EP1593503B1 - Foil guiding device for a flat foil printing machine - Google Patents

Description

The invention relates to a film web guide for a flat embossing machine with film webs, which are guided by unwinding rollers on an embossing table according to the preamble of claim 1. With such flat embossing machines particularly high embossing performances in the best quality and for particularly demanding embossing tasks such as relief embossing can be performed. On the other hand, these flat embossing machines also place particularly high demands on the guidance and precise preference of the thin and very sensitive embossed foil webs, with layer thicknesses of, for example, only 12-20 μm (0.02 mm).
Several film webs of different types (with different web widths, preferred lengths and with different detachment forces of the film webs depending on the embossing order) at the same time smoothly smoothly guided and promoted. The film guide must be perfectly smooth and accurately positioned without distortion, hull formation, wrinkles and dislocations flat. And the quick, intermittent advantage over the entire embossing table in a short time must be performed optimally gentle, in order to achieve high performance and quality. Such a flat embossing machine and film web guide is for example from the EP 0 858 888 known. The film web guide has before the embossing table to a tensioning roller, in which necessarily two deflection rollers on the embossing layer side of the film webs are required, which can affect the sensitive embossing layer. Moreover, here are the tensile stresses for several Film webs only limited and relatively complicated individually adjustable. The necessary set-up and changeover times for several film webs are still relatively high.

There are further known brake devices for winding B material of another kind. The US 4,350,310 discloses a device for braking running metal or plastic strips by means of a vacuum chamber for winding on a roll and the DE 601 816 relates to a method for winding and wrapping paper webs under a uniform, high tension by pulling the paper web over a surface and pressing it against by air pressure or negative pressure.

It is therefore an object of the present invention to shadow a simpler and improved gentle film web guide for flat embossing machines, which also allows optimal adjustment of the individual tensile stresses of several film webs, which facilitates the setup and retooling of several film webs and which also no contact with guide elements on the sensitive preshaped side (image side) of the film webs required.
This object is achieved according to the invention by a film web guide for a flat embossing printing machine according to claim 1.
The dependent claims relate to advantageous developments of the invention with further improvements of the film web guide and thus also the machine performance as well as with respect to the shortening of set-up and changeover times.

Fig. 1

schematisch eine erfindungsgemässe Folienbahnführung in einer Flachprägedruckmaschine mit flachen Brems- und Führungswänden als Folienspanneinrichtung,

Fig. 2a

im Querschnitt eine Brems- und Führungswand mit einer festen Trägerschicht mit Absaugöffnungen, einer luftdurchlässigen Auflageschicht, einer flachen Unterdruckkammer und einer Unterdruckquelle,

Fig. 2b

eine Trägerschicht mit Schlitzen in Längsrichtung,

Fig. 3

ein weiteres Beispiel einer Brems- und Führungswand im Längechnitt,

Fig. 4

eine Brems- und Führungswand mit luftundurchlässigen Abdeckungen unter den Folienbahnen,

Fig. 5

perspektivisch eine Einschubkassette für einen Vakuumschlaufenspeicher,

Fig. 6

im Grundriss eine Einschubkassette mit Seitenwänden und Abschlusswänden,

Fig. 7a, b

eine belüftete Umlenkstange mit Seitenführungselementen,

Fig. 8

einen Folienvorzug in Querrichtung, welcher aus der Längsrichtung umgelenkt ist,

Fig. 9

einen Folienvorzug in Längsrichtung, welcher aus der Querrichtung umgelenkt ist.

In the following the invention will be further explained by means of examples and figures, in which:

Fig. 1

1 schematically shows a film web guide according to the invention in a flat embossing printing press with flat braking and guide walls as film tensioning device,

Fig. 2a

a brake and guide wall in cross-section with a solid support layer with suction openings, an air-permeable support layer, a flat vacuum chamber and a vacuum source,

Fig. 2b

a carrier layer with slots in the longitudinal direction,

Fig. 3

another example of a braking and guiding wall in the length section,

Fig. 4

a braking and guiding wall with air-impermeable covers under the film webs,

Fig. 5

in perspective a slide-in cassette for a vacuum loop store,

Fig. 6

in outline a slide-in cassette with side walls and end walls,

Fig. 7a, b

a ventilated deflecting bar with side guiding elements,

Fig. 8

a film advantage in the transverse direction, which is deflected from the longitudinal direction,

Fig. 9

a film advantage in the longitudinal direction, which is deflected from the transverse direction.

