EP2004408B1 - Stamping foil unit - Google Patents

Abstract

The device has a machine cover (10) with a smooth or very fine structure provided on a surface of a transfer cylinder (3). The cylinder is formed and/or dimensioned and/or moved in connection with the cover that is laid on the surface of the cylinder. A velocity is reached at an effective surface of the transfer cylinder and lies about 3 percentage by a surface velocity of a cylinder cooperating with the transfer cylinder. The cover on the surface of the transfer cylinder has a modified packing thickness for adaptation of the surface velocity of the transfer cylinder.

Description

The invention relates to a device for transferring imaging layers from a carrier film to printing sheet according to the preamble of patent claim 1.

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, between which two units printing units and a film transfer module are arranged. 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 film transfer module with a counter-pressure cylinder and a transfer cylinder, 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 film transfer module between the impression cylinder and the transfer cylinder by a film supply roll. The film strip is rewound on the exit side after leaving the film transfer module. The transfer film has a carrier layer on which imaging layers such as metallic layers, for example of aluminum, can be applied. When printing sheets are transported through the printing unit, each sheet is given an adhesive pattern. Thereafter, the sheet is passed through the film transfer module, wherein by means of the transfer cylinder, the resting on the impression cylinder sheet is brought into contact with the film material. In this case, the downwardly lying metallic layer enters into a close connection with the areas provided with adhesive on the printed sheet. After further transporting the printing sheet, the metallic layer adheres only in the area provided with the adhesive pattern. The carrier film thus becomes the metallic layer in the region of the adhesive pattern taken. The used in this way transfer film is wound up again. The print sheet is laid out in the coated state. From the WO 2005/100024 is a printing machine with a stamping device known. In the printing machine, a film feed is shown in a coating module for transfer of imaging layers from a transfer film to a printing substrate. The transfer film is preferably passed in the coating module approximately tangentially to a press roll.

Furthermore, from the WO-A-2005/049322 a method and apparatus for combination pressure known. Here printed products are coated in a process step in a film printing process at predetermined positions with a film and provided in another process step in a structure and / or embossing process with a structure and / or embossing.

It is known to use such film transfer modules, for example in printing units of printing presses. A disadvantage of the known devices is that they are not flexible and that the consumption of transfer film is expensive.

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 can be done safely, economically and accurately, the device should be easy to handle.

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

Advantageously, a transfer method is used to guide the transfer film, in which the transfer film is processed during the film transfer by means of the transfer cylinder with an increased supply pressure.

In a further embodiment, the surface of the transfer cylinder may be provided with an elevated pressing surface contoured in outline, which is limited to the region to be coated. For this, a cut-out blanket, a plastic printing form or a stick-on press-on segment is suitable. Thereby, the feed of the transfer film can be stopped in a very advantageous manner, even if the area to be coated is within the image area of the sheet.

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

Figur 1

eine grundsätzliche Darstellung einer Druckmaschine mit einer Fo- lientransfereinrichtung,

Figur 2

den Aufbau eines Transferzylinders in einer Folientransfereinrich- tung und

Figur 3

den Aufbau einer Pressbespannung.

Showing:

FIG. 1

a basic representation of a printing press with a film transfer device,

FIG. 2

the construction of a transfer cylinder in a film transfer device and

FIG. 3

the structure of a press fabric.

In FIG. 1 is a sheet-processing machine, here a printing press, shown, which consists of at least two printing units.

A sheet to be coated is provided in a first step in the applicator 1 with an imaging adhesive pattern. For this purpose, a printing unit of an offset printing press with inking and dampening units 11, a printing plate on a plate cylinder 12, a blanket or blanket cylinder 13 and a counter-pressure cylinder 4 can be used. Likewise, applicators can be used in the form of flexographic printing or painting units.

In the second step, a transfer film 5 is guided under pressure through a transfer nip 6 together with the printing sheet. A film transfer module 2 used for this purpose may be a printing unit, a paint module, a base unit or another type of processing station of a sheet-fed offset printing press.

