EP3683060B1 - Device and method for print width adjustment - Google Patents

Description

The invention relates to a web-fed printing machine for printing a web of printing material guided through the web-fed printing machine in one direction of travel, the web-fed printing machine having a feed device for the web of printing material, at least one printing unit with a cylinder group that is in operative connection with the web of printing material during printing for at least one-sided printing of the web of printing material, and at least one Includes image control device.

The invention also relates to a method for operating a web-fed printing machine, wherein a printing material web with a web width B is fed to at least one printing unit in a web running direction by means of a feed device, and wherein for at least one-sided printing of the printing material web, it is brought into operative connection with a cylinder group of the at least one printing unit , and wherein the web width B of the printing substrate web is reduced to an effective width b by means of at least one image control device.

From the prior art, various problems with changing the width, in particular in the case of web-like printing materials within the printing press, are known.

In web printing machines, especially web offset printing machines in which paper webs are printed, four printing units are usually arranged one behind the other for multicolored printing in the direction of web travel, so that a process color can be applied to the printing substrate web with each printing unit. In particular, due to the action of the dampening solution in offset printing, the paper grows in particular transversely to the fiber direction, so that the width of the printing substrate increases as the number of printing units passed through it increases. Since that applied with the first printing units Due to this so-called fan-out effect, which also depends heavily on the respective printing material, it is common to attach so-called image regulators after the first printing unit as seen in the direction of web travel, with which the printing material web remains in front of the subsequent printing units and thus narrowed in the projection onto the printing cylinder gap in order to compensate for the broadening of the previously applied print images and to ensure that the process inks are printed congruently.

the DE 10 2004 004 264 C5 discloses, for example, such a printing press equipped with image regulators and a method for compensating for the increase in width of the printing substrate web.

the DE 199 18 399 A1 teaches a web-fed printing machine in which a web width that changes due to tensile stresses between the printing units is compensated for by using an additional traction device in front of the first printing unit, in that a corresponding web tension is built up in the area in front of the first printing unit.

the DE 10 2015 112 780 A1 discloses a web printing machine in which the web width, which increases due to moisture absorption, is compensated by means of image regulators arranged after the first printing unit, the fan-out compensation process being carried out in an automated manner by detecting printed marks.

A completely different problem with the change in the width of the printing material arises when printing relatively elastic substrates such as, for example, printing sheet-like plastic films. In packaging printing machines, the web-shaped plastic film is unrolled from rolls by means of a feed device such as a roll changer or unwinder and, with or without separate means for building up a web tension, is fed to at least one printing unit in which the printing material is clamped between a pair of printing cylinders and printed while the printing cylinder is rotating will. Such Printing units with printing cylinders that are mechanically in contact with the printing material are used, for example, in offset printing, flexographic printing or gravure printing.

The printing material is usually printed with several printing units arranged one behind the other, so that the printing material web is clamped and conveyed by several cylinder groups for printing.

With elastic substrates such as plastic films, this firm clamping of the printing material web within the printing units, however, results in the printing material being stretched or stretched after the cylinder group, viewed in the direction of web travel, in the longitudinal direction and thus viewed in the direction of travel of the web, so that as a result the The width of the substrate is reduced. Since printing materials of this type do not absorb moisture either, the printing material does not grow out in return. The print image, which is applied with the first printing unit, is thus still applied to the printing material in the original web width B, while the printing images, which are applied with the subsequent printing units, are applied to a printing material web with a reduced width. The result of this is that the printed image applied by the first printing unit is narrower than the printed image applied by the subsequent printing units, which results in problems with the register of the individual printing or process colors with respect to one another.

As a solution to this problem, it is known from practice that the width of the first print image is scaled accordingly in the preliminary stage, in which case there are no more correction options within the machine, so that it does not react to different behavior of different printing materials, cylinder lifts, etc. can be. As a result, deviations in the register or in the register, in particular of the printing or process color applied first, can occur.

The invention is therefore based on the object of creating a solution with which the change in the width of the first printed image can be compensated.

