Circumferential Welding Structure for Fatigue-Resistant Valve Joints
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Solution Overview
Problem
The existing welding structure of valve devices experiences stress and fatigue at the welded parts when shifting from a valve-open to a valve-closed state, leading to potential fatigue destruction, and increasing welding depth to address this issue results in higher welding output, causing distortion and reduced corrosion resistance.
Innovation Solution
A welding structure with a plurality of welding spots arranged to form a curved outer periphery, where the outer side-face portion of the welding spots intersects the second member, setting a weld angle of 65° or more to enhance endurability without increasing welding depth, and providing a clearance between the first and second members to concentrate stress on specific spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If welding depth is increased to improve endurability of the welded part, then the endurability is improved, but welding output increases and causes more heat application leading to welding distortion and sensitization
Solution Approach 1:
The patent divides the welding structure into multiple discrete welding spots arranged in a circumferential pattern around the insertion hole, rather than using a single deep weld. This segmentation allows the load and stress to be distributed across multiple locations, improving endurability without requiring each individual weld to be deeply penetrating or high-output
Solution Approach 2:
The patent transitions from a single-point welding approach to a multi-point circumferential arrangement, effectively moving from a one-dimensional deep weld concept to a two-dimensional distributed pattern. The welding spots are arranged around the circumference of the insertion hole, creating a radial distribution that enhances structural integrity without increasing weld depth or power requirements
2Length of stationary object
If welding output is increased to achieve deeper welding, then welding depth increases, but heat application increases causing welding distortion and sensitization
Solution Approach 1:
The patent employs multiple welding spots that collectively provide sufficient bonding strength without requiring each spot to achieve maximum penetration depth. The cumulative effect of multiple partial welds around the circumference achieves the desired structural integrity while avoiding the excessive heat input that would cause distortion and sensitization in a single deep weld
3Reliability
If multiple welding spots are provided to expand weld angle and improve endurability, then endurability improves without increasing welding depth, but the complexity of welding structure increases
Solution Approach 1:
The circumferential arrangement of welding spots serves multiple functions simultaneously: it distributes stress, expands the effective weld angle, prevents rotational movement, and provides redundant bonding paths. This geometric configuration achieves enhanced endurability and structural stability through a single design feature rather than requiring multiple separate components or complex assembly procedures
Data Source
AI summary
A welding structure includes, in a cross-section of the first member and the second member when they are seen from an axial direction of the insertion hole, a plurality of welding spots, an outer periphery of the welding spots are each formed with a curve-shaped portion and two side-face portions. When two intersections where the outer side-face portion on the outer periphery of the both-end welding spots and the outer periphery of the second member intersect are defined as a first intersection and a second intersection, a weld angle formed by a first linear line linking the first intersection with a sectional center of the second member and a second linear line linking the second intersection with the sectional center of the second member is set to a first predetermined angle or more.