High optical quality glass tubing and method of making

Patent metadata

Field	Value
Publication number	US-10450214-B2
Application number	US-201715584357-A
Country	US
Kind code	B2
Filing date	May 2, 2017
Priority date	Jun 10, 2016
Publication date	Oct 22, 2019
Grant date	Oct 22, 2019

Abstract

A laminated or single layer glass cylinder and its method of making are disclosed. The laminated cylinder glass is a precursor component to enable making subsequent drawn tubing having high optical quality. The laminated cylinder glass may comprise a first layer of glass as a clad glass and a second layer of glass as a core glass. The second layer of glass may be bound to the first layer of glass. The second layer may have a higher CTE from about 5×10−7/° C. to about 100×10−7/° C. than the first layer of glass. The first layer and second layer of glass may have different softening points within about 200° C. of each other. In some embodiments, the first layer and second layer of glass may have different softening points from about 50° C. to about 200° C. of each other.

First claim

What is claimed is:

1. A method for producing a high optical quality hollow cylinder of glass tubing, comprising:
rotating a substantially elongated tubular mold having a substantially open end at one side, a substantially closed end at another side, and a cylindrical casting chamber between the substantially open end and the substantially closed end, the substantially elongated tubular mold being rotated along an elongated axis passing through the open end and the closed end;
heating at least a portion of the substantially elongated tubular mold at or above a strain point temperature (η=10 14.5 P) of the glass from which the glass tubing is formed;
delivering molten glass via stream or gob through the substantially open end into the cylindrical casting chamber while rotating the substantially elongated tubular mold;
tilting the substantially elongated tubular mold to a substantially horizontal position while rotating the substantially elongated tubular mold;

rotating the substantially elongated tubular mold on a generally horizontal axis;
causing molten glass to assume a form of a cylindrical tube in response to the rotation of the mold; and
cooling the cylindrical tube of glass to be quenched to form a first glass cylinder within a range including solidified, isoviscous or semi-solidified states.

2. The method of claim 1 , wherein the substantially elongated tubular mold is made of at least one of graphite, ceramics, inconel, platinum or combinations thereof.

3. The method of claim 1 , further comprising cleaning the first glass cylinder by water or acid etching or both, or grinding and polishing outer surfaces of the first glass cylinder to obtain a good surface condition with consistent wall thickness.

4. The method of claim 1 , wherein the substantially elongated tubular mold comprises an inner flange adjacent to the open end of the substantially elongated tubular mold to keep the cylindrical tube of glass from flowing out of the substantially elongated tubular mold.

5. The method of claim 1 , further comprising redrawing the first cylinder of glass by feeding the first cylinder of glass into a down feed system at a feed rate v f from about 0.2 mm/min to about 100 mm/min to a heating zone with a heating zone temperature T h from about 300° C. to about 1500° C. corresponding to a viscosity range from about 10 4 P to about 10 7 P.

6. The method of claim 5 , further comprising softening the first cylinder of glass in the heating zone so as to form a softened region.

7. The method of claim 6 , further comprising drawing off a component strand in a direction of a drawing axis from the softened region so as to elongate and reduce the size of the cylindrical tube to form various diameter sizes of a cylindrical tube of glass and at a drawing rate v d from about 0.01 m/min to about 100 m/min, wherein the drawing rate, viscosity of glass, and downfeed rate control the various diameter sizes of the cylindrical tube.

8. The method of claim 7 , wherein the various diameter sizes of the cylindrical tube have diminished roughness on the surface, wherein the rms roughness of the inside surface of the cylindrical tube is from about 5 nanometers to about 20 nanometers.

9. The method of claim 1 , wherein the rotating rate is from about 50 rpm to about 750 rpm.

10. The method of claim 1 , wherein the cylindrical casting chamber has a taper from the substantially closed end to the substantially open end so as to ensure a release of the cylindrical tube.

11. The method of claim 1 , further comprising delivering a second glass of different composition from the first into the mold inside the first glass cylinder and spinning to make a second concentric cylinder inside the first.

12. The method of claim 11 , further comprising delivering a third glass of the same or different composition from first into the mold inside the second glass cylinder and spinning to make a third concentric cylinder inside the first and second, wherein the glass composition of the second and the third glass have different coefficients of thermal expansion.

13. The method of claim 12 , wherein each of the first and the third CTE is from about 20×10 −7 /° C. to about 100×10 −7 /° C., and the second CTE is from about 25×10 −7 /° C. to about 120×10 −7 /° C.

14. The method of claim 11 , wherein the glass composition of the first and the second glass have different coefficient of thermal expansion (CTE).

15. The method of claim 11 further comprising removing or reducing one or more layers of glass via etching mechanical means.

Assignees

• Corning Inc

Inventors

• Mcenroe David John
• Palumbo Aniello Mario

Classifications

• C03B17/025

  Tubes or rods · CPC title

• C03B19/04

  by centrifuging {(C03B19/095 takes precedence)} · CPC title

• C03B17/04 Primary

  Forming tubes or rods by drawing from stationary or rotating tools or from forming nozzles · CPC title

• Y02P40/57

  Improving the yield, e-g- reduction of reject rates · CPC title

• C03C23/0075

  Cleaning of glass (specially adapted to plate glass B08B11/00) · CPC title