US 6,438,997 B1 · Method of elongating glass preform

Abstract

In a method of elongating a glass preform comprising the steps of holding both ends of the glass preform 1a with a first holding section 2 and a second holding section 3, respectively; moving the first holding section 2 and the second holding section 3 in a longitudinal direction of the glass preform 1a with the moving speed of the first holding section 2 faster than that of the second holding section 3 and, at the same time, heating and softening the glass preform 1a by a heating section 4 successively; and elongating the glass preform 1a by a tensile force applied thereto, so as to form an elongated body 1c; an electric furnace is employed in the heating section 4; and said method further comprising the steps of setting a reference value R1 with respect to an outside diameter at a specific position 1d in a tapered region 1b in the glass preform 1a in the process of elongating; acquiring an actually measured value R2 at the specific position 1d; and controlling the moving speed of the first holding section 2 and/or second holding section 3 according to a value (R2/R1) obtained from the reference value R1 and actually measured value R2.

Claims10

Dependent claims

A method of elongating a glass preform comprising the steps of holding both ends of the glass preform with first and second holding sections, respectively;

moving the first and second holding sections in a longitudinal direction of the glass preform with the moving speed of the first holding section faster than that of the second holding section;
heating and softening the glass preform by a heating section successively from the end portion on the first holding section side as the first and second holding sections move in the longitudinal direction of the glass preform;
and elongating the glass preform by a tensile force applied to the glass preform;
wherein an electric furnace is employed in said heating section, and said method further comprising the steps of:
setting a reference value R1 with respect to an outside diameter at a specific position in a tapered region of the glass preform in the process of elongating;
acquiring an actually measured value R2 which is an outside diameter at said specific position;
and
controlling the moving speeds of said first holding section and/or second holding section according to a value (R2/R1) obtained from said reference value R1 and actually measured value R2.

5 more elements

A method of elongating a glass preform comprising the steps of holding both ends of the glass preform with first and second holding sections, respectively;

moving the first and second holding sections in a longitudinal direction of the glass preform with the moving speed of the first holding section faster than that of the second holding section;
heating and softening the glass preform by a heating section successively from the end portion on the first holding section side as the first and second holding sections move in the longitudinal direction of the glass preform;
and elongating the glass preform by a tensile force applied to the glass preform;
wherein an electric furnace is employed in said heating section;
and said method,further comprising the steps of:
setting a reference value R1 with respect to an outside diameter, at a specific position, of a tapered region in the glass preform in the process of elongating;
acquiring an actually measured value R2 which is an outside diameter at said specific position;
and
controlling the moving speeds of said first holding section and/or second holding section according to a value [(R2/R1)−1] obtained from said reference value R1 and actually measured value R2.

6 more elements

Dependencies are inferred from the claim text.

Method of elongating glass preform

Life of this patent

Method of elongating glass preform

Life of this patent

Abstract

Claims10