US Patent 10369759 Plastic bag making apparatus

In order to successively make plastic bags each of which includes panel portions, side gusset portions and a zipper portion, a web of panel material 9 is folded and folded back along longitudinal folded lines 14, 15 and 16 and longitudinal folded back lines 17 and 18 into superposed two layers having opposite side edges at each of which a folded portion is formed. The web of panel material 9 is slit along the longitudinal folded line 16 into two divided parts after being folded and folded back. The divided parts are separated and spaced from each other. In addition, the folded portions are split at positions into sprit portions and removed at the positions partially, a body of zipper material being disposed between the sprit portions.