Corrugated board plant, methods for operating a corrugated board plant and methods for converting a corrugated board plant

Abstract

The invention relates to a corrugated board machine (2) extending in a longitudinal direction (L) from a back side (4) to a front side (6), which has a wet end (8) beginning at the back side (4) and a dry end (10) ending at the front side (6), which is configured for producing corrugated board from several paper webs (12, 12a) and which includes a printer (28) for printing on one of the paper webs (12), so that this is then a printed paper web (12a) with a printed side (30), which includes a drying section (32) for the printed paper web (12a), wherein the drying section (32) begins at the printer (28). The invention further relates to a method for operating a corrugated board machine (2) and a method for converting an existing corrugated board machine into a corrugated board machine (2).

Description

[0001] The invention relates to a corrugated board plant, a method for operating such a corrugated board plant and a method for converting a corrugated board plant.

[0002] A corrugator is used to produce corrugated board. Several paper webs are unwound from a respective unwinder and joined together to form a single corrugated board web. For this purpose, one of the paper webs is typically corrugated with a fluting roller and then glued to two non-corrugated paper webs. Multi-layer corrugated board webs with more than one corrugated paper web are also possible. The finished corrugated board web can optionally be cut into individual pieces by the corrugator. It is also advantageous to integrate a printer into the corrugator to print the paper webs as needed and depending on the order.

[0003] Corrugated board systems with an integrated printer have the problem that the print image on the paper web that was printed using the printer must dry sufficiently before the printed paper web can be processed further. For example, a single paper web is printed within the corrugator and then joined to other paper webs in a double-facer to form the corrugated board web. To do this, the paper web must pass through a preheater and a gluing unit and is generally in contact with corresponding rollers at various times. If the print image is not sufficiently dried during further processing of the printed paper web, the print image will smear. This not only reduces the quality of the print image, but also potentially contaminates system stations in the corrugator and their individual components, e.g. rollers, with ink.

[0004] In principle, it is possible to design the print image and the production process of the corrugated board web in such a way that smearing does not occur on a given corrugator. For example, a small amount of ink is printed, which then dries quickly, or the conveying speed through the corrugator is reduced accordingly, allowing more time for drying before further processing. However, this results in limitations on the performance and flexibility of the corrugator.

[0005] Against this background, it is an object of the present invention to provide an improved corrugated board system that is as flexible and efficient as possible. The corrugated board system should be able to process as many different jobs as possible at the maximum possible speed. To this end, the drying of the printed image on the printed paper web should be improved in particular in order to be able to print images with a large amount of ink applied without subsequent smearing and to be able to operate the corrugated board system at the highest possible conveying speed. Furthermore, a correspondingly suitable method for operating such a corrugated board system and a method for converting a corrugated board system should be specified.

[0006] The object is achieved by a corrugated board plant having the features according to claim 1, a method having the features according to claim 14, and a method having the features according to claim 15. Advantageous embodiments, further developments, and variants are the subject of the dependent claims. The statements made in connection with the corrugated board plant also apply mutatis mutandis to the two methods, and vice versa. If one or more steps of a method (in particular the method for operation) are implicitly or explicitly stated below, suitable embodiments for the corrugated board plant result from the fact that it is designed to carry out one or more of these steps.

[0007] A key aspect of the present invention is, in particular, a drying section that is as long as possible directly downstream of a printer in a corrugator. This makes it possible to achieve sufficient drying even with high conveying speeds and heavy ink application and to avoid the aforementioned disadvantages of incomplete drying. A particularly important aspect is to integrate this drying section as optimally as possible into a system layout for a corrugator. Firstly, as little additional space as possible should be required; limitations on the overall size of the corrugator are typically imposed by the surrounding dimensions (e.g., the length or height of a factory hall). Secondly, retrofitting existing corrugator systems should be as inexpensive as possible.Existing system layouts are typically optimized for minimal installation space, making it difficult to add additional system stations, especially a printer and a subsequent drying section. Third, the drying section should be as accessible as possible, especially to make threading the printed paper web as easy as possible. This is especially important when switching from a job without printing to one with printing and vice versa.

[0008] The corrugated board plant according to the invention extends in a longitudinal direction from a back side to a front side. The corrugated board plant has a wet end, which begins at the back side, and a dry end, which ends at the front side. The back side is thus a beginning of the corrugated board plant and the front side correspondingly its end. The corrugated board plant is designed to produce corrugated board from multiple paper webs. The paper webs are each unwound from an unwind unit, conveyed through the corrugated board plant and processed in the process. Each unwind unit is a station of the corrugated board plant. In the wet end, the paper webs are assembled to form the corrugated board web. For this purpose, the corrugated board plant has in particular one or more single facers, a preheater, a gluing unit and a double facer.In the dry end, which begins downstream of the double-facer, the corrugated board web is finished as needed using suitable system stations. The exact configuration of the dry end is not important in this case. The longitudinal direction corresponds to a general conveying direction through the corrugator, meaning that the paper webs and the corrugated board web are generally conveyed in a longitudinal direction, but are locally deflected as needed using appropriate deflection elements.

