PRINTING MACHINE WITH A TWIN PRINTING UNIT AND METHOD OF OPERATING SUCH A PRINTING MACHINE

Abstract

A printing machine for printing on a printing substrate web includes a plurality of inline flexographic printing units which are disposed in a plane accessible to an operator of the machine. Each one of the two flexographic printing units of a respective duplex printing station includes a respective impression cylinder and a dryer disposed between the two impression cylinders along a path of web travel of the web of printing substrate. A method of operating the printing machine is also provided.

Claims

1. A printing machine for printing on a printing substrate web, the printing machine comprising: a plurality of inline flexographic printing units disposed in a plane accessible to a machine operator; every two of said flexographic printing units of said plurality of flexographic printing units together forming a duplex printing station; and each one of said two flexographic printing units of a respective duplex printing station including a respective impression cylinder and a dryer disposed between said impression cylinders of said two flexographic printing units along a path of web travel of the printing substrate web.

2. The printing machine according to claim 1, wherein said two flexographic printing units of a respective duplex printing station are jointly activatable and deactivatable or alternatively activatable and deactivatable.

3. The printing machine according to claim 1, wherein said two flexographic printing units of a respective duplex printing station are disposed mirror-symmetrically relative to said two impression cylinders.

4. The printing machine according to claim 1, wherein: said dryer disposed between said impression cylinders is one of between one and four dryers, or further dryers are each disposed downstream of a respective duplex printing unit.

5. The printing machine according to claim 4, wherein: said dryer disposed between said impression cylinders is a UV dryer or an IR dryer, or said further dryers are UV dryers or IR dryers.

6. The printing machine according to claim 4, wherein at least one of said impression cylinders of said two flexographic printing units of a respective duplex printing station is a temperature-controlled cylinder.

7. The printing machine according to claim 6, wherein a flexographic printing unit is disposed at a circumference of a respective temperature-controlled cylinder in every duplex printing station.

8. The printing machine according to claim 1, wherein each respective flexographic printing unit is equipped with an ink application device and a flexographic printing cylinder with a print sleeve carrying a printing forme.

9. The printing machine according to claim 1, wherein each respective impression cylinder has a radius smaller than 1000 mm.

10. The printing machine according to claim 1, which further comprises at least one further flexographic printing unit embodied as a single flexographic printing station or as a varnishing unit, in addition to said plurality of flexographic printing units.

11. The printing machine according to claim 10, wherein: said single printing station is disposed upstream of said plurality of flexographic printing units, or said single printing station is disposed downstream of said plurality of flexographic printing units.

12. The printing machine according to claim 10, wherein said single printing station is disposed downstream of said duplex printing station or downstream of a last duplex printing station in a direction of transport of the printing substrate web.

13. The printing machine according to claim 12, wherein: said single printing station has an impression cylinder constructed as a temperature-controlled cylinder having a circumference; and a flexographic printing unit, and one or two UV or IR dryers are disposed in succession at said circumference of said temperature-controlled cylinder in the direction of transport of the printing substrate web.

14. The printing machine according to claim 10, wherein: the printing machine includes sections and the printing substrate web runs at least one of: a) between two duplex printing stations, or b) between a duplex printing station or a last duplex printing station and said single printing station, in a second plane located below said plane in one or in all of said sections.

15. The printing machine according to claim 14, wherein the printing substrate web has a length in said one section or in all of said sections being smaller than a length of the printing substrate web in a duplex printing station.

16. The printing machine according to claim 14, wherein starting from said second plane, the printing substrate web forms a loop being downwardly open in every duplex printing unit.

17. The printing machine according to claim 16, which further comprises guide rollers disposed between said plane and said further plane, the printing substrate web loop running around one of said impression cylinders or around both of said impression cylinders and around at least two or three of said guide rollers.

18. The printing machine according to claim 1, wherein said duplex printing stations include a last duplex printing station, and a single printing station and a hot-air dryer are disposed downstream of said last duplex printing station in succession in a direction of transport of the printing substrate web.

19. The printing machine according to claim 1, wherein said dryer disposed between said two impression cylinders of a duplex printing station along the path of web travel of the printing substrate web is a hot air dryer or a UV dryer.

