EP3553001B1 - Prevention of the flutter of the adhesive flag in foil printing - Google Patents

Description

The invention relates to a method for avoiding the sticking out, hanging down and fluttering of an adhesive flag after a roll change in a reel printing machine in order to avoid damage to both the adhesive flag and thus also the web-like printing material and components of the corresponding printing machine. The invention also relates to a device for carrying out this method.

In the case of web printing machines, the substrate is printed as a web in the printing machine and also processed in a variety of different variants. The printing material is fed to the web-fed printing machine in such a way that the web-like printing material is unwound from a roll of the printing material. For this purpose, the roll is clamped in a device in which the roll is unwound and the unwound printing substrate web is fed to the subsequent components of the web printing machine. As devices for receiving a printing material roll, unwinders, unwinders, roll stands or roll changers in various designs are known from the prior art, the technical definitions and the technical differences between the various designations being fluid and may vary. For all these different terms unwinder, unwinder, roll stand or roll changer, only the term roll changer is used below.

The method according to the invention also applies to other processing processes and processing machines in which a web-shaped fluid-repellent material is processed in a different manner without necessarily being printed, such as for cutting open webs, wrapping the rolls, etc.

Since only a limited amount of a web can be unwound from a roll, it is necessary for an uninterrupted production process that the web running off the so-called old roll is glued to a new web of a so-called new roll. For this purpose, the beginning of the web of the new roll, which has been prepared and provided with an adhesive strip, is pressed against the running web of the old roll, so that the web of the new roll is glued to the web running off the old roll. After the gluing process, the running web of the old roll is cut, so that after the gluing process, the web of printing material is only unwound from the new roll.

The web of the new roll can be glued to the running web of the old roll either with the web standing still at least in the roll changer area or this takes place fully automatically while the web is running, whereby this is preferably possible at the maximum possible production speed.

Since there is a time difference between sticking the web to the new roll and cutting through the web, especially at correspondingly high web speeds, an adhesive flag is created as part of the web of the old roll, which is connected to the web of the new roll by means of the glue point. The adhesive lugs usually have a length of approx. 10 to approx. 60 centimeters.

Since these adhesive tabs are only connected to the adhesive point with the web of the new roll at their leading end, seen in the web running direction, they can hang down, for example, provided the adhesive tab is arranged on the underside of the web or the adhesive tab can be wrapped around rollers etc. at least partially detach from the web, in particular with the trailing edge. This makes it possible that either the web is damaged by the mechanical resistance when the adhesive flag strikes a component of the printing machine and can tear, or components of the printing machine which are arranged in the area of the web can be damaged.

In particular, when film-like printing materials, such as plastic films, metal foils or other comparable materials with relatively high mechanical tear resistance, are processed, there is a considerable risk of production interruption due to a web break or damage to machine components.

From the DE 44 41 447 C1 a solution is known with which such freely hanging or peeling adhesive strips can be reduced at least in their effective length by not only attaching an adhesive strip to the web for the formation of the glue point as a connection between the web of the old roll and the web of the new roll , but by applying an additional adhesive in the area after the glue point.

However, since the length of the adhesive flag varies for various reasons in practice - this is dependent, for example, on the web speed during the gluing process, the position of the reflective marks to the gluing point, the reaction speed of the gluing and knocking off device - the DE 44 41 447 C1 known solution, the maximum length of the adhesive flag can be limited, because the adhesive application must in no case go beyond the area of the adhesive flag in order to avoid web winders, web breaks, damage or soiling of components of the printing machine, etc. If a corresponding, applied adhesive is not covered by the adhesive flag, it adheres to the component such as a deflection roller, pull roller, pressure roller or a pressure cylinder and leads to considerable impairments such as winders, stoppers, web tears by sticking together with the web as well as impurities.

WO 93/25460 A1 and WO 2015/173275 A1 reveal more roll changers.

The invention is therefore based on the object of creating a solution which makes it possible to allow the adhesive flag to adhere over its entire length, in particular to a web with high mechanical strength.

The object is achieved according to the invention in that when a fluid-repellent substrate is used, an adhesive-free liquid is applied to the new roll and / or to the side of the adhesive flag facing the web at least in a partial area of the adhesive tab.

