EP3431291B1 - Printing machine with a plurality of in-line flexographic printing units and method for operating such a printing machine - Google Patents

Description

The invention relates to a printing machine according to the preamble of claim 1 and a method for operating such a printing machine having the features of claim 14.

State of the art

Increasingly high demands are being placed on printing presses designed or used for packaging printing in terms of cost-effectiveness and ease of operation while at the same time maximizing variability for product manufacture. For example, the printing press should cause as little waste as possible, for example when changing over between different print jobs. Common in-line web printing machines designed for packaging printing, especially flexographic printing, usually have a machine design in which a substrate is guided over a large number of cylinders and rollers between different process levels (e.g. for printing and for drying), so that a no insignificantly long web section is stored in the printing press and potentially corresponding waste can occur.

In order to produce folding box blanks, inline machines for printing and rotary die-cutting of box blanks are known, for example from EP 1 731 277 B1 . In this case, a web-shaped substrate is printed in a web printing machine with a plurality of printing units, possibly using different printing methods. The web of printing material is then further processed by punching, embossing, varnishing, etc.

From the DE 103 43 411 B4 is a rotary printing machine known with a plurality of printing units, wherein the printing units for a quick job change with so-called sleeves can be fitted. For this purpose, the axes of the sleeves can be moved into a changing position by motor, in which the axes are easily accessible. After the sleeves have been changed, they are moved back together with their axes from an exchange position to an operating position.

the EP2551078A1 discloses - according to the preamble of claim 1 - a printing machine for printing a printing material web with a plurality of flexographic printing units arranged in a row, the flexographic printing units being arranged in a plane accessible to the machine operator.

the EP0234456A2 discloses an additional printing unit, for example an additional flexographic printing unit. In this case, two pressure cylinders are provided for receiving the printing plates, which are used alternately and selectively to create additional impressions in a paper web or similar material that is moved around a common impression cylinder. These additional printing devices are mostly used in rotary printing machines, where such additional devices are arranged at the outlet of the main machine. The main engine is not described in detail. the US5503069A1 reveals similar.

A disadvantage of the printing presses known from the prior art is that changing the sleeves requires a break in printing, with the downtime reducing the performance of the printing press. If a color change is required, longer downtimes are required. Furthermore, every time the machine stops, there is start-up waste, i.e. printed substrate web, which is scrap.

task

It is therefore the object of the present invention to create a printing machine which enables a simple and rapid job change while producing as little waste as possible and to describe a method for operating such a printing machine.

Technical solution

This object is achieved by a printing machine having the features of claim 1 and by a method having the features of claim 14.

A printing machine according to the invention for printing a printing material web with a plurality of flexographic printing units arranged in a row, with the flexographic printing units being arranged in a plane accessible to the machine operator, is characterized in that two flexographic printing units of the plurality of flexographic printing units together form respective double printing stations and that the two flexographic printing units of the respective double printing stations have a common impression cylinder.

The printing machine according to the invention serves to print a printing material web, in particular made of paper, cardboard or plastic, and has a plurality of flexographic printing units arranged in a row. Due to the in-line design, the printing machine can be expanded as required. The flexographic printing units are arranged in a plane that is accessible to a machine operator, in particular a horizontal plane, at an ergonomically easily accessible height level.

According to the invention, two flexographic printing units together always form a double printing station. The two flexographic printing units of a printing station each have a common impression cylinder. This structure of a printing station can be referred to as a twin printing unit or so-called double ink deck, DID, in contrast to the so-called single ink deck, SID.

It is preferred that the two flexographic printing units of a respective double printing station can be activated alternatively. This enables continuous production, i.e. a flying order change. As an alternative to this, the two flexographic printing units of a respective double printing station can be activated together.

In an advantageous development of the printing machine according to the invention, the two flexographic printing units of a respective double printing station are mirror-symmetrical to the common impression cylinder arranged. While printing is in one flexo printing unit, the other flexo printing unit can be set up or serviced.