Fig. 1 shows a film web guide 2 according to the invention for a flat embossing machine 1 with a flatbed press 4, wherein film webs 6 are fed from unwinding rollers 7 to a embossing table 3 for embossing flat material 5. The flat material 5 may consist of paper sheets or paper webs from rolls. The sheet is moved in the machine longitudinal direction X. In addition, film webs can also be drawn onto the embossing table 3 in the transverse direction Y ( Fig. 8 ). The film web guide 2 has a film tensioning device in front of the embossing table and film feed devices 9.1, 9.2 for a plurality of film webs 6.1, 6.2 after the embossing table 3. Between the unwinding rollers 7 and the embossing table 3, at least one flat braking and guide wall 10 is provided as a film tensioning device, over which the film webs 6 are guided. These brake and guide walls 10 have a solid support layer 11, which forms a support and guide surface, with suction openings 14 and a lying thereon, fixed to the support layer 11, cloth-like, air-permeable support layer 12 and an associated, adjustable negative pressure source 13, wherein a low pressure chamber 17, a negative pressure dp is generated. Thus, the film webs are easily pressed against the support layer and thus guided and braked adjustable. The flat brake and guide walls 10 may also be slightly bent and thus additionally result in a deflection of the film webs 6 (in Fig. 1 could eg the Brake and guide wall 10.1 have a slight bend in the direction of embossing point 3). The structure and operation of the brake and guide walls 10 are the Fig. 2-4 further explained.

Preferably, a braking and guide wall 10.1 is arranged directly in front of the embossing table 3 with which for each film web 6.1, 6.2 individually set an optimal tension for the embossing process, so that in particular all film webs 6 again solved properly after embossing of the embossed sheet 5 and can be dissipated. The required release stresses depend on the type and dimension of the film webs and the embossing process (different embossing surfaces and embossing, eg relief embossing).
Thanks to the space-saving, flat design of the inventive brake and guide walls 10.1 additional unwinding 7.3 can be mounted here for additional film webs 6.3 or even for simple smaller embossing orders (which do not require a film storage) directly in front of this braking and guide wall 10.1, which here particularly quickly and easily can be set up. Also, a film roll change is quickly possible by the new film web is simply glued to the brake and guide wall 10.1 to the old.

On the long path of the film web guide 2 from the unwinding rollers 7 to the embossing table 3, more than one braking and guiding wall 10 can be arranged. In the example of Fig. 1 is an additional brake and guide wall 10.2 mounted shortly after a film storage 20. The film storage are here as a vacuum loop storage, designed in particular as a horizontal vacuum double-loop memory 20 and in the film web feed, ie before the embossing table 3, arranged. By the vacuum loop memory 20, a first tensile stress Z1 is generated in the film webs 6.

For the brake and guide wall 10.2, a vacuum blower 21 of the loop memory 20 can be used here as a vacuum source 13. The negative pressure dp2 in a vacuum chamber 17 can be additionally adjusted, for example by means of a variable throttle point 19. The usually relatively moderate additional tensile stress Z2, which is generated by this braking and guide wall 10.2, is adjusted so that a properly stretched film web guide is achieved until the next brake and guide wall 10.1. The additional tensile stresses Z3 (see Fig. 4 ) on the brake and guide wall 10.1 can be adjusted individually for each film web 6.1, 6.2, 6.3 so that an optimal positioning of the embossment 3 and a proper detachment of the film webs 6 is achieved from the embossed sheet 5 after embossing.
In the example of Fig. 1 For example, the film web guide has a film removal device 29 after the film feed devices 9.1, 9.2 for the lateral removal of the distinct film webs 6.1, 6.2. This in turn free much space, which can be used for additional unwinding.
The adjustment of the braking forces or the tensile stresses in the film webs on the vacuum loop memory (Z1) and on the braking and guide walls (Z2, Z3) can be coordinated so that the detachment of the film webs from the embossed sheet 5 after embossing and the film web guide over the whole length is flawless and optimized.

