Method for hermetically sealing a double-walled glass tube
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Solution Overview
Problem
Existing methods for vacuum-tight sealing of double-walled glass tubes in thermal solar collectors face challenges such as contamination from combustion residues, complexity, and expense in handling vacuum conditions, particularly with gas flames and laser processes, leading to tightness issues.
Innovation Solution
The method employs electro-conductive heating using ceramic or metallic heating conductors that directly contact the glass tubes within a vacuum chamber, allowing for efficient heat transfer and deformation without external materials, minimizing contamination and vacuum feedthroughs, enabling rapid and airtight sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gas flame methods are used for sealing, then the sealing process can be performed, but contamination from combustion residues occurs leading to tightness problems
Solution Approach 1:
The patent replaces the chemical combustion process with an electro-conductive heating process. Heating conductors made of electro-conductive material are applied to the glass tube surface, and electric current is passed through them to generate heat directly at the sealing location. This eliminates combustion residues and contamination while achieving the necessary heating for glass softening and sealing.
2Temperature
If laser processes are used for heating, then direct heating can be achieved, but focusing in the vacuum recipient becomes very complicated and expensive
Solution Approach 1:
The patent introduces heating conductors as an intermediary element between the power source and the glass tube. These conductors are applied directly to the glass tube surface and serve as the medium for heat transfer. This eliminates the need for complex laser focusing systems inside the vacuum chamber while achieving efficient direct heating through the conductive path from the heating conductors to the glass material.
3Reliability
If glass solders are used for sealing, then external heating is required, but additional materials and complexity are introduced
Solution Approach 1:
The patent removes the glass solder material from the sealing process entirely. Instead of using external glass solder that needs to be heated and applied, the invention uses the glass tube material itself as the sealing medium by heating it directly through electro-conductive heating conductors. This eliminates the need for additional solder materials and simplifies the overall sealing process.
4Reliability
If traditional heating methods are used, then sealing can be achieved, but the process is slow and less efficient
Solution Approach 1:
The patent changes the heating method from indirect thermal conduction or radiation to direct electro-conductive heating. By applying electric current directly through the heating conductors that are in contact with the glass tube, the heating efficiency is dramatically increased. This allows rapid heating to the glass softening temperature, significantly reducing the sealing cycle time while maintaining high sealing quality.
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 simplifies the sealing process, reduces contamination risks, and enhances the efficiency of vacuum-tight sealing, allowing for faster production with minimal equipment and lower operational costs while maintaining high thermal insulation standards.
Implementation Method 1
The heating conductors can be applied to an inner and/or an outer surface of the glass tube. This enables direct heat transfer to the surface of the glass tubes.
Implementation Method 2
The electro-conductive heating according to the present invention... The at least two heating conductors are also located in the vacuum chamber and are installed there... the glass tubes to be heated and sealed by directly applying the heating conductors to a surface of the double-walled glass tube.
Data Source
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AI summary
Method and device (300) for the vacuum-tight sealing of a double-walled glass tube, in particular a manufacturing method for the production of solar collectors. Electro-conductive heating and subsequent deformation of the double-walled glass tube can be achieved by means of a vacuum chamber provided, in which a holding element (301, 302) is fixed and in which a heating conductor (301, 302) is arranged. No additional materials such as metallic auxiliary elements or solders are required. A simple installation in the vacuum chamber is possible and a minimum required vacuum bushing for the power supply of a heating conductor is required. The direct transfer of heat to the double-walled glass tube and the resulting rapid process control make it possible to safely seal a double-walled glass tube of a thermal solar collector under vacuum using simple means.