Metal Member Welding with Fine Grain Layers and Flat Joints
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Solution Overview
Problem
Existing friction stir spot welding methods result in deep indentations that detract from the aesthetics of the product, facilitate moisture collection, and degrade the reliability of the weld due to complex tool configurations and high welding loads, especially when using tools without a stirring pin.
Innovation Solution
A welding method that forms a fine crystal grain layer on the surface of metal members using a friction stir processing tool without a stirring pin, followed by pressing and heating to achieve welds with a flat-surfaced tool, thereby suppressing deep indentations and enhancing weld reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a welding tool with a stirring pin is used for friction stir spot welding, then weld strength is improved, but deep indentation is formed in the welded portion
Solution Approach 1:
The invention extracts and removes the stirring pin component from the welding tool, retaining only the shoulder portion. This eliminates the source of deep indentation while preserving the welding function through alternative mechanisms such as friction heat generation and material softening at the interface
Solution Approach 2:
The invention introduces a fine crystal grain layer as an intermediary between the metal plates. This layer facilitates welding without requiring a stirring pin, as it enables material flow and bonding through its unique microstructure while preventing deep indentation formation
2Shape
If the stirring pin and shoulder are separate bodies driven individually, then deep indentation is suppressed, but device complexity and cost increase
Solution Approach 1:
The invention merges the stirring pin and shoulder into a single integrated body. By combining these components, the tool structure is simplified while maintaining the ability to suppress deep indentation through the optimized shoulder design and fine crystal grain layer mechanism
3Strength
If the shoulder is deeply inserted into the top plate to achieve weld strength without a stirring pin, then weld strength is improved, but deep indentation is formed
Solution Approach 1:
The invention changes the physical state and microstructure parameters of the material at the welding interface by forming a fine crystal grain layer. This parameter change enables adequate weld strength to be achieved with reduced shoulder insertion depth, thereby preventing deep indentation formation
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 method prevents deep indentations, reduces moisture collection, and maintains weld strength by using a simple tool configuration, thus improving the aesthetics and reliability of the welded product.
Implementation Method 1
a process of forming a first layer in a first member on a first backing plate by rotating a friction stir processing (FSP) tool to perform FSP, the first layer including a fine crystal grain structure
Implementation Method 2
a process of pressing and heating an area of a surface of the second member at a side opposite to the first member side, the area overlapping the first layer
Data Source
AI summary
A welding method of metal members includes a process of forming a fine crystal grain layer at a surface being weld of one metal member or both of metal members by friction stir processing using rotating a friction stir processing tool; a process of overlapping the metal members to face the surface being welded each other; and a process of pressing and heating from area the surface opposite to the surfaces being welded of metal members.