Such an implementation of the method has the advantage that the adhesive flag can be fixed in its entire length on the running web, since the adhesive-free and thus basically non-adhesive web running off the new roll is on the adhesive flag and / or on the web Liquid can also be applied to the web in areas that are no longer covered by the adhesive flag, since the web exposed to the liquid, if it comes into contact with other components of the printing machine, normally does not have any problems, web breaks, winders or other production problems caused. Even if one or both sides of the web are printed with the offset printing process, the application of the liquid beyond the area of the adhesive flag does not lead to production disruptions. Even in spite of the process-related fluctuation in the length of the adhesive flag, it is thus possible to reliably ensure that the adhesive flag is fixed over its entire extent.

In an advantageous embodiment of the invention, water or an aqueous solution is used as the liquid. In the case of the aqueous solution, additives are added to the water, for example surfactants, in order, for example, to reduce the surface tension of the liquid.

In a further advantageous embodiment, a liquid based on hydrocarbons is used, such as, for example, low-viscosity oils, oils of medium to high viscosity or solvent-like substances. The wettability is also ensured here. Liquids based on hydrocarbons are particularly advantageous when, for example, printing processes are used in which water or an aqueous solution on the substrate would impair the printing process.

In a further advantageous embodiment, an emulsion of water or an aqueous solution and a liquid of hydrocarbon can also be used as the liquid. Such combinations enable optimal adaptation of the wettability and the capillarity of the liquid to the substrate and, if necessary, to the processing and / or printing process with regard to the compatibility with the liquid.

In a particularly advantageous embodiment of the invention, the liquid is applied at least over the entire surface of the adhesive flag. The application can either be made on the adhesive surface or on the web running off the new roller.

The application of the liquid, if the liquid is applied to the web, can also take place in an area which is no longer covered by the same even with the maximum length of the adhesive flag. This ensures that regardless of the actual length of the adhesive flag, even with the maximum length of the adhesive flag, it adheres to the web over the entire surface and has no protruding edges or areas.

Fig. 1

eine schematische Darstellung einer Druckmaschine gemäß dem Stand der Technik

Fig. 2

eine schematische Darstellung einer Druckmaschine unmittelbar vor dem Rollenwechsel gemäß dem Stand der Technik

Fig. 3

eine schematische Darstellung einer Druckmaschine unmittelbar nach einem Rollenwechsel gemäß dem Stand der Technik

Fig. 4

eine schematische Darstellung einer Druckmaschine mit dem erfindungsgemäßen Rollenwechsler unmittelbar vor dem Rollenwechsel

Fig. 5

eine schematische Darstellung einer Druckmaschine mit dem erfindungsgemäßen Rollenwechsler unmittelbar nach dem Rollenwechsel

Preferred developments of the invention emerge from the subclaims and the following description. Various exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being restricted thereto. It shows:

Fig. 1

a schematic representation of a printing press according to the prior art

Fig. 2

a schematic representation of a printing press immediately before the roll change according to the prior art

Fig. 3

a schematic representation of a printing press immediately after a roll change according to the prior art

Fig. 4

a schematic representation of a printing press with the roll changer according to the invention immediately before the roll change

Fig. 5

a schematic representation of a printing press with the roll changer according to the invention immediately after the roll change

Fig. 1 shows the schematic structure of a web printing machine 1, in which the web-shaped substrate in the roll changer 2 is unwound from a rotating old roll 7. The old roll 7 is mounted in mandrels (not shown) and is either driven or driven and braked when the web 5 is unwound, only braked or simply dragged to build up web tension. Fig. 1 shows a schematic diagram of a roll changer 2, as it is usually used in so-called flying roll changes, but the invention is also possible with so-called idle roll changers or unwinders.

The unwound web 5 is usually also guided over various web guiding elements such as deflection rollers 9, in this case the web 5 can alternatively be aligned transversely to the web running direction 6. It is also possible to bring driven deflection rollers 6 or draw rollers (not shown in the drawing) into contact with the web 5 in order to be able to influence the web tension in the region of the roll changer 2.

The web 5 unwound from the old roll 7 is - after passing through the remaining part of the roll changer 2 viewed in the web running direction 6 - fed to the following components of the processing machine. In the example of a web printing machine 1 shown, this is usually at least one printing device with which the web 5 is printed on at least one side, for example in offset, gravure, flexographic or digital printing processes.

The web 5 thus printed at least on one side and at least in one color is fed to a post-processing unit 4. This can basically be a cross-cutting device or a folding device, in the case of printing or processing foils or foil-like substrates such as plastic foils, metal foils or laminates, for example in packaging printing, rewinders are used here, for example.

Since the old roll 7 can only have a limited amount of the web-shaped substrate, a new roll 8 is introduced into the roll changer 2 - mostly during production - to ensure a more or less uninterrupted production, which is provided with a double-sided adhesive tape for adhesive preparation before or after the roll change is provided.

