| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a manufacturing method for a glass pipe for optical fibers, where the variation in its residual stress and its dimension can be prevented by drilling it under a constant viscosity, and to provide a manufacturing apparatus therefor. <P>SOLUTION: The pressure generated when a glass material 37 is penetrated with a drilling jig 48 is detected by a penetrating pressure detecting means 12. The state of softening of the glass material 37 can be judged by feeding back the detection signals of the means to a controlling device 11. Namely, when the penetrating pressure is small, the heating by a heating means 31 is weakened by a controlling means 11 to lower temperature so that the material is made less soft; on the other hand, when the penetrating pressure is large, the heating by the heating means 31 is strengthened by the controlling means 11 to raise temperature so that the material is made more soft. Thereby, the glass material 37 to be drilled can be drilled under a constant viscosity. <P>COPYRIGHT: (C)2003,JPO</p> |
