Method for making sacks which are open at one end and comprise an outer sack of woven plastics tape fabric
AssigneeWindmoller & Holscher
InventorFrank Bosse
Life of this patent
Estimating the term…
Abstract
Sacks are made from a web comprising a tube of stretched plastics tape fabric woven around a thermoplastic tubular film. The web is continuously fed to a storage device from which two-ply sack lengths are intermittently withdrawn and severed and provided with a stitched base seam. Each severing cut is made to extend through transverse strips of hot-melt adhesive which were applied to both sides of the fabric tube and cooled. After severing and prior to stitching through both plies, the inner ply is provided with a separate base seam by means of welding jaws.
Claims5
A method of making sacks which are open at one end and comprise a load-supporting outer sack of circular woven fabric comprising stretched plastics tapes and a sealing inner sack of thermoplastic film connected thereto by a base seam, the inner sack having a melting point less than the melting point of the outer sack, said method comprising:
- weaving a tube of circular woven fabric defining the outer sack around a flattened tubular web defining the inner sack;
- applying transversely-extending strips of hot-melt adhesive to both sides of the flattened tube of circular woven fabric;
- contacting the strips of applied adhesive with rollers to thereby cool the adhesive;
- separating individual tube sections from the tube by severing cuts through the cooled applied strips of adhesive;
- applying a welding temperature below the relaxation temperature of the plastics tape through the webs of woven fabric to a narrow transverse zone spaced from the adhesive strips for a time period sufficient to form a transverse weld seam in the inner sack;
- and
- applying a base seam engaging the inner and outer sacks to the tube section to complete formation of the individual sack.
Dependencies are inferred from the claim text.