Flat Glass Aperture Frame for Thickness Uniformity
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Solution Overview
Problem
Existing methods for producing flat glasses struggle to achieve uniform thickness due to temperature fluctuations during the hot forming process, leading to high total thickness variation (TTV) and potential damage to the flawless surfaces required for applications like OLED covers and optical filters.
Innovation Solution
A method involving a hot forming zone with a frame or faceplate that thermally separates the glass ribbon at its processing temperature from regions at its transformation temperature, using contact sections to maintain a consistent distance and minimize temperature fluctuations, thereby achieving a uniform thickness and preserving the fire-polished surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If large aperture openings are provided to exclude contact between the aperture and glass ribbon, then the fire-polished surface quality is preserved, but the thermal separation between gas compartments is insufficient leading to temperature fluctuations and high TTV
Solution Approach 1:
The aperture is segmented into a frame structure with multiple separate walls instead of a single large opening. This segmentation allows each wall to be positioned close to the glass ribbon without causing contact, providing effective thermal separation while preserving surface quality. The frame creates multiple smaller barriers that collectively achieve the thermal isolation needed to reduce temperature fluctuations and TTV.
Solution Approach 2:
The frame walls are positioned at specific locations around the aperture to provide thermal separation only where needed. The contact sections are localized to specific points on the glass ribbon edges, allowing thermal separation in critical areas while maintaining large overall aperture openings for surface quality preservation. This local application of thermal separation optimizes both TTV reduction and surface protection.
2Manufacturing precision
If the aperture opening is reduced to improve thermal separation, then temperature fluctuations are reduced, but the risk of contact damage to the glass ribbon surface increases
Solution Approach 1:
The aperture is divided into a frame structure with multiple walls positioned at different locations. This segmentation allows the walls to be placed close to the glass ribbon for effective thermal separation without requiring a large reduction in overall aperture size. The segmented structure provides thermal separation efficiency while maintaining sufficient opening area to prevent contact damage.
Solution Approach 2:
The frame walls act as intermediary thermal barriers between the hot forming zone and the surroundings. These intermediary structures provide the necessary thermal separation to reduce temperature fluctuations and improve thickness uniformity, while their strategic positioning ensures they do not contact the glass ribbon surface, thus maintaining surface integrity.
3Manufacturing precision
If contact sections are added to touch the glass ribbon, then thermal separation is improved and TTV is reduced, but the risk of surface damage increases
Solution Approach 1:
Contact sections are provided only at specific localized positions on the frame, such as at the edges or corners, rather than across the entire frame surface. This local contact approach provides sufficient thermal separation to reduce TTV while limiting the contact area to minimal points that are less likely to cause surface damage. The contact sections are strategically positioned to achieve thermal separation without compromising the main fire-polished surfaces.
Solution Approach 2:
Instead of providing complete contact between the frame and glass ribbon, only partial contact at specific sections is implemented. This partial action is sufficient to achieve the desired thermal separation effect for reducing TTV, while avoiding excessive contact that would damage the surface quality. The contact sections provide just enough thermal interaction to stabilize temperature without over-contacting the glass.
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
The method effectively reduces TTV to less than 0.01, achieving a relative TTV of less than 0.01−3*10−5*(1/K)*(Va−EW)+2.8*10−8*(1/K2)*(Va−EW)2, and maintains the fire-polished surface quality, suitable for thin glasses with thicknesses below 250 μm and widths over 400 mm.
Implementation Method 1
the faceplate thermally separates the glass ribbon at its processing temperature from regions at its transformation temperature
Implementation Method 2
A hot forming zone is provided in which the glass of a glass ribbon passes through a temperature range comprising the processing temperature Va of the glass
Data Source
AI summary
The present disclosure provides a device and a method with which flat glasses with particularly uniform thickness can be obtained. The methods are drawing methods in which a glass ribbon is drawn. In the method an aperture is used which allows a defined very small slit between the glass ribbon and the aperture also in the case of a change of the position of the glass ribbon.