| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to improve workability and to reduce a cost without the generation of soot, to position a preform with respect to a heater with simple constitution, to make the temp. at the circumference of the molten part of the preform uniform and to lessen the fluctuation in the outside diameter of the optical fiber. SOLUTION: A heating furnace 3 for heating and melting the preform 1 is provided with the heater 13 formed by embedding electric heating wires in a thermal conductor 43 made of aluminum. The positioning of the preform 1 with respect to the heater 13 is executed by passing the preform 1 into the positioning hole 65 of a positioning member 7 at the time of inserting the preform 1 into the heating furnace 3 by a preform feeder 5. Air is injected from an introducing pipe 73 in the direction inclined by a prescribed angle in the circumferential direction of the preform 1 from the downward direction of the perpendicular direction and the air on the circumference of the preform 1 is effectively disturbed not only in a vertical direction but in a circumferential direction as well. |
