Inner-Corner Friction Stir Welding to Prevent Metal Shortage
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Solution Overview
Problem
Conventional friction stir welding methods fail to retain plastic fluidized metal, leading to overflow and a shortage of metal in the inner corner, resulting in potential joining defects.
Innovation Solution
A friction stir welding method that includes steps of butting, buildup welding, and inner corner joining, where a rotary tool with a stirring pin is used to insert into a weld metal to plasticize and join metal members, with optional auxiliary members to cover the inner corner and prevent overflow, ensuring a stable and complete join.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If only a stirring pin of a rotary tool is inserted in an inner corner to carry out friction stir welding, then welding can be performed to a deeper position, but plastic fluidized metal overflows outside the inner corner causing a shortage of metal in the inner corner
Solution Approach 1:
Buildup welding is performed in advance along the inner corner to form a weld metal that covers the inner corner before the friction stir welding process begins. This preliminary action ensures sufficient metal is available in the inner corner during subsequent friction stir welding, preventing metal shortage while enabling deep welding.
Solution Approach 2:
An auxiliary member is introduced as an intermediary element placed on the inner corner during friction stir welding. This auxiliary member prevents plastic fluidized metal from overflowing outside the inner corner, ensuring metal is retained where needed while allowing the stirring pin to reach deeper positions.
2Quantity of substance
If buildup welding is applied to cover the inner corner with weld metal, then metal shortage is prevented, but the process complexity increases
Solution Approach 1:
Buildup welding is performed as a preliminary step before friction stir welding to deposit weld metal along the inner corner. This ensures sufficient metal availability in advance, preventing metal shortage during the main welding process while maintaining a systematic approach to solving the problem.
Solution Approach 2:
An auxiliary member made of inexpensive material is used temporarily during friction stir welding to prevent metal overflow. This disposable element is removed after welding, avoiding the need for complex permanent structures while solving the metal retention problem.
3Quantity of substance
If an auxiliary member is arranged on the inner corner to prevent overflow, then metal retention is improved, but the ease of operation decreases
Solution Approach 1:
An auxiliary member is introduced as a temporary intermediary element that simplifies the overall process by preventing metal overflow. Although it adds a step to the operation, it eliminates the need for complex tool modifications and ensures consistent results, improving ease of operation in the long run.
Solution Approach 2:
The auxiliary member is a simple, inexpensive, disposable component that is easy to install and remove. Its temporary nature allows it to perform its function of preventing metal overflow without requiring complex integration into the welding system, maintaining operational simplicity.
4Strength
If the entire butted portion is thoroughly joined including outer corner, then joining strength is enhanced, but the welding time increases
Solution Approach 1:
The welding process is divided into distinct segments: buildup welding along the inner corner, friction stir welding of the inner corner, and friction stir welding of the outer corner. This segmentation allows each area to be optimized independently, ensuring thorough joining for strength while managing overall process efficiency.
Solution Approach 2:
The buildup welding and friction stir welding processes are combined in a systematic sequence, and the inner corner and outer corner welding are performed as integrated steps. This merging ensures complete coverage of the entire butted portion for maximum joining strength while maintaining process efficiency through coordinated execution.
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 effectively addresses the shortage of metal in the inner corner, enhances joining strength, and improves air and water tightness by ensuring the entire butted portion is thoroughly joined, preventing defects and maintaining metal integrity.
Implementation Method 1
inner corner joining in which only the stirring pin in rotation is inserted in the weld metal and the inner corner to plastically fluidize the weld metal and the metal members for friction stir welding of the butted portion
Implementation Method 2
buildup welding in which buildup welding is applied along an inner corner of the metal members formed in the butting step to cover the inner corner by a weld metal
Data Source
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).