Method of producing an elongated glass body, particularly a preform for optical waveguides

  • US 4,867,774 A
  • Filed: 09/25/1987
  • Issued: 09/19/1989
  • Est. Priority Date: 05/21/1985
  • Status: Expired due to Fees
First Claim
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1. A method of producing an elongated glass body for use as a preform for SiO2 -base optical waveguides wherein a porous body is initially formed from a glass powder material and then sintered to form the glass body, said method comprising the steps of:

  • providing a supply vessel for glass powder material, said supply vessel including a tube extending therefrom, and a conveying means for conveying glass powder material from said vessel through said tube;

    inserting said tube from said supply vessel into a first end of a rigid, hollow elongated mold, said tube having an open portion from which glass powder material is discharged into said mold and said tube and mold exhibiting selective relative motion along the lengths thereof, thereby enabling said mold to be displaced with respect to said tube as said mold receives glass powder material;

    covering a second end of said mold with cover means for covering said second end of said mold;

    applying a longitudinal force against the cover means so that the force acts upon the cover means and mold in a direction towards the first end;

    conveying glass powder material from said supply vessel through said tube, said conveying means subjecting said glass powder material to a continuous filling pressure as said glass powder material is conveyed through said tube;

    discharging glass powder material from said open portion of said tube into said mold thereby displacing said mold in a direction opposite to that of said longitudinal force applied to said cover means with respect to said tube as filling pressure on said glass powder material at said open portion of said tube acts against the longitudinal force applied to said cover means, whereby the glass powder material is compacted as it is discharged from the tube;

    consolidating said compacted glass powder material within said mold by heat treating to form a porous body; and

    sintering the porous body to form the glass body.

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