Method for operating a system having a corrugator and a printing machine, and system

Description

[0001] The invention relates to a method for operating a plant which has a corrugated board plant and a printing machine, as well as to a corresponding plant.

[0002] A corrugator is used to produce corrugated board. Several paper webs are unwound from a separate unwinder and joined together to form a single corrugated board web. For this purpose, one of the paper webs is corrugated, for example, using a corrugating 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 using the corrugator.

[0003] Additionally, it is possible to pre-print one of the paper webs using a printing press to produce a correspondingly printed corrugated board web. The paper web is first printed and then fed to the corrugator for further processing. In principle, it is possible to first roll the printed paper web into a reel, feed this reel to a reel of the corrugator, and from there unroll the reel and process it. However, direct transfer of the printed paper web to the corrugator is desirable. However, coordinating the printing press with the corrugator is often problematic, particularly with regard to the speed and web tension of the printed paper web.

[0004] US 6,059,705 A discloses a carton blank processing apparatus having a rotatably mounted processing head for processing successive carton blanks. A carton blank alignment sensor is provided upstream of the processing head to detect a pre-printed alignment mark on a surface of an approaching carton blank. A controller responds to the alignment sensor to determine whether the approaching carton blank is properly aligned with the rotating processing head. An alignment correction window is defined by the controller to bring the angular position of the processing head into correct alignment with the linear position of the approaching carton blank.

[0005] DE 10 2017 222 314 A1 relates to a substrate feed device, wherein at least one primary acceleration means is arranged below a storage area of ​​the substrate feed device provided for storing a stack of sheets of a substrate, and wherein the substrate feed device has at least one frame and at least one lifting frame movable by means of a vertical drive relative to the at least one frame at least with respect to a vertical direction, and wherein the at least one primary acceleration means is carried by the at least one lifting frame and is arranged to be movable together with the at least one lifting frame with respect to the vertical direction, and wherein at least one height adjustment means is arranged,by means of which at least one upper end position of the at least vertical movement path of the at least one primary acceleration means, which can be effected by means of the at least one vertical drive, can be set and / or continuously adjusted as one of at least three different end positions independently of the at least one vertical drive.

[0006] US 2018 345 619 A1 discloses an apparatus for processing corrugated sheets, comprising a sheet processing device and a control system for controlling the sheet processing device, further comprising a visual inspection unit for reading printed information marks. The information marks are provided on at least one printed sheet or web. As the printed sheet or web, and thus the printed information marks to be read, pass through the corrugated board sheet processing device or corrugator past the visual inspection unit, the required cutting settings for the cutting device can be identified based on the read printed information marks, and the cutting device can then be controlled appropriately.

[0007] Against this background, it is an object of the invention to improve the joint operation of a corrugated board system and a printing press. To this end, an improved method for operating a system comprising a corrugated board system and a printing press is to be provided. Furthermore, a corresponding system is to be provided.

[0008] The object is achieved according to the invention by a method having the features according to claim 1 and by a system having the features according to claim 13. Advantageous embodiments, refinements, and variants are the subject of the dependent claims. The statements regarding the method also apply mutatis mutandis to the system, and vice versa. If steps of the method are specified below, advantageous embodiments for the system result from the system being designed to perform one or more of these steps. For this purpose, the system has, in particular, a correspondingly designed control unit.

[0009] The method is used to operate a system comprising a corrugated board system and a printing press. The corrugated board system has a number of processing units for processing one or more paper webs. Suitable processing units include, for example, an unwinder for unwinding a paper web, a splicer for providing a continuous paper web, particularly in combination with an unwinder, a corrugating roll for producing a corrugated paper web, a gluing unit for applying glue to a paper web for the purpose of joining it to another paper web, a preheater for preheating a paper web, a single-facer for joining a corrugated paper web to a non-corrugated paper web to form a single-faced corrugated board web, a double-facer for joining a single-faced corrugated board web to a non-corrugated paper web to form a corrugated board web, and the like.Depending on the design of the corrugated board plant, the processing units mentioned may be single, multiple or not present at all.

