Proceedings of the International Conference on Web Handling

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https://openresearch.okstate.edu/handle/20.500.14446/321637

This collection contains papers which compose the proceedings of the International Conference on Web Handling held at Oklahoma State University from 1991-2019.

A web is a continuous, thin, and flexible material which is transported under tension through various processes including printing, drying, coating, laminating, etc. prior to being converted to a final product. Web processing pervades many automated industries. Web handling is the engineering science underlying the transport of webs through processes successfully without incurring material defects and losses. Webs are often stored in a wound roll format for convenience until the rolls of web are required in a process. The mechanics of winding and rewinding webs is a complex issue of nonlinear mechanics. During transport of the web through a process the web lateral and longitudinal mechanics, dynamics and control become issues. A web has little ability to react compressive stresses such that web wrinkling instabilities are common and often result in material rejection. Air entrainment is often encountered in winding and as the web encounters intermediate rollers. Web flutter is an issue in process lines in which the web velocity may be high and air jets may impinge the web. Thus a number of problems of engineering interest requiring understanding and solution exist within web handling.

This event provided a forum in which engineers and scientists of various countries could present results of their research and exchange ideas in this multi-faceted area of automated manufacturing.

Now showing 1 - 5 of 429

New model for the steady state deformation and friction of webs on rollers
(Oklahoma State University, 2017-06) Jones, Dilwyn P.
A web moving through process machinery interacts with rollers through frictional forces, which may change its direction of motion and tension. By modelling the web as a beam, these forces can be calculated from its tension, curvature and angle, at all points in contact. In turn, the forces can be combined to give distributed forward and lateral forces and a distributed moment, which determine the beam deformation. This approach was introduced in an earlier paper [1], and applied quantitatively to the "stick zone", where web and roller surface velocities match. Now it has been extended to microslip zones in steady state, the transitions to stick zones, and free spans.
Spatially dependent transfer functions for web lateral dynamics
(Oklahoma State University, 2017-06) Cobos Torres, E. O.; Pagilla, Prabhakar R.
In this paper we derive spatially dependent transfer functions for web span lateral dynamics which provide web lateral position and slope as outputs at any location in the span; the inputs are guide roller displacement, web lateral position disturbances from upstream spans, and disturbances due to misaligned rollers. This is in sharp contrast to the existing approach where only web lateral position response is available on the rollers. We describe the inherent drawbacks of the existing approach and how the new approach overcomes them. The new approach relies on taking the 1D Laplace transform with respect to the temporal variable of both the web governing equation and the boundary conditions. One can also obtain the web slope at any location within the web span with the proposed approach. A general span lateral transfer function, which is an explicit function of the spatial position along the span, is obtained first followed by its application to different intermediate guide configurations.
Boundary conditions for lateral deformation of webs transiting rollers in roll-to-roll process machines
(Oklahoma State University, 2017-06) Good, J. K.; Ren, Yao; Shi, Jinxin
The lateral deformations of webs in roll-to-roll (R2R) process machines can affect the quality of the manufacturing process. The lateral registration of the web in successive R2R processes can determine whether a product will function as designed. Herein a unified theory is presented that explains how imperfections in rollers, their alignment and length nonuniformity (camber) in webs can affect the steady state lateral deformation and hence registration. Enhanced understanding of steady state lateral deformation of webs transiting free spans and rollers will provide insight for advanced control methods that account for the effects of web deformation in minimizing registration error. The validated results show that the lateral deformations can be predicted with closed form equations. In some cases the boundary conditions which are integrated into these equations must be determined using dynamic simulation.
Roller nip deflections
(Oklahoma State University, 2017-06) Cole, Kevin; Schneider, Brooks
Rubber covered nip rollers are used in many web handling and processing applications. Successful use of these systems requires an accurate knowledge of the impact of various design and process parameters on key response metrics such as nip pressure and surface speed axial uniformity. These metrics are important since they are directly correlated to operational and functional requirements of nipping processes. Axial variations occur primarily due to roller shell bending, which arise from externally applied end loading forces. The non-linear radial compressive characteristics of elastomeric coverings that are often a part of such systems contributes to system complexity. Previous papers have presented a two-dimensional analytical model that relates force and deformations of rubber rollers in contact with other rollers. In the present paper, a three-dimensional model is presented that extends the previous model by incorporating shell bending deflections. In addition to the non-linearity due to the compressive characteristics of rubber coverings, the model also includes the ability to include other non-linear effects such as roller diameter non-uniformity and misalignment, or skew, of the roller's rotation axes. The model is used to demonstrate that the use of crowning or skewing must not only account for geometric effects but also for the nearly incompressible nature of rubber coverings to successfully mitigate axial nip pressure variation that otherwise is present in end-loaded nip roller systems.
Explicit simulations of wrinkle formation due to web non-uniformity
(Oklahoma State University, 2017-06) Fu, Boshen; Gilgenbach, Eric; Nackers, Katie; Brumm, Russ
It is very common to laminate different materials together and then form, transport and process a web with non-uniform structure in the product manufacturing industry. The periodic media analysis (PMA) method in Abaqus/Explicit [1] has been applied to simulate web wrinkle formation due to web non-uniformity during web transportation. This is a further application of previous PMA simulation models [5]. In this work, an experiment has been conducted to test a web structure including two materials with significant differences in terms of thickness and material properties running through rollers. Wrinkles have been observed during the experiment. Based upon the experimental setup, a web handling model is generated using the PMA method. This model can capture wrinkle formation due to web non-uniformity which agrees with experimental observation. The model and information provided by this model can be used to study wrinkle formation due to similar root causes and explore solutions to prevent wrinkles from occurring in future applications.

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