Friction Stir Welding Tool Exit Control via Variable Rotation Speed
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Solution Overview
Problem
Friction stir welding often results in increased material ejection or longer exit traces, leading to costly rework and reduced weld seam strength due to abrupt tool emergence from the plasticized material, which disrupts the structural integrity and increases the risk of cracks.
Innovation Solution
A device and method for friction stir welding that incorporates a welding shoe with a circular base, transverse web, and notch-like taper, which reduces material compression and facilitates smooth tool exit, ensuring a high-quality weld seam and minimizing contamination by using a welding pin tip with a conical design and a pressure-generating system for cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the friction stir welding tool is used to weld workpieces, then the weld joint is created, but material ejection and longer exit traces occur leading to costly rework
Solution Approach 1:
The patent applies preliminary action by gradually reducing the tool rotation speed during the welding process, particularly during the exit phase. This controlled deceleration prepares the plasticized material for gradual tool withdrawal, preventing abrupt emergence that causes material ejection and exit traces, thereby maintaining weld seam quality while preserving welding productivity.
Solution Approach 2:
The patent implements dynamics by making the tool rotation speed variable throughout the welding process. The rotation speed is dynamically adjusted - higher during the welding phase for productivity, and gradually reduced during the exit phase to prevent material ejection. This dynamic control resolves the contradiction between maintaining high welding speed and ensuring weld seam quality.
2Loss of time
If the tool emerges abruptly from the plasticized material, then the welding process is completed faster, but the structural integrity is disrupted and crack risk increases
Solution Approach 1:
The patent applies preliminary action by gradually reducing the tool rotation speed before complete tool withdrawal. This controlled deceleration prepares the plasticized material for gradual tool emergence, preventing abrupt withdrawal that disrupts structural integrity and creates cracks. The preliminary speed reduction maintains reliability while minimizing additional welding cycle time.
Solution Approach 2:
The patent implements continuity of useful action by maintaining tool rotation throughout the entire welding process, including the exit phase, but at a gradually reduced speed. This continuous rotational action ensures smooth material flow and gradual tool emergence, preventing structural disruption and crack formation, thereby maintaining weld seam strength without significantly extending the welding cycle.
3Manufacturing precision
If higher pressure is applied during friction stir welding, then the weld quality is improved, but the load on the friction stir welding system increases
Solution Approach 1:
The patent implements dynamics by making the tool rotation speed variable throughout the welding process. The rotation speed is dynamically adjusted - higher during the welding phase for productivity, and gradually reduced during the exit phase to prevent material ejection. This dynamic control resolves the contradiction between maintaining high welding speed and ensuring weld seam quality.
Solution Approach 2:
The patent applies periodic action through a multi-phase welding process with distinct stages: acceleration phase, constant speed welding phase, and deceleration exit phase. Each phase has optimized parameters - the deceleration phase specifically uses reduced rotation speed to prevent material ejection and exit traces, resolving the contradiction between productivity and weld seam quality.
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 enhances weld seam quality, reduces rework, and minimizes tool contamination by ensuring a controlled and clean exit process, resulting in improved structural integrity and reduced risk of cracks.
Implementation Method 1
a friction stir tool is introduced into the material of the workpieces to be welded with a rotating movement and pressure is applied and is guided along a connection point of the workpieces to be welded
Implementation Method 2
at least one sensor for detecting the acceleration forces acting on the tool body is integrated in the tool body
Implementation Method 3
a pressure-generating system for cleaning
Data Source
Figure 1
Figure 2
Figure 3a~3e
AI summary
Apparatus and method for increasing the quality of the weld seam in friction stir welding, with the following features: a) a receiving plate (1) with a drive head (2), the latter having a receiving flange (19) for receiving a holding bell (3) connected by means of a union nut (7) to a welding shoe (4) with a welding pin tip (5), b) the welding shoe (4) has a circular basic shape, on which there is a transverse web running over the cross section and rising at a right angle to said basic shape, said transverse web having a width of approximately 1/4 to 1/5 of the diameter of the basic shape and having an arc-shaped shoe sliding surface and shoe smoothing surface (9), c) the welding pin tip (5) has substantially a surface structure in the form of a tapering thread, this thread-like structure not being arranged in a purely circular manner.