20. The printing machine according to claim 1, wherein said duplex printing stations include at least one duplex printing station with two impression cylinders and at least one duplex printing station with an impression cylinder being used by said two flexographic printing units.

21. The printing machine according to claim 20, wherein said duplex printing station with said impression cylinder being used by said two flexographic printing units includes a dryer disposed at a circumference of said impression cylinder being used by said two flexographic printing units.

22. A method of operating a printing machine to print on a printing substrate web, the method comprising: providing a printing machine according to claim 1; and activating and printing with a maximum of one flexographic printing unit at a time of said two flexographic printing units of a respective duplex printing station.

23. The method of operating a printing machine according to claim 22, which further comprises subjecting the other respective flexographic printing unit of the duplex printing station to set-up or maintenance operations.

24. The method of operating a printing machine according to claim 22, which further comprises activating the two flexographic printing units of a respective duplex printing station in an in-register manner and deactivating the two flexographic printing units of the respective duplex printing station.

25. The method of operating a printing machine according to claim 22, which further comprises activating at least one flexographic printing unit of a duplex printing station in an in-register manner and deactivating the at least one flexographic printing unit of the duplex printing station relative to another flexographic printing unit of the printing machine or relative to a treatment unit of the printing machine.

26. The method of operating a printing machine according to claim 25, which further comprises providing the treatment unit as an embossing unit or a die-cutting unit.

27. The method of operating a printing machine according to claim 22, which further comprises using a measuring device to measure printing forms and to transmit data obtained in the measurement to a duplex printing station at least one of for carrying out a flying change in an in-register manner or at an optimally preadjusted printing pressure in the duplex printing station.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0058] FIG. 1 is a diagrammatic, longitudinal-sectional view of a printing machine of the invention, namely a configuration including six DID stations followed by one SID station;

[0059] FIGS. 2A-2F are enlarged elevational views of a printing station of the printing machine shown in FIG. 1;

[0060] FIG. 3 is a longitudinal-sectional view of a web-fed printing machine in accordance with the prior art;

[0061] FIG. 4 is a group of elevational views illustrating the difference between a DID and an SID station;

[0062] FIG. 5 is an elevational view illustrating a DID station with two flexographic printing units that may be activated simultaneously;

[0063] FIG. 6 is an elevational view illustrating a DID station with two flexographic printing units that may be activated in an alternate way;

[0064] FIG. 7 is a longitudinal-sectional view illustrating a so-called a gable top application;

[0065] FIG. 8 is a longitudinal-sectional view illustrating a configuration with four SID stations followed by two DID stations;

[0066] FIG. 9 is a longitudinal-sectional view illustrating a configuration with four DID stations followed by four SID stations; and

[0067] FIG. 10 is an elevational view illustrating a duplex printing unit.

DETAILED DESCRIPTION OF THE INVENTION

[0068] Referring now to the figures of the drawings in detail and first, particularly, to FIG. 3 thereof, there is seen a prior art rotary printing machine 100 for printing on a printing substrate web 1. The printing substrate web 1 is transported through a plurality of treatment units in a direction of transport T for various treatments. The treatment tools are flexographic printing units 11 (unit 11a at the inlet and unit 11b at the outlet of the duplex printing unit), an embossing unit 12, and a die-cutting and creasing unit 13. Inspection systems 14, for instance embodied as cameras for continuously monitoring the in-register treatment of the printing substrate web 1, are disposed next to the web path of the printing substrate web 1. The systems in particular monitor the circumferential and lateral registers. Inspection systems 14, flexographic printing units 11, embossing unit 12, and die-cutting and creasing unit 13 are connected to a control unit 22 by data transmission lines and may be actuated by the control unit 22.

