Friction Stir Welding Probe Hole Elimination
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Solution Overview
Problem
Conventional friction stir welding techniques face challenges in welding metal members with complicated shapes, resulting in probe holes and unwelded portions that reduce weld strength and quality, and complicate the joint structure.
Innovation Solution
A friction stir welding method that involves forming excess thickness portions on the members to be welded, using a welding tool with a probe to fill probe holes after initial welding, and performing subsequent weldings along lateral sides to ensure complete butt welding without probe holes, thereby improving weld strength and appearance quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If normal friction stir welding is used on members with complicated shape portions, then welding can be performed on flat or gently curved surfaces, but probe holes and unwelded portions remain in complicated shape portions reducing weld strength
Solution Approach 1:
The welding process is divided into multiple sequential steps: first welding to join the members, then probe hole filling by inserting the welding tool from the excess thickness portion, and finally removal of the excess thickness portion. This segmentation allows each step to address specific issues without compromising overall weld quality
Solution Approach 2:
Excess thickness portions are formed on the members to be welded before the welding process begins. These excess thickness portions serve as material reserves that enable subsequent probe hole filling operations, ensuring complete weld penetration and eliminating unwelded portions in complicated shape areas
2Adaptability or versatility
If multiple welding steps are used to weld complicated shape portions, then welding can be performed on angular or stepped shapes, but the joint structure becomes complicated and stress concentration occurs
Solution Approach 1:
The complicated shape portions (angular portions, stepped shapes) are extracted as separate features that require special handling. The welding tool is inserted from the excess thickness portion to specifically address these complicated areas, separating the welding function from the shape complexity and simplifying the overall joint structure
Solution Approach 2:
Different regions of the welded joint receive different treatments: the main body receives standard friction stir welding, while the complicated shape portions receive additional probe hole filling from the excess thickness portions. This localized quality enhancement ensures high weld strength where needed without unnecessarily complicating the entire joint structure
3Strength
If welding is performed to join members with complicated shape portions, then members can be joined with less thermal strain, but probe holes remain in stress concentration portions reducing weld strength
Solution Approach 1:
The probe hole, which is initially a harmful defect reducing weld reliability, is converted into a beneficial feature by filling it with material from the excess thickness portion. This transforms the harmful void into a reinforced area, eliminating stress concentration and improving both weld strength and reliability
Solution Approach 2:
The physical state of the material is changed during the probe hole filling process. The welding tool heats and plasticizes the material from the excess thickness portion, causing it to flow into and fill the probe hole. This parameter change from solid to plastic state enables complete penetration and elimination of voids, improving weld reliability
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
This method eliminates probe holes and unwelded portions near complicated shape portions, enhancing mechanical and physical weld strength and simplifying the joint structure, resulting in improved weld quality and reduced stress concentration.
Implementation Method 1
the members to be welded are stirred, softened, and plasticized to be joined together by use of frictional heat generated between the welding tool and the members to be welded
Implementation Method 2
the members to be welded are stirred, softened, and plasticized to be joined together
Data Source
AI summary
A friction stir welding method for a metal material for longitudinally welding members to be butted and then welded with complicated shape portions in section at end portions. The friction stir welding method includes preparing members to be welded and formed with excess thickness portions and a welding tool provided with a probe; performing a first welding to the members to be welded; inserting the welding tool from the excess thickness portion to cause plastic flow of the metal material subsequent to the butt-welding; and performing a second welding.