A method for the continuous production of space bags and - sacks with a valve opening

摘要

1,008,558. Block-bottom valve bags. WALTER DURBECK PAPIERSACKFABRIKEN G.m.b.H. June 29, 1962 [June 30, 1961; Aug. 5, 1961; Jan. 8, 1962], No. 25157/62. Heading B8K. [Also in Division B5] At least two corners of a valve sack formed from gussetted tube are welded, as at 17 (Fig. 14) so that the inturned portions of the gussets are welded to the side wall, but not to one another, as indicated in Fig. 15; these welds ensure that the sack takes up a block form when filled. Three of the corners may be treated in this way, and a valve is formed by folding in the remaining corner about the line x-x (Fig. 1) to form the equivalent of one end of a diamond fold. The ends 15, 16 (Fig. 14) of the bag are welded. These welds may be interrupted adjacent the gussets, where the welds 17 provide a complete seal, or, alternatively, the welds 15, 16 may be produced to the edges of the tube and the welds 17 formed as spot welds. The valve corner may be formed with a slit 12 (Fig. 10) to provide a long valve 8, 9, or an extension may be secured on to the portion 8, 9. An insert may be welded over the valve corner, when this is opened out as shown in Fig. 12, and this insert may extend outside the bag to provide a valve portion which can be bent over for sealing. The bags may be welded and cut from plastie tube as indicated in Figs. 16 and 18, so that extensions 8, 9 are left at the valve corners. The weld 16 (Fig. 16) is preferably made only after the tube has been opened up, the valve folded in, and the tube closed again. The tube may be laminated of different materials.