# US 2016/0257596 A1 · Method and apparatus for minimizing inclusions in a glass making process > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0257596 A1 - Document ID: US20160257596A1 - Status: Published application - Kind: A1 - Application number: 15/155,196 - Filed: 2016-05-16 - Published: 2016-09-08 - Earliest claimed: 2007-05-18 - Assignees: Corning Incorporated - Applicants: Corning Incorporated - Inventors: Andrey V. Filippov; Chunhong Chelsie He; Bulent Kocatulum; Kathleen Elizabeth Morse; Liming Wang - Web page: https://patentgrep.com/patent/US20160257596A1 ## CPC - C03B 17/064: {by the overflow downdraw fusion process; Isopipes therefor} - C03B: MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES ## Abstract A method for forming a glass sheet with reduced inclusions is disclosed. The method includes flowing molten glass over converging forming surfaces of a forming body positioned within an enclosure. The forming body is heated with a plurality of heating elements separated from the forming body by an inner wall of the enclosure. The temperature T2 at the bottom of the forming body is decoupled from the temperature T1 at the top of the forming body by an insulating thermal barrier positioned between two adjacent heating elements of the plurality of heating elements such that a change in T2 does not cause a substantial change in T1. ## Claims ### Claim 1 A method for forming a glass sheet comprising: flowing molten glass over a forming body comprising converging forming surfaces that converge at a bottom of the forming body, the forming body positioned within an enclosure; heating the forming body with a plurality of heating elements separated from the forming body by an inner wall of the enclosure to form a temperature gradient between a temperature T1 at a top of the forming body and a temperature T2 at the bottom of the forming body, an insulating thermal barrier positioned between two adjacent heating elements of the plurality of heating elements; drawing the molten glass from the bottom of the forming body to form a glass sheet; and wherein the temperature T2 at the bottom of the forming body is decoupled by the insulating thermal barrier from the temperature T1 at the top of the forming body such that a change in T2 does not cause a substantial change in T1. ### Claim 2 (depends on 1) The method according to claim 1, wherein a 1° C./hour change in T2 results in less than a 0.5° C./hour change in T1. ### Claim 3 (depends on 1) The method according to claim 1, wherein a thermal resistance of the insulating thermal barrier is greater than about 0.0004 K·m2/W. ### Claim 4 (depends on 3) The method according to claim 3, wherein the thermal resistance of the insulating thermal barrier is greater than about 0.004 K·m2/W. ### Claim 5 (depends on 1) The method according to claim 1, wherein the glass sheet comprises less than about 0.3 inclusions per pound of finished glass. ### Claim 6 (depends on 1) The method according to claim 1, wherein the glass sheet comprises less than about 0.09 inclusions per pound of finished glass. ### Claim 7 (depends on 1) The method according to claim 1, wherein the insulating thermal barrier is positioned between a bottom-most heating element of the plurality of heating elements and a vertically adjacent heating element. ### Claim 8 (depends on 1) The method according to claim 1, wherein the heating comprises radiating more heat from ends of the plurality of heating elements than from centers of the heating elements. ### Claim 9 (depends on 1) The method according to claim 1, wherein the inner wall comprises an upper inner wall portion and a lower inner wall portion, the method further comprising heating the forming body by passing an electric current through the lower inner wall portion. ### Claim 10 A method for forming a glass sheet comprising: flowing molten glass over a forming body comprising converging forming surfaces that converge at a bottom of the forming body, the forming body positioned within an enclosure; forming a temperature gradient between a temperature T1 at a top of the forming body and a temperature T2 at the bottom of the forming body by heating the forming body with a plurality of heating elements separated from the forming body by an inner wall of the enclosure, an insulating thermal barrier positioned between a bottom-most heating element of the plurality of heating elements and a vertically adjacent heating element of the plurality of heating elements; drawing the molten glass from the bottom of the forming body to form a glass sheet; and wherein the temperature T2 at the bottom of the forming body is decoupled by the insulating thermal barrier from the temperature T1 at the top of the forming body such that a 1° C./hour change in T2 results in less than a 0.5° C./hour change in T1. ### Claim 11 (depends on 10) The method according to claim 10, wherein the heating comprises radiating more heat from ends of the plurality of heating elements than from centers of the heating elements. ### Claim 12 (depends on 10) The method according to claim 10, wherein the glass sheet comprises less than about 0.3 inclusions per pound of finished glass. ### Claim 13 (depends on 12) The method according to claim 12, wherein the glass sheet comprises less than about 0.09 inclusions per pound of finished glass. ### Claim 14 (depends on 10) The method according to claim 10, wherein the inner wall comprises an upper inner wall portion and a lower inner wall portion, the method further comprising heating the forming body by passing an electric current through the lower inner wall portion. ### Claim 15 (depends on 14) The method according to claim 14, wherein the upper inner wall portion is separated from the lower inner wall portion by the insulating thermal barrier. ### Claim 16 A method for forming a glass sheet comprising: flowing molten glass over a forming body comprising converging forming surfaces that converge at a bottom of the forming body, the forming body positioned within an enclosure; heating the forming body with a plurality of heating elements separated from the forming body by an inner wall of the enclosure to obtain a temperature T1 at a top of the forming body and a temperature T2 at the bottom of the forming body, an insulating thermal barrier horizontally positioned between two adjacent vertically spaced heating elements of the plurality of heating elements; drawing the molten glass from the bottom of the forming body to form a glass sheet; and wherein the temperature T2 at the bottom of the forming body is decoupled by the insulating thermal barrier from the temperature T1 at the top of the forming body such that a change in T2 does not cause a substantial change in T1. ### Claim 17 (depends on 1) The method according to claim 1, wherein a 1° C./hour change in T2 results in less than a 0.5° C./hour change in T1. ### Claim 18 (depends on 16) The method according to claim 16, wherein the insulating thermal barrier is positioned between a bottom-most heating element of the plurality of heating elements and a vertically adjacent heating element of the plurality of heating elements. ### Claim 19 (depends on 16) The method according to claim 16, wherein the glass sheet comprises less than about 0.09 inclusions per pound of finished glass. ### Claim 20 (depends on 16) The method according to claim 16, wherein the heating comprises radiating more heat from ends of the plurality of heating elements than from centers of the heating elements.