ES2864766T3 - Procedure and device for printing a printing support strip inside a rotary printing machine - Google Patents

Abstract

Procedure for printing a printing support strip (7) inside a rotary printing machine (1), wherein - with at least one printing roller (5) a printing pattern is applied to the printing support strip (7), wherein the printing roller (5) rotates with a peripheral speed, - by means of at least one measuring device (20) housed inside the rotary printing machine (1) a printing length is measured, and wherein the measurement of the print length is performed before the print support band (7) reaches the print roller (5), where with the measuring facility (20) the print length of a printing motif that is already at the rear of the printing support strip (7) characterized in that the peripheral speed of the at least one printing roller (5) is changed if the measured printing length varies by a length of theoretical impression, where the tensions print media band (7) are not affected.

Description

DESCRIPTION

Procedure and device for printing a printing support strip inside a rotary printing machine

The invention relates to a method and a device for printing a print support web inside a rotary printing machine.

In rotary printing machines, in which a print pattern is repeatedly applied to a print carrier web, print patterns are applied by a print roller. The print carrier strip in this case runs over a print cylinder. The peripheral speeds of the printing roller and the printing cylinder are in this case the same.

However, it is problematic that within the print carrier web the web tensions can be considerably different. This can cause the printing lengths on the finished printed media strip to be different as well, which often in the case of post-processing of such printed strips leads to disadvantages. Print length is the distance between two equal points within two consecutive print patterns. These can be for example the registration points. If, for example, in a second printing process the backside of an already printed media strip is to be printed as well, then in the case of the print motif on the front there should be no variation compared to the print motif at the rear in terms of print length.

According to the state of the art, the position of the print on the unwound web of material is corrected by correction of the web tension by means of the preference adjusted to the web tension over the printing roller in such a way that the support web The printing plate is stretched to a constant printing length as the material is influenced in its stretching, regardless of the measured printing length, with a higher or lower web tension in order to supply the printing roller with a printing support strip, which It has both a constant pattern repeat length, which corresponds to the print length of the new print as well as the position of the new print.

US 3 559 568 describes a method for adjusting the print length to a theoretical print length, wherein the printed print length is measured and in case of a variation the printed print length is adjusted to reduce the variation. The measurement is therefore carried out behind the printing mechanism and is not compared with a motif already printed on the back.

US 2006/0016359 A1 deals with the problem that during storage a printed roll changes an actual length. These changes are modeled and corresponding to this model the print length is varied. The print lengths are also measured and compared to the theoretical print length. The print length is adjusted accordingly by the prediction model.

DE 195 47 074 A1 deals with the printing of a tubular packaging medium. To achieve registration security during backside printing, marks are printed with an invisible UV ink, which serve to create the registration. Therefore registration marks are necessary. Accordingly, document DE 195 47 074 A1 discloses a method according to the preamble of claim 1 and a corresponding printing machine for carrying out the same.

The disadvantages of this method are that the influence on the pattern repeat length correction is limited by the change in web tension. The web tension cannot be arbitrarily low to achieve a reduction in pattern repeat length, as minimal web tension is always required to safely circulate the web of material through the machine. The web tension should not be arbitrarily high to achieve elongation of the repeat pattern captures, as too high web tensions can durably change the media by causing long-lasting plastic deformation, if the limit is exceeded elastic typical of the material.

Furthermore, the hitherto known methods are only suitable for working with essentially elastic printing substrates such as plastic foils. For rigid materials, such as paper or aluminum foil, it is not sensible to use these, as by varying the web tension before printing there will hardly be any influence on the pattern repeat length and the position of the material. unrolled.

The task of the present invention is therefore to propose a method and a device for printing a print carrier web inside a rotary printing machine, with which the disadvantages described above can be avoided.

In accordance with the invention this task is solved by means of all the features of claim 1.

Possible designs of the invention are indicated in the dependent claims.

