Patent ID: 8393179

Claim:
A method for producing a semifinished product of synthetic quartz glass by plastic deformation of a softened SiO 2 mass in a melt mold, said method comprising the following steps: (a) providing a porous SiO 2 soot body, (b) zonewise sintering of the SiO 2 soot body in the melt mold at a sintering temperature and during a sintering period so as to form a completely sintered transparent quartz glass body, and (c) shaping the sintered quartz glass body by softening the sintered quartz glass body in the melt mold so as to form a viscous quartz glass mass that fills the volume of the melt mold entirely or partly, and (d) cooling the quartz glass mass and removing the mass from the melt mold so as to form the semifinished product; and wherein the sintering starts from a top of the soot body and proceeds downwards, and the shaping starts from a bottom of the sintered quartz glass body and proceeds upwards.