The object is achieved by a device according to claim 1 and a method according to claim 3. The device according to the invention comprises a web printing machine in which the at least one image control device, which includes at least one mechanical image regulator, which can be brought into operative connection with the printing substrate web and / or comprises at least one image regulator nozzle, viewed in the web direction LR, in front of the cylinder group of the first printing unit, seen in the web direction LR is arranged.

The method according to the invention relates to a method for operating a web-fed printing machine, in which the reduction of the web width B to an effective width b is carried out in front of the cylinder group of the first printing unit, seen in the web running direction.

Such a device and such a method has the advantage that it is possible to react directly to the respective printing substrate-specific expansion and the resulting constriction and thus width reduction of the printing substrate web without having to scale the first printing form a register or register printing of the respective process colors to each other is ensured.

In an advantageous embodiment, an image control device is not only arranged in front of the first printing unit as seen in the direction of web travel, but in addition to this image control device, in front of the cylinder group at least one printing unit following the first printing unit in the direction of web travel, an image regulator is also arranged downstream in the direction of web travel. It is thus possible to react to changing web tension conditions within the printing unit assembly, for example resulting from different printing processes, and to adapt the effective web width B within the printing unit assembly.

Fig. 1

die Veränderung der Bahnbreite B an der in Bahnlaufrichtung gesehen ersten Druckeinheit an aus dem Stand der Technik bekannten Rollendruckmaschinen

Fig. 2

eine schematische Darstellung einer erfindungsgemäßen Rollendruckmaschine

Fig. 3

eine schematische Draufsicht auf die Bedruckstoffbahn vor und nach der in Bahnlaufrichtung gesehen ersten Druckeinheit in einer erfindungsgemäßen Rollendruckmaschine

Fig. 4

eine schematische Darstellung einer vorteilhaften Ausgestaltung einer erfindungsgemäßen Rollendruckmaschine

Fig. 5

eine erste Ausführungsvariante zur Verwellung der Bedruckstoffbahn

Fig. 6

eine zweite Ausführungsvariante zur Verwellung der Bedruckstoffbahn

Preferred developments of the invention emerge from the subclaims and the following description. Various exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being restricted thereto. It shows:

Fig. 1

the change in the web width B on the first printing unit, seen in the direction of web travel, on web printing machines known from the prior art

Fig. 2

a schematic representation of a web printing machine according to the invention

Fig. 3

a schematic plan view of the printing material web before and after the first printing unit in a web printing machine according to the invention, as seen in the direction of web travel

Fig. 4

a schematic representation of an advantageous embodiment of a web printing machine according to the invention

Fig. 5

a first embodiment variant for curling the printing substrate web

Fig. 6

a second embodiment variant for curling the printing substrate web

Fig. 1 shows a top view of the printing material web 2 in the area of a web printing machine 1 known from the prior art, in which the printing material web 2 is in operative connection with a cylinder group 5 and is printed on at least one side with a printing or process color via at least one of the printing cylinders of the cylinder group 5 will.

Such printing machines are, for example, offset, gravure or flexographic printing machines known from the prior art. In the case of an offset printing machine, the cylinder group 5 consists either of a plate cylinder for receiving the printing form, a transfer cylinder, which is covered with a printing blanket and an impression cylinder, or a pair of plate and transfer cylinders each on the top and bottom of the web. The printing substrate web 2 is thus clamped by the cylinder groups 5 of the usually plurality of printing units arranged one after the other in the web running direction LR and transported by the rotation of the printing cylinders, whereby a corresponding web tension is built up. Even after the at least one printing unit 4, at least one component for conveying the web is usually also arranged, so that the effect described below can also be determined in such a case.

Due to the clamping of the printing substrate web 2 effected by the cylinder group 5 of the at least one printing unit 4, different web tensions can no longer be compensated over the entire length of the printing substrate web 2 located in the printing press 1, so that, due to the usually higher web tension from the first printing unit 4, in particular In the case of substrates with a relatively low modulus of elasticity, such as plastic films, there is an elongation or stretching of the substrate web 2 in the longitudinal direction and thus in the direction of the direction of travel LR, so that as a result of the constant volume of the substrate web 2 it constricts, so that the original web width B. is reduced to an effective width b.

Fig. 1 shows this effect known from the prior art web printing machines 1 in the form of a view perpendicular to the plane spanned by the printing substrate web 2 in the area before and after the first printing unit 4-1, seen in the web running direction LR.

