Encyclopedia of Glass Science, Technology, History, and Culture. Группа авторов. Читать онлайн. Newlib. NEWLIB.NET

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narrow slot, made of platinum, which is fixed at the bottom of the forehearth. The glass sheet pulled from the slot is then gripped on its edges to prevent narrowing (Figure 14). The suitability of this process for making thin glass stems from the fact that a viscous molten glass can be pulled downward with a higher speed than if it were just subjected to free fall [3, 7, 11].

      6.2 Fusion Downdraw

Schematic illustration of the slot downdraw process in cross section. The molten glass is pulled downward through a narrow slot driven by rolls. Schematic illustration of the fusion downdraw process in a bird's-eye perspective. Molten glass flows over weirs and run down on both sides of fusion pipe. Two glass streams join and merge together at the root and are stretched downward.

      Over the years the demand for flat glass has paralleled the growth of the global economy. In addition to architectural applications, the automotive, solar energy, and electronics especially flat panel display (FPD) application markets have all been at the same time growing and an important source of new, value‐added products (Chapter 6.10). Recently, glass sheets for chemically strengthened components such as cover glass for displays and ultrathin glass for touch panels have emerged as important products driven by the explosive diffusion of mobile phones and tablets with touch sensors [12]. These trends are supposed to continue and affect markets such as appliance, transportation, interior architecture, and many others. The important role of flat glass keeps increasing in these domains as well as in the field of information and communication, optics, healthcare, and so forth. Further improvements will thus be made to meet new specifications and respond to various market demands. From an industrial perspective, however, not only the cost and quality of the glass itself but also controllability, investment size, yield, delivery time, versatility, cost of post‐processing, and other factors of the manufacturing process have to be taken into consideration for each application. Therefore, an overall and comprehensive understanding of the forming process remains a key issue.

      Two directions for development of the forming process can be followed. One is to improve further currently existing processes in terms of flatness, thickness, width, productivity, controllability, cost, versatility, facility lifetime, etc. The other direction is to add values through online introduction of other features such as coating and surface treatment (cf. Chapters 6.7 and 6.8). A closer match and harmonization between forming process and glass composition and properties might be also attractive.

      As for forming commodity glass, invention of a novel process surpassing float with regard to energy consumption and investment costs would be desirable. For specialty glasses, innovative processes with higher quality and lower cost will of course also be sought after. Advances in basic science, simulation methods, sensing procedures, and information technology are presumed to become still more important either in operation and engineering or in development and innovation. Moreover, newly developed materials could make other innovative progress possible. In this respect, could unprecedented innovations based on novel mechanism make the processes described in this chapter obsolete in a near future? Their advantages should be considerable to write off the capital invested in current production plants all over the world. But would those innovations give rise to new applications and create new markets? A never ending challenge will change the world [15, 16].

      1 1 Cable, M. (2004). The development of flat glass manufacturing processes. Trans. Newcomen Soc. 74: 19–43.

      2 2 Yates, R.F. (May 1921). Revolutionizing the glass‐blowing industry. Popular Monthly: 30–32.

      3 3 Hynd, W.C. (1984). Flat glass manufacturing processes. In: Glass: Science and Technology, Vol. 2, Processing I (eds. D.R. Uhlmann and N.J. Kreidl), 45–106. New York: Academic Press, Inc.

      4 4 Yunker, R.W. (1984). Flat glass manufacturing processes, and C.K. Edge, Update. In: The Handbook of Glass Manufacture, 3rd ed., vol. 2 (ed. F.V. Tooley), 683–714 and p. 714/1–714/21. New York: Ashlee Publishing Co.

      5 5 Cable, M. (1999). Mechanization of glass manufacture. J. Am. Ceram. Soc. 82: 1093–1012.

      6 6 Mishima, Y. (1985). Flat glass forming, float process. In: Glass Encyclopedia [in Japanese] (ed. S. Sakka), 276–283. Tokyo: Asakura Shoten.

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