Proceedings of the International Conference on Web Handling

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.

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Recent Submissions

  • Publication
    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.
  • Publication
    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.
  • Publication
    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.
  • Publication
    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.
  • Publication
    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.
  • Publication
    Effect of mass transfer on multi-span lateral dynamics of nonuniform webs
    (Oklahoma State University, 2017-06) Brown, Jerald L.
    Since the publication of Shelton's original work [1] on lateral web dynamics in 1968, the cambered1 web has attracted the attention of researchers. Shelton, himself, felt it was a natural "next step" in lateral dynamics. It is not only interesting as a theoretical challenge. It is the simplest case of an important class of lateral handling problems known as baggy2 webs. However, despite considerable effort by many people, it is still considered by many authorities in the field to be an unsolved problem.
  • Publication
    Wrinkling mechanisms of webs with spatially varying material properties
    (Oklahoma State University, 2017-06) Carrle, Jeremy; Lange, Steve; Hamm, Rich; Ba, Shan
    Webs often include variation in caliper or modulus of elasticity as a result of manufacturing variation. Light-weight nonwoven webs are especially prone to these issues because the variation is proportionally more, relative to the average modulus. It is proposed that the length scale variability in fiber orientation and most importantly mass density extends to the mechanical properties of the web, including the degree of orthotropy and Poisson's ratio (neckdown behavior). Finite element simulations show that materials exhibiting this kind of variability (in MD and CMD modulus, and Poisson's ratio), notably with nominally high and low regions alternating in the MD, leads to trough and wrinkle formation. Multiple simulations with varied material properties have led to a greater understanding of the mechanisms and conditions that cause these types of wrinkles.
  • Publication
    Optimizing nipped roller systems
    (Oklahoma State University, 2017-06) Walker, Timothy J.
    Nipped rollers are central to many web converting processes - printing, coating, embossing, calendaring, and winding. Uniform products require uniform load and pressure from the nipping process. Uneven nipping not only creates product variations, but can lead to high levels of waste from web shifting, wrinkling, wound roll defects.
  • Publication
    Measurement of web curl
    (Oklahoma State University, 2017-06) Swanson, Ronald P.
    Generally it is desirable for web based products to have a flat planar shape. Unfortunately coated and laminated products often assume a curved shape. This is a defect commonly called "Curl". The first step in solving most defect problems is an accurate, repeatable and quantifiable measurement system. This paper discusses current curl measurement standards and describes a new measurement method. This method, the Kappa Gauge, which is fast, accurate, inexpensive and eliminates many of the problems of the current measurement standards. The resultant curvature measurement (Kappa) is linear with the moment causing the curl and therefore makes solving curl problems much easier.
  • Publication
    Using a winding model to reduce winding defects
    (Oklahoma State University, 2017-06) Thuer, Amy
    As a roll is wound, stresses in the roll develop - and change as the roll builds. The stresses on each layer in the wound roll influence whether the roll is likely to telescope, star, cinch, yield, block or ooze - to name just a handful of winding defects.
  • Publication
    Effect of mass transfer on multi-span lateral dynamics of a uniform web
    (Oklahoma State University, 2017-06) Brown, Jerald L.
    This paper will show that the acceleration equation used in multi-span lateral dynamic models is a consequence of mass transfer between spans1. Mass transfer effects fully account for the equation currently used in Euler-Bernoulli models and provides an analytical pathway to an acceleration equation that incorporates shear deformation. It also ties together contributions from three other researchers - John Shelton, who pioneered the use of beam theory in models of lateral web dynamics, Lisa Sievers, who proposed the principle of continuity of bending angle and Richard Benson, who was the first to publish an acceleration equation that correctly incorporates shear deformation.
  • Publication
    Impact of large deformations of webs transiting rollers
    (Oklahoma State University, 2017-06) Shi, Jinxin; Markum, Ron E.; Good, J. K.
    Webs are subjected to large out-of-plane deformations when transiting rollers in process machinery. Webs are often treated as membranes in analysis but become subject to significant bending strains when transiting rollers. Anticlastic bending of thick plates is a known phenomenon. The anticlastic effect is often ignored for webs which are thin. The objective of this paper is to demonstrate that the large bending deformations webs are subjected to on rollers influence the internal membrane stresses and deformations in the web. The results will show that the concept of normal entry of a web to a roller has complexity that has previously not been considered. It will be demonstrated that a cross direction tensile membrane stress results from the large deformations that acts to stabilize the web and inhibit wrinkle formation.
  • Publication
    Measurement and quantification of baggy webs
    (Oklahoma State University, 2017-06) Swanson, Ronald P.
    Webs that have crossweb variation in machine direction length are commonly called "Baggy Webs". All real webs have some degree of bagginess. When the bagginess exceeds some quantity, web handling problems such as wrinkling and lateral motion begin to appear.
  • Publication
    Machine direction registration dynamics model of a rotary printing press
    (Oklahoma State University, 2017-06) Rice, Brian S.; Walton, Robert L.
    We derive an analytical model of the machine direction registration dynamics of a continuous-web, electronic line shaft (ELS) rotary printing press. We use the model to quantify the affect of tension disturbances on machine direction registration dynamics with different control schemes. With standard ELS registration control schemes, we show the benefits of using a compensator roller vs. electronic differential gear (advance or retard print cylinder's angular position). Next, we develop a novel cascaded reference control scheme for an electronic differential gear controlled ELS printing press that allows it to rival the performance of a compensator roller controlled ELS printing press. Finally, we demonstrate the benefits of using a cascaded reference empirically on a 6-station rotogravure ELS printing press.