[0069] FIG. 1 is an overall representation of a printing machine 100. The printing machine 100 of the invention includes a plurality of flexographic printing units 11. The flexographic printing units 11 print on a printing substrate web 1 that is transported in a direction of web transport T. The flexographic printing units 11 have been numbered as DW1 to DW7. The flexographic printing units 11 are in an inline configuration on a plane E that is easily accessible to a machine operator. Two flexographic printing units 11 together form a printing station 10, at least in printing stations DW1 to DW6, which may be referred to as a twin printing unit (or as duplex printing stations or DID). The printing station DW7 is embodied as a conventional flexographic printing unit 11 (also referred to as a single printing station or SID), which may, for instance, apply a continuous layer of varnish. The first printing station 10 DW1 applies the color magenta, the second printing station 10 DW2 applies the color cyan, the third printing station 10 DW3 applies the color yellow, and the sixth printing station DW6 applies the color black. The further printing stations 10 DW4/DW5 apply special colors S1 and S2.

[0070] A dryer 19 is provided downstream of every printing station 10 in the direction of web travel T.

[0071] As shown in the printing machine 100 in FIG. 3, an embossing unit 12, a die-cutting and creasing unit 13, and a control unit 22 may be provided in addition to the flexographic printing units 11.

[0072] The construction of a respective printing station 10 will be shown in more detail in FIGS. 2A-F.

[0073] FIGS. 2C and 2D illustrate a printing substrate web 1 guided by deflection rollers 20 in a direction of web transport T and wrapping around an impression cylinder 16. Two flexographic printing units 11, each one of which includes a flexographic printing cylinder with a printing sleeve 15, an impression cylinder 16, and an ink application device 21, form a printing station 10. The flexographic printing units 11 with their components are disposed in a plane E. The two flexographic printing units 11 have a common impression cylinder 16. The configuration of flexographic printing cylinders 15 and ink application device 21 of the two flexographic printing units 11 is mirror-symmetrical to a vertical axis of reflection which passes through the impression cylinder 16. The printing station 10 is constructed in such a way that one of the two flexographic printing units 11 prints and is in an active position. The other, inactive flexographic printing unit 11 has been disengaged from the common impression cylinder 16. An activation or deactivation of a flexographic printing unit 11 is achieved by an adjustment movement s. In the illustrations of FIG. 1 and FIGS. 2C-D, a first print job is being processed in the respective right-hand flexographic printing units 11 of a respective printing station 10. At the same time, a second print job may be prepared or maintenance work, such as a blade change at the doctor blade, may be carried out in the left-hand flexographic printing unit 11 of the printing stations 10. When a first job has been completed at a specific point in time, the right-hand flexographic printing unit 11 automatically moves into an inactive stand-by position and the left-hand flexographic printing unit 11 simultaneously moves into an active position to print the second print job. Thus, the completion of a first print job and the beginning of a second, subsequent print job are practically simultaneous. This process, which has been described in the context of a first printing station 10, is implemented in the further printing stations 10 in the same way at the same location, i.e. the second printing station 10 is switched from the first print job to the second and thus from the right-hand flexographic printing unit 11 to the left-hand flexographic printing unit 11 at precisely the location of the printing substrate web 1 where the first printing station 10 was switched over. This reduces unusable products, i.e. waste. In other words, the flexographic printing units 11 of the various printing stations 10 synchronize with one another in an in-register way, resulting in virtually no waste.

[0074] The switch from one print job to the next print job is made in an event-driven way. The triggering event may be a specified printing time, a specified length of the web of substrate that has been printed, a specified number of printed copies, a change of material, or an initiating operation by the machine operator. Due to such an event-driven control of the printing machine 100 by using a control unit 22, the printing machine 100 is capable of preparing for the next print jobs while processing a current print job and may successively process the next print jobs.

[0075] A dryer 19a, preferably a hot-air dryer 19a, is disposed at the circumference of the common impression cylinder 16. This dryer preferably acts as an intermediate dryer. In addition, a dryer 19 is provided. This dryer preferably acts as a final dryer.

[0076] As compared to FIGS. 2C and 2D, FIGS. 2A and 2B illustrate an embodiment which includes two impression cylinders 16a and 16b instead of the common impression cylinder 16. The web 1 is guided on a web path 1a between the two impression cylinders 16a and 16b, preferably in a horizontal direction. The dryer 19a is disposed at the web path 1a instead of at the common impression cylinder 16. The dryer preferably acts as an intermediate dryer. In addition, a dryer 19 is provided. This dryer preferably acts as a final dryer.

