| 摘要 |
PURPOSE:To form a silica glass improved in breakage of the mold container during cooling by press forming the original silica glass in a mold container at high temperatures followed by moving the resultant form, within the identical container, to a cooling section differing in dimension from the former section to carry out annealing. CONSTITUTION:A molding container is made up of a molding section 44 with a specified inner surface shape and a cooling section 46 slightly differing in dimension from the section 44 with the both sections partitioned by a shoulder 48. That is, the sectional shape of a punch 14 to apply molding pressure from above corresponds to that of the upper section 44, while the sectional shape of a bearer 16 to that of the lower part of the cooling section 46. The resultant silica glass form produced in the section 44 is transferred to the section 46 by moving both the punch 14 and bearer 16 downward, and annealed in the section 46 with the contraction of a carbonaceous container 12 compensated by the dimensional difference. The displacement of the punch 14 and bearer 16 is measured using displacement gauges 50, 50. It is preferable that said punch 14 and bearer 16 be so designed as to control their displacements separately from each other. |