In a particularly advantageous and therefore preferred embodiment, each double printing station is followed by a dryer. This has the advantage that after the application of ink, the applied amount of ink can be completely dried and the web of printing material can be deflected without any problems, without smearing occurring. Alternatively, it is provided that each double printing station includes at least one dryer, preferably two or four dryers.

It is also preferred that the dryer is a UV dryer or that the dryers are UV dryers. It is also preferred that the common impression cylinder of a respective double printing station is designed as a cooling cylinder.

In a particularly advantageous and therefore preferred embodiment, it is provided that in each double printing station on the circumference of the cooling cylinder in the direction of transport of the printing material, the following are arranged one after the other: a flexographic printing unit; one or two UV dryers; a flexographic printing unit; and one or two UV dryers.

It is also advantageous if a respective flexographic printing unit is equipped with an inking device and with a flexographic printing cylinder with a printing sleeve carrying the printing form.

In practice, it has proven to be advantageous if a respective impression cylinder has a circumference of less than 1000 mm (in the case of hot-air drying).

In a particularly advantageous and therefore preferred embodiment, it is provided that, in addition to the plurality of flexographic printing units, there is at least one further flexographic printing unit as an individual printing station, preferably as a varnishing unit.

In a particularly advantageous and therefore preferred embodiment, it is provided that the individual printing station is arranged in front of the plurality of flexographic printing units or that the individual printing station is arranged after the plurality of flexographic printing units.

In a particularly advantageous and therefore preferred embodiment, it is provided that the single printing station is arranged downstream of the double printing station—or a last double printing station—in the printing material transport direction.

In a particularly advantageous and therefore preferred embodiment, it is provided that the impression cylinder in the individual printing station is designed as a cooling cylinder and that the following are arranged one after the other on the circumference of the cooling cylinder in the printing material transport direction: a flexographic printing unit; and one or two UV dryers

In a particularly advantageous and therefore preferred embodiment it is provided that the printing material on a section - or on all sections - a) between two double printing stations and / or b) between the double printing station - or a last double printing station - and the Single printing station runs in a second level, which is substantially below the level.

In a particularly advantageous and therefore preferred embodiment, it is provided that the length of the web of printing material on the section—or on all sections—is less than the length of the web of printing material in a double printing station.

In a particularly advantageous and therefore preferred embodiment, it is provided that the printing material web forms a downwardly open loop starting from the second level in each double printing unit.

In a particularly advantageous and therefore preferred embodiment, it is provided that the loop runs around the impression cylinder and around at least two or three guide rollers, which is or are arranged between the plane and the further plane.

In a particularly advantageous and therefore preferred embodiment, it is provided that the last double printing station is followed in succession by a single printing station and a hot-air dryer in the printing material transport direction.

The invention also relates to a method for operating a printing press, as described above, for printing a printing material web. According to the invention, a maximum of one flexographic printing unit of the two flexographic printing units of a respective double printing station is activated and prints onto the printing material web. The respective other flexographic printing unit, i.e. the inactive printing unit, can advantageously be subjected to a double printing station, a set-up process or a maintenance process, or it is in an inactive waiting position. During a set-up process, for example, print sleeves can be exchanged or colors can be changed. Special colors can also be easily used and exchanged. The maintenance process can be, for example, a blade change on the squeegee. In a particularly advantageous and therefore preferred development of the method according to the invention, the flexographic printing units of a respective double printing station can be activated and deactivated with register accuracy in order to enable a flying change between the flexographic printing units when changing jobs. This means that when there is a job changeover, there should be a switchover from one flexo printing unit to the other flexo printing unit in a printing station, so the flexo printing units of the various printing stations are synchronized with one another in such a way that no waste is produced between the jobs and the printing material can continue to be printed on continuously.

The invention described and the advantageous developments of the invention described also represent advantageous developments of the invention in combination with one another - insofar as this is technically sensible.

With regard to further advantages and configurations of the invention that are advantageous in terms of construction and function, reference is made to the subclaims and the description of exemplary embodiments with reference to the accompanying figures.

example

The invention will be explained in more detail using the attached figures. Corresponding elements and components are provided with the same reference symbols in the figures. For the sake of better clarity of the figures, a true-to-scale representation has been dispensed with.