The transfer nip 6 in the film transfer module 2 is formed by a transfer cylinder 3 and an impression cylinder 4. The transfer cylinder 3 may correspond to a blanket or form cylinder of a known offset printing unit or paint module of a sheetfed offset printing press. Within the film transfer module 2, a web guide for transfer films 5 is shown.

A film supply roll 8 is assigned to the film transfer module 2 on the page of sheet feeding. The film supply roll 8 has a rotary drive 7. The rotary drive 7 is required for the continuous controlled feeding of the transfer film 5 to the film transfer module 2 and is therefore controllable.

Furthermore, in the field of film feed and removal guide devices 14, such as deflection or tensioning rollers, pneumatically actuated conducting means, baffles o. Ä. Provided. Thus, the film web of the transfer film 5 can always be guided flat without distortions and held in the same voltage with respect to the transfer cylinder 3.

In this case, the transfer film 5 can be guided around the transfer cylinder 3, wherein the transfer film 5 can advantageously be fed in and out of the press nip 6 only from one side of the film transfer module 2 (see dashed representation). In a further embodiment, the transfer film 5 can also be fed in and out substantially tangentially on the transfer cylinder 3 or wrap it around only in a small circumferential angle to the press nip 6. For this purpose, the transfer film 5 is supplied from one side of the film transfer module 2 and discharged to the opposite side of the film transfer module 2. On the outlet side of the printing unit, a film collection roller 9 is shown, is wound up by the used sheet material. Again, a rotary drive 7 is provided, which is controllable.

Furthermore, to improve the coating process provided in the area of the adhesive application and in the area of the film order dryer 16 provided. Thus, in particular by means of UV drying, the imagewise applied adhesive layer can be predried by means of a first dryer 16 (intermediate dryer I) so that the wear layer of the transfer film 5 adheres better. Furthermore, the adhesive effect of the applied wear layer on the printed sheet can be improved by the action of a second dryer 16 (intermediate dryer II) by additionally accelerating the drying of the adhesive.

For the transfer process of the imaging eg wear layer of the transfer sheet 5 on the sheet in the transfer nip 6 between the transfer cylinder 3 and the impression cylinder 4 is essential that the surface of the transfer cylinder 3 so the blanket cylinder or forme cylinder is equipped by means of a compressible, damping element. The transfer cylinder 3 is therefore provided with a press fabric 10 or as a roller with a corresponding coating. The press fabric 10 or press coating can be performed, for example, as a plastic coating, comparable to a blanket or blanket. The surface of the press fabric 10 is preferably very hard and smooth. It can be made of antiadhesive substances or structures. The press fabric 10 is held on the transfer cylinder 3 in a cylinder channel on jigs.

The press fabric 10 may be equipped to improve the transmission properties in the transfer nip 6 with a targeted elasticity. This may optionally act in a compressible intermediate layer. This compressibility is preferably similar or less than in conventional blankets or Drucktüchem that can be used at this point.

The mentioned compressibility can be produced by means of a conventional compressible printing blanket. Furthermore, combined fabrics made of a hard blanket and a soft pad can be used. Furthermore, a limited, segmented pressing surface 21 may be provided on the transfer cylinder 3 or the press fabric 10 instead of a full-surface pressing surface 20.

For this purpose, for example, a cut-out printing blanket, an imageable plastic high-pressure mold or a pressure-releasing segment 22, which can preferably be adhesively fastened or magnetically attached to a smooth base, the segmented pressing surface 21 can be used to support it. A pressure pad 22 provided with a magnetic adhesive surface on its underside may e.g. be placed directly on the surface of the transfer cylinder 3. On the other hand, a magnetic film can also be clamped onto the surface of the transfer cylinder 3, to which a contact pressure segment 22 with a magnetically adhering rear side can then be placed to mount or position the segmented pressing surface 21. The surface and the internal structure of the Andrucksegmentes 22 should correspond to the information described above in terms of elasticity and smoothness. In this case, a compressible blanket pad 23 may be provided which carries a preferably smooth relatively firm functional layer 24.

However, the associated device fundamentally includes a corresponding feed control for the transfer film 5, which ensures that at least the film piece lying between the transfer cylinder 3 and the impression cylinder 4 is stationary as long as the cylinder channel 19 passes through.

