| 摘要 |
PURPOSE:To reduce the breakage of a reaction tube and to improve the productivity of a glass preform by providing a mechanism for travel and position of a heater and a control means for moving the heater moved to the downstream side stepwise to the upstream side. CONSTITUTION:A reaction tube 1 of quartz glass, etc., is held by a rotating supporting part 2 and rotated. The gaseous glass starting material such as silicon tetrachloride and boron trichloride, and oxygen respectively from their sources are supplied into the reaction tube 1 from its one end, the reaction tube 1 is externally heated by a heater 3 such as a heating burner fixed to a pedestal 5 provided with a motor 4 and capable of being reciprocated in axial direction of the reaction tube 1, and hence soot as the oxidation product of the raw gas in the reaction tube 1 is deposited on the inner wall of the tube, heated and melted to form a glass layer. Meanwhile, the gases after reaction are treated by a scrubber furnished on the upstream side of the reaction tube 1. |
