 27 and, if the conveyor belt 28 is designed as a suction belt, can no longer be held by the suction force exerted on it. Consequently, the sheet is no longer transported in a oriented position.Furthermore, curled sheets provided at the dryer 27 outlet can no longer be reliably picked up by a transport device downstream of the dryer 27 in the sheet transport direction T, e.g., by the transport device of a cooling unit 46 or a suction belt table 29, due to inadequate gripping. In the aforementioned sheet-fed printing press, which has several transport devices, this leads very quickly to an operational disruption, especially when such sheets follow one another at a transport speed of several thousand sheets per hour, e.g., at a transport speed in the range between 2,500 and 10,000 sheets per hour. The reason for the inadequate gripping of the curled sheets lies particularly in the fact that the bending resistance forces inherent in the curling of the sheets in question cannot be overcome by a height-dependent suction force exerted by a suction belt. Therefore, as in the... Fig. Figure 6 shows a cooling unit 46 immediately downstream of the dryer 27 in the transport direction T of the sheets. This cooling unit 46 is either integrated into the frame of the dryer 27 or designed as an independent machine unit in a separate frame. At the outlet of the cooling unit 46, the sheets, heated to more than 80°C in the dryer 27, are cooled to, for example, 30°C. There are at least four reasons for using the cooling unit 46: a) to reduce heat-induced deformation of the sheets; b) to reduce condensation caused by moisture evaporating from the sheets and condensing on the relatively cold surfaces of components of the dryer 27 and / or the printing press; c) to reduce the heating of downstream components connected to the dryer 27 caused by hot sheets; d) a cold sheet results in more gloss points during subsequent varnishing after the printing process.

[0031] Again Fig. The cooling device 46, located above a conveying level E in which sheets are conveyed flat through the cooling device 46, has at least one cooling module 47, preferably several cooling modules 47 arranged in series along, for example, a linear conveying path. The conveyor belt 28 of the dryer 27 also extends, for example, through the cooling device 46. However, it is more advantageous for the drying section defined by the dryer 27 and the cooling section defined by the cooling device 46 to each have separate conveyor belts. This is because the conveyor belt in the drying section should be hot so that the sheet is also heated by the conveyor belt and thus dries better. In the cooling section, the conveyor belt should be cold so that the sheet is additionally cooled by its contact with the conveyor belt.

[0032] The cooling module 47 is preferably designed to use air as a coolant, e.g., ambient air or cooled air. Alternatively or additionally to the cooling module 47, the transport device of the cooling device 46, which transports the sheets to be cooled, may have transport rollers 48, wherein these transport rollers 48 are actively cooled by a roller cooling system using, for example, water as a cooling medium.

[0033] Fig. Figure 7 shows an exemplary side view of the drying device 01 arranged in at least one of the dryers 24; 27; 41, wherein this drying device 01 has several drying modules 49 arranged in series along, for example, a linear transport path. These drying modules 49 are each arranged close together, for example, above the transport device 28 of the dryer 27, which is designed as an endlessly circulating conveyor belt and is directly downstream of the non-impact printing device 23 in the transport direction T of the substrate 02.

[0034] Fig. Figure 8 shows an enlarged section from the Fig. 7 a single drying module 49 arranged in the drying device 01. Each of the drying modules 49 has, above a guide surface 03, a blower box 51 and, in particular, a heat-resistant blower 52 and an air guide grille 53 as a heating element, wherein the heating element is used to heat the air set in motion by the blower 52. The substrate 02, e.g., designed as a sheet, is guided in a gap 54 extending between the guide surface 03 of the drying device 01 and the conveyor belt 28 of the transport device of the dryer 27, wherein transport rollers 48 supporting the conveyor belt 28 are arranged below the conveyor belt 28 of the transport device of the dryer 27. The gap 54, which is in particular designed as an annular gap, has a gap width S between, e.g., 8 mm and 35 mm, preferably between 10 mm and 20 mm. In the Fig. In the embodiment shown in section 8, a separation joint 56 is formed between drying modules 49 arranged adjacent to one another in the transport direction T of the printing material 02, each with at least one on the

[0035] An infrared radiation source 06 directed towards the surface of the substrate 02 to be dried is arranged. The infrared radiation source 06 is covered, for example, with a protective glass 57 on its side facing the surface of the substrate 02 to be dried, in particular to guide a curved, i.e., raised, edge of the curved substrate 02.

