Process and apparatus for producing glass plate

Abstract

A process for producing a glass plate (C) which comprises: a forming step in which a molten glass (A) is fed to a trough (10) disposed in a forming furnace (11) and the molten glass (A) is caused to flow down from the trough (10) through a conveyance passage (18) extending vertically to thereby stretch and form the glass (A) into a platy glass ribbon (B); an annealing step in which internal strain in the glass ribbon (B) is removed in an annealing lehr (12); a cooling step in which the glass ribbon (B) is cooled to around room temperature; and a cutting step in which the glass ribbon is cut into a given size, the pressure of the atmosphere surrounding the forming furnace (11) and / or annealing lehr (12) being elevated.

Description

technical field [0001] The present invention relates to a method for manufacturing a glass sheet formed by flowing molten glass from a forming body to extend in a vertical direction to form a glass ribbon, and to a manufacturing facility thereof. Background technique [0002] As a method for producing plate glass for various electronic devices, especially flat panel displays such as liquid crystal displays, there is known a down-draw method in which molten glass is flowed down from a molded body and stretched into a glass ribbon in a vertical direction to form a glass plate. [0003] The down-draw method includes two methods, the overflow down-draw method and the slit down-draw method, and the overflow down-down method in particular is widely known as a method capable of obtaining a glass plate with very small surface waviness and roughness and excellent surface quality. [0004] The so-called overflow down-draw method is to form a plate-shaped glass ribbon by making molten ...

AI Technical Summary

Problems solved by technology

That is, in the transport path of the glass ribbon, the low-temperature air flow always rises along the surface of the glass ribbon, and thus the temperature of the atmosphere in the annealing furnace tends to fluctuate.

Japanese Patent Application Laid-Open No. 5-139766 discloses that a convection prevention plate is formed in an annealing furnace, but the convection prevention plate cannot sufficiently block the flow of low-temperature air near the surface of the glass ribbon.

Furthermore, if the convection prevention plate is to be used to completely prevent low-temperature air flow, the distance between the glass ribbon and the convection prevention plate needs to be formed very small, and there is a possibility that the glass ribbon will contact the convection prevention plate and cause damage to the surface.

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