Double-Sided Refill Friction Stir Spot Welding Beyond Plunge Depth
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Solution Overview
Problem
Conventional refill friction stir spot welding techniques face limitations such as constrained welding depth, inability to weld thicker joints, and challenges with multi-stack joints due to high melting temperatures of intermediate materials.
Innovation Solution
The method involves using two welding heads with probe members and tubular shoulders, simultaneously rotating and advancing these components into the weld object from both sides to create a volume of increased plasticity, thereby overcoming the limitations of conventional techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional refill FSSW is used to avoid consumable material and exit holes, then welding cleanliness is improved, but welding depth is constrained by machine plunge depth
Solution Approach 1:
The welding process is divided into two simultaneous operations from opposite sides: one welding head creates a recess while the other fills it. This segmentation allows each head to work within its plunge depth capability while achieving a combined welding depth that exceeds individual limitations, solving both the exit hole problem and the depth constraint.
Solution Approach 2:
The solution transitions from single-sided welding to dual-sided simultaneous welding, adding a dimensional aspect to the process. By operating welding heads from both surfaces of the workpiece, the system overcomes the plunge depth limitation of individual heads while maintaining cleanliness by preventing material ejection through coordinated opposite-side operations.
2Loss of substance
If conventional refill FSSW is used, then consumable material is eliminated, but welding time increases and previous welds may degrade when performing sequential welds
Solution Approach 1:
The dual-headed system enables continuous welding operations without the need to reposition or reset equipment between sequential welds. By maintaining both welding heads in operative positions simultaneously, the system eliminates idle time and allows continuous progression along the weld line, improving productivity while maintaining the consumable-free advantage.
3Device complexity
If conventional refill FSSW is used, then simple tool design is maintained, but ability to weld multi-stack joints with high melting temperature materials is lost
Solution Approach 1:
The dual welding head system provides multi-functionality by enabling welding of various configurations including single-layer joints, multi-stack joints, and joints with intermediate materials of different melting points. The coordinated operation of opposing heads allows adaptation to diverse material combinations and joint geometries while maintaining a relatively simple overall tool design.
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 deeper welds, increased welding efficiency, and the ability to weld thicker joints in a single step, while also addressing the challenges of multi-stack joints by effectively managing heat distribution and material plasticity.
Implementation Method 1
Friction stir welding is a solid state joining process that uses frictional heat generated by a rotating tool to join materials
Implementation Method 2
utilizes a redesigned tool to achieve spot welding without exit-hole by advancing a probe into the object to be welded while simultaneously retracting a tubular shoulder surrounding the probe, with both the probe and the shoulder being rotated. During this movement, material plasticised by friction between the probe and the object to be welded
Data Source
AI summary
A method for performing simultaneous double refill friction stir spot welding includes: providing a first welding head comprising a first probe member and a first tubular shoulder; providing a second welding head comprising a second probe member and a second tubular shoulder; locating the first welding head on a first surface of a weld object to be welded such that the first probe member and the first tubular shoulder are in contact with the first surface; locating the second welding head on a second surface of the weld object, opposing the first surface; simultaneously rotating the first welding head and the second welding head so as to form a volume of materials of increased plasticity in the weld object proximate the first and second welding heads.