Self-Reacting Friction Stir Welding Tool for Propellant Tanks
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Solution Overview
Problem
Friction stir welding requires a backing member to counteract the forces generated by the weld tool, which complicates the process and increases costs, especially when welding propellant tanks, as it necessitates internal support and subsequent removal, potentially causing damage and requiring costly retesting.
Innovation Solution
A self-reacting friction stir welding tool with external support rings that counteract the forces externally, eliminating the need for an internal mandrel and allowing for complete penetration of the weld, reducing forge forces and enabling welding without internal tools, thus simplifying the process and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an internal mandrel is used to counteract forces during friction stir welding, then welding can be performed, but the process becomes more complex and costly due to the need for internal support and subsequent removal
Solution Approach 1:
The patent inverts the traditional approach by moving the support structure from inside the workpiece to outside. Instead of using an internal mandrel that must be inserted and later removed, external support rings are positioned around the workpiece to counteract welding forces, eliminating the need for internal intervention and subsequent removal operations.
Solution Approach 2:
The internal mandrel is extracted from the welding system and replaced with an external support structure. This removes the problematic element that required insertion into and removal from the workpiece, simplifying the overall process while maintaining the necessary force counteraction.
2Force
If an internal mandrel is used for support, then welding forces are counteracted, but the risk of tank damage increases and retesting costs rise
Solution Approach 1:
External support rings act as intermediary structures that provide the necessary force counteraction without直接接触 (direct contact) with the interior of the tank. These rings distribute welding forces externally, preventing damage to the tank while maintaining process integrity.
Solution Approach 2:
The external support rings are positioned in advance to prevent potential damage before it occurs. By having the support structure in place during welding, the system preemptively counteracts forces that would otherwise damage the tank, eliminating the need for costly retesting.
3Productivity
If traditional friction stir welding with internal mandrel is used, then welding can be completed, but the process time increases due to mandrel removal and potential retesting
Solution Approach 1:
The time-consuming step of internal mandrel removal is eliminated by extracting the support function to external rings. This allows the welding process to proceed continuously without interruption for internal tool removal, significantly reducing cycle time.
Solution Approach 2:
The external support rings enable continuous welding operation without the interruptions required by internal mandrel removal and potential retesting. The support structure remains in place throughout the entire welding process, maintaining continuous productive action.
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 reduces the need for internal supports, decreases weld defects, minimizes tank damage, and simplifies the welding process by allowing complete penetration and reducing the complexity of propellant tank fabrication, while also reducing the time and cost associated with welding operations.
Implementation Method 1
Friction between the rotating pin and work pieces causes localized heating and plasticizing of the material adjacent to the pin
Implementation Method 2
contact between the pin and the work pieces generates heat that causes the material to yield
Implementation Method 3
Heating reduces the yield stress of the material properties of the parent material... the material to yield, thereby allowing the pin to plunge into the work pieces
Data Source
AI summary
A friction stir welding system is provided herein. More specifically, traditional friction stir welding requires a rotatable head that is forced against a plurality of work pieces to bond the same. The rotational and normal forces generated by the friction stir welding tool are generally reacted by a backing plate, anvil, mandrel or other mechanisms, such hardware are subject to the applied forces and are often supported with additional internal supports. Conversely, a friction stir weld system is described that omits the need for such a backing member and internal supports as it is performed using a self reacting pin tool.