Multi-Probe Friction Stir Welding for Fiber Metal Butt Joints
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Solution Overview
Problem
Existing methods for joining fiber metal laminates, such as those used in aircraft construction, are labor-intensive and inefficient, particularly when aiming to avoid material overlap in lap joints, and do not effectively account for the different thermal and material properties of metal and thermoplastic layers during friction stir welding.
Innovation Solution
A friction stir welding method and device utilizing a probe assembly with multiple probe devices, each adapted to specific layers with different material properties, allowing for simultaneous welding of metal and thermoplastic layers with varying thermal conductivities, enabling efficient and optimized butt joint welds in fiber metal laminates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single probe is used for friction stir welding throughout the whole thickness of the laminates, then the device complexity is reduced, but the welding quality and efficiency deteriorate because it cannot account for different material properties of metal and thermoplastic layers
Solution Approach 1:
The probe assembly is segmented into multiple independent probe devices, each dedicated to welding specific material layers. The first probe device welds metal layers while the second probe device welds thermoplastic layers, allowing each probe to be optimized for its specific material type and achieve high welding quality without excessive complexity
Solution Approach 2:
Each probe device is configured with local quality characteristics suited for its target material. The first probe device has parameters optimized for metal welding while the second probe device has parameters optimized for thermoplastic welding, enabling precise control of welding processes for different materials simultaneously
2Productivity
If friction stir welding is performed on fiber metal laminates with alternating metal and thermoplastic layers, then the productivity increases compared to traditional joining methods, but the device complexity increases due to the need for multiple probe devices to handle different material properties
Solution Approach 1:
Multiple probe devices are merged into a single integrated probe assembly that operates simultaneously on different layers. This combining approach maintains high productivity by welding all layers in one pass while managing device complexity through integrated design and coordinated control of the multiple probes
Solution Approach 2:
The probe assembly is designed as a multi-functional system where each probe device can handle specific material types (metal or thermoplastic). This universality allows the assembly to process complex multi-layer laminates efficiently without requiring separate welding operations for each layer type
3Reliability
If traditional joining methods with rivets or bolts are used, then the reliability of the joint is maintained, but the weight of the workpiece increases due to material overlap needed for lap joints
Solution Approach 1:
The mechanical fastening system (rivets or bolts) is replaced with a friction stir welding process that creates metallurgical bonds. This substitution eliminates the need for material overlap and fastening elements, significantly reducing workpiece weight while maintaining or improving joint reliability through direct material bonding
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 allows for rapid, efficient, and high-quality butt weld seams in fiber metal laminates, optimizing the welding process by accounting for the unique properties of each layer, resulting in lightweight, resilient, and reliable joints suitable for aerospace applications.
Implementation Method 1
The material of the sheets is heated up using frictional heat generated by a rotating probe acting on the sheets at the location of the joint
Implementation Method 2
When the probe moves away from a section of the joint, the plasticized material of both sheets has become mixed, and as the temperature drops, the plastic state quickly solidifies
Data Source
AI summary
A method for friction stir welding along a butt joint weld line (40). A welding device (70) includes a probe assembly (90) including at least a first and second probe device (100a, 100b). A first and second part (31a, 31b) to be joined along the weld line (40) are provided, wherein the parts are each formed as a laminate (1; 1′) including at least a first layer (2a, 2b) formed with a first material and a second layer (5a, 5b) formed with a second material. The first and second materials have different material properties. The method friction stir welds of the parts using the welding device, wherein simultaneously the first probe device acts on the first layers and the second probe device acts on the second layers.