It show in schematic representation

1

a printing machine according to the invention or a configuration with six DID stations followed by one SID station;

2

a printing station of the printing press 1 ;

3

a prior art web printing machine;

4

the difference between a DID and a SID station;

figure 5

a DID station with two flexographic printing units that can be activated simultaneously;

6

a DID station with two flexographic printing units that can be activated alternately;

7

a so-called gable top application;

8

a configuration with four SID followed by two DID stations; and

9

a configuration with four DID followed by four SID stations.

figure 3 shows a rotary printing machine 100 according to the prior art for printing a printing material web 1. The printing material web 1 is transported in the transport direction T through a plurality of processing units and processed in the process. The processing tools are flexographic printing units 11, an embossing unit 12 and a punching and creasing unit 13. Inspection systems 4 are provided adjacent to the path of the printing material web 1, which are designed as cameras, for example, in order to continuously improve the register accuracy of the processing of the printing material web 1 monitor. In particular, the circumferential register and the lateral register are monitored.

The inspection systems 4 and the flexographic printing units 11, embossing unit 12 and punching and creasing unit 13 are connected to a control unit 22 for data transmission and can be controlled by the same.

figure 1 shows a printing machine 100 in an overview. The printing press 100 has a plurality of flexographic printing units 11 . A printing material web 1 moving in the web transport direction T is printed with the flexographic printing units 11 . The flexographic printing units 11 are numbered consecutively with DW1 to DW7. The flexographic printing units 11 are arranged in a row on a horizontal level E that is easily accessible for a machine operator. Two flexographic printing units 11 together form a printing station 10, at least in DW1 to DW6, which can also be referred to as a twin printing unit. The DW7 is designed as a conventional flexographic printing unit 11 . In this, for example, a flat application of paint can take place. The color magenta is printed in the first printing station 10 DW1, the color cyan is printed in the second printing station 10 DW2, the color yellow is printed in the third printing station 10 DW3 and the color black is printed in the sixth printing station DW6. Special colors S1 and S2 are printed in the further printing stations 10 DW4 and DW5.

A dryer 19 is provided after each printing station 10, viewed in the direction of web travel T.

In addition to the flexographic printing units 11 can - as well as in the printing press 100 from figure 3 - An embossing unit 12, a punching and creasing unit 13 and a control unit 22 may be provided.

The structure of a respective printing station 10 is described in more detail in figure 2 shown. A printing material web 1 transported in web transport direction T is guided with the aid of deflection rollers 20 and wraps around an impression cylinder 16. Two flexographic printing units 11, each with a flexographic printing cylinder with printing sleeve 15, an impression cylinder 16 and an inking device 21, form a printing station 10. The flexographic printing units 11 with their components are arranged in a plane E. The two flexographic printing units 11 have a common impression cylinder 16. The arrangement of flexographic printing cylinders 15 and inking device 21 of the two flexographic printing units 11 is mirror-symmetrical to a vertical mirror axis through the impression cylinder 16. The printing station 10 is designed in such a way that one of the two flexographic printing units 11 prints and this flexographic printing unit 11 is in an activated position. The other, inactive flexographic printing unit 11 was shared Impression cylinder 16 turned off. The activation or deactivation of a flexographic printing unit 11 is effected by an actuating movement s figure 1 and figure 2 a first print job is processed in the right flexographic printing units 11 of a respective printing station 10. At the same time, a second job can be prepared in the left-hand flexographic printing unit 11 of the printing stations 10, or this flexographic printing unit 11 can be serviced, for example a blade change can be carried out on the squeegee. If a first order has been processed at a certain point in time, the right flexographic printing unit 11 automatically moves into an inactive waiting position and at the same time the left flexographic printing unit 11 moves into an active position in order to print the second order. The end of printing of a first print job and the start of printing of a second, subsequent print job are therefore almost at the same time. This process, which has been described for a first printing station 10, also takes place in the other printing stations 10, precisely for the stretch, ie in the second printing station 10 the switchover from the first to the second order takes place and thus the switchover from the right flexographic printing unit 11 to the left flexographic printing unit 11 exactly at the point of the printing substrate web 1 where the first printing station 10 has completed the change. Waste, ie waste, can thus be saved. In other words: the flexographic printing units 11 of the various printing stations 10 are synchronized with register accuracy when there is a job change, so that there is almost no waste.

