APPARATUS FOR COOLING OPTICAL FIBER AND COOLING METHOD

摘要

PURPOSE:To achieve sufficient cooling effect even in high-speed drawing and to obtain a coated fiber having stable diameter by varying the cooling length of an optical fiber cooling apparatus according to the linear speed of the optical fiber to be drawn. CONSTITUTION:A cooling apparatus 40 for forcedly cooling an optical fiber 9 is placed between a drawing furnace 2 to draw an optical fiber preform 1 under heating and melting and a resin coater 5 to coat the drawn optical fiber 9 with a resin. The main body 41 of the cooling cylinder of the cooling apparatus 40 is provided with an extension cylinder 42 which is vertically slidable relative to the main body 41. The cooling length is made to be variable by moving the extension cylinder 42 above or below with a cooling length controlling means according to the linear velocity of the fiber. The cooling length is adjusted to a proper level corresponding to the linear velocity. The optical fiber 9 is cooled by introducing cooling water 12 into spaces between the inner cylinder 41a and the outer cylinder 41b of the main body 41 and between the inner cylinder 42a and the outer cylinder 42b of the extension cylinder 42 and blowing cooling gas 11 into the inner cylinders 41a, 42a.