How do you avoid the changing speed and reverse taper tension of the simple rewinder?
Option 1: Add closed-loop speed control using feedback from an encoder monitoring a non-slipping idler roller. Add diameter compensation to the unwind torque control by adding some form of diameter measurement.
Option 2: Control speed at the unwind, adjusting RPMs proportional to the decreasing unwinding roll diameter. Drive the winding roll in torque control, allowing the tension to decrease as the winding roll diameter increases.
Option 3: Add a pacer section and upgrade to a two-tension zone process, using a single motor to drive the pacer section and also the input side of a clutch to control winding torque.
Though Option 2 is a clever, simple system that compensates for Option 1 drawbacks, my preference is for option 3. I think the two-zone web line with a pacer should be the foundation for all web lines.