Dissimilar-Material Joining Structure for Moisture-Sealed Welds
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Solution Overview
Problem
In joining structures where a material of a different type is interposed between metal materials of the same type, there is a risk of moisture ingress leading to electrolytic corrosion, which reduces the joining strength.
Innovation Solution
A joining structure is designed with protrusions on the metal members and a through portion in the interposed material, allowing the metal members to be welded via the protrusions while also welding the outer peripheral portions to seal gaps and prevent moisture invasion, potentially using laser welding and filler materials for enhanced sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a material of a different type is interposed between metal materials of the same type, then the joining structure can accommodate different material types, but moisture can enter through gaps causing electrolytic corrosion
Solution Approach 1:
The joining structure is divided into multiple welding regions: a first welding region for welding the first member and second member with the third member interposed, and a second welding region for welding the outer peripheral portions. This segmentation allows different welding approaches for different functional requirements.
Solution Approach 2:
A protrusion is provided in at least one of the first member or second member, and a through portion is formed in the third member. The protrusion acts as an intermediary element that enables welding through the third member while maintaining its interposed position, facilitating the joining of metal members with the non-metallic material between them.
2Reliability
If outer peripheral portions are welded to seal gaps, then moisture ingress is prevented, but the device complexity increases
Solution Approach 1:
The welding process is segmented into two distinct regions: a first welding region for the central joining area and a second welding region for the outer peripheral sealing area. This allows each region to be optimized for its specific function while maintaining overall structural integrity.
Solution Approach 2:
Instead of welding the entire perimeter, only the outer peripheral portions are welded in the second welding region. This partial action provides sufficient sealing to prevent moisture ingress while minimizing the complexity and resource requirements of the welding process.
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 configuration effectively seals gaps between the members, preventing electrolytic corrosion and ensuring the joining strength by filling the overlapping direction gaps and restricting moisture ingress.
Implementation Method 1
the regions of the first member and the second member corresponding to the protrusion are laser-welded to each other
Implementation Method 2
each of an outer peripheral portion of an overlapping portion of the first member and the third member and an outer peripheral portion of an overlapping portion of the second member and the third member is welded
Data Source
AI summary
A first member and a second member are formed of metal materials of the same type and a third member is formed of a material of a different type that is difficult to weld to the first member and the second member. The first member and the second member are welded to each other via a through hole with the third member interposed therebetween in a region corresponding to a first protrusion. For the first member and the third member, and the second member and the third member, each of respective outer peripheral portions of an overlapping portion of the first member and the third member and an overlapping portion of and the second member and the third member is welded.