Microwave Glass Laminate Fabrication Selective Heating
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Solution Overview
Problem
Traditional thermal approaches in glass laminate fabrication are non-selective, failing to efficiently manage the thermal and viscosity profiles of various glass layers, which limits their application in forming, cutting, finishing, and reshaping processes, particularly for laminates with different microwave absorption characteristics.
Innovation Solution
The use of in-situ selective microwave heating, in combination with conventional heating methods, to control the thermal and viscosity profiles of glass laminates by exploiting the dielectric loss differences between microwave absorbing and transparent layers, allowing for precise temperature management and viscosity control across the laminate thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional thermal heating is used from outer layer to inner core, then the outer glass layer temperature and viscosity can be changed efficiently, but the thermal and viscosity profiles of inner core layers cannot be controlled selectively
Solution Approach 1:
The patent applies local quality by making different layers of the glass laminate have different microwave absorption characteristics. The core layer is formulated with specific glass compositions (containing metal oxides like Fe2O3, CuO, NiO) that give it high microwave loss tangent, while outer layers use compositions with lower loss tangent. This allows selective heating of the core layer when microwave radiation is applied, enabling independent thermal profile control of each layer without affecting others uniformly.
Solution Approach 2:
The patent replaces conventional thermal conduction heating (which heats from outer surfaces inward through thermal diffusion) with microwave electromagnetic radiation heating. This substitution enables volumetric heating throughout the laminate thickness simultaneously, with the ability to selectively heat specific layers based on their dielectric properties, rather than relying on heat conduction from external sources.
2Device complexity
If non-selective heating is used, then heating process is simpler, but thickness variations and center tension cannot be minimized
Solution Approach 1:
By formulating the core layer with glass compositions having high microwave loss tangent (containing metal oxides such as Fe2O3, CuO, NiO in specific ranges), the core layer absorbs microwave energy preferentially. This localized energy absorption enables precise control of core layer temperature and viscosity during processing, allowing thickness variations to be minimized and center tension to be reduced through controlled thermal profiles specific to each layer.
3Device complexity
If conventional heating is used, then equipment is simpler, but edge finishing and 3D shaping cannot be optimized
Solution Approach 1:
The patent replaces conventional external thermal conduction heating with microwave electromagnetic radiation heating. This enables volumetric heating throughout the laminate, providing superior thermal penetration and uniformity. The selective absorption by different layers based on their dielectric properties allows precise control of temperature and viscosity profiles, optimizing edge finishing quality and enabling complex 3D shaping operations that require controlled thermal states throughout the entire laminate thickness.
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 efficient thermal profile management, minimizes thickness variations, optimizes edge finishing, and facilitates the formation of complex 3D shapes, reducing center tension and mitigating fracture risks during cutting processes, while maintaining a desired temperature profile across the laminate sheet.
Implementation Method 1
The microwave radiation heating techniques disclosed herein can be used to preferentially heat the glass layer with the higher dielectric loss
Implementation Method 2
The dielectric loss of a glass determines how susceptible the glass is to microwave heating
Implementation Method 3
microwave heating can be used in combination with conventional heating approaches such as infrared (IR), convection and conduction
Implementation Method 4
microwave heating can be used in combination with conventional heating approaches such as infrared (IR), convection and conduction
Implementation Method 5
microwave heating can be used in combination with conventional heating approaches such as infrared (IR), convection and conduction
Data Source
AI summary
Methods of fabricating a glass laminate is provided. According to one embodiment, a glass laminate comprised of a microwave absorbing layer and a microwave transparent layer is formed. The microwave absorbing layer is characterized by a microwave loss tangent δH that is at least a half order of magnitude larger than a loss tangent δL of the microwave transparent layer. An area of the glass laminate is exposed to microwave radiation. The exposed area comprises a cross-laminate hot zone having a cross-laminate hot zone temperature profile. Substantially all microwave absorbing layer portions of the hot zone temperature profile and substantially all microwave transparent layer portions of the hot zone temperature profile reside above the glass transition temperature TG of the various layers of the glass laminate prior to impingement by the microwave radiation. In accordance with another embodiment, a method of fabricating a glass laminate is provided where the exposed area of the glass laminate is characterized by a viscosity below approximately 1×104 poise.