EP2296891B1 - Device for cold foil embossing - Google Patents

Description

The invention relates to a device and a method for transferring imaging layers from a carrier foil to printed sheets according to the preambles of claims 1 and 6.

It is known to produce metallic layers on printed sheets by means of a film transfer process. So is in the EP 0 569 520 B1 a printing material and a printing apparatus using this material are described. In this case, a sheet-processing machine is shown, which has a feeder and a boom, wherein printing units and a coating module are arranged between the two units. In at least one of the printing units, an adhesive pattern is applied by means of the planographic printing process. This adhesive pattern is applied in a cold printing process and has a specific imaging subject. In the printing unit following the coating module with a counter-pressure cylinder and a press roller, a film guide is provided. This is designed in such a way that a film strip or a transfer film is guided through the transfer nip of the coating module between the impression cylinder and the press roll from a film supply roll. The film strip is rewound on the outlet side after leaving the coating module. The transfer film has a carrier layer on which imaging layers such as metallic layers, for example of aluminum, can be applied. Between the metallic layer and the carrier film, a separating layer is provided, which ensures that the metallic layer can be removed from the carrier layer.

When printing sheets are transported through the printing unit, each sheet is given an adhesive pattern. Thereafter, the sheet is passed through the coating module, being brought by means of the press roller on the impression cylinder resting sheet with the film material in combination. At the same time, the metal layer lying down is narrow Connect to the adhesive areas on the sheet. After further transporting the printing sheet, the metallic layer adheres only in the area provided with the adhesive pattern. The carrier film is thus removed from the metallic layer in the region of the adhesive pattern. The used in this way transfer film is wound up again. The print sheet is laid out in the coated state.
It is known to use such coating modules, for example in printing units of printing presses. A disadvantage of the known devices is that they can not be used flexibly.

So is about in WO 2005/100025 A 1 describes a pad for an embossing device. In this case, a device for the cold foil transfer is used in a sheet-processing printing press, which uses the blanket cylinder of a printing unit used as a coating module as a press roller for the guidance of a transfer film web. The film transfer device can also be operated with a timed supply of the transfer film web to a transfer nip in the coating module. For example, drives of film rolls or dancer rolls are described as clock devices.

Out EP 0 987 205 A1 are described a loop buffer for a material web and its use. Here, a stamping foil web is guided from a film roll to a hot foil stamping station and wound up after the stamping process on a further film roll. The film web is guided through a loop memory, which is acted upon by negative pressure. This can form in the loop memory a variable web loop of the film web. The transport of the film web is carried out by means of the film web entangled transport rollers and the film web holding suction devices, which are each provided with their own drive motors.

Out EP 0 858 888 A2 is a flat-stamping machine with flat press, embossing table, tooling plate and a film web known. Film loop stores form a film loop with a suction device on the film web exerted air pressure difference. With a film feed and a tensioning device on each side of the flat press the film web is stopped in the printing phase on the embossing table according to the press cycle by controlling the film feed and pulled in the unpressurized phase in the next embossing position. Speed differences between the embossing feed rate and the web speed at the unwind roll or take-off device are compensated by increasing and decreasing the loops in the film stores.

The object of the invention is therefore to provide a device by means of which the transfer of an imaging layer, e.g. a metallization layer can be done on a sheet safely, economically and accurately, the device should be manageable for an extended range of applications. In particular, a partial film application is to be made possible.

The solution to this problem results in a device according to the features of claim 1 and a method according to claim 6.

The device provides a clock system for guiding the film web. Advantageously, the device is characterized in that a press roller has a pressing surface which occupies a partial area of the total area of a printed sheet.

Advantageously, such press surfaces are designed as tensionable segments or as cut-out rubber blankets or as passably produced, preferably photopolymer high-pressure plates or as detachable, for example under magnetic action, attachable pressing segments.

• eine polymere Schneidplatte z.B. aus der Klischeeherstellung mittels eines Flachbettplotters, ggf. auch mit einem Trägermaterial aus Aluminium oder Polyester, oder
• eine Fotopolymerplatte z.B. aus einer Belichtung ggf. mit Aluminiumblech/- folie als Trägermaterial.
• Verwendbar ist auch ein Gummituch, das auf einem Metallträger aufgebracht ist; ein solches Gummituch kann ggf. eine dämpfende Zwischenschicht aufweisen und mit einer dünnen, aber harten und glatten Deckschicht versehen sein.

Different working materials can be used for this purpose. A so-called stripped rubber blanket can be used with the printing surface removed to the effective area,

• a polymeric cutting plate, for example, from the cliché production by means of a Flachbettplotters, possibly also with a support material made of aluminum or polyester, or
• a photopolymer plate, for example, from an exposure optionally with aluminum sheet / foil as a carrier material.
• Also usable is a blanket which is applied to a metal support; Such a blanket may optionally have a cushioning intermediate layer and be provided with a thin but hard and smooth cover layer.

As a substructure of the corresponding partial press fabric is provided to use a pad with or without damping effect such as a vacuum blanket.
As clamping systems arise a clamping spindle as in a blanket cylinder known or so-called combination clamping rails for blankets or printing plates, as known from the blanket cylinders or the form of cylinders. Depending on the structure, the surface of the press cylinder elevator is also suitable for profiled embossing.

This results in an extended range of applications for the process of cold foil stamping. The makeready shortening is achieved by prepared press cylinder lifts. In addition, register automation can be introduced. As a solution, add the press cylinder to a register system, e.g. is executed via register pins. The press cylinder should be adjustable e.g. in the manner of a register system for automatic printing plate tension. The side and circumferential register can be adjustable as in a forme cylinder. In addition, the press cylinder elevator may be provided with register punches.

The device can also be advantageously used in order to improve the use of the film by dividing the transfer film into one or more partial film webs of lesser width. In combination with the The aforementioned methods can be used side by side so also different types of films.

To ensure the efficiency of the coating process can be provided to control the film feed such that the transfer film is then stopped when no transmission of the imaging or metallization takes place.

Advantageously, a control of the transfer film can be carried out such that, when passing through a cylinder channel receiving the grippers of the sheet-guiding impression cylinder, the film feed is stopped, wherein the press roll then passes in a sliding manner under the transfer film.