[0009] In the context of the present application, the terms "front / in front of / in front of" and similar terms as well as "back / behind / behind" and similar terms are understood spatially and relative to the longitudinal direction, i.e. "front" and similar terms mean in the direction of the front and "back" and similar terms mean in the direction of the rear. In other words: a component A of the corrugator is located behind a component B of the corrugator if component A is closer to the rear than component B. This means that component A is located behind component B when viewed opposite to the longitudinal direction. The same applies to "in front of". The longitudinal direction points from the rear to the front; the opposite direction is accordingly referred to as "opposite the longitudinal direction". The terms "below / below / below" and similar terms as well as "above / above / above" and similar terms are to be understood as directional indications perpendicular to the longitudinal direction and perpendicular to a support surface (e.g.Floor level) on which the corrugator is installed. A component A of the corrugator is located above a component B of the corrugator if component A is further away from the installation area than component B, but in particular both components are positioned at least at a similar longitudinal position when viewed in the longitudinal direction. The same applies to "below" and similar. The terms "upstream" and "downstream", however, are understood relative to a respective paper web or relative to the corrugator web. In other words: a component A of the corrugator is located downstream of a component B of the corrugator if one of the paper webs first passes through component B and then component A. Component A can be located in front of or behind component B, i.e. the paper web is guided from component B to component A either in the longitudinal direction or against the longitudinal direction.The reverse applies to the term "upstream." Components A and B are, for example, system stations of the corrugator or individual components thereof. The above statements also apply to the description of the figures below.

[0010] The corrugator has a printer for printing on one of the paper webs so that this then becomes a printed paper web with one printed side. During printing, ink is printed on one side of the paper web, namely the side that is then printed, thereby creating a print image. This side is then the printed side, while the other, opposite side of the paper web typically remains unprinted. The printer is one of several stations in the corrugator. The printer is preferably an inkjet printer. The printer is preferably a monochrome printer, i.e. it only prints a single color. An inkjet printer and a monochrome printer are particularly compact. However, a monochrome printer is not essential; in principle, a printer with multiple colors can also be used.

[0011] The corrugated board line also has a drying section for the printed paper web. The paper web that is printed with the printer is then conveyed through the drying section, so that the printed paper web dries along the drying section; this occurs in particular before further processing in another system station and in any case before the printed side comes into contact with a component of a system station. For this purpose, the mere additional residence time created by the drying section (passive drying) is typically sufficient. Optionally, the corrugated board line has a system station arranged along the drying section for treating, handling, or inspecting the paper web. For example, the drying section has a drying unit as a system station for additional drying of the printed paper web (active drying).For this purpose, the drying unit includes, for example, one or more IR emitters, contact surface heaters, and / or hot air dryers. The drying unit is optionally used to precondition the printed paper web for further processing in the corrugator, e.g., to achieve a specific shrinkage.

[0012] The drying section is also referred to as the penetration section because drying is characterized by the ink penetrating the paper web. Ink that does not penetrate the paper web (incomplete drying) potentially leads to smearing of the print image downstream of the printer.

[0013] The drying section begins at the printer (more precisely, at one of the printer's print heads). This makes the drying section as compact as possible. The drying section includes a detour for the printed paper web on its further path through the corrugator, particularly on its way to the next station.

[0014] The drying section preferably has a reverse section which leads towards the back side, so that the printed paper web is guided on the reverse section against the longitudinal direction. This is also referred to as reverse guidance. The printed paper web is therefore not guided downstream of the printer in the general conveying direction (longitudinal direction) to the next system station, but first in the opposite direction, namely backwards, i.e. against the longitudinal direction and behind the printer. This creates a particularly long drying section. A key aspect in particular is the reverse guidance of the printed paper web, which takes place along the reverse section, because this creates additional installation space within the corrugator, which enables the drying section to be extended.

[0015] Alternatively or in addition to the reverse guide, in an advantageous embodiment the drying section has a vertical section which leads upwards or downwards with respect to the longitudinal direction, i.e. in particular perpendicularly or generally at an angle greater than 0° to the longitudinal direction, wherein the angle is preferably at least 60° (vertical direction). This is then referred to as “vertical guide” in the same way as the reverse guide. Here too the printed paper web downstream of the printer is initially not guided in the general conveying direction (longitudinal direction) to the next system station, but in a vertical direction, i.e. upwards or downwards. This also creates an advantageously long drying section. The vertical guide particularly uses installation space in front of or behind the printer for an extended drying section.Instead of simply passing the paper web from the printer, at least the height of the printer is used as a drying section.

[0016] The reverse guide and the vertical guide are generally also referred to as detour guides. What is particularly important here is that the paper web downstream of the printer is not guided as directly as possible to the next system station, but via a detour, namely the reverse section and / or the vertical section of the drying section. The drying section therefore contains a detour for the printed paper web and does not lead directly to the next system station. A design in which the drying section has both a reverse section and a vertical section is also particularly useful. A design in which the reverse section adjoins the vertical section is particularly useful, so that the paper web is first output from the printer, then guided upwards or downwards (preferably: upwards) and then backwards.A combination of several vertical sections and / or several backward sections is also possible.

[0017] The printed paper web is output by the printer in particular in the longitudinal direction, i.e. towards the front, i.e. to the front. From here, the printed paper web is then deflected first upwards (or downwards) by means of a suitable (first) deflection element, and then towards the back, i.e. to the rear, by means of a (second) deflection element. The second deflection element marks an end of the vertical section and also a beginning of the reverse section and, in particular, has no contact with the printed side, but only with the opposite, unprinted side (as does the first deflection element). Alternatively, the printed paper web is output by the printer directly against the longitudinal direction, i.e. to the rear. The reverse section then begins directly at the printer or its print head; alternatively or additionally, a vertical section is passed through as described.Regardless of the direction in which the printer outputs the printed paper web, the drying section also has an end, which is marked by a (third) deflection element, with which the printed paper web is deflected again, in particular back to the front. This third deflection element is in particular in contact with the printed side. The return section also ends at this third deflection element. From the printer to the end of the return section, the printed side, however, remains untouched and has the appropriate time (dwell time) to dry up to this point.

