The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 24, 2006
Filed:
Feb. 12, 2004
Tatsuhiko Saitoh, Kanagawa, JP;
Tatsuhiko Saitoh, Kanagawa, JP;
Sumitomo Electric Industries, Ltd., Osaka, JP;
Abstract
The present invention provides a method of elongating a glass preform having holes extending in the longitudinal direction while suppressing excess shrinkage of the holes. In the method of elongating a glass preform of the present invention, both ends of the glass preform having the holes extending in the longitudinal direction are held by a first holding member and a second holding member, respectively; and the glass preform is successively heat-melted from one of the ends by a heating means while the distance between the first holding member and the second holding member is increased in the longitudinal direction, to elongate the glass preform. The glass preform is elongated by heat-melting with the heating means in a manner such that the temperature T of the softened portion satisfies a relation represented by 11[° C./mm]·D+860[° C.]<T<17[° C./mm]·D+880[° C.], where D is the outer diameter of a post-elongation glass preform, and T is the maximum temperature of a softened portion of the glass preform heat-melted by the heating means.