Patent ID: 11919794
Assignee: HERAEUS QUARZGLAS GMBH & CO. KG
Field: Other special machines (Mechanical engineering)
Classification: CPC C | IPC C

Claim 0:
1. A method of manufacturing a tube of quartz glass by molding a hollow cylinder having a hollow cylinder bore, an outer diameter Ca, an inner diameter Ci and a wall thickness which is at least 20 mm, by continuously feeding the hollow cylinder under rotation around a rotational axis into a heating zone at a relative feed rate VC, softening the hollow cylinder in areas in the heating zone, and radially expanding the softened area under the effect of a gas pressure applied in the hollow cylinder bore, and continuously molding a tube strand having an outer tube diameter Ta, a tube inner diameter Ti, and a tube wall thickness from the softened area and withdrawing the tube strand at a withdrawal speed VT,
wherein the gas pressure is an actuating variable of a diameter regulation and/or a diameter control for the tube outer diameter or for a geometrical parameter correlated with the tube outer diameter, and in that in a pressure build-up phase the gas pressure is gradually increased from a lower initial value to a higher final value characterized in that the gas pressure in the pressure build-up phase is increased at least temporarily with a temporal ramp Δp for which 0.01 mbar/min<Δp<0.8 mbar/min, and in that the following applies to the ratio of VC and VT:VT=VC±0.2·VC.