Bag forming machines

Abstract

The specification discloses apparatus for forming individual heat sealed articles, e.g., tubes or bags, from a strip of two superimposed layers of heat sealable material or of a material coated, or impregnated, with a heat sealable material which apparatus comprises means to feed the strip in a zig-zag configuration and means for welding together the layers of the strip at or adjacent the transverse crests of the strip located on one side of the zig-zag. The welding means comprise a single continuous welding device and the feed means includes means for supporting the strip at the transverse crests located on the mentioned one side of the zig-zag and for presenting those crests to the welding device.

We claim: 
     
       1. Apparatus for forming individual heat sealed articles, e.g. tubes or bags, from a strip of two superimposed layers of heat sealable material or of a material coated, or impregnated, with heat sealable material, said apparatus comprising: a welding device comprising a continuous surface of heat transmitting material;   means to heat said surface; .[.and.].   means for feeding a strip of material in a zig-zag configuration along a path which extends along at least a part of said continuous surface, said feeding means comprising members supporting said strip at the transverse crests located on both sides of the zig-zag to present the crests on one side of said zig-zag to said continuous surface.Iadd.; and .Iaddend.   .Iadd.said continuous surface being cylindrical and being mounted for rotation when engaged by the moving strip. .Iaddend. .[.2. Apparatus as claimed in claim 1, wherein said continuous surface is cylindrical and is   
     
     
        mounted for rotation when engaged by the moving strip..]. 3. In apparatus for forming individual heat sealed articles, e.g., tubes or bags, from a strip of two superimposed layers of heat sealable material or of a material coated, or impregnated with heat sealable material, which apparatus comprises means to feed the strip in a zig-zag configuration and means for welding together the layers of said strip at or adjacent the transverse crests of said strip located on one side of the zig-zag, the improvement wherein: said welding means comprises a cylindrical surface of heat transmitting material mounted for rotation, when engaged by the moving strip, on an eccentric portion of a shaft which is itself rotatably mounted on a support structure to move the cylindrical surface towards or away from the zig-zag strip, and means for heating said cylindrical surface; and   said feed means comprises means for supporting said strip at the transverse crests located on both sides of the zig-zag and for pressing said crests on said one side of said strip against said cylindrical surface, so that by moving the cylindrical surface towards or away from said zig-zag strip   
     
     
        the width of the finished heat sealed articles can be altered. 4. Apparatus as claimed in claim 3, wherein said means for heating said cylindrical surface comprises a plurality of heating elements mounted with 
     
     
        said cylindrical surface. 5. Apparatus as claimed in claim 4, wherein said heating elements are secured with respect to said shaft.