Patent ID: 6564983
Filing Date: 2003-05-20
Classification: B31B

Abstract:
A web-tension controller for producing perforation-welded bags from a web of a synthetic resin foil, said web being advanced by an upstream pair of feed rollers and a downstream pair of withdrawal rollers past a perforation-welding head at a tension determined by relative speeds of said pairs of rollers, said web-tension controller comprising:a support located between said pairs of rollers; a pair of guide rollers on said support spaced apart in a direction of travel of said web and engaging one side of said web; a device on said support for emitting a flow of air in a direction of said web from an opposite side thereof, said device comprising a wall having a surface juxtaposed with and substantially parallel to said web between said guide rollers, an air outlet opening in said wall, and blower tube having an outlet communicating with said air opening for producing said flow of air and thereby deflecting said web; and a position detector on said support for measuring a position of said one side of said web, thereby determining a value of web tension, and coupled to at least one of said upstream and downstream pairs of rollers for operating same to control the web tension.