Double-Side Friction Stir Welding for Homogeneous Plate Joints
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Friction stir welding methods face challenges in achieving homogeneous plastic flow and sufficient strength when joining metal sheets or plates due to temperature and plastic flow differences in the thickness direction, leading to welding defects and reduced welding speed.
Innovation Solution
A double-side friction stir welding method where rotating tools with shoulder and pin parts, made of harder materials, are positioned on both surfaces of the joint, with controlled gap and inclination angles to ensure uniform temperature and shear stress, and rotated in opposite directions to promote homogeneous plastic flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single rotating tool is used for friction stir welding, then the device complexity is reduced, but localized improper plastic flow occurs due to temperature and plastic flow differences in the thickness direction
Solution Approach 1:
The welding process is segmented into two sides by using a pair of rotating tools (first rotating tool on top surface, second rotating tool on bottom surface) that simultaneously perform friction stir welding from both sides of the metal sheet, eliminating the localized improper plastic flow that occurs with single-sided welding
2Productivity
If welding speed is increased to improve productivity, then output per unit time increases, but localized improper plastic flow occurs due to insufficient heat generation and plastic flow
Solution Approach 1:
The welding process is segmented into two sides with simultaneous welding operations, allowing higher welding speeds while maintaining sufficient heat generation and plastic flow homogeneity through the combined effect of both rotating tools
Solution Approach 2:
The rotation directions of the first and second rotating tools are set to be opposite to each other, creating optimized frictional heat generation and plastic flow patterns that enable high-speed welding without compromising joint quality
3Ease of operation
If the rotating tools are rotated in the same direction, then the device operation is simplified, but improper plastic flow occurs in the welded joint due to asymmetric temperature and stress distribution
Solution Approach 1:
The rotation directions of the first and second rotating tools are deliberately set to be opposite to each other, creating a symmetric thermal and mechanical field that produces homogeneous plastic flow and eliminates welding defects caused by asymmetric temperature and stress distribution
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 enhances welding speed, suppresses defects, and ensures sufficient joint strength by achieving a homogeneous welded state across the thickness direction, improving workability and joint quality.
Implementation Method 1
while the metal sheets or the metal plates are softened by frictional heat generated between the rotating tools and the metal sheets or the metal plates
Implementation Method 2
softened parts are stirred by the rotating tools. As a result, a plastic flow is caused to occur at the welded joint
Data Source
AI summary
Provided is a double-side friction stir welding method of metal sheets or metal plates to each other, and a double-side friction stir device for performing the double-side friction stir welding. According to the present invention, a pair of rotating tools facing each other is respectively arranged on a top-surface side and a bottom-surface side of a butted portion or an overlapping portion, which comprises a joint portion of two metal sheets or two metal plates, the pair of rotating tools is moved in a welding direction while being rotated at the butted portion or the overlapping portion, and while the metal sheets or the metal plates are softened by frictional heat generated between the rotating tools and the metal sheets or the metal plates, softened parts are stirred by the rotating tools to produce a plastic flow to join the metal sheets or the metal plates to each other.