Technical field

The invention relates to a sealing device and a method for heat sealing packaging material for producing sealed packages. The invention also relates to a filling machine.

Background art

In filling machines for liquid food packages, such as e.g. sold by Tetra Pak under the name Tetra Pak A1 , a web of packaging material is sterilized, and is subsequently formed into a tube by making the longitudinal edges of the web overlap each other and sealing the overlap area. This tube is filled with liquid food continually, and the tube of packaging material is transversally sealed and cut such that separate packages with liquid food are formed.

The transversally seal procedure is typically carried out by a sealing device. The sealing device often comprises a first and a second jaw, wherein the portion of the tube subject to receive a transversal seal is arranged in between the first jaw and the second jaw during the formation of the seal. The first jaw is arranged to provide means for allowing the sealing device to press the packaging material of the tube during the formation of the seal, and the second jaw is arranged to provide sufficient heat to the packaging material of the tube needed for the formation of the seal.

In order for the first jaw to provide means enabling a sufficient applied pressure to the tube, an external force must be supplied to the first jaw. The problem with the prior art solutions is that the force application will result in pull forces in different parts of the transport system, resulting in the jaws of the sealing device experiencing tension, thus increasing the risk of

mechanical failure. Summary of the invention

It is an object of the present invention to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solve at least the above mentioned problem.

According to a first aspect, these and other objects are achieved in full, or at least in part, by a sealing device for heat sealing packaging material for producing sealed packages. The sealing device comprises a first jaw comprising an electromagnet, and a second jaw comprising a magnetic element. The second jaw is arranged opposite to the first jaw to form a gap adapted to receive the packaging material, such that the first jaw and the second jaw are attracted to each other upon actuation of the electromagnet to close the gap and clamp the packaging material between the first jaw and the second jaw.

This is advantageous as the force required in clamping the package material together is supplied by direct interaction between the first jaw and second jaw. Thus, the normal forces will not be transferred into the main frame of the packaging system to cause unwanted friction. This, in turn, will result in reduced pull forces on the transport system, which is beneficial as the jaws will experience less tension, thus increasing the durability and hence lifetime of the system.

The magnetic element of the second jaw may be constituted by a magnetic disc, but may also constitute other non-disk shaped objects.

In order to achieve less strain to the package material during clamping, the second jaw may comprise a housing and a shaft connected to the magnetic element, wherein the shaft is spring-loaded in relation to the housing.

The first jaw may be movable in relation to the second jaw, but alternatively, the second jaw may be movable in relation to the first jaw. Both jaws may be movable with respect to the frame of the filling machine to which the jaws are connected or attached, or alternatively the first jaw or the second jaw may be static with respect to the frame of the filling machine. The first jaw or the second jaw may comprise an inductor device having a coil conductor, which interact with the packaging material.

The electromagnet may be provided with energy via inductive power transfer. Also the inductor device may be provided with energy via inductive power transfer. The inductive power transfer is advantageous as it enables power transfer to proceed uninterrupted without need to have an electrically conductive path between the power source and the electromagnet/inductor device at all times.

The magnetic element may be spherically suspended in said second jaw. The first jaw may comprise a first electromagnet and a second

electromagnet, and said second jaw comprises a first magnetic element and a second magnetic element, said first electromagnet being aligned opposite to said first magnetic element and said second electromagnet being aligned opposite to said second magnetic element.

The first jaw may comprise a first electromagnet and a first magnetic element, and said second jaw comprises a second electromagnet and a second magnetic element, said first electromagnet being aligned opposite to said second magnetic element and said second electromagnet being aligned opposite to said first magnetic element.

According to a second aspect, the objects are achieved in full, or at least in part, by a filling machine for filling packages with a food product, comprising an induction sealing device as described above.

According to a third aspect, the objects are achieved in full, or at least in part, by a method for heat sealing packaging material to produce sealed packages, using an induction sealing device described above. The method comprises the first step of: actuating the electromagnet of the first jaw so that the first jaw and the second jaw attract each other to close the gap in- between them and clamp the packaging material. The method further comprises the steps of: actuating the inductor device to seal the packaging material, deactivating the inductor device, and deactivating the electromagnet to release the first jaw and the second jaw from each other. Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, component, means, step, etc.]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise.

Brief description of the drawings

The above objects, as well as additional objects, features and advantages of the present invention, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of preferred examples of the present invention, when taken in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic view of a sealing device according to one exemplary example of the disclosure.

Fig. 2 is a drawing illustrating a side view of the example example of

Fig. 1 .

Fig. 3 is a schematic view of a sealing device according to another exemplary example of the disclosure.

Fig. 4 is a schematic view of a sealing device according to yet another exemplary example of the disclosure.

