Friction Stir Welding with Pin-Only Contact for Deep Joints
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Solution Overview
Problem
Conventional friction stir welding methods face challenges when joining metal members of large thickness, as the increased outer diameter of the stirring pin and shoulder portion lead to higher friction and load on the apparatus, making deep location joining difficult, and can result in gaps and damage to the metal members.
Innovation Solution
The method limits contact to the stirring pin only, allowing it to be inserted deep into the metal members, reducing friction and load, and includes secondary joining processes from both surfaces to ensure deep penetration and air-tightness, with optional refill processes to address metal deficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the outer diameter of the stirring pin and shoulder portion is increased to join thick metal members, then the joining depth is improved, but the friction and load on the apparatus increase
Solution Approach 1:
The invention extracts the shoulder portion from the friction stir welding tool, leaving only the stirring pin to contact the metal members. This removes the source of excessive friction and load while preserving the stirring pin's ability to create plasticized regions for joining thick metal members at deep locations
Solution Approach 2:
The invention introduces a refill member as an intermediary material that is inserted into the stirring pin's path after welding. This refill member compensates for the reduced material displacement caused by removing the shoulder portion, ensuring complete filling of the joint region without requiring increased tool dimensions or force
2Length of stationary object
If the outer diameter of the shoulder portion is increased to join thick metal members, then the joining depth is improved, but the apparatus complexity increases
Solution Approach 1:
The invention simplifies the apparatus by extracting and removing the complex shoulder portion structure, retaining only the essential stirring pin. This reduction in tool complexity makes the apparatus more manageable while still achieving deep joining through the stirring pin's rotational action and the subsequent refill process
3Ease of manufacture
If conventional friction stir welding is used on inner corner portions, then the joining process is simplified, but the metal members are damaged by the holding block
Solution Approach 1:
The invention removes the holding block from the friction stir welding tool, eliminating the source of damage to metal members. The stirring pin alone performs the welding function by creating plasticized regions that join the metal members without the harmful scraping action of the holding block
Solution Approach 2:
The invention performs preliminary action by inserting the refill member into the stirring pin's path after the welding process. This preliminary filling action compensates for any material deficiencies created by the simplified tool, ensuring complete joint formation without damaging the metal members during the welding process itself
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 enables successful joining of thick metal members down to a deep location with reduced damage and enhanced air-tightness and water-tightness, while minimizing the load on the friction stirring apparatus.
Implementation Method 1
the stirring pin is rotated, while the holding block 111 is in contact with respective side surfaces of the metal members 101, 102
Implementation Method 2
the plasticized regions formed in the friction stir welding
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention aims at providing a friction stir welding method which can achieve joining a butting portion to a deep location therein by reducing the load on the friction stirring device. The friction stir welding method for joining two metal members (1) using a primary joining rotary tool (F) with a stirring pin (F2) includes a primary joining process in which a rotating stirring pin (F2) is moved to the butting portion formed by butting the metal members (1) against each other and friction stir welding is carried out. In the primary joining process, only the stirring pin (F2) is brought into contact with the metal members (1).