[0010] The printing press prints a paper web and delivers it as a printed paper web to the corrugator for further processing into a corrugated board web. The term "printed paper web" is used to simplify matters by describing the paper web that passes through the printing press and is printed by it. The printed paper web preferably serves as a liner for the corrugated board web, i.e., as its outermost layer.

[0011] Preferably, the printing press is a digital printer. Such a configuration is assumed below without restriction of generality. In a suitable configuration, the printing press has a printing cylinder and a number of printing bars for printing an incoming paper web. The printing cylinder is, in particular, part of a printing unit, which in turn is a processing unit of the printing press. "A number of" is generally understood to mean "one or more." The incoming paper web is provided, for example, by a combination of an unwinder and a splicer. A configuration with several printing cylinders and associated printing bars, through which the paper web passes one after the other, is also suitable. For example, a first combination of printing cylinder and printing bars is used to print a number of inks, e.g.four-color (CMYK), and then a varnish is applied using a second combination of printing cylinder and printing bars. The printing cylinder for printing ink is also called an inkjet printing cylinder; similarly, the printing cylinder for printing varnish is also called a varnish printing cylinder. In addition, the printing press advantageously has one or more application units, e.g., for primer or varnish, and / or one or more dryers, e.g., hot-air dryers or IR dryers, for drying the print.

[0012] The spatial arrangement of the printing press relative to the corrugator is fundamentally arbitrary. The only important thing is that the printed paper web is fed directly to the corrugator, i.e. is not first wound up and then unwound again in the corrugator. In the present case, without loss of generality, an arrangement is assumed in which the printing press is arranged parallel next to the corrugator, with the printed paper web being fed into the corrugator via a number of, for example, two turner bars. In principle, however, an inline arrangement is also suitable. Preferably, the printed paper web is fed into the corrugator via a combination of an unwinder and a splicer, so that the printing press can optionally be uncoupled from the corrugator and switched off, and then another paper web is fed in via the unwinder.

[0013] The system features a speed control system that specifies the speed of a leading machine for a number of downstream machines, so that these machines follow the leading machine. The speed is, in particular, a conveyor speed or a web speed, and then a speed of a specific paper web within the system, specifically the printed paper web and the corrugated board web as a whole. The speed control system then specifies the overall speed of the leading machine as the target speed for the downstream machines and regulates these downstream machines accordingly.

[0014] In this case, the printing press is the lead machine, and at least one of the processing units of the corrugator is a downstream machine. Preferably, all processing units of the corrugator are each downstream machines, so that the corrugator completely follows the printing press, at least with regard to speed control. This has the advantage that the printing press can be defined as the resting point of the system and can therefore be operated at a constant speed. This results in a significantly improved printing result with the printing press, especially compared to the reverse case, in which the printing press follows the corrugator as the lead machine.Such a configuration, with the printing press as a downstream machine, is possible in itself and has the advantage that its combination with a corrugator is particularly simple, since the corrugator does not require any further modifications and can be operated as usual; the printing press simply replaces one of the corrugator's unwinders for feeding the paper web. For example, a given corrugator already has a speed control system, with the double-facer setting the target speed to which the other processing units and then also any additional printing press are aligned. However, this so-called natural solution has been deliberately abandoned in this case. This allows the printing result to be improved.In addition, with the printing press as the leading machine, any tension control or dancer to adjust the speed of the printing press to the corrugator can be dispensed with, which makes the installation of the system simpler in this respect.

[0015] As already indicated, the printing press is preferably operated at a constant speed and then advantageously forms a calm center of the entire system. In a suitable embodiment for this, the printing press has a printing cylinder for printing the paper web, in particular an inkjet printing cylinder as already described, which is controlled by the speed control to a constant speed (= predetermined speed), in particular during web transport, which is a first operating mode. This ensures that the paper web runs as smoothly as possible during printing. The speed control then contains two control systems: a first control system controls the speed of the printing press to a constant value, and a second control system then controls the corrugator system to the speed of the printing press.