[0018] The aforementioned deflection elements preferably have one or more deflection rollers for deflecting the printed paper web. In an advantageous embodiment, one or more deflection elements are heated, so that the printed paper web is additionally heated and thus dried by the respective deflection element.

[0019] In a preferred embodiment, the drying section is defined by beginning at a print head of the printer and ending at a deflection element of the corrugator, and by leaving the printed side untouched between the print head and the deflection element. Instead, only the non-printed side is touched—if necessary. Also advantageous is a configuration in which the deflection element that first comes into contact with the printed side downstream of the printer has a special non-stick coating that reduces the adhesion of the ink to the deflection element (compared to a deflection element without such a non-stick coating).

[0020] The drying section is generally located downstream of the printer and, due to the reverse section, preferably guides the printed paper web behind the printer. The next station (e.g., a preheater) of the corrugator is located downstream of the drying section. The "next station" is understood to mean that there is no further station between it and the drying section. The next station is preferably located upstream of the printer, or alternatively, behind it.

[0021] Without limiting its generality, the following assumes a design in which the printer is arranged upstream of an unwind unit of the corrugator and downstream of a preheater of the corrugator. No further system stations are arranged between the unwind unit and printer, or between the printer and preheater. A paper web is unwound using the unwind unit, which is fed to the printer and printed there. The now printed paper web is then fed via the drying section to the preheater. The unwind unit, the printer, and the preheater are arranged in particular on a common assembly level, but the drying section is on a different assembly level, in particular on an assembly level above the printer and optionally also above the unwind unit.Depending on the specific design of the corrugator and the printer's location within it, alternative arrangements to the preferred arrangement described above may also be suitable. For example, the printer is located at the rear of the corrugator, e.g., behind or above the unwinding unit closest to the rear.

[0022] Downstream of the preheater, the paper webs are fed into a gluing unit of the corrugator. The preheater serves to precondition the paper webs before glue is applied in the gluing unit. While still in the gluing unit or downstream of it, the paper webs are then pressed together to form the corrugated board web and fed into a heating section (i.e. the double facer). The point at which the paper webs are pressed together to form the corrugated board web is also referred to as the gluing point. Similarly, the point at which ink is printed onto the paper web in the printer is referred to as the printing point. The printing point is fundamentally defined by the printer's print head. The entire drying section, or at least the reverse section, is preferably located above an imaginary connecting line between the printing point and the gluing point.

[0023] By guiding the paper web backwards with the reverse section and guiding it in the vertical direction with the vertical section, the path for the printed paper web to the next system station is extended. In principle, a certain drying distance is already automatically created by the fact that the printed paper web has to travel a certain distance from the printer to the next system station of the corrugator. However, since a system layout that is as compact as possible is typically chosen, the printer is usually positioned as close to the next system station so that the path in between is as short as possible and is only suitable to a limited extent as a drying path. In the sense of the invention described here, the drying path is therefore deliberately extended by means of a detour, resulting in a longer drying path (penetration path).While the next station is still conveniently positioned as close as possible to the printer, the drying section is not the shortest possible route from the printer to the next station. Rather, the drying section described here deliberately creates a detour for the printed paper web, namely a detour up / down and / or back, to achieve the longest possible drying section. This correspondingly extends the dwell time until further processing of the printed paper web.

[0024] The reverse section is preferably at least 0.5 m long (measured along the paper web), more preferably at least 5 m, and particularly preferably at least 10 m long. This only describes the length of the reverse section in one direction; the entire drying section, measured along the paper web, is usually longer. Specifying an upper limit for the length of the reverse section is not necessarily useful; however, it is typically sufficient if the reverse section is at most 20 m long, thus corresponding to approximately 1 / 5 to 1 / 10 of the total length of the corrugator.

[0025] In an advantageous embodiment, the drying section is further extended by being folded, with several sections on which the paper web is guided alternately towards the back (to the rear) and towards the front (to the front). Those sections on which the paper web is guided towards the back then each form a backward section, as already described. The remaining sections are analogously referred to as forward sections. Depending on the design, this results in a spiral or meandering course of the paper web along the drying section. For example, the printed paper web is output from the printer to the front with the print image facing downwards and, downstream of the printer, is initially guided along a first backward section towards the back using a deflection element which acts on the non-printed side.The printed paper web is then deflected along a first forward section back towards the front side by means of another deflection element, which also acts on the non-printed side. This concept can in principle be repeated several times depending on the available installation space, so that the paper web alternates through several backward sections and, if necessary, several forward sections. In this case, each deflection element only ever acts on the non-printed side. Finally, however, the printed paper web must be guided to the next system station by means of at least one final deflection element, which then marks the end of the drying section. This final deflection element then inevitably acts on the printed side of the paper web.

[0026] The corrugator, in particular, has a bridge. The bridge serves to temporarily store semi-finished products for the corrugated board web, namely products from one or more single-facers, each of which produces a corrugated paper web and joins it to a non-corrugated, flat paper web to form a so-called half-wave. The bridge is arranged, in particular, in an assembly plane above the assembly plane of the printer.

