CN111439023B

CN111439023B - Apparatus and method for printing width compensation

Info

Publication number: CN111439023B
Application number: CN202010046648.8A
Authority: CN
Inventors: R.维德曼; P.黑林格
Original assignee: Roland Gauss Network System Co ltd
Current assignee: Roland Gauss Network System Co ltd
Priority date: 2019-01-16
Filing date: 2020-01-16
Publication date: 2024-03-05
Anticipated expiration: 2040-01-16
Also published as: DE102019101024A1; EP3683060A3; ES2893798T3; EP3683060A2; EP3683060B1; CN111439023A

Abstract

A rotary printing press (1) and a method for printing width compensation. The invention is based on the object of proposing a solution by means of which, seen in the web travel direction LR, the width variation of the first printed image applied by means of the first printing unit (4-1) can be compensated. The device according to the invention comprises a rotary printing press (1), in which case at least one image control device (6) is arranged upstream of a cylinder group (5) of the first printing unit (4-1) seen in the web travel direction LR. The method according to the invention relates to a method for operating a rotary printing press (1), in which case the reduction of the web width B seen in the web travel direction LR to the effective width B is performed upstream of the cylinder group (5) of the first printing unit (4-1) seen in the web travel direction LR.

Description

Apparatus and method for printing width compensation

Technical Field

The invention relates to a rotary printing press (rotary printing press) for printing a web of printing material (printing material web) which is guided through the rotary printing press in a web travel direction, wherein the rotary printing press comprises a feeding device for printing the web of material; at least one printing unit comprising a cylinder group (cylinder group) operatively connected with the web of printing material during printing for printing of at least one side of the web of printing material; and at least one image control device.

The invention also relates to a method for operating a rotary press, wherein a printing material web having a web width B is fed to at least one printing unit by means of a feed device in the web travel direction, and wherein, for at least one-sided printing of the printing material web, the material web is operatively connected to a cylinder group of the at least one printing unit, and wherein the web width B of the printing material web is reduced to an effective width B by means of at least one image control device.

Background

Different problems associated with width variations, especially in the case of web-like printing materials inside a printing press, are known from the prior art.

In the case of rotary presses, in particular in the case of web-fed offset presses, in the case of printing of a paper web, for multicolor printing, four printing units are usually arranged one behind the other, seen in the web travel direction, so that the primary colors can be applied to the web of printing material by means of each printing unit. In particular due to the effect of the wetting agent in the case of offset printing, the paper is fanned out in particular perpendicular to the fibre direction, so that the width of the printed material increases with an increasing number of printing units passing through. Since the print image applied by means of the first printing unit increases in width with an increase in the print material, it is common that, as a result of this so-called fan-out effect (fan-out effect), which is also strongly dependent on the respective print material, a so-called image controller is attached downstream of the first printing mechanism as seen in the web travel direction, by means of which image controller the print material web is corrugated upstream of the subsequent printing mechanism and thus narrows in projection towards the print cylinder gap in order to compensate for the widening of the previously applied print image and ensure consistent printing of the primary colors.

Document DE 10 2004 004 264 C5, for example, discloses a printing press of this type equipped with an image controller and a method for compensating an increase in the width of a printing material web.

When printing relatively elastic substrates, for example as in printing web-like plastic films, problems with completely different width variations of the printed material ensue. In the case of a packaging printing machine, the web-like plastic film is unwound from a roll by means of a feeding device, such as a roll changer or unwinder, for example, and fed with or without separate devices for accumulation of web tension of at least one printing mechanism, in which case the printing material is sandwiched between a pair of printing cylinders and printed during rotation of the printing cylinders. For example in the case of offset printing, in the case of flexographic printing, or in the case of the intaglio printing process, a printing unit of this type is used which comprises a printing cylinder in mechanical contact with the printing material.

The printing material is usually printed by means of a plurality of printing units arranged one behind the other, so that the printing material web is clamped and transported for printing by means of a plurality of cylinder groups.

