Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 92

The first manufacturing method successfully industrialized and commercialized was invented from 1901 in Belgium by É. Gobbe and É. Fourcault and finally implemented industrially in 1912 by É. Fourcault in his family company in Charleroi. With this process, the molten glass was drawn vertically through a débiteuse into a continuous glass ribbon. The débiteuse, a rectangular refractory piece with a spindle‐shaped slot at the center, was immersed into the molten glass. The molten glass flowing up from the slot was drawn upward and immediately cooled by the coolers while conveyed upward by pairs of rolls in a such a manner that its width was kept constant. The formed glass was annealed along the way and finally cut off at the top of the 8–10 m drawing tower (Figure 2). The flow rate was controlled by the immersion depth of the débiteuse, the shape of the slot, and the cooling exerted, whereas the thickness of the sheet was determined by the drawing speed.

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].

Figure 2 Sketch of Fourcault process in cross section. The molten glass flows up through the débiteuse slot and is drawn upward [3].