[0027] In a preferred embodiment, the printer is arranged below the bridge. The printer is used in particular for printing a so-called laminating web, i.e. the paper web which is then subsequently assembled with one or more half-flutes to form the corrugated board web and then forms an outer layer of the corrugated board web. Accordingly, the unwinding unit, which feeds the paper web to the printer, is also arranged below the bridge. The return section is expediently arranged within the bridge or in a space between the printer and the bridge. This allows the drying section to be integrated into the corrugator in a particularly space-saving manner. This also avoids the drying section requiring additional installation space in the assembly plane of the printer, so that the printer and the system stations in front of and behind it (e.g. unwinding unit and preheater) are positioned particularly close to the printer.The overall length of the corrugator is not affected by this. Rather, the drying section, especially its reverse section, is placed on an assembly level above the printer. This assembly level either corresponds to the assembly level of the bridge, so that the reverse section is located within the bridge, or an additional assembly level for the reverse section is inserted between the printer and the bridge, particularly by raising the bridge accordingly. This increases the height of the corrugator, but not its overall length.

[0028] The bridge expediently has a catwalk from which the reverse section is accessible, in particular for manually threading the printed paper web into the reverse section. The catwalk runs in particular laterally along the bridge in the longitudinal direction. The catwalk originally serves in particular as access to the bridge in order to be able to carry out maintenance or the like on it if necessary. Advantageously, the reverse section is now also accessible from the catwalk, in particular both are on the same level. This then makes it easy to thread the printed paper web into the reverse section from the catwalk. This is particularly relevant in designs in which the printer has a height that is greater than a person, e.g. 2 m to 2.5 m, so that threading from the mounting level (floor level) of the printer is difficult.

[0029] The corrugated board machine suitably includes a splicer. The splicer is, in particular, part of an unwinding unit, which also includes two unwinders. A paper web is alternately unwound from the unwinders, and the splicer joins the end of one paper web to the beginning of the other during a roll change. In a suitable embodiment, the splicer is arranged above the two unwinders.

[0030] In an advantageous embodiment, the splicer is arranged behind the printer, viewed opposite to the longitudinal direction, and the return section now extends beyond the splicer; the above statements regarding the return section above the printer apply analogously. In particular, if necessary, the aforementioned bridge above the splicer is also raised in a similar manner in order to increase the aforementioned gap accordingly perpendicular to the longitudinal direction. In this embodiment, the paper web that is printed with the printer downstream of the splicer is also output via the splicer. By extending the return section beyond the splicer, the length of the return section is correspondingly increased and thus also the residence time (at a constant conveying speed) of the printed paper web for drying.

[0031] The additional possible installation space above the splicer, i.e. in particular the space between the splicer and the bridge, is advantageously used as an alternative or in addition to the extension of the return section described above to accommodate a system station for treating, examining or handling the paper web before it enters the printer and is printed there. The system station is, for example, a pre-treatment unit. Analogous to the return section, the system station is then expediently arranged above the splicer. In a corresponding embodiment, the splicer then outputs the paper web that is to be printed by the printer, and the corrugator has a system station, which is arranged above the splicer, for treating the paper web upstream of the printer.Alternatively, the system station can be located not above the splicer, but before or after the splicer, and particularly in the immediate vicinity. This makes advantageous use of the corresponding installation space before or after the splicer. The paper web leaves the splicer, is guided downstream into the system station, where it is pretreated, and then further downstream into the printer for printing. Analogous to the change of assembly level from the printer to the return section, the paper web also changes assembly level from the splicer to the system station, and the assembly level is changed again from the system station to the printer. This means that the overall length of the corrugator remains unchanged.The system station above the splicer is suitably a unit for tempering, humidifying, primer application, corona pretreatment, edge trimming, web inspection, web tension control, lateral control or the like or a combination thereof.

[0032] Alternatively or in addition to the system station above the splicer, in a suitable embodiment, a system station is arranged along the drying section, preferably along the reverse section and / or along the vertical section and / or above the printer. The statements regarding the system station above the splicer apply accordingly to the system station along the drying section.

[0033] The reverse section is expediently adjustable in length, meaning it has an adjustable length. This advantageously allows the dwell time (and thus the extent of drying) to be adjusted, while the adjustable length is also advantageous for threading the printed paper web into the reverse section. The length of the reverse section is controlled, for example, depending on the result of a print image inspection. A web inspection unit, located either inside or downstream of the drying section, examines the printed paper web to determine whether the print image is smeared. If the print image is smeared, the length is increased; otherwise, it is maintained or reduced.For example, a drying unit is arranged along the drying section in such a way that, depending on the length of the reverse section, the drying section only partially extends into the drying unit and the paper web is dynamically moved into and out of a drying area of ​​the drying unit.

[0034] In a suitable embodiment, the return section has a dancer and is therefore length-adjustable for setting a residence time (i.e. drying time) for drying the printed paper web. The dancer is in particular a deflection element as already described above. The dancer is characterized in particular in that it can be moved to adjust the length of the return section, in particular in and against the longitudinal direction. By moving the dancer against the longitudinal direction, the return section and the residence time are then extended and conversely by moving it in the longitudinal direction they are correspondingly shortened. However, the dancer does not necessarily have to be movable along the longitudinal direction, but can in principle also be movable alternatively or additionally at an angle or perpendicular to this, i.e. upwards and downwards.

