Fixed-Shoulder Friction Stir Welding for Smooth Corner Fillets
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Solution Overview
Problem
Friction stir welding with a fixed shoulder tool often results in surface defects on fillets formed during the welding of aluminum workpieces, particularly when the welded length is long, due to material adherence to the shoulder and subsequent scratching.
Innovation Solution
A friction stir welding device with a fixed shoulder that maintains a gap between the shoulder and the workpiece surfaces, using a control unit to manage the position of the shoulder and supply filler to the stirring region, preventing material adherence and surface defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed shoulder friction stir welding tool is used to weld corner portions of workpieces, then the welding process can be performed, but surface defects such as roughness occur on the fillet surface
Solution Approach 1:
A filler material is introduced as an intermediary substance between the fixed shoulder tool and the workpiece corner portion. The filler prevents direct contact and adhesion between the softened workpiece material and the fixed shoulder, thereby preventing surface defects on the fillet while enabling the welding process to proceed
Solution Approach 2:
The gap between the fixed shoulder and the workpiece surface is controlled within a specific range (0.5mm to 2.0mm). This parameter change prevents the softened material from reaching and adhering to the fixed shoulder, eliminating the cause of surface defects while maintaining welding effectiveness
2Stability of the object's composition
If the fixed shoulder contacts the workpiece surface during friction stir welding, then the welding process is stable, but material adheres to the shoulder and scratches the fillet surface
Solution Approach 1:
The filler material serves as a mediator that prevents direct contact between the softened workpiece material and the fixed shoulder. This eliminates the harmful adhesion and scratching effects while allowing the welding process to remain stable
Solution Approach 2:
The filler material is supplied in advance to the corner portion before the softened material can reach the fixed shoulder. This preliminary protective action prevents adhesion and scratching from occurring in the first place
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
Inhibits the occurrence of surface defects on fillets formed during friction stir welding by ensuring the fixed shoulder does not contact the workpiece surfaces, allowing the filler to form a smooth fillet without adhering material.
Implementation Method 1
a stirring region which is stirred by the probe at the time of friction stir welding
Implementation Method 2
holding the fixed shoulder of the friction stir welding tool with the probe immersed in the welding portion, at a position separated by a gap from the surface of the workpiece
Implementation Method 3
a filler supply unit which supplies a filler to the stirring region... forms a fillet (reinforcement) at a corner portion
Data Source
AI summary
A friction stir welding device includes a friction stir welding tool equipped with a fixed shoulder on an outer periphery of a probe on a proximal end side, a main shaft positioning mechanism which relatively moves the friction stir welding tool with respect to a corner portion between workpieces a control device thereof, and a filler supply unit which supplies a filler to a stirring region in which the workpieces are stirred by the probe at the time of friction stir welding. When the probe is immersed into the corner portion to perform the friction stir welding, the fixed shoulder is maintained at a position separated by a gap from the surfaces of the workpieces with the control device.