Method for performing a frit firing cycle in the manufacturing of a vacuum solar thermal panel
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Solution Overview
Problem
Conventional frit firing cycles in vacuum solar thermal panel manufacturing reduce the pre-stress level of tempered glass plates, posing integrity threats under atmospheric pressure, especially with thin glass plates and lightweight support structures, as they cannot maintain stress levels necessary to withstand mechanical deformation without increasing weight or cost.
Innovation Solution
A method involving a frit firing cycle where the tempered glass plate's melting area is selectively heated to a higher temperature than the rest using infrared light, concurrently with the initial heating phase, to preserve pre-stress levels, allowing for a glass-metal seal formation without significant pre-stress reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional frit firing cycle is used to form the glass-metal seal, then the sealing function is achieved, but the pre-stress level of the tempered glass plate is significantly reduced, compromising structural integrity
Solution Approach 1:
The patent applies selective heating to melt frit only at the peripheral sealing area where glass-metal bonding is required, while maintaining lower temperature in the central region of the glass plate. This localized thermal treatment preserves the pre-stress level in the majority of the glass plate while achieving the necessary sealing function at the edges.
Solution Approach 2:
The heating process is segmented into different zones: a high-temperature zone at the periphery for frit melting and sealing, and a low-temperature zone in the center for pre-stress preservation. This spatial segmentation of thermal treatment resolves the contradiction between sealing requirements and structural integrity.
2Strength
If the glass plate thickness is increased to compensate for pre-stress reduction, then the structural integrity is maintained, but the weight and manufacturing cost increase
Solution Approach 1:
By concentrating the thermal treatment only where sealing is needed (peripheral region), the patent preserves the pre-stress level in the main body of the glass plate. This allows the use of thinner glass plates without compromising overall structural integrity, thereby reducing weight and manufacturing cost.
3Strength
If the density of point contacts in the support structure is increased to reduce deformation stress, then the structural integrity is maintained, but the weight and complexity of the support structure increase
Solution Approach 1:
The patent addresses structural integrity through localized thermal treatment of the glass plate itself rather than modifying the support structure. By preserving pre-stress levels through selective heating, the original support structure configuration can be maintained without increasing point contact density, thus avoiding added weight and complexity.
4Strength
If chemical tempering is used instead of thermal tempering to increase pre-stress level, then the pre-stress level is significantly increased, but the manufacturing cost and process complexity increase
Solution Approach 1:
The patent preserves the pre-stress level that was already established during the standard thermal tempering process. By applying selective heating only after tempering and only where needed for sealing, the invention avoids the need for more expensive chemical tempering processes while maintaining adequate pre-stress levels for structural integrity.
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 use of thinner glass plates without pre-stress reduction, eliminating the need for increased glass thickness or support structure density, thus maintaining panel integrity and reducing costs.
Implementation Method 1
The selective heating phase comprises an illumination phase of said tempered glass plate with light, including infrared light
Data Source
AI summary
The present application relates to a method for manufacturing a vacuum solar thermal panel which comprises at least a tempered glass plate and a metal frame attached to said plate, the method comprising a frit firing cycle to form a glass-metal seal, the frit firing cycle comprising a first heating phase of the tempered glass plate up to a maximum temperature (Tm), being the temperature which preserves a suitable pre-stress level of the tempered glass plate. Advantageously according to the invention, the method further comprises a second heating phase (via optical radiation illumination) being a selective heating phase of a melting area of the tempered glass plate performed at a second temperature (Th) which is above the maximum temperature (Tm).