EP2386412B1 - Film timing - Google Patents

Description

The present invention relates to a film transfer device comprising a commissioning unit for at least regional application of a guided through the applicator substrate with an adhesive, the applicator downstream transfer unit with a transfer gap for at least regional transferring a transfer layer of a carrier film, which together form a transfer sheet, on the substrate , wherein the transfer nip is formed by a transfer cylinder and an impression cylinder, the transfer film is at least partially guided around the transfer cylinder and the transfer cylinder has a channel.

Generic film transfer devices are used in the refinement of printed products, for example, to produce gloss effects. The machines can be subdivided into hot stamping foil machines and cold foil stamping machines. In the latter, the transfer layer is applied to the sheet material, i. H. transferred to a substrate such as a sheet only under pressure, but not additionally under the action of heat. As a rule, in the case of a cold foil transfer device, i. H. Cold foil stamping devices with a printing unit, which is upstream of the transfer device, printing adhesive so that a printed image of adhesive remains on the sheet, which can deduct a corresponding transfer layer of the transfer film used within a film transfer station, so that this transfer layer partially adhered to the sheet. In this case, the transfer layer can be partially transferred in the transfer nip under the action of pressure substantially in the regions applied with adhesive.

The problem with this film transfer technique is that the transfer film must be moved at the same speed as the substrate during the transfer and that usually only small areas on the substrate to be covered with the transfer layer. In particular, a transfer cylinder involved in the transfer nip often has a so-called channel in which a blanket can be fastened. In the area of this channel can not transfer by means of pressure from the Transfer layer done. Therefore, should always be regulated so that the substrate dips into the transfer gap between the transfer cylinder and a counter-pressure cylinder when the channel can not be in the range of the printing material. Other areas where transfer film is transported unused through the transfer nip are areas in which no transfer layer is to be transferred onto the substrate.

For better use of the transfer film and to reduce consumables, it is z. B. according to the EP 932501 B1 provided to move the transfer film over a pair of dancer rollers, which move cyclically in common with the channel of the transfer cylinder, so that the transfer film is braked in the region of the channel to a speed of zero, for example. For this purpose, the two dancer rollers are coupled together so that transfer film web, which is stored by the still moving supply roll from a first front dancer, is released by a second rear dancer simultaneously to the collecting roller. In this way, a certain constancy of the web tension can be ensured in the storage and collecting role. For this purpose, to save the transfer film both dancers are moved coupled in a braking direction. In particular, the film can also be withdrawn from the transfer nip.

The problem with such devices with concurrent dancers is when the transfer cylinder is enclosed by the transfer film and has rotated so far that the transfer film before the transfer gap can already dip into the channel while the transfer film behind the transfer gap is still fully employed on the transfer cylinder and this wraps around. A dancer roller which is arranged downstream of the transfer gap does not see anything of the channel already acting on the film due to the adjustment of the transfer cylinder to the impression cylinder. A dancer roller which is provided in front of the transfer gap, however, already "notices" the existing channel. The front and rear dancer roller are essentially decoupled from each other by the transfer nip. While the web tension in the area of the rear dancer roller remains constant, it already decreases on the side of the front dancer roller.

Similar effects occur when the channel is already employed with its rear edge to the impression cylinder.

Whenever the front and rear dancer rolls are decoupled from each other, different web tensions occur on both sides. In addition, there is a general collapse of the web tension on both sides when the channel is in the area of the transfer nip.

To tackle this problem of changing web tension is in the DE 10 2009 020 106 A1 have been proposed to decouple the dancer waves from each other and move asynchronously to each other so as to compensate for the different web tension changes before and after the channel.

However, it still remains problematic that there are at least brief changes in the position and the tension of the film in the channel itself. As a result, in particular when the film is to be withdrawn against the advancing direction of the sheet during the clocking, the speed with which the film can be transferred to a printed sheet is considerably reduced. This results inter alia from the fact that, in particular during the retraction of the film, this at least briefly applies to the edge region of the channel and so can be carried along by this channel. Depending on the direction of movement of the film that happens on all edge regions of the cylinder channel and also on the surfaces of the cylinder channel cover. This entrainment of the transfer film through the edge region of the channel leads to considerable impairment of the web tension itself. In order to ensure proper functioning of the film transfer, therefore, the speed of the channel, d. H. the rotational speed of the impression cylinder and the blanket cylinder can be reduced to prevent damage to the film.

