| 摘要 |
PURPOSE:To prevent generation of contraction and large diameter part, etc., by determining a deviation of measured value of outside diameter of a parent material for optical fiber during drawing from a referential value, and percentage of change of the outside diameter, and controlling drawing speed and heat amt. for a heating means, etc., basing on the determined values. CONSTITUTION:Both ends of a parent material 6 for optical fiber are held by each revolvable chuck 8, 10 on a stationary main shaft base 2 and a movable main shaft base 4, and a tension is given to the parent material 6 while revolving the material in the axial direction. Simultaneously, the parent material 6 is drawn by heating a part of the parent material 6 with a burner 16. In this stage, the outside diameter of the parent material 6 during drawing or just after drawing is measured with an outside diameter measuring device 14a, 14b, and deviation is determined from the measured values and a referential value stored in an operation controller 24, and precentages of the change of the outside diameter is also determined. The outside diameter of the parent material after drawing is made uniform by controlling the drawing speed of the parent material 6 basing on the deviation and controlling at least one of the heat amt. of the burner 16 or feed speed of the burner relative to the parent material basing on the percentage of change of outside diameter. |
