Parallel Friction Stir Welding Structure for Rigid Annular Seam Joining
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Solution Overview
Problem
Existing friction stir welding apparatuses face issues with low rigidity, leading to poor welding quality and precision, especially when dealing with complex welding surfaces, due to the generation of large forging forces in series-connected structures.
Innovation Solution
A friction stir welding apparatus with a parallel mechanism comprising first, second, and third branch mechanisms, providing four degrees of freedom for the moving platform, allowing for two-dimensional rotation and movement, and a fastening device with adjustable fasteners for precise positioning and fixation of workpieces, enhancing the system's rigidity and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a series-connected structure is adopted to achieve five-axis linkage processing capability, then the apparatus can process complicated welding surfaces, but the apparatus generates large forging force which causes deformation and reduces rigidity
Solution Approach 1:
The apparatus is divided into multiple independent branch mechanisms (first, second, and third branch mechanisms) that work in parallel. Each branch mechanism handles specific degrees of freedom, segmenting the overall motion control and reducing the cumulative deformation that would occur in a series-connected structure under large forging forces.
Solution Approach 2:
Instead of using a traditional series-connected structure where mechanisms are chained sequentially, the patent inverts the architecture to a parallel mechanism where multiple branch mechanisms connect simultaneously from the fixed platform to the moving platform. This inversion fundamentally changes the force transmission path, distributing forging forces across multiple independent chains rather than accumulating them sequentially.
2Adaptability or versatility
If a series-connected structure is used, then five-axis linkage processing capability is achieved, but welding precision and welding quality deteriorate due to structure deformation
Solution Approach 1:
The patent inverts the traditional series-connected architecture to a parallel mechanism structure, where multiple branch mechanisms work simultaneously. This inversion provides sufficient rigidity to maintain welding precision while preserving the five-axis linkage processing capability needed for complicated welding surfaces.
Solution Approach 2:
The parallel mechanism structure is designed beforehand to compensate for potential deformations by distributing loads across multiple independent branches. This preemptive structural design ensures that welding precision is maintained even when processing complicated surfaces that require five-axis linkage capability.
3Manufacturing precision
If the apparatus rigidity is increased to improve welding precision, then welding quality improves, but the complexity of the apparatus increases
Solution Approach 1:
Each branch mechanism in the parallel structure serves multiple functions: it provides structural support, transmits motion, and contributes to the overall rigidity. This multi-functionality allows the apparatus to achieve high welding precision without proportionally increasing complexity, as the same structural elements fulfill multiple roles.
Solution Approach 2:
The patent merges the functions of multiple branch mechanisms into a coordinated parallel system that works together to provide both rigidity and motion control. By combining these functions in a unified parallel architecture, the apparatus achieves high welding precision while managing overall structural complexity more effectively than separate independent systems would require.
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
The apparatus achieves high rigidity, low inertia, and high dynamic performance, enabling precise welding with high accuracy and quality, particularly suitable for large-scale rocket fuel storage tank barrels, and allowing for adjustments in the diameter and length of annular seams.
Implementation Method 1
Friction stir welding uses a special form of stirring head to proceed forward while rotating, and generates heat by friction between the stirring head and the workpiece to be welded
Implementation Method 2
generates heat by friction between the stirring head and the workpiece to be welded
Implementation Method 3
generates heat by friction between the stirring head and the workpiece to be welded
Implementation Method 4
generates heat by friction between the stirring head and the workpiece to be welded
Data Source
AI summary
The presently disclosed technology includes a friction stir welding apparatus comprising a frame, a moving platform and a parallel mechanism composed of three branch mechanisms, wherein a first branch mechanism comprises a first sliding pair, a first revolute pair, a telescopic rod and a first spherical pair connected in sequence. A second branch mechanism and a third branch mechanism both comprise a third sliding pair, a second revolute pair, a third linkage and a second spherical pair connected in sequence. The friction stir welding apparatus has high stiffness, low inertia, high dynamic performance and high accuracy, which can achieve precision welding with high requirements on processing quality and accuracy for jointing annular seams of large-scale rocket fuel storage tank barrels in the aviation field, for example. The presently disclosed technology also includes a corresponding friction stir welding system.