To improve the gloss effect, the image-forming layer can be applied by means of so-called UV negative-pressure ink. The UV negative pressure ink is applied by means of the printing unit for the adhesive in a corresponding manner via an offset printing plate.

Advantageously, it is also possible to provide a plurality of coating modules behind one another within a sheet-processing machine. Thus, the application of different imaging coatings or metallization layers within a subject can take place one after the other. In this case, it is possible to transmit the imaging layers next to one another using a single adhesive pattern with all image-pattern elements. It is also possible to provide a first adhesive pattern in a first coating module with a first image-forming coating or metallization layer and, in the following, to apply another, the first enclosing adhesive pattern and to provide it with another image-forming coating or metallization layer.

In the following the invention is illustrated in more detail with reference to figures.

• Figur 1 eine grundsätzliche Darstellung einer Druckmaschine mit einer Folientransfereinrichtung und
• Figuren 2 bis 5 den Aufbau eines erfindungsgemäßen Beschichtungsmoduls mit einer Folientransfereinrichtung und verschiedenen Varianten zur taktweisen Folienführung

Showing:

• FIG. 1 a basic illustration of a printing machine with a film transfer device and
• FIGS. 2 to 5 the structure of a coating module according to the invention with a film transfer device and various variants for intermittent film guide

• Ein Druckbogen wird zunächst mit einem flächigen oder bildgebenden Klebstoffmuster versehen (Druckwerk als Auftragwerk 1).
• Im Folgedruckwerk wird der Druckbogen gemeinsam mit einer Transferfolie 5 unter Pressung durch einen Transferspalt 6 geführt, (Beschichtungswerk 2).

FIG. 1 shows parts of a sheet-fed rotary printing press, which contains two printing units and is used for the following purposes:

• A printed sheet is first provided with a two-dimensional or imaging adhesive pattern (printing unit as commissioned work 1).
• In the following printing unit, the printed sheet is guided together with a transfer film 5 under pressure through a transfer nip 6 (coating unit 2).

The applicator 1 may be a per se known offset printing unit with an inking unit 11, a plate cylinder 12 and a blanket cylinder 13. The blanket cylinder 13 cooperates with a counter-pressure cylinder 4.

The coating unit 2 can also be formed by an offset printing unit. The transfer nip 6 in the coating unit 2 is formed by a press roll 3 and an impression cylinder 4. The press roller 3 may correspond to the blanket cylinder. The press roll 3 may also correspond to the forme cylinder of a paint module. Within the coating unit 2 used for the film transfer, a web guide 14 for transfer films is shown. The transfer film 5 is thereby switched on and executed by protective devices 15 of the coating unit 2.

The film supply roll 8 is assigned to the coating unit 2 on the sheet feed side. The film supply roll 8 has a rotary drive 7 for the continuous controlled feeding of the transfer film to the coating unit 2. In the film feeder deflection or tension rollers for guiding the Transfer film 5 may be provided in a substantially constant tension against the press roller 3. On the downstream side of the printing unit, a film collecting roller 9 is provided for the used sheet material. A rotary drive 7 on the film collecting roller 9 is always advantageous. It can even be provided that the transfer film 5 is conveyed on the outlet side by means of the rotary drive 7 and held taut on the inlet side by means of a brake.

The press roll 3 (as a blanket cylinder or forme cylinder or separate press roll) carries on its surface a compressible or damping, e.g. also provided with a compressible intermediate layer element. For this purpose, the press roll 3 can be provided with a press fabric 10, for example as a plastic cover, comparable to a blanket or blanket, which is held in a cylinder channel on clamping devices.

To ensure the efficiency of the coating process can be provided, the film feed of the transfer film 5 from the film supply roll 8 to the transfer nip 6 and the film collection roller 9 is gradually controlled, the transfer film 5 is then stopped, if no transfer of imaging or covering layers should take place.
The associated device preferably includes a corresponding feed control for the transfer sheet 5, which ensures that at least the lying in the region of the press roller 3 and the impression cylinder 4 part of the film web is stationary as long as the cylinder channel passes.
This will be later in FIGS. 2 to 5 Details explained.

A further improvement of the film utilization of the type described results when the transfer film 5 is divided into one or more Teilfolienbahnen lesser width. Thus, with appropriate control by means of the device or devices for timing the film feed each of the sub-film webs, the utilization of the transfer film 5 can be improved even in zonally different lengths coating areas within an arc. Furthermore, dryer 16 can be provided in the film application module thus formed from the applicator 1 and the coating unit 2, by means of which the adhesive application or the entire film coating can be dried. Here, for example, UV dryers come into question.

Furthermore, the film application module may include a monitoring device 17 for scanning the sheet surface. The monitoring device 17 enables the evaluation of image contents of the coating and the detection of defects in the film coating. Such a monitoring device can also be provided in conjunction with the printing press, in which the film application module is integrated. Then it can be arranged for example in the sheet delivery of the printing press or a last printing unit.

The transport of the transfer film 5 can be monitored on or between film guide rollers 14 by checking the web tension of the film web 5. In a film web guide one or more web tension measuring devices 19 are provided for this purpose.
Furthermore, a stabilization device 30 can be arranged to stabilize the film web 5 between a first deflection roller and a first inlet roller to the transfer unit in order to reduce flapping movements of the film web 5. The stabilizing device 30 has z. B. two rotatably mounted rollers, which is provided for the variable setting of the wrap angle of the film web 5 on the guide rollers, so that the guiding action and the damping effect on the film web 5 is adjustable depending on the operating state. The adjustment of the stabilization device 30 can be carried out in conjunction with means for web tension control 19 and possibly a sensor device 20 for web break monitoring.

1. 1. Ein Bahnzug oberhalb eines vorgebbaren Minimalwerts wird als Signal für Vorhandensein der Folienbahn 5 gewertet und der Maschinensteuerung zugeführt.
2. 2. Ein Überschreiten des Maximalwerts des vorgebbaren Bahnzugs wird über Tänzerwalzen 18 oder Rollenantriebe 7 der Folienvorrats- 8 bzw. -sammelrolle 9 reduziert. Damit sind unzulässige Bahndehnung oder Bahnriss vermeidbar.
3. 3. Bei Unterschreiten des minimal vorgebbaren Bahnzugs wird überprüft, ob die Bahnspannungsregelung noch aktiv ist. Ist eine Erhöhung der Bahnspannung über Tänzerwalzen 18 oder eine Bremse nicht möglich, wird Bahnriss erkannt.