At the embossing table 3 is here in the film webs a total tension
Z = Z1 + Z2 + Z3 generated. Due to the forced, precisely positioned and very rapid film preference by means of the film feed devices 9.1, 9.2, a tensile stress Z4 is generated, which must correspond to at least the total tensile stress Z. The stress of the pronounced film webs on the film feed devices 9 with deflection rollers, which must necessarily also touch the stamping page 6a of the film webs, is substantially higher than on the flat brake and guide walls 10, where no guide elements and no contact on the embossing page 6a are required. In the example of Fig. 1 the embossing page 6a is not contacted all the way from the unwinding rollers 7 to the embossing table 3.
The required negative pressure dp at the large-area brake and guide walls 10 is correspondingly relatively small and is for example 500 - 2000 Pa and the generated total tensile stress Z in the very thin film webs 6 is for example as possible less than 5 N / cm film web width.

For better film web guidance in particularly demanding embossing tasks (eg for relief embossing) with correspondingly high required tensile stress Z, the positioned film webs 6 on the embossing table 3 before embossing by briefly reversing the film feed devices 9 partially relaxed, then embossed and then pulled away again with full tensile stress Z. and thereby be detached from the embossed sheet 5 with high tension. For this purpose, the film feed devices 9 can be used e.g. drive backwards by 2 - 5 mm, thereby reducing the tension Z during stamping.

The Fig. 2a and 2b illustrate the structure and operation of the brake and guide wall 10th Fig. 2a shows in cross section a brake and guide wall 10 with a solid support layer 11 (which forms a support and guide surface) with suction openings 14 and a flat vacuum chamber 17, in which a negative pressure dp is generated by means of an adjustable vacuum source 13. On the support layer 11, a cloth-like, air-permeable support layer 12 is attached and fixed, for example clamped all around. The support layer is above all permeable to air in the tangential direction 18, so that the negative pressure dp is compensated under an overlying film web 6 or evenly distributed over the surface. The film webs are thus pressed uniformly and with relatively low contact pressure on the large-area support layer 12, thereby braked and uniform and constant in the preferred direction or direction of movement v Led film webs. The overlay layer 12 consists of a non-electrostatically chargeable soft material, so that no electrostatic frictional forces between the film web and the overlay layer can arise. For example, the overlay layer 12 may be made of natural fibers such as cotton (having minimal electrical conductivity) and formed as a nonwoven or fabric such as woven, knitted or knitted or felted and interstitially formed to provide a desired tangential air permeability (18) , With this overlay layer 12, a substantially constant coefficient of friction can be achieved, with static friction and sliding friction hardly differ.

The layer thicknesses of this overlay layer 12 may be e.g. 0.3-1 mm; depending on the nature and geometry of the wings and the overlay layer, their thickness may also be more, e.g. to 3 mm. This support layer can be easily replaceable attached to the carrier layer 11 and thus easily replaced to adapt to the nature of the film webs.

The Fig. 2b shows in plan an example of a preferably metallic carrier layer 11 with suction openings 14, which form an open surface portion of preferably 30 - 60% of the entire surface of the braking and guide wall 10 and which have an average diameter of eg 1 - 5 mm. The Fig. 2b shows an advantageous embodiment of the carrier layer 11 as a slot wall with slots which extend parallel to the preferred direction v of the film webs 6 and which allow a particularly good guidance. The slot width as well as the distance between the slots can be eg 1 - 3 mm and the slot length eg 10 - 30 mm. There are also other forms of suction openings 14 possible, for example, as a perforated plate with a small hole diameter, so that the film webs 6 run substantially flat over it.

Fig. 3 shows an example of a braking and guiding wall 10 in section along the film movement direction v with a length L which is at least 20 cm, preferably more, for example 30-50 cm. The Fig. 3 also illustrates the very flat design of the brake and guide walls 10 along the film web 6, which compared to previous clamping and guiding devices significantly less space is needed, which eg for additional unwinding (7.3 in Fig. 1 ) Creates space.

