Patent ID: 6871475

Claim:
An apparatus for sealing a flattened tube ( 34 ) of heat-sealable filter paper to make filter bags for infusion products, where the tube ( 34 ) is made from a web ( 17 ) of filter paper that is sealable by thermal reactivation of a layer of glue, the web ( 17 ) having individual charges ( 19 ) of the infusion product placed on its top surface at suitable intervals and being fed continuously in the horizontal position and then folded onto itself until its longitudinal edges ( 18 ) are juxtaposed, the apparatus ( 250 ) comprising at least one operator block ( 94 ) bearing at least one row ( 251 ) of emitters ( 96 ) designed to give off a gaseous fluid heated to a suitable temperature, the operator block being accommodated inside the tube ( 34 ) being formed, the row ( 251 ) of emitters ( 96 ) being aligned and juxtaposed with the longitudinal edges ( 18 ) of the web ( 17 ) of filter paper, and the emitters ( 96 ) giving off the gaseous fluid onto the faces of the inside edges ( 97 ) of the tube ( 34 ) directly on the glue on the web ( 17 ) of filter paper as it is being folded over around the operator block ( 94 ); the operator block ( 94 ) having the shape of an elongated, tapering solid and being positioned in such a way that its wide end ( 253 ) faces a direction ( 254 ) opposite the direction in which the web ( 17 ) of filter paper is being fed, the operator block ( 94 ) having oblique side walls ( 98 ) which are in contact with the longitudinal edges ( 18 ) of the tube ( 34 ) and which bear the emitters ( 96 ) in such a way that the emitters ( 96 ) face the inside of the tube ( 34 ) for reactivating the glue on the faces ( 97 ), wherein the sidewalls prevent gaseous fluid issuing from the emitters ( 96 ) from passing between the edges ( 18 ) and the oblique side walls ( 98 ).