The change from one print job to a subsequent print job is event-driven. The triggering event can be a specific printing time, a specific printed length on the substrate web, a specific number of printed copies, a change of material or a trigger by the machine operator. With such an event-driven control of the printing machine 100 by means of a control unit 22, the printing machine 100 is able to simultaneously prepare next print jobs while a current print job is being processed and to process them in sequence.

figure 4 shows the difference between a DID station 31 (on the left in the figure) and a SID station 30 (on the right in the figure). Such stations can, in the configurations shown in this application (see e.g figure 7 ) be provided.

Both stations are designed as so-called "short web" stations: When printing UV inks, the drying section can be much shorter. In particular, UV dryers can be arranged on the circumference of a (central) impression cylinder to save space. Compared to the thermal drying of water-based paints (see e.g figures 1 , 8th and 9 ) the dryer section is significantly shorter. The web guide between the stations can also take place on a level below level E, which is accessible to the machine operator. The web is thus guided "from below" to the stations. The short path between the stations ensures improved register behavior. The start-up process for the printing press is also significantly shorter. The (central) impression cylinder is preferably designed as a cooling cylinder.

The DID station 31 comprises the following in the direction of the printing material transport: a deflection roller 20 for the web 1, a central impression cylinder 16, assigned to this a first flexographic printing unit 11 (with flexographic printing cylinder 15 and inking device 21, e.g. a screen cylinder), one or (like shown) two dryers 19, a second flexographic printing unit 11, one or (as shown) two further dryers 19 and two deflection rollers 20. The dryers are preferably UV dryers. Such a station can transmit two colors at the same time.

The SID station 30 comprises the following in the direction of the printing material transport: two deflection rollers 20 for the web 1, a central impression cylinder 16, assigned to this a first flexographic printing unit 11 (with flexographic printing cylinder 15 and inking device 21, e.g. a screen cylinder), one or (like shown) two dryers 19 and a deflection roller 20. The dryers are preferably UV dryers. Such a station can transmit one color.

figure 5 shows a DID station with two flexographic printing units 11 that can be activated simultaneously. On the (central) impression cylinder 16, one or (as shown) two dryers 19 are arranged after each flexographic printing unit 11. The dryers are preferably UV dryers figure 6 shows a DID station with two flexographic printing units 11 that can be activated alternately. One or (as shown) two dryers 19 are arranged on the (central) impression cylinder 16 after the last flexographic printing unit 11 . The dryers are preferably UV dryers.

figure 7 shows another application. This is a machine with 4 DID short web stations 31 and one SID station 30 and a final thermal dryer 19. Eight colors and a lacquer or silicone can be applied. A web guide 40 is provided between the last station 31 and the station 30 . Such an application is used, for example, in the production of so-called "gable top" packaging.

figure 8 shows a configuration with four SID stations 30 followed by two DID stations 31. A thermal dryer 19 is associated with each station. The web is guided "from above" to the stations. The printing sequences can be: CMYK process colors, spot color 1, spot color 3. The spot color units can be converted to other spot colors 2 and 4 during ongoing production.

figure 9 shows a configuration with four DID stations 31 followed by four SID stations 30. A thermal dryer 19 is associated with each station. The web is guided "from above" to the stations. The printing sequences can be: process colors CMYK, spot color 1, spot color 2. The last two stations 30 are inactive and are prepared or converted, for example, for an upcoming print job (spot colors 3 and 4).