The in Fig. 1 The roll changer 2 shown as an example can accommodate two rolls on its support arm 11, but roll changers 2 with more than two absorbable rolls are also known. The number of rolls and the arrangement of the old roll 7 as well as the new roll 8 is irrelevant for the present invention and therefore does not represent a restriction.

Fig. 2 represents the web printing machine 1 according to FIG Fig. 1 represents, but at a point in time at which the old roll 7 approaches its minimum diameter. The support arm 11 pivots about a horizontal axis so that the new roll 8 is brought into a position in which the new roll 8, which has been prepared for adhesive and accelerated to the web speed, can be brought into contact with the web 5 running off the old roll 7. Here, the so-called adhesive head 10, which comprises a pressure roller and a cut-off knife, is brought into the immediate vicinity of the web 5 running off the old roll 7.

Even if Fig. 2 represents the situation immediately before a roll change using a flying roll changer 2 or autopasters, the present invention can also be transferred to other types of roll changers 2 not shown in the drawing, such as standstill roll changers.

If the old roll 7 reaches a predetermined adhesive diameter and the new roll 8 has the circumferential speed exactly identical to the web speed, a pressure roller or pressure brush, for example, presses the web 5 running off the old roll 7 onto the new roll 8, so that the double-sided adhesive tape causes the roll from the old roll 7 running web 5 is connected to the web 5 of the new roll 8 by means of an adhesive connection, immediately thereafter the cutting knife of the adhesive head 10 cuts through the web 5 running off the old roll 7.

Fig. 3 shows symbolically the web-fed printing machine 1 immediately after the roll change has been carried out, the web 5 being unwound from the new roll 8 and being fed to the components of the printing machine 1.

As in Fig. 3 As can be seen, the severing of the web 5 running off the old roll 7, albeit only for a very short time after the web 5 was glued to the new roll 8, results in an adhesive flag 12, which is only connected to the web 5 at the glue point 13 and is therefore no longer connected to the web 5 over its extension in the web running direction 6, which represents the length of the adhesive flag 12.

The resulting adhesive flag 12, which is actually the remainder of the web 5 running off the old roll 7 from the adhesive point 13, can therefore either hang down due to gravity, so that due to its length of approx. 20 to approx. 500 mm with components of the Printing machine 1 can come into contact, or comes.

It is also possible that the adhesive flag 12 is in contact with the web 5 or lies on the web 5 at higher web speeds, provided that the adhesive flag 12 is attached to the upper side of the web, but with either very stiff substrates or when the web 5 is deflected, for example on deflection rollers 9, the adhesive flag 12 can or will protrude from the web 5.

If this adhesive flag 12 comes into contact with components or parts of the printing press 1, either parts of the adhesive flag 12 can tear off and form snippets that can cause production disruptions, or the web 5 can tear or completely tear.

In particular in the case of substrates with high mechanical strength, such as plastic films or laminates, it is also possible that components or parts of the printing press 1 are affected by a protruding adhesive tab 12.

Although devices for separating such adhesive lugs 12 are known from the prior art, they fail to function if the web speeds are not too high and in particular in the case of substrates with high mechanical strength.

Fig. 4 shows a printing press 1 with a roll changer 2 for carrying out the method according to the invention. This optionally comprises one or more application devices 14 for applying adhesive-free liquid to the new roller 8 and / or to the side of the adhesive flag 12 facing the web 5.

In a method for carrying out the roll change according to the invention, at the point in time when the web 5 of a substrate to be processed running from the old roll 7 is pressed against the adhesive 13 - for example in the form of an essentially double-sided adhesive tape - or depending on the web speed a few seconds to a few hundredths of a second before the web 5 is pressed against the new roll 8, or against the web 5 wound onto the new roll 8, to form an adhesive connection between the web 5 running off the old roll 7 and the new roll 8, or the one on the New roll 8 wound web 5 and the subsequent severing of the web 5 running off the old roll 7, with the severing of the web 5 unwound from the old roll 7 mostly a Adhesive flag 12 with an extension from the glue point 13 to the cut edge at the glue point 13 remains, at least on or in a partial area of the glue flag 12, an adhesive-free liquid is applied to the new roll 8 and / or on the side of the glue flag 12 facing the web 5.

