Web handling systems maintain a certain amount of tension in the web and a process speed.&nbsp; Non-circular rolls of material are not uncommon in the real world arising from storing the rolls or imprecise control of parameters.&nbsp; Non-circular rolls at the beginning of a web handling system cause tension spikes in the web as they are unwound.&nbsp; Modeling the tension effects of the non-circular unwind roll is the aim of this paper. A review of numerical models, called primitive elements, for web handling systems is included. The parameters required to describe a web handling system are reviewed. A common proportional-integral controller for the motors is described.&nbsp; The web handling system model, which uses linear and nonlinear elements, is compared with experimental data.Parameters dial in the general model to a specific web handling system.&nbsp; The web, the idlers, and the motors all have specific parameters that characterize each one.&nbsp; Mass, friction, inertia, length, Young's modulus, cross-sectional area, and radius are some of the parameters needed. &nbsp;The numerical models used in this work are first principles models. 
Simple torque balances are the basis for modeling all the rotating parts.&nbsp; The span tension model comes from conservation of mass in a control volume. If the control volume has a movable boundary, a length changing span can be modeled.&nbsp; One kind of element, the dancer, requires more than one equation to model it effectively. A dancer incorporates an idler attached to a movable support.&nbsp; The entire idler moves in response to tension changes in the web.&nbsp; To model one dancer, an idler primitive element, an equation for the movement of the idler support, and two span tension equations are necessary.&nbsp; Obviously, more parameters are required for a dancer.&nbsp; The models are arranged such that the output of one of the models is the input to another, e.g.,\ the unwind roll's tangential speed is the incoming speed required for the span tension model of the first span.Control must be applied to the web handling system.&nbsp; A common PI control scheme will be used in this work to control the position of a dancer in the modeled web handling system.&nbsp; The parameters for control will be discussed. &nbsp;An example using a web handling system that was at Oklahoma State University is given to show the ability of the numerical model to simulate the tension dynamics induced by a non-circular unwind roll.&nbsp; Data was recorded from the web handling system's load cell and dancer.&nbsp; The model state variables are compared to the recorded data and shown to be a good representation of the real web handling system.

Simulating Dynamic Tension Effects From an Out-of-Round Unwind Roll

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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