Heraeus-schott Quarzschmelze Gmbh

Herbert Schul

Tubes of transparent, translucent or opaque fused silica are made by heating a hollow cylindrical blank in a drawing zone, drawing the blank from the zone while maintaining its interior under pressure and rotating same about its longitudinal axis, and calibrating the still-plastic tube immediately upon leaving the drawing zone in a calibration zone defined by two graphite plates. Apparatus for carrying out the method includes means for heating the blank to a drawing temperature in a drawing zone, means for drawing the blank from the zone, means for maintaining the interior of the blank under pressure and means for rotating the blank as it is drawn, and calibrating means for calibrating the still-plastic tube immediately upon leaving the drawing zone including two graphite plate means disposed on metal plates through which a coolant can flow.

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Hanau am Main, Germany

Herbert Schul