The printing substrate web 2 is fed to the first printing unit 4-1 in the web running direction LR and runs through it, the printing substrate web 2 in operative connection with the in Fig. 1 cylinder group 5 (not shown) of the first printing unit 4-1 is standing and is thus printed with a first printing or process color. Viewed in the web running direction LR, the printing material web 2 is thus printed on at least one side, which is shown in FIG Fig. 1 is shown schematically by text fields and a graphic.

The printing material web 2 is fed to the first printing unit 4-1 with the original web width B, due to the nip inside the first printing unit 4-1 and the usually higher web tension from the first printing unit 4-1, the printing material web 2 constricts so that after the first printing unit 4-1, the printing substrate web 2 has an effective width b that is reduced compared to the original web width B. The reduction in web width B is usually in the range from a few per mille to low percentage values, based on web width B, but this is sufficient for a visual impairment of the printed image.

If this printing substrate web 2 is provided with a printing substrate web 2 of a subsequent, in Fig. 1 If the printing unit 4-2, not shown, is supplied, there are deviations in the register or register if the printing forms of the first printing unit 4-1 and the second printing unit 4-2 have the same width.

Fig. 2 shows a web printing machine 1 according to the invention, with which the in Fig. 1 phenomenon is eliminated.

In the Fig. 2 The web-fed printing machine 1 shown as an example is essentially a web-fed printing machine 1, as is essentially known from the prior art and is used for printing a printing material web 2 guided through the web-fed printing machine 1 in a web travel direction LR.

The printing material web 2 is fed to the printing units 4 by means of a feed device 3; reel changers or unwinders are usually used as the feeding device 3, in which the printing material web 2 is unwound from a roll. In most cases, although not necessarily, the feed device 3 also comprises elements for laterally aligning the printing material web 2 and / or for building up a defined web tension, such as an infeed unit.

The printing substrate web 2 is fed with the web running direction LR to a plurality of printing units 4 arranged one behind the other as seen in the web running direction LR. The in Fig. 2 In the example shown, four printing units 4 are arranged one behind the other, the number of printing units 4 can also be correspondingly larger or smaller. Each printing unit 4 comprises a cylinder group 5, which in the in Fig. 2 The example shown consists of a forme cylinder and a transfer cylinder on the upper side of the web and an impression cylinder on the underside of the web. The design of the cylinder group 5 can also deviate from the in Fig. 2 be configured in the example shown, for example for double-sided offset printing, for gravure printing or for example with a central cylinder and therefore satellite-shaped forme and transfer cylinders, as is known from flexographic printing.

The printing material web 2 is clamped by each cylinder group 5, since a corresponding pressure must prevail for the transfer of the printing or process color to the printing material.

Albeit in Fig. 2 For example, if a web offset printing machine with horizontal web guidance is shown, the present invention can also be applied to any other configuration of a web printing machine 1, for example a web printing machine 1 with vertical web guidance, in which the printing units 4 are arranged one above the other.

In the Fig. 2 The web-fed printing press 1 according to the invention shown further comprises an image regulating device 6 which comprises a plurality of image regulators 7 which are arranged next to one another and are generally distributed over the web width B.

These image regulators 7 can either be designed as mechanical image regulators 7 in the form of rotatably mounted rollers, which are brought into contact with the printing substrate web 2 in the form so that the printing substrate web 2 remains.

However, the image regulators 7 can alternatively also be designed as nozzles to which compressed air is applied and thus as image regulator nozzles 7, so that there is no longer any direct mechanical contact between the printing substrate web 2 and each image regulator 7, since there is between each image regulator 7 and the printing substrate web 2 an air cushion builds up.

At the in Fig. 2 The web-fed printing machine 1 according to the invention shown here, the image control device 6 is arranged in front of the cylinder group 5 of the first printing unit 4-1, seen in the web direction LR, as seen in the web direction LR, so that the printing material web 2 is already in front of the very first cylinder group 5 and thus in front of the very first cylinder group 5 by means of an image control device 6 lingers and is thereby narrowed in its effective width b. Albeit in Fig. 2 not shown, it is also possible to arrange a plurality of image regulating devices 6 in front of the cylinder group 5 of the first printing unit 4-1, in the direction of travel LR or perpendicular to it, in order to curl the printing substrate web 2.

