Calibration of segmented tension roll transducing systems

Web tension transducing systems, implemented with a transducing roll (measuring beam) that incorporates only two load-bearing points (one at each end of the transport roll), are uncomplicated relative to conventions for establishing the per-transducer calibration standards and methods of calibration. Multiple (more than two) load-bearing point transducing rolls are not utilized to enhance web tension transduction. As indicated above, the simple two point system is both simple and accurate. However, as web processing machines become faster and wider, and web transport tension control more critical, multiple load-bearing point web transport roll systems have become quite common. When web tension transducing systems are implemented with web transport rolls, which have more than two load-bearing points, variations relative to the conventions for establishing per-transducer calibration standards and methods of calibration result in confusion, and in many cases subsequent web tension transducing errors. This paper discusses the issues involved and provides the basis for the development of compensation factors that could be applied to particular tension transducing configurations.