Apparatus and method for controlling position of an edge of an advancing web of flexible material

A web guide system for moving and guiding a continuous web along a path of conveyance, the web having a width defined along a transverse direction between opposite first and second longitudinal edges of the web, the web guide system comprising:

• a web drive system structured and arranged to pull the web and advance the web along the path of conveyance;
• a tension-reducing device located upstream of the web drive system and positioned to contact a surface of the web and to cause the web to partially wrap about an outer surface of the tension-reducing device, the tension-reducing device being configured to focus tension produced in the web by the web drive system upon the tension-reducing device at a location spaced in the transverse direction from the first longitudinal edge of the web, wherein the tension-reducing device comprises an elongate member extending generally transversely from the first longitudinal edge of the web toward the second longitudinal edge, the web guide system being structured and arranged to cause the web to partially wrap about the outer surface of the elongate member for an angle θ, the outer surface defining a maximum arc distance over said angle θ at said location, and the outer surface being configured such that everywhere between the first longitudinal edge of the web and said location an arc distance over said angle θ is smaller than said maximum arc distance, wherein the elongate member has a fixed end proximate the first longitudinal edge of the web and an opposite free end, and the elongate member has a length between the fixed end and the free end that is less than the width of the web;
• the web drive system being operable to pull the web around the tension-reducing device such that tension in the web is non-uniform across the width of the web and reaches a maximum tension generally at said location and decreases toward the first longitudinal edge of the web to create a zone in the web at the first longitudinal edge having a lower degree of tension relative to the tension in the web at said location;
• and
• a web edge guide positioned to engage the web in said zone and to control transverse positioning of the first longitudinal edge.