Fig. 4 shows an example of a braking and guiding wall 10 with three overlying film webs 6.1, 6.2, 6.3 and with airtight covers 15.1, 15.2 under a portion of the film webs, so that only the uncovered part L1, L2, L3 of length L is sucked and corresponding proportional braking forces or tensile stresses Z3.1, Z3.2, Z3.3 are generated in the film webs. In this example, with the cover 15.1 less, with 15.2 stronger and under the film web 6.3 not covered. The desired optimum braking force or tensile stress Zi can thus be set very easily for each film web individually and practically between 0 and 100%.

Between the film webs 6.1, 6.2, 6.3 also airtight covers 16 can be attached to here to avoid a pressure drop or a pressure loss and to set an optimal uniform distribution of the negative pressure dp at the brake and guide wall 10.
The air-impermeable covers 15 and 16 can for example be cut very easily from paper sheets and fixed to the front edge 10a of the brake and guide wall.

The brake and guide walls, ie the carrier layers 11 with the support layers 12, are preferably easily replaceable or insertable. So they can be easily removed, the covers 15, 16 on it new set and the layers 11 and 12 are used again without having to move the film webs or set up new. This is possible because on the brake and guide walls 10 no deflection rollers on the embossing page 6a of the film webs are present and needed.

The FIGS. 5 and 6 show examples of insertion cassettes 22 for vacuum loop storage 20, which in Fig. 1 are shown. Fig. 5 shows a perspective view and Fig. 6 in plan view a division with partitions and end walls of a slide-in cassette 22. A film web guide 2 with braking and guide walls 10 and combined with vacuum loops 20 allows a particularly good film web guidance and promotion. In order to further improve the film web guidance with optimum tensile stresses and to substantially shorten the set-up and changeover times, removable plug-in cassettes 22 can be used in the vacuum loop storages 20. On frame rods 25 here adjustable intermediate walls 23 are fixed so that the desired film webs are separated. The partitions 23 are closed at the bottom by end walls 24, which separated, not extracted chambers 26 are formed between and adjacent to the film webs 6.1, 6.2 in the film loop memory 20. Thus, on the one hand, a pressure loss between the film webs is avoided and on the other hand, a uniform, optimally adjustable suction force Z1 is exerted on the film webs in the vacuum loop memory. With these slide-in cassettes 22, the optimal adjustment and conversion of the intermediate walls can be performed very quickly without having to remove the film webs 6 (only the film loops are pulled out of the vacuum loop storage). The film webs do not need to be re-set up.

The inventive braking and guide walls 10 in flatbed embossing machines and the slide-in cassettes 22 in the vacuum loop memories 20 allow significantly shorter set-up and changeover times, improved Film web guidance, higher embossing performances and an extended range of embossing tasks. With ventilated deflection rods further improvements can be achieved.

The Fig. 7a, 7b show a deflecting element 27 for deflecting the film webs 6 in the form of a standing ventilated deflection bar 30, which generates an air cushion under the film webs 6, so that they are deflected with minimal friction. With side guide elements 32, the film web on the air cushion can be very accurately guided and stabilized. This results in comparison to previous deflection elements 27, for example in the form of roller axes, minimal frictional forces and better guidance of the film web. Advantageously, such ventilated deflection rods 30, as in Fig. 1 shown, for example, in front of a rear brake wall 10.1, before and after the embossing point 3, at the entrance of the vacuum loop memory 20 and also in the film preference in the transverse direction Y (see Fig. 8 ) may be arranged on the embossing point 3. In principle, all deflecting elements can be designed as ventilated deflection rods. The side guide elements 32 may be made, for example, as Aufsteckelemente (clips) from Delrin and simply plugged onto the standing deflection bar 30 and also moved and adjusted. The vented deflection rods 30 may consist, for example, of a tube vented with a slight overpressure with a microporous layer 31 which produces a finely distributed air cushion under the film web 6. This air cushion must be generated only in the deflection 34.

