Effective seal for sack with internal valve - by deforming sack walls temporarily and clamping valve between electrodes

摘要

The upper section of a valve sack having in the zone of the valve opening a layer of material which can be welded by heating, is deformed by the welding electrodes during the sealing operation. The electrodes exert such a pressure on the heat weldable layer, that it is welded right through the deformed walls of the sack. Pref. the layer is formed such that during the deformation of the upper zone of the sack, two walls of the layer lie against each other. Used to seal in a reliable fashion sacks filled with granular and powder form materials. The problem arising esp. in sacks with internal valves, is solved and a leakproof closure is ensured. The contents bring the sack back to its box-like shape immediately.