Abstract: A method of controlling an inductive heating circuit, having a varying load, to seal a packaging material is provided. The method comprises generating AC power of at least two frequencies on at least one inductor in the inductive heating circuit; determining of the resulting phase shift in the inductive heating circuit from the current generated at the at least two frequencies; determining the impedance of the inductive heating circuit for each of the at least two frequencies; determining a load characteristics of the inductive heating circuit based on the relationship between the determined impedance and the determined phase shift; determining an impedance operating range; and selecting an AC output frequency for an induction power generator based on the load characteristics which results in the least amount of phase shift from a set ideal value and which is associated with an impedance that is within the impedance operating range.

Abstract: A method of controlling an inductive heating circuit, having a varying load, to seal a packaging material is provided. The method comprises generating AC power of at least two frequencies on at least one inductor in the inductive heating circuit; determining the resulting phase shift in the inductive heating circuit from the current generated at the at least two frequencies; determining the impedance of the inductive heating circuit for each of the at least two frequencies; determining a load characteristics of the inductive heating circuit based on the relationship between the determined impedance and the determined phase shift; determining an impedance operating range; and selecting an AC output frequency for an induction power generator based on the load characteristics which results in the least amount of phase shift from a set ideal value and which is associated with an impedance that is within the impedance operating range.

Abstract: A device for adjusting the transverse position of a strip of packaging material on a packaging machine for producing packages containing a pourable food product, the device having a slide movable crosswise with respect to the strip and carrying a gripping member for moving the strip transversely; and a system for automatically adjusting the position of the slide in response to signals generated by optical sensors for detecting respective limit positions of the strip.

Abstract: A method of fitting pull-off tabs (2), made of heat-seal material, to strip packaging material (4) having a number of through openings (3) and covered, on the opposite side to that to which the tabs (2) are fitted, with at least a first and a second lamination layer (10, 11, 12, 9) made respectively of heat-seal material and electrically conducting material and covering the openings (3); the method including the step of joining each tab (2) to the packaging material (4) at a respective opening (3) by simultaneously performing hot-plate sealing and induction sealing operations. (FIG.