According to the present invention it is provided that with at least one printing roller a printing motif is applied to the printing medium, wherein the printing roller rotates with a peripheral speed, wherein by means of at least one measuring device arranged on the Inside the rotary printing machine a printing length is measured and wherein the peripheral speed of the at least one printing roller is changed if the measured printing length varies from a theoretical printing length.

The fundamental idea of the invention is therefore to measure the print length on the print medium and furthermore conveniently change the peripheral speed of the print roller if this measured print length varies from a theoretical print length. By changing the peripheral speed of the printing roller, the printing length can now be changed, wherein in this case the peripheral speed of the printing cylinder is not changed or at least not in the same proportion. Therefore different peripheral speeds of the printing roller and the printing cylinder can arise. In this case, the relationship is valid that longer formats are printed with a format cylinder drive speed lower than the web speed and shorter formats are printed with a format cylinder drive speed greater than the web speed. . An integral part of the invention is that from now on no changed web tension is applied to the print carrier web, as was the case in the state of the art. This is achieved for example by moving the print carrier web from now on with a constant pulling force. In other words, the web tensions of the print carrier web are not affected. The method according to the invention now makes it possible to fully adjust the printing length in the case of stretch-proof materials such as paper or metal foil.

In accordance with the invention, it is further provided that the measurement of the print length is carried out before the print carrier web reaches the print roller. In this case, the peripheral speed of the printing roller can be individually adjusted in the case of existing printing patterns on the back, even for each of these printing patterns. Depending on the distance of the measuring device from the printing roller along the web path of the print carrier strip, the appropriate time at which the peripheral speed of the printing roller should be changed can be changed for this. print to conveniently change print lengths.

A measured print length and the print length of the print roller changed accordingly form a theoretical print length, with which the print lengths of the following print patterns are compared.

In a further development of the invention, the printing of a printing support strip is provided inside a multi-color rotary printing machine. In this case, the problem arises that the individual printing rollers are shifted in their peripheral speeds in such a way that the individual multi-color printing patterns are printed based on the registration to avoid waste. A preferred solution to this problem is disclosed in the international publication WO 2014/020083 A2.

In accordance with the invention this task is also solved by means of a printing machine according to claim 5, in which the same advantages are indicated, as these were described in relation to claim 1.

Other advantages, characteristics and details of the invention emerge from the following description, in which different embodiments are explained in detail with reference to the figures. In this case, the characteristics mentioned in the claims and in the description may be fundamental to the invention, respectively, each individually by itself or any combination of the mentioned characteristics. Within the scope of the entire disclosure, the characteristics and details that are described in relation to the method according to the invention are obviously valid also in relation to the device according to the invention and respectively vice versa, so that in relation to the disclosure is or may always be mutually referenced to individual aspects of the invention. The individual figures show:

Fig. 1 side view of a printing machine according to the invention, with which the method according to the invention can be carried out.

Fig. 2 side view of a printing machine according to a design of the invention, which is no longer covered by the claims.

The single figure shows a side view of a printing machine according to the invention. This printing machine 1 includes a printing mechanism 2, which has a central printing cylinder 3. The impression cylinder 3 is rotatably housed in a machine frame not shown. Also not shown are consoles, which represent the supports for the inking units 4. Of the inking units 4, only the printing rollers 5 and the ink applicator rollers are shown, for example rollers. cross-linked 6.

The print carrier web 7 is provided to the printing machine on a reel 8, which is rotatably clamped at an unwinding station 9. The unwound print carrier web 7 is guided through several guide rollers 10 from the unwinding station 9 to the pressure roller 11, with which the print carrier strip 7 can be placed on the print cylinder. The web path between the unwinding station 9 and the pressure roller is considered as the supply path 12 of the print carrier web 7.

After the printing support web 7 has passed through the printing mechanism 2, it is supplied to the drying box 15. There it is passed through numerous guide rollers 18 by dryers and / or other non-industrial installations. represented, which serve to harden the printing ink. After exiting the drying box the web 7 is supplied to the winding station 16, where it is further processed into a coil 17. The web 7 is guided between the printing mechanism 2 and the winding station 16 always in such a way that it is positioned with the non-printed side on the guide rollers 18.

