Glass Substrate Cooling for Width Contraction Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing glass-substrate manufacturing method using down-draw processing results in significant widthwise contraction of sheet glass due to surface tension, leading to rounded edges that need to be cut off, reducing the usable width and efficiency of glass substrates.
Innovation Solution
A method that involves cooling the sheet glass after separation from the forming member, maintaining the viscosity of the side sections within a specific range (109.0-1014.5 poise) while applying tension, using cooling rollers and temperature gradients to inhibit widthwise contraction and ensure uniform thickness and reduced warpage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sheet glass is allowed to cool naturally after separation from the forming member, then the cooling process is simple, but the sheet glass contracts in the width direction due to surface tension causing rounded edges and reducing usable width
Solution Approach 1:
The patent applies different cooling intensities to different regions of the sheet glass. Cooling units are positioned to provide stronger cooling at the widthwise edges compared to the center, creating a temperature distribution that controls the solidification sequence. This local quality approach allows the edges to solidify while maintaining tension, preventing contraction and rounded edges, while the center cools more gradually.
Solution Approach 2:
The patent applies tension to the sheet glass in the width direction before the glass fully solidifies, during the critical temperature range where viscosity is between 10^9.0-10^14.5 poise. This preliminary action of applying tension during the vulnerable cooling phase prevents surface tension from causing contraction. The tension is maintained throughout the cooling process to ensure the edges remain straight.
2Device complexity
If cooling units are provided spaced away from the sheet glass at the lower end of the forming member, then the device structure is simple, but the widthwise contraction of the sheet glass cannot be sufficiently inhibited
Solution Approach 1:
The cooling units are designed with selective positioning and orientation to provide localized cooling effects. The cooling units are arranged to direct cooling airflow or contact primarily at the widthwise edges of the sheet glass, creating a temperature gradient that promotes edge solidification while maintaining center flexibility. This localized cooling approach prevents uniform contraction and maintains width dimensional stability.
Solution Approach 2:
The cooling system is divided into multiple independent cooling units that can be individually positioned and controlled. These cooling units are distributed along the length of the forming member, with specific units positioned to cool different sections of the sheet glass. This segmentation allows precise control over the cooling pattern to inhibit widthwise contraction without requiring a completely complex integrated cooling system.
3Manufacturing precision
If the viscosity of side sections is maintained within 10^9.0-10^14.5 poise during cooling, then the widthwise contraction is effectively inhibited, but the temperature control complexity increases
Solution Approach 1:
The patent controls the viscosity parameter of the glass by precisely controlling the temperature parameter during cooling. By maintaining the temperature in a range that corresponds to viscosity between 10^9.0-10^14.5 poise, the glass remains in a state where it can resist widthwise contraction. The cooling rate and temperature distribution are adjusted to keep the viscosity within this critical range throughout the cooling process, ensuring dimensional stability.
Solution Approach 2:
The temperature control system incorporates feedback mechanisms to monitor and adjust the cooling process. Temperature sensors monitor the glass temperature at various points, and this information is used to adjust the cooling unit operation to maintain the desired viscosity range. This feedback control ensures that the viscosity remains within 10^9.0-10^14.5 poise despite variations in initial conditions or environmental factors, preventing widthwise contraction.
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 inhibits widthwise contraction, increases the usable width of glass substrates, and improves warpage quality, allowing for more efficient production of high-quality glass substrates.
Implementation Method 1
the sheet glass is cooled by the atmosphere inside a furnace while flowing downward
Implementation Method 2
the sheet glass is cooled by the atmosphere inside a furnace while flowing downward
Implementation Method 3
the sheet glass contracts in the width direction due to surface tension at the same time the molten glass separates from the forming member
Data Source
AI summary
A glass-substrate manufacturing method according to an aspect of the invention is a method for manufacturing glass substrates by employing a down-draw process. In down-draw processing, a molten glass is made to overflow from a forming member and formed into a sheet glass and the sheet glass is then cooled while being drawn in a downward-flow direction. In this glass-substrate manufacturing method, after the sheet glass has separated from the forming member and when the temperature of the sheet glass is within a temperature region ranging from a temperature higher than the softening point to a temperature near the annealing point, the sheet glass is cooled by maintaining the viscosity of side sections of the sheet glass within a range of 109.0-1014.5 poise while applying a tension toward the side sections.