At the in Fig. 2 In the illustration shown, the image control device 6 is arranged in front of the first printing unit 4-1, viewed in the direction of web travel LR. Albeit in Fig. 2 not shown, it is also possible to arrange the image regulating device 6 relatively just in front of the cylinder group 5 of the first printing unit 4-1 and thus, in spatial terms, already within the contour of the first printing unit 4-1.

Fig. 3 represents a top view of the printing substrate web 2 in the area around the first printing unit 4-1 and shows the effect of the method carried out with the web printing machine 1 according to the invention.

The basic structure of the in Fig. 3 The illustrated section of the printing substrate web 2 in the area before and after the first printing unit 4-1 is identical to that in FIG Fig. 1 shown excerpt, albeit with the result of the method according to the invention, so that a repetition of the area of the web-fed printing machine 1 shown there is dispensed with at this point.

However, it shows Fig. 3 the image regulating device 6, which is covered in this view by the printing substrate web 2 and therefore shown in dashed lines, with the corresponding five image regulators 7, shown by way of example, which, viewed in the web running direction LR, are in front of the in FIG Fig. 3 cylinder group 5, not shown, of the first printing unit 4-1, viewed in the direction of web travel LR, is arranged.

As already under Fig. 2 mentioned, it makes no difference whether the image control device 6 is arranged in front of the first printing unit 4-1 or within the contour of the first printing unit 4-1 but in front of the cylinder group 5 of the first printing unit 4-1 as seen in the direction of web travel LR, since this is in the Is essentially dependent on the contour of the printing unit 4 and the geometric arrangement of the cylinder group 5 within the printing unit 4. The decisive criterion is that the image control device 6 is arranged in front of the cylinder group 5 of the first printing unit 4 - 1 and thus in the area of the printing substrate web 2 that is still unprinted.

As in Fig. 3 shown schematically, the printing material web 2 fed by the feed device 3 is curled with the web width B in front of the cylinder group 5 of the first printing unit 4 - 1 by means of an image control device 6. The effective width b projected onto the plane spanned by the printing substrate web 2 is therefore smaller than the original web width B, so that the still unprinted printing substrate web 2 is narrowed in the top view and thus in the projected plane. the The deflection and thus the curling of the printing substrate web 2 can be adjusted by adjusting the image regulator 7 of the image regulating device 6 so that the effective width b in front of the cylinder group 5 of the first printing unit 4-1 is preferably identical to the effective width b after the first printing unit 4- 1, so that the print images, which are all applied to a printing substrate web 2 with an identical effective width b by the usually plurality of printing units 4 arranged one behind the other, and thus do not have any register or register discrepancies between the respective process colors.

Since the narrowing of the printing substrate web 2 is usually in the per thousand range of the web width B, at most in the lower percentage range of the web width B, no wrinkling occurs when the printing substrate web 2 runs through the cylinder group 5, analogous to the already known prior art.

Fig. 4 shows an advantageous embodiment of a web printing machine 1, in which the at least one image control device 6 is arranged in addition to the first printing unit 4-1 seen in the direction of web travel LR also in front of the cylinder group 5 of at least one of the first printing units 4-1, seen in the direction of web travel LR downstream printing unit 4 .

The in Fig. 4 In the example shown, an image regulating device 6 is arranged in front of the cylinder group 5 of the first printing unit 4-1 and, in addition, an image regulating device 6 is arranged in front of the cylinder group 5 of the third printing unit 4-3. This is a purely exemplary embodiment, since an image control device 6 is additionally in front of the cylinder group 5 of the first printing unit 4-1 also in front of the cylinder group 5 of the second printing unit 4-2 and / or in front of the cylinder group 5 of the third printing unit 4-3 and / or in front the cylinder group 5 of the fourth printing unit 4-4 and possibly subsequent, not graphically illustrated further printing units 4 can be arranged.

With such a configuration of the web-fed printing machine 1 or the method carried out with it, it is possible to change and set the effective width b within the network of printing units 4, for example when different print settings and / or different printing processes are used.

