Patent ID: 8904825
Filing Date: 2014-12-09
Classification: C03B

Abstract:
1. A method of fabricating a glass rod from an elongated glass preform using a furnace, the furnace extending between an input end and an opposing output end, the glass rod being fabricated so as to have a target diameter, the glass preform having a region thereof extending in a longitudinal direction between a drawing start position and a drawing end position, the distance between the drawing start position and the drawing end position defining a length of the region, the glass preform having a pre-drawn diameter that varies over the length of the region from a first initial diameter value at the drawing start position to a second initial diameter value at the drawing end position, the method comprising: determining first and second drawing reference distance values respectively corresponding to the drawing start and drawing end positions, the first and second drawing reference distance values being dependent on the first and second initial diameter values, a predetermined feed speed value, and the target diameter, the first and second drawing reference distance values each being defined by the following equation: where: feeding the glass preform longitudinally into the input end of the furnace at a feed speed such that a plurality of points longitudinally spaced along the region pass the reference position of the furnace as the glass preform is fed into the furnace, the feed speed being maintained at the predetermined feed speed value; drawing the glass preform from the output end of the furnace at a variable drawing speed as the glass preform is fed into the furnace, the variable drawing speed being controlled so that as each point of the region passes the reference position of the furnace, the following equation is satisfied: wherein the drawing reference distance varies between the first and second drawing reference distance values over the length of the region, the variance of the drawing reference distance at each point of the region with respect to the first drawing reference distance value being based on the longitudinal location of the corresponding point within the region, wherein the drawing reference distance transitions linearly from the first drawing reference distance value at the drawing start position to the second drawing reference distance value at the drawing end position, and wherein the drawing reference distance at each point of the region is determined by interpolating between the first and second drawing reference distance values.