The object of the present invention is therefore to show a film transfer device with which a higher clocking speed can be achieved.

This object of the invention is achieved by a film transfer device according to the preamble of claim 1, wherein in an area, i. H. More specifically, in a peripheral region of the channel of the transfer cylinder, a coating is provided which is adapted to increase the adhesion of the transfer film back to this edge region of the channel, i. H. here on the transfer cylinder, at least reduced. In this way, the film slides better on the edge region of the channel and a higher clocking speed can be achieved because the engagement of the edge region of the channel is reduced in the film. The effects on the tension of the transfer film are thereby reduced to such an extent that no damage to the transfer film itself is to be expected even at higher rates of clocking.

In further embodiments of the film transfer device, it is provided that this coating can be provided both on the edges of the channel and additionally or alternatively on the top of a channel cover of the channel. In particular, it can always be provided only in the edge regions of the channel cover and the channel. The coating is provided for this purpose preferably axially over the entire width of the transfer cylinder or at least in the regions in which the transfer film contacts the transfer cylinder.

It may in particular be a strip which can also be subsequently glued on the edge and / or on the channel cover.

As possible adhesive strips which are adhered to the channel cover and / or on the edge of the channel, in particular crepe paper or a non-stick paper can be provided. It may also be a surface of the blanket of the transfer cylinder itself. The transfer cylinder should in particular have a substantially smooth surface and have a deviating surface structure exclusively in the regions of the channel, which has a corresponding coating for reducing the friction with the transfer film. It may be in the materials of the non-stick paper or the surface of the blanket z. B. act on silicone or PTFE.

Since such coatings of the printing blanket can have an effect on the film transfer itself, which are undesirable since they can be recognized in the printed image, it is particularly advantageous to provide this coating or the strip which is glued or otherwise applied to the transfer cylinder. in the circumferential direction, d. H. in its width, substantially to a region of the edge of the channel which can not or should not come into contact with a region of the printing material which should be coated or printed. In this way, the effect of this coating or this strip on the substrate in a resulting printed image is not visible.

This strip according to the invention can advantageously be designed as an adhesive strip but also other holding options, such. As magnetic or electrostatic process, are conceivable here.

Figur 1

eine schematische Skizze des Aufbau eines Folientransferwerks mit Taktung,

Figur 2

eine Folientransfervorrichtung mit einem entsprechenden Folientransferwerk und

Figur 3

eine Darstellung eines Randbereichs eines Transferzylinderkanals.

An embodiment of the invention, from which further inventive features may result but to which the invention is not limited, is shown in the following drawings. Show it:

FIG. 1

a schematic sketch of the structure of a film transfer station with clocking,

FIG. 2

a film transfer device with a corresponding film transfer unit and

FIG. 3

a representation of an edge region of a transfer cylinder channel.

In the FIG. 1 a film transfer unit 1 is shown in which a transfer film 2 is passed through a transfer nip 3.

The transfer nip 3 is formed by a transfer cylinder 5 and an impression cylinder 4. The transfer film 2 is unwound from a supply roll 7 and pulled by a front advantage 9 in the direction of the transfer nip 3. The supply roll 7 is located on a friction shaft, not shown here, and is provided with a Speed is driven, which is less than the speed of the printing material 21. The drive of the supply roll 7 via the friction shaft. The transfer sheet 2 is withdrawn from the supply roll 7 by the front-end 9, the rolls of the front-end 9 being driven at a higher speed than the friction shaft of the supply roll 7. However, the front-end 9 is still operated at a lower speed than the speed of the printing material 21.

The unwound transfer film 2 is guided through the transfer nip 3 via a front dancer 13 of a timing module 11 and via further deflection rollers 6 in such a way that it forms a wrap angle α with the transfer cylinder 5. Behind the transfer nip 3, the transfer film 2 is further guided over deflection rollers 6 and fed to a rear dancer 12, which deflects the transfer film 2 and a rear advantage 10 feeds, which is faster than the front advantage 9. By the rear advantage 10, the film is the second directed to the collecting roller 8. Also, the collecting roller 8 is mounted on a friction shaft, which is driven faster than the rear advantage. At least the friction shaft is driven so that the peripheral speed of the collecting roller 8 is greater than the speed of the rear preferred 10. In this way, there is a slip between the friction shaft and the actual collecting roller 8. The same applies to the supply roll. 7

A printing material 21 is passed through the impression cylinder 3 together with the transfer film 2 via the impression cylinder 4. In the transfer of a transfer layer, not shown here, transfer sheet 2 and substrate 21 are at a same speed.

