Method and apparatus for drawing a quartz glass strand

US9242887B2 · kind B2 · utility

Assignee

• HERAEUS QUARZGLAS GMBH & CO. KG · DE

Inventors

• Boris Gromann · Aschaffenburg, DE
• Christian Neumann · Hungen, DE

Key dates

• Filing date: Jan 26, 2012
• Grant date: Jan 26, 2016
• Expiry date: Sep 23, 2032

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C03B17/04
• WIPO field: Other special machines
• WIPO sector: Mechanical engineering

Abstract

In a known process for drawing a quartz glass strand, SiO2 particles are fed to a melting crucible and softened therein to form a quartz glass mass, and the softened quartz glass mass is pulled vertically downward as a quartz glass strand via a drawing nozzle which is provided in the bottom region of the melting crucible and has a gap-like drawing nozzle opening. In order, on the basis thereof, to make it easier to reproducibly produce a quartz glass strand with a minor deviation from the nominal wall thickness profile, and in particular to avoid irregularly occurring indentations and protrusions of the wall thickness profile, it is proposed according to the invention that the wall thickness profile of the quartz glass strand is detected, and that the drawing nozzle is heated by means of a plurality of heating elements which are distributed around the drawing nozzle opening and can be electrically actuated independently of one another, and that the quartz glass mass is locally heated by means of the heating elements within the gap-like drawing nozzle opening depending on measurement results of the wall thickness profile.