Читать книгу Encyclopedia of Glass Science, Technology, History, and Culture - Группа авторов - Страница 93

At the same time the Fourcault process was being developed, the American inventor I. W. Colburn (1861–1917) was experimenting vertical drawing without a débiteuse. His first patent was taken in 1902 but the company he founded in 1906 to produce glass went bankrupt five years later. Working thereafter for the Toledo Glass Company, which had bought his patent, Colby was eventually successful in 1913. With his process, the molten glass introduced into a shallow drawing chamber was drawn upward from the free surface, its edges being gripped and driven by pairs of knurled rolls, and cooled immediately. After being reheated by a gas burner, the formed glass was brought horizontally by a bending roll and conveyed to a horizontal annealing lehr (Figure 3). Since the surface condition and flatness of the bending roll directly determined the quality of the glass sheet, the choice of an appropriate metal as well as the surface treatment and temperature control of the bending roll were crucial. Typically, two drawing chambers were mounted on one glass tank. The 0.9–6 mm thickness range obtained was similar to that of the Fourcault process, but devitrification on the débiteuse was avoided and a much larger width of up to 4.2 m could be obtained, thanks to the horizontally conveying process. But the price to be paid was a lower glass quality because of thickness variations, optical distortions, and surface defects [1, 3–6].

Figure 3 Sketch of Colburn process in a bird's‐eye perspective. The molten glass is drawn upward from the free surface and bended horizontally by a bending roll [6].