In the case of an elastic substrate (e.g. such as a plastic film), this firm clamping of the printing material web inside the printing units has the result that, however, the printing material, seen in the web travel direction, of the first printing unit in the longitudinal direction downstream of the cylinder group and thus seen in the web travel direction, extends or stretches, so that as a result the width of the printing material is reduced. Due to the fact that such a printing material does not absorb any moisture either, no fan-out of the printing material then takes place. The printed image applied by means of the first printing unit is thus still applied to the printed material with the original web width B, while the printed image applied by means of the subsequent printing unit is applied to the printed material web with a reduced width. As a result of this, the printed image applied by means of the first printing unit is narrower than the printed image applied by means of the subsequent printing unit, resulting in problems of color register (sometimes also referred to as color register) or register, or of individual printed colors or primary colors with each other, respectively.

From practice, a known solution to this problem is known to scale the width of the first printed image accordingly in the preprinting machine, wherein in this case no correction options exist anymore inside the machine, so that it is not possible to react to different behaviors of different printed materials, cylinder coatings, etc. As a result, color registration or deviations in registration, in particular of the printing color or printing color respectively, applied first, may thus occur.

Disclosure of Invention

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

This object is solved by means of a device according to claim 1 and a method according to claim 5. The device according to the invention comprises a rotary printing press, in which case at least one image control device is arranged upstream of the cylinder group seen in the web travel direction LR of the first printing unit seen in the web travel direction LR.

The method according to the invention relates to a method for operating a rotary printing press, in which case the reduction of the web width B, seen in the web travel direction, to the effective width B is performed upstream of the cylinder group of the first printing unit, seen in the web travel direction.

This type of device and this type of method have the advantage that the corresponding specific expansion and the resulting shrinkage of the printed material and the resulting reduction in width of the printed material web can be reacted directly on the printing press without having to scale the first printing form so that a separate color registration or register printing of the individual primary colors with respect to each other is ensured.

In an advantageous embodiment, the image control device is arranged not only upstream of the first printing unit, seen in the web travel direction, but also upstream of the cylinder group of at least one printing unit downstream of the first printing unit, seen in the web travel direction, and also downstream of the printing units, seen in the web travel direction, in addition to the image control device. Thus, it is possible to react to changing web tension ratios inside the printing unit group, for example due to different printing methods, and to adapt the effective web width B inside the printing unit group.

Drawings

Preferred further developments of the invention emerge from the dependent claims and the following description. Various exemplary embodiments of the invention will be described in more detail, but not limited thereto, by means of the accompanying drawings, in which:

fig. 1 shows the variation of the web width B at the first printing unit seen in the web travel direction at a rotary printing press known in the prior art.

Fig. 2 shows a schematic view of a rotary printing press according to the invention.

Fig. 3 shows a schematic top view on a web of printing material upstream and downstream of a first printing unit seen in the web travel direction in a rotary printing press according to the invention.

Fig. 4 shows a schematic view of an advantageous embodiment of a rotary printing press according to the invention.

Fig. 5 shows an alternative to the first embodiment of corrugation for printing a web of material.

Fig. 6 shows an alternative to the second embodiment of corrugation for printing a web of material.

REFERENCE SIGNS LIST

1. Rotary press

2. Printing material web

3. Feeding device

4. Printing unit

5. Roller set

6. Image control device

7. Image controller/image controller nozzle

LR web travel direction

B web width

b effective width.

Detailed Description

Fig. 1 shows a top view onto a printing material web 2 in the region of a rotary printing press 1 known from the prior art, in which case the printing material web 2 is operatively connected to a cylinder group 5 and is printed with a process color or primary color (sometimes also referred to as overprint) on at least one side by at least one of the printing cylinders of the cylinder group 5.

Such a printing press is known, for example, from offset, gravure or flexo printing presses known from the prior art. In the case of offset printing presses, the cylinder group 5 is composed either of a plate cylinder (platen cylinder) for accommodating the printing plate, a transfer cylinder (transfer cylinder) covered with a jacket (blanket) and an impression cylinder (impression cylinder), or of respective pairs of plate cylinders and transfer cylinders on the upper and lower web sides in each case. The printing material web 2 is thus clamped by the cylinder groups 5 of the plurality of printing units, which are usually arranged one behind the other in the web travel direction LR and are conveyed by means of the rotation of the printing cylinders, whereby the corresponding web tension builds up. At least one member for transporting the web is usually also arranged downstream of the at least one printing unit 4, so that in this case the following effect can also be determined.