In the FIGS. 2 and 3 is a section through a transfer cylinder 3 and by the press fabric 10 and the reference on the surface of the transfer cylinder 3 is shown. The transfer cylinder 3 is provided with a press fabric 10, for example as a plastic coating, comparable to a blanket or blanket. The press fabric 10 is held in a cylinder channel 19 at clamping devices.

The press fabric 10 is equipped to improve the transmission properties in the transfer nip 6 with a targeted elasticity. This may optionally act in a compressible intermediate layer. This compressibility is preferably similar or less than in conventional blankets or blankets, which can also be used at this point.

A different kind of compressibility can be produced by means of a conventional compressible printing blanket. Furthermore, combined fabrics made of a hard blanket and a soft pad can be used. Preferably, a press fabric 10 is made of a blanket having a relatively thin, hard surface, which consists of a plastic coating as a functional layer 24. This functional layer 24 is provided with a compressible substructure consisting of a compact elastic material or of closed-cell or open-cell foam. Only below should the force-transmitting layer, for example a fabric layer, be arranged. Thus, with high flexibility of the surface, nevertheless a very high strength of the printing blanket or press fabric 10 is achieved. This has the particular advantage that the adaptation of the transfer film 5 to the respective substrate surface or the applied adhesive succeeds particularly well.

The surface of the press fabric 10, for example of the plastic coating 14 should be as smooth as possible. The plastic coating 14 has a low surface roughness with a surface roughness in the range of 1 micron or smaller. The material of the press fabric 10 has the lowest possible adhesion to the material of the carrier film of the transfer film 5.

Although the surfaces of blankets are very smooth in themselves, but they often have a kind of cut pattern from the processing and are on the other hand also equipped to accept ink. Therefore, in this way, for example, the transfer film may adhere to conventional blankets. This in turn can lead to damage during transfer of the imaging layer from the transfer sheet 5 to the printed sheet B.

By means of the plastic surface of the press fabric 10, which has a low adhesion to the transfer sheet 5, a clean transfer of the imaging layer is made possible on the sheet, since the transfer sheet 5 fixed by the press fabric 10 per se only against the sheet and by means of adhesion to the Gluing is performed on the sheet. Then the synchronization of the film web is tuned, so that no shifts in the splice can occur.

By a, as described, elastic construction of the press fabric 10, a very flexible transfer nip 6 is generated. Furthermore, an enlargement of the transfer nip 6 in the direction of a relatively flat extension is generated by a diameter, for example, of the counter-pressure cylinder 4 that is twice the size of the transfer cylinder 3. In this case, to produce an optimum transfer pressure in the transfer nip 6, a somewhat higher pressure provision can be selected between the transfer cylinder 3 and the impression cylinder 4 than is necessary in a conventional printing process. For example, allowable values of 0.10 mm to 0.14 mm can be used compared to a standard value of 0.10 mm.

To improve the film transfer is provided in the context of the described arrangement to achieve an adaptation of the peripheral speed of the effective surface of the transfer cylinder 3 to the nature of the press fabric 10 and the film properties of the transfer film 5. In this case, a compensation of the indentation depth of the press fabric 10 in the transfer nip 6 is to be achieved in view of the effective during the layer transfer in the transfer nip 6 speed ratios.