[0016] Preferably, the speed control provides a virtual master axis, which the printing press, specifically the aforementioned printing cylinder, follows. The virtual master axis is not an actual axis of the printing press, but is provided purely electronically by a control unit of the system and parameterized accordingly. The use of a virtual master axis has the advantage over a real master axis (e.g., encoder) that the virtual master axis generates a particularly smooth, i.e., not only low-noise, but even noiseless encoder signal for control. A "real master axis" is understood here in particular to mean that the system follows a measured speed (encoder signal). However, the details of the virtual master axis are of secondary importance here; what is important is that one is used at all.Preferably, the control unit providing the virtual master axis is part of the printing press and is then also referred to as the printer control system. Accordingly, the virtual master axis is then also passed from the printer control system via a suitable signal path to a control unit of the corrugator (also referred to as a corrugator control system), in order to regulate the speed of the individual processing units accordingly. However, the distribution of the control units and the control tasks between the printing press and the corrugator, or even separately, is essentially possible. Therefore, without loss of generality, we will refer to the "control unit of the system" in the present context.

[0017] However, the virtual master axis is not completely independent in that the speed to which the printing cylinder is controlled (i.e. the target speed) is predetermined, suitably by the corrugator, e.g. automatically as part of a setting to carry out a specific job or manually by a machine operator. If, for example, the speed of the corrugator needs to be changed due to a job change and a corresponding speed is entered or set, this changes the speed of the virtual master axis, so that as a result the corrugator is also operated at a correspondingly changed speed. In this way, the control structure and operating concept, in which job-dependent changes are made to the corrugator, are advantageously retained.

[0018] The printing cylinder, in particular the inkjet printing cylinder, of the printing press follows the virtual master axis preferably without a process controller and is thus excluded from any web transport control, i.e. control of the web tension of the paper web. However, such a web transport control is expediently part of the corrugator, i.e. in one or more of the processing units of the corrugator, the web tension of the various paper webs is controlled by means of a web transport control. The web tension is preferably controlled separately in each processing unit. At least the printing cylinder is preferably excluded from this web transport control, but other sections of the printing press apart from the printing cylinder are optionally connected to the web transport control in order to regulate the web tension within the printing press (but apart from the printing cylinder) and between the printing press and the corrugator.Accordingly, a web transport control concept has been implemented for the entire system, in which the web tension is controlled in various sections of the system, with the specific exception of the printing cylinder. This is controlled solely by the speed control, which the corrugator then also follows, so that ultimately the web transport control is also dependent on the speed control. The printing cylinder follows the virtual master axis, as do all other drives in the system. However, unlike the printing cylinder, these other drives also adjust their speed via the web transport control, i.e., via the control value of a process controller, e.g., for web tension or dancer roller.

[0019] Preferably, the drives of the virtual master axis follow the axis in angular synchronization. This specifically means that, in addition to the speed control, a position control is also active. If an actual speed deviates from a target speed, this results in a position error, which is then corrected by a position controller.

[0020] In summary, a specified speed for the corrugator is advantageously used as the speed for the printing press, which the corrugator then follows, while simultaneously regulating the web tension, from which the printing cylinder, however, is excluded. This design is particularly suitable for web transport, i.e., for conveying the paper web through the system during the production of a corrugated board web. During web transport, the paper web is therefore conveyed. Web transport is (as already mentioned above) a first operating mode of the system, which serves the actual production of a corrugated board web.

[0021] With multiple printing cylinders, not all printing cylinders are necessarily excluded from the web transport control during the web transport. In a preferred embodiment, only the inkjet printing cylinder is excluded from the web transport control, while the varnish printing cylinder is connected to it.

[0022] Fundamentally, the system advantageously comprises, as part of the web tension control concept, one or more pairs of rollers over which the printed paper web is conveyed one after the other and with which the web tension of the printed paper web is regulated before it enters the corrugator downstream of the printing press. Each pair of rollers has a measuring roller (non-driven) for measuring the web tension (actual value) and a control roller (driven) for setting the web tension to a target value. Control rollers can be, for example, cooling rollers, heating rollers, tempering rollers, pressure rollers, adjusting rollers or the printing cylinders already mentioned. A wide variety of designs are suitable for the arrangement of the pairs of rollers along the paper web. The measuring roller of a pair of rollers can also be arranged either upstream or downstream of the control roller of the pair of rollers.Preferably, however, there is no measuring roller or control roller of a second roller pair between the non-driven measuring roller and the driven control roller of a first roller pair.

