Heat sealing device

A device for the continuous heat-sealing of packaging containers made of heat-sealable polymeric material, comprising mutually opposite active heads that are associated with respective counter-rotating driving shafts and are subjected to the action of cam elements for moving said heads along a path that is partially parallel to a continuous tubular container that includes the products to be packaged and in which the oppositely arranged active heads, during the rotation of the respective counter-rotating driving shafts, move mutually closer to clamp the tubular container in the region that separates one product from the other, to perform the heat-sealing of said region and the cutting of the container that separates each package from the adjacent one;

• and a planetary-gear system that is interposed between the active heads and the corresponding driving shaft and is adapted to make the individual heads, during the rotation of said driving shaft, perform a revolving motion that keeps them parallel to each other, said system being also adapted to cause the mutual approach of the mutually opposite heads that are associated with each of the counter-rotating shafts, in a mutually parallel relationship along an approach path that is substantially perpendicular to said tubular container, said planetary-gear system comprises a sun gear that is fixed with respect to the driving shaft and at least one plurality of planetary gears that are supported, so that they can rotate freely, by a supporting disk that is rigidly coupled to said driving shaft, such that each planetary gear rotates rigidly with a respective cross-member that is provided with a corresponding active head, the device further comprising additional idler gears interposed between the sun gear and the planetary gears and meshing with both;
• said idler gears being supported, so that they can rotate freely, by said supporting disk so as to roll on the sun gear when the corresponding driving shaft rotates about its own axis, each one of said planetary gears being provided with a slot in which a prismatic end of the corresponding cross-member for supporting the active head engages torsionally but so that it can slide radially.