[0036] Fig. Figure 9 shows an alternative embodiment of the drying modules 49, in which the respective infrared radiation source 06, directed towards the surface of the substrate 02 to be dried, is integrated into the housing 58 of the respective drying module 49. Otherwise, this is located in the Fig. The illustrated version of the drying modules 49 is comparable to that shown in the Fig. The 8 versions shown and described are identical in construction.

[0037] Fig. 10 shows further training of the previously in the Fig. 8 or Fig. 9 drying modules 49 shown, wherein in this further development the drying module 49 in question has a jet catcher 59 in the flow path between the blower 52 and the air guide grid 53, in particular a meandering shape, so that the blower 52 and the air guide grid 53 are thermally decoupled.

[0038] As already described, a plurality of nozzles 04 are arranged in the guide surface 03 that delimits the blow box 51 of the drying module 49 in the direction of the surface of the substrate 02 to be dried, these nozzles 04 being able to have differently shaped opening cross-sections. A portion of these nozzles 04 are shown in an exemplary illustration in the Fig. 11 e.g., each designed as a round nozzle 61 or as a Venturi nozzle 62. An arrangement of these nozzles 04 in the guide surface 03 is preferably symmetrical to a center line M running longitudinally to the transport direction T of the substrate 02 to be dried. The round nozzles 61 pressurize a large part of the volume flow onto the surface of the substrate 02 to be dried, while the Venturi nozzles 62, which preferably blow largely towards the lateral edges of the substrate 02, ensure a defined removal of the moistened air. The increase in the moisture content of the air as it flows from the inside to the outside is compensated for by an increase in the volume flow of dry air from the nozzles 04 located further out.

[0039] Fig. Figure 12 shows an exemplary arrangement of the nozzles 04 in the guide surface 03, in which the nozzle density decreases from the inside, i.e., starting from the center line M, on both sides towards the outside, i.e., towards the lateral edges 63 of the guide surface 03, thereby limiting the required total volume flow. A prerequisite for this arrangement of the nozzles 04 is that the amount of air flowing through the gap 54 from the inside to the outside is not yet saturated up to the gap exit and can absorb moisture up to the respective edge 63 of the guide surface 03.

[0040] Fig.Figure 13 shows a bottom view of several drying modules 49 arranged in a row along a drying section. Each, for example, rectangular guide surface 03 of the blowing boxes 51 alternates in the transport direction T of the substrate 02 to be dried with at least one protective glass 57 of the infrared radiation sources 06, extending transversely to the transport direction T of the substrate 02 to be dried, and for example in the form of a rectangular strip. The respective guide surface 03 of the blowing boxes 51 and the respective protective glass 57 of the infrared radiation sources 06 preferably lie in the same plane extending along the drying section, so that a particularly stiff substrate 02 can be guided through the respective drying device 01 without any steps, i.e., without tripping hazards, even if the edge is curved out of the flat position.Furthermore, combining the partial areas of the involved guide surfaces 03 and protective glasses 57 with respect to the entire drying device 01 favors the formation of only a small annular gap, so that the ratio of the annular gap area to the nozzle opening cross-sections 04 is very favorable, namely less than one, preferably less than 0.7. This consequently results in a higher overpressure being imposed on the gap flow than would occur with a ratio of the annular gap area to the nozzle opening cross-sections 04 greater than one. Reference symbol list 01 Drying device 02 Printing material 03 Guide surface 04 Nozzle 05 - 06 Infrared radiation source Channel 7 08 - 09 - 10 - 11 arch feeders 12 first pile 13 sheet separators 14 first swing gripper 15 first coating equipment 16 transport cylinders 17 printing cylinders 18 Application roller 19 doctor blades; chamber doctor blade system 20 - 21 first gripper system 22 conveyor belt 23 Non-Impact Printing Device 24 first dryer 25 - 26 conveyor belt 27 second dryer 28 Transport equipment; conveyor belt 29 Suction belt table 30 - 31 second swing gripper 32 second coating unit 33 transport cylinders 34 printing cylinders 35 - 36 Application roller 37. Doctor blades; chambered doctor blade system 38 second gripper system 39 Display 40 - 41 third dryer 42 second stack 43 Transfer drum 44 Transfer drum 45 - 46 Cooling unit 47 Cooling module 48 Transport roller 49 Drying module 50 - 51 blowboxes 52 blowers 53 air guide grilles 54 gap 55 - 56 Separation joint 57 Protective glass 58 cases 59 beam catchers 60 - 61 Round nozzle 62 Venturi nozzle 63 Rand E funding level M Center line S gap width T Transport direction