The inventive film web guide with braking and guide walls 10 and with ventilated deflection rods or air cushion axes 30 also makes it possible to redirect the film web guide by means of ventilated 90 ° deflection rods 33 from the machine direction X in the transverse direction Y or vice versa from the transverse direction Y in the longitudinal direction X, as in Fig. 8 and 9 is shown. Folienvorzüge with unwinding rollers depending in the longitudinal direction X and in the transverse direction Y are known and eg in the EP 0 858 888 described.

Fig. 8 shows an example with a film advantage 6y in the transverse direction Y with a braking wall 10y in the transverse direction Y and with ventilated deflection rods 30 with side guide elements 32 before and after the embossing point 3. This is particularly advantageous because the film web 6y after the embossing of the machine in the longitudinal direction X. moved flat material 5 must be removed transversely thereto and should not be moved. The unwinding roller 7 and the vacuum loop storage 20 here form a film advantage in the longitudinal direction X. By means of a ventilated 90 ° deflecting 33 but (individual) film webs 6 in the transverse direction Y (as film web 6y) are deflected (while other film webs 6 simultaneously in the longitudinal direction Embossing point 3 are continued). Thus, no additional unwinding rolls 7 and no vacuum loop stores 20 in the transverse direction are needed here. The 90 ° -Umlenkstangen 33 are arranged at an angle of 45 ° to the X and Y direction.

As in Fig. 9 conversely, film preferences in the transverse direction Y with unwinding rollers 7y and loop stores 20y in the transverse direction can also be deflected in the longitudinal direction X by means of a ventilated 90 ° deflection bar 33. Thus, a separate unwinding station with unwinding rollers 7y and loop memory 20y and braking walls 10y in the transverse direction next to the machine can be provided, which is not limited by the chain run of the machine. The example of Fig. 9 further shows a splicing device 35 which is arranged between the unwinding rolls 7 and the vacuum loop store 10 ( Fig. 1 ). With such a splicing station, a new film web can be attached or connected to an outgoing film web, for example by gluing, welding or bonding by means of adhesive tape.

The following terms are used in this description: 1 Flat embossing machine, flatbed embossing machine 2 Sheet guide 3 Embossing table, embossing point 4 Flatbed Press 5 flat material 6 film webs 6a Preprint page of 6 7 unwinding 9 Sheet feeder 10 Brake and guide wall 10a Leading edge of 10 11 Carrier layer, supporting and guiding surface 12 cloth-like, air-permeable coating layer 13 Vacuum source, suction fan 14 suction 15 Covers under 6 16 Covers between 6 17 flat vacuum chambers 18 tangential direction to 12 19 restriction 20 Vacuum loop storage, film storage 21 Vacuum source, suction fan 22 plug-in unit 23 partitions 24 end walls 25 frame bars 26 separated chambers 27 deflecting 29 Film takeaway 30 ventilated deflection rods, air cushion axles 31 microporous layer 32 Side guide elements (clips) 33 90 ° -Umlenkstange 34 deflection 35 splicing L Length of 10 L1, L2, L3 open part lengths Z Braking forces, tensile stresses dp Negative pressure in 10 v Preferred direction of 6 X Longitudinal direction, machine direction Y transversely

Claims (22)

