| 摘要 |
PURPOSE:To produce an optical glass element in high productivity at a low cost, by preforming a glass material heated at a specific temperature, and forming the preformed material. CONSTITUTION:The molten glass having a viscosity of 10<3>-10<8> poise and flowing out of the smelting furnace 1 through the pipe 3 is cut with the cutting edges 4, 5 to obtain a glass material 6. The material6 is placed on the lower mold 8 of a preforming mold, the rotary disk 7 is turned to position the lower mold 8 under the mold 11, and the upper mold 11 is lowered to press the material 6 and obtain a preformed glass 12. The glass 12 is taken out of the mold, inserted into a heating furnace 13, heated in vacuum or in an inert gas atmosphere at a temperature to get a glass having a viscosity of 10<13.6>-10<15> poise, placed on the lower mold of the main molding mold 14 and pressed by lowering the upper mold.
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