| 摘要 |
PURPOSE:To produce a core line of optical fiber having small variability of outer diameter efficiently, by coating the circumference of optical fiber with an ultraviolet-curing resin, and irradiating the resin with ultraviolet rays after cooling it or while cooling so that it is cured. CONSTITUTION:The optical fiber 1 consisting of a core and a clad, being pulled at a constant speed in the arrow direction A is provided with the ultraviolet- curing resin 3 from the resin storage tank 6 through the die 4 and coated. Then, the resin is cooled with air by the cooling chamber 7 connected to a part below the die 2. A cooling gas to be fed to the cooling chamber 7 is fed from the blow inlet 8 shown by the arrow B while being controlled to a desired temperature and amount, and exhausted from the outlets 9 and 10 shown by the arrows C and D. The viscosity of the ultraviolet-curing resin 3 is raised by this cooling, drop of the resin 3 by its own weight is prevented. The resin is irradiated with ultraviolet rays by the ultraviolet lamp 4, and the resin 3 is cured. An ozone gas occurring during the curing is exhausted from the outlets 9 and 10.
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