Optimizing Tension Control Performance in Center Driven Winders

摘要

Center driven winders and unwinds drive into a constantly changing load as they process andregulate web tension. The changing roll diameter requires the control system must continuouslyadapt to the correct spindle speed and effectively handle the changes in roll mass while providingaccurate web tension control performance.Typical internal components of a center wind tension control system can include; a diametercalculator, a closed loop process controller (i.e. PID) and an inertia calculator. Through theseinterconnected modules, the tension controller, drive speed and current controller’s setpoints andperformance variables are established. These tension controller components and the processvariables they produce are all directly dependent on the accuracy of the actual roll diametervariable used in the process.The accuracy of the diameter calculator component is highly critical to the systems performanceto the point that it may be considered the most important element in the control system.Actual roll diameter can be measured with a sensor or calculated with input values of web andspindle motion. Since measuring roll diameter is normally only suitable for the initial or startingdiameter setting, actual diameter is traditionally calculated constantly during the process. Multipletechnologies exist for calculating the running diameter, but modes that utilize actual or derivedposition changes in the web and spindle can offer greater performance.This paper discusses tension control concepts, potential methods of diameter calculation, theoptimum diameter calculation modes and the intricate interaction between the diametercalculation and the tension technology controller in regard to performance.