Method and apparatus for making flat bags having rectangular bases from a two-ply web of thermoplastic film

Abstract

Abstract METHOD AND APPARATUS FOR MAKING FLAT BAGS WITH RECTANGULAR BASES FROM A TWO-PLY WEB OF THERMOPLASTIC MATERIAL, THE TWO PLIES BEING JOINED ALONG ONE LONGITUDINAL EDGE OF THE WEB AND UNCONNECTED ALONG THE OTHER EDGE. THE METHOD COMPRISES THE STEPS OF: APPLYING SEPARATING WELD SEAMS TO THE WEB AT INTERVALS CORESPONDING TO THE WIDTHS OF THE FLATTENED BAGS TO BE MADE, THE SEAMS EXTENDING FROM ONE LONGITUDINAL EDGE AT RIGHT ANGLES THERETO BUT ONLY ACROSS A PART OF THE WEB WIDTH SO AS TO DEFINE THE BOTTOM OF ONE BAG BETWEEN EACH PAIR OF ADJACENT SEPARATING SEAMS, SPREADING THE PLIES APART FROM WITHIN THE WEB BETWEEN THE SEPARATING SEAMS IN A DIRECTION SUBSTANTIALLY NORMAL TO THE WEB TO AN EXTENT CORRESPONDING TO THE DESIRED WIDTHE OF EACH RECTANGULAR BAG BASE SO THAT OUTWARDLY PROJECTING TRIANGULAR POCKETS ARE FORMED AT EACH BAG BOTTOM ADJOINING THE BASE, NIPPING OFF THE TRIANGULAR POCKETS BY MEANS OF FURTHER WELD SEAMS EXTENDING TRANSVERSELY TO THE SEPARATING SEAMS ACROSS THE REMAINING PART OF THE WEB WIDTH UP TO THE OTHER LONGITUDINAL EDGE SO AS TO DEFINE THE FULL HEIGHT OF THE BAGS AND TO SEVER EACH BAG FROM THE WEB. THE APPARATUS COMPRISES CONVEYING MEANS FOR INTERMITTENTLY FEEDING THE WEB IN STEPS EQUIVALENT TO THE WIDTH OF EACH BAG AND A FIRST SEPARATING AND WELDING BEAM RECIPROCABLE WITH RESPECT TO THE WEB, THE FIRST SEPARATING AND WELDING BEAM BEING ADAPTED TO APPLY BAG BOTTOM DEFINING SEPARATING SEAMS TO THE WEB WHEN THE WEB IS STATIONARY. AN EXPANSIBLE FORMER IS POSITIONED DOWNSTREAM OF THE FIRST BEAM AND IS ADAPTED TO SPREAD THE PLIES APART BETWEEN THE SEPARATING SEAMS WHEN THE WEB IS STATIONARY. THE FORMER IS CARRIED BY A FLAT SUPPORTING ARM THAT IS RECIPROCABLE TRANSVERSE TO THE LONGITUDINAL WEB EDGES TO MOVE THE FORMER IN AND OUT OF EACH BAG BOTTOM. A PAIR OF SEPARATING AND WELDING JAWS ARE MOVABLE TOWARDS AND AWAY FROM THE WEB AND ARE ACTUATABLE TO NIP OFF THE POCKETS OF EACH BAG BOTTOM WHEN THE FORMER IS LOCATED THEREIN. A SECOND SEPARATING AND WELDING BEAM IS LOCATED DOWNSTREAM OF THE FORMER AND WELDING JAWS, IS MOVABLE TO AN FROM THE WEB AND IS ADAPTED WHEN THE WEB IS STATIONARY TO EXTEND EACH OF THE SEPARATING SEAMS AND SEVER EACH BAG FROM THE WEB.

Inventors

• 👤 August Schwarzkopf

Bibliographic Details