| 摘要 |
<p>PURPOSE: To enable the production of quartz glass of an increased size in a low cost by uniformly preparing a tapering over a heat-resistant base rod of a large size and keeping the tapered rod perpendicularly so that its larger diameter part comes lower after a porous quartz preform is formed around the rod and vitrifying the preform with heat. CONSTITUTION: A cylinder or cylindrical tube shape heat-resistant base material 1 having its outer diameter of 20-500mm and its length of 500-5,000mm is provided with a substantially uniform tapering (α). This base rod 1 is rotated as fine particles of quartz glass are blown to its outer surface to form a porous quartz glass preform material 3. Then, the rod 1 with the preform material 3 is held perpendicularly so that its larger diameter part comes lower and is vitrified by the zone-melting method from the bottom up to the top to give the objective quartz glass 4. When the heat-resistance base rod 1 or a heat- resistant molded product 2 is a quartz glass rod or tube, a quartz glass ingot is obtained, and, when the tube or rod is the other substance, it is pulled off after vitrification to give a quartz glass tube.</p> |