[0077] Alternatively, a dryer system with one or two fixed UV dryers or changeable drying systems, for instance IR or hot air dryers, may be provided at a location between the two impression cylinders 16 where the web 1 is preferably guided in a horizontal direction on the web path 1a. The dryer(s) is/are preferably used as intermediate dryers. In addition, a dryer 19 is provided, which preferably acts as a final dryer.

[0078] FIG. 2B illustrates a (pre-)conditioning unit 50, which may advantageously be used to condition/precondition the web before it enters the first printing unit, in particular to bring its temperature up to an operating temperature and/or to shrink the web. This may avoid register problems because if this is done, the web has been preshrunk and/or its temperature has been adjusted before the first printing unit as much as it would otherwise not have been until after the second printing unit/the downstream dryer.

[0079] As compared to FIGS. 2A and 2B, FIGS. 2E and 2F once again illustrate an embodiment which includes a common impression cylinder 16. In this case, a UV dryer 19a is disposed at the circumference of the common impression cylinder. This dryer preferably acts as an intermediate dryer. In addition, a UV dryer 19 is provided, which preferably acts as a final dryer.

[0080] FIG. 4 illustrates the difference between a DID station 31 (on the left-hand side of the figure) and an SID station 30 (on the right-hand side of the figure). Such stations may be provided in the configurations shown in the present application (see FIG. 7, for instance).

[0081] Both stations are embodied as so-called short web stations: if UV inks are used, the dryer section may be chosen to be much shorter; UV dryers may in particular be disposed on the circumference of a (central) impression cylinder or between two impression cylinders in a space-saving way. Compared to thermal drying of water-based or solvent-based inks (see FIGS. 1, 8, and 9, for instance), the drying section is much shorter. The path of web travel between the stations may additionally be in a plane below the plane E which is accessible to the operator of the machine. The web is thus guided to the stations from below. The short web path between the stations results in an improved register behavior. In addition, the process of starting up the printing machine is shortened to a considerable extent. The (central) impression cylinder/the two impression cylinders is/are preferably embodied as (a) temperature-controlled cylinder(s), in particular as a cooling cylinder.

[0082] The DID station 31 includes the following elements in the direction of printing substrate transport: a deflection roller 20 for the web 1, a central impression cylinder 16, a first flexographic printing unit 11 assigned to the latter (and including a flexographic printing cylinder 15 and an ink application device 21 such as an anilox cylinder), one or (as illustrated) two dryers 19, a second flexographic printing unit 11, one or (as illustrated) two further dryers 19, and two deflection rollers 20. The dryers are preferably UV dryers. Such a station is capable of applying two colors at the same time.

[0083] Alternatively, the DID station 31 may include the following in the direction of printing substrate transport: a deflection roller 20 for the web 1, two impression cylinders 16, a first flexographic printing unit 11 assigned to the latter (and including a flexographic printing cylinder 15 and an ink application device 21 such as an anilox cylinder), one or (as illustrated) two dryers 19, a second flexographic printing unit 11, one or (as illustrated) two further dryers 19, and two deflection rollers 20. The dryers are preferably UV dryers or IR dryers. Such a station is capable of applying two colors at the same time.

[0084] The SID station 30 includes the following elements in the direction of printing substrate transport: preferably two deflection rollers 20 for the web 1, an impression cylinder 16, a flexographic printing unit 11 assigned to the latter (and including a flexographic printing cylinder 15 and an ink application device 21 such as an anilox cylinder), one or (as illustrated) two dryers 19a, 19b, and preferably a deflection roller 20. The dryers are preferably UV dryers. Such a station is capable of applying one color.

[0085] FIG. 5 illustrates a DID station with two flexographic printing units 11 that are simultaneously activatable. One or (as shown) two dryers 19 are disposed downstream of every flexographic printing unit 11 at the (central) impression cylinder 16. The dryers are preferably UV dryers.

[0086] Alternatively, a DID station with two simultaneously activatable flexographic printing units 11 with two impression cylinders 16 may be provided; in this case, one dryer 19 or two dryers 19 is/are provided downstream of every flexographic printing unit 11. The dryers are preferably UV or IR dryers.

