Glass Ribbon Casting with Final Thickness Control
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Solution Overview
Problem
Conventional methods for making lenses and optical components from glass compositions with low liquidus viscosities are costly and inefficient, requiring extensive processing to achieve the desired dimensions and dimensional stability.
Innovation Solution
A continuous method involving flowing glass into a caster, cooling it to a specific viscosity, and then drawing it into a glass ribbon with controlled dimensions, which eliminates the need for extensive post-processing and reduces waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional casting methods are used to form glass bars with thickness greater than final product, then the glass can be formed into usable shapes, but extensive additional processing (sawing, grinding, polishing) is required resulting in high cost and low utilization of melted glass
Solution Approach 1:
The patent applies preliminary action by forming the glass ribbon at its final thickness dimensions during the initial casting process rather than forming oversized bars that require subsequent reduction. The glass is cast between release films with spacing that defines the final thickness, eliminating the need for later grinding and polishing operations.
Solution Approach 2:
The patent extracts the unnecessary material removal steps from the manufacturing process. By casting the glass at final dimensions directly, the process eliminates the extraction of material through sawing, grinding, and polishing operations that are characteristic of conventional methods.
2Ease of manufacture
If conventional casting methods produce glass bars significantly thicker than final product, then the glass can be formed, but the utilization of melted glass is low due to extensive material removal in post-processing
Solution Approach 1:
The patent applies preliminary action by forming the glass ribbon at its final thickness dimensions during the initial casting process rather than forming oversized bars that require subsequent reduction. The glass is cast between release films with spacing that defines the final thickness, eliminating the need for later grinding and polishing operations.
3Manufacturing precision
If glass is cast into bars with thickness significantly greater than final product, then the glass can be formed into usable shapes, but extensive grinding and polishing steps are required to achieve required warp and dimensional uniformity
Solution Approach 1:
The patent applies preliminary action by forming the glass ribbon at its final thickness dimensions during the initial casting process rather than forming oversized bars that require subsequent reduction. The glass is cast between release films with spacing that defines the final thickness, eliminating the need for later grinding and polishing operations.
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 produces glass ribbons with high dimensional stability and low warpage, reducing manufacturing costs and increasing the utilization of melted glass, as the glass ribbons are produced at final dimensions comparable to the intended end products with minimal post-processing requirements.
Implementation Method 1
cooling the cast glass in the caster to a viscosity of at least 10^8 Poise
Implementation Method 2
cooling the cast glass in the caster to a viscosity of at least 10^8 Poise
Implementation Method 3
heating the cast glass to an average viscosity of less than 10^7 Poise
Implementation Method 4
heating the cast glass to an average viscosity of less than 10^7 Poise
Data Source
AI summary
A method for making a glass ribbon that includes: flowing a glass into a caster having a width (Wcast) from about 100 mm to about 5 m and a thickness (t) from about 1 mm to about 500 mm to form an a cast glass; cooling the cast glass in the caster to a viscosity of at least 108 Poise; conveying the cast glass from the caster; drawing the cast glass, the drawing comprising heating the cast glass to an average viscosity of less than 107 Poise and drawing the cast glass into a glass ribbon having a width (Wribbon) that is less than Wcast; and thereafter cooling the glass ribbon to ambient temperature. Further, the cast glass during the cooling, conveying and drawing steps is about 50° C. or higher.