[0023] In contrast to web transport, for simple tensioning of the paper web, an embodiment is advantageous in which, contrary to what has been said so far, the control of the web tension is changed, specifically by using one or more printing cylinders of the printing press to control the web tension in the printing press. In this case, however, the paper web is only tensioned and not conveyed. Tensioning is a second operating mode of the system. In principle, the same control system and thus the same control direction can be used for tensioning as for web transport. However, changing the control system, in particular so that the printing cylinder of the printing unit is now used, is particularly advantageous when the printed paper web is prepared for splicing using a splicer (in particular a laminating web splicer). During web transport, the printing press (more precisely the printing unit and even more precisely its printing cylinder) forms a resting point.The control is then changed in such a way that the printing press is no longer the resting point of the system, but the splicer, by reversing the control direction, so to speak. In this way, tensioning takes place in preparation for splicing. This makes it possible to tension the paper web, which is clamped on the splicer for splicing, upstream and through the printing press. The splicer forms a first clamping point, a second clamping point is arranged upstream along the paper web and is formed, for example, by another splicer at the inlet to the printing press. In contrast to web transport, when tensioning the printing cylinders, in particular the inkjet printing cylinder, a control roller which, with a measuring roller, forms a pair of rollers for regulating the web tension is used. The measuring roller is also a part of the printing press.

[0024] In a suitable embodiment, the system has a plurality of measuring rollers and control rollers, which are arranged alternately along the printed paper web, so that there is a control roller between two measuring rollers and vice versa. By changing the assignment of the measuring rollers and control rollers to each other in roller pairs, the control direction of each roller pair for web tension control can be changed. Preferably, all roller pairs upstream of the printing cylinder (particularly inkjet printing cylinders) are the same during web transport and tensioning, i.e. the control direction upstream of the printing cylinder remains unchanged. Advantageously, however, from the printing cylinder and downstream thereof for tensioning (especially for the preparation of the splicing of the printed paper web as described above), the control direction is reversed compared to web transport. For this purpose, a different measuring roller is assigned to each control roller (or vice versa).

[0025] For example, the roller pairs starting from the printing cylinder and downstream of it during web transport are formed such that the control roller of each roller pair is downstream of the corresponding measuring roller. For tensioning, a measuring roller upstream of this control roller is then conversely assigned to the respective control roller. This measuring roller may have previously been the measuring roller of another roller pair during web transport. Preferably, for tensioning, all roller pairs are formed such that in each roller pair the control roller is downstream of the corresponding measuring roller, so that control overall takes place in only one direction, towards the inlet of the printing press. Based on this, during web transport the roller pairs starting from the printing cylinder (ink printing cylinder) and downstream of it are preferably formed such that the control roller is upstream of the corresponding measuring roller.As a result, the overall control is carried out starting from the pressure cylinder in opposite directions and away from the pressure cylinder (ie upstream of it in the upstream direction and downstream of it in the downstream direction).

[0026] As already indicated above, the corrugator is expediently controlled starting from its double facer (also referred to as the pulling and heating section). Accordingly, all other processing units of the corrugator preferably follow the double facer in terms of speed control. In other words, the speed of the other processing units is controlled depending on the speed of the double facer. This basic concept is preferably retained here, with the difference that the double facer no longer sets the speed independently, but follows the printing press in this respect as described, in particular the speed specified by the virtual lead axis. Since the other processing units now continue to follow the double facer, the corrugator as a whole is a downstream machine of the printing press.In other words, the double-facer, which was previously used as a master, now follows the printing press and is therefore only a master for the corrugator, not for the system as a whole. The printing press's impression cylinder is now the master for the entire system.