1. 1. Der Gegendruckzylinder 4 gibt eine Grundgeschwindigkeit für den Folientransferprozess vor.
2. 2. Der Druckbogen B ist liegt glatt auf der Oberfläche und durch Greifer fixiert am Gegendruckzylinder 4 auf, so dass die Oberflächengeschwindigkeit des Druckbogens B, die eigentliche Transfergeschwindigkeit definiert.
3. 3. Synchron mit der Oberflächengeschwindigkeit des Druckbogens B muss die Transferfolie 5 zu- bzw. abgeführt werden.
4. 4. Die Oberfläche des Transferzylinders 3 bildet mit der Oberfläche des Gegendruckzylinders 4 den Transferspalt 6.
5. 5. Die wirksame Oberfläche des Transferzylinders 3 ist hinsichtlich ihrer Lage durch die Art und Dicke 25 der Packung der Pressbespannung 10 bestimmt.
6. 6. Da der Gegendruckzylinder 4 selbst, sowie der Druckbogen B und die Transferfolie 5 sich quasi als Kontinuum bewegen, stellen für den Schichttransfer im Transferspalt 6 die Bewegung und die Lage der Oberfläche des Transferzylinders 3 die einzigen Variablen dar.
7. 7. Die Oberfläche des Transferzylinders 3 muss hinsichtlich ihrer Lage durch Veränderung der Position des Transferzylinders 3 gegenüber dem Gegendruckzylinder 4 an die durch Gegendruckzylinder 4, Druckbogen B und Transferfolie 5 definierte Bezugsfläche angepasst werden, wobei eine Komprimierung der Pressbespannung 10 einzurechnen ist.
8. 8. Je nach Dicke 25 der Pressbespannung 10, deren Komprimierung im Transferspalt 6, sowie der Relativlage von Gegendruckzylinder 4 und Transferzylinder 3 ergeben sich unterschiedliche Geschwindigkeitsverhältnisse zwischen der wirksamen Oberfläche des Transferzylinders 3 und der an ihm vorbei geführten Transferfolie 5.

For the speed ratios to be taken into account here are the following conditions:

1. 1. The impression cylinder 4 provides a basic speed for the film transfer process.
2. 2. The sheet B is smooth on the surface and fixed by gripper on the impression cylinder 4, so that the surface speed of the sheet B, the actual transfer rate defines.
3. 3. Synchronous with the surface speed of the sheet B, the transfer sheet 5 must be added or removed.
4. 4. The surface of the transfer cylinder 3 forms the transfer nip 6 with the surface of the impression cylinder 4.
5. 5. The effective surface of the transfer cylinder 3 is determined in terms of their location by the type and thickness 25 of the packing of the press fabric 10.
6. 6. Since the counter-pressure cylinder 4 itself, as well as the printing sheet B and the transfer sheet 5 are moving as a kind of continuum, the movement and the position of the surface of the transfer cylinder 3 are the only variables for the layer transfer in the transfer nip 6.
7. 7. The surface of the transfer cylinder 3 must be adjusted in terms of their position by changing the position of the transfer cylinder 3 relative to the impression cylinder 4 to the defined by counter pressure cylinder 4, sheet B and transfer sheet 5 reference surface, with a compression of the press fabric 10 is to be included.
8. 8. Depending on the thickness 25 of the press fabric 10, their compression in the transfer nip 6, and the relative position of impression cylinder 4 and transfer cylinder 3, different speed ratios between the effective surface of the transfer cylinder 3 and guided past him transfer sheet fifth

First, a change in the surface or peripheral speed on the transfer cylinder 3 can be achieved by a development change on the transfer cylinder 3. For this purpose, the press fabric 10 can be up to 2.8 ‰ above the nominal diameter of a normally covered transfer cylinder 3 is reinforced. This then means that z. B. at a nominal diameter of 300 mm, an increase in the packing thickness 25 of the press fabric of 0.84 mm compared to the nominal diameter.

This results in constant Druckbeistellung the transfer cylinder 3 with respect to the impression cylinder 4, a corresponding minimum difference in speed taking into account the change in diameter on the transfer cylinder 3 by the Druckbeistellung with corresponding flattening of the press fabric in the transfer nip 6. This setting causes the transfer sheet 5 held smoothly, safely in Transfer gap 6 out and pressed so that the imaging layer is transferred crack-free on the sheet.

It may be advantageous if the surface of the press fabric 10 of the transfer cylinder 3 is very smooth and without - as known from conventional blankets ago - grinding pattern is executed. Furthermore, here also a very low compressibility of the press fabric can be advantageous to bring the comparatively small deviations safely in the transfer nip 6 to the effect. In this case, the known compression of the press fabric 10 in the transfer nip 6 can be safely controlled.

Under these conditions, the same effect in the film transfer in the transfer nip 6 finally can also be achieved by means of a device for speed superposition, which can be assigned to the transfer cylinder 3. For this purpose, the transfer cylinder 3 can preferably be provided with a special drive.