Claims

[1] Drying device (01) in a printing press, wherein the drying device (01) is designed to dry a surface of a substrate (02) printed and / or varnished by the printing press by applying both infrared radiation and hot air, wherein the drying device (01) has on its side facing the surface of the substrate (02) to be dried a guide surface (03) spaced apart from the surface of the substrate (02) with a plurality of nozzles (04), wherein each of these nozzles (04) has an opening cross-section through which, or at least through which, hot air flows, and wherein the hot air flowing onto the surface of the substrate (02) flows out through a gap opening formed between the guide surface (03) and the surface of the substrate (02), wherein the area of ​​the gap opening,The area of ​​the opening through which the hot air flowing onto the surface of the substrate (02) flows out is smaller than the total area of ​​all the opening cross-sections of the hot air directed onto the surface of the substrate (02) of the nozzles (04), wherein the ratio of the area of ​​the opening through which the hot air flowing onto the surface of the substrate (02) flows out to the total area of ​​all the opening cross-sections of the hot air directed onto the surface of the substrate (02) is less than 0.7, wherein this drying device (01) has several drying modules (49) arranged in series in the transport direction (T) of the substrate (02), wherein at least one infrared radiation source (06) directed onto the surface of the substrate (02) to be dried is arranged between adjacent drying modules (49).wherein the drying module (49) in question has a blow box (51) and the guide surface (03) which delimits the blow box in question (51) in the direction of the surface of the substrate (02) to be dried, wherein a blower (52) and an air guide grille (53) are arranged as a heating register above the guide surface (03) and wherein the drying module (49) in question has a meandering jet catcher (59) in the flow path between the blower (52) and the air guide grille (53). [2] Drying device (01) according to claim 1, characterized by, that the infrared radiation source (06) directed towards the surface of the substrate (02) to be dried is covered on its side facing the surface of the substrate (02) to be dried with a protective glass (57) and / or that the respective infrared radiation source (06) directed towards the surface of the substrate (02) to be dried is integrated into the housing (58) of the drying module (49) in question. [3] Drying device (01) according to claim 1 or 2, characterized by , that a gap (54) in the form of an annular gap is formed between the guide surface (03) of the drying device (01) and a conveyor belt (28) of a transport device which transports the substrate (02) to be dried along a drying section through the drying device (01), wherein this gap (54) has a gap width (S) between 8 mm and 35 mm, preferably between 10 mm and 20 mm. [4] Printing press with a drying device (01) according to one of the preceding claims. [5] Printing press according to claim 4, characterized by , that the printing machine is designed as a sheet-fed printing machine, wherein the sheet-fed printing machine is designed as a digital printing machine. [6] Printing press according to claim 4 or 5, characterized by , that the drying device (01) is arranged in a dryer (27) arranged in the transport direction (T) of the substrate (02) immediately after a non-impact printing device (23).

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