Drives for Web Handling

I have seen them on many large film slitter-rewinders, where each centre-wound slit roll is driven by one or more motors located in the arms that hold the core. The arms are mounted on a beam that slowly rotates to accommodate the roll buildup. There are usually 2 beams, with slit webs going to a roll on each beam in turn across the parent web width. The pancake motor geometry allows the chucks to be driven through a belt drive, and makes the arm manageably narrow so that smaller slit roll widths can be made . Larger rolls can be driven by arms with larger motors or two or more identical arms coupled together (so the torques add together and sufficient tension is available). There may also be proprietary technology considerations - some manufacturers offer pancake motors, others standard motors with gears to transmit the drive through 90 degrees.
A second application is providing additional drive to each transport roller. The main drive sets the reference roller speed and provides the basic speed to the others through a belt. Pancake motors provide additional speed through a planetary gearbox, giving a "hamonic drive". This was developed in the 1980's as a way of controlling roller speeds to 0.01% or better, either to compensate for roller diameter differences or provide a known progression of speeds through the machine.

Hi, i am interesting to know if you use pancake motor, or servodisc motor for web handling application. Kollmorgen provide pancake type( PMI acquired by Kollmorgen). let me know you need to know more details.