[0035] In an advantageous development, the dancer can be guided to a front of the printer for threading the printed paper web into the reverse section. The dancer can therefore be moved forward, in particular, to a threading position. The threading position is, in particular, a final position for the dancer, so that a minimum length of the reverse section is simultaneously set in the threading position. The threading position is expediently located in front of the front of the printer, so that the dancer is then easily accessible from in front of the printer.

[0036] Analogously, the vertical section is alternatively or additionally adjustable in length; the above statements apply accordingly.

[0037] In the method according to the invention for operating a corrugated board plant (operating method), the plant extends in a longitudinal direction from a rear side to a front side, has a wet end which begins at the rear side and a dry end which ends at the front side, and is designed to produce corrugated board from several paper webs. The corrugated board plant furthermore has a printer with which one of the paper webs is printed so that this then becomes a printed paper web with a printed side. The corrugated board plant additionally has a drying section for the printed paper web, wherein the drying section begins at the printer and wherein the drying section has a return section which leads in the direction of the rear side so that the printed paper web is guided on the return section counter to the longitudinal direction. The statements regarding the corrugated board plant also apply accordingly to the method.

[0038] Another method according to the invention serves to convert an original corrugated board plant to a corrugated board plant as described above (conversion method). The original corrugated board plant does not necessarily have a printer and in any case does not have a drying section; rather, one is retrofitted as part of the method. However, the original corrugated board plant has a bridge, below which a printer is or is arranged. As part of the method, the bridge is now raised so that an intermediate space between the printer and the bridge is enlarged, and a rear section of a drying section is then arranged in the intermediate space for drying a paper web printed with the printer. The statements regarding the corrugated board plant and the method for operating such a plant also apply accordingly to the conversion method.

[0039] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In each case, schematically: Fig. 1 a corrugated board plant, Fig. 2 a section of the corrugated board plant Fig. 1, Fig. 3 a section of a variant of the corrugator from Fig. 1, Fig. 4 shows a further variant of the corrugated board plant from Fig. 1, Fig. 5 shows a further variant of the corrugated board plant from Fig. 1, Fig. 6 shows a further variant of the corrugator from Fig. 1.

[0040] In Fig. 1 shows an embodiment of a corrugated board plant 2 according to the invention, Fig. 2 shows a section of it in detail. The corrugated board plant 2 extends in a longitudinal direction L from a back side 4 to a front side 6. The corrugated board plant 2 has a wet end 8, which begins at the back side 4, and a dry end 10, which ends at the front side 6. The corrugated board plant 2 is designed to produce corrugated board from a plurality of paper webs 12. The paper webs 12 are each unwound from an unwind unit 14, conveyed through the corrugated board plant 2 and processed in the process. The unwind units 14 are each plant stations 16 of the corrugated board plant 2. In the wet end 8, the paper webs 12 are assembled to form the corrugated board web 18. For this purpose, the corrugated board plant 2 has one or more single facers 20, a preheater 22, a gluing unit 24 and a double facer 26. In the dry end 10, which begins downstream of the double facer 26, the corrugated cardboard web 18 is finished as required by means of suitable system stations 16 (not shown).However, the exact configuration of the dry end 10 is not important in this case. The longitudinal direction L corresponds to a general conveying direction through the corrugator 2, i.e., the paper webs 12 and the corrugated board web 18 are generally conveyed in the longitudinal direction L, but are locally deflected as needed using appropriate deflection elements.

[0041] The corrugator 2 has a printer 28 for printing one of the paper webs 12, so that this then becomes a printed paper web 12a with a printed side 30. The other, opposite side of the paper web 12a typically remains unprinted.

[0042] The corrugated board system 2 further comprises a drying section 32 for the printed paper web 12a. The paper web 12 that is printed with the printer 28 is subsequently conveyed through the drying section 32, so that the printed paper web 12a dries along the drying section 32; this occurs in particular before further processing in another system station 16 and in any case before contact of the printed side 30 with a component of a system station 16. For this purpose, the mere additional dwell time generated by the drying section 32 (passive drying) is typically sufficient. Optionally, the corrugated board system 2 comprises a system station 16, which is arranged along the drying section 32, for the treatment, handling, or inspection of the paper web. Fig. 2 shows by way of example that the drying section 32 has a drying unit 34 for additional drying of the printed paper web 12a (active drying).

[0043] The drying section 32 begins at the printer 28 (more precisely: at a print head 36 of the printer 28).

[0044] In the illustrated embodiment, the drying section 32 has a vertical section 37 and a reverse section 38. The vertical section 37 extends upwards (alternatively: downwards) with respect to the longitudinal direction L, i.e., in particular perpendicularly or generally at an angle greater than 0° and here even at least 60° to the longitudinal direction L. The reverse section 38 adjoins the vertical section 37 and extends in the direction of the rear side 4, so that the printed paper web 12a is guided on the reverse section 38 counter to the longitudinal direction L. This is also referred to as reverse guidance. The printed paper web 12a is therefore not guided further downstream of the printer 28 in the general conveying direction (longitudinal direction L) to the next system station 16, but first in the opposite direction, namely backwards, i.e., counter to the longitudinal direction L and behind the printer 28.

[0045] In the exemplary embodiment, both a vertical section 37 and a reverse section 38 are shown, but in principle it is also possible to have a design with only a vertical section 37 or only a reverse section 38, depending on the orientation of the printer 28 and the direction in which it outputs the paper web 12a.

