CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit and priority of European Patent Application No. EP 201960457, filed Sep. 14, 2020. The entire disclosure of the application referenced above is incorporated herein by reference.

FIELD

The disclosure relates to a device for embossing foils, including a base embossing plate and a counter embossing plate, the surfaces of which facing one another are respectively at least partially planar and which, for embossing a foil lying between them, are arranged so as to be movable on the one hand towards one another and on the other hand away from one another in parallel alignment of their at least partially planar surfaces, wherein the base embossing plate is provided on its side facing the counter embossing plate with a plurality of embossing inserts for embossing a plurality of blanks to be punched out of the foil and wherein the embossing inserts are configured and arranged in such a way that, during embossing of the foil, they respectively cooperate with a corresponding embossing area arranged on the side of the counter embossing plate facing the base embossing plate.

BACKGROUND

When we talk about embossing a foil, this also refers to the deformation of foils in general. In this context, smooth foils can be embossed or deformed, but also already pre-embossed or pre-deformed foils.

Foils in the packaging sector, also known as blanks, typically have a thickness between 10 and 150 μm and can be provided with a wide variety of embossings. These embossings can be carried out over the entire surface, partially or as edge embossing. The reason for these embossings is typically to ensure the separation of the foils when they are provided for their application to e.g. a container in the form of a foil stack, as explained below.

Such foils, also called sealing foils, are used in the packaging industry for a variety of different products, for example as closure for corresponding packaging containers, such as cups or boxes. Here, the sealing foils are often obtained by punching out corresponding shapes from a strip-shaped material. The material used here can be, for example, aluminum foil, plastic foil or composite materials made of plastic and aluminum. The material is often printed on at least one or both sides. In order to close packaging containers, the sealing foils are typically glued or welded onto the containers. For this purpose, the foils can be provided with a layer of heat-sealing lacquer on the side facing the packaging container, for example.

After punching out a shape corresponding to the opening of the packaging container to be closed from a web material, the obtained shaped pieces are usually stacked. In order to close the packaging container, the shaped pieces, which are intended for example as lids, are removed from the stack with suitable gripping systems, such as vacuum grippers, and arranged on the opening of the packaging container to be closed. Depending on the application system used, such as by means of heat-sealing lacquer, the shaped pieces provided as lids are then bonded to the packaging container under the action of pressure and/or heat. In order to prevent that several shaped pieces adhere to each other when the shaped pieces are lifted from the stack, it is known from the state of the art to provide the shaped pieces with an embossing in the edge region, which prevents the individual shaped pieces from adhering to each other. It is also known that embossings are partially omitted in order to achieve better readability by barcode scanners. In order to carry out these various embossings, processes using engraved rollers or embossing plates are known. These embossings can also be carried out in a controlled manner via tactile marks to the printed image.

A frequently occurring problem is that the foils to be embossed can have differences in material thickness of up to 5 μm over the embossing width. As a rule, 2 to 18 blanks to be punched out are arranged over the embossing width. Therefore, in many cases different embossing depths for the different punched blanks are present. This has negative effects on the destackability as well as the stability of a stack of blanks produced in this way. If, for example, the embossing depth of the individual blanks varies considerably in the case of pure edge embossing, a stable stack of blanks cannot be formed, which can lead to considerable problems at the filling line—targeted removal is often not possible in this case.

SUMMARY

Based on this, it is the object of the disclosure to provide a device for embossing thin-walled foils that comes closer to the goal of ensuring an embossing depth that is independent of the material thickness of the foil.

Thus, according to the disclosure, a device for embossing foils is provided, including a base embossing plate and a counter embossing plate, the surfaces of which facing one another are respectively at least partially planar and which, for embossing a foil lying between them, are arranged so as to be on the one hand movable towards one another and on the other hand away from one another in parallel alignment of their at least partially planar surfaces, wherein the base embossing plate is provided on its side facing the counter embossing plate with a plurality of embossing inserts for embossing a plurality of blanks to be punched out of the foil, and wherein the embossing inserts are configured and arranged in such a way that, during embossing of the foil, they respectively cooperate with a corresponding embossing area arranged on the side of the counter embossing plate facing the base embossing plate, characterised in that each embossing insert is held on the base embossing plate by means of an own embossing insert retainer so as to be movable by a predetermined amount relative to the base embossing plate in the direction perpendicular to the at least partially plane surface of the base embossing plate, is at the same time spring-borne relative to the base embossing plate by means of an own embossing insert suspension and is guided by means of an own embossing insert guide during the spring-borne movement relative to the base embossing plate enabled thereby.