As a result of the clamping of the printing material web 2 occurring by means of the cylinder groups 5 of the at least one printing unit 4, it is no longer possible to compensate for different web tensions over the entire length of the printing material web 2 located in the printer 1, so that the expansion or stretching of the printing material web 2 occurs in the longitudinal direction and, as a result of the generally higher web tension starting at the first printing unit 4, thus takes place in the web travel direction LR, in particular in the case of printing materials comprising a relatively low modulus of elasticity, for example, as in the case of plastic films, so that the printing material web contracts as a result of the volume of the printing material web 2 remaining constant, so that the original web width B is reduced to the effective width B.

Fig. 1 shows this effect, which is known from the state of the art in the case of rotary presses known from the prior art, in the form of a view perpendicular to the plane spanned by the printed material web 2 in the regions upstream and downstream of the first printing unit 4-1 (seen in the web travel direction LR).

Thereby, the printing material web 2 is fed to and through the first printing unit 4-1 in the web travel direction LR, wherein the printing material web 2 is operatively connected with a cylinder group 5 of the first printing unit 4-1, which is not shown in fig. 1, and which is thus printed in a first printing color or primary color. The printed material web 2 is thus printed on at least one side, seen in the web travel direction LR, which is schematically shown in fig. 1 by means of text fields and graphics.

The printing material web 2 is fed to the first printing unit 4-1 with an original web width B, and the printing material web 2 is contracted due to the nip point in the first printing unit 4-1 and due to the typically higher web tension starting at the first printing unit 4-1, such that downstream of the first printing unit 4-1 the printing material web 2 has an effective width B, which is reduced compared to the original web width B. The reduction in web width B is typically in the range of a fraction of a percent to a small percentage based on web width B, but is sufficient to have a negative visual impact on the printed image.

If the web of printing material 2 is fed to a downstream printing unit 4-2 (which is not shown in fig. 1), wherein the web of printing material 2 has an effective width B which is reduced compared to the original web width B, a deviation in color registration or registration, respectively, occurs when the plates of the first printing unit 4-1 and the second printing unit 4-2 have the same width.

Fig. 2 shows a rotary printing press 1 according to the invention, by means of which rotary printing press 1 the phenomenon shown in fig. 1 is eliminated.

The rotary printing press 1 shown by way of example in fig. 2 is basically a rotary printing press 1, since it is basically known from the prior art, and since it is used for printing a printing material web 2 which is guided through the rotary printing press 1 in a web travel direction LR.

The web of printing material 2 is fed to a printing unit 4 by means of a feeding device 3. A roll changer or unwinder is usually used as the feeding means 3, in which case the web of printed material 2 is unwound from a roll. In most cases, although not mandatory, the feeding device 3 also comprises elements for laterally registering the printed material web 2 and/or for establishing a defined web tension, such as for example a feeding unit.

The web of printing material 2 is fed in a web travel direction LR to a plurality of printing units 4, which printing units 4 are arranged one behind the other as seen in the web travel direction LR. In the case of the example shown in fig. 2, four printing units 4 are arranged one behind the other, the number of printing units 4 can also be correspondingly greater or smaller. Each printing unit 4 comprises a cylinder group 5, which cylinder group 5 consists of a plate cylinder (form cylinder) and a transfer cylinder on the upper web side and an impression cylinder on the lower web side in the example shown in fig. 2. The design of the cylinder group 5 can also be designed so as to differ from the example shown in fig. 2, for example for double sided offset printing, for intaglio printing, or for example for examples comprising a central cylinder arranged around it in a satellite-like manner, as well as a plate cylinder and a transfer cylinder, as is known from flexographic printing.

The web of printing material 2 is clamped by each cylinder group 5, since a corresponding compression has to be performed to transfer the printing colour or primary colour onto the printing material.

Even though a web-fed offset printing press comprising horizontal web guides is shown in an exemplary manner in fig. 2, the invention can also be used in any other configuration of a rotary printing press 1, for example a rotary printing press 1 comprising vertical web guides, in which case the printing units 4 are arranged on top of each other.

The rotary press 1 according to the invention shown in fig. 2 also comprises an image control device 6, which image control device 6 comprises a plurality of image controllers 7 which are arranged adjacent to one another and are generally distributed over the web width B.

These image controllers 7 can be designed as mechanical image controllers 7 in the form of rotatably supported rollers which can be brought into contact with the printing material web 2 in such a form that the printing material web 2 is corrugated.

