Spacing Characteristics Between Moving Permeable Web and Roller

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In the manufacturing fields of plastic sheet, paper, magnetic tape, photographic film etc., these continuous flexible materials are generally called "web", and the web transporting systems supported by the guide rollers are often used. Moreover, in addition to the transporting processes, the web winding processes are included in the systems. In such systems, it is of cardinal importance to estimate an entrained air film thickness (lubricating air film thickness) between web and guide roller or between layers in the wound web for better understanding the fictional conditions and for improving the efficiently of web handling processes. The air film thickness formula based on the infinitely long width foil bearing theory is usually used for the estimation of entrained air film thickness in the web handling processes. However, in the case of small web width, the infinitely long bearing assumption will cause some quantitative errors in the estimation of air film thickness. Therefore, it has … More been required for more accurate estimation of air film thickness to take into account the effects of web width. For such a requirement, Hashimoto obtained recently the convenient simplified formula for the estimation of entrained air film thickness between web and roller, which includes the web width, web tension and web velocity as parameters, based on the numerical solutions of compressible Reynolds equation and web elastic equation. However, as far as the authors know, there is no published paper examining experimentally the effects of web width on the entrained air film thickness between web and roller.In this research work, the effects of web width on the entrained air film thickness between web and guide roller were examined experimentally. The narrow width of audio-tape and the relatively wide width of paper were used as web in the measurements of air film thickness and two types of test rigs were used for each case. The air film thickness was measured for various combinations of velocity and web tension. The measured results were compared with the calculated results based on the simplified formula derived by Hashimoto and the effects of web width on the air film thickness were examined theoretically and experimentally. Less