| 摘要 |
PURPOSE:To control to reduce elongation of a filament by making the descending speed of a bottom electrode and filament temperature freely controllable, and making the descending speed greater than the speed of thermal expansion of the filament. CONSTITUTION:In a tube inside coating unit that applies tension to a filament 4 inserted in a tube 2 by an electrode 6 provided below the filament and, at the same time, raise the temperature to the evaporation temperature by heating electrically, a balancing weight 12 is installed to the electrode 6 through a rope 11. Further, a driving device 13 is installed to the balancing weight 12 through a rope 14. The descending speed of the electrode 6 is controlled by the balancing weight 12 and the driving device 13. When the speed of temperature rise of the filament 4 is fast, the speed of thermal expansion exceeds the descending speed of the electrode 6 and the filament 4 becomes loose in the tube 4. Then, the temperature of the filament 4 and the descending speed of the electrode 6 are controlled by a control unit 18 basing on detected values from a filament temperature detector 19 and a descending speed detector 20. |