[0046] In the illustrated embodiment, the printed paper web 12a is output by the printer 28 in the longitudinal direction L, i.e., forwards, and from there, by means of a suitable (first) deflection element 39, first upwards (or downwards), then deflected by means of a (second) deflection element 40 toward the rear side 4, i.e., backwards. This deflection element 40 marks an end of the vertical section 37 and also a beginning of the reverse section 38 and has no contact with the printed side 30, but only with the opposite, unprinted side. Alternatively, the printed paper web 12a is output by the printer 28 directly opposite the longitudinal direction L, i.e., backwards. The reverse section 38 then begins directly at the printer 28 or its print head 36 (not shown). Alternatively or additionally, a vertical section 37 is provided (also not shown).Independently of this, the drying section 32 also has an end, which is marked by a (third) deflection element 42, with which the printed paper web 12a is deflected again, in this case again forward. In . Fig. 2, the return section 38 also ends at the deflection element 42. This deflection element 42 also has contact with the printed side 30. From the printer 28 to the end of the return section 38, however, the printed side 12a remains untouched.

[0047] The deflection elements 39, 40, 42 have one or more deflection rollers for deflecting the printed paper web 12a. Optionally, one or more deflection elements 39, 40, 42 (or other Fig. 2 not explicitly designated deflection elements) so that the printed paper web 12a is additionally heated by means of the respective deflection element 39, 40, 42 and thereby dried.

[0048] In the present case, the drying section 32 is defined by the fact that it begins at the print head 36 of the printer 28 and ends at the deflection element 42, and that the printed side 30 remains untouched between the print head 36 and the deflection element 42. Instead, only the non-printed side of the paper web 12a is touched—if necessary. Optionally, the deflection element 42, which first comes into contact with the printed side 30 downstream of the printer 28, has a special non-stick coating that reduces the adhesion of the ink to the deflection element 42.

[0049] The drying section 32 is generally arranged downstream of the printer 28 and guides the printed paper web 12a first upwards due to the vertical section 37 and, due to the reverse section 38, behind the printer 28. A next system station 16 (here the preheater 22) is arranged downstream of the drying section 32. The next system station 16 is in the Fig. 1 and Fig. 2 spatially arranged in front of the printer 28, alternatively behind it (not shown).

[0050] Without limiting its generality, the following assumes the embodiment shown in the figures, in which the printer 28 is arranged in front of an unwinding unit 14 and behind a preheater 22. No further system stations 16 are arranged between the unwinding unit 14 and the printer 28, or between the printer 28 and the preheater 22. A paper web 12 is unwound by the unwinding unit 14, which is guided to the printer 28 and printed there. The now printed paper web 12a is then guided via the drying section 32 to the preheater 22. The unwinding unit 14, the printer 28 and the preheater 22 are arranged in a common assembly plane M1, but the drying section 32 is located in a different assembly plane M2, in the present case in an assembly plane M2 above the printer 28 and also above the unwinding unit 14. As an alternative to the position of the printer 28 shown, alternative positions A for the printer 28 are also possible, two of which are shown in Fig. 1. These alternative positions A shown are located at the rear 4 of the corrugator 2, accordingly the printer 28 can be positioned in the mounting plane M1 at the rear 4 or in a mounting plane M2, M3 above and here above the unwind unit 14 positioned furthest to the rear.

[0051] Downstream of the preheater 22, the paper webs 12, 12a are fed into the gluing unit 24; the preheater 22 serves for preconditioning. Still within the gluing unit 24 or downstream thereof, the paper webs 12, 12a are then pressed together to form the corrugated cardboard web 18 and fed into a heating section (i.e., the double-facer 26). The point at which the paper webs 12, 12a are pressed together to form the corrugated cardboard web 18 is also referred to as the gluing point 44. Analogously, the point at which ink is printed onto the paper web 12 in the printer 28 is referred to as the printing point 46. The entire drying section 32, but at least the reverse section 38, is now located above an imaginary connecting line 48 between the printing point 46 and the gluing point 44. In the embodiment shown, the reverse section 38 is at least 0.5 m and also at least 5 m long (measured along the paper web 12a).

[0052] In Fig. 3 shows a variant in which the drying section 3 is further extended by being folded, with several sections 38, 50, on which the paper web 12a is guided alternately in the direction of the back side 4 (to the rear) and in the direction of the front side 6 (to the front). Those sections 38 on which the paper web 12a is guided in the direction of the back side 4 are then each a backward section 38, as already described. The remaining sections 50 are analogously each referred to as a forward section 50. This results in a spiral or meandering course of the paper web 12a along the drying section 32, depending on the design. For example, as in Fig. 3 - the printed paper web 12a is output from the printer 38 forwards with the print image facing downwards and is guided downstream of the printer 28, initially along a first backward section 38 in the direction of the rear side 4 by a deflection element 40, which engages the unprinted side 30. Then, the printed paper web 12a is deflected back towards the front side 6 along a first forward section 50 by means of a further deflection element, which also engages the unprinted side 30. This concept can, in principle, be repeated several times depending on the available installation space (in Fig. 3, this is repeated once, resulting in a total of two reverse sections 38), so that the paper web 12a alternately passes through several reverse sections 38 and, if necessary, also several forward sections 50. In this case, each deflection element always engages only the unprinted side 30. Finally, however, the printed paper web 12a must be guided to the next system station 16 by means of at least one final deflection element 42, which then marks the end of the drying section 32. This final deflection element 42 then inevitably engages the printed side 30 of the paper web 12a.

