Patent ID: 8882946

Claim:
Ultrasonic sealing jaw ( 1 ) for sealing portions of plastic film to a tube so as to form a sealing engagement of the portions of plastic film around the circumference of the tube, the sealing jaw ( 1 ) comprising a concave film-tube welding portion ( 7 ) for receiving the tube covered by the plastic films, the film-tube welding portion ( 7 ) being adapted to form the film-tube attachment, and, adjacent to at least one side of the concave portion ( 7 ) of the sealing jaw ( 1 ), characterised in that the sealing jaw comprises a substantially flat film-film welding portion ( 3 , 4 ) for engaging the plastic film and sealing adjacent portions of plastic film to each other in an area adjoining the tube, said film-film welding portion ( 3 , 4 ) defining a top plane ( 10 ) of the sealing jaw ( 1 ), and the film-film welding portion ( 3 , 4 ) comprises along the edge towards the film-tube welding portion ( 7 ) at least one recess with a surface ( 11 ) so as to form a cavity ( 12 ) with an opening towards the film-tube welding portion ( 7 ).