Electrical signals of the web tension measuring devices are evaluated. Various operating states are possible for this:

1. 1. A web train above a predetermined minimum value is evaluated as a signal for the presence of the film web 5 and fed to the machine control.
2. 2. Exceeding the maximum value of the predeterminable web train is reduced by means of dancer rollers 18 or roller drives 7 of the film supply 8 or collecting roller 9. Thus, impermissible web elongation or web break can be avoided.
3. 3. If the minimum specified tension is undershot, it is checked whether the web tension control is still active. If it is not possible to increase the web tension by means of dancer rollers 18 or a brake, web break is detected.

The additionally obtained information about the web tension as the actual value, in particular in the context of the aforementioned evaluations, can be used for the control of the printing or transfer process. For this purpose, the system can be coupled to a control station of the printing machine, via which the setpoint values for maximum and minimum web tension can be entered. This may depend on the type of transfer film 5 used and on the printing or transfer conditions in the coating module 2 in connection with the properties of the printing material, the adhesive or the press fabric.
The necessary data can be read via interfaces directly from data carriers to film supply rolls and changed by means of parameter values from the setting of the transfer process on the coating module 2.

The method relating to the film transfer is described in the described printing or application machine according to FIG. 1 as follows:
It is intended, at least in a printing unit 50 following the coating unit 2, to apply a color print to the printed image sheet coated with a metallized layer. Here, the sheet from the coating unit 2 is transferred from the impression cylinder 4 via a sheet transfer drum or a sheet transfer unit to a counter-pressure cylinder 40 of the printing unit 50.
The printing unit 50 has, as usual in offset printing units, the counter-pressure cylinder 40, an associated rubber or blanket cylinder 41 and a plate cylinder 43 associated therewith. The plate cylinder 43 are here shown schematically an inking unit and a dampening unit assigned.

Between counter-pressure cylinder 40 and blanket cylinder 41, a further pressure gap 60 is formed. In this printing gap 60 ink is applied from a spanned on the plate cylinder 43 printing plate 44 via a arranged on the blanket cylinder 41 cover 42 on the sheet.

The gap of the printing gap 60 between the surfaces of the blanket cylinder 41 and the impression cylinder 40 is adjustable by means of the printing blanket cylinder 41 associated adjusting devices 45. In this case, in the area of offset printing, it is customary to speak of a printing provision, since the setting referred to relates to the thickness of the printing material to be processed, which is to be printed in the printing nip 60. For this purpose, a printing pressure is necessary to transfer the ink from the blanket cylinder 41 to the held on the impression cylinder 40 substrate.
The adjustments with respect to the transfer nip 6 are made by means of further actuators 46 associated with the press roll 3.
The actuators 45, 46 are commonly used in offset printing on printing blanket or blanket cylinders of printing units or on cylinders of varnish modules.

Furthermore, should be provided as a surface of the press roll 3 a contoured or segmented pressing surface in the press fabric 10. For this purpose, instead of a full-surface pressing area on one or more areas to be coated limited segmented pressing areas are used on the press roller 3.
The segmented pressing surface may be formed as an isolated surface element, as an annular, narrow surface element encircling the press roll 3, as a surface line following a limited peripheral portion covering over the width of the press roll 3 reaching surface element or in the form of several such surface elements pronounced and so the press fabric 10 form. For this purpose, for example, a cut-out printing blanket, an imageable plastic high-pressure mold or a pressure pad to be fastened on a smooth base, possibly adhesively attachable or magnetically attachable, can be used to support the segmented pressing surface. One at its bottom with a magnetic adhesive surface provided Andrucksegment can be placed for example directly on the surface of the press roller 3. On the other hand, a magnetic film can be clamped onto the surface of the press roll 3, to which then a contact pressure segment with a magnetically adhering rear side can be placed for affixing or positioning the segmented press surface 10. The surface and the inner structure of the Andrucksegmentes should correspond to the information described above in terms of elasticity and smoothness. Here, a compressible pad may be provided which carries a preferably smooth relatively firm functional position.

The function of this limited segmented pressing surface in the press fabric 10 is that - similar to the passage of a cylinder channel of the press roll 3 and the opposite impression cylinder 4 - the entrapment of the transfer film 5 is given only if the segmented press surface the transfer film 5 touching the transfer nip. 6 passes. In other words, the pressing surface should only be able to act on the transfer film 5 in the areas where actually imaging layers are to be transferred from the transfer film 5 to the printing sheet.

1. I. Zunächst kann zur Ausführung einer Folientaktung die Transferfolie 5 neben dem Zeitraum des Kanaldurchlaufes in sehr vorteilhafter Weise auch dann im Vorschub angehalten werden, wenn der zu beschichtende Bereich irgendwo innerhalb des Bildbereiches des Druckbogens liegt und noch nicht den Bereich der segmentierten Pressfläche erreicht hat oder der Bereich der segmentierten Pressfläche schon vor dem Ende des zu beschichtenden Bogenbereiches endet. Die Transferfolie 5 muss also nur dann transportiert werden, wenn die segmentierte Pressfläche innerhalb des Transferspaltes 6 zwischen Presswalze 3 und Gegendruckzylinder 4 im Eingriff ist. So kann die Ausnutzung der Transferfolie 5 zwischen den zu beschichtenden Druckbogen fast vollständig erfolgen.
   Der Folientransport wird hierbei beim Einsatz einer ringförmigen Pressfläche nur beim Kanaldurchlauf angehalten.
   Beim Einsatz von Pressflächen in Form einzelner oder mehrerer, zylinderbreiter, über Teilumfänge reichender Segmente kann der Folienvorschub zusätzlich während freier Flächen am Umfang der Presswalze 3 angehalten werden.
2. II. Eine weitere Verbesserung der Folienausnutzung der beschriebenen Art ergibt sich dadurch, dass die Transferfolie 5 in eine oder mehrere Teilfolienbahnen geringerer Breite aufgeteilt wird. Die ist insbesondere in Verbindung mit der segmentierten Pressfläche von großem Vorteil. Bei einer segmentierten Pressfläche kann die Transferfolie 5 auf die Breite der Pressfläche beschränkt eingesetzt werden. Die Einsparung beim Folienverbrauch ist bedeutend. Die Folienführung im Transferspalt 6 wird durch eine vollflächige Auflage einer schmalen Bahn der Transferfolie 5 auf der segmentierten Pressfläche - zumindest im Transferspalt 6 - deutlich verbessert.
   Damit kann bei entsprechender Steuerung mit Hilfe der Einrichtung bzw. Einrichtungen zur Taktung des Folienvorschubes jeder der Teilfolienbahnen, die Ausnutzung der Transferfolie 5 auch bei zonal unterschiedlich langen Beschichtungsbereichen innerhalb eines Bogens verbessert werden. Dazu wird jede Teilfolienbahn nur genau in dem Bereich weitergefördert, wo die bildgebende Oberflächenschicht aufzutragen ist. In den nicht zu beschichtenden Bereichen kann jede Teilfolienbahn unabhängig von den anderen Teilfolienbahnen stillgesetzt werden, wobei damit kein unnötiger Folienverbrauch entsteht.

