Apparatus for feeding a web in registry between web passes through a processing machine

Apparatus for use with a machine processing a continuous moving web having markings representing repeat lengths applied thereto during a prior web pass through the machine, a draw mechanism for unwinding the web from a wound roll, an adjustable guide roll for applying a maintained tension to the web downstream of the draw mechanism relative to web movement, the apparatus comprising:

• a braking device coupled to the wound roll for braking the web upon unwinding by the draw mechanism;
• an adjustable dancer roll for applying a maintained tension to the web upstream of the draw mechanism;
• the dancer roll being connected to the braking device for establishing a direct relationship between a decrease and increase in web tension, upstream of the draw mechanism, and an increase and decrease in braking effect on the web being unwound by the draw mechanism;
• drive means for operating the machine as well as the draw mechanism;
• means for scanning the speed of the web movement and for scanning the web markings between the adjustable guide roll and the machine for measuring any elongation of the web by the relative positions of the markings;
• first and second remotely controllable and independent means for respectively varying the adjustment of the guide roll and of the dancer roll for varying the maintained tension respectively applied downstream and upstream of the draw mechanism;
• and means responsive to the scanning means for operating the first and second remotely controllable means for varying the maintained tension to the web both downstream and upstream of the draw mechanism in an appropriate direction to maintain registry of the web during passes thereof through the machine.