[0053] The corrugator 2 has a bridge 52. The bridge 52 serves to temporarily store semi-finished products 12b for the corrugated board web 18, namely products from one or more single facers 20, each of which produces a corrugated paper web and joins it to a non-corrugated, flat paper web to form a so-called half-wave. The bridge 52 is arranged in an assembly plane M2 above the assembly plane M1 of the printer 28.

[0054] In the embodiment shown here, the printer 28 is arranged below the bridge 52. The printer 28 serves in this case for printing a so-called lamination web, i.e. the paper web 12 which is then subsequently assembled with one or more half-waves to form the corrugated cardboard web 18 and then forms an outer layer of the corrugated cardboard web 18. Accordingly, the unwinding unit 14, which outputs the paper web 12 to the printer 28, is also arranged below the bridge 52. The return section 38 is now arranged within the bridge 52 or in an intermediate space 54 between the printer 28 and the bridge 52. The drying section 32, specifically at least its return section 38, is placed in an assembly plane M2 above the printer 28. This assembly plane M2 corresponds either to the assembly plane M2 of the bridge 52 (as in Fig. 2), so that the rear section 38 is located in the bridge 52, or an additional mounting plane M3 for the rear section 38 is inserted between the printer 28 and the bridge 52 by raising the bridge 52 accordingly. This is exemplified in Fig. 4. This increases the height of the corrugator 2, but not its overall length.

[0055] The bridge 52 shown here has a walkway 56, from which the reverse section 38 is accessible for manually threading the printed paper web 12a into the reverse section 38. The walkway 56 runs laterally along the bridge 52 in the longitudinal direction L. The walkway 56 originally serves as access to the bridge 52 in order to be able to carry out maintenance or the like thereon if necessary. From the walkway 56, the reverse section 38 is now also accessible, in Fig. 2 are both on the same level. This makes it possible to thread the printed paper web 12a into the reverse section 38 from the catwalk 56. This is possible, for example, in the Fig. 2, in which the printer 28 has a height 58 which is greater than a person, here approximately 2 m to 2.5 m, so that threading from the mounting level M1 (floor level) of the printer 28 is difficult.

[0056] The corrugated board machine 2 further comprises a splicer 60. The splicer 60 is part of an unwinding unit 14, which also comprises two unwinders 62. A paper web 12 is alternately unwound from the unwinders 62; during a roll change, the splicer 60 connects the end of one paper web 12 to the beginning of the other paper web 12. In the exemplary embodiment shown here, the splicer 60 is arranged above the two unwinders 60.

[0057] In the present case, the splicer 60 is arranged behind the printer 28, viewed opposite to the longitudinal direction L, and the rear section 38 now extends beyond the splicer 60; the above statements regarding the rear section 38 above the printer 28 apply analogously. Fig. 4, the aforementioned bridge 52 is raised above the splicer 60 in order to enlarge the aforementioned gap 54 perpendicular to the longitudinal direction L. Via the Fig. The splicer 60 shown in Figures 2 to 6 also outputs the paper web 12 that is printed downstream of the splicer 60 with the printer 28. By extending the return section 38 beyond the splicer 60, the length of the return section 38 is increased accordingly and thus also the residence time of the printed paper web 12a for drying.

[0058] The additional possible installation space above the splicer 60, ie the space 54 between the splicer 60 and the bridge 52, is used alternatively or in addition to the above-described extension of the reverse section 38 to accommodate a system station 16 for treating, examining or handling the paper web 12 before it enters the printer 28 and is printed there. An embodiment of this is shown in Fig. 5. The system station 16, for example, is a pretreatment unit. The paper web 12 leaves the splicer 60, is guided downstream into the system station 16, where it is pretreated, and then further downstream into the printer 28 for printing. Analogous to the change of assembly levels M1, M2, M3 from the printer 28 to the return section 38, the paper web 12 also changes assembly levels M1, M2, M3 from the splicer 60 to the system station 16. Likewise, the assembly levels M1, M2, M3 are changed again from the system station 16 to the printer 28. The overall length of the corrugator 2 thus remains unchanged.

[0059] Alternatively or in addition to the system station 16 above the splicer 60, a system station 16 is arranged along the drying section 32, e.g. along the vertical section 37 and / or along the reverse section 38 and / or above the printer 28. Such a system station 16 is in Fig. 1 is shown as an example of a drying unit 34, but other configurations for the system station 16 are also possible. The explanations for the system station 16 above the splicer 60 apply accordingly.

[0060] In the embodiment of the Fig. 6, the return section 38 is length-adjustable, i.e. has an adjustable length. On the one hand, this allows the dwell time to be adjusted, and on the other hand, the adjustable length is also advantageous for threading the printed paper web 12a into the return section 38. In the embodiment shown here, the return section 38 has a dancer 64 and is therefore length-adjustable for setting a dwell time for drying the printed paper web 12a. In the present case, the dancer 64 corresponds to the deflection element 42, but this is not mandatory. The dancer 64 can be moved in and against the longitudinal direction L to adjust the length of the return section 38. In principle, the dancer 64 can also be moved obliquely or perpendicularly to the longitudinal direction L, i.e. up and down (not shown), alternatively or additionally. Analogously, in an embodiment not shown, the vertical section 37 is length-adjustable.

