Web Handling Research Center

The Web Handling Research Center (WHRC) at OSU is one of 52 National Science Foundation Industry/University Cooperative Research Centers. The WHRC was initiated in 1986 and is the only center of its type in the world. The term "web" is used to describe materials that are manufactured and processed in a continuous, flexible strip form. Web materials cover a broad spectrum from extremely thin plastics to paper, textiles, metals, and composites. "Web handling" involves the physical mechanics related to the running and control of continuous strip materials (webs) through web processes and machines. A primary goal of web handling is to transport the material through processes and machines without incurring defects and losses. The mission of the WHRC is to advance the knowledge base in technologies applicable to the transport and control of continuous-strip materials through processes and machines. Fundamental and generic research studies are conducted in the following areas: mechanics of winding and unwinding, longitudinal dynamics and tension control, lateral dynamics and control, out-of-plane dynamics, wrinkling, measurement of tension and wound roll stress, and special topics (air films and conveyance, slitting, runability, and drying).

Sponsors: National Science Foundation, Oklahoma Center for the Advancement of Science and Technology, Oklahoma State Regents for Higher Education, U.S. Department of Energy, Noble Foundation, Beloit Corp., Dupont, Eastman Kodak, Fife Corp., Graphics Technology, Inc., Heidleberg Harris, Hoechst-Diafoil, ICI Americas, Kimberly Clark, Mead, 3M, Mobil Chemical, Norton, Polaroid, Reliance Electric, Rexham, Sonoco Products, Valmet-Appleton, and Worldwide Converting Machinery
PIs: Karl N. Reid and numerous faculty members indicated below

Air Entrainment with a Force-Loaded Nip Roller

Thin materials such as plastic films and paper are first made in the form of a roll before being converted into consumer products. When nonpermeable films including coated paper are wound at high speeds, excessive amounts of air can be trapped into the wound roll and make the roll defective. The most common method of reducing the entrapment of air in a winding roll is to use a nip roller which presses the winding roll and squeezes out the air moving with the film surfaces. The main objective of this study is to develop prediction equations for the amount of air entrapment in a winding roll pressed by a nip roller. A computer program has been developed and used to obtain prediction equations for the air entrapment for some idealized winding cases. The program is being further developed for faster calculation and for more realistic winding cases. Capabilities for experimental verification of the numerical computations continue to be developed.

Sponsor: WHRC
PIs: Frank W. Chambers, John J. Shelton, and Young Bae Chang (Mechanical and Aerospace Engineering)
RAs: Arif Akhtar and Peter Townes

The Control and Measurement of Web Rolling and Winding Air Films

The goal of this project is to develop models of the air films between moving webs and rollers or wound rolls and to use these models to develop means to control the various effects of the air films. Numerical computations of air films and pressures between moving webs and rollers have been performed. The two-dimensional code simultaneously solves the dynamic motion equation for the web and the Reynolds lubrication equation for the air film. The solution provides the spacing and pressure between the moving web and the stationary or moving roller as a function of both time and distance along the roller for the entire wrapped region. The effects of web and roller velocity, roller radius, slip flow, web tension, web mass per unit area, and web porosity are included. Additionally, air velocity profile measurements and flow visualizations have been performed to evaluate the effects of doctor blades on the air flow carried by rotating rollers. The results showed a very rapid redevelopment of the air layer downstream of the doctor blade.

Sponsor: WHRC
PI: Frank W. Chambers (Mechanical and Aerospace Engineering)
RAs: Gary B. Dewar and Satyanarayan S. Kothari

Air Jet Technology in Web Handling

During some manufacturing processes of thin materials, such as photographic films and magnetic media, the films must be handled without touching. Also, manufacturing of ultra-thin films requires special support and transport techniques because conventional roller supports can cause excessive stresses in the films. The goal of this study is to develop new techniques of non-contact handling of flexible materials. An experimental study on the impingement of air jets on a flat surface has been done. Experimental and computational studies of wall jets are underway. This study has various applications which include non-contact support of thin films, lateral positioning of thin films, spreading of wrinkled films, suppression of flutter, and automation of paper-making machines.

Sponsor: WHRC
PI: Young Bae Chang (Mechanical and Aerospace Engineering)
RAs: Misra Deepak and Robert McManis

Dynamic Instability and "Buzz" at Air Turn Bars

One of the serious problems in air-support devices is excessive local flutter of thin films, usually accompanied by a buzzing sound. The objectives of this study are to develop prediction equations for local flutter and buzz, and to develop design improvements for flutter-free operation of air-support devices. Our exploratory tests revealed that several different types of local flutter can occur. Each type is being investigated separately. Recently, local flutter of a thin film caused by an air flow in a diverging-flow geometry was tested and the flutter criterion was obtained.

Sponsor: WHRC
PIs: Peter M. Moretti and Young Bae Chang (Mechanical and Aerospace Engineering)
RA: Zhongdong Zhu

Out-of-Plane Dynamics of a Moving Web

Flutter of a moving web of paper due to drying air flows is a recurrent problem in high-speed paper machines, resulting in breaks of the paper and causing loss of production. The objectives of this project are to understand the dynamic behavior of a web running in an air flow, and to develop design improvements which will reduce flutter damage. Two different types of flutter mechanisms had been identified and the threshold conditions at which detrimental flutter occurs had been determined. A high-speed web machine is being designed for future flutter research. This new machine will enable us to perform flutter experiments on a meaningful scale and to study various aerodynamic effects in the fast-moving thin film.

Sponsor: WHRC
PIs: Peter M. Moretti and Young Bae Chang (Mechanical and Aerospace Engineering)

Measurements on Air Bar/Web Interaction for the Determination of Lateral Stability of a Web in Flotation Ovens

Air-support ovens are widely used for non-contact drying of coated films. One annoying problem in air-support ovens is the sideward motion of the floated film, which results in contact of the film with a wall and damage to the coating. The objectives of this study are to identify the aerodynamic forces which cause lateral displacement of a floated film and to develop a prediction method for the lateral position of the film in air-support ovens. A series of experiments had been done for measurements of the aerodynamic forces of commercial air bars. An analytical model of the aerodynamic forces had been developed. Also, an analytical model for prediction of the lateral position of a film in air-support ovens is being developed.

Sponsor: WHRC
PIs: Peter M. Moretti, John J. Shelton, and Young Bae Chang (Mechanical and Aerospace Engineering)
RA: Brigitte Busch

Sensing of Web Tension by Means of Roller Reaction Forces

Accurate control of tension in a moving web is necessary to minimize breakage of the web, as well as to maintain quality of coating, printing, and other processing. The accuracy of measurement of tension by conventional transducers has not been understood. This project will quantify the accuracy of measurement and will recommend changes in the configuration and operation of process lines for improvements in tension measurement and control.

Sponsor: WHRC
PI: John J. Shelton (Mechanical and Aerospace Engineering)