1. A foil web installation (2) for a flat bed embossing machine (1) with foil webs (6), which from unwinding rolls (7) are conducted over an embossing table (3) with a foil tensioning device ahead of the embossing table and with foil feeding device (9) for several foil webs after the embossing table, characterised in that between the unwinding rolls (7) and the embossing table (3) at least one flat braking - and guiding wall (10) is provided as foil tensioning device, over which the foil webs (6) are conducted wherein a braking-and guiding wall (10.1) in advance direction (v) of the foil webs is provided directly ahead of the embossing table and which comprises a fixed supporting layer (11) with suction openings (14) and a cloth-like contacting layer (12) permeable to air, lying on the supporting layer (11) and attached to it an assigned, adjustable vacuum source (13) and wherein ventilated deflection bars (30) with or without lateral guiding elements (32) are provided.
2. A foil web installation according to claim 1, characterised in that additional unwinding rolls (7.3) in advance direction (v) of the foil webs are provided directly in front of the braking - and guiding wall (10.1) ahead of the embossing table.
3. A foil web installation according to claim 1, characterised in that more than one braking - and guiding wall is provided, wherein an additional braking - and guiding wall (10.2.) is arranged shortly after a foil store (20).
4. A foil web installation according to claim 1, characterised in that the length L of the braking - and guiding wall (10) amounts to at least 20 cm.
5. A foil web installation according to claim 1, characterised by a metallic supporting layer (11) with suction openings (14), which comprise an average diameter of 2 - 5 mm and a surface area proportion of the suction openings of 30 - 60 %.
6. A foil web installation according to claim 1, characterised in that the supporting layer (11) is designed as a slotted wall with slits in advance direction (v) of the foil webs and with a slit width of 1 - 3 mm.
7. A foil web installation according to claim 1, characterised in that the contacting layer (12) is designed to be not electro-statically chargeable and to be permeable for air in tangential direction (18).
8. A foil web installation according to claim 1, characterised in that the contacting layer (12) comprises a layer thickness of 0.3 - 3 mm and is fixed on the supporting layer (11) in a manner making it interchangeable.
9. A foil web installation according to claim 1, characterised in that on the braking - and guiding wall (10) coverings impermeable for air (15.1, 15.2) arc provided over a part of the length L underneath the foil webs (6.1, 6.2) for the individual adjustment of the braking forces (Z3.1, Z3.2) or that coverings impermeable for air (16) arc provided between the foil webs (6.1, 6.2, 6.3).
10. A foil web installation according to claim 1, characterised in that over the whole length of the foil web installation up to the embossing table (3) no guiding elements are present on the image layer side (6a) of the foil webs.
11. A foil web installation according to claim 1, characterised in that the braking - and guiding wall (10) is designed to be capable of being slipped-in or interchangeable.
12. A foil web installation according to claim 1, characterised by a vacuum loop store (20) ahead of the embossing table (3).
13. A foil web installation according to claim 12, characterised by a horizontal vacuum double loop store (20) and a braking - and guiding wall (10.2) located above it with a common suction fan (21).
14. A foil web installation according to claim 1, characterised by a vacuum loop store (20) with a removable slide-in cartridge (22) with adjustable partition walls (23) and lower end walls (24), which form chambers not under vacuum suction (26) between the foil webs (6.1, 6.2).
15. A foil web installation according to claim 1, characterised by a foil removal device (29) after the foil feeding devices (9) for the lateral taking away of the embossed foil webs (6.1, 6.2).
16. A foil web installation according to claim 12, characterised by braking forces and tensile stresses (Z1, Z2, Z3) in the foil webs (6) at the vacuum loop store (Z1) and at the braking - and guiding walls (Z2, Z3) arc adjustable and matchable to one another by means of adjustable vacuum sources (13) at the braking- and guiding walls (10) and by a vacuum fan (21) at the vacuum loop store (20).
17. A foil web installation according to claim 1, characterised in that in addition a foil advance (6y) in transverse direction (Y) with a braking - and guiding wall (10y) in transverse direction is provided.
18. A foil web installation according to claim 1, characterised in that a foil advance (6y) in transverse direction (Y) with a vacuum loop store (20y) in transverse direction is provided.
19. A foil web installation according to claim 1, characterised by a foil advance (6y) in transverse direction (Y), which is deflected to the longitudinal direction (X) by a ventilated 90° - deflection bar (33).
20. A foil web installation according to claim 1, characterised by a foil advance (6) with a vacuum loop store (20) in longitudinal direction (X), which by means of a ventilated 90° - deflection bar (33) is deflected to the transverse direction (Y).
21. A foil web installation according to claim 1, characterised in that between the unwinding rolls (7) and a vacuum loop store (20) a splicing device (35) is provided.
22. A flat bed embossing machine with a foil web installation (2) and with at least one braking - and guiding wall (10) according to one of the preceding claims.

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