In the case of a print carrier band 7 with the back side already printed it is now measured with a sensor, for example a registration sensor. In this case, the print length is determined - preferably with each print motif. This measured value is transmitted to the calculation and control unit 22 via the data cable 21. The calculation and control unit 22 now compares the measured print length with a theoretical print length, which preferably corresponds to the length previously measured print size. If the measured print length varies from the theoretical print length, then the calculation and control unit sends control commands via the control cable 23 to the drive M of the print roller 5. This situation is represented by way of example only for the first inking unit 4, although this is also valid for the other inking units 4. The control command or the control commands lead to a change in the peripheral speed of the printing roller 5, which depends on the magnitude of the variation described above. The print length arising from the new set peripheral speed is now stored as the new theoretical print length in the calculating and control unit 22. Another change of the peripheral speed of the print roller 5 can now be omitted if the print length measurement corresponds to this theoretical value. The adjustment of the other printing rollers 5, which follow in the transport direction T of the printing support strip 7 of the first printing roller, is advantageously carried out according to the method disclosed in the international publication WO 2014/020083 A2.

Figure 2 now shows another embodiment of the invention, which is no longer covered by the claims. Compared to the embodiment of FIG. 1, however, the sensor 20 is now arranged in the transport direction of the print medium band 7 behind the inking units 4. This means that the print medium band 7 already it is printed. However, it is not necessary for the sensor to also be arranged behind the drying box 15. In fact, this can also be provided in front of the drying box 15. The sensor 20 now controls in the case of the print carrier strip 7 printed on the printing machine 1 the printing length and compares it with a value for the theoretical printing length, which can be set for the calculation and control unit. This theoretical printing length can be directly the extension of the printing roller 5. However, if now during the measurement a printing length that varies from this theoretical printing length is determined, then the calculation and control system sends a control command to the motor M of the printing roller 5 to change the peripheral speed. However, in this exemplary embodiment, the theoretical print length is preferably not changed. In this way it is possible to always maintain the same print length inside the print carrier web 7, also in the event of variations in web tension.

Reference symbols list

1 printer machine

2 printing mechanism

3 impression cylinder

4 inking mechanism

5 printing roller

6 cross-linked roller

7 print support band

8 coil

9 unwinding station

10 guide roller

11 pressure roller

12 supply path

13

14

15 drying box

16 winding station

17 coil

18 guide roller

19

20 sensor; measurement facility

21 data cable

22 calculation and control facility

23 control cable

M motor

T conveyor direction of band 7

Claims (5)

1. Procedure to print a printing support band (7) inside a rotary printing machine (1), where - with at least one printing roller (5) a printing motif is applied to the printing support strip (7), wherein the printing roller (5) rotates with a peripheral speed, - by means of at least one measuring installation (20) housed inside the rotary printing machine (1) a printing length is measured, and wherein the measurement of the print length is carried out before the print support strip (7) reaches the print roller (5), where with the measurement facility (20) the print length of a print motif that is already at the rear of the print support strip (7) characterized in that the peripheral speed of the at least one print roller (5) is changed if the measured print length varies by a length of theoretical printing, where the web tensions of the printing support web (7) are not affected. Method according to the preceding claim, characterized in that the peripheral speed of the printing roller (5) is adjusted in such a way that it is printed with the measured printing length. 3. Method according to one of the preceding claims characterized by what The measured print length, to which the peripheral speed of the print roller (5) is set, is stored as the theoretical print length. 4. Method according to one of the preceding claims characterized by what Depending on the distance of the measuring device (20) with respect to the printing roller (5) along the web path of the printing medium strip (7), the appropriate moment is determined, in which it is changed the peripheral speed of the printing roller (5). 5. Printing machine (1) for printing a printing support web (7), wherein the printing machine (1) is provided and installed to carry out the method according to one of claims 1 to 4.