| 摘要 |
PURPOSE:To obtain a uniform tube diameter by winding a heated glass tube and almost simultaneously injecting the inert gas in multiple stages with the pressure increased in sequence. CONSTITUTION:The inert gas such as nitrogen fed from a gas bottle is set to respective pressures of the first-third stages by a regulator valve 1. According to the experiment, 0.2-0.4kg/cm<2> is preferable for the set pressure of the first stage, 0.5-1kg/cm<2> for the second stage, and 1-2kg/cm<2> for the third stage. Solenoid valves 2 are operated upon receiving signals from a timing controller or the like, the valve 2 of the first stage is opened almost concurrently with the winding, the valve 2 of the second stage is opened about 0.5-0.7sec after the start of the winding, and the valve 2 of the third stage is opened 0.7-1.0sec after the start of the winding to inject the inert gas. After all valves 2 are closed and the winding is completed, a solenoid valve 3 is opened, and the pressure in an injection circuit is reduced to the pressure near the atmospheric pressure. Accordingly, a nearly uniform tube diameter can be obtained at portions where the winding is started and completed.
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