The preferably thinly applied film of the adhesive-free liquid wets the surface of the web 5 and / or the resulting adhesive flag 12 in the case of the use of a fluid-repellent and thus not the liquid-absorbing substrate such as plastic films, metal foils, laminates with cover layers of fluid-repellent material such as with plastic or metal foil laminated webs (5) made of non-absorbent or absorbent material or, for example, impregnated substrates made of non-absorbent or generally absorbent material, and when the adhesive flag 12 is placed on the corresponding side of the web - in particular after the adhesive flag 12 has been pressed on - for example no longer escape by rotating a guide roller 9. Due to the capillarity, the liquid is held in the very thin gap between the web 5 and the adhesive tab 12 or is evenly distributed there, so that especially when the web 5 is pulled out or compressed in the area of the adhesive tab 12, for example after passing through a deflection roller 9 or a pair of rollers placed next to one another, a full-surface liquid film remains at least in the areas of the liquid application.

As a result of the capillary effect and the van der Waals forces of the liquid used, albeit adhesive-free, the adhesive tab 12 adheres to the web 5 with relatively strong adhesion as long as a liquid film is present. If this liquid film dries off or if the liquid diverges out of the substrate or into the substrate, this usually takes considerably longer than the passage time of a dot through a corresponding printing machine 1 - such a passage time is only a few seconds, depending on the machine configuration and the web speed - so the adhesive flag 12 is no longer fixed to the web 5.

Fig. 5 shows the web printing machine 1 immediately after the roll change and the application of the liquid according to the invention to at least a partial surface of the adhesive flag 12, so that the adhesive flag 12 on the web 5 by the van der Waals forces between the web 5 and the liquid on the one hand and between the liquid and the adhesive tab 12 on the other hand adheres.

An adhesive flag 12 fixed to the web 5 in this way can be guided through the printing press 1 with the web 5 without impairing production, damaging the web 5 or damaging parts or components of the printing press 1.

Due to the low holding force in the form of the van der Waals force of the liquid on the web 5, in contrast to adhesives or liquids containing adhesives, there is no impairment of production due to web breaks, winders or contamination of web guiding elements when the liquid is applied to the web 5 in an area which is larger than the area which is covered by the adhesive flag 12 lying on the web 5.

If, for example, the liquid is applied to the web 5 in an area of the extension x seen in the web running direction 6, the liquid is not completely covered by the adhesive flag 12. If this area of the web 5 comes into contact with a web-guiding component, such as a deflection roller 9 or a printing cylinder, the web-guiding component is indeed wetted with the liquid, but due to the basically non-adhesive effect of the adhesive-free liquid, this does not impair production such as web tears, winders or soiling with adhesives that are mostly difficult to remove.

The liquid is thus advantageously applied at least over the entire surface of the adhesive flag 12. The application can take place either on the adhesive surface or on the web 5 running off the new roller 8. However, it is also possible to apply the liquid in an area which is spaced apart from the adhesive point 13, i.e. the liquid is only applied in the rear area of the adhesive flag 12 as seen in the direction of web travel 6.

The liquid can also be applied over the entire width of the web or interrupted, for example in at least one strip parallel to the web running direction 6 or punctually, that is also interrupted in the extension of the web running direction.

Water or an aqueous solution can be used as the liquid. In the case of the aqueous solution, additives are added to the water, for example surfactants, in order, for example, to reduce the surface tension of the liquid.

However, a liquid based on hydrocarbons, such as, for example, low-viscosity oils, oils with medium or high viscosity or solvent-like or solvent-containing substances can also be used as the liquid. The wettability is also ensured here. Liquids based on hydrocarbons are particularly advantageous when, for example, printing processes are used in which water or an aqueous solution on the substrate would impair the printing process.

An emulsion composed of water or an aqueous solution and a liquid composed of hydrocarbon can also be used for application to the web 5 and / or to the adhesive lug 12. Such combinations enable optimal adaptation of the wettability and the capillarity of the liquid to the substrate and, if necessary, to the processing and / or printing process with regard to the compatibility with the liquid.

As already mentioned above, the liquid can be applied to the web 5 running off the old roll 7 and / or to the web 5 wound onto the new roll 8 immediately before the roll change, both when the web 5 is stationary and when the web 5 is moving. In the case of the application of liquid to a stationary web 5, this can take place either in the case of a standstill changer with the web 5 standing within the reel changer 2, while the production takes place by removing the web 5 from a paper store.

However, it is also possible, which is especially the case with technically simple reel changers 2 or unwinders, that the printing press 1 has to be stopped in order to glue the web 5 from the old roll 7 to the new roll 8, so that a stationary web 5 results results, so that the liquid can be applied either manually, for example by means of a spray bottle, preferably with an atomizer, by means of a sponge or cloth or by means of an application device 14 to the web 5 and / or to the new roll 8 in a limited time window before the roll change.

