METHOD FOR OPERATING A SYSTEM HAVING A CORRUGATOR AND A PRINTING MACHINE, AND SYSTEM

Abstract

The invention relates to a method for operating a system (2) comprising 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 10 units (8) of the corrugator (4) is a follower machine. The invention also relates to a corresponding system (2).

Claims

1. Method for operating a system which has a corrugator and a printing machine, wherein the corrugator has a number of processing units for processing one or more paper webs, wherein the printing machine prints a paper web and outputs same as a printed paper web to the corrugator, wherein the system has a speed controller 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 is the lead machine, wherein at least one of the processing units of the corrugator is a follower machine.

2. Method according to claim 1, wherein the printing machine for printing the paper web has a printing cylinder which is controlled to a constant speed by the speed controller.

3. Method according to claim 2, wherein the printing cylinder is used to control the web tension in the printing machine to tension the paper web, wherein the paper web is only tensioned and not conveyed.

4. Method according to claim 1, wherein the speed controller provides a virtual guide axis which the printing machine follows.

5. Method according to claim 1, wherein the system has one or more pairs of rollers over which the printed paper web is conveyed and with which a web tension of the printed paper web is controlled before it runs into the corrugator downstream of the printing machine.

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

7. Method according to claim 5, wherein, during web transport, the printing machine forms a resting point, and, in order to prepare for splicing with a splicer, the control of the web tension is changed in such a way that the printing machine no longer forms the resting point of the system, but the splicer.

8. Method according to claim 1, wherein one of the processing units of the corrugator is a double facer to which the printed paper web is fed.

9. Method according to claim 8, wherein all remaining processing units of the corrugator follow the double facer with respect to the speed controller.

10. Method according to claim 8, wherein the double facer controls a web tension of the printed paper web on a last portion before the double facer.

11. Method according to claim 10, wherein the corrugator has a splicer which is arranged between the printing machine and the double facer, wherein the splicer has a measuring roller with which the web tension is measured in order to then be controlled by the double facer.

12. Method according to claim 1, wherein the printing machine is a digital printer.

13. System having a control unit designed to carry out a method according to claim 1.

Description

[0028] In the following, exemplary embodiments of the invention are explained in greater detail with reference to a drawing. The drawing shows schematically:

[0029] FIG. 1 a system,

[0030] FIG. 2 a cutout of the system from FIG. 1 in detail in a first operating mode,

[0031] FIG. 3 the cutout of the system according to FIG. 2 in a different operating mode.

[0032] FIG. 1 shows a highly simplified system 2 which has a corrugator 4 and a printing machine 6. The corrugator 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 unrolling 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 a single-sided corrugated cardboard web to a non-corrugated paper web to form a corrugated cardboard web 16, and the like.

[0033] 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. The term printed paper web is used to simplify the description of the paper web that passes through the printing machine 6 and is printed on by said printing machine.

[0034] In the exemplary embodiment shown, the printing machine 6 is a digital printer. An exemplary embodiment of the printing machine 6 can be seen in FIGS. 2 and 3, which each show portions of the system 2 in different operating modes. Of the corrugator 4, only an unwinder 10, a splicer 12, and a double facer 14 are shown in FIGS. 2 and 3, via which the printed paper web 18 is fed to the corrugator 4. The printing machine 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 unrolling and splicing unit E1 and forms an entrance of the printing machine 6. Downstream of this is an optional inlet tension 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 (inkjet printing cylinder) and printing bars 22 for printing a number of inks. Downstream of this, an optional varnishing E6 is carried out first, and downstream of this an optional digital printing varnishing E7 with a second, not explicitly shown, printing cylinder 20 (varnish printing cylinder) and printing bars 22.

[0035] The spatial arrangement of the printing machine 6 relative to the corrugator 4 is basically arbitrary; in FIG. 1, for example, the printing machine 6 is arranged parallel to the corrugator 4, wherein the printed paper web 18 is then introduced into the corrugator 4 via a number of turning bars 30. In FIGS. 2 and 3, only two turning bars 30 are shown as examples, 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 corrugator 4 via a combination of an unwinder 10 and a splicer 12, so that the printing machine 6 can optionally also be decoupled from the corrugator 4 and switched off, and then another paper web is fed to the corrugator 4 by means of the unwinder 10.

[0036] The system 2 has a speed controller 34 which specifies a speed of a lead machine for a number of follower machines so that they follow the lead machine. The speed is a conveying speed or a web speed, and then a speed of a respective paper web within the system 2, especially also the printed paper web 18 and the corrugated cardboard web 16 as a whole. The speed controller 34 specifies the overall speed of the lead machine as the target speed for the follower machines and controls these follower machines accordingly. In the present case, the printing machine 6 is the lead machine, and at least one of the processing units 8 of the corrugator 4 is a follower machine. In the present case, the corrugator 4 even follows the printing machine 6 completely, at least with respect to speed control.

[0037] The printing machine 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 using the speed controller 34. In the exemplary embodiment shown, the speed controller 34 also provides a virtual guide axis 36, which the printing machine 6, especially its printing cylinder 20, follows. In FIG. 1, a control unit 38 of the system 2 is shown, which contains the speed controller 34 with the virtual guide axis 36. In principle, it is possible for the control unit 38 to be integrated into the printing machine 6 or into the corrugator 4, or to be divided between them.

[0038] However, the virtual guide 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 needs to be changed when an order is changed and a corresponding speed is entered or set, the speed for the virtual guide axis 36 is changed, so that the corrugator 4 is then operated at a correspondingly changed speed.

