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

Автор: Группа авторов
Издательство: John Wiley & Sons Limited
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Жанр произведения: Техническая литература
Год издания: 0
isbn: 9781118799499
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Float process For thinner sheet (Top roll process) Viscous flow with equilibrium thickness in upstream area of bath Horizontally stretching by conveyor rolls and top rolls Large‐scale production (productivity) Quality (flatness) Flexibility for thickness and width Large investment Constraint of chemical elements in glass Widely operating in the world for various applications For thicker sheet(Fender process) Viscous flow with restricted width by pair of fenders Cooling to appropriate temperature in fender area (without stretching) + Thicker and larger sheet Downdraw process Slot downdraw process Glass flow toward slot and downward flow through slot Stretching by pairs of rolls and gravity with anchored to slot Thinner glass Small‐scale production Flatness and surface quality Limited width Customized/modified process operating for specialty glass Fusion downdraw process Glass flow through trough and over weirs, downward flow on both sides of fusion pipe Stretching by pairs of rolls and gravity with anchored to root Thinner glass High surface quality Minute control required (temperature, glass flow) Constraint of liquidus viscosity Popular for specialty glass

      3.1 Fourcault

      The advantages of this process were many. Not only could production be made with several drawing machines for a single glass tank, but wide ranges of thickness (1–8 mm) and width (1.5–2.5 m) were possible for glass sheets formed with a relatively uniform thickness. In terms of disadvantages, continuous operation was impossible because of the need after about two weeks of operation to remove the devitrified glass that was accumulating around the slot of the débiteuse and on the inner surfaces of the drawing kiln. Whereas the former devitrified material was causing draw lines, the latter changed the flow rate and flow pattern toward the débiteuse. In addition, it was impossible to maintain a completely stable throughput because of bubble formation at the beginning of a drawing cycle and draw‐line problems and instability toward the end [1, 3–6].

Schematic illustration of the Fourcault process in cross section. The molten glass flows up through the débiteuse slot and is drawn upward.

      3.2 Colburn

      3.3 Pittsburg Pennvernon

      3.4 Asahi