Friction Stir Welding Re-Fluidization for Overlap Surface Defects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Friction stir welding with overlapping movement routes of the rotating tool leads to increased likelihood of defects on the front surfaces of joined members due to insufficient material intake during repeated passes with constant insertion depth.
Innovation Solution
The method involves a two-step process where the rotating tool forms a plasticized region with a first movement route and then re-fluidizes this region with a second movement route using a greater insertion depth, displacing the tool's axis and adjusting its depth to prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If friction stir welding is performed with constant insertion depth along overlapping movement routes, then uniform joining is maintained, but material intake becomes insufficient in repeated passes causing defects on front surfaces
Solution Approach 1:
The insertion depth of the rotating tool is changed dynamically between different passes. The first pass uses a first insertion depth to form the plasticized region, while the second pass uses a second insertion depth (different from the first) to re-fluidize and replenish material. This dynamic adjustment resolves the contradiction by allowing uniform joining in the first pass while preventing material deficiency and surface defects in the second pass.
2Reliability
If the rotating tool is inserted deeper to ensure adequate material intake, then surface defects are prevented, but the uniformity of joining may be compromised
Solution Approach 1:
Different insertion depths are applied locally to different passes. The first pass uses a first insertion depth appropriate for initial plasticization, while the second pass uses a second insertion depth optimized for material replenishment. This local differentiation allows each pass to operate at its optimal insertion depth, preventing surface defects while maintaining uniform joining quality through the combination of passes.
3Area of stationary object
If friction stir welding is performed on joined members with complicated shapes or closed movement paths, then complete coverage is achieved, but overlapping regions cause material thinning and defect formation
Solution Approach 1:
The friction stir welding process is performed in periodic passes over the same overlapping region. The first periodic action (first pass) forms the initial plasticized region, and the second periodic action (second pass) re-fluidizes and replenishes the material. This periodic repetition with varying insertion depths ensures complete coverage of complicated shapes while preventing material thinning and surface defects in overlapping regions.
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 approach prevents defects on the front surfaces of joined members by ensuring adequate material intake, enhances joint strength, and improves productivity by optimizing the movement routes and material distribution.
Implementation Method 1
a joining step of joining the joined members by moving the rotating tool along a movement route set on the joined members
Implementation Method 2
the rotating tool is moved to friction-stir the joined members and thereby form a plasticized region
Implementation Method 3
the rotating tool is moved in a state where the rotating tool is inserted from a same side as in the first movement route to friction-stir the joined members and thereby plastically re-fluidize a portion of the plasticized region
Implementation Method 4
plastically re-fluidize a portion of the plasticized region formed in the first movement route
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention is characterized in that it comprises a joining step of joining joined members by moving a rotating tool (F) along a movement route set on the joined members, the movement route is set up to include a first movement route along which the rotating tool (F) is moved to friction-stir the joined members and thereby form a plasticized region, and a second movement route along which the rotating tool (F) is moved in a state where the rotating tool (F) is inserted from a same side as in the first movement route to friction-stir the joined members and thereby plastically re-fluidize a portion of the plasticized region (W (Wa)) formed in the first movement route, and an insertion depth of the rotating tool (F) during the plastic re-fluidization by the rotating tool (F) in the second movement route is greater than an insertion depth of the rotating tool (F) during the formation of the plasticized region (W (Wa)) in the first movement route.