| 摘要 |
The invention relates to a device and a process for producing a glass tube, preferably continuously. The device comprises a shaft ( 9 ) into which a glass melt is introduced, so that the outer profile of the glass tube ( 1 ) is determined at least in sections by the shaft, and a shaping means ( 10 ), which extends coaxially in the interior of the shaft, for determining the inner profile of the glass tube ( 1 ). The shaping means ( 10 ) is cooled and the shaft is disposed vertically. The glass melt is cast freely into the shaft ( 9 ) while forming a free meniscus. According to the invention, the shaping means ( 10 ) is cooled so that the glass melt solidifies in the shaft to form the glass tube ( 1 ). The glass passes through the temperature range which is critical for crystal formation within a very short time, so that precise glass tubes can also be produced from readily crystallising glasses. It is also possible to precisely shape glass tubes with any desired inner and/or outer profiles. Glass tubes with a comparatively low ratio of outside diameter (OD) to wall thickness (WT), in particular with a ratio OD/WT of lower than approximately 0.1*OD/[mm], can be produced by redrawing.
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