However, the image controllers 7 may alternatively also be designed as nozzles to which compressed air is applied, and thus as image controller nozzles 7, such that there is no longer a direct mechanical contact between the printing material web 2 and each image controller 7, since an air cushion is established between each image controller 7 and the printing material web 2.

In the case of the rotary printing press 1 according to the invention shown in fig. 2, the image control device 6 is arranged upstream of the cylinder group 5 of the first printing unit 4-1, seen in the web travel direction LR (seen in the web travel direction LR), so that the printing material web 2 has been corrugated upstream of that first cylinder group 5 and thus upstream of that first cylinder group 5 by means of the image control device 6 and its effective width b is thus narrowed. Even if not shown in fig. 2, it is possible to arrange a plurality of image control devices 6 upstream of the cylinder groups 5 of the first printing unit 4-1 in the web travel direction LR or perpendicular to the web travel direction LR for waving of the printing material web 2.

In the case of the illustration shown by way of example in fig. 2, the image control device 6 is arranged upstream of the first printing unit 4-1 as seen in the web travel direction LR. Even though not shown in fig. 2, it is thus possible to arrange the image control device 6 just upstream of the cylinder group 5 of the first printing unit 4-1 and thus already spatially within the contour of the first printing unit 4-1.

Fig. 3 shows a top view onto the printing material web 2 in the area around the first printing unit 4-1 and shows the effect of the process performed by means of the rotary printing press 1 according to the invention.

The basic arrangement of the sections of the printing material web 2 shown in fig. 3 in the upstream or downstream region of the first printing unit 4-1 is identical to the sections shown in fig. 1 (although as a result of the method according to the invention), so that the repetition of the regions of the rotary printing press 1 shown there is dispensed with here.

However, fig. 3 shows an image control device 6, which image control device 6 is covered in this view by the printing material web 2 and which is therefore shown by a dashed line, comprises corresponding five image controllers 7 shown by way of example, and is arranged upstream (seen in the web travel direction LR) of the cylinder group 5 of the first printing unit 4-1, which is not shown in fig. 3.

As already mentioned in fig. 2, whether the image control device 6 is arranged upstream of the first printing unit 4-1 or within the contour of the first printing unit 4-1 but upstream of the cylinder group 5 of the first printing unit 4-1 (seen in the web travel direction LR) is not different, since this is basically a function of the contour of the printing unit 4 and the geometrical arrangement of the cylinder group 5 inside the printing unit 4. The criterion is that the image control device 6 is arranged upstream of the cylinder group 5 of the first printing unit 4-1 and thus in the area of the printing material web 2 that has not yet been printed.

As schematically shown in fig. 3, the web of printing material 2 fed by the feeding device 3 with web width B is corrugated by means of an image control device 6 upstream of the cylinder group 5 of the first printing unit 4-1. The effective width B of the planar projection spanned by the web of printed material 2 is thus smaller than the original web width B, so that the web of printed material 2 which has not yet been printed narrows in top view and thus in the projection plane. The deflection and thus waving of the printing material web 2 can be set by means of the engagement of the image controller 7 of the image control device 6 in such a way that the effective width b upstream of the cylinder group 5 of the first printing unit 4-1 is preferably identical to the effective width b downstream of the first printing unit 4-1, so that the printed images are all applied to the printing material web 2 with equal effective width b by means of a plurality of printing units 4 arranged one behind the other, and thus respectively without color registration or register deviations from the respective primary colors of each other.

Since the narrowing of the printed material web 2 is typically in the range of a fraction of a percent of the web width B, at most in the lower percentage of the web width B, no fold formation occurs as the printed material web 2 passes through the cylinder group 5, similar to the known prior art.

Fig. 4 shows an advantageous design of the rotary press 1, in which case, in addition to the first printing unit 4-1, at least one image control device 6 is also arranged upstream of the cylinder group 5 of the at least one printing unit 4, seen in the web travel direction LR, which is arranged downstream of the first printing unit 4-1, seen in the web travel direction LR.

In the case of the example shown in fig. 4, the image control device 6 is arranged upstream of the cylinder group 5 of the first printing unit 4-1, and the image control device 6 is additionally arranged upstream of the cylinder group 5 of the third printing unit 4-3. This is purely an exemplary embodiment, since the image control device 6 upstream of the cylinder group 5 of the first printing unit 4-1 may additionally be arranged upstream of the cylinder group 5 of the second printing unit 4-2 and/or upstream of the cylinder group 5 of the third printing unit 4-3 and/or upstream of the cylinder group 5 of the fourth printing unit 4-4 and optionally downstream of other printing units 4 not shown.

