| 摘要 |
PURPOSE:To obtain rodlike phase-separated glass free from striae by shifting refined agitated molten starting material for glass to a pulling furnace, bringing the lower end of a pulling rod into contact with the surface of the resulting molten glass adjusted to a specified temp., and pulling up the rod. CONSTITUTION:Starting material 17 for glass is put in crucible 15, and it is melted and agitated with agitating rod 16 while keeping crucible 15 at 1,400-1,550 deg.C in melting furnace 11. The temp. is then dropped to 1,150-1,350 deg.C, molten material 17 in crucible 15 is refined and agitated with agitating rod 16, and rod 16 is pulled up from crucible 15. Crucible 15 is immediately shifted to pulling furnace 18 kept at 900-1,100 deg.C, and after adjusting molten glass 21 in crucible 15 to 900-1,100 deg.C, the lower end of pulling rod 22 is brought into contact with the surface of glass 21. While pulling up rod 22, rodlike glass in cooled. |
