Abstract: A glass composition to be softened is fed to a heating zone and is shaped continuously into a cylindrical component in a deformation zone, and the cross-sectional geometry of the component is determined. A feed device, a heating device, and a take-off device are provided, and a glass composition is supplied continuously by the feed device to the heating device, where it is softened, the component being formed from the softened glass composition by means of the take-off device under formation of a deformation zone. To produce a component with only slight deviations from the desired cross-sectional geometry and to provide a flexible apparatus suitable for this purpose, the glass composition is locally heated or cooled in at least one deformation area, which extends over only a part of the circumference of the deformation zone, as a function of a determined deviation of the cross-sectional geometry from a nominal geometry.

Abstract: In a known method for the manufacture of a tube made of a vitreous material, especially of quartz glass, a hollow cylindrical semifinished product made of a vitreous material is carried essentially vertically to a heating zone, wherein it is heated and drawn off downwards—without the use of tools—to the tube by forming a transitional area from semifinished product to tube, while diameter and wall thickness of the tube are continuously measured, and the tube's measured geometrical data being used to generate a control signal with the aid of which a pressure difference is regulated between pressure P1 in the interior space of the semifinished product, the transitional area and the tube, as well as pressure P2 in the heating chamber which is regulated in the heating zone at least in the transitional area from semifinished product to tube and its adjacent tube area.