By means of such a design of the rotary press 1 or by means of a method which is carried out accordingly therewith, it is also possible to change and set the effective width b within the group of printing units 4, for example when different printing settings and/or different printing methods are used.

Fig. 5 shows a schematic view of the image control device 6 in the design in the web travel direction LR, in which case the image control device 6 is arranged on the underside of the printing material web 2 and the printing material web 2 is thus corrugated in the form of circular segments. With this design, the web of printed material 2 is deflected in one direction based on the plane spanned by the web of printed material 2 in order to reduce the original web width B to the effective width B.

In the case of the alternative shown in fig. 5, the image control device 6 has, for example, five image controllers 7, wherein the number of image controllers 7 is generally not important and can in practice vary between two and ten, which is essentially a function of the web width B and the printed material.

Fig. 6 shows a schematic illustration in the web travel direction LR corresponding to fig. 5 in a further embodiment, in which case the printing material web 2 is corrugated on the upper and lower sides of the printing material web 2 by means of a respective image control device 6. With this design, the web of printed material 2 is deflected in both directions based on the plane spanned by the web of printed material 2 in order to reduce the original web width B to the effective width B.

In the case of the alternative shown in fig. 6, the upper image control means 6 has, for example, two image controllers 7 and the lower image control means 6 has three image controllers 7, whereby the number of image controllers 7 is generally not large and can in practice vary between two and ten, which is basically a function of the web width B and the printed material.

Claims

1. A rotary printing press (1) for printing a web of printing material (2), which web of printing material is guided through the rotary printing press (1) in a web travel direction LR, wherein the rotary printing press (1) comprises a feed device (3) for the web of printing material (2), at least one printing unit (4) comprising a cylinder group (5) operatively connected with the web of printing material (2) during the printing for printing on at least one side of the web of printing material (2), and at least one image control device (6), wherein the at least one image control device (6) is arranged upstream of the cylinder group (5) of a first printing unit (4-1) seen in the web travel direction LR, characterized in that the effective width b of the web of printing material is narrowing upstream of the first printing unit seen in the web travel direction LR.

2. Rotary printing press according to claim 1, characterized in that, in addition to the first printing unit (4-1), the at least one image control device (6) is arranged upstream of a cylinder group (5) of at least one printing unit (4) as seen in the web travel direction LR, the at least one printing unit (4) being arranged downstream of the first printing unit (4-1) as seen in the web travel direction LR.

3. Rotary printing press according to any one of claims 1 to 2, characterized in that the image control device (6) comprises at least one mechanical image controller, which is operatively connected to the printing material web (2).

4. Rotary printing press according to any one of claims 1 to 2, characterized in that the image control device (6) comprises at least one image controller nozzle.

5. Method for operating a rotary printing press (1), wherein a web of printing material (2) having a web width B is fed to at least one printing unit (4) in a web travel direction LR by means of a feeding device (3), and wherein for at least one side printing of the web of printing material (2), the web of printing material (2) is operatively connected to a cylinder group (5) of the at least one printing unit (4), and wherein the web width B of the web of printing material (2) narrows to an effective width B due to web tension which increases downstream of the cylinder group (5) of the first printing unit (4-1) seen in the web travel direction LR, characterized in that, in order to compensate for web tension-related narrowing of the web of printing material (2), the web of printing material is narrowed to an effective web having the effective width B seen in the web travel direction LR by means of an image controller upstream of the first printing unit (4-1).

6. A method according to claim 5, characterized in that reducing the web width B to an effective width B seen in the web travel direction LR is performed upstream of the cylinder group (5) of the first printing unit (4-1) seen in the web travel direction LR and upstream of the cylinder group (5) of a printing unit (4) arranged downstream of the first printing unit (4-1) seen at least in the web travel direction LR.

7. A method according to any one of claims 5-6, characterized in that the web of printed material (2) is deflected in only one direction based on a plane spanned by the web of printed material (2) to reduce the web width B to an effective width B.

8. A method according to any one of claims 5-6, characterized in that the web of printed material (2) is deflected in two directions based on a plane spanned by the web of printed material (2) in order to reduce the web width B to an effective width B.