Thus, two effects can be achieved in a coating module 2 with a segmented pressing surface provided in a press fabric 10:

1. I. First, to carry out a film timing, the transfer film 5 can be stopped in advance in a very advantageous manner in addition to the period of the channel passage, if the area to be coated is located somewhere within the image area of the sheet and has not yet reached the area of the segmented pressing surface, or the area of the segmented pressing surface ends before the end of the arch area to be coated. The transfer film 5 therefore only has to be transported if the segmented pressing surface is in engagement within the transfer nip 6 between the press roll 3 and the impression cylinder 4. Thus, the utilization of the transfer film 5 between the sheets to be coated can be almost complete.
   The film transport is stopped here when using an annular pressing surface only at the channel pass.
   When using pressing surfaces in the form of single or multiple, cylinder-wide, over Teilumfänge reaching segments of the film feed can be additionally stopped during free areas on the circumference of the press roll 3.
2. II. A further improvement of the film utilization of the type described results from the fact that the transfer film 5 is divided into one or more Teilfolienbahnen lesser width. This is particularly advantageous in connection with the segmented pressing surface. In a segmented pressing surface, the transfer film 5 can be used limited to the width of the pressing surface. The savings in film consumption is significant. The film guide in the transfer nip 6 is significantly improved by a full-surface support of a narrow web of transfer film 5 on the segmented pressing surface - at least in the transfer nip 6.
   Thus, with appropriate control by means of the device or devices for timing the film feed each of the sub-film webs, the utilization of the transfer film 5 can be improved even in zonally different lengths coating areas within a sheet. For this purpose, each partial film web is conveyed only exactly in the area where the imaging surface layer is to be applied. In the areas not to be coated, each partial film web can be stopped independently of the other partial film webs, whereby no unnecessary film consumption arises.

In combination with the above-mentioned method, it is thus also possible to use different types of film side by side. This allows surfaces of different film color or different smoothness or texture to be created.

• gestripptes Gummituch, bei dem die druckende Oberfläche aus Gummi bis auf die beim Prägen zur Wirkung zu bringende Fläche entfernt wurde
• polymere Schneidplatte (Klischee für Flexodruck), die mittels Flachbettplotter herstellbar und ggf. mit Träger aus Aluminium oder Polyester ausgerüstet ist
• eine Fotopolymerplatte (Flexodruck), deren Oberflächenkontur mit Belichtung und Auswaschen herstellbar ist (ggf. mit Träger aus Aluminium).
• Verwendbar ist auch ein Gummituch mit einem Metallträger, das sich wie ein gestripptes Gummi- bzw. Drucktuch vorbereiten und einsetzen lässt.

For the construction of the partial press fabric, different working materials known per se can be used. Can be used

• Stripped rubber blanket with the rubber surface removed except for the area to be embossed
• polymeric cutting plate (cliché for flexographic printing), which can be produced by means of a flatbed plotter and is optionally equipped with a carrier made of aluminum or polyester
• a photopolymer plate (flexographic printing), whose surface contour can be produced with exposure and washing out (possibly with aluminum support).
• It is also possible to use a rubber blanket with a metal carrier that can be prepared and used like a stripped rubber or blanket.

As a substructure of the corresponding press fabric 10 with segmented pressing surfaces is a pad with or without damping effect, such as a vacuum blanket (but only in press clothing without rigid support layer) used.

Clamping systems in the cylinder channel of the press roll 3 for attaching the press fabric 10 may be tensioning spindles such as in a blanket cylinder or combination clamping rails for blankets or printing plates, as known from the rubber or the form cylinder. The surface of the press fabric 10 is suitable depending on the structure for profiled imprints. This results in an extended range of applications for the process of cold foil stamping.
Using the above elements, a very simple and fast handling of the device of the film application module is possible.

• eine Kanaltaktung beim Durchlauf von Zylinderkanälen der Presswalze 3 und des Gegendruckzylinders 4,
• eine Formattaktung bei auf die Formatlänge des Folientransfers am Umfang der Presswalze 3 beschränkter Folienzuführung und
• eine Prägebereichstaktung bei Beschränkung der Folienführung auf durch segmentierte Pressbereiche in der Pressbespannung 10 der Presswalze 3 definierter Folienzuführung

angeführt werden.
Für die Folienzuführung (auch die Abführung) ist üblicherweise der Antrieb der Folienrollen 8, 9 kontinuierlich vorgesehen, da die Masse der Folienrollen 8, 9 zu groß für einen schnellen Wechsel der Antriebsbewegung ist. Dadurch ergeben sich beim Abbremsen der Folienbahn bis zum erneuten Beschleunigen im Transferbereich in den Zu- und Abführbereichen der Folienbahn 5 gegenüber der Bewegung der Folienrollen 8, 9 überschüssige oder fehlende Folienlängen.According to the invention devices are provided which allow the cyclic promotion of the film web 5. Here, as operating variants from the previously executed

• a channel timing in the passage of cylinder channels of the press roll 3 and the impression cylinder 4,
• a formattaktung limited to the format length of the film transfer on the circumference of the press roll 3 film feed and
• a Prägebereichstaktung when limiting the film guide on segmented pressing areas in the press fabric 10 of the press roll 3 defined film feed

be cited.
For the film supply (and the discharge) is usually the drive of the film rolls 8, 9 continuously provided, since the mass of the film rolls 8, 9 to great for a quick change of drive movement. This results in braking the film web to re-accelerating in the transfer area in the supply and discharge of the film web 5 relative to the movement of the film rolls 8, 9 excess or missing film lengths.