  • Publication
    Study of oscillation
    (Oklahoma State University, 2017-06) Roisum, David R.
    There are many reasons to consider oscillation. Most fall under the overall desire to smear out streakiness in web caliper (basis weight, gage, thickness etc) so that it doesn't build up on some downstream process; most particularly winders. Bagginess and corrugations are just a few of the many 'winding' defects that may be helped by oscillation. However, many defects are too wide to be economically remedied by oscillation. This is because most oscillating systems will require an additional trim loss. This forces an economic tradeoff between defect waste (and/or customer complaint) by not going far enough and trim waste by going too far. Exceptions are blown film because it oscillates the entire width (circumference of the bubble). Yet here we run into another limitation of oscillation that blown film suffers more than most. That is it may not be oscillated nearly fast enough to avoid caliper buildup damage. This paper reviews the motivations in detail as well as the common machinery of oscillation. The paper also reviews the literature on the subject that is, in a word, nearly nonexistent. Next, a simple model is presented that can help guide the process designer in selection of oscillation stroke, speed and shape. Finally, the model results are compared to the nearly nonexistent application guidelines.
  • Publication
    Modeling and computer simulation of zero speed splice unwinds
    (Oklahoma State University, 2017-06) Pagilla, Prabhakar R.
    A computer program for conducting model simulations for zero speed splice unwinds is described in this paper. A typical unwind system consisting of the unwinding material roll, festoon, dancer, and pull rolls is considered. The developed computer model is general enough to be applicable to a variety of unwinds containing these components. The paper also provides a procedure for determining zero speed splicing parameters when the characteristics of the festoon and the splicer, such as number of carriage rollers, festoon capacity, clamp and dwell time, etc., are given; this method can be employed for the selection of splicing parameters, such as acceleration and deceleration profiles, splice diameter, spindle speed profiles, etc. The computer model can predict the transport behavior of webs through the unwinds; this was verified by comparing data from model simulations and experiments on a production unwind. The computer program can be used to evaluate different scenarios of unwind operation prior to actual implementation on production unwinds. Thus, providing a significant benefit in terms of operational efficiency as well as improved process capability.
  • Publication
    Nip mechanics of nano-impression lithography in roll-to-roll process machines
    (Oklahoma State University, 2017-06) Ren, Yao; Good, J. K.
    Nano-Impression Lithography (NIL) has been demonstrated to produce nano features on webs that have value to society. Such demonstrations have largely been the result of NIL processes that involve the discrete stamping of a mold with nano-impressions into a thermoplastic web or a web coated with resin that is cured during the imprint process. To scale NIL to large area products which can be produced economically requires the imprinting to occur on roll-to-roll (R2R) process machines. Nip mechanics is a topic which has been explored in relation to drive nips and winding nips in R2R machines. Nip rollers will be needed to imprint webs at production speeds to ensure mold filling on an imprint roller. The objective of this paper is to demonstrate while the nip roller is required that it can also induce imperfections in the imprinted nano-features. Successful imprinting will require nip loads sufficient to fill the imprint mold and then addressing the nip mechanics which can induce shear and slip that could destroy the nano-features. The objective is to demonstrate through the study of nip mechanics that this shear and slip can be inhibited through the selection of nip materials and tension control of the web entering and exiting the nipped imprint roller.
  • Publication
    Winding mechanics of laminate webs
    (Oklahoma State University, 2017-06) Pan, Sheng; Markum, Ron; Good, J. K.
    Models that describe the residual stresses due to winding single layer webs at the end of roll-to-roll manufacturing machines are mature. These models have been used to reduce or avoid defects that are due to winding. Many laminated products exist where two or more webs have been joined to form a thicker composite web. The properties of each layer provide a unique functionality to the product. No laminate winding models exist in the literature. This paper will focus on the development of a laminate winding model and lab test verification of the model.
  • Publication
    Optimizing idler diameter
    (Oklahoma State University, 2017-06) Lynch, Ronald
    The idler is probably the most common roller in web handling, but it is one of the least studied. It influences both the highest and lowest tension we can run, and can defeat the most sophisticated tension control schemes. Inertia and bearing drag both upset tension during transient conditions. Idler diameter is one variable that can affect both. Too small a diameter can result in wrinkles caused by deflection, or web damage from bending stress. Too large an idler can result in loss of traction from air entrainment and unnecessarily high equipment cost. Hopefully, there is a diameter that can satisfy all requirements. This paper looks at several factors that must be considered while selecting the best diameter for idlers to minimize their impact on the web path.
  • Publication
    Preventing negative issues at nip roller
    (Oklahoma State University, 2017-06) Bass, Tom; Nagahori, Atsushi
    Dealing with film scratches, wrinkles, and air entrapment is a problem that many converters are faced with on a regular, if not daily basis. Part of the problem is the rollers they have to work with at the nip point. Granted, rubber covered rollers at the nip point is a proven technology that has been utilized for many years. However, with the technological advancements in designing and manufacturing Carbon Fiber Reinforced Plastic (CFRP) rollers there are benefits to consider in utilizing this technology at the nip roll.