Sealed Welded Joint Structure for Dissimilar Metal Corrosion Control
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Solution Overview
Problem
Existing joint structures between dissimilar metal materials are prone to electrolytic corrosion due to moisture ingress, which weakens the joint strength.
Innovation Solution
A joint structure featuring a recess around the welding area with injection holes for sealing material to fill and seal the gap between overlapping surfaces, preventing moisture entry and enhancing sealing properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a through-portion is used to join dissimilar metal materials, then welding is enabled between the first member and third member, but moisture enters through the gap between overlapped surfaces causing electrolytic corrosion
Solution Approach 1:
The joint structure is divided into functional zones: the through-portion for welding, the recess for sealing, and the gap for moisture exclusion. This segmentation allows each zone to perform its specific function - welding provides joining capability while the recess-sealing system provides corrosion protection
Solution Approach 2:
The recess acts as an intermediary structure between the welding zone and the environment. It provides a dedicated space for sealing material that mediates between the need for welding access (through-portion) and the need for moisture protection (sealing), preventing direct contact between moisture and the metal interface
2Ease of manufacture
If overlapped surfaces are kept flat for simple manufacturing, then manufacturing is easier, but gaps allow moisture entry and electrolytic corrosion
Solution Approach 1:
The recess is formed in advance during manufacturing, before assembly and sealing. This preliminary action creates the sealing cavity structure that will later receive the sealing material, preventing corrosion before it can occur
Solution Approach 2:
The solution moves from a two-dimensional flat surface problem to a three-dimensional solution by creating a recess (depth dimension). This additional dimension provides space for sealing material while maintaining simple flat overlapped surfaces for ease of manufacturing
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 solution effectively reduces electrolytic corrosion and secures the joining strength by ensuring a tight seal between dissimilar metal materials, improving the durability of the joint.
Implementation Method 1
the sealing material closes a gap between overlapped surfaces of the first member and the second member
Implementation Method 2
the recess is provided with a sealing material injected from the injection hole, the sealing material closing a gap between the overlapped surfaces
Implementation Method 3
the dissimilar material and the first metal material are fixed to each other by a compressive fixing force between the flange and the first metal material due to solidification shrinkage of the filler material
Implementation Method 4
a filler material (welding wire) is arc-welded through a through-portion of the dissimilar material
Data Source
Figure 1
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AI summary
A second member 20 has a through-portion 21 penetrating toward a first member 10. An overlapped surface of the second member 20 with the first member 10 includes a recess 41. The recess 41 is recessed so as to surround an entire periphery of the through-portion 21. A sealing material 40 is injected into the recess 41 from an injection hole 42 to close a gap between overlapped surfaces of the first member 10 and the second member 20.