Fig. 5 shows a schematic view of the image control device 6 in the web running direction LR in an embodiment in which an image control device 6 is arranged on the underside of the printing substrate web 2 and the printing substrate web 2 is thus corrugated in the form of a circular arc segment. In this embodiment, in order to reduce the original web width B to an effective width b, the printing substrate web 2 is deflected in one direction in relation to the plane spanned by the printing substrate web 2.

At the in Fig. 5 As shown in the variant shown, the image control device 6 has, for example, five image regulators 7, the number of image regulators 7 generally not being decisive and in practice can vary between two and ten, which is essentially dependent on the web width B and the printing material.

Fig. 6 shows a schematic view in the direction of web travel LR comparable to FIG Fig. 5 in another embodiment, in which the printing substrate web 2 is dwelled on the top and bottom of the printing substrate web 2 by a respective image control device 6. In this embodiment, in order to reduce the original web width B to an effective width b, the printing substrate web 2 is deflected in both directions in relation to the plane spanned by the printing substrate web 2.

At the in Fig. 6 As shown in the variant, the upper image control device 6 has two image regulators 7 and the lower image control device 6 has three image regulators 7, the number of image regulators 7 generally not being decisive and can vary in practice between two and ten, which is essentially dependent on the Web width B and the substrate.

List of reference symbols

1

Web press

2

Substrate web

3rd

Feeding device

4th

Pressure unit

5

Cylinder group

6th

Image control device

7th

Image regulator / image regulator nozzle

LR

Direction of web travel

B.

Web width

b

effective width

Claims (6)

1. A web-fed printing press (1) for printing a printing material web (2), which is guided through the web-fed printing press (1) in a web running direction LR, wherein the web-fed printing press (1) comprises a feed means (3) for the printing material web (2), at least one printing unit (4) comprising a cylinder group (5), which is in operative connection with the printing material web (2) during the printing, for the at least one-sided printing of the printing material web (2), and at least one image regulating means (6), wherein the image regulating means comprises at least one mechanical image regulator (7), which can be brought into operative connection with the printing material web (2), and/or at least one image regulator nozzle (7), characterized in that the at least one image regulating means (6) is arranged upstream of the cylinder group (5), viewed in the web running direction LR, of the first printing unit (4-1), viewed in the web running direction LR, wherein the printing material web can be narrowed in its effective width b by means of the upstream of the first printing unit, viewed in the web running direction.
2. The web-fed printing press according to claim 1, characterized in that the at least one image regulating means (6), in addition to the first printing unit (4-1), viewed in the web running direction LR, is also arranged upstream of the cylinder group (5) of at least one printing unit (4), which is arranged downstream from the first printing unit (4-1), viewed in the web running direction LR.
3. A method for operating a web-fed printing press (1), wherein a printing material web (2) with a web width B is fed to at least one printing unit (4) in a web running direction LR by means of a feed means (3), and wherein for the at least one-sided printing of the printing material web (2), the latter is brought into operative connection with a cylinder group (5) of the at least one printing unit (4), and wherein the web width B of the printing material web (2) is narrowed to an effective width b due to the web tension, which is increased downstream from the cylinder group (5) of the first printing unit (4-1), viewed in the web running direction LR, characterized in that to compensate the web tension-related narrowing of the printing material web (2), the latter is narrowed to the effective web by means of image regulators (7) upstream of the first printing unit (4-1), viewed in the web running direction LR.
4. The method according to claim 3, characterized in that the reduction of the web width B to an effective width b is carried out upstream of the cylinder group (5), viewed in the web running direction LR, of the first printing unit (4-1), viewed in the web running direction LR, and upstream of the cylinder group (5), viewed at least in the web running direction, of a printing unit (4) arranged downstream from the first printing unit (4-1), viewed in the web running direction LR.
5. The method according to one of claims 3 to 4, characterized in that the printing material web (2) is deflected only in one direction, based on the plane spanned by the printing material web (2), in order to reduce the web width B to an effective width b.
6. The method according to one of claims 3 to 4, characterized in that the printing material web (2) is deflected in both directions, based on the plane spanned by the printing material web (2), in order to reduce the web width B to an effective width b.

Images