Friction Stir Welding of Inner Corners Without Metal Shortage
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Solution Overview
Problem
Conventional friction stir welding methods result in plastic fluidized metal overflowing outside the inner corner, leading to a shortage of metal in the inner corner.
Innovation Solution
A friction stir welding method using a rotary tool with a stirring pin and a shoulder to retain plastic fluidized metal, where the stirring pin has a spiral groove to guide the metal inward and the shoulder prevents overflow, ensuring adequate metal retention in the inner corner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If only a stirring pin is inserted into the inner corner without a shoulder, then friction stir welding can be performed to a deeper position, but plastic fluidized metal overflows outside the inner corner causing metal shortage
Solution Approach 1:
The rotary tool is divided into two functional parts: a stirring pin for deep insertion and welding, and a shoulder for metal retention. This segmentation allows each part to perform its specific function - the stirring pin reaches deep into the inner corner while the shoulder prevents metal overflow at the surface.
Solution Approach 2:
The shoulder acts as an intermediary element between the stirring pin and the metal members. It provides a retaining function that prevents plastic fluidized metal from overflowing, while allowing the stirring pin to perform the welding operation at depth.
2Quantity of substance
If a shoulder is added to the rotary tool to retain metal, then metal overflow is prevented, but the tool complexity increases
Solution Approach 1:
The rotary tool is designed with multi-functionality by integrating both stirring and retaining functions into a single tool. The shoulder portion provides metal retention while the stirring pin portion performs the welding operation, eliminating the need for separate tools or additional components.
Solution Approach 2:
The stirring pin and shoulder are merged into a single integrated rotary tool structure. This combination allows the tool to simultaneously perform metal retention through the shoulder and deep welding through the stirring pin, reducing the number of separate components needed.
3Productivity
If the stirring pin is rotated at high speed to perform friction stir welding, then welding efficiency increases, but metal overflow outside the inner corner is exacerbated
Solution Approach 1:
The shoulder provides a counteracting function to the centrifugal force generated by high-speed rotation of the stirring pin. It acts as a barrier that prevents plastic fluidized metal from being thrown outward by the rotational force, thereby controlling metal overflow while maintaining high welding efficiency.
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 method effectively prevents metal overflow and ensures sufficient metal deposition in the inner corner, addressing the shortage issue and enhancing the quality of the weld.
Implementation Method 1
friction stir welding is performed to the abutment part while bringing only the stirring pin into contact with the metal members
Implementation Method 2
plastic fluidized metal is not retained by a shoulder, to cause the plastic fluidized metal to be overflowed outside the inner corner
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
A friction stir welding method is provided that can prevent defective welding due to a shortage of metal. The friction stir welding method welds metal members (1, 2) using a primary joining rotary tool (F) having a stirring pin (F2), and includes steps of: butting in which the metal members (1, 2) are butted with each other at an angle to form a butted portion (J1); buildup welding in which buildup welding is applied along an inner corner of the metal members (1, 2) formed in the butting step to cover the inner corner by a weld metal (M); and inner corner joining in which only the stirring pin (F2) in rotation is inserted in the inner corner to plastically fluidize the weld metal (M) and the metal members (1, 2) for friction stir welding of the butted portion (J1).