For this purpose, on the one hand, transmissions can be used which can be designed, for example, in the form of superposition transmissions. For example, so-called harmonic drive gearboxes come into question. Also conceivable are other continuously adjustable superposition gear as link chain transmission.

Likewise, on the other hand, an independently controllable direct drive can be provided on the transfer cylinder 3.

The adaptation of the circumferential speed of the surface of the transfer cylinder 3 with respect to the actual transport speed in the transfer nip 6 should in this case be in the range of about 0 to + 3.5 ‰.

An advantage of the last-mentioned possible solutions is that it results in a variable adjustability of the desired differential speed, without the need for a conversion of the press fabric 10 on the transfer cylinder 3 would be necessary.

Furthermore, the differential speed can be adjusted during operation even with changing conditions such as fluctuating process temperatures or changing operating speeds. For this purpose, control mechanisms may be provided on the transfer module 2.

In addition, an adaptation of the web tension conditions to the respective available film quality should be possible. Thus, the most favorable web tension for transfer foils with a thickness of 15 μm is in the range of 10 to 45 Nm with a variation of +/- 10%.

However, it may be expedient to set these values of the web tension of the transfer film 5 as a function of the production process of the transfer film 5 used in each case and to provide them generally adjustable only to the extent of the values thus determined.

An adjustment of the web tension above the value set during the production can lead to a stretching and additional loading of the carrier film 5 and the transfer coating, as well as the adhesion between the two layers. Possibly. can make massive changes to the transfer sheet 5 or cracks in the transfer layer.

Furthermore, an adjustment of the web tension below the value set during production can lead to insufficient spreading and tightening of the carrier film 5. This can cause the risk that the transfer film 5 does not run straight into the transfer nip 6.

About the nature of the press fabric 10 has already been reported above. Essential is a uniform closed surface, so preferably a full-surface arrangement of the press fabric. The surface should be very smooth and preferably have no microsection. The compressibility is to be kept at a low level. The surface may be formed of polymers. The hardness of the press fabric can be in the range of 60 to 90 Shore.

In the case of the stated materials and settings, the transfer cylinder 3 assumes a transport function for the transfer film 5 such that it is no longer preferably in the transfer nip 6 under the tension of the web tension control. On the contrary, due to the minimal speed difference, the transfer cylinder 3 conveys the transfer film 5 into the transfer nip 6, so that the image-forming layer can be transferred there almost free from tensile stress and applied to the printing material without cracking.

LIST OF REFERENCE NUMBERS

1

commissioned

2

Foil transfer module

3

transfer cylinder

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

Color / Feuchwerk

12

plate cylinder

13

Blanket cylinder

14

guide

15

Verschutzung

16

UV dryer

17

monitoring system

18

dancer roll

19

cylinder gap

20

Press area

21

segmented pressing surface

22

Andrucksegment

23

Blanket support

24

functional position

25

packing thickness

Claims (15)

