Patent · US Expired

Method of improving the geometrical shape of a tube used for making a preform by selectively etching the bore of the tube

US5676724A · kind A · utility

6Cited by
6References
3Claims
0Family size

Assignee

Inventors

Key dates

Filing dateOct 17, 1995
Grant dateOct 14, 1997
Priority date—
Expiry dateOct 17, 2015

Classification

  • Technology area (CPC C)Chemistry; Metallurgy
  • CPC primaryC03B37/01228
  • WIPO fieldMaterials, metallurgy
  • WIPO sectorChemistry

Abstract

A method of improving the symmetry of a cylindrical silica tube to be used in making a preform having a circular outside surface eccentric to a circular inside surface thereby providing a varying tube thickness throughout the circumference of the tube which includes the following steps. The first step is locating a longitudinal generator line of the cylindrical tube at a greatest thickness of the tube at a given circumferential point on the tube, and while preventing the tube from rotating, etching in at least one pass the inside of the tube with a gas capable of decomposing silica, while heating the outside of the tube along that longitudinal generator line.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.