To prevent cores from floating when the cores are wetted with wetting resin in order to infiltrate ultraviolet curing resin to the circumference of a plurality of the cores intertwisted on the outer periphery of the central tension wire in the manufacture of an optical fiber unit.
In the method for producing the optical fiber unit, the plurality of the cores 4 are intertwisted around a central tensile wire 2, are wetted with wetting resin 6 and are then sent into a core collecting part 8. An integration material which consists of ultraviolet curing resin 10 is applied by using a UV resin coater on the cores 4. The resultant coated optical fibers are sent to an ultraviolet irradiation device 12, and ultraviolet rays are radiated to cure the integration material. Delivery tension of the cores 4 at the time the cores 4 are sent into the coated fiber collecting part 8 is set to 50 g or more and 100 g or less.
SHIMOMICHI TAKESHI
OHASHI KEIJI
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