1. A device for the transfer of imaging layers from a carrier foil which jointly form a transfer foil (5) on to print sheets at least with one application system (1) for image coating of a print sheet with an adhesive and with a foil transfer module (2) for transferring the imaging layers from the carrier foil on to the print sheet, wherein the foil transfer module. (2) contains an impression cylinder (4) and a transfer cylinder (3) which form a joint transfer gap (6), and wherein furthermore the carrier foil can be guided about the transfer cylinder (3) or approximately tangentially past the transfer cylinder (3) in such a manner that it is placed with the coated side on the print sheet guided on the impression cylinder (4) and under pressure jointly with the print sheet is guided through the transfer gap (6) between transfer cylinder (3) and impression cylinder (4) and wherein the imaging layers after the emergence of the print sheet from the transfer gap (6) in the region of the image regions provided with adhesive adheres to the print sheet and is lifted off the carrier foil,
   characterized in
   that on the surface of the transfer cylinder (3) a compressable, damping covering (10) is provided and that the transfer cylinder (3) in conjunction with the covering (10) resting on the surface is so designed or dimensioned and/or driven that on the defective surface of the transfer cylinder (3) a speed is obtained which is up to 3.5 ‰ above the surface speed of the impression cylinder cooperating with the transfer cylinder (3) which is obtained on said impression cylinder in the transfer gap (6) with the inclusion of the medium to be coated and the transfer foil (5) resting on said medium.
2. The device according to Claim 1,
   characterized in that
   the covering resting on the surface of the transfer cylinder (3) comprises a variable packing thickness (25).
3. The device according to Claim 2,
   characterized in that
   the covering on the surface of the transfer cylinder (3) is established through a press clothing (10) in conjunction with variably combinable supports.
4. The device according to Claim 2 or 3,
   characterized in that
   the covering (10) on the surface of the transfer cylinder (3) comprises a changed packing thickness (25) so that an effective diameter of the transfer cylinder (3) of up to 0.9 mm above its rated diameter with normal packing thickness (25) is obtained.
5. The device according to Claim 1 to 4,
   characterized in that
   the transfer cylinder (3) under inclusion of the supports is provided with a smooth press clothing (10) of low compressability and that the surface of the covering (10) at least in the region of the contact with the transfer foil (5) has minimum adhesion relative to the carrier foil.
6. The device according to Claim 1 to 4,
   characterized in that
   the press clothing (10) comprises a function layer which is formed by means of a material of lower surface tension, wherein its surface is smoothed and that the press clothing (10) comprises a compressable substructure (23).
7. The device according to Claim 1 to 6,
   characterized in that
   the press clothing (10) is detachably mountable on the transfer cylinder (3) as surface element covering the full area of the cylindrical surface region of the transfer cylinder (3) in the foil transfer module (2).
8. The device according to Claim 1 to 7,
   characterized in that
   the transfer cylinder (3) in the foil transfer module (2) is assigned a device for the continuously and remotely adjustable controllable changing of the centre distance of the transfer cylinder (3) to the cylinder guiding the print material and arranged adjacent to the transfer cylinder (3) for forming the transfer gap (6).
9. The device according to Claim 1 to 8,
   characterized in that
   the transfer cylinder (3) comprises a drive or is connected with a drive in such a manner that by means of the drive the surface speed of the effective surface of the transfer cylinder (3) relative to the surface of the transfer foil (5) placed on the cylinder cooperating with the transfer cylinder (3) or print material guided thereupon can be changed, preferably increased.
10. The device according to Claim 9,
    characterized that
    in a drive connection between and with a drive of the machine processing sheets or the foil transfer module (2) and the transfer cylinder (3) a gear with continuously adjustable gear ratio is provided.
11. The device according to Claim 9,
    characterized in that
    a separate drive motor mechanically arranged in front of the drive of the foil transfer module (2) with continuously adjustable drive speed is assigned to the transfer cylinder (3).
12. The device according to Claim 9 to 11,
    characterized in that
    a regulating device is provided by means of which a differential speed of the effective surface of the transfer cylinder (3) relative to the cylinders cooperating with said transfer cylinder and forming the transfer gap (6) is variably adjustable as a function of the machine speed.
13. The device according to Claim 9 to 11,
    characterized in that
    a control device is provided by means of which the differential speed of the effective surface of the transfer cylinder (3) relative to the cylinder cooperating with said transfer cylinder and forming the transfer gap (6) together with said transfer cylinder is variably adjustable dependent on a value of the web tension measured on the transfer foil (5).
14. The device according to Claim 9 to 11,
    characterized in that
    a control device is provided by means of which the differential speed of the effective surface of the transfer cylinder (3) relative to the cylinder cooperating with said transfer cylinder and forming the transfer gap (6) dependent on a value of the pressure setting between the transfer cylinder (3) and the cylinder adjacent to said transfer cylinder taking into account the thickness (25) of a cover mounted on the transfer cylinder (3) is variably adjustable.
15. The device according to Claim 9 to 11,
    characterized in that
    a control device is provided by means of which the differential speed of the effective surface of the transfer cylinder (3) relative to the cylinder cooperating with said transfer cylinder and forming the transfer gap (6) as a function of temperature changes occurring in the foil transfer module (2) or on the transfer foil (5) is variably adjustable.

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