Double-Sided Friction Stir Welding Tools for Uniform Plastic Flow
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Solution Overview
Problem
Existing double-sided friction stir welding methods face challenges in achieving sufficient plastic flow and joint strength, particularly when welding structural steel, due to variations in temperature and plastic flow in the thickness direction, leading to defects and reduced welding speed.
Innovation Solution
A double-sided friction stir welding apparatus with rotating tools having end portions formed in circular and planar or convex/concave curved shapes, made of harder materials, and featuring vortex-shaped stepped portions extending opposite to the rotation direction, which are used to uniformly distribute temperature and shearing stress across the metal plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a rotating tool with a probe is used for friction stir welding, then welding can be performed on metal plates, but the probe is subjected to high stress and may break or wear, reducing tool durability
Solution Approach 1:
The invention extracts and removes the probe from the rotating tool structure. The end portion is designed as a planar or curved surface without any protruding probe, thereby eliminating the component that was previously subjected to high stress and prone to breakage or wear.
Solution Approach 2:
Instead of having a probe protrude outward to perform welding, the invention inverts the design by using a recessed or planar end surface. The welding function is achieved through the rotational friction and pressure applied by the end portion itself, rather than through a protruding probe.
2Strength
If welding is performed on structural steel with high strength at high temperature, then joint strength can be achieved, but sufficient plastic flow cannot be obtained due to low heat input and high welding speed
Solution Approach 1:
The end portion of the rotating tool is designed with a curved surface (convex or concave) instead of a flat planar surface. This curvature modifies the contact area and pressure distribution between the tool and metal plate, facilitating more uniform plastic flow across the welding interface even at high welding speeds.
Solution Approach 2:
The invention changes the geometric parameters of the tool end portion by introducing curved surfaces with specific radii of curvature. This parameter modification alters the stress and heat distribution patterns, enabling sufficient plastic flow to be achieved while maintaining high joint strength.
3Manufacturing precision
If the end portion of the rotating tool is made larger to increase contact area, then plastic flow can be improved, but the tool structure becomes more complex and harder to manufacture
Solution Approach 1:
The invention applies local quality by creating a curved surface with a specific radius of curvature at the end portion of the rotating tool. This localized geometric modification concentrates the plastic flow enhancement effect at the critical welding interface without requiring a significant increase in the overall tool size or complexity.
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 configuration facilitates uniform plastic flow and suppresses defects, enhancing joint strength and welding speed while improving tool durability by reducing stress on the probe-like structures.
Implementation Method 1
welding two metal plates by rotating a pair of rotating tools, which oppose each other, in opposite directions... heat generated between a rotating tool and the metal plates... frictional heat generated between a rotating tool and metal plates
Data Source
Figure 1
Figure 2
Figure 3(a)~3(b)
AI summary
It is an object to provide rotating tools for double-sided friction stir welding that are applied to double-sided friction stir welding, which is a technique for welding two metal plates by rotating a pair of rotating tools, which oppose each other, in opposite directions, a double-sided friction stir welding apparatus that uses the rotating tools for double-sided friction stir welding, and a double-sided friction stir welding method. A pair of rotating tools for double-sided friction stir welding that are used in double-sided friction stir welding, which is a technique for welding metal plates by using a pair of rotating tools that are each disposed on one of first and second surfaces of an unwelded portion of the metal plates such that the rotating tools rotate in opposite directions, include end portions each of which is formed in a circular and planar shape. The end portions are each made of a material harder than the metal plates.