[0087] FIG. 6 illustrates a DID station with two flexographic printing units 11 that are alternately activatable. One or (as shown) two dryers 19 are disposed downstream of the last flexographic printing unit 11 at the (central) impression cylinder 16. The dryers are preferably UV dryers.

[0088] Alternatively, the DID station with two alternatingly activatable flexographic printing units 11 may be provided; in this case, one or two dryers 19 are disposed downstream of the last one of the two flexographic printing units 11. The dryers are preferably UV or IR dryers.

[0089] FIG. 7 illustrates a further application, namely a machine with four DID short web stations 31 and an SID station 30 as well as a final thermal dryer 19. Eight colors and a varnish or silicone may be applied. A web-guiding element 40 is provided between the last station 31 and the station 30. Such a configuration is used, for instance, to produce so-called gable top packaging. As an alternative to the illustrated embodiment, each printing unit may include two impression cylinders.

[0090] FIG. 8 illustrates a configuration including four SID stations 30 followed by two DID stations 31. Every station is assigned a thermal dryer 19. The web is guided to the stations from above. The printing sequence may be as follows: CMYK process colors, special color 1, special color 3. The special color units may be changed to other special colors 2 and 4 while the production run continues.

[0091] FIG. 9 illustrates a configuration including four DID stations 31 followed by four SID stations 30. Every station is assigned a thermal dryer 19. The web is guided to the stations from above. The printing sequence may be as follows: CMYK process colors, special color 1, special color 2. The two last stations 30 are inactive and are prepared for a following print job or other changes are made (special colors 3 and 4).

[0092] Instead of what is shown in FIG. 1, the printing machine 100 shown in FIG. 1 may have the following construction: at least one duplex printing station 10 (preferably corresponding to FIGS. 2A to 2F, i.e. including two impression cylinders) and at least one single printing station 11 (preferably corresponding to the right-hand section of FIG. 4). Any desired combinations and sequences are possible. FIG. 8 (four SID and two DID) and FIG. 9 (four DID and four SID) illustrate respective variants: the duplex printing units with common impression cylinders shown therein would have to be replaced by duplex printing units with two impression cylinders. In addition, one or more SID unit(s) and/or one or more DID unit(s) without dryers may be provided at the impression cylinder.

[0093] FIG. 10 illustrates a duplex printing unit with two impression cylinder 16a and 16b spaced apart from one another. A printing cylinder 15 and an anilox roller 21 are associated with the first impression cylinder 16; a further printing cylinder 15 and a further anilox roller 21 are associated with the second impression cylinder 16b. Two dryers 19a and 19b are disposed between the two impression cylinders along the path of the printing substrate web. Two further dryers 19c and 19d are provided downstream of the second impression cylinder 16b along the path of the printing substrate web. Within the duplex printing unit, the web path follows a loop which is open towards the bottom.

[0094] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0095] 1 printing substrate web [0096] 1′ loop [0097] 1a path of web travel [0098] 10 printing station [0099] 11 flexographic printing unit [0100] 11a flexographic printing unit (inlet of a duplex printing station) [0101] 11b flexographic printing unit (outlet of a duplex printing station) [0102] 12 embossing unit [0103] 13 die-cutting and creasing unit [0104] 14 inspection system [0105] 15 flexographic printing cylinder with printing sleeve [0106] 16 common impression cylinder [0107] 16a impression cylinder [0108] 16b impression cylinder [0109] 17 embossing cylinder [0110] 18 die-cutting cylinder [0111] 19 dryer [0112] 19a, b, c, d dryer [0113] 20 deflection roller [0114] 21 ink application device [0115] 22 control unit (machine control unit with interface) [0116] 30 SID station (single ink deck) [0117] 31 DID station (double ink deck) [0118] 40 web path [0119] 50 (pre)conditioning unit [0120] 100 printing machine [0121] s adjustment movement [0122] E plane [0123] F second plane [0124] T direction of web transport [0125] DW printing unit number [0126] M magenta [0127] C cyan [0128] Y yellow [0129] K black [0130] S1, S2 special colors