Heat-sealing device for packaging material

Device for welding a moving packaging material comprising a layer that can be heated by electromagnetic induction and a thermoplastic layer incorporating a welding zone which lies in the direction of movement of the packaging material;

• the welding device comprising an alternating current generator, a coil for transforming the alternating current into a magnetic field, a ferromagnetic element for channeling the magnetic field lines in a specific direction, the magnetic field being oriented so as to cross the packaging material in order to induce heating of the layer that can be heated by electromagnetic induction;
• wherein the welding device comprises a set of ferromagnetic elements which are arranged so that the magnetic field lines cross the packaging material in at least two distinct regions located along the welding zone;
• and wherein the device comprises one or more magnetic screens placed between non-adjacent ferromagnetic elements.

Device for welding a moving packaging material comprising a layer that can be heated by electromagnetic induction and a thermoplastic layer incorporating a welding zone which lies in the direction of movement of the packaging material;

• the welding device comprising an alternating current generator, a coil for transforming the alternating current into a magnetic field, a ferromagnetic element for channeling the magnetic field lines in a specific direction, the magnetic field being oriented so as to cross the packaging material in order to induce heating of the layer that can be heated by electromagnetic induction;
• wherein the welding device comprises a set of ferromagnetic elements which are arranged so that the magnetic field lines cross the packaging material in at least two distinct regions located along the welding zone;
• and wherein part of the ferromagnetic elements are placed in a welding rod, the latter comprising a screen element placed so as to contain the field lines in those ferromagnetic elements.