Therefore, solutions are proposed according to the invention, which can buffer the resulting in continuous Nachförderung or removal of the film web 5 excess or missing pieces of web. These are basically already described with the dancer rollers 18 as a variant of foil stores. However, the dancer rolls 10 are not sufficiently controllable on the described in the described high-speed clocking in the film transfer process, especially since they are usually far away from the place of consumption and close to the film roll 8, 9 to maintain the web tension there.
In the FIGS. 2 to 5 Therefore, further possibilities for the rapid compensation of web displacements in the film timing in the cold foil process are given.

In FIG. 2 is a film transfer module accordingly FIG. 1 shown. Here, the dancer rollers 18 are arranged to regulate the web tension. To compensate for major changes in the film promotion, such as stopping the film transfer in the transfer area (range of film transfer between press roll 3 and impression cylinder 4) without film consumption (channel timing, format clocking, timing on embossed areas), are also in front of the inlet of the fresh film web 5 in the Transfer nip 6 and after the exit of the used film web 5 from the transfer nip 6 as drive groups 22 designated roller pairs 23, 24 are arranged.

The drive groups 22 are described here for all subsequent embodiments and each show a pair of rollers that can pinch the film web 5 and thus defined in terms of a desired transport path can lead. The pairs of rollers of the drive groups 22 are made in FIG. 2 each of a film guide roller 24 and a drive roller 23. Both the film guide roller 24 and the drive roller 23 is at least partially driven. The drive of the drive roller 23 can not only in the transport direction of the film web 5 (of film roll 8 to 9), but may also generate return strokes. This makes sense, since the film web 5 does not stop immediately when decelerating and thus runs over a desired breakpoint. As a result, a piece of the film web 5 could not be used. A short defined return stroke after braking and stopping the film web 5 in the transfer area reduces or eliminates this unnecessary film consumption. For this purpose, the drive of the drive roller 23 can be controlled quickly. The drive roller 23 itself can be segmented in order to be able to execute the changing drive movements quickly. Furthermore, the film guide roller 24 with respect to the drive roller 23 can be pivoted up and down, but it can also be permanently employed on the drive roller 23.

Thus, it can also be provided that the film guide roller 24 perform a more or less controlled by the film web 5 movement, while the drive roller 23 performs a conveying movement and the return stroke movement. The film guide roller 24 performs for a defined period in relation to the film transport direction a backward movement only by controlled hiring against the resting on the drive roller 23 film web 5. The drive roller 23 then performs a continuous transport movement against the direction of the film web 5. This is possible because the film web 5 is freely movable at this time due to lack of contact pressure by the press roller 3 against the impression cylinder 4 in the transfer area.
Furthermore, the drive groups 22 can also hold the film web 5 in the transfer area under the necessary tension by braking at the time of sheet breakage, in this case at least on the feed side to the transfer nip 6, thus immediately upon restart of the film transfer with pressing by the press roller 3 against the impression cylinder 4 good transfer quality is achieved again.

The system of the drive group 22 is also suitable for segmented film guide rollers 24 in format width drive rollers 23 both for the guidance of a full-width film web 5 as well as for the guidance of, if necessary distributed distributed, partial film webs 5 suitable. For this purpose, the segments of the film guide roller 24 can be arranged correspondingly adjustable to the positions of the partial film webs 5 in the axial direction to the press roller 3.

The drive group 22 can be simplified by designing the drive roller 23 with a rough or adhesive surface or as a suction roller. With a correspondingly large looping through the film web 5, sufficient adhesion for the secure guidance of the film web 5 on the drive roller 23 can then be achieved. Then it would be possible to dispense with a foil guide roller 24, even in segmented form. This is also harmless in terms of the format-width design of the drive roller 23. A drive roller 23 designed as a suction roller could then be designed in such a way that suction devices which can be switched as needed in segments corresponding to the respective film web widths to be processed are provided if required.

According to FIG. 2 Thus, it is provided to carry out the film timing in the transfer area by means of the drive groups 22 with respect to the film storage by means of the dancers 18.1, 18.2. The dancer 18.1 in the region of the feed roller 8 takes on in the transfer area stationary film web 5 under the action of the web tension sensor located there, the film piece, which is released by the clamping of the film web 5 by means of the drive group 22. At the same time, the dancer 18.2 releases a piece of film for the film winding, since then no film web 5 is conveyed after. With renewed onset of the film promotion after the end of the interruption of the film promotion in the transfer area, the sequence of film release and film storage runs on the dancers 18.2, 18.1 in each case vice versa.

In FIG. 3 a simplified embodiment in a coating unit 2 is shown. Here, on the one hand, the dancers 18 are shown, which are to serve only the web tension control.
Furthermore, a drive group 22 is again provided in the region of the film feed to the transfer area with the transfer nip 6. On the outlet side from the transfer area, a pendulum-held foil guide roller 25 is shown. This film guide roller 25 can perform a directed transversely to the course of the transport direction of the film web 5 compensating movement. The compensation movement is marked with a dashed representation. Thus, the path of the film web 5 is extended and shortened. If the drive group 22 so the film web Retains 5 for clocking or feed back, the film guide roller 25 can perform a compensating movement to shorten the web path and thus release a piece of film web to compensate for this movement against the Abförderbewegung. If the promotion of the film web to start again, the film guide roller 25 performs a movement to extend the path of the film web 5 down. Thus, the film web 5 is accelerated again or released in the acceleration by releasing the drive group 22 track piece can be compensated.

In FIGS. 4 and 5 variants of the storage effects in the film timing are shown, which use a per se known principle of looping the film web by applying a negative pressure film memory 26.1, 26.2, 27.1, 27.2,28.1 and 28.2 are each assigned to one side of the coating unit 2. The film stores 26.1, 27.1 and 28.1 are respectively associated with the feed side of the film web 5 to the transfer nip 6 and thus the feed roller 8. The film stores 26.2, 27.2 and 28.2 are each associated with the discharge side of the film web 5 away from the transfer nip 6.

