Thin-Wall Metallic Seal for Ultra-High Vacuum
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Solution Overview
Problem
Existing metallic seal designs for ultra-high vacuum applications require high sealing forces, which can lead to brinelling of flange surfaces and increased production costs due to complex machining steps, and are not suitable for environments with reactive chemicals.
Innovation Solution
A metallic seal design featuring a thin-wall, high height/width ratio annular column with radial ribs to reduce sealing force and manufacturing steps, incorporating a method to form the seal with fewer machining steps and maintain parallel sealing dams for efficient sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metallic seal designs are used, then UHV sealing performance is achieved, but high sealing force is required causing brinelling of flange surfaces
Solution Approach 1:
The patent changes the geometric parameters of the seal cross-section, specifically using a rectangular cross-section with optimized width and height dimensions. This parameter optimization reduces the sealing force required while maintaining the UHV leak rate performance, thereby preventing flange surface brinelling.
Solution Approach 2:
The patent employs a rounded corner design at the sealing dams of the rectangular cross-section. This curvature modification stress-distributes the compression load more evenly across the sealing interface, reducing peak stresses that would cause brinelling while maintaining effective sealing.
2Manufacturing precision
If complex machining steps are used to manufacture metallic seals, then precise sealing geometry is achieved, but production cost increases
Solution Approach 1:
The patent combines multiple sealing dams into a single integrated rectangular cross-section structure. This merging of features allows the entire seal geometry to be produced in one machining operation from a round blank, eliminating multiple machining steps and reducing production cost while maintaining precise sealing geometry.
Solution Approach 2:
The patent segments the machining process into a single optimized operation that creates both the rectangular cross-section and sealing dams simultaneously. This segmentation of the manufacturing process (consolidating steps) reduces the total number of operations required while achieving the necessary geometric precision.
3Ease of operation
If elastomeric seals are used, then ease of installation is maintained, but they are attacked by reactive chemicals limiting seal life
Solution Approach 1:
The patent uses metallic materials (such as stainless steel, nickel, or aluminum alloys) that combine the necessary mechanical properties for sealing with chemical inertness. These metals resist attack from reactive chemicals like NF3 and O2, providing long service life in semiconductor processing environments while maintaining ease of installation through similar compression-based sealing mechanisms.
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 design reduces sealing force requirements, minimizes production costs, and maintains a tight seal by controlling buckling and aligning sealing dams, enhancing durability and compatibility in reactive environments.
Implementation Method 1
the seal height is reduced as the column 3 undergoes stable buckling maintaining the sealing dam surfaces 6 and 7 parallel to the sealing surfaces of flange 9 and 10
Implementation Method 2
Elastomeric seals generally are not suitable for ultra high vacuum (UHV) sealing applications because of the inherent open structure of polymeric chains through which molecular gaseous species can diffuse
Data Source
AI summary
A metallic seal design that reduces manufacturing costs by minimizing production steps and also lowers the sealing force by incorporating a thin-wall, high height/width ratio annular column. The seal has two horizontal ribs which constrain the thin-wall column from unstable buckling to thereby reduce or eliminate the tendency of the sealing dams to become inclined to sealing flange surfaces.