[0039] The first printing cylinder 20 of the printing machine 6 follows the virtual guide 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 in the present case a part of the corrugator 4, i.e., the web tension of the various paper webs is controlled by means of a web transport control in the processing units 8 of the corrugator 4. At least the first printing cylinder 20 (inkjet printing cylinder) is excluded from this web transport control, but other portions of the printing machine 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 has been implemented for the entire system, in which the web tension is controlled on different portions of the system 2, but with the exception of the printing cylinder 20 in particular. This is controlled only by the speed controller 34, which the corrugator 4 then follows, so that the web transport control is also dependent upon the speed controller 34. This design is suitable for web transport, i.e., for conveying the paper web 18 through the system 2 during the production of a corrugated cardboard web 16. This web transport is a first operating mode of system 2 and is shown in FIG. 2.

[0040] In principle, the system 2 advantageously has, 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 runs into the corrugator 4 downstream of the printing machine 6. The roller pairs are marked in FIGS. 2 and 3 by arrows 44, wherein each arrow 44 begins at the measuring roller 42 of a roller pair and ends with the tip at the control roller 40 of the roller pair. For the sake of clarity, not all control rollers 40 and measuring rollers 42 have been explicitly provided with reference signs, but their position and function can be clearly seen from the arrows 44 and their course. The course of the arrows 44, i.e., their orientation either in the upstream direction or downstream direction, indicates the respective set control direction of the roller pair. As can be seen in the comparison of FIGS. 2 and 3, 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, and the respective measuring roller 42 is an undriven roller. Control rollers 40 used include, for example, cooling rollers 46, heating rollers, temperature-control rollers, press rollers, positioning rollers, or the previously mentioned printing cylinders 20. A wide variety of designs are suitable for the arrangement of the roller pairs along the paper web 18; a possible exemplary embodiment is shown in FIGS. 2 and 3.

[0041] In contrast to the web transport, the printing cylinders 20 are used for simply tensioning the paper web 18, especially the printing cylinder 20 of the printing unit E5 shown explicitly here, in order to control the web tension in the printing machine 6. In this case, the paper web 18 is only tensioned, and not conveyed. Tensioning is a second operating mode of the system 2, and an exemplary embodiment thereof is shown in FIG. 3. The measuring rollers 42 and control rollers 40 are basically arranged alternately along the printed paper web 18, such that a control roller 40 is located between two measuring rollers 42, and, vice versa, a measuring roller 42 is located between two control rollers 40. By changing the assignment of the measuring rollers 42 and control rollers 40 to each other in roller pairs, the control direction for web tension control can be changed. In FIGS. 2 and 3, all roller pairs upstream of the printing cylinder 20 shown have the same control direction during web transport and tensioning, i.e., upstream of the printing cylinder 20, the control direction remains unchanged. However, as can be seen in FIG. 3, from the printing cylinder 20 and downstream thereof, for tensioning, the control direction is reversed compared to the web transport in FIG. 2. For this purpose, a different measuring roller 42 is assigned to a respective control roller 40 (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 starting 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, a measuring roller 42 is then assigned to the respective control roller 40 upstream of the control roller 40, as shown in FIG. 3. This measuring roller 42 may have previously been the measuring roller 42 of another roller pair during web transport. In the present case, for tensioning purposes, all 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 control takes place on the whole in only one direction, towards the entrance of the printing machine 6. Based upon this, during web transport, the roller pairs from the printing cylinder 20 and downstream thereof are in the present case formed in such a way that the control roller 40 is located upstream of the associated measuring roller 42. As a result, the control takes place on the whole 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).

[0042] The corrugator 4 is controlled in the present case starting from the double facer 14. Accordingly, all other processing units 8 of the corrugator 4 follow the double facer 14 with respect to the speed controller 34. Since the double facer 14 now follows the printing machine 6, an additional adjustment of the web tension between the printing machine 6 and the corrugator 4 is required, because the speed of the double facer 14, which was not previously controlled, is now controlled in order to be adapted to the speed specified by the printing machine 6. This also applies quite generally if a processing unit 8 other than the double facer 14 was previously a master of the corrugator 4.

[0043] In order to adjust the web tension between the printing machine 6 and the corrugator 4, in the shown exemplary embodiment with the double facer 14, a web tension of the printed paper web 18 is controlled on a last portion 50 before the double facer 14. In this way, an adjustment of the speed when entering the corrugator 4 is realized. To control the web tension on the last portion 50, the system 2 has a pair of rollers, with a control roller 40 for adjusting the web tension on the last portion 50 and a measuring roller 42 for measuring the web tension on the last portion 42. In FIG. 2, the control roller 40 is part of the double facer 14.

[0044] As can be seen in FIG. 2, 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 portion 50 refers to the portion between the respective measuring roller 42 and the control roller 40. Although both of the described measuring rollers 42 are shown in FIG. 2, typically only one is used, depending upon whether the splicer 12 is present or absent.

LIST OF REFERENCE SIGNS

[0045] 2 system [0046] 4 corrugator [0047] 6 printing machine [0048] 8 processing units [0049] 10 unwinder [0050] 12 splicer [0051] 14 double facer [0052] 16 corrugated cardboard web [0053] 18 printed paper web [0054] 20 printing cylinder [0055] 22 printing bar [0056] 30 turning bar [0057] 34 speed controller [0058] 36 virtual guide axis [0059] 38 control unit [0060] 40 control roller [0061] 42 measuring roller [0062] 44 arrow (to mark a roller pair) [0063] 50 last portion [0064] E1 unwinding and splicing unit [0065] E2 inlet tension group [0066] E3 corona pretreatment [0067] E4 precoating [0068] E5 printing unit [0069] E6 varnishing [0070] E7 digital printing varnish