Web Handling Research Center
Air Jet Technology in Web Handling
The goal of the research is to develop new methods of handling flexible materials without contact, mainly using air jets. One important phenomenon involved in this research is the Coanda effect. The behavior of an air wall jet ejected from a slot nozzle toward a curved surface was modeled and examined. The study was extended by including the effect of a web placed near the Coanda nozzle. The aerodynamic pressure and traction (frictional force) on the web subjected to the Coanda air jet were determined experimentally and also computationally. Design guidelines for energy-efficient air nozzles were developed. Also an analytical model was developed for prediction of the uniformity of flow profile of the air jet from a slot nozzle.
Sponsor: Web Handling Research Center
PI: School of Mechanical Engineering Technology: Young B. Chang
Lateral Statics of a Web Over an Air Reverser
Air reversers are noncontact supporting devices with a large wrap angle, typically 180 degrees. One problem of a web supported by air reversers is that the web, when disturbed, tends to oscillate with increasing amplitudes as it moves downstream. This phenomenon is called weaving or weave amplification. Misalignment at a splice, which in turn causes tilting of the web, is considered one major disturbance that triggers this type of instability. Perforated-drum type air reversers are considered in this research. Two-dimensional analyses and computations were done to predict the aerodynamic forces on a tilted web over an air reverser. The study model will be extended to include the three-dimensional effect. Experimental verification of the analytical models will be conducted by measuring aerodynamic pressure profile under the web, mass flow rate of the air, and lateral deflection of a stationary web.
Sponsor: Web Handling Research Center
PIs: School of Mechanical Engineering Technology: Young B. Chang, Kenneth Belanus
Web Wrinkling Prediction and Failure Analysis
Web quality degradation can occur if wrinkling takes place across the rollers or inside (or upon) wound rolls. This research is concerned with determining how wrinkles form as a function of web line and web material parameters.
Sponsor: Web Handling Research Center
PIs: School of Mechanical and Aerospace Engineering: Keith Good, John J. Shelton
Viscoelastic & Hygroscopic Effects on the Formation of Baggy Lanes in Webs
The objective of this project is to develop methodologies to wind viscoelastic webs to produce rolls that have dimension stability to minimize the formation of baggy lanes. Research will be focused on the understanding of baggy lane formation in viscoelastic webs with non-uniform width direction thickness profile.
Sponsor: Web Handling Research Center
PI: School of Mechanical and Aerospace Engineering: Hongbing Lu
Out-of-Plane Dynamics of a Web at an Air Reverser
Sponsor: Web Handling Research Center
PI: School of Mechanical and Aerospace Engineering: Peter M. Moretti
The Role of Active Dancers in Tension Control of Webs
With the need for increased performance and productivity in the web processing industry, accurate modeling and effective controller design for web handling systems is essential for increasing the web processing speed and the quality of the processed web. Accurate tension control has always been a key element of web handling systems. An important objective of the tension control system is to maintain tension within the desired limits under a wide range of dynamic conditions such as speed changes, variations in roll sizes, and web property. Tension variations affect printing quality and tend to cause web breakage and wrinkles. A dancer mechanism is typically used as a feedback element in a majority of tension control systems. The tension controller is driven by the variations in the position of the dancer mechanism as opposed to the variations in actual tension from the desired tension. The requirement to maintain the desired tension within a narrow range from the unwinding zone to the first printing unit places a demand for better design of the dancer mechanism. Disturbances arising from unevenly wound rolls and misalignment of the rolls have to be attenuated by the dancer mechanism, thus negating their propagation into the in-feed section. Currently, passive dancers are used as dancer mechanisms. Passive dancers have been known to act as a good tension feedback element for low speed web lines. Passive dancers have limitations in dealing with a wide range of dynamic conditions experienced in high speed web lines. It is expected that introducing an active element into a dancer mechanism gives a control engineer more flexibility in attenuating disturbances and also in maintaining lower tension fluctuations. In this project, modeling and control of active dancers leading to a better overall tension control systems will be explored.
Sponsor: Web Handling Research Center
PI: School of Mechanical and Aerospace Engineering: Prabhakar R. Pagilla
Web Transport Systems
The objectives of this research are (1) to expand the range of static and dynamic models in WTS to include models for new elements identified by sponsors; (2) to refine the models for viscoelastic effects and web-roller slip effects; (3) to develop new models for the precise control of tension in each section in a multi-span web transport system; and (4) to develop guidelines for selection of the control algorithms which best meet the defined performance objectives for a given application.
Sponsor: Web Handling Research Center
PI: Office of the Dean: Karl N. Reid
Lateral Control of a Web
Imperfections of thickness, flatness, and other properties of a web, as well as imperfections of web-handling machinery, cause the web to run off center of the process line, often resulting in damage to the web as well as waste. Automatic web guides are therefore commonly required for maintaining lateral alignment of the web. This analytical research is concentrating on prevention of wrinkles, oscillation, stretching of an edge, other potential problems which can result from guiding, and improvement of the accuracy of guiding.
Sponsor: Web Handling Research Center
PI: School of Mechanical and Aerospace Engineering: John J. Shelton