Abstract: The invention relates to a device for folding and sealing the head of a folded carton made out of a web or blank of cardboard coated on the inside with a thermoplastic layer. The device has levers or supports that carry the folding and pressure-welding tools and that are powered independently of each other by shafts. The result is a structure that is simple and easy to clean. It also allows satisfactory acceptance or introduction of force for the pressure-welding process. Since the force-introduction impact point and a point of contact between the tools that are to be approached to each other like tongs can be located on an axis of pressure, the shafts that pivot and power the lever and support need to accept no forces and accordingly remain free of stress.