Each film store 26.1, 26.2, 27.1, 27.2, 28.1 and 28.2 consists of a vacuum chamber into which a film loop 29 of the film web 5 is guided in and out again.
The effect of the film reservoirs 26.1, 26.2, 27.1, 27.2, 28.1 and 28.2 is as follows: By sucking air (for example by means of one or more fans) on the bottom side of the vacuum chambers, the film loop 29 is in each case provided with a force that adjusts itself according to the negative pressure Injected negative pressure chamber. This force does not outweigh the predetermined by the web tension control tensile force of the film web 5, since the film loops 29 would otherwise be firmly sucked in the vacuum chambers. The system is self-regulating insofar as the film loops 29 can freely oscillate in the chamber against the force of the negative pressure and thus receive or release each foil web pieces. Since the system of the film memory 26.1, 26.2, 27.1, 27.2, 28.1 and 28.2 is freely oscillating, more drive groups have to be provided here than in the previously described systems.

To regulate the film web promotion, the formation of the size of the film loops 29 (36, see Fig. 6 ) be used. For this purpose, a sensor may be provided in each of the vacuum chambers, which is formed approximately on the basis of the distance measurement by means of ultrasound. This sensor detects how far the film loop 29, 36 is formed or how far the film loop 29, 36 is drawn into the vacuum chamber. On the basis of these constantly measured signals can then be regulated by means of the drives of the film rolls 7, 8 and possibly in conjunction with dancer rolls the film web conveying.

1. a) Zum Anhalten Folientransfers und damit auch des Folientransportes im Transferbereich (Transferspalt 6) wird durch das Stillsetzen der Antriebsgruppe 22 vor dem Transferspalt 6 bei laufender Folienrolle 7 eine auflaufende Folienbahnlänge frei und in den ersten Folienspeicher 26.1, 27.1, 28.1 oder 32.1 hineingezogen.
2. b) Auf der Ablaufseite nach dem Transferbereich wird gleichzeitig die Folienbahn 5 aus dem zweiten Folienspeicher 26.2, 27.2, 28.2 oder 32.2 zur kontinuierlichen Aufwicklung freigegeben.
3. c) Zum Fortsetzen des Folientransfers und damit dem erneuten Einsetzen des Folientransportes im Transferbereich wird die Antriebsgruppe wieder aktiviert und die eingezogene Folienschlaufe 29 aus dem ersten Folienspeicher 26.1, 27.1, 28.1 oder 32.1 wieder dem Transferbereich zugeführt.
4. d) Gleichzeitig wird der zweite Folienspeicher 26.2, 27.2, 28.2 oder 32.2 wieder mit einer Folienschlaufe 29, 36 befüllt.

The two-sided arrangement of the film stores 26.1, 26.2, 27.1, 27.2, 28.1 and 28.2 (also 32.1, 32.2 in Fig. 6 ) serves that the timing of the film web feed when stopping and continuing the film transport in the transfer area can be performed as follows:

1. a) To stop film transfers and thus also the film transport in the transfer area (transfer nip 6) by pulling the drive group 22 in front of the transfer nip 6 with running film roll 7 a running film web length freely and in the first film memory 26.1, 27.1, 28.1 or 32.1 drawn.
2. b) On the discharge side after the transfer area, the film web 5 is simultaneously released from the second film store 26.2, 27.2, 28.2 or 32.2 for continuous winding.
3. c) To continue the film transfer and thus the reinsertion of the film transport in the transfer area, the drive group is activated again and fed the film loop 29 fed from the first film memory 26.1, 27.1, 28.1 or 32.1 back to the transfer area.
4. d) At the same time, the second film store 26.2, 27.2, 28.2 or 32.2 is again filled with a film loop 29, 36.

According to FIG. 4 Two variants for the arrangement of foil stores 26.1, 26.2, 27.1 and 27.2 are shown.
At the bottom of the film transfer module of the coating unit 2 small film storage 26.1 and 26.2 are shown. These are with the drive groups 22nd the transfer area at the transfer nip 6 combined. In addition, the film stores 26.1, 26.2 each foil guide rollers 14 are assigned to guide the film web 5.
At the top of the film transfer module of the coating unit 2 larger film storage 27.1 and 27.2 are shown. These are combined with their own drive groups and possibly with drive groups 22 of the transfer area at the transfer gap 6. In addition, the film stores 27.1, 27.2 are each associated with film guide rollers 14 for guiding the film web 5. The foil stores 27.1, 27.2 associated drive groups 22 are used to hold the film web 5 when the negative pressure at the film stores 27.1, 27.2 collapses or other disturbances occur in the film promotion. In addition, with these drive groups 22, a further control option for the railway conveying.

The system of film stores 26.1, 26.2 is built smaller, so better integrated and responsive because of its small volume. With this system, so smaller fluctuations in the film web promotion can be compensated quickly and effectively and also serves the same timing.
The system of film stores 27.1, 27.2 is built larger, thus receptive and can compensate for larger fluctuations in the film web promotion. This is suitable for a timing that has to bridge large spaces when film transfer, so if only short areas of film 5 are to be transferred to the circumference of the press roll.

In FIG. 5 is a variant with foil stores 28.1 and 28.2 shown in a coating unit 2, which allows even larger storage. The film stores 28.1, 28.2 are placed vertically and assigned directly to the drive groups 22 of the transfer area at the transfer nip 6. As a result of the vertical arrangement, the feed of the film web 5 from the film loop 29 in the film store 28.1 can be fed to the transfer area directly and without a film guide device of the first drive group 22 on the feed side. Likewise, the film web 5 on the discharge side of the transfer region without film guide elements on the film storage 28.2 whose film loop 29 are fed. In FIG. 5 are two Folienleitwalzen 14 for discharge from the housing of the coating plant 2 shown. On the feed side of the film storage 28.1 and the discharge side of the film storage 28.2 roller pairs 14 are shown, which serve as pinch rollers for better guidance of the film web 5. The one film roll can in turn be designed as a drive roller 24 in order to be able to control the film web conveyance here as well.

