| 摘要 |
PROBLEM TO BE SOLVED: To control a drawing apparatus for drawing a glass preform so that a drawn body having a high accuracy outer diameter can be obtained very quickly and stably. SOLUTION: When the drawn body 28 having a prescribed outer diameter is obtained by taking up the drawn body from the front side in the feeding direction while feeding the glass preform 22 into a heating furnace 23 so as to heat and soften the glass preform 22, the outer diameter of the diameter reduced part 22a of the glass preform 22 on the way of drawing is measured at a prescribed position, and the final drawn outer diameter Ds of the drawn body 28 is controlled based on the difference between the measured outer diameter D1 and a predetermined target outer diameter R1 at the prescribed position. The final drawn outer diameter Ds of the drawn body 28 is controlled by measuring outer diameters at three positions in the axis direction of the a diameter reduced part 22a of the glass preform 22 as the taper shape of the diameter reduced part 22a, then determining an estimated drawing outer diameter s, obtained by estimating the outer diameter of the drawn body 28 being taken out, based on the measured results and a previously calculated model of the taper shape of the diameter reduced part 22a, and previously correcting the predetermined target outer diameter R1 according to the estimated drawing outer diameter. COPYRIGHT: (C)2004,JPO&NCIPI
|
