| 摘要 |
854,499. Making bags. BERGHGRACHT, M. Nov. 27, 1956 [Nov. 28, 1955], No. 36245/56. Class 94(2). Bags of the kind made by folding a blank to U-shape and heat sealing the side margins are formed by a mandrel pressing blanks through a fixed die, the portion of the blank for forming the bag bottom being engaged by a second mandrel to shape the bottom as both mandrels travel with the blank through the die. The side margins are sealed when the blank leaves the die. In one embodiment, a web 1 of thermoplastic coated single or multiple ply sheet material is fed over the die 5 and a blank 4 cut off. An upper mandrel 7, the base of which may be shaped as in Figs. 10, 11 to produce the bottom formation shown in Fig. 1, presses the blank into the die, the blanks side margins entering opposed slots therein. A lower mandrel 10, shaped as in Figs. 12, 13 co-operates with the mandrel 7 as the latter descends. Heat sealing rollers 13, 13<SP>1</SP> grip the emerging folded blank, enabling the mandrel 7 to be withdrawn, and pass the blank downwards while sealing its side margins. At the same time rotary cutters (not shown) trim off surplus material. Both mandrels withdraw and an air jet from a nozzle 16 blows the completed bag onto a discharge shoot 17. In another embodiment, Figs. 18 and 20 (not shown), the mandrels move horizontally between opposed guiding rollers. The side seams are formed by upper and lower heated bars, the upper bars being carried on a vertically movable plate. The bars may be profiled to allow for variations of seam thickness. The die has four sections moveable towards or away from each other by screw adjustment to allow for various thicknesses of material. Resilient rollers are mounted on the die sections to press the blank against the four longitudinal side edges of the mandrels. In the formation of bags in which the corner points extend inwards, the mandrel 10 has a formation similar to that of the mandrel 7 as shown in Fig. 11, while the mandrel 7 is shaped to complement it. |