In FIG. 6 In accordance with the previously described functionalities, a further variant with foil stores 32.1 and 32.2 is shown in a coating unit 2 which has a compact construction and allows larger stores. The film storage 32.1 is arranged approximately horizontally downstream under the film roll 7 and the film storage 32.2 is placed approximately perpendicular to the opposite side. The drive group 33 with two film guide rollers 35 and a drive roller 34 on the inlet side of the transfer area is assigned close to the transfer nip 6. The drive group 33 with a film guide roller 35 and a drive roller 34 on the discharge side of the transfer nip 6 is associated with the film storage 32.2. Due to the horizontal arrangement, the feeding of the film web 5 from the film loop 36 in the film memory 32.1 can be arranged compactly and fed via a smoothing and stabilizing device 30 of the first drive group 33 on the feed side to the transfer area (transfer nip 6). For feeding and removing the film web 5 to and from the film storage 32.1 Folienleitwalzen 31 are provided to keep the film web 5 easily movable.
Furthermore, the film web 5 on the discharge side of the transfer area after the transfer nip 6 on the film web 5 smooth holding foil guiding elements 14 (in the manner of a smoothing and stabilizing device) are performed. These film guiding elements 14 also guide the film web 5 out of the area of the printing unit protection 15 on the coating unit 2. On the discharge side after the transfer region to the film storage 32.2 can also be arranged a drive group 37, which has a film guide roller 38 and a drive roller 39. To form a film loop 36 in the film storage 32.2, the film web 5 is fed without additional guide. The removal of the film web 5 from the film storage 32.2 via a film guide roller 31st

On the feed side and the discharge side of the film storage 32.1 and on the discharge side of the film storage 32.2 a film guide roller 31 is shown, which serve to better guide the film web 5, so that the film web the film storage 32.1 exactly fed and kept smooth from the film storage 32.2 for winding is dissipated.
Alternatively, the drive group 37 for the discharge side of the film web 5 may be arranged on the film guide roller 31 on the film storage 32.2. For this purpose, because of the large wrap the film guide roller 31 itself be driven or it can also be assigned to this a further drive roller.

The drive groups 22, as well as the film guide roller 25 FIG. 3 , can also be combined with suction rollers. Then the clamping of the film web is not so critical. The control of the suction air to such suction rolls but is run at a very high clock frequency.

The vacuum chambers of the film stores 26.1, 26.2, 27.1, 27.2, 28.1, 28.2, 32.1 and 32.2 can be designed according to the leading to film or partial film webs. If the vacuum chambers have the width of a film web and are displaceable, it is possible to respond flexibly to desired coating conditions.
Furthermore, separating devices which cover the lateral position of the film web 5 or partial film webs can be arranged in the work area overlapping vacuum chambers. Thus, the film storage 26.1, 26.2, 27.1, 27.2, 28.1, 28.2, 32.1 and 32.2 can be divided advantageously into several parallel vacuum chambers. If separating devices can be inserted into the vacuum chambers and / or are displaceable in the vacuum chambers transversely to the running direction of the film or partial film webs 5, it is thus possible to provide width-adjustable and separate vacuum chambers. These are tunable to individual film webs 5 of different widths or partial film webs of the same or different widths. Thus, the formation of film loops 29, 36 is improved and tailored to each leading to foil or Teilfolienbahnen.

When covering individual, not occupied by a film web 5 chambers of the air consumption of the vacuum device can be minimized and better regulated.

It has been shown that the suction at the vacuum chambers of the film stores 26.1, 27.1, 28.1, 32.1 on the feed side to the transfer area can also serve to clean the film webs. In particular, particles which adhere to the web edge (mica, dust, contamination) are sucked into the vacuum chambers and removed via the suction devices. Therefore, it is advantageous if at least one filter device is provided in the vacuum supply of the vacuum chambers, which serves to separate the contaminants. This can be done simultaneously with the storage of film loops 29, 36 and a cleaning of the film web, so that the transfer process runs undisturbed and the coating unit 2 is kept clean.

The arrangement of the film storage 26.1, 26.2, 27.1, 27.2, 28.1, 28.2, 32.1 and 32.2 and the drive groups 22, 33 may be designed so that they are interchangeable in existing film transfer devices against dancer. Thus, a more efficient film guide for existing systems can be retrofitted in a simple manner.

The film guide can also be interrupted when the press roller 3 has an only partially occupied pressing surface, so that the film web can be stopped during the passage of not occupied with a pressing surface areas in the transfer nip 6.

The film supply and removal can be performed with controllable or self-regulating systems such as friction shafts and individual drives on the film rolls 8, 9 in the variants of a format-wide film roll or with multiple sub-film rolls.

LIST OF REFERENCE NUMBERS

1

commissioned

2

coating module

3

press roll

4

Impression cylinder

5

Transfer foil / foil web

6

transfer nip

7

roller drive

8th

Film supply roll

9

Foil composite role

10

Press covering

11

Inking / dampening unit

12

plate cylinder

13

Blanket / blanket cylinder

14

Folienleiteinrichtung

15

Printing plant security

16

dryer

17

Inspection device / monitoring system

18

dancer roll

19

Bahnspannungsüberwachungl

20

Web break monitoring

21

Druckzylinderblasvorrichtung

22

drive group

23

Folienleitwalze

24

drive roller

25

Folienleitwalze

26.1

film storage

26.2

film storage

27.1

film storage

27.2

film storage

28.1

film storage

28.2

film storage

29

Loop / foil loop

30

stabilizing device

31

Folienleitwalze

32.1

film storage

32.2

film storage

33

drive group

34

drive roller

35

Folienleitwalze

36

Loop / foil loop

37

drive group

38

Folienleitwalze

39

drive roller

40

Impression cylinder

41

Blanket cylinder

42

Blanket / blanket

43

plate cylinder

44

printing plate

45

setting device

46

setting device

50

printing unit

60

nip

Claims (10)

