Hermetic Glass-to-Metal Seal Using Intermediate Compression
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Solution Overview
Problem
Conventional hermetic glass-to-metal seal assemblies face limitations in material selection due to difficulties in joining glass, metallic rings, and conductors, leading to high manufacturing costs and complexity, especially in high-pressure applications where skilled labor is required for laser welding to avoid heat shocks.
Innovation Solution
A hermetic glass-to-metal seal assembly is achieved by using an intermediate component with a higher coefficient of thermal expansion than the glass component, which is compressed by an outer ring to form a compression seal, allowing for a wider selection of materials and simplifying the manufacturing process through a method involving heating, fusion, and cold-shrinking to create a durable and pressure-resistant seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional materials and joining methods are used for glass-to-metal seals, then hermetic sealing is achieved, but material selection is limited and manufacturing cost is high
Solution Approach 1:
The patent introduces an intermediate component between the glass and metal parts that acts as a mediator. This intermediate component has a coefficient of thermal expansion between that of the glass and metal, enabling thermal expansion compatibility. It also provides a surface that can be joined to both glass and metal, thereby expanding material selection while simplifying the joining process and reducing manufacturing cost.
Solution Approach 2:
The patent changes the thermal expansion parameter by introducing an intermediate component with a specific coefficient of thermal expansion that lies between those of the glass and metal components. This parameter matching enables compatible thermal behavior during heating and cooling cycles, allowing wider material selection without compromising seal integrity or increasing manufacturing complexity.
2Ease of manufacture
If laser welding is used to join metal ring to process tube, then joining is achieved, but skilled labor is required and manufacturing time increases
Solution Approach 1:
The intermediate component serves as a mediator that can be joined to the metal ring using simpler, less skill-intensive methods such as brazing or soldering, rather than requiring laser welding. This reduces the need for skilled labor and decreases manufacturing time while maintaining joint integrity.
Solution Approach 2:
The patent replaces the laser welding process (which requires precise control and skilled operation) with alternative joining methods such as brazing or soldering through the intermediate component. This substitution reduces manufacturing complexity and time while achieving equivalent or superior joining results.
3Reliability
If metal ring is made of high melting point material to avoid oxidation, then oxidation resistance is improved, but joining difficulty increases
Solution Approach 1:
The intermediate component acts as a buffer between the high melting point metal ring and the glass, enabling joining without requiring the metal ring itself to be directly joined to the glass. This intermediary layer facilitates easier joining processes while the metal ring maintains its oxidation-resistant properties.
Solution Approach 2:
The patent segments the joining interface by introducing an intermediate component, separating the metal ring from direct contact with the glass. This allows the metal ring to be made of high melting point, oxidation-resistant materials without compromising joinability, as the intermediate component handles the joining interface.
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 solution enables a cost-effective and efficient manufacturing process with a wide selection of materials, reducing manufacturing time and costs while achieving a durable, pressure-resistant hermetic seal with low leakage rates, suitable for various applications including sight glass and terminal assemblies.
Implementation Method 1
The intermediate component has a different coefficient of thermal expansion than the glass component
Implementation Method 2
cold-shrinking to form a compression seal
Implementation Method 3
heating, fusion, and cold-shrinking
Data Source
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AI summary
A glass-to-metal hermetic seal assembly in a sight glass assembly or a hermetic terminal assembly is disclosed and includes a glass component, an intermediate component, and an outer ring. The intermediate component is provided around the glass component. The glass component is fused to the intermediate component. The outer ring, which has a coefficient of thermal expansion that is greater than a coefficient of thermal expansion of the glass component, compresses the intermediate component against the glass component to create a hermetic compression seal.