Patent ID: 8484997

Claim:
A method for producing a quartz glass cylinder, the method comprising: providing a porous SiO 2 body having a SiO 2 body wall defining a central inner bore with a lower end and an upper end; sintering the SiO 2 body in a sintering furnace zone by zone, starting from the upper end so as to obtain the quartz glass cylinder; holding the SiO 2 body with a holding device so that the SiO 2 body is held standing in vertical orientation during a first sintering phase and is suspended in a second sintering phase; wherein the holding device comprises a fusion body of quartz glass that, at the beginning of the first sintering phase, is positioned on a support ring that is supported on the SiO 2 body wall below the upper end of the inner bore, and wherein said fusion body during the first sintering phase fuses with quartz glass of the SiO 2 body and during the second sintering phase is in operative interaction with a holding element of the holding device and together with said holding element contributes to holding the SiO 2 body suspended during the second sintering phase.