[0027] Since the double-facer is now to follow the printing press, an additional adjustment of the web tension between the printing press and the corrugator is particularly useful, as the speed of the double-facer, which was previously uncontrolled, is now controlled to match the speed specified by the printing press. This also applies in general if a processing unit other than the double-facer was previously the master.

[0028] To adjust the web tension between the printing press and the corrugator, a suitable design with the double-facer controls the web tension of the printed paper web on a final section before the double-facer. This also advantageously allows for speed adjustment upon entry into the corrugator, especially into the previously uncontrolled double-facer. To control the web tension on the final section, the system has a pair of rollers, with a control roller for adjusting the web tension on the final section and a measuring roller for measuring the web tension on the final section. The control roller is either part of the double-facer and the measuring roller is located outside of it and upstream of it, or vice versa. The term "final section" refers to the section between the measuring roller and the control roller.As an alternative to the described solution with a pair of rollers, a dancer between the double facer and the printing machine is also suitable for adjusting the web tension.

[0029] In a suitable configuration, feedback of the control loop is implemented with a dancer position or, alternatively, with a web tension measurement. Depending on the selected configuration, the measuring roller used is arranged at different positions. In a suitable configuration, a splicer is located between the printing press and the corrugator (more precisely, its double facer), so the dancer position is preferably used to adjust the speed of the corrugator or the double facer. However, if no such splicer is present at the specified position, a web tension measuring roller is expediently used to adjust the specified speed.

[0030] It is particularly advantageous to use a splicer to adjust the speed when entering the double facer. In In a suitable embodiment, the corrugated board system has a corresponding splicer, which is arranged along the printed paper web between the printing press and the double-facer, i.e., downstream of the printing press and upstream of the double-facer. The splicer has a measuring roller with which the web tension is measured, which is then controlled by the double-facer, in particular with a control roller as described. The splicer is, in particular, combined with an unwinder, via which the printed paper web is then fed into the corrugated board system. A different paper web can then be fed in if required by means of the unwinder and the splicer.

[0031] A system according to the invention has a control unit (in particular as already described above) which is designed to carry out a method as described above.

[0032] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In each case, the following schematically show: Fig. 1 a facility, Fig. 2 a section of the facility Fig. 1 in detail in a first operating mode, Fig. 3 the section of the system according to Fig. 2 in a different operating mode.

[0033] In Fig. 1 1 shows a highly simplified system 2 comprising a corrugated board system 4 and a printing press 6. The corrugated board system 4 has a number of processing units 8 for processing one or more paper webs. Suitable processing units 8 are, for example, an unwinder 10 for unwinding a paper web, a splicer 12 for providing a continuous paper web, a corrugating roller, a gluing unit, a preheater, a single-facer, a double-facer 14 for joining single-faced corrugated board webs with a non-corrugated paper web to form a corrugated board web 16, and the like.

[0034] The printing machine 6 prints a paper web and outputs it as a printed paper web 18 to the corrugator 4 for further processing into the corrugated board web 16. For the sake of simplicity, the term "printed paper web" describes the paper web that passes through the printing machine 6 and is printed by it.

[0035] In the illustrated embodiment, the printing machine 6 is a digital printer. An embodiment of the printing machine 6 is shown in the Fig. 2 and 3 which show sections of plant 2 in different operating modes. The corrugator plant 4 is shown in the Fig. 2 and 3only an unwinder 10, a splicer 12 and a double facer 14 are shown, via which the printed paper web 18 is fed to the corrugator 4. The printing press 6 here has, for example, two printing cylinders 20 and a number of printing bars 22 in order to print the incoming paper web 18. The incoming paper web 18 is provided here by a combination of an unwinder 10 and a splicer 12; this combination is also referred to as an unwind and splice unit E1 and forms an entrance to the printing press 6. Downstream of this is an optional inlet train group E2, downstream of this an optional corona pretreatment E3, downstream of this an optional precoating E4 and downstream of this then a printing unit E5 with the first printing cylinder 20 (ink printing cylinder) and printing bars 22 for printing a number of inks.Downstream of this, an optional varnishing E6 is carried out first, followed by an optional digital printing varnishing E7 with a second, not explicitly shown, printing cylinder 20 (varnishing cylinder) and printing bars 22.

