Method and apparatus for dynamically controlling a web printing press

摘要

A method for dynamically controlling a driver of a nip roller in a web printing press includes controlling the speed of the driver in a tension-control mode during a phase of printing press operation and in a velocity-control mode during another phase of printing press operation. The controlling of the speed of the driver in the tension-control mode is based on the tension in the web upstream of the nip roller so as to maintain the tension at a desired tension value. The controlling of the speed of the driver in the velocity-control mode is based on a predetermined driver velocity ratio for maintaining the web tension. The tension-control mode may be employed during press start-up as the web accelerates to operating speed. The velocity-control mode may be used during printing operations of the press.