The invention is a device for welding two overlapping film sections situated on one side of a goods stack. The device includes a welding bar with a welding surface oriented in the direction of the film sections to be welded. The spacing between the welding bar and the film sections is reducible. The welding surface is elastically deformable into a concave course and/or to a convex course between its two ends. At least one displacing device adjusts the course of the welding surface to a concave and/or to a convex course. The displacing device displaces welding bar. A control unit of the welding bar individually controllable, such that the curvature of the welding bar is adjustable to the contour of the side of the goods stack in the region of the film sections to be welded with one another for the subsequent welding of the overlapping film sections.