Improvement of Web Spacing and Friction Characteristics by Two Types of Stationary Guides
Author:
Hashimoto Hiromu1, Nakagawa Haruyasu2
Affiliation:
1. Department of Mechanical Engineering, School of Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa, 259-1292, Japan 2. Graduate School of Engineering, Tokai University, 1117 Kitakaname, Hiratsuka, Kanagawa, 259-1292, Japan
Abstract
In this paper, two types of stationary guides are presented to improve the web spacing characteristics; hybrid hollow porous guide for maintaining the sufficient web spacing and grooved guide for removing the entrained air. In the hybrid hollow porous guide, the pressurized air is added to the lubrication air flow between web and guide from inside the guide. Then, the web spacing characteristics are improved by the hybrid effects of hydrodynamic pressure due to web movements and hydrostatic pressure due to pressurized added air through the guide. The relations between web spacing and web velocity are measured under various supply pressures. Moreover, the relations between web spacing and web tension are examined. The contactless optical sensor, which can measure the variation of the quantities of reflected light from the back surface of web according to the variation of web spacing, is used to obtain the web spacing under various conditions. In the grooved guide, the method for the estimation of web spacing by using the concept of equivalent spacing between web and guide is presented, and the web spacing is measured by the same experimental apparatus used in the case of hollow porous guide. From the calculated and measured results obtained, the effectiveness of two types of guides on the web spacing is clarified. Finally, based on the assumptions of Gaussian distributions of asperities, the simple relations to predict the friction coefficient between web and guide surfaces are formulated, and the variation of friction coefficient with velocity is shown for various values of web tension.
Publisher
ASME International
Subject
Surfaces, Coatings and Films,Surfaces and Interfaces,Mechanical Engineering,Mechanics of Materials
Reference19 articles.
1. Hashimoto, H.
, 1999, “Air Film Thickness Estimation in Web Handling Processes,” ASME J. Tribol., 121, No. 1, pp. 50–55. 2. Hashimoto, H.
, 1995, “Theoretical Analysis of Externally Pressurized Porous Foil Bearings—Part I: In the Case of Smooth Surface Porous Shaft,” ASME J. Tribol., 117, No. 1, pp. 103–111. 3. Wildmann, M., and Wright, A., 1965, “The Effect of External Pressurization on Self-Acting Foil Bearings,” ASME J. Basic Eng., 87, pp. 631–640. 4. Barlow, E. J., and Wildmann, M., 1968, “The Axisymmetric, Perfectly Flexible Foil Bearings with Porous Inlet Restrictor,” ASME J. Lubr. Technol., 90, No. 1, pp. 145–152. 5. Baumann, G. W.
, 1971, “Analysis of a Porous Gas Foil Bearing,” ASME J. Lubr. Technol., 93, No. 3, pp. 456–464.
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