The transfer cylinder 5 has a blanket, which is not further shown here, which is clamped by a channel 20, wherein the channel 20 is also provided to accommodate possible grippers on the side of the impression cylinder 4 can.

If the front edge 113 of the channel 20 comes into the transfer nip 3, the web tension between the dancer 13 and the transfer nip 3 collapses. During the Transfer of a transfer layer to the substrate 21, the sum of the speed of the front preferred 9 and the front dancer 13, the speed of the printing material 21. For this purpose, the dancer 13, which along a path which is indicated by the double arrow 16 in an acceleration direction 18 moves , By contacting the front edge 113 of the channel 20 with the impression cylinder 4, the front 13 is decoupled from the rear dancer 12. In order to compensate for the intruding web tension now, it is provided that the front dancer 13 is driven by a motor 15 so that it is first accelerated sharply in the braking direction 19. As a result, a constant web tension is achieved in this area. For this purpose, a control device 22 acts on the motor 15 of the front dancer 13 accordingly. If the channel 20 is completely in the area of the transfer nip 3, then the dancer 13 is moved at a lower acceleration in the direction of the braking direction 19, so that the transfer film 2 comes to a standstill or is withdrawn.

If the channel 20 is "seen" by the dancer 12 for the first time, the rear dancer 12 is first accelerated at a lower acceleration in the direction of the braking direction 19 in order to compensate for this break-in and later accelerated at a higher speed, so that a standstill of the transfer film 2 is achieved can be. Again, the controller 22 is connected to the motor 14 of the rear dancer.

The FIG. 2 shows a section of a film transfer device 100. Such a film transfer device 100 may be constructed within a printing press. A sheet 21 is transported through a commissioning unit 101, which is a conventional printing unit of a printing press through a printing nip 109 therethrough. In this printing gap 109 of the substrate 21 is partially applied with adhesive. The sheet 21 is then transported further through the film transfer unit 1. As described, the sheet 21 is passed through the transfer nip 3, in which it decreases the transfer layer of the transfer sheet 2 in the areas of the transfer sheet 2, to which it is itself applied with adhesive.

The thus treated sheet 2 can then continue through the printing machine, i. H. be transported through the film transfer device, that it is moved to another subsequent printing unit 103, which again has a printing gap 109, which is formed by a blanket cylinder 110 and a counter-pressure cylinder 111. The printing unit 103 also has an inking unit 112. In the printing unit 103, the sheet 21 acted upon by the transfer layer can then be conventionally overprinted.

In the FIG. 3 a section of a transfer cylinder 5 is shown. This section shows the rear edge 114 of the channel 20 of the transfer cylinder 5. The transfer cylinder 5 shown here further has a channel cover 200 on. This channel cover is conventionally provided in transfer cylinders 5 and also in conventional blanket cylinders 110 in printing units 103 or applicators 101, as this reduces the engagement area for operators, so that there may be less damage to persons, and further by this channel cover 200th even the fluctuations of the transfer film 2 is reduced.

The transfer cylinder 5 here has a covering with a blanket, d. H. a blanket, 201 on. This is in particular a particularly smooth blanket, for example a so-called Irioblanket ™. This blanket 201 is held in the channel 20 both in the region of the front edge 113 and the rear edge 114 by clamping devices 202.

At a timing of the transfer film 2, this dips at least in the subregion 203 of the channel 20 and can then turn around here in particular when retracting the transfer film 2 to the rear edge 114. If the transfer film 2 is moved relative to the transfer cylinder in a feed movement in the direction of arrow 204 opposite to the withdrawal, it may lead to a corresponding transfer of the transfer film 2 around the edge 205 of the channel cover 200. The front region of the channel 20 in the region of the front edge 113 is constructed symmetrically to the rear region shown here, and thus when the transfer film 2 is advanced in the direction of the arrow 204, the front edge 113 of the channel 20 is wrapped accordingly.