It is thus an essential aspect of the disclosure that a device for embossing foils, which is otherwise constructed in a conventional manner, is provided on its base embossing plate with such embossing inserts, which each have an own embossing insert retainer, an own embossing insert suspension and an own embossing insert guide. The fact that each embossing insert is provided with an own embossing insert retainer, an own embossing insert suspension and an own embossing insert guide means that for each embossing insert separately such devices are provided which only cooperate with this embossing insert and with no other. In this way, the disclosure enables the movement of each embossing insert during embossing of the foil to be independent of the movements of the other embossing inserts. In particular, this allows the embossing inserts to behave in such a way that they “react” independently of each other to different foil thicknesses so that, despite the different thicknesses, essentially the same embossing depth is obtained. If the foil to be embossed has differences in its material thickness over its surface, this can be compensated for by the separate bearing, suspension and guidance of the individual embossing inserts. Fluctuations in the foil thickness, which would otherwise have led to different embossing depths, can thus be compensated. In the best case, practically the same embossing depth can be achieved with each embossing insert.

Here, the embossing insert retainer ensures the basic fastening of the embossing insert to the base embossing plate. This fastening is such that the embossing insert is basically movable relative to the base embossing plate, namely a movement in the normal direction to the at least partially planar surface of the base embossing plate is possible. This corresponds to a movement of an embossing insert relative to the base embossing plate in a direction parallel or anti-parallel to the direction in which the base embossing plate and the counter embossing plate are moved towards each other for embossing the foil. This means that each embossing insert during embossing, namely when the foil is compressed between a respective embossing insert and a corresponding embossing area on the counter embossing plate, a certain “yielding” of the respective embossing insert towards the base embossing plate is made possible. This retracting or yielding of the respective embossing insert takes place in a controlled manner due to the embossing insert suspension associated with the respective embossing insert in combination with the respective embossing insert guide, so that even in the case of different material thicknesses across the surface of the foil to be embossed, differences in the embossing depths for the different embossing inserts can be reduced or completely avoided.

For this purpose, the embossing insert retainers can be designed in different ways. However, according to a preferred further development of the disclosure it is provided that the embossing insert retainers each comprise a damping device for damping the possible movement of the respective embossing insert relative to the base embossing plate. Such a damping device thus offers a certain resistance to the movement of the respective embossing insert, which makes the movement of the embossing insert relative to the base embossing plate more controllable.

To this end, different damping devices may be provided. However, according to a preferred further development of the disclosure, the damping device respectively comprises a spring bolt and/or a damping disc. Here, it is particularly preferred that the embossing inserts are respectively held on the base embossing plate by means of a fastening means, wherein the fastening means is passed through the damping device. If, for example, in connection with this preferred embodiment of the disclosure, a spring bolt is provided in combination with a damping disc as a damping device, a screw is preferably passed through these components by means of which the respective embossing insert is fixed to the base embossing plate.

Different designs are possible for the embossing insert guides, too. According to a preferred further development of the disclosure, the embossing insert guides respectively comprise a column guided in a bush. In this case, moreover, it is preferably provided, that the column of a respective embossing insert guide is fixed in the respective embossing insert and the bushing is fixed in the basic embossing plate.

With regard to the embossing insert suspensions it is essential that these ensure a certain spring-borne mounting of the embossing inserts with respect to the base embossing plate. For this purpose, a respective embossing insert suspension is preferably designed in such a way that it comprises an elastic element attached to the respective embossing insert. Moreover, according to a preferred further development of the disclosure it is provided that each embossing insert is provided with a plurality of embossing insert guides and/or with a plurality of embossing insert suspensions. Furthermore, according to a preferred further development of the disclosure, the shape of the embossing inserts is substantially round, wherein the embossing insert retainer is arranged centrally in each embossing insert. In this way, a particularly stable support and guidance of the embossing inserts at the base embossing plate is ensured.

The device for embossing foils according to the disclosure can also be designed differently with regard to the transport of the foil to be embossed and the arrangement of the embossing inserts. However, according to a preferred further development of the disclosure, it applies that it comprises a transport device by means of which the foil to be embossed is movable in a transport direction relative to the base embossing plate, wherein at least a part of the plurality of embossing inserts are arranged side by side in a direction perpendicular to the transport direction. In other words, according to this preferred further development of the disclosure it is further provided, that at least some of the embossing inserts are arranged in the width perpendicular to the working direction given by the transport direction of the foil. According to a preferred further development of the disclosure it is further provided, that the embossing inserts, which are arranged side by side in a direction perpendicular to the transport direction, are at least partially arranged offset to each other in the transport direction. Such an offset arrangement makes it possible to arrange a greatest possible number of embossing inserts on the area given by the base embossing plate, in the case of essentially round embossing inserts, for example, in the form of a practically hexagonal arrangement of the embossing inserts relative to one another, which leads to practically optimum utilization of the available area.

Regarding the embossing areas in the counter plate corresponding to the embossing inserts provided in the base embossing plate, these can basically be designed in a conventional manner. According to a preferred further development of the disclosure, it is provided in this context, that the embossing areas corresponding to the embossing inserts provided in the base embossing plate are designed as inserts that are detachably fixed in the counter plate. In particular, the embossing areas designed as such inserts can be screwed into the counter plate. In accordance with a preferred further development of the disclosure, it is provided, that the inserts are mounted in the counterplate in an unsprung manner, preferably screwed into the counterplate in an unsprung manner.

In the following, the disclosure will be further explained in detail by means of a preferred exemplary embodiment with reference to the drawings.

