Switching Device Weld Tabs for Seal Integrity
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Solution Overview
Problem
Existing switching devices face challenges in maintaining seal integrity due to operator dependency in welding processes, leading to excessive weld arc energy application and potential leaks, particularly in applications requiring stringent environmental sealing standards like military specifications.
Innovation Solution
The integration of raised integral weld tabs on the housing provides a controlled target for weld material, reducing operator skill requirements and ensuring a consistent seal by directing weld energy effectively, while using stainless steel components for enhanced corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If TIG welding is used to affix the thin body to the housing, then the body and housing can be bonded together, but excessive weld arc energy is applied to the thin wall of the bushing creating holes or excessively thin regions that compromise seal integrity
Solution Approach 1:
The patent introduces an intermediary component (the collar with integrated weld tabs) between the welding arc and the thin-walled bushing. The weld tabs serve as a mediator that receives the weld arc energy and transfers it to the bushing in a controlled manner, preventing direct application of excessive energy to the thin walls while ensuring adequate bonding strength.
Solution Approach 2:
The patent applies local quality by providing weld tabs only at specific locations where welding is needed, rather than welding the entire circumference. The tabs are strategically positioned to concentrate weld energy where required while leaving other areas of the bushing intact and preserving seal integrity.
2Ease of manufacture
If welding operation is performed on thin body to housing, then components are bonded together, but high level of operator skill is required to obtain acceptable welds that do not compromise seal integrity
Solution Approach 1:
The weld tabs are designed to be self-aligning and self-regulating. The tab's geometry and position automatically guide the welding process, allowing the welding operation to proceed with standard procedures rather than requiring highly skilled operators to manually control arc placement and energy input.
Solution Approach 2:
The weld tabs are pre-formed as integral parts of the collar assembly before the welding operation. This preliminary preparation of the welding surface and geometry eliminates the need for operators to perform complex adjustments during welding, significantly reducing skill requirements.
3Strength
If weld arc energy is directed at the flat top surface of the housing to push or splatter molten material onto the bushing wall, then a weld can be created, but holes or excessively thin regions are created in the thin bushing walls
Solution Approach 1:
The weld tab acts as an intermediary that intercepts the weld arc energy before it can directly impact the thin bushing wall. The tab absorbs and redistributes the thermal energy, preventing localized overheating and material loss that would create holes or thin regions in the bushing.
Solution Approach 2:
The patent transitions from a two-dimensional welding surface (flat top of housing) to a three-dimensional structure with protruding tabs. This dimensional change provides a new welding plane that is offset from the bushing wall, allowing energy deposition without direct contact with the thin wall.
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 achieves a sealed switching device with a leak rate of ≤10−6 cm3/s at 25°C and one atmosphere differential pressure, improving manufacturability and reducing leaks by providing a fixed amount of weld material and thermal shielding, thus enhancing seal integrity and reducing operator dependency.
Implementation Method 1
The weld tab provides weld material to physically bond the outer surface of the sensing body to the housing
Data Source
AI summary
A switching device includes a housing having an exterior surface with at least one opening in the surface. An inner edge of the opening is for receiving and securing solid bodies. At least a portion of the inner edge of the opening includes an integral weld tab which is raised above a level of the exterior surface. A sensing body includes a sensing structure operable to sense at least one condition. The sensing body has an outer surface that is disposed partially within the housing and secured to the edge of the opening by the weld tab, wherein the weld tab provides weld material physically bonding the outer surface of the sensing body to the housing.