Laminated Glass Float Process Strength Integration
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Solution Overview
Problem
Existing methods for strengthening glass articles, such as chemical and thermal tempering, increase production costs and productivity losses due to additional processing steps and handling, which can damage larger glass articles, and are not suitable for forming large-width laminated glass sheets with low liquidus viscosity glass compositions.
Innovation Solution
A method and apparatus for forming laminated glass sheets by creating a multi-layer glass melt from a molten core glass and cladding glass with a specific thickness ratio, which is then directed onto a float tank, allowing the width to increase and thickness to decrease while maintaining the thickness ratio as it solidifies, using a slot draw apparatus oriented at a specific angle over a float tank containing a molten metal bath.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical or thermal tempering processes are used to strengthen glass articles, then the glass strength is improved, but the production cost increases and productivity decreases due to additional processing steps and handling
Solution Approach 1:
The patent applies preliminary action by incorporating the strengthening function directly into the glass formation process itself. The multi-layer glass melt is formed with a core glass having different thermal expansion properties than the cladding glass, creating internal stresses that strengthen the glass during the float process, before the glass leaves the float tank. This eliminates the need for subsequent tempering operations.
Solution Approach 2:
The patent merges the glass formation process with the glass strengthening process into a single integrated operation. The float glass process, which normally only forms the glass sheet, is modified to simultaneously create the laminated multi-layer structure with inherent strengthening properties, combining two previously separate functions into one process.
2Strength
If chemical or thermal tempering processes are used to strengthen glass articles, then the glass strength is improved, but the production cost increases due to additional processing steps and handling
Solution Approach 1:
The strengthening effect is built into the glass structure during formation, eliminating the need for costly post-processing tempering operations. The multi-layer configuration with different thermal expansion coefficients is created during the float process itself, providing inherent strengthening without additional manufacturing steps.
Solution Approach 2:
The patent combines glass formation and glass strengthening into a single process, eliminating the need for separate tempering equipment and operations. This integration reduces capital investment, operational costs, and complexity associated with multiple processing stages.
3Adaptability or versatility
If traditional fusion lamination processes are used, then glass articles can be formed, but glass compositions with low liquidus viscosities cannot be processed
Solution Approach 1:
The patent modifies the process parameters by using a slot draw apparatus that delivers molten glass horizontally onto the float tank surface, rather than using traditional vertical fusion lamination. This parameter change allows glass compositions with low liquidus viscosities to be processed successfully, as the horizontal delivery method prevents the glass from running or spreading uncontrollably.
Solution Approach 2:
The patent replaces the mechanical compression and heating system of traditional fusion lamination with a gravity-based float process. The slot draw apparatus delivers the glass melt onto the float tank surface where it spreads and forms under controlled conditions, eliminating the need for complex mechanical pressing systems that cannot handle low viscosity glasses.
4Strength
If larger glass articles are handled during additional processing steps, then strengthening can be achieved, but damage to the glass articles increases
Solution Approach 1:
The glass is strengthened during the formation process itself, while the glass is still in a plastic state on the float tank and before it is cut or handled as a finished article. This preliminary strengthening occurs when the glass is most vulnerable, preventing subsequent damage during handling and processing.
Solution Approach 2:
By combining glass formation and strengthening into one process, the patent eliminates multiple handling operations that would expose large glass articles to damage risks. The glass remains on the float tank continuously from formation through strengthening, minimizing the number of times it must be moved, positioned, or supported.
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 enables the production of strengthened laminated glass sheets with varying widths and thicknesses, including large-width sheets, without the need for secondary processing, reducing production costs and losses, and is compatible with glass compositions having low liquidus viscosities not suitable for traditional fusion lamination processes.
Implementation Method 1
The multi-layer glass melt may flow over the surface of the molten metal bath such that the width Wm of the multi-layer glass melt increases, the melt thickness Tm decreases
Implementation Method 2
The multi-layer glass melt may flow over the surface of the molten metal bath such that the width Wm of the multi-layer glass melt increases, the melt thickness Tm decreases
Implementation Method 3
the core to cladding thickness ratio Tc:Tcl remains constant as the multi-layer glass melt solidifies into a laminated glass sheet
Data Source
AI summary
According to one embodiment, a method for forming a laminated glass sheet includes forming a multi-layer glass melt from a molten core glass and at least one molten cladding glass. The multi-layer glass melt has a width Wm, a melt thickness Tm and a core to cladding thickness ratio Tc:Tcl. The multi-layer glass melt is directed onto the surface of a molten metal bath contained in a float tank. The width Wm of the multi-layer glass melt is less than the width Wf of the float tank prior to the multi-layer glass melt entering the float tank. The multi-layer glass melt flows over the surface of the molten metal bath such that the width Wm of the multi-layer glass melt increases, the melt thickness Tm decreases, and the core to cladding thickness ratio Tc:Tcl remains constant as the multi-layer glass melt solidifies into a laminated glass sheet.