INDUCTION SEALING DEVICE AND CORRESPONDING METHOD FOR PRODUCING PACKAGES OF POURABLE FOOD PRODUCT

摘要

An induction sealing device which may be used for producing packages of pourable food products by transversely sealing a tube (13) of sheet packaging material having at least one layer (12) of induction-heatable material covered with plastic material (16). The sealing device has: a generator (3) for generating an alternating power signal S(omega); an inductor (4) receiving the alternating power signal S(omega) to induce a parasitic electric current in the layer (12) and locally melt the plastic material (16) to form a transverse seal; and a matching circuit (7) for achieving optimum power transfer between the generator (3) and the inductor (4). The matching circuit (7) includes an inductive-capacitive circuit, in which the capacitance of a variable-capacitance capacitive element (20, 24, 25, 26, 27) is adjustable so that the current-voltage phase angle is close to zero.