Friction Stir Welding Tool Surface Affinity Control
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Solution Overview
Problem
Existing double-acting friction stir welding and spot welding techniques face issues with workpiece adhesion between the pin member and shoulder member, leading to malfunction and reduced weld quality, particularly with aluminum-based materials, and existing coatings are ineffective in preventing adhesion and are costly.
Innovation Solution
A welding tool configuration where the pin member and shoulder member have non-affinity surfaces treated with diamond or hydrogen-free diamond-like carbon (DLC) coatings, with the shoulder member's contact surface having affinity for the workpiece to ensure sufficient friction, while the pin member's surface remains non-affine to prevent adhesion, and a suitable clearance between components to prevent workpiece entry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the pin member and shoulder member surfaces are made with high affinity for the workpiece to ensure sufficient friction for welding, then the welding process can proceed effectively, but the workpiece material adheres to the tool surfaces causing malfunction and reduced tool life
Solution Approach 1:
The invention applies different surface properties to different regions of the tool. The pin member contact surface has high affinity for the workpiece to generate sufficient friction for welding, while the shoulder member inner peripheral surface has low affinity (non-affinity) to prevent adhesion of workpiece material, thus resolving the contradiction between needing friction for welding and preventing adhesion-induced malfunction
Solution Approach 2:
The tool is segmented into two functional zones: the pin member contact surface that interacts with the workpiece front surface for friction generation, and the shoulder member inner peripheral surface that interfaces with the workpiece bulk material. Each segment is given appropriate surface properties for its specific function, allowing simultaneous achievement of welding effectiveness and adhesion prevention
2Reliability
If conventional coatings (aluminum oxide, titanium carbide, titanium nitride, aluminum nitride) are applied to the tool surfaces to prevent adhesion, then adhesion resistance is improved, but the tool cost increases significantly and the coatings are ineffective for aluminum-based materials
Solution Approach 1:
The invention changes the surface parameter (affinity) of the shoulder member inner peripheral surface by applying a specific coating formulation that creates low affinity for aluminum-based materials. This parameter change enables effective adhesion prevention for aluminum workpieces without requiring expensive conventional coatings, thus resolving the contradiction between adhesion prevention effectiveness and manufacturing cost
3Reliability
If the pin member contact surface has non-affinity for the workpiece to prevent adhesion, then tool reliability is improved, but insufficient friction force is generated for effective welding
Solution Approach 1:
The pin member contact surface is given high affinity for the workpiece to generate sufficient friction force for welding, while the shoulder member inner peripheral surface is given low affinity to prevent adhesion. This local differentiation of surface properties resolves the contradiction between needing friction for welding and preventing adhesion
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 effectively prevents workpiece adhesion, reduces tool wear, and enhances weld quality by minimizing surface irregularities and tool damage, allowing for efficient and high-quality welding with reduced tool life degradation.
Implementation Method 1
a welding tool configuration where the pin member and shoulder member have non-affinity surfaces treated with diamond or hydrogen-free diamond-like carbon (DLC) coatings
Implementation Method 2
Friction stir welding is a technique in which a columnar pin member that is a rotary tool is pushed (pressed) into a workpiece made of a metal material, such that the metal material is softened and stirred
Data Source
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AI summary
A double-acting friction stir welding tool according to the present invention at least includes: a columnar pin member (11); and a shoulder member (12) positioned outside the pin member (11) and having a cylindrical shape, the shoulder member (12) being configured to rotate around an axis, which is the same as an axis of rotation of the pin member (11). A contact surface (11a) and an outer peripheral surface (11b) of the pin member (11), the contact surface (11a) coming into contact with a workpiece (60), have non-affinity for the workpiece (60). The shoulder member (12) is configured such that an inner peripheral surface (12b) and an outer peripheral surface (12c), the inner peripheral surface (12b) facing the pin member (11), have non-affinity for the workpiece (60), and only a contact surface (12a) coming into contact with the workpiece (60) has an affinity for the workpiece (60). A clearance between the pin member (11) and the shoulder member (12) may be suitably set.