In the case of highly automated reel changers 2 with automatic reel change, the liquid is applied either to the web 5 running off the old reel 7 or to the new reel 8 at the appropriate web speed, so that the liquid is applied - especially to the new reel 8 - immediately before the reel change must take place and is essentially only possible by means of an application device 14 built into the roll changer 2.

Such an application device 14 can either be designed as a device designed with a liquid reservoir, such as a liquid-storing filling, such as a moistened cloth or a sponge, which is set on the new roller 8 and / or on the running web 5 in a correspondingly timed manner. However, it is also possible to design the application device 14 as a spray device with at least one spray nozzle which traverses over the substrate in the extension of the web or roll width, or as a spray tube to design at least one spray nozzle across the width of the processing web 5. In the case of a spray tube extending over the entire width of the web, the timing of one or more corresponding valves can be used to control the application of liquid very precisely in terms of time, and thus both the position and the length of the application of liquid can be controlled.

Such application devices 14 can of course also be used in standstill roll changers or so-called unwinders for manually gluing the web 5 from the old roll 7 to the new roll 8 in order to carry out the liquid application uniformly, reproducibly and automatically or partially.

Regardless of the type of liquid application, it is advantageous if, after the liquid has been applied, the adhesive flag 12 is pressed against the web 5 running off the new roll 8 by means of a pressing device, which is achieved, for example, by means of a deflection roll, a web guide roll or a pull roll with an employed pressure roller hired pull roller pair or a hired pair of printing cylinders can be done.

List of reference symbols

1

Printing press

2

Reel changer

3

Pressure unit

4th

Post-processing

5

train

6th

Direction of web travel

7th

Old roll

8th

New role

9

Deflection roller

10

Glue head

11

Beam

12th

Sticky flag

13th

Splice

14th

Application device

X

Extension of the liquid application

Claims (11)

1. A method for carrying out a roll change, wherein a web (5), which runs off an old roll (7), of a substrate to be processed is pressed against a new roll (8), which is provided with an adhesive point, of the substrate to be printed, wherein the web (5), which runs off the old roll (7), which runs off, is severed at a cutting edge after pressing against the adhesive point of the new roll (8) and after forming an adhesive bond between web (5), which runs off, and new roll (8), wherein at least one tail (12) with an extension from the adhesive point (13) to the cutting edge remains mostly on the adhesive point (13), characterized in that, when using a fluid-repellent substrate, an adhesive-free liquid is applied to the new roll (8) and/or to the side of the tail (12) facing the web (5), at least in a partial surface of the tail (12).
2. The method according to claim 1, characterized in that water or an aqueous solution is used as liquid.
3. The method according to claim 1, characterized in that a hydrocarbon-based liquid is used.
4. The method according to one of claims 2 or 3, characterized in that an emulsion of water or an aqueous solution and a liquid of hydrocarbon is used as liquid.
5. The method according to one of claims 1 to 4, characterized in that the liquid is applied at least across the entire surface of the tail (12).
6. The method according to one of claims 1 to 5, characterized in that the liquid is applied when the web (5) is stationary.
7. The method according to one of claims 1 to 5, characterized in that the liquid is applied when the web (5) moves.
8. The method according to one of claims 1 to 7, characterized in that the liquid is applied by means of a sprayer comprising at least one spray nozzle.
9. The method according to one of claims 1 to 8, characterized in that the liquid is applied by means of a strip comprising liquid-storing border.
10. The method according to one of claims 1 to 7, characterized in that the tail (12) is pressed against the web (5), which runs off the new roll (8), by means of a pressing device after the application of the liquid.
11. A roll changer (2) for carrying out a roll change, wherein a web (5), which runs off an old roll (7), which runs off, of a substrate to be processed is pressed against a new roll (8), which is provided with an adhesive point, of the substrate to be printed, wherein the web (5), which runs off the old roll (7), which runs off, can be severed at a cutting edge after pressing against the adhesive point of the new roll (8) and after forming an adhesive bond between web (5), which runs off, and new roll (8), wherein at least one tail (12) with an extension from the adhesive point (13) to the cutting edge remains mostly on the adhesive point (13), characterized in that the roll changer (2) comprises an application device (14), via which an adhesive-free liquid can be applied to the new roll (8) and/or to the side of the tail (12) facing the web (5), at least in a partial surface of the tail (12), when using a fluid-repellent substrate.

Images