Apparatus and method for producing glass ribbons

Patent metadata

Field	Value
Publication number	US-12129197-B2
Application number	US-202016938092-A
Country	US
Kind code	B2
Filing date	Jul 24, 2020
Priority date	Jul 24, 2019
Publication date	Oct 29, 2024
Grant date	Oct 29, 2024

Abstract

An apparatus is provided for producing thin glass ribbons from molten glass. The apparatus includes a drawing tank, a direct heater, and an indirect heater. The drawing tank has a lower elongated nozzle opening through which the molten glass can exit downwards. The direct heater has one or more heating circuits operable to heat the drawing tank in a first heating zone. The direct heater has a power source for each on the heating circuits. Each heating circuit has connections to connected to a wall of the drawing tank so that current from the power source flows through at least a portion of the wall and heats the wall. Each heating circuit also includes current-carrying portions of the wall. The indirect heater has one or more heating elements to heat the drawing tank in a second heating zone.

First claim

What is claimed is:

1. An apparatus for producing thin glass ribbons from a molten glass, the apparatus comprising:
a drawing tank having an inlet, a wall, a nozzle opening through the wall, and a manifold pipe in communication with the inlet, the inlet being configured to receive the molten glass into the drawing tank, the manifold pipe having an upper portion with a cylindrical cross-section that is transverse to a drawing direction of the glass ribbons and along a longitudinal extension of the nozzle opening, the manifold pipe being in communication with a chamber that has a smaller cross section than the manifold pipe, wherein the nozzle opening is at a lower end of the chamber, the nozzle opening being configured to allow the molten glass to exit the drawing tank and produce the thin glass ribbons with a thickness up to 3000 μm;
a direct heater having a heating circuit and a power source, the heating circuit defining a first heating zone to heat the drawing tank, the power source operatively connected to the heating circuit, the heating circuit having power connections that connect the heating circuit to the wall so that a current from the power source flows through a current-carrying portion of the wall to heat the wall; and
an indirect heater having a heating element defining a second heating zone to heat the drawing tank, wherein the direct heater comprises at least three heating circuits defining three of the first heating zones, and wherein the three heating circuits are operatively connected to the power source so that the three heating circuits are separately controlled, the three heating circuit having different connections that connect the three heating circuit to different areas of the wall so that current from the power source flows through current-carrying portions of the wall to heat at least three different areas of the wall, which are distributed in the upper portion of the drawing tank, wherein one heating zone of the direct heater comprises a pair of collars that form the power connections and are fitted to the upper portion of the manifold pipe in the vicinity of the inlet for the molten glass.

2. The apparatus of claim 1 , wherein the heating circuits defines four of the first heating zones operatively connected to the power source so that the four of the first heating zones are separately controlled, the four of the first heating zones having different connections that connect to different areas of the wall so that current from the power source flows through current-carrying portions of the wall to heat four different areas of the wall.

3. The apparatus of claim 1 , wherein the heating element comprises three heating elements defining three of the second heating zones, the three heating elements being separately controllable and spatially distinct from one another.

4. The apparatus of claim 1 , wherein the heating element comprises five heating elements defining five of the second heating zones, the five heating elements being separately controllable.

5. The apparatus of claim 1 , wherein the heating element comprises a plurality of heating elements defining a plurality of the second heating zones, wherein the plurality of second heating zones are arranged on and around the drawing tank in a vertically and/or horizontally distributed manner.

6. The apparatus of claim 1 , wherein the current is less than 2500 A.

7. The apparatus of claim 1 , wherein the indirect heater contributes more than 50% of a total heating power output.

8. The apparatus of claim 1 , wherein the current-carrying portion of the wall is made from metal sheets having a thickness from 0.5 to 5 mm.

9. The apparatus of claim 1 , further comprising a plurality of temperature measurement points connected to the drawing tank.

10. The apparatus of claim 9 , further comprising a feedback control unit, wherein the plurality of temperature measurement points comprises at least two temperature feedback control measurement points in communication with the feedback control unit so that the feedback control unit regulates a heating power of the direct and/or indirect heater.

11. The apparatus of claim 1 , wherein the heating element comprises heating tiles or meandering heaters.

12. The apparatus of claim 1 , wherein the heating element comprises a resistance heating material selected from a group consisting of platinum, stainless steel, and SiC.

13. The apparatus of claim 1 , wherein the drawing tank comprises a fine grain stabilized noble metal or metal alloy.

14. The apparatus of claim 13 , wherein the fine grain stabilized noble metal or metal alloy is a metal selected from a group consisting of Pt, PtRh, PtAu, PtRhAu, PtIr, ZrO 2 particles.

15. An apparatus for producing thin glass ribbons from a molten glass, the apparatus comprising:
a drawing tank having a manifold pipe, a wall, and a nozzle opening through the wall, the manifold pipe having an upper portion with a cylindrical cross-section that is transverse to a drawing direction of the thin glass ribbons and along a longitudinal extension of the nozzle opening, the nozzle opening being configured to allow the molten glass to exit the drawing tank and produce the thin glass ribbons with a thickness up to 3000 μm;
a direct heater having a heating circuit and a power source, the heating circuit defining a first heating zone to heat the drawing tank, the power source operatively connected to the heating circuit, the heating circuit having power connections that connect the heating circuit to the manifold pipe so that a current from the power source flows through a current-carrying portion of the manifold pipe to heat the manifold pipe, the power connections comprising a pair of collars fitted to the upper portion of the manifold pipe; and
an indirect heater having a heating element arranged around the drawing tank and defining a second heating zone to heat the drawing tank, wherein the apparatus is configured so that more than 50% of a total heating power output is provided by the indirect heater and is configured so that the indirect heater is positioned to heat at least the drawing tank at the nozzle opening.

16. An apparatus for producing thin glass ribbons from a molten glass, the apparatus comprising:
a drawing tank having a manifold pipe, a wall, and a nozzle opening through the wall, the manifold pipe having an upper portion with a cylindrical cross-section that is transverse to a drawing direction of the thin glass ribbons and along a longitudinal extension of the nozzle opening, the nozzle opening being configured to allow the molten glass to exit the drawing tank and produce the thin glass ribbons with a thickness up to 3000 μm;
a direct heater having a heating circuit and a power source, the heating circuit defining a first heating zone to heat the drawing tank, the power source operatively connected to the heating circuit, the heating circuit having power connections that connect the heating circuit to the manifold pipe so that a current from the power source flows through a current-carrying portion of the manifold pipe to heat the manifold pipe, the power connections comprising a pair of collars fitted to the upper portion of the manifold pipe;
an indirect heater having a heating element defining a second heating zone to heat the drawing tank; and
a plurality of temperature measurement points connected to the drawing tank, wherein at least two of the plurality of temperature measurement points are positively connected to the drawing tank.

17. The apparatus of claim 16 , further comprising a feedback control unit, wherein the plurality

Assignees

• Schott Ag

Inventors

• Glacki Alexander
• Breitbach Christian
• Hunnius Holger
• Lange Ulrich
• Münch Wolfgang
• Rösel Gregor
• Wegener Holger

Classifications

• C03B17/068

  Means for providing the drawing force, e.g. traction or draw rollers · CPC title

• C03B17/067 Primary

  combined with thermal conditioning of the sheets · CPC title

• C03B7/094

  Means for heating, cooling or insulation · CPC title

• Y02P40/57

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

• C03B7/098

  electric · CPC title