[0036] The spatial arrangement of the printing machine 6 relative to the corrugated board machine 4 is basically arbitrary, in Fig. 1 For example, the printing machine 6 is arranged parallel to the corrugated board machine 4, whereby the printed paper web 18 is then fed into the corrugated board machine 4 via a number of turning bars 30. In the Fig. 2 and 3Only two turning bars 30 are shown as an example, but the number can vary; a design without turning bars 30 is also possible. In the present case, the printed paper web 18 is then fed to the corrugated board system 4 via a combination of an unwinder 10 and a splicer 12, so that the printing machine 6 can optionally also be uncoupled from the corrugated board system 4 and switched off, and then another paper web is fed to the corrugated board system 4 by means of the unwinder 10.

[0037] System 2 has a speed control 34, which specifies the speed of a leading machine for a number of downstream machines so that they follow the leading machine. The speed is a conveying speed or a web speed and then a speed of a respective paper web within system 2, specifically also the printed paper web 18 and the corrugated board web 16 as a whole. The speed control 34 specifies the overall speed of the leading machine as the target speed for the downstream machines and regulates these downstream machines accordingly. In this case, the printing press 6 is the leading machine, and at least one of the processing units 8 of the corrugated board system 4 is a downstream machine. In this case, the corrugated board system 4 even completely follows the printing press 6, at least with regard to speed control.

[0038] The printing press 6 is accordingly operated at a constant speed and then forms a resting point for the entire system 2. For this purpose, one of the printing cylinders 20 (in this case, the first printing cylinder 20 of the printing unit E5) is controlled to a constant speed by the speed control 34. In the illustrated embodiment, the speed control 34 also provides a virtual master axis 36, which the printing press 6, specifically its printing cylinder 20, follows. Fig. 1 A control unit 38 of system 2 is shown, which contains the speed control 34 with the virtual master axis 36. In principle, it is possible for the control unit 38 to be integrated into the printing press 6 or the corrugated board system 4 or to be distributed between them.

[0039] However, the virtual master axis 36 is not completely independent in that the speed to which the printing cylinder 20 is controlled is predetermined, e.g. by the corrugator 4. If, for example, the speed of the corrugator 4 is to be changed in the event of an order change and a corresponding speed is entered or set, the speed for the virtual master axis 36 is thereby changed, so that as a result the corrugator 4 is also operated at a correspondingly changed speed.

[0040] The first printing cylinder 20 of the printing press 6 follows the virtual master axis 36 without a process controller and is thus excluded from any web transport control, i.e., control of the web tension of the paper web 18. However, such a web transport control is presently part of the corrugated board system 4, i.e., the web tension of the various paper webs is controlled by a web transport control in the processing units 8 of the corrugated board system 4. At least the first printing cylinder 20 (ink printing cylinder) is excluded from this web transport control; however, other sections of the printing press 6 apart from the printing cylinder 20 are optionally connected to the web transport control, in this case also the second printing cylinder 20 (varnish printing cylinder).Accordingly, a web transport control concept is implemented for the entire system, in which the web tension is controlled on various sections of system 2, with the specific exception of the printing cylinder 20. This is only controlled by the speed control 34, which the corrugator system 4 then follows, so that the web transport control is also dependent on the speed control 34. This embodiment is suitable for web transport, i.e. for conveying the paper web 18 through system 2 during the production of a corrugated board web 16. This web transport is a first operating mode of system 2 and in . Fig. 2 shown.