[0061] In the Fig. In the embodiment shown in Figure 6, the dancer 64 can even be guided up to a front side 66 of the printer 28 for threading the printed paper web 12a into the reverse section 38. The dancer 64 can therefore be moved forward to a threading position 68, which here is also an end position for the dancer 64, so that in the threading position 66, a minimum length of the reverse section 38 is simultaneously set. The threading position 66 is also located in front of the front side 66 of the printer 28. List of reference symbols 2 corrugated board lines 4 Back 6 Front 8 Wet End 10 Dry End 12 paper web 12a printed paper web 12b Semi-finished product (half-wave) 14 Unwinding unit 16 plant stations 18 corrugated board web 20 single facers 22 preheaters 24 Glue plant 26 Double Facers 28 Drucker 30 printed pages 32 drying section 34 drying unit 36 printing head 37 vertical section 38 reverse section 39 first deflecting element 40 (second) deflecting element 42 (third) deflecting element 44 bonding point 46 printing point 48 connecting line 50 forward section 52 bridge 54 gap 56 run step 58 height 60 splicer 62 unwind roller 64 dancer 66 front side 68 threading position A alternative positions for the printer L longitudinal direction M1, M2, M3 mounting plane

Claims

[1] Corrugated board plant (2), a. which extends in a longitudinal direction (L) from a rear side (4) to a front side (6), b. which has a wet end (8) which begins at the back (4) and a dry end (10) which ends at the front (6), c. which is designed to produce corrugated cardboard from several paper webs (12, 12a), d. which has a printer (28) for printing one of the paper webs (12) so that it is then a printed paper web (12a) with a printed side (30), e. which has a drying section (32) for the printed paper web (12a), f. the drying section (32) begins at the printer (28). [2] Corrugated board plant (2) according to claim 1, wherein the drying section (32) has a reverse section (38) which leads in the direction of the rear side (4), so that the printed paper web (12a) is guided on the reverse section (38) counter to the longitudinal direction (L). [3] Corrugated cardboard plant (2) according to claim 1 or 2, wherein the drying section (32) has a vertical section (37) which leads upwards or downwards with respect to the longitudinal direction (L). [4] Corrugated board plant (2) according to one of claims 1 to 3, wherein the drying section (32) is defined in that it begins at a print head (36) of the printer (28) and ends at a deflection element (42) and that the printed side (30) remains untouched between the print head (36) and the deflection element (38). [5] Corrugator (2) according to one of claims 1 to 4, wherein the rear section (38) is at least 0.5 m long. [6] Corrugated cardboard plant (2) according to one of claims 1 to 5, wherein said bridge (52) has a bridge (52) under which said printer (28) is arranged, wherein the rearward portion (38) is disposed within the bridge (52) or in a space (54) between the printer (28) and the bridge (52). [7] Corrugated board plant (2) according to claim 6, wherein the bridge (52) has a walkway (56) from which the return section (38) is accessible for threading the printed paper web (12a) into the return section (38). [8] Corrugated cardboard plant (2) according to one of claims 1 to 7, wherein said splicer (60) is arranged behind the printer (28) viewed opposite to the longitudinal direction (L), wherein the rearward portion (38) extends beyond the splicer (60). [9] Corrugated cardboard plant (2) according to one of claims 1 to 8, wherein said splicer (60) is arranged behind the printer (28) viewed opposite to the longitudinal direction (L), wherein the splicer (60) outputs the paper web (12) which is printed by the printer (28), wherein said device comprises a system station (16) for treating, examining or handling the paper web (12) upstream of the printer (28). [10] Corrugated board plant (2) according to one of claims 1 to 9, wherein a plant station (16) is arranged along the drying section (32) for treating, examining or handling the printed paper web (12a) downstream of the printer (28). [11] Corrugated board plant (2) according to one of claims 1 to 10, wherein the rear section (38) has a dancer (64) and is thereby adjustable in length for setting a residence time for drying the printed paper web (12a). [12] Corrugated board plant (2) according to claim 11, wherein the dancer (64) can be guided up to a front side (66) of the printer (28) for threading the printed paper web (12a) into the rear section (38). [13] Corrugated cardboard plant (2) according to one of claims 1 to 12, wherein the drying section (32) is designed to be folded, with a plurality of sections (38, 50) on which the printed paper web (12a) is guided alternately in the direction of the back side (4) and in the direction of the front side (6). [14] Method for operating a corrugated board plant (2), a. which extends in a longitudinal direction (L) from a rear side (4) to a front side (6), b. which has a wet end (8) which begins at the back (4) and a dry end (10) which ends at the front (6), c. which is designed to produce corrugated cardboard from several paper webs (12, 12a), d. which has a printer (289) with which one of the paper webs (12) is printed, so that this is then a printed paper web (12a) with a printed side (30), e. which has a drying section (32) for the printed paper web (12a), f. the drying section (32) begins at the printer (28). [15] Method for converting an original corrugated board plant into a corrugated board plant (2) according to one of claims 1 to 13, wherein the original corrugator has a bridge (52) below which a printer (28) is or is arranged, wherein the bridge (52) is raised so that a gap (54) between the printer (28) and the bridge (52) is increased, wherein a rear section (38) of a drying section (32) is then arranged in the intermediate space (54) for drying a paper web (12a) printed with the printer (28).

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