Reference List

1

substrate web

10

printing station

11

flexographic printing unit

12

embossing plant

13

Stamping and creasing unit

14

inspection system

15

Flexo printing cylinder with printing sleeve

16

Impression cylinder

17

embossing cylinder

18

punch cylinder

19

dryer

20

pulley

21

paint application device

22

Control unit (machine control with interface)

30

SID Station (Single Ink Deck)

31

DID Station (Double Ink Deck)

40

web guidance

100

printing press

s

actuating movement

E

level

T

web transport direction

DW

printing unit number

M

magenta

C

cyan

Y

Yellow

K

Black

S1, S2

special colours

Claims (16)

1. Printing machine (100) for printing on a web (1) of printing material, the printing machine comprising a plurality of in-line flexographic printing units (11) disposed in a plane (E) accessible to a machine operator and
   characterized
   in that every two flexographic printing units (11) of the plurality of flexographic printing units (11) together form double printing stations (10) and in that the two flexographic printing units (11) of a respective double printing station (10) have a common impression cylinder (16).
2. Printing machine according to claim 1,
   characterized
   in that the two flexographic printing units (11) of a respective double printing station (10) are jointly activatable or alternately activatable.
3. Printing machine according to any one of the preceding claims,
   characterized
   in that the two flexographic printing units (11) of a respective double printing station (10) are disposed mirror-symmetrically relative to the common impression cylinder (16).
4. Printing machine according to any one of the preceding claims,
   characterized
   in that a drier (19) is disposed downstream of every double printing station (10) or in that every double printing station (10) comprises at least one drier (19) or two driers or four driers.
5. Printing machine according to claim 4,
   characterized
   in that the drier (19) is a UV drier/the driers (19) are UV driers.
6. Printing machine according to claim 4 or 5,
   characterized
   in that the common impression cylinder (16) of each respective double printing station (10) is embodied as a cooling cylinder (16).
7. Printing machine according to claim 6,
   characterized
   in that in every double printing station (10),

   - a flexographic printing unit (11),

   - one or two UV driers (19),

   - a flexographic printing unit (11), and

   - one or two other UV driers (19) are disposed along the circumference of the cooling cylinder to succeed one another in a direction of web transport.
8. Printing machine according to any one of the preceding claims,
   characterized
   in that each respective flexographic printing unit (11) is equipped with an ink application device (21) and a flexographic printing cylinder (15) with a printing sleeve carrying the printing forme.
9. Printing machine according to any one of the preceding claims,
   characterized
   in that each respective impression cylinder (16) has a circumference smaller than 1000 mm.
10. Printing machine according to any one of the preceding claims,
    characterized
    in that in addition to the plurality of flexographic printing units (11), at least one further flexographic printing unit (11) is provided, the at least one further flexographic printing unit being a single printing station (10) or a varnishing unit (10).
11. Printing machine according to claim 10,
    characterized
    in that the single printing station (10) is disposed upstream of the plurality of flexographic printing units (11) in the direction of web transport (T) or in that the single printing station (10a) is disposed downstream of the plurality of flexographic printing units in the direction of web transport (T).
12. Printing machine according to claim 11,
    characterized
    in that in the single printing station (10a), the impression cylinder (16) is embodied as a cooling cylinder (16) and in that a flexographic printing unit (11) and one or two UV driers are disposed along the circumference of the cooling cylinder so as to succeed one another in the direction (T) of web transport.
13. Printing machine according to any one of the preceding claims,
    characterized
    in that a single printing station (10a) and a hot-air drier are disposed downstream of the last double printing station (10) so as to succeed one another in the direction (T) of web transport.
14. Method for operating a printing machine (100) for printing on a web of printing material according to any one of the preceding claims, wherein a printing machine (100) according to any one of the preceding claims is provided and a maximum of one flexographic printing unit (11) of the two flexographic printing units (11) of a respective double printing station (10) of the printing machine (100) is activated and printing.
15. Method for operating a printing machine according to claim 14,
    wherein the other flexographic printing unit (11) of a double printing station (10) is subjected to a set-up operation or to a maintenance operation.
16. Method for operating a printing machine according to any one of claims 14 or 15,
    characterized
    in that the two flexographic printing units (11) of a respective double printing station (10) are activatable and deactivatable in an in-register way.

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