[0041] Fundamentally, the system 2 comprises, as part of the web tension control concept, one or more pairs of rollers over which the printed paper web 18 is conveyed one after the other and with which a web tension of the printed paper web 18 is controlled before it enters the corrugator 4 downstream of the printing machine 6. The pairs of rollers are arranged in the Fig. 2 and 3 by arrows 44, whereby each arrow 44 begins at the measuring roller 42 of a roller pair and ends with its tip at the control roller 40 of the roller pair. For the sake of clarity, not all control rollers 40 and measuring rollers 42 are explicitly provided with reference symbols, but their position and function are clearly evident from the arrows 44 and their course. The course of the arrows 44, ie their orientation either upstream or downstream, indicates the respectively set control direction of the roller pair. As can be seen in the comparison of the Fig. 2 and 3As can be seen, the control direction can be changed by changing the assignment of the measuring rollers 42 and control rollers 40 to roller pairs. The respective control roller 40 is a driven roller, the respective measuring roller 42 is an undriven roller. Cooling rollers 46, heating rollers, tempering rollers, pressure rollers, adjusting rollers or the aforementioned printing cylinders 20 are used as control rollers 40. A wide variety of configurations are suitable for the arrangement of the roller pairs along the paper web 18; one possible embodiment is shown in the Fig. 2 and 3 shown.

[0042] In contrast to web transport, the printing cylinders 20 are used for simply tensioning the paper web 18, specifically the printing cylinder 20 of the printing unit E5 shown here, to regulate the web tension in the printing press 6. However, the paper web 18 is only tensioned and not conveyed. Tensioning is a second operating mode of system 2, and an embodiment of this is shown in Fig. 3 shown. The measuring rollers 42 and control rollers 40 are arranged alternately along the printed paper web 18, so that a control roller 40 is located between two measuring rollers 42 and vice versa between two control rollers 40. By changing the assignment of the measuring rollers 42 and control rollers 40 to each other to form roller pairs, the control direction for the web tension control can be changed. Fig. 2 and 3All roller pairs in front of the printing cylinder 20 shown have the same control direction during web transport and tensioning, ie upstream of the printing cylinder 20 the control direction remains unchanged. However, as shown in Fig. 3 As can be seen, from the printing cylinder 20 and downstream of it for tensioning the control direction is compared to the web transport in Fig. 2 vice versa. For this purpose, a respective control roller 40 is assigned to another measuring roller 42 (or vice versa), specifically in such a way that the explicitly shown printing cylinder 20 is also used as a control roller 40. According to Fig. 2 The roller pairs from the printing cylinder 20 and downstream of it during web transport are formed in such a way that the control roller 40 of a respective roller pair is located downstream of the associated measuring roller 42. For tensioning, then according to Fig. 3 Conversely, the respective control roller 40 is assigned a measuring roller 42 upstream of the control roller 40. This measuring roller 42 may previously have been the measuring roller 42 of a different roller pair during web transport. In the present case, for tensioning purposes, all of the roller pairs are even formed in such a way that in each roller pair the control roller 40 is located downstream of the associated measuring roller 42, so that the overall control takes place in only one direction towards the entrance of the printing press 6. Proceeding from this, during web transport the roller pairs from the printing cylinder 20 and downstream thereof are then formed in such a way that the control roller 40 is located upstream of the associated measuring roller 42. As a result, the overall control takes place starting from the printing cylinder 20 in opposite directions and away from the printing cylinder 20 (i.e. upstream of it in the upstream direction and downstream of it in the downstream direction).

[0043] The corrugated board system 4 is controlled in this case starting from the double facer 14. Accordingly, all other processing units 8 of the corrugated board system 4 follow the double facer 14 with regard to the speed control 34. Since the double facer 14 now follows the printing press 6, an additional adjustment of the web tension between the printing press 6 and the corrugated board system 4 is required because the speed of the double facer 14, which was previously not controlled, is now controlled to match the speed specified by the printing press 6. This also applies in general if a processing unit 8 other than the double facer 14 was previously a master of the corrugated board system 4.

[0044] To adjust the web tension between the printing press 6 and the corrugator 4, in the illustrated embodiment, the web tension of the printed paper web 18 is controlled on a last section 50 before the double facer 14. In this way, an adjustment of the speed upon entry into the corrugator 4 is realized. To control the web tension on the last section 50, the system 2 has a pair of rollers, with a control roller 40 for adjusting the web tension on the last section 50 and with a measuring roller 42 for measuring the web tension on the last section 42. Fig. 2 the control roller 40 is part of the double facer 14.