1. Apparatus to transfer image layers from a carrier film to printed sheets in a sheet offset printing press with at least one coating station (1) for an image coating of the printed sheets with an adhesive and with a coating module (2) to transfer image layers from the carrier film to the printed sheet within a transfer slot (6) between an impression cylinder (4) and a press role (3), wherein the carrier film with the coated side can be guided, while in contact with the printed sheet together with this, through the transfer slot (6), wherein the image layers can be transferred in an image-conform manner to the printed sheet, and with a device to feed the transfer film (5) to the coating station (2) and to discharge it from the coating station (2) with a drive to move the transfer film in the operating direction, wherein the film feed of the transfer film (5) can be controlled by means of a device for film guidance in such a way that the transfer of the transfer film (5) is then stopped if no transfer of an image layer to a printed sheet takes place within the transfer slot (6) of the coating station (2), that a control in connection with a film guidance of the transfer film (5) is provided in such a way that when passing through a gripper of a cylinder channel (22) of the press roll (3) accommodating the sheet-guiding impression cylinder (4), the film feed is stopped, wherein the press roll (3) continues to run through still being in contact with the transfer film (5) in a sliding manner and/or that press fabric (10) with an elevated outline-contoured press surface is provided as the surface of the press cylinder (3), wherein the press surface is limited to the area to be maximally coated of the film feed and that, when passing through an area of the press roll (3) outside of the press surface limited to the area to be coated, the film feed is stopped, wherein the press roll (3) runs through in a sliding manner while still in contact with the transfer film (5), wherein controllable conveyor devices are assigned to the film web (5) to slow down and accelerate in sync with the processing of the film transfer, characterized in that the conveyor devices (22, 33) are designed as roller pairs, each consisting of a film guide roller (24), as well as the drive roller (23), wherein the roller pairs guide the film web (5) in a gripping manner and the film guide roller (24) and the driver roller (23) can be driven, that the conveyor devices (22, 33) are assigned to a transfer area before and after the transfer slot (6) and that film accumulators (26.1, 26.2, 27.1, 27.2, 28.1, 28.2, 32.1, 32.2) are assigned to the conveyor devices (22, 33), wherein the film accumulators (26.1, 26.2, 27.1, 27.2, 28.1, 28.2, 32.1, 32.2) are each designed as vacuum chambers accommodating at least one film loop (29, 36) of the film web (5), which are set up to suck air by means of one or a plurality of fans on the bottom side.
2. Apparatus according to Claim 1, characterized in that the transfer film (5) is divided into one or a plurality of partial film webs with a small width and that the partial film webs are fed to the transfer slot (6) in a positioned manner and adjacent to one another, wherein the partial film webs are provided with identical image layers or image layers that differ from one another and layers having a different colour and/or different gloss and/or different surface structure can be produced.
3. Apparatus according to Claim 1 to 2, characterized in that the conveyor devices (22, 33) are assigned to a transfer area before the transfer slot (6) or before
   and after the transfer slot (6) respectively and that film accumulators (26.1, 26.2, 27.1, 27.2, 28.1, 28.2, 32.1, 32.2) are assigned to conveyor devices.
4. Apparatus according to Claim 1 to 3, characterized in that the film accumulators (26.1, 26.2, 27.1, 27.2, 28.1, 28.2, 32.1, 32.2) are designed as vacuum chambers accommodating one or a plurality of film loops (29, 36) of a film web (5) or a plurality of partial film webs, wherein the vacuum chambers have one or a plurality of separating devices to delimit vacuum areas at the width of one or a plurality of film or partial film webs.
5. Apparatus according to Claim 4, characterized in that the vacuum chambers have suction devices to generate a vacuum, wherein, adhesive substance residues of the film web(s) (5) can be sucked up by means of one or a plurality of suction devices and that filter devices are assigned to the suction devices to separate the adhesive substance residues.
6. Method to coat printed sheets in a sheet offset printing press by means of an apparatus according to Claim 1 under the use of a transfer film (5) consisting of image layers and a carrier film to transfer image layers from the carrier film to the printed sheets, wherein

   - at least an image coating of a printed sheet takes place using a coating station (1) by means of an adhesive and

   - by means of a coating module (2), a transfer of the image layers from the carrier film to the printed sheets takes place, wherein, in the coating module (2), an impression cylinder (4) and a press roll (3) have a joint transfer slot (6), through which the transfer film (5) can be led under pressure in such a way that it is placed with its coated side onto the printed sheet led on the impression cylinder (4),

   - wherein, after the printed sheet has left the transfer slot (6), the image layer(s) bond to the printed sheet in the area of the image areas provided with adhesive and is lifted from the carrier film, wherein the transfer film (5) is pressed against the printed sheet at least in the area of the image coating(s) within the transfer slot (6) and

   - wherein the transfer film (5) is only conveyed through the transfer slot (6) if a contact between the surface of the press roll (3) and the printing substrate lying on the impression cylinder (4) is established, characterized in that

   - before being fed into the transfer slot (6), the transfer film (5) can be stored in the first film accumulator while being gradually fed during a step where no conveyance of film takes place, whereby, before the transfer slot (6), the transfer film/ webs (5) are led into vacuum chambers forming film accumulators with film loops under the influence of a vacuum and

   - the transfer film is conveyed before going into the transfer slot (6) by a roll pair (23, 24) forming a drive group (22)

   - and that the transfer film (5) is conveyed by a roll pair (23, 24) forming a drive group (22) after being discharged from the transfer slot (6), and

   - after being discharged from the transfer slot (6), the transfer film (5) can be conveyed out of a second film accumulator while being gradually fed during a step where no conveyance of film takes place

   - wherein, after the transfer slot (6), the transfer film/ webs (5) are led into vacuum chambers forming film accumulators with film loops under the influence of a vacuum.
7. Method according to Claim 6, characterized in that one or a plurality of proof segments are introduced on the press roll (3) that have a press surface, the surface of which is adapted to the surface area of the image coatings, and that the transfer film (5), viewed axially to the press roll (3), is only fed to the transfer slot (6) in the area of axis sections provided with press surfaces.
8. Method according to Claim 6 or 7, characterized in that, on the press roll (3), one or a plurality of proof segments are introduced, the press surface of which is adapted to the surface area of the image coatings, and that transfer film (5), viewed in the circumferential direction toward to the press roll (3), are fed to the transfer slot (6) only in the area of the circumferential sections provided with press surfaces.
9. Method according to Claim 6 to 8, characterized in that the transfer film (5) is fed to the transfer slot (6) step by step in to the axis sections, in which press surfaces (21) are laid out.
10. Method according to Claim 6, characterized in that the transfer film (5) in the film accumulators is cleaned by means of suction devices of the vacuum chambers provided.

Images