Glass Sheet Annealing Pressure Control for Strain Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As glass sheets for liquid crystal displays increase in size, controlling internal strain to 1.0 MPa or less becomes challenging due to low-temperature airflow in the annealing furnace, which causes variations in atmospheric temperature and surface flaws when preventive measures are implemented.
Innovation Solution
Elevating the pressure in the outside atmosphere of the forming and annealing furnaces using a pressurizing unit, such as a fan, to prevent low-temperature airflow from entering and reduce internal strain in the glass sheet, while maintaining airtightness and adjusting pressures independently in separate chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If preventive plates or convection separation structures are used to block low-temperature airflow, then internal strain control is improved, but surface flaws occur due to glass ribbon contact with the preventive structures
Solution Approach 1:
The harmful low-temperature airflow is extracted and removed from the conveyance passage by introducing external air to counterbalance it, eliminating the need for preventive plates that cause surface flaws while maintaining internal strain control
Solution Approach 2:
External air is introduced as an intermediary substance to counterbalance the low-temperature airflow climbing in the conveyance passage, preventing surface flaws while controlling internal strain through pressure equalization
2Manufacturing precision
If the distance between glass ribbon and preventive plate is reduced to fully block low-temperature airflow, then internal strain control is improved, but surface flaws occur due to contact between glass ribbon and preventive plate
Solution Approach 1:
The preventive plate is completely removed from the system, and its function of blocking low-temperature airflow is replaced by introducing external air to counterbalance the harmful airflow, eliminating surface flaws while maintaining internal strain control
3Productivity
If glass sheet size is increased for large-size plate production, then productivity and market demand are improved, but internal strain increases making it difficult to control to 1.0 MPa or less
Solution Approach 1:
Air pressure is used to counterbalance low-temperature airflow in the conveyance passage, preventing temperature variations that cause internal strain in large glass sheets while enabling continued production of large-size plates
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses low-temperature airflow, minimizing atmospheric temperature variations and reducing internal strain in large glass sheets to 1.0 MPa or less, ensuring uniform image quality and preventing surface flaws.
Implementation Method 1
Elevating the pressure in the outside atmosphere of the forming and annealing furnaces using a pressurizing unit, such as a fan
Implementation Method 2
using a pressurizing unit, such as a fan
Data Source
AI summary
A process produces a glass sheet. The process includes down-drawing a molten glass into a sheet-like glass ribbon, in which the molten glass is fed to a forming trough arranged in a forming furnace and the molten glass is caused to flow down from the forming trough through a conveyance passage extending vertically. The process also includes removing an internal strain in the glass ribbon in an annealing furnace, cooling the glass ribbon to around room temperature, and cutting the glass ribbon in a given size, in which a pressure in an outside atmosphere of the forming furnace and/or the annealing furnace is elevated.