Pressure Sensor Welding Method for Strain Relaxation
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Solution Overview
Problem
Traditional pressure sensors face challenges with reliable sealing and output variation due to component strain, requiring complex correction processes and affecting long-term stability, especially from welding strains and material differences.
Innovation Solution
A manufacturing method involving initial butt-welding of the cylindrical portion and pressure-introducing joint, followed by a second welding in parallel to the first weld bead, with the second weld depth between 40% to 60% of the first, to relax welding strain and ensure reliable sealing and reduced output variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal stem and housing are rigidly fixed with a screw to prevent fluid leakage, then sealing reliability is improved, but component strain increases causing output deviation
Solution Approach 1:
The patent replaces the mechanical screw-fastening system with an electron beam welding system. The electron beam welds the metal stem and housing together, eliminating the need for screws and the associated mechanical strain. The welding process creates a strain-free connection that maintains both sealing reliability and measurement precision by avoiding the stress concentration and deformation caused by rigid mechanical fastening.
Solution Approach 2:
The patent utilizes the phase transition of metal from solid to liquid and back to solid during electron beam welding. The electron beam heats the metal stem and housing to melting point, creates a molten pool, and upon cooling forms a solid weld joint. This phase transition process allows for creating a strong, sealed connection without the mechanical strain inherent in screw-fastening methods.
2Reliability
If different materials are welded to achieve corrosion resistance, then material performance is improved, but welding strain occurs due to thermal expansion differences
Solution Approach 1:
The patent employs electron beam welding parameters (high energy density, controlled heat input, precise beam positioning) to minimize thermal expansion differences between dissimilar materials. By carefully controlling welding parameters such as beam current, focal point, and travel speed, the process reduces welding strain while achieving reliable corrosion-resistant joints between different metal materials.
3Measurement precision
If the bottomed cylindrical member is lengthened to prevent strain transfer, then measurement accuracy is improved, but device size increases
Solution Approach 1:
The patent replaces mechanical strain isolation (which would require lengthening the cylindrical member) with electron beam welding that inherently creates strain-free joints. The electron beam welding process melts and fuses components without generating significant residual strain, eliminating the need for additional length to isolate strain and thereby maintaining compact device dimensions while ensuring measurement accuracy.
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 method provides a pressure sensor with reliable sealing, minimized output variation, simplified signal correction, and enhanced long-term stability, reducing the complexity and cost of the pressure sensor production.
Implementation Method 1
an end surface of the cylindrical portion (211) of the diaphragm (21) and the joint surface (112A) of the pressure-introducing joint (10) are welded by an electron beam to a depth sufficient for ensuring sealing between the cylindrical portion (211) of the diaphragm (21) and the pressure-introducing joint (10)
Data Source
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AI summary
A manufacturing method of a pressure sensor (1) that includes a pressure detector (20) having a bottomed cylindrical member (21) with a bottom including a thin-wall portion (210) and a strain detecting mechanism provided on one side of the bottom for detecting a strain of the bottom and a pressure-introducing joint (10) for introducing the fluid to be measured into the bottomed cylindrical member (21) is provided. The method includes: first welding for butt-welding an end of the cylindrical portion (211) of the bottomed cylindrical member (21) and an end of the pressure-introducing joint (10); and second welding for welding the pressure-introducing joint (10) in parallel to a first weld bead (51) formed by the first welding.