[0045] As in Fig. 2 As can be seen, two positions are suitable for the associated measuring roller 42 of the roller pair: a first possible measuring roller 42 is located between the corrugator 4 and the turning bar 30 upstream of the splicer 12, and a second possible measuring roller 42 is located downstream of the splicer 12 or is a part thereof. The term "last section" 50 refers to the section between the respective measuring roller 42 and the control roller 40. Fig. 2 Although both of the described measuring rollers 42 are shown, typically only one is used, depending on whether the splicer 12 is present or missing. List of reference symbols

[0046] 2System 4Corrugated board system 6Printing press 8Processing units 10Unwinder 12Splicer 14Double facer 16Corrugated board web 18Printed paper web 20Printing cylinder 22Printing bar 30Turning bar 34Speed ​​control 36Virtual guide axis 38Control unit 40Control roller 42Measuring roller 44Arrow (for marking a pair of rollers) 50Last section E1Unwind and splice unit E2Infeed pull group E3Corona pretreatment E4Precoating E5Printing unit E6Varnish E7Digital printing varnishing

Claims

1. A method for operating a system (2) having a corrugator (4) and a printing machine (6), - wherein the corrugator (4) has a number of processing units (8) for processing one or more paper webs (18), - wherein the printing machine (6) prints a paper web and outputs same as a printed paper web (18) to the corrugator (4), - wherein the system (2) has a speed controller (34) which specifies a speed of a lead machine for a number of follower machines, such that they follow the lead machine, - wherein the printing machine (6) is the lead machine, - wherein at least one of the processing units (8) of the corrugator (4) is a follower machine.

2. The method according to claim 1, wherein the printing machine (6) for printing the paper web (18) has a printing cylinder (20) which is controlled to a constant speed by the speed controller (34).

3. The method according to claim 2, wherein the printing cylinder (20) is used to control the web tension in the printing machine (6) to tension the paper web (18), wherein the paper web (18) is only tensioned and not conveyed.

4. The method according to claims 1 to 3, wherein the speed controller (34) provides a virtual guide axis (36) which the printing machine (6) follows.

5. The method according to any of claims 1 to 4, wherein the system (2) has one or more pairs of rollers over which the printed paper web (18) is conveyed and by means of which a web tension of the printed paper web (18) is controlled before said paper web runs into the corrugator (4) downstream of the printing machine (6).

6. The method according to claim 5, wherein each pair of rollers has a control roller (40) and a measuring roller (42), wherein, for tensioning purposes, all roller pairs are formed in such a way that, in each roller pair, the control roller (40) is located downstream of the associated measuring roller (42), and wherein, starting from this, during web transport, the roller pairs from the printing cylinder (20) and downstream thereof are formed in such a way that the control roller (40) is located upstream of the associated measuring roller (42).

7. The method according to claim 5 or 6, wherein, during web transport, the printing machine (6) forms a resting point, and, in order to prepare for splicing by a splicer (12), controlling the web tension is changed in such a way that the resting point of the system is no longer formed by the printing machine (6), but by the splicer (12).

8. The method according to any of claims 1 to 7, wherein one of the processing units (8) of the corrugator (4) is a double facer (14) to which the printed paper web (18) is fed.

9. The method according to claim 8, wherein all remaining processing units (8) of the corrugator (4) follow the double facer (14) with respect to the speed controller (34).

10. The method according to claim 8 or 9, wherein the double facer (14) controls a web tension of the printed paper web (18) on a last portion (50) before the double facer (14).

11. The method according to claim 10, wherein the corrugator (4) has a splicer (12) which is arranged between the printing machine (6) and the double facer (14), wherein the splicer (12) has a measuring roller (42) with which the web tension is measured in order to then be controlled by the double facer (14).

12. The method according to any of claims 1 to 11, wherein the printing machine (6) is a digital printer.

13. System (2) having a control unit (38) designed to carry out a method according to any of claims 1 to 12.