Friction Stir Welding Probe Helical Groove Oxide Film Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional friction stir welding apparatuses for overlapped metal joints face issues with void defects and reduced joint strength due to upward curling of the oxide film at the boundary face, leading to potential cracks under tensile stress.
Innovation Solution
A friction stir welding apparatus with a probe featuring a helical groove that extends beyond the overlapping plane, combined with channel-shaped grooves on the probe's peripheral surface, which promotes horizontal flow and reduces upward and downward flow, preventing oxide film curling and void defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a helical groove is formed in the probe to promote upward and downward flow of softened members, then void defects are prevented, but the oxide film curls upward reducing joint strength
Solution Approach 1:
The probe is segmented into multiple functional zones: an upper portion with a helical groove for promoting upward/downward flow, and a lower portion with a channel-shaped groove for promoting horizontal flow. This segmentation allows each zone to perform its specific function without interfering with the other, resolving the contradiction between preventing void defects and preventing oxide film curling.
Solution Approach 2:
Different regions of the probe are given different groove characteristics tailored to local requirements. The upper portion has a helical groove with specific pitch and depth for vertical flow control, while the lower portion has a channel-shaped groove for horizontal flow control. This local differentiation optimizes the flow pattern at each location to achieve both void prevention and oxide film suppression.
2Reliability
If the helical groove extends deep into the probe, then upward and downward flow is enhanced preventing voids, but horizontal flow is insufficient allowing oxide film to curl
Solution Approach 1:
The probe functionality is divided into two distinct segments: the upper segment handles vertical flow through the helical groove, while the lower segment handles horizontal flow through the channel-shaped groove. This segmentation ensures that each flow component is adequately addressed without one compromising the other.
Solution Approach 2:
The solution transitions from a single-dimension (vertical) flow control approach to a two-dimensionally integrated approach by adding the channel-shaped groove that controls horizontal flow. This dimensional addition allows simultaneous control of both vertical and horizontal material movement, preventing oxide film curling while maintaining void defect prevention.
3Device complexity
If only a helical groove is provided on the probe, then the structure is simple, but oxide film curling occurs reducing joint strength
Solution Approach 1:
Rather than using a single complex groove form, the probe uses two simpler groove types (helical and channel-shaped) placed in different locations. This segmented approach maintains relative structural simplicity while achieving the complex flow control pattern needed to prevent oxide film curling and maintain joint strength.
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 effectively suppresses upward curling of the oxide film and prevents void defects, maintaining the joint's strength by ensuring horizontal flow and reducing the occurrence of cracks, thereby enhancing the weld quality.
Implementation Method 1
While rotating the rotor (24, 34) in the direction of the arrow R about the center axis C of the rotor (24, 34), the friction stir welding apparatus (21, 31) for overlapped joints is pressed up against the surface of the upper member to be joined (22, 32) of the overlapped members (22, 32, 33) and caused to move along a prescribed joining line
Implementation Method 2
the members to be joined 22, 23 in the region surrounding the probe soften, and the softened members 22, 23 are stirred and flow plastically
Data Source
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
An object of the present invention is to provide a friction stir welding apparatus for overlapped joints capable of preventing a reduction in the strength of a joint in members to be joined by suppressing the upward curling of an oxide film. In the present invention, in a friction stir welding apparatus for overlapped joints 1 provided with a rotor 4 having a shoulder 6 and a probe 5 that is provided so as to protrude from the shoulder 6 of the rotor 4 and also so as to be disposed concentrically with the center axis C of the rotor, a helical groove 7 is formed in the peripheral surface of the probe 5, from the tip 5a of the probe 5 toward the shoulder 6, and the depth of the groove 7 is formed so as to gradually decrease from the tip 5a of the probe 5 toward the shoulder 6.