As shown here, both the channel cover 200 and the rear edge 114 and also the front edge 113 (not shown here) are symmetrically loaded with a strip 206. The channel cover 200 is completely covered with the strip 206, while the rear edge 114 is symmetrically applied to the front edge 113 with the strip 206 so that the blanket 201 is occupied only in a portion 207 with the strip 206. The strip 206 is intended to terminate shortly behind the rear edge 114 or the front edge 113, so that no strip 206 is provided here in the region of the beginning of the print 208. In this case, the term "print start 208" refers to the region of the transfer cylinder 5 in which a transfer layer can be transferred from the transfer film 2 to the sheet 21.

In the example presented here, the strip 206 is a masking tape which has a surface finish which reduces the friction between the rear side of the transfer film 2 and the blanket 201 or the channel cover 200, so that it does not adhere to the transfer film 2 the rear edge 114 of the channel 20, at the front edge 113 of the channel 20 or in a region 205 of the channel cover, which limits the timing speed of the film transfer device or the film transfer unit 1. The strip 206 may in particular be incorporated into the blanket 201, but is preferably aufklebbar due to the retrofit. As an alternative to masking tape can also be used a strip which made of PTFE, silicone or a non-stick paper, such as. B. is common in the oven area, is modeled.

By means of this coating element, which can simply be applied subsequently, ie by the strip 206, a considerable increase in the speed of the film transfer 1 can be achieved.

LIST OF REFERENCE NUMBERS

1

Film transfer unit

2

transfer film

3

transfer nip

4

Impression cylinder

5

transfer cylinder

6

idler pulley

a

Wrap angle

7

supply roll

8th

composite role

9

front delay

10

rear delay

11

timing module

12

back dancer

13

front dancer

14, 15

Engines

16, 17

double arrows

18

acceleration arrow

19

brake arrow

20

channel

21

bow

22

control device

100

Foil transfer device

101

commissioned

102

transfer unit

103

printing unit

105

transfer nip

106

transfer cylinder

107

Impression cylinder

109

nip

110

Blanket cylinder

11.1

Impression cylinder

112

inking

113

front edge

114

rear edge

200

channel cover

201

blanket

202

tensioning device

203

subregion

204

feed motion

205

Area of the channel cover

206

strip

207

subregion

208

print scope

Claims (7)

1. Foil transfer device comprising
   an application unit (101) for at least regionally applying glue to a printing material (21) that is guided through the application unit (101),
   a transfer unit (1) arranged downstream of the application unit (101) and including a transfer nip (3) for at least regionally transferring a transfer layer from a carrier foil, which together form a transfer foil (2), onto the printing material (21),
   the transfer nip being formed by a transfer cylinder (5), an impression cylinder (4) and the transfer foil (2) being at least partly guided around the transfer cylinder (5), and the transfer cylinder (5) including a gap (20),
   characterized in
   that the transfer cylinder includes an essentially smooth surface and a coating (206) at least reducing adhesion of the rear side of the transfer foil to the transfer cylinder (5) is provided exclusively in the region (113, 114, 205) of the gap (20).
2. Foil transfer device according to Claim 1,
   characterized in
   that the coating (206) is provided at at least one edge (113, 114) of the gap (20) and/or on the top side (205) of a gap cover for axially covering the gap (20) relative to the axis of the transfer cylinder essentially over the width of the transfer foil (2).
3. Foil transfer device according to Claim 2,
   characterized in
   that the coating is provided in the form of a strip (206) on the edge (113, 114) and/or on the gap cover (200).
4. Foil transfer device according to Claim 3,
   characterized in
   that the strip (206) is a crepe paper or a non-stick paper or comprises a surface made of one of the materials silicone and PTFE.
5. Foil transfer device according to Claim 2 or 3,
   characterized in
   that in terms of its width, the coating (206) or the strip is essentially limited to a region (207) of the edge (113, 114) of the gap (20) that does not get into contact with a region (108) of the printing material (21) that was coated in an upstream unit (101) or in the transfer unit (1).
6. Foil transfer device according to Claim 5,
   characterized in
   that the transfer cylinder (5) has a covering in the form of a printing blanket (201)/rubber blanket and the coating or strip (206) is applied to the surface of the printing blanket (201)/rubber blanket in the region (207) of the gap edges (113, 114).
7. Foil transfer device according to Claim 3,
   characterized in
   that the strip (206) is designed as an adhesive strip.

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