Friction Stir Weld Tool Rotatable Shoulder Design
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Solution Overview
Problem
Conventional friction stir welding tools face challenges in controlling local heating and providing uniform heating at joints, leading to issues such as non-uniform mixing and material flow that can foul internal hardware and cause maintenance problems, while modifications to pin geometry to address these issues result in weld defects like hook features and non-uniform mixing.
Innovation Solution
A friction stir welding tool with a rotatable body and pin integrally formed with a rotatable shoulder, and a stationary body with an annularly disposed static shoulder, which limits material flow and ensures uniform mixing by redirecting plasticized material radially outward and axially away from the tool, preventing hook formation and non-uniform mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a static shoulder is used in friction stir welding tool, then uniform heating and mixing are improved, but material flows upward into the tool causing fouling and maintenance issues
Solution Approach 1:
The patent inverts the traditional static shoulder design by making the shoulder rotatable instead of stationary. This reversal changes the interaction dynamics between the shoulder and material, preventing upward material flow into the tool while maintaining uniform heating and mixing capabilities through controlled rotation.
Solution Approach 2:
The patent transitions from a static shoulder configuration to a dynamic rotatable shoulder. The rotatable shoulder can rotate at controlled speeds and directions, enabling dynamic control over material flow patterns, heating uniformity, and mixing characteristics without causing material to foul the tool internals.
2Object-generated harmful factors
If pin geometry is modified to limit mixing in overlap area, then material flow into tool is reduced, but uniform mixing near surface is lost causing weld defects
Solution Approach 1:
The rotatable shoulder provides dynamic control over the mixing process. By adjusting rotation speed and direction, the system can maintain uniform mixing near the surface while simultaneously controlling material flow to prevent it from entering the tool, overcoming the limitations of static pin geometry modifications.
Solution Approach 2:
The patent changes operational parameters through rotatable shoulder rotation, enabling real-time adjustment of material flow patterns and mixing intensity. This allows the system to achieve uniform surface mixing while limiting material flow into the tool, something that fixed pin geometry cannot accomplish.
3Device complexity
If conventional friction stir welding tool is used, then simplicity of tool structure is maintained, but local heating control and uniform heating at joint are insufficient
Solution Approach 1:
The rotatable shoulder adds dynamic capability to the tool structure, enabling independent control of heating and mixing processes. This dynamic element allows for improved local heating control and uniform heating at the joint while maintaining relatively simple tool architecture through the use of a single additional rotational degree of freedom.
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 achieves a higher lap shear strength and improved weld quality by ensuring uniform mixing and preventing material flow issues, resulting in a more reliable and durable weld joint.
Implementation Method 1
Friction stir welding is currently being used in many industries for the joining of metallic materials
Implementation Method 2
redirecting plasticized material radially outward and axially away from the tool
Data Source
AI summary
A friction stir welding tool and method for forming a friction stir weld joint includes a rotatable body having a rotatable shoulder for maintaining surface contact and maintaining plunge depth and a rotatable pin extending from the rotatable shoulder. The rotatable pin is integrally formed with the rotatable shoulder. The tool further includes a stationary body annularly disposed around the rotatable body. The stationary body has a stationary shoulder annularly disposed around the rotatable shoulder for further maintaining surface contact and managing plunge depth.