| 摘要 |
Apparatus and methods for removing overlapping material such as occurs in wrinkles and folds in the open edge of a pliable package, such as plastic prior to sealing the package. The apparatus includes a set of transport belts which grip the open edges of the package and move them in a selected direction of travel. The open package edges then encounter a set of opposing programmable pinch wheels before the trailing edge of the package leaves the first set of transport wheels. The pinch wheels have a rate of rotation selected to move the package edge along the direction of travel at a speed faster than that provided by the transport belts. Consequently, the leading package edge is pulled taut. Subsequent to the trailing edge of the package leaving the transport belt, the leading edge of the open package edges encounters a second set of transport wheels which also move the package edge in the selected direction of travel. Upon this engagement, and while a substantial portion of the package edges still must travel through the programmable pinch wheels, rotation of the pinch wheels is stopped and the pinch wheels are then driven so as to be biased to a "null" position or against allowing the package edges to move in the direction of travel. They are also programmed to have less torque available to maintain the zero or "null" bias than the torque provided to the second set of transport wheels. Thus, if a fold or wrinkle is encountered it will be eliminated as the pinch wheel passes over the fold and then returns to its zero or "null" position.
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