Kunststoff-Ventilsack, der aus einem an den Enden durch Verschweissen der Kanten verschlossenen Seitenfaltenschlauchabschnitt besteht

摘要

971,290. Making plastics valve bags. M. GENNERICH, and A. WINDMOLLER, [trading as WINDMOLLER & HOLSCHER]. March 1, 1963 [April 9, 1962; May 9, 1962], No. 8382/63. Heading B5D. [Also in Divisions B6 and B8] A gusseted plastics valve bag is made by flattening open one corner of a gusseted tube, inserting a valve sheet 10 (Fig. 1) beneath the comer fold 6 and welding it thereto at 11, folding the corner of the tube back to its original position and welding the valve to the walls at 15 and 16, a weld preventing means having previously been inserted. Each operation is made with the bag stationary, the movement between operations having been in the longitudinal direction of the tube. The bag is now moved transversely to strip it from the stationary weld preventing means and then again longitudinally to form an end weld. The bag is moved transversely and then back longitudinally to form the other end weld and may then be moved to another working position to form diagonal corner welds of the gussets to the bag walls at the non-valve comers. The gusseted bag tubes are initially stacked at 76 (Fig. 28), resting on angle ledges 77, 78 and rollers 79 which roll backwards and forwards without sliding on the bottom of the pile. In the position 791 the lowermost tube is gripped by suction openings 80 in the roller and is then wound on to the roller as it simultaneously rotates and moves back to its original position. The lower tube wall 1 is the first to be pulled over the angular ledge 77 and is thus separated from the upper wall 2. In the lower position the grippers 82 secured to rotating chains 81 are pivoted into the open tube, the air suction is turned off at 80 and the opened tube proceeds to the further working positions. Retaining fingers 83 on the grippers 82 prevent the wall 1 from collapsing. The valve sheet may have its internal end of thinner material than the external end, either by welding a thinner sheet to the inner end of the first sheet or by using a material of varying thickness. The varying thickness may be obtained either by extending a sheet with varying cross-section across its width or by rolling a sheet of material at intermittent intervals along its length.