Detailed description of preferred examples of the invention

Fig. 1 illustrates a sealing device 100 according to one example of the disclosure. The sealing device 100 comprises a first jaw 1 10 comprising an electromagnet 1 12 and a second jaw 120 comprising a magnetic element 122. The second jaw 120 is arranged opposite to the first jaw 1 10 to form a gap adapted to receive the packaging material. The first jaw 1 10 and the second jaw 120 are attracted to each other upon actuation of the

electromagnet 1 12 to close the gap and clamp the packaging material between the first jaw 1 10 and the second jaw 120. The package material is compressed between the first and second sealing portions 1 14,126 of the jaws 1 10,120.

This way the closing and opening of the first jaw 1 10 and the second jaw 120 will be realised without letting the normal forces be transferred into the main frame to which the jaws 120,130 are mounted. Such a transfer of forces is a problem since it may risk causing friction between the moving and stationary parts of the transport system of the filling machine of which the sealing device 100 is a part. Increased friction results in increased pull forces in the transport system, which in turn results in higher mechanical stress to the jaw system causing shorter life-time of its components.

The second jaw 120 is movable with respect to the first jaw 1 10 by means of the second jaw 120 being rotatable using a hinged connection 128. Naturally, other alternatives are possible, such as e.g. that the first jaw is movable with respect to the second jaw, or both jaws 1 10,120 are movable with respect to its supporting frame. Naturally, this relative movement between the jaws 1 10,120 is not limited to an angular movement by means of a hinged connection 128, but could also be realised using for instance transversal movement of the first jaw 1 10 and/or second jaw 120 for instance in sliding grooves.

The magnetic element 122 of the second jaw 120 may be a magnetic disk. The material of the disk should be magnetic, but different materials may be used, such as for example ferromagnetic metals and alloys, ferromagnetic liquids.

The second jaw 120 comprises an inductor device 124 having a coil conductor which interacts with said packaging material. The purpose of the inductor device 124 is to heat the packaging material to a temperature sufficient to seal the material, the heating being realised by inducing loss currents in a metal layer part of the packaging material that is present between the jaws 1 10,120. This ensures a localized heating which melts the heat seal plastic material locally. Alternatively, the heating may be realised by inducing loss currents in the first sealing portion 1 14. This may be

advantageous when using package materials without a metal layer. In an alternative example, the second jaw 120 comprises the inductor device 124.

The power supplied to the inductor device 124 may be realised using inductive power transfer. Thus power may be transmitted without the need of establishing a physical conducting loop to the inductor device. The power supplied to the electromagnets may also be realised using inductive power transfer.

The magnetic element 122 may alternatively be spherically suspended in the second jaw 120.

The actuation between the first and second jaw 1 10,120 will now be described in more detail with reference to Fig. 2 illustrating the side view of the example shown in Fig. 1 . The second jaw 220 comprises a housing 224 and a shaft 226 connected to the magnetic element 222 wherein the shaft 226 is spring-loaded in relation to the housing 224. This is realised using a disk spring 228, but may also be realised for instance using other types of springs or elastic materials.

Fig. 3 illustrates a sealing device 300 according to another example of the disclosure. In this example , attractive forces between the jaws 310,320 are created on both sides of the package material, this being realised using two electromagnets on either side of the sealing portions 314,326. The first jaw 310 comprises a first electromagnet 312 and a second electromagnet 316. The second jaw 320 comprises a first magnetic element 322 and a second magnetic element 330. The first electromagnet 312 is aligned opposite to the first magnetic element 322 and the second electromagnet 316 is aligned opposite to the second magnetic element 330.

Fig. 4 illustrates a sealing device 400 according to another example of the disclosure. The first jaw 410 comprises a first electromagnet 412 and a first magnetic element 416, and the second jaw 420 comprises a second electromagnet 430 and a second magnetic element 422. In this example the first electromagnet 412 is aligned opposite to said second magnetic element 422 and said second electromagnet 430 being aligned opposite to said first magnetic element 416. An example of a method for heat sealing packaging material to produce sealed packages will now be described. The method comprises the use of a sealing device 100, the sealing device 100 comprising a first jaw 1 10 comprising an electromagnet 1 12 and a second jaw 120 comprising a magnetic element 122. The second jaw 120 is arranged opposite to the first jaw 1 10 to form a gap adapted to receive said packaging material. The second jaw 120 further comprises an inductor device 124. The method comprises the first step of: actuating the electromagnet 1 12 of the first jaw 1 10 so the first jaw 1 10 and the second jaw 120 attract each other to close the gap and clamp the packaging material. The method further comprises the second step of: actuating the inductor device 124 to seal the packaging material, deactivating the inductor device 124, and deactivating the

electromagnet 1 12 to release the first jaw 1 10 and the second jaw 120 from each other.

It is understood that a sealing device according to the disclosure herein can be for instance an induction sealing device.

It is understood that other variations in the present invention are contemplated and in some instances, some features of the invention can be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly in a manner consistent with the scope of the invention.