Friction Stir Welding Shoulder Roughness for Lower Drag Force
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Solution Overview
Problem
Friction stir welding causes surface cracks in welds, leading to fragile welds and a significant drag force that can result in premature tool breakage.
Innovation Solution
A friction stir welding tool with a shoulder having a face with an arithmetic mean roughness of less than or equal to 0.8, which improves tribological properties, reducing the coefficient of friction and drag force, and enhancing weld quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shoulder face has high roughness, then the welding process is simpler, but the drag force increases and weld quality deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the surface roughness parameter of the shoulder face from conventional high roughness to a controlled low roughness range (Ra ≤ 0.8 μm). This parameter optimization reduces the coefficient of friction between the shoulder face and workpiece surface, thereby reducing drag force while improving weld quality and preventing surface cracking.
2Duration of action of stationary object
If the shoulder face has high roughness, then manufacturing is easier, but the tool service life decreases due to premature pin breakage
Solution Approach 1:
The patent optimizes the surface roughness parameter to Ra ≤ 0.8 μm through controlled machining or finishing processes. While this requires more precise manufacturing than conventional rough surfaces, the resulting reduction in drag force and friction significantly extends tool service life by preventing premature pin breakage, thereby achieving better overall manufacturing efficiency.
3Productivity
If the shoulder face has high roughness, then no additional treatment is needed, but the coefficient of friction increases reducing welding efficiency
Solution Approach 1:
The patent changes the surface roughness parameter to Ra ≤ 0.8 μm, which optimizes the tribological properties of the shoulder face. This parameter optimization reduces the coefficient of friction, allowing for higher welding speeds and improved productivity while maintaining stable welding forces and preventing material adhesion to the shoulder face.
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 improved tribological properties of the tool reduce the drag force, enhance weld quality, and extend the service life of the welding tool, allowing for faster and more efficient welding with reduced forging force.
Implementation Method 1
reducing the arithmetic mean roughness of the face has the effect of reducing the coefficient of friction and thus making the shoulder slide better on the parts to be welded
Data Source
Figure 1~2
Figure 3a~3b
Figure 4a~4b
AI summary
The present disclosure relates to a friction stir welding tool (1), the tool (1) comprising: - a rotating external pin (2); and - a body (5) having a shoulder surrounding the pin (2), the shoulder (3) comprising at least one face (30) configured to be in contact with parts (21, 22) to be welded, an arithmetic mean roughness of the face (30) being less than or equal to 0.8.