Patent ID: 7188458

Claim:
A machine for making filter bags of tetrahedral shape for infusion products, the machine comprising a production line defined by a series of operating stations where filter bags made from a continuous flattened tube of filter paper are formed, filled with respective doses of infusion product and subjected to successive cuts and closing seals, the production line extending in a horizontal direction and comprising, in succession, a first sealing station for making the first longitudinal seal to form the tube to extend in a direction parallel to the horizontal direction the production line extends; a second tube sealing station for making a succession of transversal seals on the tube transversally to the horizontal direction the production line extends; a cutting station for cutting the tube at the transversal seals to create a succession of filter bags in the process of being formed, each having a sealed bottom end and an unsealed end; an opening station for opening the unsealed end of each filter bag; a dosing station for dosing the infusion product, where a dose of the product is inserted into the filter bag through the unsealed opened end; and a third sealing station for making a seal that closes the end of each filter bag that is still open, the closing seal extending in a direction transverse to the longitudinal seal and to the transversal seal; a transfer station provided between the cutting and opening stations, wherein, in the process of being formed, each filter bag is picked up from the cutting station and fed to the opening station by conveyor means, wherein the conveyor means comprises a revolving drum designed to feed the filter bags along a curved stretch of the feed path in the line passing through the opening, dosing and third sealing stations, wherein the revolving drum supports retaining/stabilising means for picking up and holding the filter bags on the revolving drum, and wherein the retaining/stabilising means comprise: pairs of grippers, each of which picks up a single filter bag and is eguipped with a pair of first filter bag support rods parallel to each other and extending perpendicularly to the grippers, a pair of second rods centrally attached to the grippers, extending at an angle to the pair of first rods, and diverging from each other in such a way as to form a V-shaped element with pointed end at the pair of grippers; and a first rigid element and a second rigid element designed to permit each filter bag to be positioned at the dosing station.